RMS AAPG 2026 PROGRAM BOOK V1

2026

RMS-AAPG ANNUAL MEETING Butte, Montana

OCT 24-26 Full Program Book

Dear 2026 RMS-AAPG Attendees-

RMS-AAPG CHAIRS WELCOME LETTER

Welcome to Butte, America! The Montana Geological Society and the Rocky Mountain Section of AAPG are pleased to welcome you once again to Big Sky Country. We are excited to be hosting the 2026 RMS-AAPG Annual Meeting in Butte, Montana – the richest hill on earth! The stunning landscape and geology of Montana have served as the backdrop for thousands of years of humankind’s endeavors. Native peoples relied on the land to provide sustenance for the body and soul. The Journey of Discovery navigated the Missouri River from the mouth of the Yellowstone to the Bitterroot Mountains in 1804, detailing for the first time in written words the vast wilderness that was to become Montana. Natural resource development began with the discovery of gold at Gold Creek, just east of Drummond, in the spring of 1858. Shortly after this initial discovery, in 1862, a gold rush to Montana started after word of a big gold strike at Grasshopper Creek, south of Dillon, made the news. Would-be miners from all over the world ventured to the gold camps of western Montana. The period of the 1860's through the 1880's was a turbulent and wild time in Montana with changing capitals that followed new gold discoveries. By the 1890's, gold began taking a secondary role to copper, and Butte became a major town and considered one of the most prolific mining districts in the world earning it the title “Richest Hill on Earth”, where mining persists to date. The first mention of oil and gas in Montana is not less colorful and dates back to the time of the gold rush to Montana. In 1864 members of an immigrant train discovered an oily sheen on a pool of water near the Big Horn River, east of Billings, and used the oil to grease the axles of their wagon. Petroleum development followed the mining boom with the first oil well drilled in 1901 at Kintla Lake on the east side of Glacier National Park where natural seeps had been known to native tribes. Significant discoveries followed in the 1910s and 1920s, with the first permanent Montana oil field established in Elk Basin in 1915 and the discovery of the major Kevin Sunburst field in northern Montana in 1922, creating a robust oil and gas industry. In the 1990s a novel approach using horizontal drilling and hydraulic fracture stimulation in the Bakken Formation resulted in the nation’s first oil resource play. This rich and colorful natural resource heritage of our state, and Butte in particular, provides an appropriate backdrop for conversations about the geological sciences, resource exploration and development, and the changing role of earth scientists and engineers in modern resource industries. While Montana continues to provide mineral and petroleum resources, the next generation of geoscientists and engineers are advancing new technologies to unearth opportunities in critical minerals, carbon storage, and renewable energy. The next generation of geoscientists are more important than any time in human history! Our 2026 RMS-AAPG Organizing Committee has been hard at work curating a technical program of over 60 high quality oral and poster presentations showcasing the talent of professionals and students in our region. Session topics will cover several themes including Oil and Gas in the Rocky Mountain Region, Non-Petroleum Resources and Related Science, Geology of the Rocky Mountain Region, and a special Montana Energy Resources and Geology session. We are fortunate to have Dr. Johnny MacLean, Chancellor of Montana Technological University, open the meeting on Saturday evening following the Icebreaker Reception and Dr. Carlotta Chernoff, Global Chief Geoscientist at ConocoPhillips, who will entertain and inspire on Sunday at the All-Convention Luncheon. A series of exciting field trips to the geologic treasures in and outside Butte will enrich your experience at our conference. We are especially excited to offer several specific events for Students and Young Professionals including a meet-and-greet, job fair, mentoring roundtables, and scientific writing workshop. Lastly, we would like to give a big shout-out to our nearly 40 sponsors and exhibitors whose support make the 2026 RMS-AAPG Annual Meeting possible. Butte and Montana offer a stunning backdrop, rich in beauty and (geologic) history. We are excited to have you join us on the campus of Montana Tech as we gather to discuss past success and evolving technologies. Together we can unearth opportunities that enhance lives and preserve our planet! Michael Hofmann, 2026 RMS-AAPG Meeting Co-Chair Jim Suydam, 2026 RMS-AAPG Meeting Co-Chair

2026 RMS AAPG

i

BUTTE, MT

MONTANA GEOLOGICAL SOCIETY WELCOME LETTER

Greetings everyone and welcome to the 2026 Rocky Mountain sectional meeting of the American Association of Petroleum Geologists. Our organizing committee has been well at work for the majority of this year planning this meeting, and I want to first congratulate them on their amazing work. Many have helped with these efforts, but a big thank you is in order for the conference chairs, Michael Hofmann and Jim Suydam. Our technical program was spearheaded by Marc Buursink and Justin Birdwell, fieldtrips were coordinated by Mary Bitney, and sponsorship and exhibitors were handled by Dave McGee. Bridget Crowther handled event coordination and planning, and a very special thank you is also in order for our Student and Young Professional Events Chair, Chioma Onwumelu. Thanks to all of these people for making this event come to fruition, and thank you to our host, Montana Tech! The Montana Geological Society is proud to again host this sectional meeting, having done so in 2017. Founded in 1949 in Billings, MT, the Montana Geological Society is a non-profit organization. Originally known as the Billings Geological Society, they conducted their first field conference in September 1950 and changed the name to Montana Geological Society in 1966. Seventy-six years after that first field conference, the MGS continues its mission of promoting interest in geology and allied science, and to encourage fellowship and cooperation. We offer summer field trips and a winter speaker series, as well as scholarships and awards to student researchers and Montana science teachers. As a geologist, I cannot think of a more perfect place than Butte to convene this meeting, given the theme of Unearthing Opportunities. I hope as an attendee that you will not only enjoy the conference but also the rich history of Butte. In this way of looking back, we also look forward to new opportunities in the geosciences, and our sessions reflect the burgeoning interest in critical minerals, helium, and hydrogen. And as always, we remain classically grounded in oil and gas and the geology of the Rocky Mountain region. I am especially delighted to see the focus on student events at this year’s meeting, including workshops, roundtables, and the Rocky Mountain Rendezvous job fair. Lastly, we would like to extend our sincere gratitude to all the generous sponsors whose support makes the 2026 RMS-AAPG Annual Meeting possible. At the Little Rocky tier, we recognize Finley & Spade Associates, HIVE Partners, NodalSeismic, Raptor Consulting, and Welter Consulting. At the Big Snowy tier, we thank Geophysical Pursuit Inc. (GSI), Hereford Resources, Hunt Oil Company, Mogotes Energy, ONEGEO, Sage Butte Energy, and WRC Energy. Our Bitterroot sponsors include AIM GeoAnalytics, Ballard Petroleum, Bison Engineering, DIG Geochemistry, FourPoint Energy, MOJO, Neset Consulting, and RR LLC. At the Crazy tier, we extend special appreciation to Elk Range Resources (Poster and Core Sessions Sponsor), GEOLINK (All Convention Luncheon Sponsor), and Crescent Energy. Finally, we offer our deepest thanks to our Beartooth sponsor, Zavanna, for their extraordinary leadership and commitment to advancing our energy community. Cheers everyone, and enjoy the meeting! Sincerely,

Jacob O. Thacker MGS President

2026 RMS AAPG

ii

BUTTE, MT

SPONSORS

THANK YOU TO OUR GENEROUS SPONSORS BEARTOOTH (>$10,000)

CRAZY (>$5,000)

POSTER AND CORE SPONSOR

AlALL CONVENTION LUNCH SPONSORl co 2026 RMS AAPG

iii

BUTTE, MT

SPONSORS

BITTERROOT (>$2,500)

STUDENT EVENT SPONSOR

2026 RMS AAPG

STUDENT EVENT SPONSOR

iv

BUTTE, MT

SPONSORS

BIG SNOWY (>$1,000)

LITTLE ROCKY (>$500)

2026 RMS AAPG

v

BUTTE, MT

ORGANIZING COMMITTEE

ORGANIZING COMMITTEE

Clayton Schultz AAPG RMS President

Michael Hofmann 2026 RMS AAPG Meeting General Co-Chair

Jim Suydam 2026 RMS AAPG Meeting General Co-Chair

Marc Buursink Technical Program Co-Chair

Justin Birdwell Technical Program Co-Chair

Mary Bitney Field Trip Chair

Dave McGee Sponsorship/Exhibit Chair

Chioma Onwumelu Student Event Chair

Jessica Renstrom MGS Marketing Chair

Jacob Thacker MGS President

Bridget Crowther Conference Staff

2026 RMS AAPG

vi

BUTTE, MT

TABLE OF CONTENTS

TABLE OF CONTENTS RMS-AAPG CHAIRS WELCOME LETTER………………………………………………………….. i MGS PRESIDENT WELCOME LETTER …………………………………………………………….. ii THANK YOU TO OUR GENEROUS SPONSORS………………………………………………….. iii ORGANIZING COMMITTEE CHAIRS………………………………………………………………… vi TABLE OF CONTENTS ………………………………………………………………………………….. vii SCHEDULE OF EVENTS………………………………………………………………………………… 1 GENERAL INFORMATION AT-A-GLANCE…………………………………………………………. 3 AFFILIATED SOCIETIES OF THE AAPG – ROCKY MOUNTAIN SECTION………………….. 5 MONTANA GEOLOGICAL SOCIETY ……………………..…………………………………………. 6 ROCKY MOUNTAIN SECTION AAPG – FOUNDATION…………………………………………. 7 MONTANA TECH CAMPUS .…………………………………………………………………………… 8 STUDENT UNION BUILDING …………………………………………………………………………. 9 EXHIBITS……………………………………………………………………………………………………. 10 KEYNOTES…………………………………………………………………………………………………. 11 HAPPY HOUR AND AWARDS…………………………………………………………………………. 13 CORE DISPLAY……………………………………………………………………………………………. 15 STUDENT EVENTS………….……………………………………………………………………………. 16 FIELD TRIPS……………………………………………………………………………………………….. 17 TECHNICAL PROGRAM………………………………………………………………………………… 21 ABSTRACTS………………………………………………………………………………………………… 28 SPEAKER INDEX………………………………………………………………………………………….. 76 JOIN US NEXT YEAR! ………………………………………………………………………… Back Cover

2026 RMS AAPG

vii

BUTTE, MT

SCHEDULE OF EVENTS

SCHEDULE OF EVENTS

Most events are being held at the Montana Technical University Student Union Building abbreviated here as SUB. TIME

8:00 AM – 4:00 PM 8:00 AM – 4:00 PM 12:00 PM – 4:00 PM 12:00 PM – 7:00 PM 5:00 PM – 7:00 PM 5:00 PM – 6:00 PM 6:30 PM – 8:00 PM

TIME

7:30 AM – 5:00 PM 7:30 AM – 5:00 PM 8:00 AM – 5:00 PM 8:00 AM – 7:00 PM 8:30 AM – 9:50 AM 8:30 AM – 9:50 AM 9:50 AM – 10:30 AM 10:30 AM – 11:50 AM 10:30 AM – 11:50 AM 12:00 PM – 1:30 PM 1:40 PM – 3:00 PM 1:40 PM – 3:00 PM 3:00 PM – 3:30 PM 3:30 PM – 4:50 PM 3:30 PM – 4:50 PM 5:00 PM – 7:00 PM

TIME

6:00 AM – 7:00 AM 7:00 AM – 8:00 AM 7:30 AM – 12:00 PM 7:30 AM – 3:00 PM 8:00 AM – 4:00 PM 8:00 AM – 4:00 PM 8:30 AM – 9:50 AM 8:30 AM – 9:50 AM

2026 RMS AAPG

SATURDAY, OCTOBER 24, 2026

ITEM

Pre Conference Field Trips Exhibitor Move In/ Poster Set Up Speaker Ready Room Registration Ice Breaker Student and Young Professionals Meet and Greet Opening Night Welcome and Keynote

ITEM

SUNDAY, OCTOBER 25, 2026

Registration Speaker Ready Room Posters and Core Displays Exhibit Hall New Developments in Unconventionals Geothermal Resources Break Rocky Mountain Petroliferous Basins: Mowry Shale Critical Minerals All Convention Luncheon – Separate Ticket Uinta Basin 1: Green River Formation Sedimentology and Stratigraphy Break Chemical Geology Geochronology and Provenance Evening Reception and Awards Ceremony

ITEM

MONDAY, OCTOBER 26, 2026

GeoRun with RMS-AAPG President Proposal/Resume Writing Workshop for Students Registration Speaker Ready Room Posters and Core Display Exhibit Hall Rocky Mountain Petroliferous Basins: Williston Basin Helium & Hydrogen

1

LOCATION SUB - Copper Lounge SUB – Mountain Con SUB – 2nd Floor SUB – Copper Lounge SUB – Copper Lounge Mining Geology Building, Room 204

LOCATION

SUB – 2nd Floor SUB – Mountain Con SUB – Copper Lounge SUB – Copper Lounge SUB – Big Butte/Highlands SUB – Kelley/Steward SUB – Big Butte/Highlands SUB – Kelley/Steward Lance Leadership Hall SUB – Big Butte/ Highlands SUB – Kelley/Steward SUB – Big Butte/Highlands SUB – Kelley/Steward SUB – Copper Lounge

LOCATION Poore Room SUB – 2nd Floor SUB – Mountain Con SUB – Copper Lounge SUB – Copper Lounge SUB – Big Butte/Highlands SUB – Kelley/Steward

BUTTE, MT

SCHEDULE OF EVENTS 9:50 AM – 10:30 AM 10:30 AM – 11:50 AM 10:30 AM – 11:50 AM 11:50 AM – 1:00 PM 12:00 PM – 1:00 PM 12:00 PM – 1:30 PM 1:10 PM – 2:30 PM 1:10 PM – 2:30 PM 2:30 PM – 3:00 PM 3:00 PM – 4:20 PM 3:00 PM – 4:20 PM

TIME

8:00 AM – 4:00 PM

2026 RMS AAPG

Break Rocky Mountain Petroliferous Basins: Colorado Basins Subsurface Utilization Lunch Student – Mentor Round Table Job Fair for Students Uinta Basin 2: Green River and Paradox Resources Orphan Well and Well Repurposing Break Exploration Methods Montana Energy Resources and Geology

ITEM

TUESDAY, OCTOBER 27, 2026

Post Conference Field Trips

2

SUB – Big Butte/Highlands SUB – Kelley/Steward Poore Room Poore Room SUB – Big Butte/Highlands SUB – Kelley/Steward SUB – Big Butte/Highlands SUB – Kelley/Steward

LOCATION

BUTTE, MT

GENERAL INFORMATION AT- A-GLANCE

GENERAL INFORMATION AT A GLANCE ICEBREAKER RECEPTION STUDENT UNION BUILDING – COPPER LOUNGE

REGISTRATION STUDENT UNION BUILDING – SECOND FLOOR Saturday 12:00 PM - 7:00 PM Sunday 7:30 AM - 5:00 PM Monday 7:30 AM - 12:00 PM

Free with registration badge

Saturday 5:00 PM - 7:00 PM

Separate queues will be set up for advance and onsite registration.

Join us for this annual conference kick-off. Enjoy meeting up with old friends and making new ones, all while browsing the exhibit hall and partaking in some great food and drink.

SPEAKER READY ROOM STUDENT UNION BUILDING – MOUNTAIN CON ROOM

BREAKS STUDENT UNION BUILDING – COPPER LOUNGE

If oral speakers have not already uploaded their presentations, they will be required to check in at the Speaker Ready Room to load their presentations. Speakers can also receive any last-minute instructions in the Speaker Ready Room. Morning speakers will need to check in the preceding day, while afternoon speakers need to check in before 9:00 AM the day of their talk. Practice tables and electrical hook-up for laptops will be available. Poster presenters will likewise find assistance, as well as “emergency” supplies such as tape and Velcro.

Free with registration badge

Sunday Morning Sunday Afternoon Monday Morning Monday Afternoon We’ve built morning and afternoon breaks into the oral sessions to allow for exploration of posters, cores, and exhibitors’ displays. Grab a coffee and head to the exhibit hall for conversations and educational opportunities with our poster sessions.

The Speaker Ready Room will be open: Saturday 12:00 PM - 4:00 PM Sunday 7:30 AM - 5:00 PM Monday 7:30 AM - 3:00 PM

OPENING NIGHT WELCOME AND KEYNOTE MINING GEOLOGY BUILDING, ROOM 204

The Speaker Ready Room will also serve as the place where judges may complete their ballots and deposit them in the box provided.

Sunday 6:30 PM - 8:00 PM Please plan to attend the Welcome which will feature a keynote address by Johnny MacLean. In addition, there will be welcome comments the conference general co-chairs and and brief welcome addresses from MGS, RMS, and AAPG.

EXHIBIT HALL STUDENT UNION BUILDING – COPPER LOUNGE Free with registration badge

ORAL SESSIONS BIG BUTTE/HIGHLANDS & KELLEY STEWARD

Saturday 5:00 PM - 7:00 PM (during the Icebreaker) Sunday 8:00 AM - 6:30 PM Monday 8:00 AM - 4:00 PM

2026 RMS AAPG

Sunday, 8:30 AM – 4:50 PM Monday 8:30 AM – 4:20 PM

3

BUTTE, MT

GENERAL INFORMATION AT- A-GLANCE the Robert J. Weimer Lifetime Contribution Award, the Teacher of the Year Award, the Julie Lefever Memorial Award, the Distinguished Service Award, John D. Haun Landmark Publication Award, and the Outstanding Young Professional Award.

POSTER SESSIONS – PROFESSIONAL AND STUDENT STUDENT UNION BUILDING – COPPER LOUNGE Sunday 8:00 AM – 6:30 PM Tuesday, 8:00 AM – 4:00 PM

CORE DISPLAY MINERAL MUSEUM

CONVENTION LUNCHEON LANCE LEADERSHIP HALL

Monday 1:00 PM – 3:00 PM

Monday, 12:30 PM – 1:15 PM

Historical Core the Anaconda Mine will be available for examination.

Check at the registration desk for any available remaining tickets ($50) or to pay for and pick up reserved tickets.

STUDENT AND YOUNG PROFESSIONALS MEET AND GREET STUDENT UNION BUILDING – COPPER LOUNGE (MEET AT FIREPLACE)

HAPPY HOUR AND AWARDS STUDENT UNION BUILDING – COPPER LOUNGE

Free with registration badge (*attendees are on their own for dinner)

Saturday 5:00 PM - 6:00 PM

Sunday, 5:00 PM – 6:30 PM Enjoy reconnecting with old friends and spending time with your new ones, all while exploring the exhibits hall and delight in some excellent hors d’oeuvres and drink. The highlight will be the presentations of the 2026 RMS awards – the A.I. Levorsen Memorial Award for the best oral technical presentation, the Steve Champlin Memorial Award for the best poster presentation, the Runge Award for best student presentation,

2026 RMS AAPG

STUDENT PROGRAMMING POORE ROOM Monday 7:00 AM - 8:00 AM Monday 12:00 AM – 1:30 PM The student resume and proposals workshop and mentoring sessions.

4

BUTTE, MT

AFFILIATED SOCIETIES OF AAPG ROCKY MOUNTAIN SECTION

AFFILIATED SOCIETIES OF AAPG ROCKY MOUNTAIN SECTION The Rocky Mountain section of the AAPG represents AAPG members residing in Arizona, Colorado, Idaho, Minnesota, Montana, New Mexico (with the exception of the southeast corner), Nevada, North Dakota, South Dakota, Utah and Wyoming. Note: Arizona and Minnesota have no AAPG affiliated societies. The RMS works with its 11 affiliated societies to hold an annual meeting in various locations throughout the Rocky Mountain Region. The section is managed by an Executive Committee composed of Section Officers and representatives from each of the 11 societies. Albuquerque Geological Society Four Corners Geological Society Grand Junction Geological Society Idaho Association of Professional Geologists Montana Geological Society Nevada Petroleum and Geothermal Society New Mexico Geological Society North Dakota Geological Society Rocky Mountain Association of Geologists Utah Geological Association Wyoming Geological Association

2026 RMS AAPG

Albuquerque, NM Durango, CO Grand Junction, CO Boise, ID Billings, MT Reno, NV Socorro, NM Bismark, ND Denver, CO Salt Lake City, UT Casper, WY

5

BUTTE, MT

MONTANA GEOLOGICAL SOCIETY

MONTANA GEOLOGICAL SOCIETY

The Montana Geological Society (MGS) is a non-profit organization founded in 1949 by a group of Billingsarea geoscientists. Through field conferences, continuing education classes, and the publication of guidebooks and symposia, it works to advance geology and its practical application. The Society also hosts luncheon meetings throughout the year, featuring a variety of guest lecturers. Our History The Society began in September 1949, when George Darrow contacted 32 geological societies across the United States to learn how they were organized. His groundwork led to the formation of the Billings Geological Society, which counted 71 members in its first year and held its First Annual Field Conference in September 1950 to explore the sedimentary rock formations of Montana. Growth came quickly. Within five years, membership had passed 250, and the Society was serving the public through guidebooks, directories, scholarship funds, and geology courses at Eastern Montana College. Members also made significant donations to the local library, science fairs, and scout groups. The Society’s logo, a rock hammer and a bison skull, first appeared during these years. By 1960, the Society was hosting the Tenth Annual Rocky Mountain Section meeting, while its Education Committee kept bringing geology to the local public. Some of those talks drew more than 1,500 people. In 1966, the Billings Geological Society became the Montana Geological Society. Since then, it has continued to grow and expand its impact on the community through outreach and the publication of guidebooks and symposia. Our Mission All of this work serves the objective set out in the Society’s bylaws: “To promote interest and research in geology and allied sciences and their practical application, and to encourage fellowship and cooperation among the members.” Interested in joining? Visit mtgeo.org

2026 RMS AAPG

6

BUTTE, MT

ROCKY MOUNTAIN SECTION AAPG FOUNDATION

ROCKY MOUNTAIN SECTION – AAPG FOUNDATION RMS-AAPG Foundation was established in 1986 by the AAPG Rocky Mountain Section for the purpose of making grants to member societies, student chapters, and other geological organizations.

The Foundation seeks to: • • • • •

Advance the Study of Petroleum geology in the Rocky Mountain Region Support the publication and dissemination of geologic research Promote continuing professional education of petroleum geologists Assist the teaching and study of geology in public and private schools and institutions of higher learning Enhance the public’s awareness and appreciation of geology

Since 2011, the RMS Foundation has supported the Rocky Mountain AAPG Student Chapters by granting funds for field trips, guest speakers, and community service projects. Additionally, AAPG Affiliated Societies receive assistance from the RMS Foundation, utilizing grants for conferences, guidebook publications, and field trips. RMS AAPG Members and organizations are encouraged to apply for Foundation funds to augment your programs. See our AAPG RMS Foundation website at www.aapgrms.org/rms-foundation.

2026 RMS AAPG

7

BUTTE, MT

MONTANA TECHNOLOGICAL UNIVERSITY CAMPUS MAP

ο

ο

ο

ο

ο

2026 RMS AAPG

8

Student Union Building: Location of Exhibit Hall, Technical Sessions, Speaker Ready Room and Registration Mining & Geology Building (MG): Location of Room 204 for Opening Night Keynote Address Museum Building: Location of Mineral Museum (3rd Floor) for Monday Core Viewing Frank & Ann Gilmore University Relations Center: Location of the Poore Room for Monday Student Events Student Success Center: Location of Lance Leadership Hall for Convention Luncheon and Keynote * Requires a separate ticket

BUTTE, MT

MONTANA TECHNOLOGICAL UNIVERSITY STUDENT UNION BUILDING

Floor One

Floor Two

2026 RMS AAPG

9

BUTTE, MT

EXHIBIT HALL

Exhibit Hall

1. 2. 3. 4.

One-Geo 5. MoJo Geological 8. Nodal Seismic Raptor Consulting Consulting 9. Neset Rohmtek 6. Revo Chem Sabata 7. Field Geo Services The Montana Geological Society, RMS – AAPG Foundation and Visit Butte are located on the Student Union Building Concourse

2026 RMS AAPG

10

BUTTE, MT

KEYNOTES

Opening Keynote The opening Keynote will be delivered October 24th, 6:30pm following the Icebreaker Reception As the 13th Chancellor of Montana Technological University, Dr. Johnny MacLean brings a breadth of experience to his role. His rich background as a petroleum geologist, environmental scientist, geology professor, and executive administrator provides a powerful blend of industry insight and academic vision for Montana Tech. He is deeply committed to the university’s heritage and its vital role in the Butte–Silver Bow community. Under his leadership, Montana Tech continues its unwavering focus on its mission: preparing the next generation of leaders in STEM, health sciences, and other vital fields. Away from campus, Dr. MacLean and his family enjoy exploring western Montana's mountains and rivers.

Convention Luncheon Keynote The Convention Luncheon Keynote will be delivered October 25th at Noon. This is a separately ticketed event if you would like to attend, please see the registration desk.

“A View from the Chief Geoscientist’s Office Window” Over a nearly 25-year career with ConocoPhillips, Global Chief Geoscientist, Dr. Carlotta Chernoff, has had the privilege of working on a wide variety of subsurface projects across a number of different basins. Along the way, she has learned essential lessons about the importance of Geoscience in helping ensure good business decisions for projects across the E&P lifecycle. Key among those learnings are the value of carrying multiple working hypotheses, the importance of partnering across disciplinary boundaries to create integrated solutions and the ability to tell a good story. She will share some examples from her career that illustrate why Geoscientists need to be prepared for the rocks to yield surprises, the value of a simple cartoon to communicate complex concepts and why you are never too old (or too experienced!) to learn something new.

2026 RMS AAPG

11

BUTTE, MT

KEYNOTES

Biography Dr. Chernoff is Global Chief Geoscientist for ConocoPhillips. Chernoff has 24 years of experience working in oil and gas exploration, appraisal and development opportunities across multiple basins within ConocoPhillips’ US and global assets. She has served in her current role as Global Chief Geoscientist since January 2026, and prior to that she was Global Chief Geologist from February 2023. Chernoff joined Phillips Petroleum as a geologist in Houston, TX in 2002. She has held a variety of technical roles in offshore Brazil, the Gulf of Mexico (GOM), Australia, onshore US Lower 48 and Alaska. Leadership roles spanning across the petroleum lifecycle have included L48 New Ventures Manager screening for new unconventional plays, Project Integration Manager for the nonoperated Shenandoah Discovery (GOM) and Appraisal Manager in Alaska, where she led evaluation of the Willow and Narwhal discoveries. Most recently, Chernoff served as the Greater Kuparuk Area Asset Development Manager in Alaska, and was responsible for delivery of new opportunities and production from the prolific Kuparuk area reservoirs. Chernoff grew up in Houston, Texas, the daughter of Canadian parents. She earned a BS degree in Geophysics and a Masters degree in Geology from The University of Texas at Austin in 1992 and 1995, respectively, and a PhD in Geology from the University of Arizona in 2002. She has served on Advisory Boards at both The University of Texas and the University of Arizona and is a strong advocate for undergraduate research and field experiences in the Geosciences.

2026 RMS AAPG

12

BUTTE, MT

HAPPY HOUR & AWARDS

HAPPY HOUR & AWARDS After the technical session ends on Sunday at 5:00 PM, you are invited to the Copper Lounge for a Happy Hour of socializing, delicious hors d’oeuvres and drinks. The high point of the evening will be honoring the 2026 Rocky Mountain Section award recipients and the presentation of their welldeserved awards.

A.I. LEVORSEN MEMORIAL AWARD FOR THE BEST ORAL PRESENTATION

STEVE CHAMPLIN MEMORIAL AWARD FOR THE BEST POSTER PRESENTATION

Since 1966 the A.I. Levorsen Memorial Award is awarded annually for the best oral presentation at the AAPG Rocky Mountain Section meeting. During selection, emphasis is placed on original thinking and new ideas in exploration. Many people and societies contributed to make this annual award possible. A gift from Bob Levorsen, son of A.I. Levorsen, allowed plaque award improvements. The award is given at no cost to the host society.

Steve Champlin Memorial Award for the best poster presentation at the AAPG Rocky Mountain Section meeting has been awarded annually since 1985. The award is sponsored by Wyoming Geological. Association at no cost to the host society. A Steve Champlin memorial Petroleum Geology scholarship is also awarded annually by the Wyoming Geological Association.

A.I. Levorsen (1894–1965) was born and educated in Minnesota and spent most of his career in Oklahoma. He worked for four oil companies, was a consulting geologist, then chairman and dean of the School of Mineral Sciences at Stanford University. He was past president of AAPG, GSA and AGI. He was awarded honorary doctorates from the Colorado School of Mines, and his alma mater, the University of Minnesota. Levorsen was highly sought as a speaker due to his enthusiasm and ability to stimulate thought about new ways to find petroleum.

Steve Champlin was born and raised in Enid, Oklahoma and played football for the University of Oklahoma. He received B.S. and M.S. degrees in Geology and served in the U.S. Army. He worked for Texaco and Tenneco, moving to Casper, Wyoming in 1963 and becoming an independent geologist in 1966. Steve cofounded Echo Oil Co. (merged with Maynard Oil Co.) and Rainbow Resources (merged with Williams Inc.). Steve was a major stockholder or board member of several other oil companies, and on the board of numerous professional and civic organizations. Steve died in 1985 at the young age of 51.

2026 A.I. LEVORSEN AWARD – BEST ORAL PRESENTATION

2026 STEVE CHAMPLIN MEMORIAL AWARD – BEST POSTER PRESENTATION

ZANE JOBE, COLORADO SCHOOL OF MINES ULTRA-HIGH RESOLUTION CORE CHARACTERIZATION LEADS TO BETTER CONSTRAINTS ON VERTICAL AND LATERAL HETEROGENEITY IN SUBSURFACE RESERVOIRS

TIMOTHY NESHEIM, WB GEOLOGICAL CONSULTING RENEWED EXPLORATION IN THE RED RIVER FORMATION (WILLISTON BASIN) USING 3-D SEISMIC

2026 RMS AAPG

13

BUTTE, MT

HAPPY HOUR & AWARDS

ROBERT J. WEIMER LIFETIME CONTRIBUTION AWARD

2026 DISTINGUISHED SERVICE AWARD

The Robert J. Weimer Lifetime Contribution Award recognizes contributions to the practice of the geosciences and/or petroleum geology in the region of the Rocky Mountains. This award was first given in 2013. The Lifetime Contributions Award is similar to the national AAPG Sidney Powers Memorial Award, the AAPG’s most distinguished award.

TIMOTHY NESHEIM, WB GEOLOGICAL CONSULTING

JOHN D. HAUN LANDMARK PUBLICATION AWARD Rocky Mountain Landmark Publication Award was first given in 2013 to recognize the authors or editors of a book, guidebook or other publication that over the past decade has had exceptional influence on developing new hydrocarbon plays or deeper understanding of fundamental geology within the Rocky Mountain region.

2026 ROBERT J. WEIMER LIFETIME CONTRIBUTION AWARD PETER BUCKNAM

JULIE LEFEVER MEMORIAL AWARD

2026 JOHN D. HAUN LANDMARK PUBLICATION AWARD

Since its establishment in 2017, the AAPG Rocky Mountain Section has approved the creation of the annual Julie Lefever Memorial Award in recognition of those who have done an exceptional job at sharing geoscience knowledge with the science community and/or general public. The Inaugural award was granted to Richard and Julie for their countless hours they put in over the years helping spread geoscience knowledge through research and teaching. Through their combined efforts, countless people have benefited from their selfless willingness to teach others.

JOHN METESH & SUSAN M. VUKE GEOLOGY OF MONTANA MONTANA BUREAU OF MINES AND GEOLOGY SPECIAL PUBLICATION 122, 2020

OUTSTANDING YOUNG PROFESSIONAL AWARD The Outstanding Young Professional Award is presented to a person with less than five years of experience who has made significant contributions to the industry through volunteering to the AAPG, the AAPG Rocky Mountain Section, or an AAPG Rocky Mountain Section affiliated society or by scientific achievement including publication, presentation, or other contributions to geology. This award was first presented in 2015.

2026 JULIE LEFEVER MEMORIAL AWARD RILEY BRINKERHOFF, HIVE PARTNERS

DISTINGUISHED SERVICE AWARD

2026 OUTSTANDING YOUNG PROFESSIONAL

The Distinguished Service Award is presented to members who have distinguished themselves in singular and beneficial longterm service to AAPG Rocky Mountain Section, with emphasis on long-term and at the same time, meaningful service to the Association.

2026 RMS AAPG

JACOB THACKER

14

BUTTE, MT

SPECIAL CORE DISPLAY

SPECIAL CORE DISPLAY

ANACONDA RESEARCH COLLECTION Presenter: Kyle Eastman

Hand samples and historic drill core samples from the Anaconda Research Collection will be made available for viewing at the Montana Tech Mineral Museum. These samples are representative of the types of mineralization and hydrothermal alteration in the Butte District, and include historic vein material from underground mines and the Berkeley Pit, porphyry Cu-Mo samples from the Continental Pit, and drill core samples from deep drilling in the 1970s-1980s. The International Commission on Geoheritage recently recognized the Anaconda Research Collection as a GeoCollection, and this collection is managed by the Montana Bureau of Mines and Geology. Session: Monday Ocotber 25, 1-3 PM Location: Mineral Museum

2026 RMS AAPG

15

BUTTE, MT

STUDENT EVENTS

STUDENT EVENTS STUDENT AND YOUNG PROFESSIONALS MEET AND GREET

Saturday October 24, 5-6 PM • Exhibit Hall – Copper Lounge (Meet By The Fire Place) On the first night of the conference, after checking in with registration, head to the Exhibit Hall in Copper Lounge. At the fireplace, meet the other students and young professionals taking part in the 2026 RMS-AAPG Meeting. Use this opportunity to connect with your peers and meet the professionals attending before heading over to the opening night keynote.

PROPOSAL/RESUME WRITING WORKSHOP FOR STUDENT Monday October 26, 7-8 AM • Poore Room

Join Dr. Behnaz Hosseini for a resume and proposal writing workshop where you’ll learn the essential techniques for crafting compelling proposals and polished resumes. Whether you are seeking funding, or your next career opportunity, you will leave with practical tips and tools to present yourself and your work with confidence.

MENTOR ROUND TABLE AND JOB FAIR

Monday October 26, 12-1:30 PM • Poore Room Join us for a student mentorship roundtable, where small groups of five to six students will be paired with an experienced professional mentor in an intimate, conversational setting. This is a great opportunity to ask questions, gain insight into different career paths, and receive practical advice from someone working in the field. Whether you’re exploring your options or looking to build your professional network, you’ll leave with valuable guidance and new connections. Lunch will be provided, so come ready to eat, engage, and learn.

2026 RMS AAPG

16

BUTTE, MT

FIELD TRIPS

FIELD TRIPS PRE-CONFERENCE FIELD TRIPS “Critical Minerals from Sea Bug Corpses” Leaders: Professor Adrian Van Rythoven (MBMB) and Prof. Marc Hendrix (University of Montana) Date & Time: Saturday, October 24, 2026, 8:00 am to 3:00 pm Logistics: Field Trip departs from and returns to Montana Tech campus. To make this trip possible, we're asking for volunteer drivers. If you're able to drive, please let us know, as your help is greatly appreciated! We also ask that all attendees be willing to carpool so we can keep the number of vehicles to a minimum. Lunch will be provided, so there's no need to pack one. Costs: Professionals $50/ Students $20

Highlights: This field trip shows correlations between trace element concentrations and depositional environments. The Permian age Phosphoria Formation, found in Montana, Idaho, Utah and Wyoming, was deposited during marine transgressive-recessive cycles in a foreland basin during the assembly of the Pangean continent. The Retort and Meade Park members contain high phosphate and hydrocarbon content of the formation. At the depositional margins of the Retort depocenter, very well-sorted ore grade peloidal phosphorite is present. Elevated levels of cadmium, chromium, copper, fluorine, molybdenum, nickel, rare earth elements (REE), selenium, uranium, vanadium, and zinc were also found in peloidal phosphorite. The exceptionally high

2026 RMS AAPG

17

BUTTE, MT

FIELD TRIPS concentrations of metals have been interpreted to reflect fundamental transitions from anoxic to oxic marine conditions. Phosphoria Formation was historically mined in Montana for phosphorous until the 1990s. In the 1950s and 60s, the formation was also evaluated for vanadium and uranium. With recent economic and political pressures for domestic rare earth elements (REE), the Phosphoria has received another look as a potential resource. REE mineralization in the Phosphoria has been noted historically, but with recent economic and political pressures for domestic REE production, a deeper understanding of how the depositional environment impacts the location and quantities of REE mineralization has become a priority. This field trip consists of a trip to the former Edgar Mine, a source of peloidal phosphorite, located south of Drummond. At the mine site, samples from the Retort member obtained from other abandoned or reclaimed mines from southwestern Montana will be provided for viewing, along with their assay results and description of their lithologies. This information is to demonstrate that lithologies and assay results can be used as a method in determining whether economic REE production is realistic. The samples used in this trip are discussed in the Montana Bureau of Mines and Geology Special Publication 124.

“Fault, Fold, and Cleavage Duplexes of Sandy Hollow” Leaders: Stuart Parker (MBMG), Steven E Boyer* *Co-author of Field Guide; not in attendance Date & Time: Saturday, October 24, 2026, 8:00 am to 3:00 pm Logistics: Field Trip departs from and returns to Montana Tech campus. To make this trip possible, we're asking for volunteer drivers. If you're able to drive, please let us know, as your help is greatly appreciated! We also ask that all attendees be willing to carpool so we can keep the number of vehicles to a minimum. Lunch will be provided, so there's no need to pack one. Costs: Professionals $50/Students $20

2026 RMS AAPG

18

BUTTE, MT

FIELD TRIPS Highlights: The incredible exposures of folded and faulted rocks within Sandy Hollow, located about 50 miles south of Butte, have long been used by structural geologists as analogs for the structures that characterize thin-skinned fold-thrust belts around the world. Understanding the geometry and deformation mechanisms associated with folds and faults is crucial when assessing hydrocarbon potential in these tectonic settings. The series of fault-propagation folds and associated thrust faults observed around Sandy Hollow are structural analogs to what occurs at depth within many oil and gas fields in foreland settings. On this field trip we will focus on the outcrop to meso-scale duplexes that commonly occur within these larger fault-propagation folds and thrust faults, in an attempt to gain a better geometric understanding of smaller-scale, more distributed deformation zones that may not be directly visible on seismic surveys. The field trip will highlight the wide array of deformation mechanisms that operate within duplexes, which may include faulting, folding, or pressure solution (cleavage). Field examples of fault, fold, and cleavage duplexes will be used to demonstrate how porosity and permeability may be either created or destroyed during progressive deformation. Understanding how strain evolved within these common but small-scale structures allows for detailed inferences to be made regarding porosity and permeability within larger potential hydrocarbon targets, specifically in anticlines above faultpropagation folds like those on display in Sandy Hollow.

POST-CONFERENCE FIELD TRIPS

The post-conference field trips consist of two tours local to Butte, MT. You can attend one or the other, or both at your discretion. Costs: - One tour $25, both $60 (Full Day includes lunch) Notes: • • •

In case of inclement weather, this tour will be cancelled. Steel toed shoes/boots and hard hats are required for touring the Continental Pit mine. It is possible that Montana Resources has hard hats to borrow for the tour.

“Continental Pit Mine and Mill Tour” Date & Time: Tuesday, October 27, 2026, 8:30 am to 11:30 am The Continental Pit field trip, scheduled for Tuesday, October 27 from 8:30 – 11:30 am, visits Montana Resources current mining operations. The mine area consists of a thick leached cap and overburden, 160 to 200 feet, draped over a massive copper-molybdenum orebody bounded on the west by the Continental Fault and on the east by the Klepper Fault. Continental Primary Zone copper occurs as chalcopyrite in interlacing veinlet swarms and as disseminations in the Butte Quartz Monzonite while Continental Primary Zone molybdenum occurs in younger subparallel veinlet swarms and slicks that offset the early copper veinlets. Participants will be able to examine oxidized, supergene, and hypogene ores in situ. The tour covers the mining process from drilling and assaying cores through extracting the metal sulfides in flotation cells. The extracted metal sulfide concentrates are then transported to offsite roasting facilities or smelters for final processing.

2026 RMS AAPG

19

BUTTE, MT

FIELD TRIPS “Water Management Tour” Date & Time: Tuesday, October 27, 2026, 1:00 pm to 3:00 pm After visiting Montana Resources permitted copper and molybdenum mine and concentrator in the morning, we will turn to the Superfund cleanup of legacy mining from a perch overlooking the Berkeley Pit, the Continental Pit, the concentrator and the 700+ foot high Yankee Doodle Tailings impoundment after lunch, from 1 – 3 pm. The origins of the ore and subsequent contamination for the entire Superfund complex, including the Anaconda Smelter and Clark Fork/Mill Town Sediments Sites, are the 10,000 miles of underground workings and the Berkeley Pit with its infamous lake. Underground mining was going full bore by the 1880s but was largely abandoned as the rich copper veins played out and open pit mining proved more economical to extract lower grade ore in the later 1950s. In 1982, Atlantic Richfield, the mine owner, turned off the pumps that kept groundwater out of the Berkeley Pit and underground workings. By 1987, when EPA established the Butte Mine Flooding Operable Unit, the Berkeley Pit had a small but rapidly rising lake that was fed by groundwater flowing through the surrounding underground mine workings. The EPA determined that cleaning up contamination in the rising water would be technically impracticable, but that the contamination could be managed by keeping water levels below an elevation that would contain it within the mining area, a “protective water level” at 5410 feet above sea level. Water levels are currently being maintained well below that mark by pumping and treating and then releasing the treated water into Silver Bow Creek. A working group of local, state and federal personnel, plus local citizens, has created an informative website called Pitwatch (https://pitwatch.org/learn/water-treatment/).

2026 RMS AAPG

20

BUTTE, MT

TECHNICAL PROGRAM

2026 AAPG ROCKY MOUNTAIN SECTION MEETING TECHNICAL PROGRAM SATURDAY, OCTOBER 24, 2026 OPENING KEY NOTE 6:30 PM – 6:45PM 6:45 PM – 8:00 PM

MINING GEOLOGY BUILDING, ROOM 204 WELCOME FROM RMS-AAPG, AAPG, AND MGS OPENING KEY NOTE Johnny MacLean, Chancellor of Montana Technological University

SUNDAY, OCTOBER 25, 2026 NEW DEVELOPMENTS IN UNCONVENTIONALS 8:30 AM – 8:35 AM 8:35 AM – 9:00 AM 9:00 AM – 9:25 AM 9:25 AM – 9:50 AM

ROOM 1 – BIG BUTTE/HIGHLANDS

SESSION INTRODUCTION Session Chairs: Samuel Hudson & TBD Novel Geochemical Methods for Sweet Spot Location and Quantitation of Mobile Oil in Tight, Unconventional Rocks Henry Halpern, StratoChem Services Anthropogenic Tracers in Normandy and Saipan: Modern Coastal Processes and Implications for the Cretaceous Interior Seaway Kassandra I. Ramirez, Brigham Young Univeristy Western Powder River Basin Niobrara Performance and Potential: Uplift from Managed Drawdown Optimization, and Niobrara "C" Wine-Racking Rex Stout, Sage Butte Energy LLC

GEOTHERMAL RESOURCES 8:30 AM – 8:35 AM 8:35 AM – 9:00 AM

9:00 AM – 9:25 AM 9:25 AM – 9:50 AM

ROOM 2 – KELLEY/STEWARD

SESSION INTRODUCTION Session Chairs: Justin Birdwell & TBD Modeling geothermal resource potential in sedimentary basins of the Rocky Mountain Region Justin Birdwell, U.S. Geological Survey, Central Energy Resources Science Center Geothermal Resource Assessment of Montana for Enhanced Geothermal Systems (EGS) Power Production Ryan C. Davison, MBMG Reservoir Thermal Energy Storage in Extensional Environments: Insights from National Assessment Efforts Jeff D. Pepin, U.S. Geological Survey, Central Energy Resources Science Center

9:50 AM – 10:30 AM

2026 RMS AAPG

BREAK

21

BUTTE, MT

TECHNICAL PROGRAM ROCKY MOUNTAIN PETROLIFEROUS BASINS: MOWRY SHALE 10:30 AM – 10:35 AM 10:35 AM – 11:00 AM 11:00 AM – 11:25 AM

11:25 AM – 11:50 AM

ROOM 1 – BIG BUTTE/HIGHLANDS

SESSION INTRODUCTION Session Chairs: Samuel Hudson & TBD Proximal-to-Distal Facies Trends and Laramide Tectonic influence in the Mowry Shale, Greater Green River Basin, Wyoming Brent Greenhalgh, Wexpro Company Organofacies Variability of the Mowry Shale Across the Green River and Wind River Basins: A Large Pyrolysis Dataset from Core, Cuttings and Outcrop Samuel M. Hudson, Brigham Young University Mowry Shale Geology, Sweet Spot Delineation, and Production Evaluation in the Powder River Basin, Wyoming Matthew B. Johnson, School of Energy Resources, University of Wyoming

CRITICAL MINERALS

ROOM 2 – KELLEY/STEWARD

10:30 AM – 10:35 AM

SESSION INTRODUCTION Session Chairs: Justin Birdwell & TBD Machine Learning-Based Gold Prospectivity Mapping in the Yilgarn Craton, Western Australia Kayla J. Fields, Radford University Elemental geochemistry of produced waters from oil and gas wells, Uinta and Paradox Basins, Utah Ryan Gall, Utah Geological Survey Appraisal of a Super-Giant Sodium, Lithium, Boron, and Tungsten Salt Complex in Central Nevada Vincent Ramirez, 3PL Operating Inc.

10:35 AM – 11:00 AM 11:00 AM – 11:25 AM 11:25 AM – 11:50 AM

11:50 AM – 1:30 PM

LUNCH BREAK

ALL CONVENTION LUNCH 12:00 PM – 1:00 PM

LANCE LEADERSHIP HALL

A View from the Chief Geoscientist’s Office Window Carlotta Chernoff, Conoco Phillips

UINTA BASIN 1: GREEN RIVER FORMATION 1:40 PM – 1:45 PM 1:45 PM – 2:10 PM 2:10 PM – 2:35 PM 2:35 PM – 3:00 PM

2026 RMS AAPG

ROOM 1 – BIG BUTTE/HIGHLANDS

SESSION INTRODUCTION Session Chairs: Riley Brinkerhoff & TBD Pushing the Uteland Butte Play to its Economic Edges, the Green River Formation, Uinta Basin, Utah Riley Brinkerhoff, HIVE Partners Maximizing Uinta Basin (Utah, USA) Oil Yield Through Geochemical Fingerprinting of Produced Water Troy Day, Brighman Young University Capturing Stranded Reserves in the Prolific Uinta Basin: Leveraging Favorable Geology with 15,000-ft J-Shaped Laterals Kalen Smith, FourPoint Energy

22

BUTTE, MT

TECHNICAL PROGRAM SEDIMENTOLOGY AND STRATIGRAPHY 1:40 PM – 1:45 PM 1:45 PM – 2:10 PM 2:10 PM – 2:35 PM 2:35 PM – 3:00 PM

ROOM 2 – KELLEY/STEWARD

SESSION INTRODUCTION Session Chairs: TBD Fluvial Compound Architectural Element Organization in the High Net-toGross Hawkesbury Sandstone Brad Taylor, Brigham Young University Quantifying Order in Fluvial Architecture: A Spatial Statistics Approach to Autogenic vs. Allogenic Controls on Channelform Organization Olivia J. Tatum, Brigham Young University Contrasting Contemporaneous Depositional Systems in the Maastrichtian Lewis Shale: Washakie Basin, Cherokee Ridge, and Sand Wash Basin, Greater Green River Basin Mark M. Nell, Wexpro Company

3:00 PM – 3:30 PM

BREAK

CHEMICAL GEOLOGY 3:30 PM – 3:35 PM 3:35 PM – 4:00 PM

4:00 PM – 4:25 PM

4:25 PM – 4:50 PM

ROOM 1 – BIG BUTTE/HIGHLANDS SESSION INTRODUCTION Session Chairs: Justin Birdwell & TBD Assessing Potential CO2 Storage in Frontier 2nd Sand and Muddy at a Wyoming Site by Analyzing Volatile Subsurface Fluids in Unpreserved Wet Cuttings Christopher Smith, Advanced Hydrocarbon Stratigraphy Chemostratigraphy of the Late Cretaceous Mancos Shale, western Colorado Justin Birdwell, U.S. Geological Survey, Central Energy Resources Science Center The Portable ED-XRF Experience: Consistency, Accuracy, and the World of Make Believe Milly Wright, Rohmtek

GEOCHRONOLOGY AND PROVENANCE 3:30 PM – 3:35 PM 3:35 PM – 4:00 PM 4:00 PM – 4:25 PM

4:25 PM – 4:50 PM

2026 RMS AAPG

ROOM 2 – KELLEY/STEWARD

SESSION INTRODUCTION Session Chairs: Michael Hofmann & TBD The Black Hills as a source of quartz for the Turonian Turner Sanstone in the Powder River Basin Michael H. Hofmann, AIM GeoAnalytics Insights into paleogeography and depositional characteristics atop the Great Unconformity in Western Montana, USA: Zircon U-Pb-Hf and monazite U-Pb constraints from the Cambrian Flathead Sandstone Joseph R. Moll, Department of Earth Sciences, Montana State University Tracing Drainage Reorganization During Sevier Orogenesis Using Detrital Zircon Provenance and XRF Geochemistry Julie Robinson, Department of Geological Sciences, Brigham Young University

23

BUTTE, MT

TECHNICAL PROGRAM

MONDAY OCTOBER 26, 2026 ROOM 1 – BIG BUTTE/HIGHLANDS

ROCKY MOUNTAIN PETROLIFEROUS BASINS: WILISTON BASIN 8:30 AM – 8:35 AM 8:35 AM – 9:00 AM 9:00 AM – 9:25 AM 9:25 AM – 9:50 AM

SESSION INTRODUCTION Session Chairs: Stephen Sonnenberg & TBD The Williston Basin's take on Late Devonian continental margin tectonism Michael H. Hoffman, AIM GeoAnalytics Evolution and Expansion of the Bakken-Three Forks Hydrocarbon Play Timothy Nesheim, WB Geological Conulting LLC Stratigraphic Patterns of Siliciclastics within Visean Mixed CarbonateSiliciclastic Strata, Mission Canyon Formation, Northern Williston Basin Carson Renaud, ROK Resources

HELIUM AND HYDROGEN 8:30 AM – 8:35 AM 8:35 AM – 9:00 AM

9:00 AM – 9:25 AM 9:25 AM – 9:50 AM

ROOM 2 – KELLEY/STEWARD

SESSION INTRODUCTION Session Chairs: Marc Buursink & Justin Birdwell Potential for the recovery of hydrogen from organic-rich Green River oil shales in Piceance Basin, CO Justin Birdwell, U.S. Geological Survey, Central Energy Resources Science Center Scanning Earth's Helium Exhaust: Digital Geochemistry as a Pre-Seismic Screening Tool for Charged Petroleum, Helium, and Geothermal Systems Dion Lobreau, Pahvant Resources Origin, reservoir development and intrusive igneous control of a Devonian carbonate helium accumulation in the Utopia Field, northern Montana Henry Williams, Thor Resources Inc.

9:50 AM – 10:30 AM

BREAK

ROCKY MOUNTAIN PETROLIFEROUS BASINS: COLORADO BASINS

ROOM 1 – BIG BUTTE/HIGHLANDS

10:30 AM – 10:35 AM

SESSION INTRODUCTION Session Chairs: Stephen Sonnenberg & TBD

10:35 AM – 11:00 AM

Mapping sedimentary lithofacies at 1:24,000 scale in the Maastrichtian Hell Creek Formation, southwestern Garfield County, Montana Marc Hendrix, Department of Geosciences, Univeristy of Montana Integrating 100 Years of Research in the Mesaverde Group, Piceance Basin, Colorado, USA Bryan P. McDowell, Colorado School of Mines & Sabata Energy Consultants Loveland Oil Field, a Laramide Structural Anticlinal Trap, Denver Basin, Colorado Stephen Sonnenberg, Colorado School of Mines

11:00 AM – 11:25 AM 11:25 AM – 11:50 AM

SUBSURFACE UTILIZATION 10:30 AM – 10:35 AM

2026 RMS AAPG

ROOM 2 – KELLEY/STEWARD

SESSION INTRODUCTION Session Chairs: Marc Buursink & TBD

24

BUTTE, MT

TECHNICAL PROGRAM 10:35 AM – 11:00 AM 11:00 AM – 11:25 AM 11:25 AM – 11:50 AM

Subsurface Systems Modeling: From Petroleum to New Energy and Mineral Systems Zachary F.M. Burton, Montana State University Introducing a Quantitative and Probabilistic Methodology for Evaluating Natural Gas Storage Capacity in Depleted Hydrocarbon Reservoirs Marc Buursink, U.S. Geological Survey Balancing Accuracy and Scalability in Porosity Estimation for Regional Multi-Resource Assessments Jenny LaGesse, U.S. Geological Survey, Central Energy Resources Science Center

11:50 AM – 1:00 PM

LUNCH BREAK

UINTA BASIN 2: GREEN RIVER AND PARADOX RESOURCES 1:10 PM – 1:15 PM 1:15 PM – 1:40 PM 1:40 PM – 2:05 PM

2:05 PM – 2:30 PM

ROOM 1 – BIG BUTTE/HIGHLANDS

SESSION INTRODUCTION Session Chairs: J. Paul Matheny & TBD A Deformation Mechanism for the Duchesne Fault Zone and its Impacts on the Uinta Basin Horizontal Oil Play Riley Brinkerhoff, HIVE Partners White Canyon Bank - An Extensive, Previously Oil-Saturated Pennsylvanian Oolite Deposit in the Western Paradox Basin, Southeastern Utah J. Paul Matheny, Consulting Geologist A Tangible and Viable Source for the Tar Sand Triangle, Western Paradox Basin, southeastern Utah J. Paul Matheny, Consulting Geologist

ORPHAN WELL AND WELL REPURPOSING 1:10 PM – 1:15 PM 1:15 PM – 1:40 PM

1:40 PM – 2:05 PM 2:05 PM – 2:30 PM

ROOM 2 – KELLEY/STEWARD

SESSION INTRODUCTION Session Chairs: Todd Hoffman & TBD How Do Meteorological Conditions Impact Leaking Orphan Wells in Montana? Nicholas Gianoutsos, U.S. Geological Survey, Central Energy Resources Science Center Plugging Montana’s First Oil Well, the Butte Oil #1, Located in Glacier National Park David Reichardt, Montana Techinlogical University From Oil and Gas to CCUS: An Interactive Web Application for Carbon Sequestration and Subsurface Energy Exploration Gabriela A.E. St. Pierre, Utah Geological Survey

2:30 PM – 3:00 PM

BREAK

EXPLORATION METHODS

ROOM 1 – BIG BUTTE/HIGHLANDS

3:00 PM – 3:05 PM

SESSION INTRODUCTION Session Chairs: Grace Taiwo

2026 RMS AAPG

25

BUTTE, MT

TECHNICAL PROGRAM 3:05 PM – 3:30 PM

3:30 PM – 3:55 PM

3:55 PM – 4:20 PM

Frontier Formation Prospectivity in the Southwest Powder River Basin: Integration of 3D Seismic Inversion, Core-Constrained Sequence Stratigraphy, and Machine Learning Reservoir Characterization Tanya L. Inks, IS Interpretation Services LLC Geochemical Mapping of the California River Protodelta Using HighResolution XRF from Horizontal Wells: Greater Monument Butte Unit, Uinta Basin Travis Moreland, Scout Energy Partners Utilization and Practical Application of Rock Based Measurements in Formation Evaluation of Standard Geophysical Logs in a Complex Fluid/Rock System. Christopher Yokoyama, GeoMark Research

MONTANA ENERGY RESOURCES AND GEOLOGY 3:00 PM – 3:05 PM 3:05 PM – 3:30 PM 3:30 PM – 3:55 PM 3:55 PM – 4:20 PM

ROOM 2 – KELLEY/STEWARD

SESSION INTRODUCTION Session Chairs: Kallie Moore New sedimentologic and geochronologic results from Paleogene lacustrine strata at Beaver Creek, west-central Montana Kallie Moore, University of Montana Paleontology Center Polymetallic potential, including critical elements, of the Philipsburg mining district, Granite County, Montana. Celine M. Beaucamp, Montana Technological University Gravity Faulting and Biogenic Gas Traps along the Highline St Joe Road Field; A Niobrara Fault Gouge Trap Hill County, Montana Mark S. Caldwell, Northshore Energy LLC

ALL MEETING POSTERST

EXHIBIT HALL – COPPER LOUNGE

Session Chairs: Stuart Parker & Chioma Onwumelu Geologic Map of the Metzel Ranch and Ruby Dam 7.5’ Quadrangles, southwestern Montana Daniel T, Brennan, Montana Bureau of Mines and Geology Fluvial Sandstones of the Maastrichtian Hell Creek Formation in Southwestern Garfield County, Montana Reece Holzer, Department of Geosciences, University of Montana Multiscale Fracture Characterization and Compressional Tectonic Controls in the Niobrara Formation, B-Chalk Member, Redtail Field, DJ Basin, Colorado Ceyhan Sahinkaya Akyol, Colorado School of Mines Preliminary Evidence for Basement Structural Inheritance Controls on Fracture Development and Hydrocarbon Migration in the North Park Basin, Colorado Victoria I Simoneau, Colorado School of Mines Organic Carbon Distribution in Submarine Depositional Systems of the Lewis Shale, Greater Green River Basin, Wyoming Jutamas Charoensuk, Colorado School of Mines Geochemistry and Sedimentology of the Upper Castle Peak and Long Point Members of the Green River Formation, Uinta Basin, UT Amelia Fullwood, University of Montana

2026 RMS AAPG

26

BUTTE, MT

TECHNICAL PROGRAM Bakken equivalent shales along the Cedar Creek Anticline, Montana Gary C. Hughes, Montana Bureau of Mines and Geology Hydrocarbon Potential and Organofacies of the Mowry Shale: Integrating Elemental Geochemistry with Pyrolysis Charles W. Kewish, Brigham Young University New geologic mapping in the Plains, Montana area: Stratigraphic and structural findings in the central Belt basin Stuart D. Parker, Montana Bureau of Mines and Geology Perforation Geometry Uniformity as a Physics-Based Indicator of Cluster-Level Fluid Distribution in Multistage Hydraulic Fracturing Fatemeh Saberi, Department of Energy and Petroleum Engineering, University of North Dakota Beyond Tmax: Reassessing Mowry Shale Maturity Through Regional Kinetic Modeling Austin D. Toner, Brigham Young University Core of the Core. Expanding the productive “core” of the Parkman Sandstone through detailed core analysis and application to horizontal targeting and well performance • Includes Core Andrew M. Hennes, Rockies Resources, LLC Rare Earth Element and Yttrium Enrichment and Mineralogical Controls in the Phosphoria Formation and Mowry Shale, Wyoming Djihane Gourari, Richard and Marilyn Lynch Multidisciplinary Advanced Stimulation Laboratory, Department of Energy and Petroleum Engineering, University of Wyoming Supporting Critical Minerals Workforce Development Through Undergraduate Coursework in Mineralogy and Igneous and Metamorphic Petrology Kate Hicks, Minot State University Copper Cliff Gold-Rich Porphyry Copper Occurrence • Including Core Peter C. Ellsworth, Mogotes Metals Inc.

2026 RMS AAPG

27

BUTTE, MT

ABSTRACTS

ABSTRACTS resolution that is impractical through traditional field mapping alone (Bemis et al., 2014; Westoby et al., 2012). Furthermore, subsurface fracture patterns from borehole formation microresistivity images (FMI) and core samples are examined to determine fracture orientations and densities. The integration of these data with drone-based surface mapping facilitates for validation and refinement of fracture models, contributing knowledge to the vertical continuity of fracture networks (Snee and Zoback, 2019). Additionally, stable isotope analyses of calcite fill within fractures are performed to reconstruct the thermal and geochemical conditions during fracture formation and to establish a chronology of fluid migration events (Goldstein and Reynolds, 1994).

MULTISCALE FRACTURE CHARACTERIZATION AND COMPRESSIONAL TECTONIC CONTROLS IN THE NIOBRARA FORMATION, B-CHALK MEMBER, REDTAIL FIELD, DJ BASIN, COLORADO Presenter: Akyol, Ceyhan Sahinkaya (Colorado School of Mines) Co-authors: Stephen A. Sonnenberg (Colorado School of Mines) The Redtail Field, located in the northern part of the Denver-Julesburg (DJ) Basin, is a significant hydrocarbon production area that yields approximately 6.6 million barrels of oil equivalent per day from the Upper Cretaceous Niobrara Formation and the Codell Sandstone. It has been shaped by compressional patterns associated with the Laramide Orogeny (Sonnenberg and Weimer, 2016). Regarding presence and orientation of natural fractures within these formations have significant effects on fluid migration, reservoir performance, and well productivity. (Erslev, 1986). Despite that, variations in fracture orientations and the absence of consistent measurements breeds notable difficulties in the prediction and modelling of fracture-controlled permeability pathways.

Previous researchers presented significant shortwavelength rotations in the maximum horizontal stress (Shmax) orientation across the DJ Basin, with approximately 90° C changes over distances of only a few kilometres (Snee and Zoback, 2019). This variation in orientation promotes the hypothesis that the effect of local structural components, for instance; proximity to fault and fold geometry, highly contribute to fracture orientations. When numerous surface fracture sets are correlated with subsurface borehole data, alignment between them validates the potential for using outcrop analogy to infer subsurface patterns.

This study combines drone-based surface fracture mapping with subsurface data from well logs and core analyses, alongside microstructural and geochemical analyses, to understand deeply and better characterize the fracture systems in the study area to improve the predictive accuracy of geological models.

Isotope results suggest that fracture fills formed under varying thermal regimes, indicating a complex diagenetic history consistent with basin evolution models. In core samples, fractures in the chalk-rich intervals of the Niobrara Formation show higher frequency and greater connectivity compared to marl-dominated sections (Landon et al., 2001).

In this research, based on a multi-faceted methodology, remote sensing, field mapping, core analysis, and geochemical techniques are combined. High-resolution drones are used to survey outcrops which include significant fracture sets in the research area to produce orthomosaics and 3D digital outcrop models. These models expedite the determination and characterization of fracture sets in terms of spacing, continuity, and connectivity along with enabling quantification of surface fracture characteristics at a scale and

2026 RMS AAPG

The findings of integration between fracture mapping with subsurface well data and laboratory analyses provide a comprehensive approach to fracture characterization in the Niobrara B Chalk and support the idea that fracture patterns are primarily controlled by compressional tectonic in

28

BUTTE, MT

ABSTRACTS with high levels of Cu (up to 8500 ppm), Ge (up to 580 ppm), Ga (up to 5000 ppm), In (up to 2100 ppm), W (up to 2800 ppm), and Ag (up to 100 ppm), present in the ZnS lattice (substitutions) and not as inclusions. It was determined that the fluorescence is associated with a high sulfidation state, where the low-Fe sphalerite is with enargite and tennantite. Fluid inclusion and stable isotope studies indicate vein formation at 200-500 °C and depth of 5-6 km from magmatic fluids.

the Redtail Area. In addition to these, local structural variations also contribute to Shmax rotation and fracture heterogeneity. Mineralogical and geochemical data from fracture fills offer critical insights into the timing and conditions of fracture formation and healing. Understanding fracture patterns can aid in selecting optimal drilling orientations, improving well placement, and enhancing the efficiency of hydraulic fracturing operations. Furthermore, this integrated methodology can be applied to other structurally complex basins to enhance reservoir characterization and management strategies.

Two nearby outcropping quartz-feldspar porphyry intrusions, dated at ~66 million years old by U-Pb on zircon, are thought to relate to the polymetallic veins. Trace elements in the zircon indicate a fertile Mo-Cu system. Although the exact age of the polymetallic veins is unknown, it likely matches that of the quartz-feldspar porphyries. Some geophysical surveys and the vertical zonation of the ore suggest that more porphyry intrusions are concealed beneath the sedimentary rocks. This suggests potential for undiscovered porphyry intrusions that may host Mo-Cu deposits.

Session: All Meeting Posters Room: Exhibit Hall - Copper Lounge POLYMETALLIC POTENTIAL, INCLUDING CRITICAL ELEMENTS, OF THE PHILIPSBURG MINING DISTRICT, GRANITE COUNTY, MONTANA. Presenter: Beaucamp, Celine M. (Montana Technological University) Demand for locally sourced resources has prompted a reevaluation of historic mining districts. The Philipsburg district, known for its rich mining history, significantly contributed to Montana’s mineral production, ranking 2nd in the state. Operating from 1865 until the 1980s, it yielded > 50 M oz of Ag, 113,000 oz of Au, 36 M kg of Zn, 10 M kg of Pb, 1.8 M kg of Cu, and 295,000 tonnes of pure battery-grade MnO2. While W mineralization exists, specific production data is unavailable. Main ore production comes from polymetallic quartz veins and lodes, some parallel to bedding in limestones, and others steeply dipping within more silicate-rich sediments and in the batholith. A zonation pattern in ore distribution is present: Cu and Ag ores are concentrated near quartz-feldspar porphyries, with Zn, Pb, and Au increasing with distance. This pattern mirrors wellstudied Cordilleran polymetallic vein/lode deposits such as the Butte district in Montana or the Morococha district in Peru. Veins in the central area contain sphalerite showing vibrant colors under longwave UV light (365 nm); LA-ICP-MS analyses show that this fluorescent correlates

2026 RMS AAPG

Additionally, the district experienced international recognition in the early 1900s for its Mn-rich replacement deposits, featuring rare battery-grade MnO2. This ore results from the secondary alteration of Mn-carbonate minerals, transitioning to rhodochrosite at depth. It forms tabular bodies and pods in favorable beds, adjacent to nearvertical quartz veins and fissures. Some Mn deposits are also associated with Au and other trace elements, especially in the district center. The district was recently studied in the context of a PhD thesis, but ongoing research, mainly through projects by senior Bachelor students completing their Geological Engineering capstones in partnership with the Contact Mining Co. and the Granite Resource Co., continues to explore its mineral potential. Session: Montana Energy Resources and Geology Room: Room 2 - Kelley/Seward Day/Time: Monday, October 26, 3:30 pm

29

BUTTE, MT

ABSTRACTS recent assessment of the Great Basin based on an enhanced geothermal systems approach shows how the methodology will be applied to sedimentary basins.

MODELING GEOTHERMAL RESOURCE POTENTIAL IN SEDIMENTARY BASINS OF THE ROCKY MOUNTAIN REGION Presenter: Birdwell, Justin E. (U.S. Geological Survey, Central Energy Resources Science Center)

Session: Geothermal Resources Room: Room 2 - Kelley/Seward

Co-authors: Rand D. Gardner and Erick R. Burns (U.S. Geologica Survey)

Day/Time: Sunday, October 25, 8:35 am

Deep hot sedimentary basins have been identified as potential targets for geothermal resource development. To evaluate the geothermal resource potential of basins in the Rocky Mountain region, a basin modeling approach is being used to create three-dimensional (3D) temperature models that incorporate stratigraphic, structural, and lithologic data combined with bottom-hole temperatures (BHTs) collected primarily by the petroleum industry. These models provide estimates of subsurface temperature and conductive heat flow throughout the sedimentary column calibrated to the available measured temperatures and accounting for rock thermal properties. Thermally calibrated 3D basin models can be used for a variety of exploration and assessment applications, such as identifying areas where temperatures are sufficiently high to economically generate electricity (>90°C) or areas that have potential for direct use or thermal energy storage applications. To date, USGS has developed calibrated thermal models for several basins in the Rocky Mountain Region, including the Denver-Julesburg, Piceance, and Williston basins. Useful outputs that can be extracted from 3D basin models include: (1) temperature maps at depths of interest, (2) depth-to-temperature maps for identifying areas with different grades of geothermal resource, and (3) maps of formations and lithologies that might inform which units have development potential. For USGS regional assessments of subsurface geothermal resources, these outputs provide the basis for estimating the total recoverable thermal resource based on geology and thermal properties, coupled with an idealized development approach that requires engineering reservoir permeability to facilitate thermal energy extraction and conversion to electricity. An example from the

2026 RMS AAPG

POTENTIAL FOR THE RECOVERY OF HYDROGEN FROM ORGANIC-RICH GREEN RIVER OIL SHALES IN PICEANCE BASIN, COLORADO Presenter: Birdwell, Justin E. (U.S. Geological Survey, Central Energy Resources Science Center) Hydrogen (H2) has been considered one potential alternative to hydrocarbon fuels, and recent exploration for hydrogen in its gaseous, diatomic form in subsurface reservoirs has greatly expanded. Another possible source of geologic hydrogen in the subsurface can be found in thermally immature, organic matter-rich sedimentary rocks. The Eocene Green River Formation in the Piceance Basin of northwestern Colorado represents one of the largest deposits of hydrogen-rich organic matter in the world, based on a detailed evaluation of the oil shale potential in the basin. Nearly 1,000 wells with core or cuttings have been drilled to assess oil shale potential, yielding more than 300,000 Fischer assay measurements that characterize the stratigraphic and geographic variability of organic matter in these sedimentary rocks. Within the approximately 5,500 square miles of the basin and up to 2,000 ft thick interval of the Green River Formation, an estimated 1.5 trillion barrels of oil equivalent has been estimated to be present. Extensive research into the lacustrine organic matter in the Green River Formation shows that the hydrogen content is very high relative to other organic-rich sedimentary rocks, with hydrogen index values from programmed temperature pyrolysis regularly exceeding 1,000 mg/g and atomic hydrogen to carbon ratios in kerogen isolates averaging around 1.5 and as high as 1.7. Roughly 34.2 billion metric tons of hydrogen are potentially present in Green River Formation oil shales of Piceance Basin based on an estimated

30

BUTTE, MT

ABSTRACTS U.S. Geological Survey (USGS) Energy Resources Program has drilled two research cores into the Mancos Shale over the last 20 years in western Colorado. The USGS Candy Lane 1 core was drilled in Montrose County in 2005, recovering ~540 ft of Upper Cretaceous Mancos Shale up through the lower part of the Niobrara Member or Smoky Hill equivalent. In 2011, the Adobe Buttes 2-11 core was drilled in Delta County to capture a more complete interval of the upper part of the Niobrara Member. Since the collection of these cores, a variety of characterization studies have been conducted to better understand the source rock potential of organic-rich units and to evaluate features of the depositional setting in the central Cretaceous Western Interior Seaway over the time period that these rocks represent. To date, bulk organic geochemistry, elemental geochemistry, and mineralogy data have been collected on samples from both cores. In addition, detailed ammonite biostratigraphy and organic carbon isotopes of the Candy Lane core from previous studies provide stratigraphic age control for correlation to regionally age-equivalent rocks and for comparison to sedimentary rocks at other locations around the world. Programmed temperature pyrolysis parameters and preliminary organic petrography indicate that the organic matter in both cores is thermally immature for hydrocarbon generation. The bulk organic data primarily provide insights into the variable organic matter accumulation and preservation within the different intervals of the Mancos Shale at these locations and show that the Fairport, Juana Lopez, and Niobrara Members all have sufficient organic matter content and quality to be considered good to excellent petroleum source rocks. Elemental proxies and mineralogy indicate fluctuating paleoenvironmental conditions between and within mudstone units in this part of the Seaway. Based on the petrographic analyses, the samples generally contain a mixture of marine and terrigenous organic matter, but the relative influence of terrigenous input and variable preservation conditions in the water column on source rock quality is currently uncertain. Several redox-sensitive elemental proxies indicate the intervals with lower organic richness and

total organic carbon (TOC) content from Fischer assay yields (TOC = ~2×oil yield in bbl/ton) and an average kerogen hydrogen content for Green River oil shales (11.5 wt. %). However, it is unlikely that more than a small fraction of this hydrogen could be recovered from the pyrolysis product stream and separated into H2 gas. Pyrolysis tests conducted by the U.S. Geological Survey and industrial oil shale developers have shown that as time and temperature conditions are adjusted, the amount of hydrogen released as a co-product of pyrolysate generation vary. In tests that simulate in situ retorting technologies, generated gases were found to have hydrogen content of up to 12 mol % (360°C, 6 hours). Using a typical gas-to-oil ratio from Green River oil shale pyrolysis (~0.2 g/g from Fischer assay) and this hydrogen content for the pyrolysis gas, an estimated 1.5% (515 million metric tons) of the total organic hydrogen in Green River oil shale would be potentially recoverable as H2 gas. Furthermore, experiments using oil shales from other formations in China using higher temperatures (up to 450°C) have yielded larger fractions of generated gas with higher H2 content (up to 30 vol.%), indicating that optimized pyrolysis conditions could greatly increase the potential for hydrogen production from oil shale retorting. Session: Helium and Hydrogen Room: Room 2 - Kelley/Seward Day/Time: Monday, October 26, 8:35 am CHEMOSTRATIGRAPHY OF THE UPPER CRETACEOUS MANCOS SHALE, WESTERN COLORADO Presenter: Birdwell, Justin E. (U.S. Geological Survey, Central Energy Resources Science Center) Co-authors: Jason A. Flaum (U.S. Geological Survey) The Upper Cretaceous Mancos Shale is a thick marine mudstone package that contains petroleum source rocks and records geochemical signatures reflective of the depositional setting during a dynamic period in the Cretaceous Western Interior Seaway of North America. The

2026 RMS AAPG

31

BUTTE, MT

ABSTRACTS Cretaceous and Tertiary igneous rocks. Basin fill is Tertiary sedimentary and volcanic rocks of the Renova and Sixmile Creek Formations and unconsolidated Quaternary deposits.

hydrocarbon-generating potential were deposited under more oxic conditions that are less conducive to preserving hydrogen-rich marine organic matter. In contrast, sulfur-to-iron ratios and molybdenum enrichment factors imply periods of anoxia during deposition of the intervals with the best source rock potential. Subtle shifts in detrital sources at the locations these cores were taken from are inferred from major element ratios and distributions of rare earth element elements. Mineralogy and major element data show that the units below the Montezuma Valley Member are dominated by clay minerals and quartz, with the exception of thin limestones in the Juana Lopez, and shallower intervals generally contain more carbonate including dolomite in the Niobrara Member. These results are relevant to USGS petroleum resource assessments and provide insights into how paleoenvironmental conditions evolved during the Late Cretaceous in the Western Interior Seaway.

A focus of new mapping was the tectonostratigraphic framework of the Neogene Sixmile Creek Formation, a heterogenous assemblage of fluvial and alluvial conglomerates, tuffs, reworked tuffaceous sediments, and volcanic flows deposited during development of the Yellowstone hotspot system and comprising much of the basin fill in southwestern Montana. Previous workers divided the formation into three members: the basal Sweetwater member consisting of angular basement clast fanglomerate deposits; the middle Anderson Ranch member of ash beds interlayered with siltstone, sandstone, and well-rounded pebble conglomerate channels; and the upper Big Hole River member consisting of fluvial round stone conglomerate, siltstone, and sandstone.

Session: Chemical Geology

MBMG mapping demonstrates that the Sixmile Creek members overlap in space and time, and that these members are better described as coeval facies defined by basin position (e.g., marginal or axial) rather than chronologic members defined by stratigraphic position. Zircon U-Pb geochronology of tuffaceous beds within the interfingering facies records influxes of Yellowstone hotspot-derived sediments at ca. 16.5, 12.5, and 10–8 Ma, corresponding to the McDermitt through Picabo volcanic fields. Along the basin margin, the ca. 16–7.5 Ma stratigraphic succession is capped by the ca. 6 Ma Timber Hill basalt flow likely sourced from the Heise volcanic field. Closer to the modern axial drainage of the basin, the ca. 2 Ma Robb Creek tuff overlies ca. 10 Ma Sixmile Creek strata.

Room: Room 1 – Big Butte/Highlands Day/Time: Sunday, October 25, 4:00 pm GEOLOGIC MAP OF THE METZEL RANCH AND RUBY DAM 7.5’ QUADRANGLES, SOUTHWESTERN MONTANA Presenter: Brennan, Daniel T. (Montana Bureau of Mines and Geology) The Metzel Ranch and Ruby Dam 7.5′ quadrangles are 30 km (19 mi) east of Dillon and 100 km (60 mi) northeast of Yellowstone National Park. They were mapped and compiled during the 2022–2024 field seasons at 1:24,000 scale for addition to the Dillon 30’ x 60’, 100:000 scale map to be published under the Montana Bureau of Mines and Geology (MBMG) STATEMAP program.

Consequently, the upper Ruby basin is interpreted to record continuous sedimentation from ca. 16.5–6 Ma, coincident with the McDermitt through Picabo volcanic fields. Following the onset of the Heise Volcanic field at ca. 6 Ma, the basin predominately records exhumation and incision. More broadly, interpreting the Sixmile Creek “members” as facies emphasizes that the regional

The map area encompasses the upper Ruby basin and flanking Greenhorn and Ruby ranges. Bedrock consists mainly of deformed Archean to Paleoproterozoic metamorphic basement rocks of the Elk Gulch Suite, Dillon Gneiss, and Christensen Ranch Suite; Paleozoic to Mesozoic sedimentary rocks; and volumetrically minor

2026 RMS AAPG

32

BUTTE, MT

ABSTRACTS GOR’s. Outboard of this fairway, a more proximal play dominated by clastic sediments, mostly normally pressured and charged by migrated hydrocarbons. This play has an average maturity of 0.5-0.7 VRo and produces highly viscous black wax with very low GOR’s. To date, these wells have not been successful, but the test data and reservoir mapping suggest significant opportunities.

lateral and stratigraphic continuity characteristic of passive margin and some foreland basin successions should not necessarily be assumed for intermontane basin systems. Session: All Meeting Posters Room: Exhibit Hall - Copper Lounge PUSHING THE UTELAND BUTTE PLAY TO ITS ECONOMIC EDGES, THE GREEN RIVER FORMATION, UINTA BASIN, UTAH

Session: Uinta Basin 1: Green River Formation

Presenter: Brinkerhoff, Riley (HIVE Partners)

Room: Room 1 - Big Butte/Highlands

Over 565 horizontal wells have been drilled in the large and growing Uteland Butte play in the past 15 years, with decidedly variable results. The best wells cum north of 300K barrels in the first 12 months on production, with conservative EUR’s well above a million barrels per well. Conversely, the poorest Uteland Butte wells IP less than 10K in the first year and will never pay out their drilling costs. The core of the Uteland Butte play has been well understood for years, but how far the play may extend is still being explored. As inventories of Uteland Butte wells are drilled up, developing economic opportunities in the play further away from the basin center has become more important. Pore pressure, reservoir temperature, well length and frac size are recognized as important controls on well productivity, but the variable reservoir types within the shallower Uteland Butte play area are perhaps less understood. To the south and east of the current play fairway, an intercrystalline-pore dominated fairway has been mapped, with dolomites acting as the best reservoirs and at normal pressure or slightly above with mostly migrated hydrocarbons. This portion of the Uteland Butte fairway was the first to be drilled horizontally because the dolomite reservoirs appeared to be the most conventional targets, but the original wells were disappointing. Operators have returned to test this fairway with modern fracs, with encouraging results. The Uteland Butte is quite thick in this fairway, consisting of over 130’ carbonates and black shales, but only a fraction of that are highporosity dolomites. This play has an average VRo of 0.6 to 0.8 and produces a black wax with low

Day/Time: Sunday, October 25, 1:45 pm

2026 RMS AAPG

A DEFORMATION MECHANISM FOR THE DUCHESNE FAULT ZONE AND ITS IMPACTS ON THE UINTA BASIN HORIZONTAL OIL PLAY Presenter: Brinkerhoff, Riley (HIVE Partners) The Uinta Basin of northeastern Utah is a Laramide-aged foreland basin, created by lithospheric loading by the rising Uinta Mountains. For approximately ten million years during the Eocene, this subsiding basin was filled by Lake Uinta, resulting in over 7,000 meters of lacustrine deposits in the center of the Basin. The resulting Green River Formation famously consists of highkerogen oil shales, interbedded with lacustrine carbonates, mudstones and sandstones. Contemporaneous with this lacustrine deposition, Laramide compression of the developing Uinta Basin resulted in many basement rooted faults, one of which is the Duchesne Fault Zone. Few of these basement faults cut far into the overlying sediments, instead resulting in broad folds and anticlines at the surface. Related faulting, namely the Duchesne Graben and associated fault zone, all contained within the lacustrine sediments of the Green River Formation is the focus of this presentation. Lacustrine oil shales, with organic contents up to 30% by volume, are structurally ductile and when placed under stress, readily shear and deform significantly before adjacent strata do. As such, these oil shales form décollement surfaces within fault zones. Within the deeply rooted Laramide folds, extension occurs above the fold’s neutral

33

BUTTE, MT

ABSTRACTS investigations of all controlling properties and processes resulting in the formation of conventional and unconventional oil and gas accumulations. Methods include quantitative, multi-dimensional reconstructions of sedimentary basin and fluid system evolution over geologic timescales, including burial histories, rock properties, tectonics, thermal histories, pressure, fluid generation, fluid migration, and the trapping, accumulation, and preservation of fluids and associated resources. Spatial scales range from basin to play to prospects, and timescales range from over a billion years to less than a hundred years.

surface as sediments thin and fault on the highly ductile oil shales. Grabens are a common feature of this extension, with the bounding faults having throws of just a few meters in smaller examples, to well over 200 meters in the Duchesne fault zone, the largest such feature in the basin. Below the neutral surfaces, small compressional folds and thrusts are also observed. These are also contained in the lacustrine sediments, but do not appear to be as tightly bound to the ductile oil shales. This presentation will show mapping of the Duchesne fault zone across the center of the Uinta Basin, the depth of individual faults and how they are consistently rooted in ductile oil shales. A deformation model is then presented, showing that the fault zone and associated grabens are contained within larger folds, and that deep, basement faulting is the underlying structure that controls fold development. Subsurface data also show these faults and grabens are correlated with rich oil shales that provide ductile slip surfaces. The beds containing the actual decollement surfaces are typically quite narrow, usually less than a half meter in width, but are the richest TOC beds within the adjacent strata.

These proven concepts are now being increasingly invested to improve efficiencies in exploration for subsurface energy resources, such as geothermal and hydrogen, and for mineral systems. The key benefits are very similar to those achieved in petroleum exploration and include: significantly improved understanding of the geological properties and processes that control resource formation; more rigorous data collection, quality controls, and mapping; and the ability to perform process modeling (including reactive transport modeling, though requiring new physics implementations to handle aqueous transport) on all timescales that impact resource development. A final benefit is the ability of the modeling process to improve communications both within multidisciplinary teams and between technical and management teams.

Session: Uinta Basin 2: Green River and Paradox Resources Room: Room 1 - Big Butte/Highlands Day/Time: Monday, October 26, 1:15 pm SUBSURFACE SYSTEMS MODELING: FROM PETROLEUM TO NEW ENERGY AND MINERAL SYSTEMS

However, despite clear parallels between numerous of the fundamental processes controlling petroleum system evolution and sedimentary basin-hosted mineral system evolution, the adaptation and application of powerful BPSM capabilities to the exploration and study of ore deposits is but nascent. Here, we present frameworks for modeling basin-hosted mineral systems. Alongside geologic hydrogen, CCS, and mineral system case studies, BPSMstyle workflows are discussed as well-suited to sediment-hosted copper (e.g., Central African Copperbelt; Europe’s Kupferschiefer), sedimentary-basin/oilfield lithium brine (e.g., Alberta Basin; USA’s Smackover Formation),

Presenter: Burton, Zachary F.M. (Montana State University) Co-authors: Bjorn Wygrala (Geological Advisor), Daniel Palmowski and Thomas Hantschel (Terranta GmbH) For over half a century, basin and petroleum system modeling (BPSM) has evolved to become an essential component of exploration workflows in global oil and gas companies. Its role in exploration is comparable to the role of reservoir modeling in production. BPSM enables

2026 RMS AAPG

34

BUTTE, MT

ABSTRACTS The USGS methodology for assessing natural gas storage capacity relies on well and reservoir data, including spud dates, perforation locations, hydrocarbon production, petrophysical properties, and pressure trends. Development and engineering considerations like permeability and pipeline infrastructure are not yet considered. Instead, assessment results are probabilistic with aggregation to play, petroleum province, regional, and national scales. The methodology was demonstrated on seven anonymized abandoned natural gas reservoirs in two separate plays (Mississippian Sandstone Gas and the Clinton Structural Plays) in the Michigan Basin Province. In addition, the methodology was tested relative to the reported working gas storage capacity of 31 existing natural gas storage reservoirs in Michigan. The methodology was able to produce r2 values of between 0.84 and 0.90 when predicting the storage capacity of the known natural gas storage reservoirs. This methodology is currently being used to systematically and consistently assess hydrocarbon plays and provinces for natural gas storage capacity across the United States.

geothermal-basin lithium brine (e.g., Upper Rhine Graben; California’s Salton Sea), Mississippi Valley-type lead-zinc (e.g., Missouri’s Viburnum Trend; Canada’s Pine Point; the Irish orefield), and basin-hosted uranium systems, with additional applicability to sedimentary-exhalative zinc-leadsilver (e.g., Australia’s McArthur River, Mount Isa; Alaska’s Red Dog), closed-basin lithium brine (e.g., South America’s Lithium Triangle; Nevada’s Clayton Valley), and, potentially emerging basinor brine-hosted rare earth element systems. Session: Subsurface Utilization Room: Room 2 - Kelley/Seward Day/Time: Monday, October 6, 10:35 am INTRODUCING A QUANTITATIVE AND PROBABILISTIC METHODOLOGY FOR EVALUATING NATURAL GAS STORAGE CAPACITY IN DEPLETED HYDROCARBON RESERVOIRS Presenter: Buursink, Marc (U.S. Geological Survey) Co-authors: Ashton M. Wiens, Matthew M. Jones, Brian A. Varela, Sean T. Brennan, Matthew D. Merrill, Peter D. Warwick (U.S. Geological Survey)

Session: Subsurface Utilization Room: Room 2 - Kelley/Seward

Growth in energy storage capacity could help meet the increasing demand for reliable power to both meet the demands of peak energy consumption and complement the over and under production of intermittent renewable electricity sources. Geologic energy storage (GES) already exists underground, primarily in the form of natural gas storage reservoirs, with capacity and duration that may far exceed battery storage technologies. Broader development of GES would enable storing gases such as methane and hydrogen to meet potential increases in energy demand. The U.S. Geological Survey (USGS) has developed a methodology for assessing natural gas storage capacities in depleted natural gas reservoirs on a national scale. The methodology uses three quantitative approaches for calculating gas storage capacity, including recorded production, reservoir volumetric parameters, and material balance.

2026 RMS AAPG

Day/Time: Monday, October 25, 11:00 am BEARPAW GRAVITY FAULTING AND BIOGENIC GAS EXPLORATION ST JOE ROAD FIELD; A NIOBRARA FAULT GOUGE TRAP HILL COUNTY, MONTANA Presenter: Caldwell, Mark S. (Northshore Energy LLC) Eocene uplift of the Laramide Bearpaw Arch gave rise to a gravity-driven fault system above horizontal shale detachments in Upper Cretaceous marine sedimentary rocks. Gravity driven deformation consists of an upslope extensional domain (normal faults and grabens) that is compensated by a down-slope compressional domain (fold and thrust belt, tear faults). Gravity slides off the Bearpaw uplift cover thousands of sq. mi and created a near circular fault pattern as mapped on the surface south of the Bearpaw Mountains. (Reeves, 1946). Seismic

35

BUTTE, MT

ABSTRACTS St. Joe Road Field (2001) is a combination structural-stratigraphic trap that covers 40 sq mi and has produced over 25 Bcfg from 111 wells in the Niobrara Sandstone. The updip trapping seal for St. Joe Road Field is formed by fault gouge seal developed along the right lateral St. Joe Fault (SJF), The Niobrara Sand pinches out to a zero edge forming the north and south trap geometry.

exploration for shallow (800 to 2600 Ft.) biogenic gas reservoirs north of the Bearpaw Uplift reveals a similar radial pattern of thrust faulting that is hidden at the surface beneath a glacial veneer. Gravity Faulting The study area is located north of the Milk River within the region of compressional deformation. Two distinct episodes of gravity faulting are apparent; First, a 10 to 15-mile-wide belt of “popup” structures or “toe thrusts” formed above the First White Specks (1WS) decollement, located in overpressured organic rich shale. Second, these pop-up structures were then carried piggyback by faulting associated with the lower, younger Second White Specks (2WS) decollement. The gravity slide plain stepped down 300 Ft. and spread to a much broader area than the earlier 1WS slide block. Large E-W trending thrust faults with over 1200 ft. of throw linked to long throughgoing right lateral tear faults characterize this deformation. The tear faults show 5,000 to 15,000 feet right-lateral displacement as measured by piercing points at mapped fault intersections.

Evidence for a fault gouge seal includes:

St Joe Road Field Historically, the primary exploration objective around the Bearpaw Uplift has been the Upper Cretaceous (Campanian) Eagle Sandstone. Highquality marine shoreface reservoirs of the Eagle Sandstone have produced over 400 Bcfg from a wide variety of structural traps, all fundamentally related to gravity-induced movement down the flanks of the Bearpaw uplift.

SJF, Tear fault over 30 miles long

•

Right lateral displacement on piercing points of 3500-15,000 Ft.

•

SJF shows variation in sense of throw along strike.

•

Both down to the east and up to the east are observed on 3D seismic.

•

Niobrara Pay is found only on east side of the SJF. Updip, across the fault, is wet

•

Seismic bright spot DHI shows increased amplitude in the Niobrara reflector

•

Fault zone cataclasis and fault gouge formation is expected (but not observed)

Session: Montana Energy Resources and Geology Room: Room 2 - Kelley/Seward Day/Time: Monday, October 26, 3:55 pm ORGANIC CARBON DISTRIBUTION IN SUBMARINE DEPOSITIONAL SYSTEMS OF THE LEWIS SHALE, GREATER GREEN RIVER BASIN, WYOMING

More recent exploration (2000’s) led to the discovery of St. Joe Road Field in the underlying Upper Cretaceous Niobrara Sandstone (Santonian). The sand was deposited as a single coarsening upward sequence and is described as very-fine grained, shaly sand and silt, interlaminated with dark shale and bioturbated mudstone. This sequence is capped with a northeast trending distal middle to lower shoreface sand body with thickness from 0-25 Ft. Core porosities are as high as 28% and permeability’s as high as 250 MD.

2026 RMS AAPG

•

Presenter: Charoensuk, Jutamas (Colorado School of Mines) Co-authors: Mark Nell (Wexpro Company) and Zane Jobe (Colorado School of Mines) Understanding the distribution and preservation of organic matter in submarine depositional systems is critical for quantifying the global carbon cycle and predicting the distribution of conventional source rocks and unconventional reservoirs. Turbidity currents efficiently transport organic matter into deep-water environments, and organic-matter distribution and preservation are

36

BUTTE, MT

ABSTRACTS clay-rich deposits to coarser-grained siliciclastic sediments and increasing detrital sediment input. These trends are consistent with progressive southward progradation of the depositional system.

influenced by sediment routing, depositional processes, and external boundary conditions. The Upper Cretaceous Lewis Shale of the Green River Basin, provides an excellent record for investigating these relationships across mud-rich shelf, slope, and toe-of-slope environments. Although the Lewis Shale has produced significant hydrocarbons, the controls on sediment dispersal and organic-carbon distribution remain poorly understood.

Overall, the Lewis Shale records significant changes in sediment routing, provenance, depositional energy, and organic-matter preservation. The integration of geochemical and sedimentological data provides a framework for understanding the controls on organic-carbon distribution and evaluating the stratigraphic evolution and petroleum-resource potential of the Lewis Shale.

This study integrates subsurface and outcrop datasets to evaluate stratigraphic and spatial variations in sediment dispersal and organic matter distribution within the Lewis Shale. Core and cuttings pyrolysis data from 105 wells were analyzed for total organic carbon (TOC), hydrogen index, and oxygen index within flooding-surfacebounded stratigraphic units. In addition, 72 outcrop samples from five locations were analyzed using LECO TOC and portable X-ray fluorescence techniques. Elemental ratios, including Si/Al, Zr/Al, and Ti/Al, were used to evaluate changes in grain size and detrital siliciclastic input.

Session: All Meeting Posters Room: Exhibit Hall - Copper Lounge GEOTHERMAL RESOURCE ASSESSMENT OF MONTANA FOR ENHANCED GEOTHERMAL SYSTEMS (EGS) POWER PRODUCTION Presenter: Davison, Ryan C. (Montana Bureau of Mines and Geology) Co-authors: John Sanford (Montana Bureau of Mines and Geology)

Spatial TOC distribution maps indicate predominantly north-to-south sediment transport through the Lower Lewis, followed by a northeastward shift in dispersal during the middle interval, consistent with sediment-routing avulsion. Upper units record evidence for an additional southern sediment source. Organic carbon is preferentially concentrated in mudstone facies, whereas siltstone and sandstone generally contain low TOC (<0.3 wt.%).

Montana holds significant underutilized potential for high-temperature geothermal power, yet existing research is largely limited to shallow depths. This study presents a comprehensive, statewide resource assessment targeting deep, tight-rock reservoirs—specifically the Precambrian basement—for Enhanced Geothermal Systems (EGS) development. We integrated subsurface data from approximately 12,000 wells, 2D seismic reflection profiles, regional gravity and magnetic surveys, and geothermometry to map basement topography and isolate thermal anomalies. This workflow identified over a dozen high-priority areas. To date, four sites representing diverse geologic provinces have undergone detailed assessment: the Deer Lodge Basin, Big Timber, Colstrip, and Poplar Dome. This selection spans extensional basins in western Montana to structural highs on the western flank of the Williston Basin in eastern Montana. All four focus areas exhibit commercial-

TOC generally decreases stratigraphically upward and from north to south, although elevated TOC in the western Upper Lewis supports increased organic-matter input associated with the inferred southern sediment source. High TOC, high HI, and low OI values identify intervals of enhanced preservation of hydrogen-rich organic matter under reducing conditions, likely related to focused organic-matter delivery, rapid burial, and limited oxidation. Si/Al, Zr/Al, and Ti/Al ratios generally increase upward and from north to south, indicating a transition from finer-grained,

2026 RMS AAPG

37

BUTTE, MT

ABSTRACTS newly completed Uteland Butte wells and one Castle Peak well between November 25, 2024, and February 3, 2026. This sampling captures the complete transition from initial frac fluid flowback to stable formation water production. A central component of our approach is the quantitative comparison of these time-series samples with geochemical end-member prototypes. These prototypes encompass meteoric and supply waters, as well as distinct formation waters from the surrounding stratigraphy, including the overlying Douglas Creek, Carbonate Marker, and Castle Peak members, and the underlying Wasatch Formation. As injected frac fluids are extracted, the relative amount of connate water (in the produced fluids and in the subsurface) increases driving water chemistry towards these stable prototype compositions. By utilizing these distinct isotopic and elemental fingerprints, we can accurately pinpoint the specific stratigraphic sources contributing to variable water cuts in the Uteland Butte Member. Ultimately, these findings establish a robust subsurface connectivity framework that can be applied to existing reservoir models to improve the predictability of hydrocarbon-to-water ratios throughout the Uinta Basin.

grade thermal resources, with subsurface measurements confirming temperatures exceeding 300°F (149°C) as shallow as 7,100 ft (2,164 m). Furthermore, extrapolation indicates temperatures reaching 400°F (204°C) as shallow as 9,850 ft (3,002 m). These conditions satisfy the requirements for modern binary-cycle and flashsteam power generation. Ongoing work in the data-dense Deer Lodge Basin is establishing a standardized exploration template for western Montana. Once finalized, this predictive template will be deployed to evaluate the remaining 34 major Tertiary basins, prioritizing areas with active surface hydrothermal expressions. Session: Geothermal Resources Room: Room 2 - Kelley/Seward Day/Time: Sunday, October 25, 9:00 am MAXIMIZING UINTA BASIN (UTAH, USA) OIL YIELD THROUGH GEOCHEMICAL FINGERPRINTING OF PRODUCED WATER Presenter: Day, Troy (Brigham Young University) Co-authors: John H. McBride, Kevin A. Rey, Landon K. Burgener, and Samual M. Hudson (Brigham Young University); Stephen P. Phillips and Christopher Perfili (Wasatch Energy Management): Alonzo, R. Brinkerhoff (Duchesne River Resources)

Session: Uinta Basin 1: Green River Formation Room: Room 1 - Big Butte/Highlands

Since 2017, the Uinta Basin has seen a significant rise in hydrocarbon extraction, driven by modern drilling and hydraulic fracturing techniques, including higher frac loadings. The primary target of these operations is the Uteland Butte Member of the Green River Formation, an interval characterized by interbedded limestone, dolostone, and organic-rich mudstone. However, oil production has been accompanied by a problematic surge in co-produced water, an undesirable by-product. Wells exhibit highly variable water-to-oil recovery ratios following large fracturing operations, which have substantially increased disposal costs. To address this issue, this study employs isotopic (δ¹⁸O, δD) and elemental geochemistry to track the temporal evolution of produced water. We conducted comprehensive time-series sampling from seven

2026 RMS AAPG

Day/Time: Sunday, October 25, 2:10 pm COPPER CLIFF GOLD-RICH PORPHYRY COPPER OCCURRENCE Presenter: Ellsworth, Peter C. (Mogotes Metals Inc.) The Copper Cliff district lies in the western Garnet Range ~48 km east-southeast of Missoula, Montana, and produced ~111,000 lb Cu, 259 oz Au, and 567 oz Ag from carbonate replacements and hyrdrothermal siliceous breccias between the 1890s and 1940s. Proterozoic Garnet Range Formation quartzite of the Belt Supergroup metasediments and overlying Cambrian Silver Hill and Hasmark Formation carbonates form a southeast-plunging anticline within complex structural deformation enveloped within the Lewis

38

BUTTE, MT

ABSTRACTS and Maher, 2018). Copper Cliff preserves an unusually complete lithocap-to-porphyry transition, a gold-rich (Au:Cu ≈ 1) endmember among Montana’s Eocene porphyry occurrences, and an exploration model for exploring beneath advanced argillic lithocaps in the northern Rockies.

and Clark line. Early Eocene extension opened conduits for quartz latite plutons, dikes, and plugs along ENE-, NE-, and NW-trending belts. Advanced argillic alteration — quartz, alunite, kaolinite, dickite, pyrophyllite, diaspore — dominates the district center within a bleached, pyritized envelope >4 km long and ~1 km wide, flanked by intermediate argillic, phyllic, and propylitic alteration assemblages. Tabular hydrothermal breccias cut sediments and intrusive rock and host enriched Cu-Au as sulfosalts (enargite, luzonite, famatinite) and sulfides. Alteration zonation, hypogene alunite and enargite, magmatic sulfur isotope values, and a gold-bearing late sericite overprint led Ellsworth (1993) to interpret the district as an enargitebearing quartz-alunite epithermal system underlain by a gold-rich porphyry copper system.

Session: All Meeting Posters (with core) Room: Exhibit Hall - Copper Lounge MACHINE LEARNING-BASED GOLD PROSPECTIVITY MAPPING IN THE YILGARN CRATON, WESTERN AUSTRALIA Presenter: Fields, Kayla J. (Radford University) Co-authors: Naveen Joseph, Stockton Maxwell, and Andrew Foy (Radford University) Intensive mining exploration practices can place significant stress on the environment, disrupt critical habitats, and are costly, particularly in environmentally sensitive areas. The increasing application of machine learning in mineral exploration can improve the efficiency and costeffectiveness of identifying prospective areas. This study aims to identify gold prospectivity zones in the Yilgarn Craton, Western Australia, using machine learning methods to evaluate their effectiveness for mineral exploration and assess the geological features associated with gold occurrence in this region. Generalized Linear Regression (GLR) and Maximum Entropy (MaxEnt) models were developed using gold presence points and nine predictor variables. Gold presence points were randomly divided into 80% for model training and cross-validation and 20% for independent evaluation of the model performance. Both models demonstrated strong predictive performance, with 87.4% of testing points falling within the top 20% of gold prospectivity predicted by GLR and 85.0% falling within the top 20% predicted by MaxEnt. Partial response plots from the MaxEnt model were used to examine the relationships between predicted gold prospectivity and the predictor variables. The results indicated that geochronology samples, linear structures, dykes, and pathfinder elements were important predictors of gold prospectivity.

Twenty-five core holes totaling ~32,000 m, drilled to maximum depth of 2,020 m in 2006–2017, confirmed that interpretation. A near-vertical AuCu porphyry underlies the lithocap, where >0.3% CuEq mineralization lies 470–620 m below surface and extends over ~1,000 vertical meters. Copper occurs as fine-grained disseminated and vein-controlled chalcopyrite ± bornite with specular hematite ± anhydrite in potassic and early green phyllic alteration of multiphase porphyry; a later, structurally controlled white mica-quartz-pyrite assemblage overprints alteration minerals. Holes returned continuous intervals >1,000 m at 0.3–0.5 g/t Au and 0.3–0.5% Cu, with Au:Cu ratio typically ≥1:1 and locally 2:1. Cu:Au ratio increases with depth; the gold-poor cap reflects shallow deposition at or below 200 °C by magmatic-meteoric fluid mixing (Fairbanks, 2009). U-Pb zircon ages of 48.7–47.1 Ma for the intrusive complex, a Re-Os molybdenite age of 49.6 ± 0.2 Ma, and alunite ⁴⁰Ar/³⁹Ar and K-Ar ages of 49.8 ± 0.3 and 48.4 ± 1.3 Ma indicate multi-phase intrusions, porphyry mineralization, and advanced argillic alteration were emplaced in the middle Eocene. White-mica Cu/Zn ratios and Al-OH absorption wavelengths in phyllic alteration vector toward the hydrothermal center (Uribe-Mogollon

2026 RMS AAPG

39

BUTTE, MT

ABSTRACTS Member is characterized by distinct bioclastic beds in the proximal sections and calcareous mudstones with rare fossils in more basinal sections. Variations in pXRF elemental ratios further record changes in salinity, redox, and hydrodynamic energy across the basin through time, highlighting spatially and temporally variable lake conditions within this sensitive closed-basin system. Specifically, increases in zirconium concentrations track fluctuating clastic input during Castle Peak deposition, while increases in strontium relative to calcium are interpreted as elevated salinity between sediment pulses.

Both models identified graphitic lithology as a strong predictor of gold prospectivity, while also indicating higher prospectivity associated with calcareous or alluvial soils, limited or no vegetation, and areas farther from Cenozoic landforms. Overall, GLR and MaxEnt demonstrated high predictive performance and strong agreement in identifying prospective zones, and their results were consistent with known geological controls on gold mineralization. Session: Critical Minerals Room: Room 2 - Kelley/Seward Day/Time: Sunday, October 25, 10:35 am

Together, these sedimentary and geochemical proxies show a fundamental shift in Lake Uinta’s basin dynamics, where a siliciclastic-dominated Castle Peak deposition gave way to a clasticstarved, evaporative lake dominated by carbonate precipitation during deposition of the Long Point Member. Importantly, our results indicate that this transition was not synchronous across the basin. Discontinuous bed geometries, lateral thickness variations, and diachronous unit boundaries suggest that topographic barriers, localized delta lobe switching, and proximity to active clastic entry points may have played a critical role in the timing and nature of the transition from siliciclastic to carbonate deposition.

GEOCHEMISTRY AND SEDIMENTOLOGY OF THE UPPER CASTLE PEAK AND LONG POINT MEMBERS OF THE GREEN RIVER FORMATION, UINTA BASIN, UT Presenter: Fullwood, Amelia (University of Montana) Co-authors: Michael Hofmann (University of Montana) and Ryan Gall (Utah Geological Survey) The Upper Castle Peak and Long Point Members of the Green River Formation record an important period of climatic and tectonic change in the Uinta Basin during the Eocene. These units also host significant hydrocarbon reservoirs, particularly in deeper parts of the basin. In this study, we present detailed geochemical data from pXRF analysis and sedimentologic observations from three rock cores and three outcrop sections. The outcrop sections are approximately aligned from east to west along the southern Uinta Basin margin, whereas the cores form an approximate north to south transect that ties the outcrop sections to the basin center.

The lithologic and chemostratigraphic framework developed in this study provides a basis for understanding basin dynamics during this critical interval of the Eocene and for assessing its implications for hydrocarbon exploration. Recognizing the time-transgressive nature of this system aids in predicting lateral reservoir heterogeneity and provides a baseline for future studies evaluating how spatial facies variations control diagenetic pathways, porosity preservation, and overall reservoir quality across lacustrine basins.

Our results reveal significant compositional variability across the basin, driven by a diachronous sedimentary and geochemical response to shifting clastic input within ancient Lake Uinta. Lithofacies logs of the Castle Peak Member document fluvial and deltaic deposition in outcrops along the southern basin margin and gravity-flow dominated deepwater deposition in the cores from the basin center. The Long Point

2026 RMS AAPG

Session: All Meeting Posters Room: Exhibit Hall - Copper Lounge

40

BUTTE, MT

ABSTRACTS Mesaverde Group, Dakota Sandstone, Weber Sandstone, and additional stratigraphic units in the Paradox Formation. The integrated data indicates minimal critical mineral resource potential across most of Utah’s produced waters, with the notable exception of lithium in the Cane Creek shale. Although current standalone economic viability of critical mineral extraction from produced water is limited across most target intervals, compiling these detailed geochemical datasets establishes a framework for understanding subsurface fluid evolution, informing waste management strategies, and evaluating the long-term co-production potential of Utah's petroleum systems.

ELEMENTAL GEOCHEMISTRY OF PRODUCED WATERS FROM OIL AND GAS WELLS, UINTA AND PARADOX BASINS, UTAH Presenter: Gall, Ryan D. (Utah Geological Survey) Co-authors: Lauren P. Birgenheier and Diego Fernandez (University of Utah), Aaron M. Jubb and Andrew L. Masterson (U.S. Geological Survey), Michale D. Vanden Berg (Utah Geological Survey) This study quantified critical mineral concentrations in produced waters from two expanding oil and gas plays in Utah: the WasatchGreen River play in the Uinta Basin (10 horizontal well samples) and the Cane Creek shale play in the northern Paradox Basin (7 vertical and horizontal well samples). We analyzed each sample using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES) to evaluate trace metal concentrations and fluid salinities.

Session: Critical Minerals Room: Room 2 - Kelley/Seward Day/Time: Sunday, October 25, 11:00 am HOW DO METEOROLOGICAL CONDITIONS IMPACT LEAKING ORPHAN WELLS IN MONTANA?

In the Uinta Basin, produced waters exhibit moderate salinities (e.g., 2030-7090 mg/L Na; 2060 mg/L Ca) and sub-economic trace metal concentrations. However, high-resolution sampling across eight Wasatch and Green River horizontal targets from a single multi-well pad reveals that geochemical signatures are strongly controlled by stratigraphy. Elemental trends (e.g., Ca, K, Na, Li) correlate closely with the interpreted paleosalinity of the original lacustrine depositional environments, demonstrating that depositional history is a primary predictor of produced water composition.

Presenter: Gianoutsos, Nicholas J. (U.S. Geological Survey, Central Energy Resources Science Center) Co-authors: Karl B. Haase, Justin E. Birdwell (U.S. Geological Survey), Michael H. Hofmann (University of Montana), Curtis E. Shuck (Well Done Foundation) Over 4,000 hours of continuous emission measurements from 15 high emitting open-hole orphan wells on the Kevin-Sunburst dome in Toole County, Montana were analyzed by the U.S. Geological Survey and the Well Done Foundation. The wells were drilled in the 1920s and 1930s in the same producing formation and share similar drilling and production histories. Some wells are physically located in close proximity to each other but have significantly different mean emission rates. The producing formation for the wells is the Mississippian Madison Group consisting of the Ellis Group and Madison Group combined carrier zone, which primarily produced oil in the northern part of the dome where the wells are located. Time-weighted mean methane emission rates

In contrast, Paradox Basin produced waters exhibit broadly higher trace metal concentrations, notably lithium (up to 56.9 mg/L). While below current standalone economic thresholds, these concentrations highlight a potential secondary resource, particularly if regional petroleum production scales up alongside advancements in wastewater processing infrastructure. These new datasets are integrated with published produced water geochemical data from 24 additional petroleum wells across the Uinta and Paradox Basins, including samples from the

2026 RMS AAPG

41

BUTTE, MT

ABSTRACTS multiscale approach combining optical petrography, micro Xray fluorescence (µXRF) elemental and mineral mapping, and inductively coupled plasma mass spectrometry (ICP MS).

ranged from non-detectable levels up to 2.7 kg/h in their as-discovered conditions, with leaking wells averaging 211 g/h. Measurement intervals ranged from 12 hours to 2 weeks for each well and revealed leak rates can fluctuate by an order of magnitude within hours. Emission rates were influenced by surface winds and diurnal temperature swings, based on continuous monitoring data where some wells showed correlating spikes in emissions and others demonstrated independent flow. Additionally, fluctuations in emission rates often synchronized between wells with overlapping measurement intervals, suggesting weather conditions, such as temperature and wind, affect emission rates up to a factor of 4 with the most relevant being the effect of wind on wells with open holes. These findings indicate that weather-driven processes can significantly influence orphan well leak rates but remain an understudied source of variability in orphan well emissions.

ICP MS analyses reveal substantial variations in REY concentrations both within and between the two formations. Phosphoria samples contain 422.68-697.32 ppm total REEs (ΣREE: La-Lu), with yttrium and scandium concentrations; both samples reached 737.28-1228.62 ppm. µXRF mapping shows a heterogeneous REY distribution and compositionally distinct phosphate-rich domains. Integrated petrography and µXRF mapping reveal heterogeneous phosphatic fabrics ranging from grain-rich domains to fine-grained phosphatic matrices. REY hosting is spatially associated with apatite-group phases interpreted as fluorapatite or carbonate-rich fluorapatite (francolite), indicating that these phases are the principal REY hosts. The analyzed Mowry Shale samples have lower and more variable bulk REY concentrations than the Phosphoria samples, an outcrop sample with ΣREY of 93 ppm with scandium and around 280 ppm ΣREY for the reservoir sample. µXRF maps reveal substantial microscale heterogeneity in critical-element distribution such as Zr and Ti rich domains. Integrated optical petrography and µXRF mineral segmentation show that the quartz rich shale contains abundant detrital grains disposed within a fine-grained matrix, suggesting multiple mineralogical controls on the distribution of the critical elements.

Session: Orphan Well and Well Repurposing Room: Room 2 - Kelley/Seward Day/Time: Monday, October 26, 1:15 pm RARE EARTH ELEMENT AND YTTRIUM ENRICHMENT AND MINERALOGICAL CONTROLS IN THE PHOSPHORIA FORMATION AND MOWRY SHALE, WYOMING Presenter: Gourari, Djihane (Richard and Marilyn Lynch Multidisciplinary Advanced Stimulation Laboratory, Department of Energy and Petroleum Engineering, University of Wyoming)

The results demonstrate contrasting mineralogical controls on critical elements in the two sedimentary rocks. REY concentrations in the Phosphoria Formation are substantially higher and are strongly associated with phosphate-rich domains, whereas concentrations in the Mowry Shale are lower and more broadly distributed among accessory minerals and matrix components. These findings show integrating bulk ICP-MS measurements with µXRF mapping and petrography can identify REY host phases and improve the evaluation of sedimentary criticalmineral systems.

Co-authors: Saraji Soheil (Department of Energy and Petroleum Engineering, University of Wyoming) Sedimentary formations are increasingly being evaluated as unconventional sources of rare earth elements and yttrium (REY), yet the mineralogical controls on REY enrichment in many Rocky Mountain basins remain poorly constrained. This study investigates the distribution, enrichment and mineralogical controls of REY and critical elements in the Mowry Shale and Phosphoria Formation of Wyoming using an integrated

2026 RMS AAPG

42

BUTTE, MT

ABSTRACTS Session: Rocky Mountain Petroliferous Basins: Mowry Shale

Session: All Meeting Posters Room: Exhibit Hall - Copper Lounge

Room: Room 1 - Big Butte/Highlands

PROXIMAL-TO-DISTAL FACIES TRENDS AND LARAMIDE TECTONIC INFLUENCE IN THE MOWRY SHALE, GREATER GREEN RIVER BASIN, WYOMING

Day/Time: Sunday, October 25, 10:35 am NOVEL GEOCHEMICAL METHODS FOR SWEET SPOT LOCATION AND QUANTITATION OF MOBILE OIL IN TIGHT, UNCONVENTIONAL ROCKS

Presenter: Greenhalgh, Brent (Wexpro Company) The Mowry Shale is an emerging unconventional resource play in the Powder River Basin (PRB), where recent drilling has demonstrated commercial oil and gas production despite challenges posed by bentonitic ash beds. Although the Mowry is stratigraphically continuous into the Greater Green River Basin (GGRB), the interval remains lightly explored there.

Presenter: Halpern, Henry (StratoChem Services) Co-authors: Hossam Ali, Yasmin, Kadry (StratoChem Services) Exploitation of oil from tight rock requires a deep understanding of the location and quantification of the mobile oil. Pyrolytic and extract chromatographic analysis of core and cuttings at surface conditions suffer from significant losses of in situ mobile hydrocarbons. Only the "residual mobile hydrocarbons" remain and uncertainties exist as to how to reconstruct these hydrocarbons back to stock tank oil volume. Two novel methods have been developed to (1) locate zones containing the highest probability of mobile hydrocarbons in the subsurface (Lokatur) and (2) reconstruction of the residual mobile hydrocarbons in the rock to in situ oil (Rek-On).

New high-resolution data from a complete core through the Mowry Shale in southwest Wyoming and two detailed measured sections along the northern flank of the Uinta Mountains in Utah significantly improve stratigraphic understanding in the GGRB. A regional west-to-east cross section documents pronounced stratigraphic thinning toward the Uinta Mountains, indicating that the Uinta uplift was active during Mowry deposition and influenced accommodation. The core-outcrop transect, oriented roughly parallel to published depositional dip, reveals systematic west-to-east facies changes. The westernmost section is characterized by high detrital silt content and low fossil abundance (scattered fish scales and minor inoceramids). The middle section contains the highest clay content and lowest biosiliceous content. The easternmost section is dominated by silica-rich mudrocks with abundant inoceramid and radiolarian fossils and the lowest clay content. This progression records an eastward decrease in terrigenous (deltaic) influence and a corresponding increase in openmarine, biosiliceous sedimentation.

Lokatur consists of the normalized summation of three pyrolytic quantities to determine the "Lokatur Oil Productivity Index (LOPI)". Rek-On is also pyrolysis-based and requires several proprietary steps and calculations to restore the Residual Mobile Hydrocarbons to stock tank barrels of oil per acre foot. These cost-effective methods will be discussed in detail with case studies. Session: New Developments in Unconventionals Room: Room 1 - Big Butte/Highlands Day/Time: Sunday, October 25, 8:35 am

These observations provide a predictive framework for comparing the Mowry Shale in the GGRB to the PRB and identifying the most prospective unconventional targets in the GGRB.

2026 RMS AAPG

43

BUTTE, MT

ABSTRACTS Pedogenic fabrics include preserved glaebules, slickensides, abundant root traces, and local bioturbation. Terrestrial organic debris is common and occurs mostly as mm-sized (or smaller) plant fragments. Mapped bentonites are restricted to individual ‘key beds’ that contain primary, undiluted eruptive-phase volcanic fall-out, including primary volcanic zircons that can be dated using U-Pb, preserved in an otherwise pure bentonitic clay. Only a small fraction of benonitic mudstones contain primary eruptive phase material in undiluted form which, when present and hand-trenched, is recognizable in the field as a waxy, olive green, translucent layer of clay usually only a few cm thick. We interpret the Hell Creek Formation in the map area to represent deposition on a low relief coastal plain that was dominated by floodplain fines. Major fluvial channels were isolated with steeply-incised banks and a sandy bedload and are interpreted to have undergone frequent avulsion. Muddy interfluvial regions contained abundant standing water and were highly vegetated.

MAPPING SEDIMENTARY LITHOFACIES AT 1:24,000 SCALE IN THE MAASTRICHTIAN HELL CREEK FORMATION, SOUTHWESTERN GARFIELD COUNTY, MONTANA Presenter: Hendrix, Marc (Department of Geosciences, University of Montana) Co-authors: Reece Holzer, Isaac Stark, Cael Odell (Department of Geosciences, University of Montana) We report initial results from1:24,000 scale geologic mapping of sedimentary lithofacies within the Maastrichtian Hell Creek Formation in southwestern Garfield County, Montana. The map area described herein is ~7 square kilometers (~2.75 square miles) and is located mostly on private land. Mapped lithofacies within the Hell Creek include sandstone, horizonated mudstone, silty carbonate, and volcanic bentonite. Mapped sandstone facies are channelized, fine upward from coarse- to medium-grained, are well-sorted, and display massive bedding, planar lamination, meter-scale trough cross-bedding, and current ripples. Reworked pedogenic carbonate nodules and pebble- to boulder-sized mudstone intraclasts are common, but extrabasinal pebbles or larger clasts are absent. Inclined heterolithic strata (IHS) are present locally in some channel sandstones, particularly those that are finergrained and smaller, but are generally lacking in the major channel sandstone fill deposits. Softsediment deformation is common in many, but not all, major channel sandstones and includes convoluted bedding with meter-scale vertical relief, oversteepened cross-bed foresets, and rare dish structures. Collectively, these features are interpreted to reflect seismically-induced sediment liquefaction. Mapped silty carbonate facies occurs both as meter-scale discontinuous beds and as more laterally continuous beds that commonly cap upward-fining channelized sandstone deposits. Observed structures include both current and wave ripples, planar lamination and, in places, abundant bioturbation and root casts. Mapped mudstone facies are silty, bentonitic, and pedogenic, with well-developed horizonation ranging from <1dm to >1m thick.

2026 RMS AAPG

Session: Rocky Mountain Petroliferous Basins: Colorado Basins Room: Room 1 - Big Butte/Highlands Day/Time: Monday, October 26, 10:35 am CORE OF THE CORE. EXPANDING THE PRODUCTIVE “CORE” OF THE PARKMAN SANDSTONE THROUGH DETAILED CORE ANALYSIS AND APPLICATION TO HORIZONTAL TARGETING AND WELL PERFORMANCE. Presenter: Hennes, Andrew M. (Rockies Resources LLC) Co-authors: Michael Hofmann (AIM GeoAnalytics) and Garth Hill (Rockies Resources LLC) The Upper Cretaceous Parkman Sandstone (PS) within the Powder River Basin (PRB), WY, has long been recognized and exploited as a significant oil resource. Prolific modern horizontal oil well development of the PS in Campbell and Converse Counties is largely limited to the youngest, most basinward sandstones of the section, which we

44

BUTTE, MT

ABSTRACTS Target Zone” well of the pad is the strongest performing well on a cumulative basis, largely due to lower decline rates, especially in days 100-400 of production. These production results support our hypothesis of the performance capability of low permeability sandstone reservoirs with smaller pore throats in an under-pressured reservoir. Further, these results provide a potential pathway for more optimal horizontal development and future exploration of the PS play.

interpret as a lowstand system tract (LST), placing relatively high energy sandstones furthest basinward; setting up a large-scale stratigraphic trap across the PRB. A 122 ft long whole rock core acquired in Campbell County in 2022 across this entire productive PS interval, including a portion of highstand sediments below and the sealing transgressive deposition above, is on display accompanying this paper. Detailed core and petrographic descriptions and core analysis, including MICP (Mercury Injection Capillary Pressure) identify a tri-mode of pore throats/permeabilities. The smallest pore throats range from ~0.01-0.05 microns as a result of near complete porosity occlusion by calcite. These pores are common throughout portions of the interval and do not show any distinct facies dependency. Of greater interest are the two other modes of pore throats that tie loosely to intensity of bioturbation and clay content. In cleaner, less bioturbated intervals the pore throat radius is ~0.75-3.0 microns with higher associated permeability, while in more clay rich, more heavily bioturbated samples the dominate pore throats range between ~0.08-0.75 microns. The two populations of larger pore throats are ubiquitously oil saturated in this core; the larger bi-mode of saturated pore throats are the dominant pores in the “Upper Target Zone” of this well, while the smaller of the saturated pore throat bi-mode dominates the “Lower Target Zone”. Both target zones exhibit significant hydrocarbon storage.

Session: All Meeting Posters (with core) Room: Exhibit Hall - Copper Lounge SUPPORTING CRITICAL MINERALS WORKFORCE DEVELOPMENT THROUGH UNDERGRADUATE COURSEWORK IN MINERALOGY AND IGNEOUS AND METAMORPHIC PETROLOGY Presenter: Hicks, Kate (Minot State University) Co-authors: Katherine McCarville, Kasidee Fuller, Bruce Toro, Travis Wennerholm, Isaac Keller, and Nikita Neyshtadt (Minot State University) Upper-division coursework in undergraduate geology degree programs provides an excellent opportunity to expose students to the importance of critical minerals, promoting workforce development in the industry. By focusing on suites of rocks from specific localities, students can place their observations and details within broader patterns of mineral occurrence distribution. Using this virtual “place-based” approach, rote memorization becomes less important as students spend more time practicing transferable skills including mineral identification and rock description in context, reviewing literature and potential hypotheses for layered intrusion formation, and ultimately extrapolating to an exploration activity. As an example, a recent class in igneous and metamorphic petrology had access to a donated diamond drill core from the JM Reef in Montana, a classic layered intrusion ore deposit which is actively mined by SibanyeStillwater. Curated selections of peer-reviewed articles, review articles, and guidebook literature were provided throughout the module. Each student logged the core, chose one or more

A six well pad of 1.5 mile PS horizontal wells was developed immediately offset to this cored well. One key aspect of drilling these offset wells was to test the hypothesis that landing in the “Lower Target Zone” could create a “better” well by directly accessing , through hydraulic fracturing, lower perm, high storage rock adjacent to the wellbore. Simultaneously, the upward propagating hydraulic fractures would still tap up into the higher perm “Upper Target Zone” counter to the conventional wisdom that the wellbore should be targeted in the “best rock”. All six wells on the pad confirm that the PS in this area is highly productive and all wells achieved excellent economic outcome. The Tenderfoot well, the single “Lower

2026 RMS AAPG

45

BUTTE, MT

ABSTRACTS distances to orogenic fronts. The intracratonic Williston Basin in north-central USA and southcentral Canada is no exception, and contains a Phanerozoic succession of sedimentary rocks of ~4.9 km thickness in the basin center. Accumulation of these sediments was largely in response to prolonged simple thermal subsidence. Intrabasinal structural highs and lows were active throughout the Phanerozoic suggesting overprinting of this simple subsidence model at times.

samples from which to cut thin sections, and described both hand specimen(s) and thin section(s) from their chosen sample(s). Further analysis of the Stillwater drill core using portable X-ray fluorescence (pXRF) gave students an opportunity to gain experience using technology relevant to the field of critical minerals development. The class met via teleconferencing with a development geologist working at the mine, learning about the mining process and various technologies used in the production of platinum group minerals. Students also viewed a recent webinar (sponsored by a professional organization) on how layered intrusions form, encountering not only ideas related to the geology but also the idea of professional societies and lifelong learning. In the culminating activity for the module, students were assigned a continent, asked to identify potential exploration targets, and provide evidence to support their claims. Inevitably, economic considerations and geopolitical implications arise offering further insight into the challenges of critical minerals development today.

In Late Devonian time the Williston Basin was located ~1000 km inland of the active margin. We propose that despite the long distance to the active margin, the latest Devonian sedimentary fill in the intracratonic Williston Basin provides a record of coeval continental margin development. This conclusion is drawn from a multi-proxy geochemical and sedimentological study of the lower Bakken Shale in the Williston Basin, that includes the detailed analysis of 22 cores and additional well logs from the Williston Basin in North Dakota and Saskatchewan, and extends into central northern Montana.

Session: All Meeting Posters

Our data from the Williston Basin implies that subsidence patterns during the deposition of the lower Bakken Shale varied significantly through time. We suggest that transition from a late collision to initial slab formation in the Kootenay arc region caused reactivation of basement structures in the Williston Basin and the formation of small sub-basins within this intracratonic sag. This is succeeded by a pattern of more uniform subsidence, that marks the southward migration of the collision front. Our model provides a recipe for using detailed, high-resolution studies of sedimentary deposits in an intracratonic basin to help reconstruct timing of an ancient orogen that was overprinted by subsequent orogenic activity, and highlight the potential of intracratonic basins as unique holistic repositories of cratonic evolution.

Room: Exhibit Hall - Copper Lounge THE WILLISTON BASIN'S TAKE ON LATE DEVONIAN CONTINENTAL MARGIN TECTONISM Presenter: Hofmann, Michael H. (AIM GeoAnalytics) Co-authors: Bruce S. Hart (University of Western Ontario) The record of Paleozoic orogenies along the western margin of North America are overprinted by younger tectonic events. Records collected in close proximity to the margin that were uplifted during the Mesozoic, and are easily accessible at the surface, received the strongest overprint. Thus, our knowledge of continental margin development that predate the prominent Sevier and Laramide orogenies is largely incomplete.

Session: Rocky Mountain Petroliferous Basins: Williston Basin

Intracratonic basins preserve a prolonged and largely undisturbed sedimentary and geochemical signal of the cratonic geologic history at a long

2026 RMS AAPG

Room: Room 1 - Big Butte/Highlands

46

BUTTE, MT

ABSTRACTS by stratigraphic position, samples from the upper Turner Sandstone almost uniquely contain type II quartz, while the rest of the Turner samples contain a mix of quartz that is near the average.

Day/Time: Monday, October 26, 8:35 am THE BLACK HILLS AS A SOURCE OF QUARTZ FOR THE TURONIAN TURNER SANDSTONE IN THE POWDER RIVER BASIN

By extending the SEM-PCL analysis to older sandstone units in stratigraphic and spatial proximity to the Turner Sandstone, we determined that the Turner Sandstone was primarily locally sourced from the underlying Albian Newcastle Sandstone. Type II quartz, the most common quartz type in the Turner Sandstone samples, is found in similar concentration (76-96% type II quartz) in samples from the Newcastle Sandstone samples. Spatial variations in quartz type composition in the Turner Sandstone mimic spatial variations of the Newcastle Sandstone quartz composition, further suggesting local sourcing of the Turner Sandstone.

Presenter: Hofmann, Michael H. (University of Montana) Co-authors: Carson Broaddus (ConocoPhillips), Amelia Fullwood (University of Montana), Grace Suden (GSI Environmental), Emma Braddock (Washington State University) The Turner Sandstone in the Powder River Basin (PRB) in Wyoming, USA, is one of the prolific Late Cretaceous reservoirs in the eastern PRB. The presence of ammonites of the Scaphites whitifeld ammonite zone place the sandstone firmly in the Upper Turonian. A similar ammonite record is present in rocks of the Wall Creek Member of the Frontier Formation along the western margin of the PRB, suggesting a near synchronous deposition of these two units. Petrographically these units are indistinguishable and comprise feldspatho-lithoquartzose sandstones. A host of workers have studied these rocks over many decades, but the depositional relationship between these two units remains enigmatic.

The results of our study propose the presence of a topographic high at the position of the present-day Black Hills, during a time of widespread marine transgression into the Cretaceous Seaway. Our work is intended to assist with paleogeographic reconstructions during the critical phase of basin development along the evolving Rocky Mountains and help shed light on a longstanding question about the depositional relationship between these two formations. Further, our work demonstrates the usefulness of an often overlooked and easy to use method in provenance studies.

Here, we present results from a comprehensive scanning electron microscope panchromatic cathodoluminescence (SEM-PCL) analysis of >2000 individual sand-sized quartz grains from cores and outcrops across the PRB. We combined SEM-PCL analysis with classic QFL investigation and detrital zircon analysis to provide insights on the provenance of these contemporaneous units. Our results show a clear demarcation between quartz types observed in the Frontier Formation and quartz types in the Turner Sandstone. The Frontier Formation comprises, on average, 72% quartz with an abundance of microfractures (Type I quartz), 11% monocrystalline quartz, commonly zoned, and without any notable fractures (Type II quartz), and 18% polycrystalline quartz with undulous extinction (Type III quartz). In contrast, the Turner Sandstone samples comprise, on average, 24% Type I quartz, 55% Type II quartz, and 21% Type III quartz. Importantly, when separated

2026 RMS AAPG

Session: Geochronology and Provenance Room: Room 2 - Kelley/Seward Day/Time: Sunday, October 25, 3:35 pm FLUVIAL SANDSTONES OF THE MAASTRICHTIAN HELL CREEK FORMATION IN SOUTHWESTERN GARFIELD COUNTY, MONTANA Presenter: Holzer, Reece (The University of Montana) Co-authors: Cael Odell, Isaac Stark, and Marc Hendrix (University of Montana) Although the Hell Creek Formation has long been famous for its dinosaur remains, the basic sedimentology of the formation as a whole is not well documented and the sedimentary controls on

47

BUTTE, MT

ABSTRACTS the deposition of the Hell Creek remain poorly understood. Our project addresses this gap through the mapping of lithofacies at 1:24,000 scale, covering approximately 0.7 square miles in quadrants 07 and 18 of the 14N, 36E quadrangle in Garfield County, MT. Six lithotypes were defined: bentonite, sandstone, carbonate, horizonated mudstone, Holocene alluvium, and Pleistocene terrace. onX software was used in the field to trace approximate contacts, and later refined on ArcGIS Pro to create a complete map in accordance with GeMS standards. Mapping reveals that sandstones in the study area are discontinuous, lenticular, and poorly cemented. Smaller sandstone bodies are fine-grained and show fewer cross-beds while large bodies are coarser, display soft-sediment deformation, massive bedding, large-scale trough cross-bedding (1–2 m of relief), ripples, and rip-up clasts. Sandstone channel deposits are mappable for <1 km before pinching out, ranging in width from 15–50 m and having thicknesses up to ~10 m. Carbonate-cemented sandstone concretions also appear as pipe-like bodies (2–15 m length, 1–3m width) with prominent cross-bedding, at the tops of sandstone channel deposits. Bentonite beds are truncated by sandstones, indicating channel incision into an existing floodplain. Bentonitic mudstones form extensive floodplain deposits and are characterized by popcorn weathering and pedogenic horizonization. Carbonate-cemented siltstones appear as interbedded layers in sandstones or as individual concretions, suggesting groundwater precipitation or ponding in the floodplain. Overall, the characteristics and distribution of sandstones in the study area indicate the presence of isolated channels characterized by frequent avulsion and a bentonite-rich floodplain with abundant standing water. These features are suggestive of a larger anastomosing system with avulsion driving sandstone architecture.

ORGANOFACIES VARIABILITY OF THE MOWRY SHALE ACROSS THE GREEN RIVER AND WIND RIVER BASINS: A LARGE PYROLYSIS DATASET FROM CORE, CUTTINGS AND OUTCROP Presenter: Hudson, Samuel M. (Brigham Young University) Co-authors: Brad Taylor, Austin Toner, Charles Kewish, McKay Morgan, Adam Gray, Kai Wegner, Trevor Tuttle, Blake Steeves (Brigham Young University), and Jonathon M. Sevy (Oxy) The Cretaceous Mowry Shale is a wellcharacterized, prolific source rock across much of Wyoming, and is increasingly becoming a potential unconventional reservoir target, particularly in the Powder River Basin of eastern Wyoming. While less attention has been paid to the Mowry within the Wind River Basin (WRB) and Green River Basin (GRB), detailed characterization of over 500 samples from outcrop, core and cuttings using pyrolysis and X-ray fluorescence as part of this study shows that it has excellent potential as an unconventional target in these basins as well. Samples analyzed as part of this study represent outcrop, core and cuttings, and the average total organic carbon (TOC) of all samples is 2.02% (±1.56%), with regional TOC values increasing basinward toward the northeast (up to a maximum of 7%). The majority of samples contain Type II/III to Type III mixed marine/terrestrial kerogens, with marine-dominance (Type II) also increasing basinward to the northeast. This increase in Hydrogen Index (HI) reflects a relative decrease in terrestrial organic matter (TOM) input moving away from paleoshoreline, though HI values show that terrestrial input is important even in the more basinal parts of the study area. The positive correlation between increasing TOC and increased HI shows that the algal, oil-prone kerogen component is a material contributor to the preserved organic carbon within the Mowry Shale moving eastward.

Session: All Meeting Posters Room: Exhibit Hall - Copper Lounge

2026 RMS AAPG

Similar to what has been reported in the Powder River and Bighorn basins, silica content is extremely high in the Mowry Shale, ranging between 70-90% SiO2 bulk weight based on XRF

48

BUTTE, MT

ABSTRACTS erosional remnants located along the east flank of the Cedar Creek Anticline, 25 to 60 miles (40 to 97 km) further south, beyond the generally accepted southern limit of the Bakken in the Williston Basin. The Bakken remnants, when present, are bounded by unconformities and preserved in local subbasins beneath the overlying subScallion/Lodgepole sequence boundary and rests on an angular unconformity eroded into Devonian and older strata. These Bakken remnants provide important insights into the extent of the original Bakken depositional system and the tectonic processes that occurred during and after deposition. We infer that these Bakken remnants correlate to the Upper Bakken Shale in the Williston Basin and the Cottonwood Canyon Member of the Lodgepole Formation in Wyoming.

analysis, and confirmed on a smaller subset of samples through XRD analysis. Thin section examination of select samples across the basin confirms that the high silica content is due to both detrital quartz and also biogenic quartz. Angular detrital quartz grains ranging in size from silt to very fine sand are present throughout all samples, while biogenic quartz is common only in more basinal samples, reinforcing a basinward deepening and an increase in the importance of algal organic material moving to the northeast. In addition, organic silica is often concentrated in discreet cm-scale intervals, and these are interpreted as likely storm beds enriched in transported radiolarians and other minor biogenic siliceous grains. The consistent dominance of silica, as well as a shift towards biogenic silica moving eastward, has important implications for the brittleness of the Mowry.

Strata within the Bakken remnant consist of two distinct lithologies. The lower interval is a thinbedded, black to dark gray, organically-rich, shale interbedded with thin, wispy, light-colored dolomite laminae. The off-scale gamma ray response and very high resistivities correlate with measured high TOC values (1.72 to 5.88 %) and Tmax values of 441℃ to 451℃ indicating the presence of a mature source rock. Thickness of this lower interval varies from 0 to 50 ft (0 to 15 m) thick. A lag deposit was observed at the base of the Bakken interval in a few of the cores and rests on strata ranging from Three Forks down through the Silurian Interlake Formation, depending on the location along the Cedar Creek Anticline. The underlying basal angular unconformity represents a set of merged sequence boundaries that include the unconformity at the top of the Three Forks and base of the Upper Bakken Shale observed along the margins and west of the Williston Basin..

Based on this work, we suggest that the rock properties of the Mowry Shale across much of Wyoming are favorable for further hydrocarbon exploration. Organic richness in the study area is similar to what is seen in the Powder River Basin, and mixed kerogen type prevalence suggests both oil and gas have been generated within both the Wind River and Green River basins. This large combined pyrolysis dataset from outcrop, core and cuttings shows trends that may high-grade exploration within central and western parts of the state. Session: Rocky Mountain Petroliferous Basins: Mowry Shale Room: Room 1 - Big Butte/Highlands Day/Time: Sunday, October 25, 11:00 am BAKKEN EQUIVALENT SHALES ALONG THE CEDAR CREEK ANTICLINE, MONTANA

The overlying second interval only occurs in association with the lower interval and ranges from 0 to 60 ft (0 to 18 m) in thickness. It consists of non-porous dolomite and limestone, as determined from density-neutron logs, and has a lower, on-scale gamma ray response. The variable thickness of the upper interval is attributed to truncation during an erosion event prior to deposition of basal Scallion Member of the Lodgepole Formation. In areas where the Bakken

Presenter: Hughes, Gary C. (Montana Bureau of Mines and Geology) Co-authors: Ted P. Doughty (PTD Geoscience) and Jay A. Gunderson (Montana Bureau of Mines and Geology) Black organically-rich Bakken shales occur as two separate and distinct (150,000 to 180,000 acres)

2026 RMS AAPG

49

BUTTE, MT

ABSTRACTS package, while high-porosity (PHIT) sands within the WLCK A parasequence appear as lowerimpedance zones within this body.

remnants are not present, the glauconitic packestones and grainstones of the Scallion carbonate bank facies rest on deeply eroded Devonian or older strata. Far field stresses associated with the Antler Orogeny led to localized highs (e.g., Central Montana Uplift, Cedar Creek Anticline) and lows (e.g., Cottonwood Canyon, Williston Basin) where deep incision and subsequent sporadic preservation of strata occurred.

PHIT maps delineate NNW-SSE sweet-spot trends in the Upper WLCK through two northern townships, with the Lower WLCK the primary target in the southwest townships. Fault imaging reveals primarily normal offset along near-vertical regional lineaments, with down-dropped blocks hosting thicker Upper Frontier sands. Ties to the sequence stratigraphic framework are robust, and clear imaging of high-PHIT zones combined with accurate depth conversion enables optimum well planning.

Session: All Meeting Posters Room: Exhibit Hall - Copper Lounge FRONTIER FORMATION PROSPECTIVITY IN THE SOUTHWEST POWDER RIVER BASIN: INTEGRATION OF 3D SEISMIC INVERSION, CORE-CONSTRAINED SEQUENCE STRATIGRAPHY, AND MACHINE LEARNING RESERVOIR CHARACTERIZATION

Machine Learning Reservoir Characterization Random Forest algorithms trained on upscaled elastic log data predict PHIT (R²=0.87), Vclay (R²=0.94), and Vquartz at 17-foot resolution across the 3D volume, sharpening facies discrimination and reducing targeting uncertainty across the survey footprint.

Presenter: Inks, Tanya L. (IS Interpretation Services LLC) Co-authors: Rex Stout (Sage Butte Energy LLC)

Core-to-Seismic Integration and Sequence Stratigraphic Framework

Background and Geological Setting

Fifteen conventional cores ground-truth the model. Key bounding surfaces—the Top FRNR Transgressive Surface of Erosion, the WLCK A Forced Regressive Surface of Erosion, and the Basal WLCK and Emigrant Gap Sequence Boundaries—are identified in core and propagated into the seismic. The Buttermilk pilot hole, which cored the complete FRNR and Emigrant Gap section and served as a key inversion well, confirms via FMI, sonic scanner, and CMR logs that the PHIT anomaly persists along proposed horizontal wellbore trajectories.

The Wall Creek (WLCK) member of the Frontier Formation (FRNR) in the southwest Powder River Basin (PRB) is a tight oil horizontal play marked by inconsistent production driven by complex, stratigraphically controlled fluid content. Historically overshadowed by the Frontier’s Turner Sand member, the WLCK exhibits distinct stratigraphic architecture governed by basement lineaments and syn-depositional faulting that impacted accommodation space, sand distribution, and reservoir quality throughout the Cretaceous (including the Sussex and Shannon sandstones). Most initial horizontal wells on the Sage Butte leasehold were drilled with suboptimal completion designs and inconsistent targeting.

Conclusions and Play Implications Integration of core-calibrated sequence stratigraphy, 3D seismic inversion, and machine learning demonstrates that the southwest PRB Frontier WLCK play is substantially de-risked in the area with seismic coverage, where predictable stratigraphy and mappable Wall Creek PHIT anomalies converge. Numerous probable horizontal locations have been identified on the Sage Butte leasehold, representing a mix of infill

3D Seismic Inversion and Attribute Analysis Merged and reprocessed pre-stack time migration (PSTM) data, over eight townships, were inverted to recover Acoustic Impedance (AI), Vp/Vs ratio, and density volumes at 17-foot vertical resolution. The Top WLCK interval images as a high-AI

2026 RMS AAPG

50

BUTTE, MT

ABSTRACTS structural position. Spatial relationships among these parameters define areas where favorable thermal and reservoir conditions overlap and provide a framework for interpreting productive trends within the basin. These results demonstrate the value of integrating petroleum-system, reservoir, and spatial datasets when evaluating unconventional shale resources and provide a basin-scale framework for identifying areas favorable for future Mowry Shale exploration and development.

and play-extension opportunities. This integrated workflow gives an objective, reproducible basis for DSU-level target selection and well placement that meaningfully reduces geologic risk across Sage Butte leasehold and potentially the broader western Powder River Basin. Session: Exploration Methods Room: Room 1 - Big Butte/Highlands Day/Time: Monday, October 26, 3:05 pm MOWRY SHALE GEOLOGY, SWEET SPOT DELINEATION, AND PRODUCTION EVALUATION IN THE POWDER RIVER BASIN, WYOMING

Session: Rocky Mountain Petroliferous Basins: Mowry Shale Room: Room 1 - Big Butte/Highlands

Presenter: Johnson, Matthew B. (School of Energy Resources, University of Wyoming)

Day/Time: Sunday, October 25, 11:25 am

Co-authors: Geoffrey Thyne (Esal), Grant Copeland and Jiao Zunsheng (University of Wyoming)

HYDROCARBON POTENTIAL AND ORGANOFACIES OF THE MOWRY SHALE: INTEGRATING ELEMENTAL GEOCHEMISTRY WITH PYROLYSIS

The Lower Cretaceous Mowry Shale is a regionally extensive, organic-rich, siliceous marine shale that represents both a major petroleum source rock and an unconventional reservoir in the Powder River Basin (PRB), Wyoming. Despite widespread hydrocarbon generation, production from the Mowry varies substantially across the basin, suggesting that multiple geologic and reservoir controls influence productivity.

Presenter: Kewish, Charles W. (Brigham Young University) Co-authors: McKay Morgan, Adam Gray, Brad Taylor, Austin Toner, Samuel Hudson, and Macy Lym (Brigham Young University); Jonathon M Sevy (Oxy) Pyrolysis is a simple, quick way to characterize both conventional source-rock candidates and unconventional reservoirs prior to more in-depth, targeted geochemical characterization of organicrich strata. Over 500 samples of the Cretaceous Mowry Shale have been analyzed using pyrolysis as part of a large-scale study across the Wind River and Green River basins, covering central and southwest Wyoming as well as parts of Utah and Colorado. Total organic carbon (TOC) across this sample set averages ~2% while hydrogen index (HI) values indicate mixed Type II/III kerogen. Enrichment in organic carbon occurs moving basinward to the northeast, and samples on average become increasingly Type III dominant, but the exact drivers for these trends are not welldefined through pyrolysis alone.

This study integrates subsurface well data, geochemistry, thermal data, reservoir pressure, structure, and production to evaluate regional controls on Mowry Shale petroleum occurrence and productivity. Corrected bottom-hole temperatures were used to characterize subsurface thermal conditions, while drill-stem test and pressure data were evaluated to identify regional pressure trends. Rock-Eval pyrolysis, total organic carbon, formation thickness, burial depth, and structural relationships were compared with hydrocarbon production to identify potential controls on productive areas. Results indicate that Mowry productivity cannot be explained by organic richness alone. Production is more strongly associated with the combined effects of burial depth, elevated subsurface temperature, reservoir pressure, and

2026 RMS AAPG

XRF analysis was performed on the majority of samples taken across outcrops, cores, and

51

BUTTE, MT

ABSTRACTS Subsurface porosity characterization provides foundational reservoir data for evaluating resource potential, storage capacity, and geologic suitability across a wide range of energy resources, including hydrocarbons, geothermal systems, mineral brines, hydrogen, and carbon capture, utilization, and storage (CCUS). Reliable porosity estimates are therefore essential for informed decision-making by federal agencies, academia, industry, and the public. Accurately characterizing porosity remains challenging where core and wireline data are sparse and reservoir lithologies are heterogeneous. In these settings, reproducible workflows that integrate petrophysical interpretation with available geologic data are needed to generate consistent, defensible porosity estimates while explicitly acknowledging data limitations and uncertainty. Here we present a case study in the Delaware Basin focusing on selected petroleum-bearing, CCUS, and enhanced oil recovery (EOR) formations. Two deterministic total porosity estimation methods — density-log porosity and the standard root-mean-square neutron-density, are evaluated using a limited suite of commonly available wireline logs (gamma ray, density, and neutron) and calibrated against available core data. Gamma ray logs are normalized and used for clay-volume assessment and core-to-log depth alignment. The methods are compared to determine which provides the most reliable and reproducible porosity estimates from a limited wireline log suite with the goal of developing a standardized workflow for regional resource assessments across multiple lithologies and energy-resource applications. This work provides a transparent, reproducible workflow for porosity estimation that establishes a consistent foundation for subsurface characterization across multiple energy resource applications. Preliminary results highlight the importance of rigorous data quality control and accurate matrix-density estimation as key factors influencing porosity calculations from limited wireline log suites. Initial comparisons also suggest that deterministic method performance varies with lithology, emphasizing the need for workflow flexibility rather than a single universally applicable

cuttings, and clear trends can be seen in the elemental geochemistry of the Mowry Shale. TOC preservation is often attributed primarily to anoxic conditions, but redox-sensitive ratios from this dataset suggest oxic to suboxic depositional environments throughout the study area. This suggests that organic carbon is preserved through rapid burial and/or high primary productivity rather than consistent anoxia within the Mowry Shale, which is an important distinction for interpreting source-rock potential. Thin section analysis and elemental data reveal a significant biogenic silica component (17–25%), supporting high productivity as an important contributor to organic accumulation and TOC preservation within the Mowry Shale. Elemental geochemistry also provides further understanding regarding organofacies and kerogen type, with Ti/Al ratios indicating higher detrital input in western and southern regions. This is consistent with paleoenvironmental interpretations of shoreline location, and reinforces the idea that there is a large-scale contribution of terrestrial material sourced from the proximal Sevier Orogeny, including associated terrestrial organic matter. This has important implications for generated hydrocarbons, dilution of organic material, and brittleness of potential unconventional prospects within the Mowry. Understanding these spatial and geochemical variations is essential for refining paleoenvironment reconstructions and improving subsurface predictions. Integrating pyrolysis with additional geochemical data allows for better predictive understanding of both spatial and temporal trends within the Mowry Shale, which has major implications for hydrocarbon exploration across the study area and beyond. Session: All Meeting Posters Room: Exhibit Hall - Copper Lounge BALANCING ACCURACY AND SCALABILITY IN POROSITY ESTIMATION FOR REGIONAL MULTIRESOURCE ASSESSMENTS Presenter: LaGesse, Jenny (U.S. Geological Survey, Central Energy Resources Science Center)

2026 RMS AAPG

52

BUTTE, MT

ABSTRACTS counts were too sparse for statistics, and corrections were applied by hand (fifteen parameters in the 1987 Eldingen survey). Heologic's Helium-DRI is taking lab like measurements at field level with the accuracy of 10,000’s ppm. This addresses each constraint: lab-grade in-situ measurement at 0.01 ppm sensitivity; multi-minute continuous flux readings per station, which discriminate quiet diffusive roof transfer (mapping the reservoir) from flow-driven conduit delivery (mapping the plumbing); end-toend digital capture with automated QC; and machine-learned inversion

approach. By documenting assumptions, applying standardized methods, and addressing uncertainty, the workflow reduces the potential for inconsistent interpretations, supports efficient future resource assessments, and provides a defensible framework for determining when additional characterization is warranted. Session: Subsurface Utilization Room: Room 2 - Kelley/Seward Day/Time: Monday, October 6, 11:25 am SCANNING EARTH'S HELIUM EXHAUST: DIGITAL GEOCHEMISTRY AS A PRE-SEISMIC SCREENING TOOL FOR CHARGED PETROLEUM, HELIUM, AND GEOTHERMAL SYSTEMS

calibrated against a global survey base. The technology has been deployed across +270 surveys within +20 countries, including operatorsupervised programs with PETRONAS, YPF, and Pan American Energy, the workflow reports 95% correlation with drilled outcomes and ~90% oilversus-gas discrimination, and the best part the costs of this survey is 10–25% the cost of 3D seismic.

Presenter: Lobreau, Dion (Pahvant Resources) Co-authors: Aaron Mattson (Mafic Consulting) and Denis Krysanof (Heologic Group) Helium is not a petroleum molecule, but a live petroleum system behaves as a helium collection machine, and that behavior is measurable at the surface. Radiogenic ⁴He is produced continuously and universally in the crust, gathered and transported regionally by deep groundwater, then partitioned preferentially out of water and into migrating oil and gas — The Hugoton-Panhandle complex is a basin-scale example. Within a trap, buoyancy organizes the acquired helium at the structural crest, pressed against the seal. A caprock that is an absolute capillary barrier to petroleum is not a barrier to the smallest atom in nature: helium transfers by diffusion at rates proportional to the escape pressure behind it, also known as the Helium flux, at a loss trivial to the reservoir but measurable above it. A charged, pressured, connected system therefore sustains an organized surface expression; an isolated residual accumulation decays toward background.

The method does not measure reserves or displace seismic. Helium digital geochemistry focuses on the most important aspects of Probability of Success: charge, timing and preservation. It reorders the cost of certainty — answering whether a structure is charged before significant capital is committed. Having the ability to say no to a prospect before seismic is shot, is the disruptor to conventional energy exploration. Session: Helium and Hydrogen Room: Room 2 - Kelley/Seward Day/Time: Monday, October 26, 9:00 am WHITE CANYON BANK - AN EXTENSIVE, PREVIOUSLY OIL-SATURATED PENNSYLVANIAN OOLITE DEPOSIT IN THE WESTERN PARADOX BASIN, SOUTHEASTERN UTAH Presenter: Matheny, J. Paul (Consulting Geologist)

Surface helium prospecting was field-tested by the USGS in 1976 and judged promising, then stalled for five decades — not on physics, but on practice: helium leaked from grab-sample bottles, sensitivity was marginal against signals of tenths of a ppm over a 5.24 ppm background, sample

2026 RMS AAPG

Co-authors: Brian, A. Hampton (Department of Geological Sciences, New Mexico State University) The Paradox basin has produced hydrocarbons since 1908, primarily from Pennsylvanian and

53

BUTTE, MT

ABSTRACTS penetrated, but unrecognized, in numerous wells drilled in the study area in the 1950s, 1960s and 1980s. As mapped, it is extensive – approximately 55 miles in length and 15 miles in width. Pore volume in this large bank is estimated at approximately 8 billion barrels. The oil that originally saturated the bank is believed to have migrated upward through the fractures and reaccumulated in the Permian White Rim Sandstone. Recognition of this extensive, previously oil-saturated, oolite bank in the Ismay provides a tangible and viable mechanism for sourcing the giant heavy hydrocarbon accumulation in the Tar Sand Triangle, which is the topic of a separate paper.

Mississippian rocks. Most of the production is from algal and bioclastic limestone and dolomite deposits in the Ismay and Desert Creek stages of the Pennsylvanian Paradox Formation. The discovery of Desert Creek field in 1954 and the giant Aneth Field in 1956 prompted widespread exploration drilling throughout the basin, including the study area in southeastern Utah, during the late 1950’s and 1960’s and again in the early 1980’s. Numerous significant but smaller accumulations were discovered but none on the scale of Aneth (EUR>450MMBOE) and nothing within or near the study area. The Pennsylvanian section contains numerous mature hydrocarbon source beds; however, the main challenge has been finding reservoir rock in the carbonate dominated Ismay and Desert Creek zones. In the early 1990’s a six-well wildcat drilling program was conducted in the White Canyon area approximately 50 miles west – northwest of the nearest production. While the program did not find anything anomalous in the Desert Creek, several of the wells encountered an oolite deposit over 20feet thick in the Ismay interval. Core taken through the oolite interval showed both matrix and oomoldic porosity were present. Uniform paleyellow fluorescence and residual live oil in the oomoldic pores were present in the freshly slabbed core. Total porosity exceeded 20 percent and reservoir properties based on core and log data are identical to those of productive oomoldic intervals in Aneth field. However, drill stem tests and completion attempts recovered only traces of oil and small volumes of fresh water so the wells were abandoned. Reservoir pressure was extremely low because the reservoir was breached by extensive fracturing during uplift of the Colorado Plateau. Absent encouragement for commercial development, geologic efforts were directed elsewhere, and a 30-plus year hiatus ensued before the project was revisited by this study.

Session: Uinta Basin 2: Green River and Paradox Resources Room: Room 1 - Big Butte/Highlands Day/Time: Monday, October 26, 1:40 pm A TANGIBLE AND VIABLE SOURCE FOR THE TAR SAND TRIANGLE, WESTERN PARADOX BASIN, SOUTHEASTERN UTAH Presenter: Matheny, J. Paul (Consulting Geologist) Co-authors: Brian, A. Hampton (Department of Geological Sciences, New Mexico State University) The Tar Sand Triangle (TST), located in the Paradox basin of southeastern Utah, is the largest heavy oil accumulation in the United States. It is estimated to contain 6.3 billion bbl. of heavy oil in place and may have originally contained 13-16 billion bbl. before biodegradation, water washing and erosion occurred. Heavy hydrocarbons are contained in the Permian White Rim Sandstone, and the physical deposit is well documented by many authors. Historically the source of the oil and the migration route have been unclear and continue to be topics of investigation. Several authors have proposed possible sources and all except one require long distance migration via complex migration pathways. This paper presents evidence that the Pennsylvanian Paradox Formation is a viable source of some, if not all, of the oil in the TST. An extensive oolite deposit, informally

The significance of this once oil-saturated oolite deposit was only partially recognized initially. Recent examination of publicly available core, log, cuttings, DST, and completion data in this area shows that the Ismay oolite deposit was

2026 RMS AAPG

54

BUTTE, MT

ABSTRACTS researchers are often left with highly fragmented datasets of varying quality and often reproduce previously published work without realizing it. To highlight these problems and illustrate the power of data mining, a workflow has been created and applied to the Mesaverde Group of the Piceance Basin, Colorado.

designated the White Canyon Bank, has been identified in the Ismay Stage of the Paradox Formation underlying the southeastern part of the TST. As mapped, the White Canyon Bank is approximately 55 miles long, 15 miles wide and has a pore volume of approximately 8 billion barrels. The Bank began to fill with oil at approximately 75 Ma. The oil was sourced by the organic-rich Gothic Shale and possibly also by the Chimney Rock Shale. Both shales immediately underlie the Ismay and are the sources for the majority of the oil produced in the basin to date. At 25 Ma the Colorado Plateau began to rise and generation ceased. Uplift was accompanied by normal faulting and extensive fracturing in the vicinity of the White Canyon Bank and the TST. When fractures breached the Bank, accumulated oil leaked approximately 3000 ft vertically through the overlying Honaker Trail, Elephant Canyon, Cedar Mesa and Organ Rock intervals and into the White Rim Sandstone where it accumulated. The Moenkopi Fm overlying the White Rim is believed to be ductile enough that it was unaffected by fracturing and continued to provide a top seal for the accumulation in the White Rim.

Through an extensive literature search, ammonite fossil localities, stratigraphic sections, subsurface correlations, and geologic maps for ten chronostratigraphic units were tabulated and integrated using spreadsheets and a business analytics software package. These units included: (1) Desert Member, Blackhawk Formation /B sandstone of Dyni (1968)/Morapos Sandstone; (2) Castlegate Sandstone/Mancos A; (3) Loyd Sandstone/Buck Tongue Sandstone; (4) Upper and Lower Sego Sandstone; (5) Corcoran Sandstone; (6) Cozzette Sandstone; (7) Rollins Sandstone/Trout Creek Sandstone; (8) Middle Sandstone; (9) Upper Sandstone; and (10) Lion Canyon Sandstone. The data were then overlain to define an initial area-of-interest (AOI) per unit and a subsurface geological model was created by replicating previously published well log correlations. The correlations were then integrated with outcrop data by creating a cross section grid tied to stratigraphic sections. Geologic maps were utilized simultaneously to guide well log correlations, and ammonite fossil localities were employed to troubleshoot incorrect correlations and standardize interpretations. Once a satisfactory answer was reached, the AOI was infilled and expanded with additional data.

Session: Uinta Basin 2: Green River and Paradox Resources Room: Room 1 - Big Butte/Highlands Day/Time: Monday, October 26, 2:05 pm INTEGRATING 100 YEARS OF RESEARCH IN THE MESAVERDE GROUP, PICEANCE BASIN, COLORADO, USA Presenter: McDowell, Bryan P. (Colorado School of Mines & Sabata Energy Consultants)

Gross sandstone thickness maps based on the newly created chronostratigraphic framework reveal a complex history of sandstone distribution over 5 m.y. Apparent shoreline rotation and compensational deposition superimposed on conventional transgressive/regressive cycles suggest irregular movement from early Laramide structures as early as the Campanian. This interpretation is further supported by eastern Cretaceous-aged intrusions and their cross cutting relationships, possibly associated with the Colorado Mineral Belt.

Co-authors: Piret Plink-Bjorklund (Colorado School of Mines) Like much of the Western Interior Basin, the Mesaverde Group of the Piceance Basin, Colorado has been highly studied for over 100 years by academia, geological surveys, government, and industry. Ongoing digitization efforts make this data much easier to access than before; however, utilization is still difficult due to the text- and figure-based nature of geologic data. As a result,

2026 RMS AAPG

55

BUTTE, MT

ABSTRACTS Medicine Hat Block, and Great Falls Tectonic Zone. While some sample localities match the underlying basement signal and therefore reflect a local source, others have a mixed provenance signature and require more complex sediment routing with mixing of both local and distal sources. Our ongoing work integrates quantitative detrital zircon comparison using multidimensional scaling analysis, forward mixture modeling, and non-negative matrix factorization, with forthcoming U-Pb detrital monazite, additional zircon Hf, and regional stratigraphic correlation of new and published data from the Flathead Sandstone, Belt Supergroup, and other potential sources to untangle its complex provenance. In turn, we seek to interpret these datasets to refine the paleogeography and tectonics of the early Cambrian in the Northern Rocky Mountains.

Session: Rocky Mountain Petroliferous Basins: Colorado Basins Room: Room 1 - Big Butte/Highlands Day/Time: Monday, October 26, 11:00 am INSIGHTS INTO PALEOGEOGRAPHY AND DEPOSITIONAL CHARACTERISTICS ATOP THE GREAT UNCONFORMITY IN WESTERN MONTANA, USA: ZIRCON U-PB-HF AND MONAZITE U-PB CONSTRAINTS FROM THE CAMBRIAN FLATHEAD SANDSTONE Presenter: Moll, Joseph R. (Department of Earth Sciences, Montana State University) Co-authors: Devon, A. Orme (Department of Earth Sciences, Montana State University), Daniel T. Brennan (Montana Bureau of Mines and Geology, Montana Tech) The Early Cambrian Flathead Sandstone (~510– 505 Ma) records the initial transgression of epeiric seas across Laurentia following the breakup of Rodinia. In Montana, the Flathead Sandstone was unconformably deposited on Paleoproterozoic and Archean metamorphic rocks or Mesoproterozoic Belt Supergroup strata and overlies the Great Unconformity. Due to the coarse, predominantly feldspathic pebble conglomerate present at its base, the Flathead is commonly interpreted to reflect local derivation from underlying basement and from recycling of the Belt Supergroup. Field investigations have documented that the Flathead’s basal conglomerate varies in thickness and coarseness, suggesting an irregular paleosurface atop the Great Unconformity. Our new and compiled detrital zircon U-Pb geochronology from the Flathead Sandstone reveal a variable Archean age component (>2.5 Ga) and a consistent Paleoproterozoic age component (~1.78 Ga). Epsilon-Hf results of a subset of these analyses have +10 to -15 isotopic values in both the Proterozoic and Archean U-Pb age components, with the Archean ages showing an increasingly evolved/more negative trend through time. These results overlap considerably with multiple potential first- and second-cycle source rocks including the Belt Supergroup, Wyoming Craton,

2026 RMS AAPG

Session: Geochronology and Provenance Room: Room 2 - Kelley/Seward Day/Time: Sunday, October 25, 4:00 pm NEW SEDIMENTOLOGIC AND GEOCHRONOLOGIC RESULTS FROM PALEOGENE LACUSTRINE STRATA AT BEAVER CREEK, WEST-CENTRAL MONTANA Presenter: Moore, Kallie (University of Montana Paleontology Center) Co-authors: Marc S. Hendrix (Department of Geosciences, University of Montana) We report preliminary results from sedimentologic investigation of a small exposure of fossiliferous Paleogene-aged nonmarine sedimentary strata preserved along North Beaver Creek Road near Lincoln, Montana. The nonmarine section at Beaver Creek is about 10 m thick and includes coal, organic-rich mudstone that is commonly laminated, siltstone, and bentonitic mudstone, all interpreted to be lacustrine in origin. Many of the organic rich laminated mudstones contain fossil plants, invertebrates, and vertebrates with carbonized soft tissues. Previous workers have proposed depositional age ranging from late Eocene to early Miocene for the Beaver Creek

56

BUTTE, MT

ABSTRACTS observe trends across Scout’s acreage. Key XRF observations along this west to east trend include:

strata, based on the recovery and identification of plant fossils. We report new U-Pb ages on primary, eruptive phase zircons recovered from four separate bentonite layers within our measured stratigraphic section and dated using LA-ICPMS facilities at Boise State University. Across the four samples, 166 zircon grains were dated. From stratigraphically lowest to highest (oldest to youngest), dates U-Pb dates were 39.5 ± 1.0 Ma; 39.1 ± 1.0 Ma; 38.9 ± 1.0 Ma; and 37.8 ± 1.0 Ma and are interpreted as being syndepositional. These results constrain the Beaver Creek section to the late Eocene and indicates that tectonic extension had begun in this part of western Montana by this time. The dates also indicate that the Beaver Creek section is chronologically equivalent to the Climbing Arrow Member of the lower Renova Formation.

1) Decreasing Calcium/Aluminum (Ca/Al) Ratio: Indicates a shift from biogenic carbonate to more terrigenous sediment source. 2) Constant Silica/Aluminum (Si/Al) Ratio: Suggests a steady sediment source into the basin. 3) Increasing Rubidium/Aluminum (Rb/Al) and Potassium/Aluminum (K/Al) Ratios: Indicates a higher abundance of K-bearing clays (Illite) eastward. 4) Increasing Manganese/Strontium (Mn/Sr) Ratio: Indicates higher degrees of diagenetic alteration eastward. 5) Abrupt decrease in Strontium/Barium (Sr/Ba) Ratio: Marks a transition into freshwater. 6) Increasing Iron/Manganese (Fe/Mn) Ratio: Indicates a transition into more reducing (anoxic) bottom water conditions.

Session: Montana Energy Resources and Geology Room: Room 2 - Kelley/Seward Day/Time: Monday, October 26, 3:05 pm GEOCHEMICAL MAPPING OF THE CALIFORNIA RIVER PROTODELTA USING HIGH-RESOLUTION XRF FROM HORIZONTAL WELLS: GREATER MONUMENT BUTTE UNIT, UINTA BASIN

Together, these six trends show that as Scout’s drilling expands eastward, the target bench is undergoing a depositional shift caused by an influx of freshwater and associated sediments into the basin. These observations help to define the extent of the depositional influence of the previously mapped California River Protodelta. Additional integration with production volumes is underway and will provide insight for acreage quality determination.

Presenter: Moreland, Travis W. (Scout Energy Partners) Scout’s Greater Monument Butte Unit (GMBU) position, along the southern rim of the Uinta Basin horizontal fairway, has seen rapid horizontal development over the past three years. As of the 2026 RMS conference, roughly 50 horizontal wells have been drilled within the Uteland Butte Member of the Green River Formation; mostly targeting the Uteland Butte D-Bench. This has provided a large volume of data within a narrow depositional package (~40’). A novel data integration method was created, pairing the X-Ray Fluorescence (XRF) analysis on cuttings, with detailed geosteering. This allowed for placement of each sample collected into well-defined ~2-4’ layers, capturing detailed lateral variations in the depositional environment. Calibrated XRF measurements were plotted from west to east to

2026 RMS AAPG

Session: Exploration Methods Room: Room 1 - Big Butte/Highlands Day/Time: Monday, October 26, 3:30 pm CONTRASTING CONTEMPORANEOUS DEPOSITIONAL SYSTEMS IN THE MAASTRICHTIAN LEWIS SHALE: WASHAKIE BASIN, CHEROKEE RIDGE, AND SAND WASH BASIN, GREATER GREEN RIVER BASIN Presenter: Nell, Mark M. (Wexpro Company) Co-authors: Zane Jobe (Colorado School of Mines)

57

BUTTE, MT

ABSTRACTS Room: Room 2 - Kelley/Seward

The Lewis Formation of the Washakie Basin has long been interpreted as a deepwater, turbiditedominated system deposited along the western margin of the Cretaceous Western Interior Seaway. In contrast, the Lewis Formation in the adjacent Sand Wash Basin and the depositional significance of the Cherokee Ridge remain comparatively poorly constrained. Existing depositional models generally treat the Cherokee Ridge as the distal continuation of the Washakie deep-water depositional system. However, integrated well-log correlations, regional seismic interpretation, stratigraphic mapping, and organic geochemical data presented here indicate that the Cherokee Ridge and northern Sand Wash Basin represent a distinct depositional domain rather than simply the toe of the Washakie slope. The Washakie Basin is interpreted to have remained a steep, tectonically influenced, bypass-dominated slope feeding basin-floor fan complexes, whereas the Cherokee Ridge–Sand Wash transition is characterized by lower gradients, reduced accommodation, lower sediment supply, and greater current and storm reworking. The Cherokee Ridge likely functioned as a subtle bathymetric high or zone of reduced accommodation that directed sediment derived from the Sand Wash margin into the distal southeastern Washakie Basin. This process-based depositional model explains anomalous Lewis isopach trends, complex log correlations, and regional facies transitions by recognizing the Cherokee Ridge as a sediment-routing partition between contemporaneous depositional systems. Total organic carbon (TOC) and Rock-Eval data further support this depositional model by demonstrating enrichment within both distal basin-floor and slope/prodelta environments in the Washakie Basin, with a similar enrichment trend observed within the interpreted Sand Wash slope/prodelta system. The resulting interpretation provides an updated regional framework for understanding Lewis stratigraphy, reservoir distribution, and unconventional exploration in southwestern Wyoming and northwestern Colorado.

Day/Time: Sunday, October 25, 2:35 pm EVOLUTION AND EXPANSION OF THE BAKKENTHREE FORKS HYDROCARBON PLAY Presenter: Nesheim, Timothy (WB Geological Consulting LLC) The Bakken-Three Forks Petroleum System has been commercially producing hydrocarbons within the Williston Basin for over 70 years. Periodic technological advancements continue to reinvigorate and expand the Bakken-Three Forks play. Oil & gas production from the Bakken-Three Forks began with vertical wells targeting natural fractured reservoir along the Antelope anticline during the 1950’s. The introduction of horizontal drilling in the late 1980’s led to a play development targeting naturally fractured Upper Bakken shale along the southwestern margins of the formation’s subsurface extent. Horizontal onemile wells targeting the Middle Bakken, completed with single-stage hydraulic fracture stimulations, led to the discovery and development of the Elm Coulee Field (eastern Montana) in 2000 and the Parshall Field in 2006 (western North Dakota ). Starting in the late 2000’s, two-mile laterals completed with multi-stage hydraulic fracture stimulations expanded exploration and development targeting the Middle Bakken reservoir between Elm Coulee and Parshall fields. Oil accumulations were also discovered and developed in the underlying Three Forks Formation during that same time frame. During approximately 2000-2020, portions of the Bakken-Three Forks play were drilled and tested across eastern Montana and western North Dakota, yielding commercial oil production from multi-stage hydraulically fractured two-mile laterals, but at sub-economic production rates that did not warrant developmental drilling. Another round of technological advancements has led to another expansion of developmental drilling in the Bakken-Three Forks play. BakkenThree Forks wells are now commonly drilled with 3-mile to 4-mile laterals completed with hydraulic fracture stimulations that outperform offsetting

Session: Sedimentology and Stratigraphy

2026 RMS AAPG

58

BUTTE, MT

ABSTRACTS district, the Burke and Revett formations in the Plains area cannot be differentiated in terms of facies or lithology. The local Ravalli Group is more accurately described as three fining-upwards (or deepening) facies successions. The Piegan Group, above the Ravalli Group, also contains predictable facies successions but cannot be effectively split into distinct mappable units. In response to these limitations, internal contacts were used to mark facies succession breaks where possible. While these internal contacts can be used to trace a particular stratigraphic position, they do not separate mappable stratigraphic units because the lithologies and facies on either side lack unique unit descriptions.

legacy 2-mile wells based upon oil production per foot rates. These drilling and completion improvements have led to yet another reinvigoration of the Bakken-Three Forks play. Session: Rocky Mountain Petroliferous Basins: Williston Basin Room: Room 1 - Big Butte/Highlands Day/Time: Monday, October 26, 9:00 am NEW GEOLOGIC MAPPING IN THE PLAINS, MONTANA AREA: STRATIGRAPHIC AND STRUCTURAL FINDINGS IN THE CENTRAL BELT BASIN Presenter: Parker, Stuart D. (Montana Bureau of Mines and Geology)

The structure of the map area highlights the transition from the Libby Thrust Belt in the north, to the Lewis and Clark tectonic zone (aka Lewis and Clark Line) in the south. We locally define the leading thrust of the Libby Thrust Belt at its southern margin: the Lynch Creek Thrust. Near the southern tip, the Lynch Creek Thrust consists of oblique footwall and hanging-wall ramps. The trace of the fault curves to match the trend of the Lewis and Clark tectonic zone. Exhumation increases and slip diminishes towards the southern fault tip, signifying uplift on a deeper structure: the Plains anticline. This interesting relationship suggests that structures of the Lewis and Clark tectonic zone may be more deeply detached than those of the Libby thrust belt and that oblique thrust ramps may be underappreciated. These interpretations refine working models of the Belt basin and underscore the need for ongoing mapping.

Co-authors: Jeffrey D. Lonn (Montana Techinological University) The Belt Supergroup is an incredibly thick (>18 km, 60,000 ft) package of low-grade metasedimentary rocks that covers much of the northern US Rockies. Mesoproterozoic Belt strata hosts significant ore deposits, including Ag-Pb-Zn deposits of the Coeur d’Alene mining district along the Idaho-Montana border and the Sullivan mine in southern British Columbia. Historical and future success in these mining districts requires predictive stratigraphic and structural models of the Belt basin. At present, our working models are limited by a general lack of detailed (>1:250,000 scale) mapping in the central part of the basin near Plains, Montana. To address this ongoing need, the Montana Bureau of Mines and Geology began mapping the Polson 30' × 60' quadrangle in 2023. This poster presents recent 1:24,000-scale mapping results from two 7.5’ quadrangles in the southwestern corner of the Polson project. We document nearly 10 km (32,000 ft) of Belt stratigraphy from member F of the Prichard Formation of the lower Belt, to the Snowslip Formation of the lower Missoula Group. We find that the Burke and Revett formations of the Ravalli Group, which host stratabound Cu-Ag deposits in the region, are nearly twice as thick as previously noted in the Plains area. In contrast to the type sections in the Coeur d’Alene mining

2026 RMS AAPG

Session: All Meeting Posters Room: Exhibit Hall - Copper Lounge RESERVOIR THERMAL ENERGY STORAGE IN EXTENSIONAL ENVIRONMENTS: INSIGHTS FROM NATIONAL ASSESSMENT EFFORTS Presenter: Pepin, Jeff D. (U.S. Geological Survey, Central Energy Resources Science Center) Co-authors: Erick R. Burns and Ryan C. Cahalan (U.S. Geological Survey)

59

BUTTE, MT

ABSTRACTS Session: Geothermal Resources

Storing thermal energy underground for later use in electricity production or direct-use heating/cooling is a promising green energy option. Reservoir thermal energy storage (RTES) is one such approach that stores energy in underutilized permeable strata with low ambient groundwater flow rates and more geochemically evolved waters (for example, brackish/saline) relative to overlying aquifers. The U.S. Geological Survey is assessing the national potential of RTES by focusing on five generalized geologic regions in the United States: Basin & Range, Coastal Plain, Illinois Basin, Michigan Basin, and Pacific Northwest. Reservoir models are developed for the following eight metropolitan areas to evaluate RTES performance across different climates and subsurface environments: Albuquerque, New Mexico; Charleston, South Carolina; Chicago, Illinois; Decatur, Illinois; Lansing, Michigan; Memphis, Tennessee; Phoenix, Arizona; and Portland, Oregon. Evaluated metrics include required well spacing, thermal storage capacity, and thermal recovery efficiency through time. Potential complicating factors considered for each reservoir include reservoir depth, free convection, and groundwater salinity. This work focuses on direct-use cooling because the need for cooling representative modern office buildings (25,000 square-feet, two stories) greatly exceeds that for heating in most parts of the country; however, the evaluated metrics are also relevant to heating and electricity applications. Results indicate that favorable RTES conditions exist in every region, with the Coastal Plain and Basin & Range being particularly favorable for thermal storage capacity, while the Pacific Northwest and Michigan Basin excel at energy recovery for the evaluated cooling application. The results underscore the utility of developing maps of thermal storage capacity, subsurface temperature models, and volumetric estimates of thermal storage capacity to serve as potential key RTES resource classification standards. Overall, this pre-assessment provides an initial understanding of RTES potential in several cities and geologic regions throughout the country and could aid further evaluation of national RTES efficacy.

2026 RMS AAPG

Room: Room 2 - Kelley/Seward Day/Time: Sunday, October 25, 9:25 am ANTHROPOGENIC TRACERS IN NORMANDY AND SAIPAN: MODERN COASTAL PROCESSES AND IMPLICATIONS FOR THE CRETACEOUS INTERIOR SEAWAY Presenter: Ramirez, Kassandra I. (Brigham Young University) Co-authors: Sydney Crockett, Samuel M. Hudson, Kai Wegner, Julie Robinson, Olivia J. Tatum, Brad Taylor, Austin Toner (Brigham Young University) Anthropogenic materials preserved in modern sediments provide a unique opportunity to study sediment transport, deposition, reworking, and preservation because their sources and ages are often known. Understanding these processes provides context for interpreting ancient depositional systems, including the Cretaceous Interior Seaway (CIS), which covered much of central North America during the Cretaceous. Variations in sediment supply, water depth, shoreline position, hydrodynamic energy, and reworking influenced sediment accumulation and preservation within the CIS. However, reconstructing depositional rates and sedimentary processes from the ancient rock record is difficult because deposits commonly reflect erosion, reworking, condensation, and time averaging. This study investigates modern anthropogenic metal as a sedimentary tracer and develops modern analogs for interpreting ancient marine environments. World War II-related metallic debris provides an effective modern tracer because it was introduced during a well-constrained historical event. We compare ferrous shrapnel distribution in two contrasting coastal environments: the siliciclastic beaches of Normandy, France, and the carbonatedominated shallow-marine environment of Saipan. In Normandy, more than 300 samples were collected across Utah, Omaha, Gold, Juno, and Sword beaches. Samples were dried, homogenized, sieved into four grain-size fractions,

60

BUTTE, MT

ABSTRACTS Appraisal and development of a large Pliocene lacustrine evaporite sequence in Railroad Valley, Nevada has delineated more than 20 billion tons of commodity salts buried between 1,000 – 2,800 feet below the surface of the playa. About 50% of the deposit is not yet evaluated, nor has the base been defined. The major salts and metals found include trona (Na2CO3), thenardite (Na2SO4), potassium, boron, lithium, and tungsten. A new lithium-borate mineral has been identified, and we propose the name “Loomisite” for this.

and magnetically separated to identify ferrous material. Shrapnel averaged approximately 0.4 wt.%, substantially lower than previous estimates of ~1 wt.%. Shrapnel is broadly distributed and preferentially associated with very fine- to finegrained sediment. Concentrations generally decrease above the high-tide mark as sediment becomes coarser, demonstrating the influence of tidal processes, grain-size sorting, erosion, and deposition. Saipan provides a contrasting example of localized anthropogenic input. Samples were collected at approximately 4 m intervals from the WWII Shoan Maru wreck in Tanapag Lagoon. Shrapnel concentrations are highest near the wreck and decrease rapidly within approximately 40 m. Sediments surrounding the Shoan Maru contain locally high concentrations of shrapnel, reaching ~8 wt.%. These patterns reflect pointsource input, storm-driven reworking, carbonate sediment production, and metal degradation.

The salt complex is bounded by clay beds, which are absent within the deposit over the central 50 square miles. The main body of salt contains hundreds of feet of pure “icicle” variety that is particularly water soluble. ICP measurements of lithium are as high as 1,100 ppm, and average 600 ppm in the lower salts. Boron ranges up to 27,000 ppm. Tungsten ranges up to 6,008 ppm. Trona purity ranges from 30% to 100%, and potassium is 4% or more over large intervals. The deposit is delineated by 45 oil wells with advanced geophysical logs. More than 38,500 feet of cuttings from these wells have been measured by ICP analyses. 3PL has drilled and cored four additional wells, and run numerous studies on a 1foot interval throughout the deposit. These tests include ICP, XRF, LIBS, XRD, Raman, solubility, and petrographic studies. Strata are defined by 22 members that show geochemical maturity as the deposit developed over time. Each member has been mapped and illustrated with cross sections. Other geophysical data further define the deposit, including 28 miles of magnetotelluric data, 98 miles of seismic data, and a seismic 3D survey. Advanced processing of 300-fold seismic data with acoustic-impedance inversion methods clearly delineates individual salt bodies.

The contrasting distributions demonstrate how depositional environment, sediment texture, hydrodynamic energy, and source characteristics control anthropogenic tracer preservation. Because the timing of the WWII event is known, its distribution provides a modern framework for evaluating sediment dispersal, reworking, burial, and relative depositional rates. These observations provide a modern analog for interpreting sedimentary records of the CIS and may improve estimates of sediment residence time, depositional rates, and preservation of event-related deposits within ancient marine systems. Session: New Developments in Unconventionals Room: Room 1 - Big Butte/Highlands Day/Time: Sunday, October 25, 9:00 am

Deposition of the richest portion of the salts has been controlled by active tectonics which have shifted the depocenter with time. Clearly delineated thrust faults imaged on the seismic data define the eastern boundary of the basin. Ancient shorelines indicate the closed basin shoreline was more than 1,200 feet higher than previously mapped, and thus the original lake was

APPRAISAL OF A SUPER-GIANT SODIUM, LITHIUM, BORON, AND TUNGSTEN SALT COMPLEX IN CENTRAL NEVADA Presenter: Ramirez, Vincent (3PL Operating Inc.) Co-authors: Karen Loomis (3PL Operating Inc.)

2026 RMS AAPG

61

BUTTE, MT

ABSTRACTS There is limited information about the Butte Oil #1 well in the Montana Board of Oil and Gas well files. What was known about the well was found in a few published reports that included:

enormous in size. We have named this Lake Livada and it covered the Great Basin area four million years ago. Many of these shorelines have been interpreted as active faults by other geologists. Gravity anomalies in Railroad Basin do not align concentrically with the deposit.

·

This project is designed for solution mining extraction. An extraction facility has been designed with large throughput that is similar to the larger mines in Wyoming. In addition to the trona product from these mines, 3PL is planning to produce significant quantities of potassium, sodium sulphate, boron, lithium, and tungsten.

· · ·

Session: Critical Minerals

The Butte Oil #1 well was drilled by the Butte Oil Company in late October 1901 and reached a reported depth of 1,450 feet (ft) by late 1902, where very hard “black limestone and iron” was encountered, possibly one of the of the Belt Series (USGS, 1963, MGS, 1984). According to Erdmann, USGS 1963, gas was discovered at 720 ft, which is said to have burned with a 4-foot flame at the well head.

Room: Room 2 - Kelley/Seward Day/Time: Sunday, October 25, 11:25 am PLUGGING MONTANA’S FIRST OIL WELL, THE BUTTE OIL #1, LOCATED IN GLACIER NATIONAL PARK Presenter: Reichhardt, David (Montana Technological University) Co-authors: Todd Hoffman (Montana Technological University) and Mary North-Abbott (MANA Consulting)

The 1984 MGS publication references Johnson, 1913, who visited the well sometime prior to 1913 and describes “a very considerable amount of highly inflammable gas bubbling up through the water in the well, and sufficient quantity so that the ignition of the gas shoots a flame two to three feet above the top of the casing. This persists for a few moments, and then goes out, but after about a minute can be relighted”. The 1984 MGS publication

Under the Bipartisan Infrastructure Law (BIL), also known as The Infrastructure Investment and Jobs Act, which was signed into Law November 15, 2021, the United States National Park Service (NPS) received funding for projects that address environmental and infrastructure concerns in the national parks, including wildland fire safety and restoration efforts, climate crisis intervention, legacy pollution eradication, and transportation enhancements. Subsequently, the NPS identified a number of legacy oil and gas wells for plugging and abandonment. Among those was the first oil well drilled in Montana, the Butte Oil #1, located in a remote area of northwestern Glacier National Park (GNP) adjacent to the head of Kintla lake. In the Fall of 2023, the NPS approached the Montana Tech Petroleum Engineering department to plan and contract out the Butte Oil #1 plugging and abandonment.

2026 RMS AAPG

Northwest Montana and Adjacent Canada, Montana Geologic Society 1984 Field Conference and Symposium; Mineral and Water Resources of Montana, USGS and MBMG Special Publication 28, May 1963; Montana in the Geologic Past, MBMG Bulletin 26, Eugene S. Perry, March 1962; and The Kintla Lake area ranger station logs.

includes a narrative by the author (Boberg) who visited the well in the 1950’s and recalled that “the casing was open to the surface and stood three feet above the ground. The caving in the hole had stopped the water flow as well as most of the gas flow as observed by Johnson but matches thrown into the casing would fall a ways and then explode, sounding a hollow “whump.” Boberg returned to the site in 1982 and noted the well was not evident and the casing had been “broken in and beat to the ground and covered with a stone to conceal its presence.” Montana Tech and the NPS conducted a site visit in August

62

BUTTE, MT

ABSTRACTS bid. The site visit was held in May, 2025. Seven potential contractors attended the pre-bid site visit. Subsequently, Montana Tech contracted with Liquid Gold Wells

2024 and found the well in the same condition as described by Boberg in 1982. Montana Tech and GNP personnel conducted an initial site visit in August 2024. During the site visit, top of the well casing was located in the underbrush approximately 45 ft from the lake shore within the Kintla Lake backcountry campground. The casing appeared to be roughly cut approximately 1 ft below grade and covered with stones. This matched the description by Boberg (1984). The interior of the casing was filled with wet dirt and debris. An attempt was made to remove the dirt from the casing. Approximately 1ft of the inside of the casing was exposed. The interior diameter of the casing measured approximately 10-inches. A small diameter (~1inch) pipe was observed along one side of the casing. It was unclear how far the pipe extends into the casing or what the purpose of the pipe is. Methane emissions were detected at low levels (< 4% LEL).

Services out of Cut Bank, Montana in the Summer of 2025 to begin planning the plugging and abandonment for late summer or early Fall 2026. This time frame would give the NPS time to complete the National Environmental Policy Act (NEPA) permitting and the contractor time to prepare equipment and coordinate mobilization to the well site. Liquid Gold modified a drill rig capable of meeting the project objectives so that it could be flown into the site by helicopter along with the associated cement pumping equipment. Additionally, Liquid Gold secured a landing craft that could be used to service the drilling operation via the campground road at the foot of the lake, which is approximately 7 miles from the well site. Because of the narrow road to the foot of the lake, the landing craft would also need to be air lifted in by helicopter. The use of the landing craft and a second smaller power boat significantly reduced the amount of helicopter support required for the project. However, because Kintla Lake is a designated nonmotorized lake, the use of these craft required waivers from the NPS and GNP.

Based on the site visit and the observed condition of the well, it was determined that the plugging and abandonment would require: · ·

·

· ·

Logistical coordination for remotely accessing the well since it is located in a roadless designated wilderness area. Cleaning out the casing and borehole either to total depth (1,450 ft) or to ~700 ft where gas was originally encountered. The clean out may require installing new well casing at the surface. Assessment of the depth and integrity of the casing once hole is cleaned out. If the casing extends to total depth, it would require perforation prior to cementing. If the hole is open (no casing), then no perforation would be required for the uncased interval. Following cleanout and casing assessment, cementing the well shut. Site regrading and restoration.

To minimize site disturbance at the well, raised platforms were constructed to stage equipment and the drill rig, and two Conex containers used for equipment storage relied on jack up legs rather than setting them directly on the ground. The field phase of the project kicked off in mid-July 2026 with an anticipated completion by the end of August 2026. On July 27, 2026, eleven loads of equipment, including the landing craft, drill rig and associated equipment were flown to the site using a Blackhawk helicopter. The landing craft and smaller motor boat were then used to transport equipment, fuel, and personnel to the site on a daily basis.

Following the site visit, Montana Tech solicited bids for the plugging and abandonment. As part of the bidding process, a site visit was required for any interested contractors prior to submitting a

2026 RMS AAPG

Once the drill rig and pumping equipment were assembled, the well head was excavated and a sump constructed around the well head. The top 3 ft of the 10 ¾-inch casing was cut and the well

63

BUTTE, MT

ABSTRACTS opened up. The well contained debris (mostly wood), which was removed and disposed of. Below the surface debris, the 10 ¾-inch casing extended down to 211 ft and below that, the well consisted of a 7 7/8-inch open hole to 1,379.85 ft. Based on observations of the well, the decision was made to plug the well from 1,354 ft without additional drilling.

STRATIGRAPHIC PATTERNS OF SILICICLASTICS WITHIN VISEAN MIXED CARBONATESILICICLASTIC STRATA, MISSION CANYON FORMATION, NORTHERN WILLISTON BASIN

The plugging required five cement plugs and one bentonite gel pill. The first plug was set from 1,354 ft to 1,292 ft. It consisted of 20 sacks of cement with 3% CaCl2 displaced with 5 barrels (bbl) of water. This was followed by a 9.2 lb bentonite gel from 970 ft to 850 ft, which was approximately 100 ft below the reported gas show. An intermediate plug was set from 850 ft to 777 ft using 30 sacks of cement with 3% CaCl2 displaced with 2.9 bbls of water. A third plug was attempted from 757 ft, however, due to significant cement loss to the formation, the interval was recemented using 30 sacks of cement with 3% CaCl2 and 0.75

This study focuses on the 50-75m thick interval within the middle portion of the Frobisher-KisbeyAlida interval of the Visean Mission Canyon Formation in the Northern Williston Basin. This interval was deposited during the onset of the (Visean) Late Paleozoic Ice Age (Montanez & Poulsen, 2013). The interval is a mixed carbonate – siliciclastic sequence which displays strong reciprocal sedimentation within a 3rd order composite sequence. Siliciclastic intervals herein are termed Kisbey sandstones and are the primary focus of the study. Kisbey siliciclastics consist of three distinct sand intervals termed K1 to K3, with the most well know and developed sandstone the K2, commonly referred to as “the Kisbey Sandstone” in literature and informal usage (Wittner, 1988; Harris et al., 1966). Kisbey sandstones can act as reservoirs, thief zones, compartments and as traps.

Presenter: Renaud, Carson (ROK Resources) Co-authors: John Lake (Lake Geological Services INC)

lbs cellophane per sack. This time, the plug was successful and brought up to 678 ft. The suspected gas zone was assumed to be successfully plugged by this effort. A casing shoe plug was set from 264 ft to 168 ft using 40 sacks of cement with 3% CaCl2. The surface plug was set from 50 ft to surface. Initially, 30 sacks of cement with 3% CaCl2 were pumped, however, 9 sacks of cement were lost through a hole in the casing at 31 ft. An additional 5 more sacks of cement were pumped and the cement drop slowed. The well was topped off with an additional 6 more sacks of cement, which stayed in place.

K1-K3 siliciclastics are associated with sea-level lowstands. Each sand typically has a basal exposure surface which shows karsting and incision. Subsequent siliciclastic deposition likely occurred during both down stepping and later sea level rise. Uppermost portions of K1-K3 siliciclastics have sheet-like geometries. Between K1-K3 siliciclastics are carbonate beds that are interpreted to have been deposited during transgression. This model is similar to the Permian age “lowstand bypass/transgressive preservation” model (Sonnenfeld & Cross, 1993; Kerans & Fitchen, 1995).

The casing was cut approximately 4 to 5 ft below the ground surface and a plate welded over the top. The sump was removed and the hole backfilled. The equipment was demobilized from the site on August 11, 20206 and the site recontoured. Because the work was completed from the raised platforms, limited site regrading was required.

Regionally K1-K3 siliciclastics are characteristically rusty-brown massive aeolian sandstones, or are millimeter to centimeter-scale wavy-crinkly supratidal algal laminated sandstone. Alternatively, Kisbey siliciclastics can appear as over-thickened sandstones on logs, and when mapped with the aid of 3D seismic display

Session: Orphan Well and Well Repurposing Room: Room 2 - Kelley/Seward Day/Time: Monday, October 26, 1:40 pm

2026 RMS AAPG

64

BUTTE, MT

ABSTRACTS environments, recording changes in drainage organization, sediment supply, and basin evolution. The Late Cretaceous Iron Springs Formation of southwestern Utah preserves a sand-rich fluvial succession deposited along the western margin of the Western Interior Seaway during Sevier orogenesis. Changes in channel stacking architecture and sediment composition within the formation provide an opportunity to evaluate how evolving source-to-sink transport relationships are recorded in foreland-basin fluvial strata.

distinct channel-form geometries. These sandstones incise underlying units and are locally up to 50m thick in the study area. In core these siliciclastics can display fully terrestrial sedimentary features including plant debris and typically lack calcite cements. Understanding Kisbey siliciclastic intervals is extremely important to oil finders, because interpreting the shelf stratigraphic patterns of these sediments can help define the edge of shorelines, where facies changes create stratigraphic traps. Also, these marker beds and corresponding exposure surfaces define sequence boundaries that are important for correlation and mapping. Lithological variations within incised channels systems led to compartmentalized fairways, altering migration pathways and creating unique traps. Fields that have been compartmentalized display irregular offset oilwater contacts as a result of incision and backfilling of channels.

This study integrates U–Pb detrital zircon geochronology and bulk-rock X-ray fluorescence (XRF) geochemistry from five stratigraphically distributed sandstone samples collected from Parowan Gap outcrops of the Iron Springs Formation. Detrital zircon age distributions were compared to potential source terranes, including the Cordilleran magmatic arc, Sevier fold-andthrust belt, and Mogollon Highlands using kernel density estimation (KDE), multidimensional scaling (MDS), and Kolmogorov–Smirnov (K–S) statistical analyses. Geochemical proxies derived from XRF data were used to evaluate changes in weathering intensity, redox conditions, and sediment composition through the measured section.

Several examples of these types of traps, along with a model of how to predict areas of reservoir preservation and destruction will be presented. The hope is that this model can be used predictively as a template for further exploration in low well density areas of North Dakota and Saskatchewan.

Results indicate stratigraphic shifts in both zircon age populations and geochemical signatures that coincide with observed changes in channel frequency and connectivity. Parowan Gap geochronology samples have a strong Sevier Fold and Thrust Belt source influence, with populations shifting up-section toward magmatic arc terranes to the southwest. A pronounced increase in chemical weathering indices near the top of the section suggests a reorganization of sediment transport pathways and/or increased transport distances within the fluvial system. These changes are interpreted to reflect evolving drainage connectivity and sediment delivery from the Sevier hinterland during orogenesis.

Session: Rocky Mountain Petroliferous Basins: Williston Basin Room: Room 1 - Big Butte/Highlands Day/Time: Monday, October 26, 9:25 am TRACING DRAINAGE REORGANIZATION DURING SEVIER OROGENESIS USING DETRITAL ZIRCON PROVENANCE AND XRF GEOCHEMISTRY Presenter: Robinson, Julie (Department of Geological Sciences, Brigham Young University) Co-authors: Samuel M. Hudson, Brooks B. Britt, Kevin Rey, Austin Toner, Charles Kewish, Brad Taylor, Sydney Crockett, Olivia Tatum (Department of Geological Sciences, Brigham Young University)

This integrated dataset demonstrates how combining provenance and geochemical approaches can help identify sediment-routing

Fluvial sediment routing systems link tectonically active, erosive source regions to depositional

2026 RMS AAPG

65

BUTTE, MT

ABSTRACTS cluster volume. This correlation indicates that final perforation geometry is not merely a geometric outcome of the erosion process but can serve as a physical indicator for controlling and interpreting fluid distribution at the cluster scale. Accordingly, a more balanced Perforation Geometry Uniformity Index corresponds to a more uniform distribution of injected volume among clusters and increases the likelihood of more effective cluster contribution. From a technoeconomic perspective, this chain of relationships suggests that selecting an optimized perforation diameter can improve stimulation efficiency by enhancing final geometric uniformity and increasing the uniformity of total cluster volume, thereby supporting higher cumulative production and, consequently, higher NPV. Therefore, the proposed framework transforms final perforation geometry from a purely geometric description into a quantitative, physical, and techno-economic criterion for evaluating cluster performance and optimizing perforation design in multicluster hydraulic fracturing.

changes within ancient fluvial successions and provides new insight into source-to-sink evolution during Late Cretaceous orogenesis in the Sevier foreland basin. Session: Geochronology and Provenance Room: Room 2 - Kelley/Seward Day/Time: Sunday, October 25, 4:25 pm PERFORATION GEOMETRY UNIFORMITY AS A PHYSICS-BASED INDICATOR OF CLUSTERLEVEL FLUID DISTRIBUTION IN MULTISTAGE HYDRAULIC FRACTURING Presenter: Saberi, Fatemeh (Department of Energy and Petroleum Engineering, University of North Dakota) Co-Authors: Hadi Jabbari (Department of Energy and Petroleum Engineering, University of North Dakota) This study presents a physics-based framework that uses the final, erosion-altered perforation geometry as a measurable proxy for cluster-level fluid distribution in multistage hydraulic fracturing. Within this framework, a coupled wellboreperforation-erosion model reconstructs the final perforation geometry of each cluster, from which the PGUI is derived from the variation of the eroded perforation cross-sectional area across clusters. The proposed index is considered a controlling metric for assessing the effect of perforation geometric evolution on cluster behavior, because final changes in perforation diameter, open area, and geometric growth can influence fluid distribution and the relative contribution of individual clusters. To evaluate this relationship, three perforation designs with initial diameters of 0.32, 0.60, and 0.75 in. were examined as case studies, and the Perforation Geometry Uniformity Index was compared with the Cluster Total Volume Uniformity Index. The results show that the 0.60-in. design, identified as the optimal case, provides more favorable geometric uniformity across the three stages compared with the smaller 0.32-in. and larger 0.75-in. designs, and this behavior is accompanied by improved uniformity in total

2026 RMS AAPG

Session: All Meeting Posters Room: Exhibit Hall - Copper Lounge PRELIMINARY EVIDENCE FOR BASEMENT STRUCTURAL INHERITANCE CONTROLS ON FRACTURE DEVELOPMENT AND HYDROCARBON MIGRATION IN THE NORTH PARK BASIN, COLORADO Presenter: Simoneau, Victoria I. (Colorado School of Mines) Co-authors: Stephen A. Sonnenberg (Colorado School of Mines) Inherited basement structures can exert a firstorder control on fault architecture, fracture development, fluid migration, and reservoir compartmentalization in Rocky Mountain petroleum basins. The Spring Creek Fault system of the North Park Basin, Colorado, is a basementrooted structure associated with structural compartmentalization, elevated fluid pressures, and significant hydrocarbon production. This ongoing study presents preliminary field observations evaluating whether inherited

66

BUTTE, MT

ABSTRACTS basement fabrics influence younger brittle deformation and, ultimately, fracture connectivity and hydrocarbon migration within the basin.

ASSESSING POTENTIAL CO2 STORAGE IN FRONTIER 2ND SAND AND MUDDY AT A WYOMING SITE BY ANALYZING VOLATILE SUBSURFACE FLUIDS IN UNPRESERVED WET CUTTINGS

Preliminary field investigations of basement exposures at Sheep Mountain and Delaney Butte have identified discrete structural domains characterized by dominant NW–SE-trending foliations, interpreted to represent the primary ductile basement fabric. These fabrics are locally overprinted by predominantly E–W-trending joint and fracture sets, with minor crenulation cleavage, indicating a later phase of deformation. Their orientation and overprinting relationships provide preliminary evidence that younger brittle structures developed during reactivation of the basement-rooted Spring Creek Fault system.

Presenter: Smith, Christopher (Advanced Hydrocarbon Stratigraphy) Co-authors: Charles Nye and Eugene Holubnyak (University of Wyoming), Michael Smith (Advanced Hydrocarbon Stratigraphy) In 2025, a well was drilled in Wyoming to assess a potential site for carbon capture and storage with the Frontier 2nd Sand (F2S) and Muddy being targets of interest. The injection scenario envisions 3 pads with 2 wells a pad with one well on each pad injecting CO2 into one formation or the other- 0.4 million metric tons (mmt) of CO2 would be injected a year for 40 years for 16 mmt total.

These initial observations suggest that inherited basement fabrics may influence the localization and geometry of subsequent brittle deformation and fracture development. Whether these relationships extend into the subsurface and influence fracture connectivity, permeability pathways, reservoir compartmentalization, and hydrocarbon migration remains under investigation. Ongoing work will define structuraldomain boundaries, constrain deformation timing using U–Pb geochronology, and integrate surface structural observations with 3D seismic interpretation, well logs, pressure data, and production data to test these relationships.

Session: All Meeting Posters

To assist in understanding the fluid distribution, composition, and history of the subsurface 58 wet cuttings samples collected on depth at 100 ft intervals, starting in the Baxter and ending in Morrison, were analyzed with rock volatiles stratigraphy (RVS). RVS can measure 40+ volatile subsurface fluids entrained in rock samples – data for the C4-10 hydrocarbons (HCs), CO2, and water were collected. RVS gently (no added heat/solvents) vacuum extracts, identifies, and quantifies volatiles via a novel cryo-trap mass spectrometry system. Unpreserved rock samples are crushed while under vacuum to open unexposed tight pores and fresh surfaces where volatiles still reside. Crushing also provides a measurement of mechanical strength. While sampling intervals were not ideal, observations about changes in absolute quantities and composition enable dentification of likely compartments–implying the presence of seals and sections of the subsurface out of communication with one another. Other features like HC migration pathways based on molecular signatures are observed. Lithology, density, and gamma ray data were also used.

Room: Exhibit Hall - Copper Lounge

Main observations were:

Although these results are preliminary, they establish a structural framework for testing links between basement inheritance, younger fault and fracture networks, and petroleum-system behavior in the North Park Basin. Continued integration of field and subsurface datasets will evaluate whether basement structural inheritance can improve predictions of structurally controlled fluid pathways and compartmentalization. If supported, these relationships may provide a transferable framework for evaluating basementinvolved petroleum systems elsewhere in the Rocky Mountain region.

2026 RMS AAPG

67

BUTTE, MT

ABSTRACTS CAPTURING STRANDED RESERVES IN THE PROLIFIC UINTA BASIN: LEVERAGING FAVORABLE GEOLOGY WITH 15,000-FT JSHAPED LATERALS

1) multiple compartments and potential seals in the Niobrara and Baxter, including one that has previously halted gas migration; 2) no evidence for large scale vertical HC migration through either formation; 3) possible compartmentalization separating the Muddy and F2S from adjacent formations; 4) strong HC migration signatures the F2S and the immediately overlying Frontier sample suggesting past vertical and/or lateral migration of HCs - likely a positive indicator suggesting minimal segregation within the injection zone and that the plume may readily spread laterally; 5) immediately above the deepest Frontier sample there are several hundred feet with no significant migration signatures while the shallowest sample in this zone has a signature indicating that the movement of gas was halted which correlates with notable lithology and mechanical strength changes – very promising evidence of an existing seal prevents the movement of gas;

Presenter: Smith, Kalen (FourPoint Energy) Co-authors: Jake Stuart (FourPoint Energy) Legacy development and surface-location constraints can leave prolific volumes of highly economic reserves inaccessible to conventional horizontal development. In the Uteland Butte and Wasatch Formations of the Uinta Basin, existing 5,000-ft horizontal wells prevented the full utilization of 10,000-ft lateral slots, leaving some of the best reserves in North America stranded. To overcome this geologic and engineering challenge, FourPoint Resources planned, permitted, and executed three 15K J-shaped horizontal wells in 2025 & 2026. These wells represent the first Jshaped horizontal wells drilled in the state of Utah and demonstrate a novel approach to accessing otherwise stranded reserves. The geologic architecture of the Uinta Basin is particularly conducive to complex horizontal wellbore geometries. Consistent structural dip and laterally continuous, relatively homogeneous target lithologies provide predictable reservoirs, while limited geologic hazards reduce uncertainty during extended wellbore execution. Combined with the high degree of stratigraphic repeatability observed across the basin, these characteristics provide a favorable environment for maintaining wellbore placement through complex threedimensional trajectories and extending reservoir access beyond conventional lateral configurations.

Significant HC liquids were noted by RVS in the Baxter, the lower Niobrara, the F2S, the Mowry, and the Morisson. While these and low water RVS measurements and/or indicators frequently matched notes of increased oil shows or flares, compositionally these HC liquids were not a viable resource – “dead oil”. Taken together these observations are very promising in terms of the site’s potential for CO2 storage with injection into the F2S and the Muddy without damaging a potentially viable oil resource.

A key technical challenge was maintaining the wellbore within the defined target zone while navigating the extended directional turn. Precise control of both azimuth turn radius and inclination was critical throughout the turn to follow formation structure and maintain reservoir contact. The 3 J-wells reached a total measured depth of approximately 18,000 ft (~15,000 ft completed) and successfully demonstrated the ability to execute three-dimensional wellbore

Session: Chemical Geology Room: Room 1 - Big Butte/Highlands Day/Time: Sunday, October 25, 3:35 pm

2026 RMS AAPG

68

BUTTE, MT

ABSTRACTS Formation. The discovery method was seismic and surface geology. The field has an areal extent of 9.6 square miles.

geometries across several target benches within the Uinta Basin. The three wells have demonstrated strong production performance, averaging approximately 60 Bbl/ft EUR’s, confirming the quality and economic potential of the previously stranded reserves. The 15,000-ft well design also provided a significant economic advantage, reducing DCF $/ft by up to 25% compared with a 10,000-ft development well. Additionally, the use of waterbased mud (WBM) reduced drilling costs by approximately $300,000 per well not including savings associated with fluid loss events. Beyond recovering reserves that otherwise would have been abandoned, these wells served as a feasibility test for future 20,000-ft U-shaped horizontal wells. The results demonstrate that extended, unconventional wellbore geometries can overcome surface and existing-well constraints while improving development economics and expanding access to prolific reserves in the Uinta Basin.

Loveland Field has produced 3.97 MMBO and 17.2 BCFG. Niobrara standalone production accounts for 43% of the total production. Niobrara and commingled zones account for 53% of the total production. Thus, to date the main reservoir target is the Niobrara. The Niobrara has low matrix permeability 0.01 md or less and low matrix porosity (3-10%). Vertical fractures are common in cores from the Niobrara. The Niobrara reservoir is considered to be a dual fracture-matrix porosity system. Fracturing is interpreted to be caused by the anticlinal structure and regional stress field system. The structure at Loveland field is Laramide in age. It is similar to other structures in the Front Range structure trend (e.g., Rabbit Mountain). The structure at basement level is interpreted to be bound by north and east-northeast trending faults. It is a relatively low relief structure on the moderately dipping (4 to 5 degrees) west flank of the Denver Basin. At the Niobrara and Codell levels, the structure could be described as a “box fold” or “pop-up structure.”

Session: Uinta Basin 1: Green River Formation Room: Room 1 - Big Butte/Highlands Day/Time: Sunday, October 25, 2:35 pm LOVELAND OIL FIELD, A LARAMIDE STRUCTURAL ANTICLINAL TRAP, DENVER BASIN, COLORADO

Session: Rocky Mountain Petroliferous Basins: Colorado Basins

Presenter: Sonnenberg, Stephen (Colorado School of Mines)

Day/Time: Monday, October 26, 11:00 am

Room: Room 1 - Big Butte/Highlands FROM OIL AND GAS TO CCUS: AN INTERACTIVE WEB APPLICATION FOR CARBON SEQUESTRATION AND SUBSURFACE ENERGY EXPLORATION

The Loveland oil field is located along the Front Range structural trend on the west flank of the Denver Basin. The oil field is a closed anticlinal structure and produces from the Lyons Sandstone, Dakota Sandstone, Muddy (J) Sandstone, Codell Sandstone, Niobrara Formation, and the Hygiene Sandstone. Many zones are commingled. The initial discovery was in the Hygiene Sandstone (1950), followed by the Dakota Sandstone (1955), Muddy Sandstone (1956), Niobrara Formation (1957), Lyons Sandstone (1961), and Codell Sandstone (1984). Recent horizontal drilling activity in the field is targeting the Codell Sandstone and Niobrara

2026 RMS AAPG

Presenter: St. Pierre, Gabriela A.E. (Utah Geological Survey) Co-authors: Michael D. Vanden Berg, Elliot Jagniecki and Ryan Gall (Utah Geological Survey) Utah has a wealth of subsurface geology suitable for oil and gas, EOR, and carbon storage exploration but data accessibility often limits exploration potential. To encourage and facilitate subsurface exploration across Utah, the Utah Geological Survey (UGS) has created the Carbon

69

BUTTE, MT

ABSTRACTS $12/t CO2, making them ideal candidates for geologic carbon storage. Other areas such as the northern Basin and Range Province do not have adequate data to evaluate carbon storage potential but remain of interest for future characterization.

Storage Portal, a web application designed to host published/unpublished subsurface analyses, subsurface datasets required for exploration, and relevant infrastructure layers. The Carbon Storage Portal includes a database of more than 40,500 wells from the Utah Division of Oil, Gas and Mining, geothermal wells and springs, and mineral exploration drillholes. A subset of the oil and gas wells database was modified to add LAS file availability and UGS vetted well top picks, allowing users to filter wells by specific formations (e.g., Mancos Shale). These layers were designed to be evergreen and will be updated at regular intervals as new wells are drilled and as new formation tops are interpreted. These data are complimentary to the cores and cuttings inventory layer, which displays all the available cores and cuttings available at the Utah Core Research Center. A new dataset compiled for this application is the rock properties dataset: a database composed of porosity, permeability, and formation water metrics. This dataset can be visualized and filtered by wells or formation and can be downloaded in a variety of formats. This compilation of subsurface data has dual value for both traditional exploration and emerging clean energy ventures.

Session: Orphan Well and Well Repurposing Room: Room 2 - Kelley/Seward Day/Time: Monday, October 26, 2:05 pm WESTERN POWDER RIVER BASIN NIOBRARA PERFORMANCE AND POTENTIAL: UPLIFT FROM MANAGED DRAWDOWN OPTIMIZATION, AND NIOBRARA "C" WINE-RACKING Presenter: Stout, Rex D. (Sage Butte Energy LLC.) Co-authors: Eric Roach (Sage Butte Energy LLC.) and Tanya Inks (IS Interpretation Services LLC.) The southwestern extent of the Central Basin Hotspot of the Powder River Basin (PRB) straddles the structural basin axis, where deep burial and regional heat flow combine to create a highly overpressured, high-maturity Niobrara–Mowry petroleum system. Sage Butte's Niobrara position is characterized by high pressure (0.74 psi/ft DFIT), high bottom-hole temperature (230°–250°F), and a volatile oil near its critical point. Recent Niobrara completions have utilized a managed pressure drawdown (MPD) strategy, yielding sustained oil rates and higher estimated ultimate recoveries (EURs) compared to offsetting aggressivedrawdown wells. Currently, seven Niobrara MPD horizontal wells — including the Aspen, Elm, Juniper, and Spruce developments — have outperformed 2024+ averages from the broader Powder River, Anadarko, Midland, and Williston basins on a 10,000-ft normalized cumulative oil basis.

Using the above subsurface datasets, the UGS characterized 15 unique geologic regions (or “georegions”) in Utah for carbon storage potential, utilizing unique subsurface workflows due to vast variations in data availability. For each highly ranked geo-region, detailed reservoir and caprock depth maps and isochores were made to highlight key carbon storage “plays”. Where possible, cost and storage capacity estimates of high-ranking geo-regions were calculated. Basins with the highest storage potential include the Paradox, Uinta, San Rafael Swell and Kaiparowits Basins, many of which have the possibility of combining CO2 storage with EOR. The Jurassic eolian sandstones of the Nugget-Navajo and Entrada reservoirs are the highest ranked storage play in the San Rafael Swell and Uinta Basin, with robust seals of the Carmel and Mancos Formations. These reservoirs have a P50 storage capacity of at least 5000 Mt of CO2 per year, at a cost of less than

2026 RMS AAPG

The high-pressure, high-temperature volatile fluids produced under traditional aggressive-drawdown flowback practices suggest a rapid drop in nearwellbore fluid pressure below bubble point, resulting in drastically reduced liquid mobility that suppresses liquid production rates and EURs. Additionally, aggressive-drawdown flowing surface pressures typically fall to 100–200 psi within 30–45

70

BUTTE, MT

ABSTRACTS spacing to 4–5 wells per drilling spacing unit (DSU), representing a 25–67% increase in Niobrara inventory. Together, MPD-driven performance gains and the emerging Niobrara C opportunity position the western PRB Niobrara as a resource base with both improved per-well recovery and materially expanded inventory — an underappreciated extension of the play within the basin's structurally deepest and most overpressured fairway.

days, requiring gas-lift assistance. Sage Butte Niobrara wells produced under MPD exhibit sustained elevated flowing pressures and liquid rates compared to their direct offsetting aggressive-drawdown counterparts, with the earliest MPD wells flowing naturally for 15 months — an unusually extended period. Sage Butte Niobrara EURs have increased to 62 Bo/ft versus 48 Bo/ft for previous aggressive-drawdown wells, and MPD is now standard practice for go-forward development. Productivity case studies against nearby offset operators confirm comparable reservoir quality, supporting continued development at existing spacing; MPD is increasing long-term unit recovery and inventory longevity.

Session: New Developments in Unconventionals Room: Room 1 - Big Butte/Highlands Day/Time: Sunday, October 25, 9:25 am QUANTIFYING ORDER IN FLUVIAL ARCHITECTURE: A SPATIAL STATISTICS APPROACH TO AUTOGENIC VS. ALLOGENIC CONTROLS ON CHANNELFORM ORGANIZATION

These drawdown-driven gains compound with a second, underexploited opportunity within the same stratigraphic package. Beyond the predominant western PRB Niobrara Marl target, this presentation highlights recent industry targeting of the lower Niobrara "C" — a TOC-rich (2–3%), basal member of the Niobrara petroleum system typically interpreted as a contourite (bottom-current) deposit with a marine erosional base. Regional mapping identifies 100+ existing Niobrara C producers basin-wide, with recent northwest Converse County wells confirming viability outside the historical Campbell County contourite depocenter. The Niobrara C averages 40–60 feet of gross thickness across the western extents of the Central Basin Hotspot, compared to over 100 feet within the contourite depocenter. Initial Niobrara C tests in the western PRB were short laterals completed with X-link fluids in marginally mature areas; recent wells are twomile laterals completed with modern designs and favorable maturity. Western Central Basin Hotspot case-study comparisons — based on a small but consistent early sample — show the Niobrara C outperforming the co-located Niobrara Marl by 45– 55% in normalized cumulative oil, with parallel gas uplift.

Presenter: Tatum, Olivia J. (Brigham Young University) Co-authors: Samuel M. Hudson, Barry R. Bickmore, and Emily J. Evans (Brigham Young University) Accurate geomodels of fluvial reservoirs depend on a thorough understanding of how channelforms are organized. The arrangement and distribution of fluvial architecture have long been used to interpret allogenic drivers such as tectonics, eustacy, and climate, but large-scale stratigraphic patterns are frequently overprinted by highfrequency autogenic patterns such as channel avulsion and reoccupation. Recent work demonstrates that autogenically driven systems can generate patterns nearly indistinguishable from those generated by allogenic drivers. Mischaracterizing controls on fluvial architecture produces models that poorly represent the distribution and connectivity of sandy channelforms, directly undermining subsurface prediction. To address this uncertainty, we present an integrated workflow that adapts and extends existing spatial statistics, applying them to highresolution photogrammetric outcrop models to quantitatively evaluate fluvial channelform

Incorporating the Niobrara C interval into existing development-unit inventory — layered with, or "wine-racked" alongside, the Marl — increases total identified locations from the current 3-well

2026 RMS AAPG

71

BUTTE, MT

ABSTRACTS an east-skewed asymmetric foreland basin. Field observations across 15 km of outcrop shows that sedimentation rates were very high during deposition of the Hawkesbury, and channelform size, geometry, and associated bedforms vary significantly both laterally and vertically across the outcrop belt. Chaotic, high energy fluvial deposits such as this can lead to complex architectural distribution that can be difficult to understand and predict in three-dimensional space. However, the Hawkesbury Sandstone shows large scale facies association patterns which are more predictable and organized than the smaller scale channelforms and geometries. Two distinct facies associations were identified in outcrop: Facies Association A (FAA) is more blocky, reddish in color, and coarser grained, whereas Facies Association B (FAB) is finer grained, lighter in color, and more finely and clearly bedded. Compositional differences obtained through outcrop pXRF characterization support this, with FAA showing increased Fe and Sr indicating increased diagenetic alteration when compared to FAB. The transitions between FAA and FAB are interpreted to be higher order surfaces that indicate the presence of compound architectural elements on the 10’s of meters scale in height and the kilometer scale in length. These compound architectural elements indicate changes on a system wide scale that are likely allogenic in nature, while smaller simple channelform elements are highly amalgamated and vary significantly in character, likely showing a dominance of autogenic processes. The identification of facies associations representing potential higher order elements allows for increased reservoir-scale predictability at this larger scale. This large-scale predictability is paramount for understanding the system and being able to extrapolate outcrop observations to subsurface interpretations in the Hawkesbury and analogous systems across the world.

organization. We applied this workflow to two Upper Cretaceous fluvial systems along the margin of the Western Interior Seaway: the Castlegate Sandstone of Utah, and the Ericson Sandstone of Wyoming. Both systems represent the maximum progradation of clastic wedges shed from the Sevier Orogenic Belt but occupy distinct positions within the foreland basin and display markedly different architectural characteristics, making them well suited for comparative analysis. Channelform distributions in both formations exhibit degrees of non-random organization across outcrop-scale transects. The Castlegate, a high net-to-gross, highly amalgamated system, shows only subtle deviation from complete spatial randomness, suggesting autogenic processes dominate channel organization with minimal detectable allogenic influence. The Ericson displays stronger non-random organization, with large channelform clusters regularly spaced ~100m apart, a pattern with direct implications for reservoir connectivity. Together, these results validate the sensitivity of the method across systems with different depositional characters. This workflow provides a reproducible, transferable framework for quantitatively characterizing fluvial channelform distributions at outcrop scale. Quantitative constraints on channel organization are essential inputs for geologically realistic geomodels, improving subsurface prediction and reducing uncertainty in reservoir characterization. Session: Sedimentology and Stratigraphy Room: Room 2 - Kelley/Seward Day/Time: Sunday, October 25, 2:10 pm FLUVIAL COMPOUND ARCHITECTURAL ELEMENT ORGANIZATION IN THE HIGH NET-TOGROSS HAWKESBURY SANDSTONE Presenter: Taylor, Brad (Brigham Young University)

Session: Sedimentology and Stratigraphy

Co-authors: Samuel Hudson, Julie Robinson, and Olivia Tatum (Brigham Young University)

Room: Room 2 – Kelley/Seward

The Triassic Hawkesbury Sandstone is a high energy fluvial system that was deposited in the Sydney Basin, which at the time of deposition was

2026 RMS AAPG

Day/Time: Sunday, October 25, 1:45 pm

72

BUTTE, MT

ABSTRACTS samples span ~36–55 kcal/mol. WRB oil-window entry occurs at ~108 and ~103 °C for the low- and high-hydrogen-index groups, respectively; modeled peak oil generation occurs at ~132 and ~158 °C. At geological heating rates of 1–2 °C/Ma, fraction-reacted models place much of the Mowry near peak oil generation, defined here as 0.50 fraction reacted, although modeled reaction progress varies substantially among organofacies.

BEYOND TMAX: REASSESSING MOWRY SHALE MATURITY THROUGH REGIONAL KINETIC MODELING Presenter: Toner, Austin D. (Brigham Young University) Co-authors: Samuel M. Hudson and Brad Taylor (Brigham Young University) The Mowry Shale is a prolific source rock, yet in southwestern Wyoming conventional thermal maturity models commonly classify it as immature. Tmax values of over 500 samples of outcrop, core, and cuttings are commonly classified as thermally immature (≤430 °C), despite regional oil and gas production that demonstrates mature hydrocarbons and effective expulsion. This study explores how organofacies variability and basin specific kinetic behavior can reconcile that discrepancy in the Greater Green River (GRB) and Wind River (WRB) basins and better constrain Mowry hydrocarbon-generation windows.

These results demonstrate that Tmax values alone ineffectively represent maturity and generative potential for the Mowry Shale in southwestern Wyoming. Hydrocarbon generation is heavily influenced by distribution of organofacies, which varies across the Greater Green River Basin according to depositional processes. Future work will expand kinetic sampling into other basins and incorporate kinetic parameters into basin models to improve predictions of the timing and extent of Mowry hydrocarbon generation and expulsion across Wyoming. Session: All Meeting Posters

More than 500 Mowry samples were screened by programmed pyrolysis, and representative lowand high-hydrogen-index samples were selected for kinetic analysis. Samples were Soxhletextracted with 89:11 chloroform–methanol to remove mobile kerogens and asphaltenes before open-system HAWK pyrolysis at heating rates of 1, 3, 10, 30, and 50 °C/min. Kinetics2015 modeling was used to determine activation energy distributions and model the fraction of kerogen reacted through geologic time and temperature.

Room: Exhibit Hall - Copper Lounge ORIGIN, RESERVOIR DEVELOPMENT AND INTRUSIVE IGNEOUS CONTROL OF A DEVONIAN CARBONATE HELIUM ACCUMULATION IN THE UTOPIA FIELD, NORTHERN MONTANA Presenter: Williams, Henry (Thor Resources Inc.) Thor Resources has been producing nitrogenhosted helium from Devonian Souris River Formation (Beaverhill Lake) carbonates and basal Cambrian (Flathead Formation) sands at the Knappen Field in south-east Alberta since 2019, with over 7.5 BCF raw gas and 100 MMCF helium produced to date. Thor also has two exploration discoveries currently undergoing appraisal and development planning in SE Alberta and one at Utopia in Liberty County, northern Montana, plus land holdings with drill-ready locations on other seismically defined structures.

The results show below average activation energies and basin specific variation in kerogen composition and reaction progress. GRB samples retain similar activation energy distributions across hydrogen-index groups, dominated by an algal organic matter population at ~50–55 kcal/mol and a secondary terrestrial population at ~60–65 kcal/mol. Modeled oil-window entry occurs at ~102 °C for low-hydrogen-index samples and ~122 °C for high-hydrogen-index samples. WRB distributions vary more strongly with hydrogen index: low-hydrogen-index samples center near 50 kcal/mol with a minor ~60 kcal/mol population, whereas high-hydrogen-index

2026 RMS AAPG

The Utopia Field, located on a 5 square-mile anticlinal structure, was first discovered by Texaco in 1944 following 2D seismic acquisition and the drilling of Laas 1 which encountered methane in

73

BUTTE, MT

ABSTRACTS Session: Helium and Hydrogen

the Mississippian Madison Formation. Laas 2 drilled in 1946 was completed in the Devonian Nisku Formation and flowed 4.35 MMCF/D, but the gas was found to be non-flammable with 78.8% N2 and 0.87% He and it was subsequently converted to a Madison producer.

Room: Room 2 - Kelley/Seward Day/Time: Monday, October 26, 9:25 am THE PORTABLE ED-XRF EXPERIENCE: CONSISTENCY, ACCURACY, AND THE WORLD OF MAKE BELIEVE

In 2021 Thor deepened a standing wellbore Laas 22-14 drilled by True Energy in 2012 to test the helium potential of the Nisku, Souris River and Flathead formations. A porous, gas-filled Nisku dolomite reservoir with 25% porosity and good helium gas response, equivalent to that found in Laas 2, tested 4.2 MMCF/D raw gas with 0.86% He. Deeper in the well a 60m igneous intrusion was encountered within the lower Cambrian shale and carbonate sequence deposited above crystalline Precambrian basement. Plans for appraisal drilling and production of the Nisku reservoir are currently in progress.

Presenter: Wright, Milly (Rohmtek) Co-authors: Harry Rowe, Austin Morrell, and Michael Nieto (Rohmtek) The portability and user-friendly design of modern energy-dispersive X-ray fluorescence (ED-XRF) instrumentation often create an impression of analytical simplicity. However, without careful consideration of sample preparation, spectral complexity and calibration strategy, this perception may lead to overconfidence in reported results. In particular, insufficient attention to raw energy spectra and elemental peak interferences can result in significant inaccuracies in compositional interpretation. The purpose of this presentation is to educate generators and users of ED-XRF data on the complexity of elemental analysis, focusing on the challenges associated with quantifying chalcophile elements—such as Zn, As, Pb, Se, Ag, Hg, Sn, Sb, Bi, and Tl—in a relatively simple serpentinite matrix. These elements frequently occur together, and their characteristic X-ray emission lines often partially or fully overlap (e.g., Zn–Hg, As–Pb, Se–Tl), producing complex spectra that complicate deconvolution and verification of quantitative results. Additional uncertainty arises from the limited availability of matrix- and compositionmatched reference materials for calibration. In many applied settings, fundamental parameter (FP) calibrations are employed for convenience; however, these approaches may not adequately account for matrix effects in heterogeneous geologic samples, potentially compromising data reliability. The performance of FP-based approaches (common to all modern ED-XRF instrument systems) is evaluated in the context of gravimetrically-defined chalcophile-bearing serpentinite. In addition, an empirical strategy for resolving spectral overlaps and improving

Thor’s Utopia Vibroseis 3D survey, completed in 2022 and designed to determine the closure area, origin and height of the structure, also clearly imaged the intrusion encountered in Laas 22-14. This indicated a concordant laccolith forming the core of the domal structure. Based on outcrops of igneous intrusive and extrusive complexes elsewhere in central Montana this is mostly likely early Eocene in age. Seismic interpretation and petrographic analysis have confirmed the nature and composition of the intrusion and its role in the origin of the field. Cores from Nisku producing hydrocarbon wells in the East Kevin Field, Toole County some 20 miles NE of Utopia which have similar reservoir wireline log response were studied. These include bedded dolowackestone intervals reaching 25% porosity and 900mD core permeability within otherwise tight anhydritic carbonates. Most are from an interval equivalent to that at Utopia, suggesting a regional, depositionally-controlled origin. Initial reservoir porosity development is believed to have formed during early, shallow burial dolomitization but this was subsequently modified during deeper burial dolomitization demonstrated by vuggy porosity and coarse euhedral dolomite crystallization.

2026 RMS AAPG

74

BUTTE, MT

ABSTRACTS Building on the work of Zumberge et al., 2024, this presentation will provide a high-level overview of key geochemical learnings pertinent to the Uinta and other central Cordilleran foreland basins. After providing a detailed explanation of the TruSat© analytical workflow, it will relate the outputs back to industry recognized formation evaluation concepts typically applied to geophysical logs. By integrating aspects of these laboratory rock based geochemical & petrophysical outputs with corresponding formation evaluation workflows, it is possible to quantify differences in movable and bound fluid fractions within petrophysical workflows, accounting for holistic complexities in the matrix and fluid systems.

analytical confidence, including optimized calibration workflows, spectral inspection protocols, and validation against independent analytical methods will be discussed. Session: Chemical Geology Room: Room 1 - Big Butte/Highlands Day/Time: Sunday, October 25, 4:25 pm UTILIZATION AND PRACTICAL APPLICATION OF ROCK BASED MEASUREMENTS IN FORMATION EVALUATION OF STANDARD GEOPHYSICAL LOGS IN A COMPLEX FLUID/ROCK SYSTEM. Presenter: Yokoyama, Christopher (GeoMark Research) Co-authors: Alex Zumberge and Nathan Piper (GeoMark Research)

Session: Exploration Methods Room: Room 1 - Big Butte/Highlands

The geological history of the Uinta Basin provides a unique suite of challenges and opportunities for ongoing hydrocarbon appraisal, development, and exploitation. One of the biggest challenges is the quantification of in situ reservoir fluid volumes and the determination of which fluid fractions are more likely to enter the production stream. Historically, the focus of formation evaluation was geological in nature (i.e. the matrix-pore wall boundary), with the composition of fluids residing in said pores either greatly simplified or included as an engineering afterthought to the initial model. For decades, GeoMark Research has long been considered an industry leader in Geochemical analysis of hydrocarbon reservoir fluids. A lesserknown capability of the laboratory is the quantification of pore fluid volumes and measurements typically considered in the petrophysical domain via their TruSat© workflow & product line(s). This workflow offers a novel rockbased approach for quantifying total storage capacity in unconventional and hybrid reservoirs. Through various proprietary client projects and two phases of industry consortia, this workflow has been applied extensively across North America’s unconventional plays, aiding various operators in the identification of sweet-spots and play-fairway high grading.

2026 RMS AAPG

Day/Time: Monday, October 26, 3:55 pm

75

BUTTE, MT

SPEAKER INDEX

SPEAKER INDEX SPEAKER

DAY

Akyol, C.

Both

Beaucamp, C.

Mon

Birdwell, J.

LOCATION

SESSION

Exhibit Hall - Copper Lounge

All Meeting Posters

3:30 pm

Room 2 - Kelley/Seward

Montana Energy Resources and Geology

Sun

8:35 am

Room 2 - Kelley/Seward

Geothermal Resources

Birdwell, J.

Sun

1:45 pm

Room 2 - Kelley/Seward

Sedimentology and Stratigraphy

Birdwell, J.

Mon

8:35 am

Room 2 - Kelley/Seward

Helium and Hydrogen

Brennan, D.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

Brinkerhoff, R.

Sun

1:45 pm

Room 1 - Big Butte/Highlands

Uinta Basin 1: Green River Formation

Brinkerhoff, R.

Mon

1:15 pm

Room 1 - Big Butte/Highlands

Uinta Basin 2: Green River and Paradox Resources

Burton, Z.

Mon

10:35 am

Room 2 - Kelley/Seward

Subsurface Utilization

Buursink, M.

Mon

11:00 am

Room 2 - Kelley/Seward

Subsurface Utilization

Caldwell, M.

Mon

3:55 pm

Room 2 - Kelley/Seward

Montana Energy Resources and Geology

Charoensuk, J.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

Davison, R.

Sun

9:00 am

Room 2 - Kelley/Seward

Geothermal Resources

Day, T.

Sun

2:10 pm

Room 1 - Big Butte/Highlands

Uinta Basin 1: Green River Formation

Ellsworth, P.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters (with core)

Fields, K.

Sun

Room 2 - Kelley/Seward

Critical Minerals

Fullwood, A.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

Gall, R.

Sun

11:00 am

Room 2 - Kelley/Seward

Critical Minerals

Gianoutsos, N.

Mon

1:15 pm

Room 2 - Kelley/Seward

Orphan Well and Well Repurposing

Gourari, D.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

2026 RMS AAPG

TIME

10:35 am

76

BUTTE, MT

SPEAKER INDEX SPEAKER

DAY

TIME

LOCATION

SESSION

Greenhalgh, B.

Sun

10:35 am

Room 1 - Big Butte/Highlands

Rocky Mountain Petroliferous Basins: Mowry Shale

Halpern, H.

Sun

8:35 am

Room 1 - Big Butte/Highlands

New Developments in Unconventionals

Hendrix, M.

Mon

10:35 am

Room 1 - Big Butte/Highlands

Rocky Mountain Petroliferous Basins: Colorado Basins

Hennes, A.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters (with core)

Hicks, K.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

Hofmann, M.

Mon

8:35 am

Room 1 - Big Butte/Highlands

Rocky Mountain Petroliferous Basins: Williston Basin

Hofmann, M.

Sun

3:35 pm

Room 2 - Kelley/Seward

Geochronology and Provenance

Holzer, R.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

Hudson, S.

Sun

Room 1 - Big Butte/Highlands

Rocky Mountain Petroliferous Basins: Mowry Shale

Hughes, G.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

Inks, T.

Mon

3:05 pm

Room 1 - Big Butte/Highlands

Exploration Methods

Johnson, M.

Sun

11:25 am

Room 1 - Big Butte/Highlands

Rocky Mountain Petroliferous Basins: Mowry Shale

Kewish, C.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

LaGesse, J.

Mon

11:25 am

Room 2 - Kelley/Seward

Subsurface Utilization

Lobreau, D.

Mon

9:00 am

Room 2 - Kelley/Seward

Helium and Hydrogen

Matheny, J.

Mon

1:40 pm

Room 1 - Big Butte/Highlands

Uinta Basin 2: Green River and Paradox Resources

Matheny, J.

Mon

2:05 pm

Room 1 - Big Butte/Highlands

Uinta Basin 2: Green River and Paradox Resources

McDowell, B.

Mon

11:00 am

Room 1 - Big Butte/Highlands

Rocky Mountain Petroliferous Basins: Colorado Basins

Moll, J.

Sun

4:00 pm

Room 2 - Kelley/Seward

Geochronology and Provenance

2026 RMS AAPG

11:00 am

77

BUTTE, MT

SPEAKER INDEX SPEAKER

DAY

TIME

LOCATION

SESSION

Moore, K.

Mon

3:05 pm

Room 2 - Kelley/Seward

Montana Energy Resources and Geology

Moreland, T.

Mon

3:30 pm

Room 1 - Big Butte/Highlands

Exploration Methods

Nell, M.

Sun

2:35 pm

Room 2 - Kelley/Seward

Sedimentology and Stratigraphy

Nesheim, T.

Mon

9:00 am

Room 1 - Big Butte/Highlands

Rocky Mountain Petroliferous Basins: Williston Basin

Parker, S.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

Pepin, J.

Sun

9:25 am

Room 2 - Kelley/Seward

Geothermal Resources

Ramirez, K.

Sun

9:00 am

Room 1 - Big Butte/Highlands

New Developments in Unconventionals

Ramirez, V.

Sun

11:25 am

Room 2 - Kelley/Seward

Critical Minerals

Reichhardt, D.

Mon

1:40 pm

Room 2 - Kelley/Seward

Orphan Well and Well Repurposing

Renaud, C.

Mon

9:25 am

Room 1 - Big Butte/Highlands

Rocky Mountain Petroliferous Basins: Williston Basin

Robinson, J.

Sun

4:25 pm

Room 2 - Kelley/Seward

Geochronology and Provenance

Saberi, F.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

Simoneau, V.

Both

Exhibit Hall - Copper Lounge

All Meeting Posters

Smith, C.

Sun

3:35 pm

Room 1 - Big Butte/Highlands

Chemical Geology

Smith, K.

Sun

2:35 pm

Room 1 - Big Butte/Highlands

Uinta Basin 1: Green River Formation

Sonnenberg, S.

Mon

11:00 am

Room 1 - Big Butte/Highlands

Rocky Mountain Petroliferous Basins: Colorado Basins

St. Pierre, G.

Mon

2:05 pm

Room 2 - Kelley/Seward

Orphan Well and Well Repurposing

Stout, R.

Sun

9:25 am

Room 1 - Big Butte/Highlands

New Developments in Unconventionals

Tatum, O.

Sun

2:10 pm

Room 2 - Kelley/Seward

Sedimentology and Stratigraphy

Taylor, B.

Sun

4:00 pm

Room 1 - Big Butte/Highlands

Chemical Geology

2026 RMS AAPG

78

BUTTE, MT

SPEAKER INDEX SPEAKER

DAY

Toner, A.

Both

Williams, H.

Mon

Wright, M. Yokoyama, C.

2026 RMS AAPG

TIME

LOCATION

SESSION

Exhibit Hall - Copper Lounge

All Meeting Posters

9:25 am

Room 2 - Kelley/Seward

Helium and Hydrogen

Sun

4:25 pm

Room 1 - Big Butte/Highlands

Chemical Geology

Mon

3:55 pm

Room 1 - Big Butte/Highlands

Exploration Methods

79

BUTTE, MT

SEE YOU NEXT YEAR! 2027 AAPG ROCKY MOUNTAIN SECTION ANNUAL MEETING STAY TUNED FOR MORE DETAILS

aapgrms.org AAPG Rocky Mountain Section Denver Earth Resources Library C/O RMAG 730 17th St, B1 Denver, CO 80202