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AirandGasDrillingManual AirandGasDrillingManual ApplicationsforOil,Gas,GeothermalFluidRecovery Wells,SpecializedConstructionBoreholes,andthe HistoryandAdventoftheDirectionalDTH
FourthEdition
WilliamC.Lyons JamesH.Stanley
FranciscoJ.Sinisterra
TomWeller
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Preface Thisisthe fourthedition ofthe AirandGasDrillingManual.The firstedition of thisbookwaspublishedin1984bytheformerGulfPublishingCompanyof Houston,Texas.Thatinitialeditionwaswrittenprimarilyfortheoilandgas recoverydrillingindustry.This firstedition enjoyedmoderatesuccessand wassoldoutofitsinitialprintingbythelate1980s.Althoughitwasnotknown atthetime,thesuccessofthisfirstbookanditscontentinthelaterpartofthe 1980sandearly1990s,wasinreality,ananomalysincethoseyearsweresome oftheworsteverexperienceduptotimebythepetroleumindustryintheUnited States.Intheearly1990s,theNorthAmericanpetroleumengineersandtheir uniqueinnovativedrillingpersonnelhadbeguntoconsiderthepotentialadvantagesofdrillingandcompletingwellswithdrillingfluidpressureslowerthanformationporepressures.Thebirthof underbalanced drillingandcompletion techniqueswasunderway.Ataboutthissametime,thebook’sauthorsbegan consideringanew secondedition ofthebook.
Inthelate1990sGulfPublishingCompanybeganconcentratingonitsinternationalenergyinformationbusinesses,e.g., WorldOil, PetroleumEconomist, and HydrocarbonProcessing,andbeganlosinginterestitslonglistofprofessionalbooktitles,e.g., AirandGasDrillingManual.Thisledtheauthorstoseek anewpublisherfora secondedition.Aftergettingareleaseofthebooktitlefrom thenewownersofGulfPublishingCompany,theauthorsbegansearchingfora newpublishingcompany.Theauthorsenvisionedthenew secondedition would initiateinvestigationsintounderbalanceddrillingandcompletionsengineering planningandoperations.Also,thisneweditionwouldexpanditsindustrialoutlooktoincludegeothermaldrillingandcompletions,andanearlylookintodeep constructionoperationsutilizingdirectcirculationandreversecirculationair hammertechnologies.This secondedition waspublished2001undera McGraw-HillCompanyprofessionaltitle.
Duringthe2000s,technologiesforbothdirectcirculationandreversecirculationofairandgasdrillingequipmentandoperationshadgreatlyimprovedin theinterveningyears.ThiswasparticularlythecaseintheAppalachianregion wherepioneerslikeBrooksJavins,RubenGraham,RudyLyon,AngeloSpedale, RinerBeccu,TomDonovan,GlennWright,JayGodfrey,RayShelor,RudyFlores, JeffWhite,ShantanuSwadi,TomWeller,andmanyotherswhopushedthe designsoftheDTHandtheirapplications.Thiswasparticularlythesituation withthenewdiscoveriesofproducibleoilandgasfromhorizontallydrilled andfrackedwellsintheUticaandMarcellusshales.TheseAppalachiandiscoveriespromptedinterestbylocaldrillingequipmentsuppliersandcontractorsto improvetheverticaldrillingtimesandcostefficiencybyincorporatingdownhole airhammers(DTHs)intheBHAs.Alongwiththoseadvanceswerethemany
greatstridesforwardinreversecirculationdrillingequipmentformining,environmental,constructionapplicationsbyArtHolteandhisteaminOregon,and internationalmanufacturesspecializinginthistypeoflargediametershallow depthdrillingequipment.Throughthe2000s,Elsevierhadacquiredaccessfor rightstopublishprofessionalbooksfromtheoldGulfPublishingCompany. Thenew thirdedition ofthe AirandGasDrillingManual waspublishedby Elsevierin2009.
Thenew fourthedition haspulledtogetherthenewestinnovationsforboth thedirectcirculationandthereversecirculationtechnologiesoverthatpast decade,andcondensedtheimportantengineeringcalculationsandapplications forbothoftheseimportantdrillingtechnologies.Themajorinnovationindirect circulationhasbeenthedevelopmentoftheabilitytodrilllongreachand mediumreachdirectionaldrillingwithBHAscomposedofPDMsrotatingDTHs. InreversecirculationArtHolteandhisteaminOregondevelopedtheabilityto drilllargediameterboreholesandgroutthemasthedrillingequipmentiswithdrawnfromtheborehole.Thesearespectacularinventionsfortheindustries theyserve.This fourthedition,asinthe thirdedition,makesuseoftheMathcad mathematicalmodeling.Theseexamplesolutionsshowstep-by-stepcalculations infamiliarmathematicsthatcanbeduplicatedinanyoftheengineeringprogramminglanguages,FORTRAN,C+,MatLab,etc.Mathcadisanimportanttool forteachingengineersandtechniciansthelogicorderlysolutionsandthevalue ofthecalculationsforplanning.
TheauthorswouldliketothankthestaffatElsevierfortheirforbearanceand greatpatienceduringthecreationofthisnewfourthedition.WewouldparticularlyliketothankKatieHammon,theElsevierAcquisitionsEditorwhotook anotherchanceonustoproducea fourthedition onthissubject.Wewouldalso liketothankourEditorialProjectManagersHillaryCarrandMonaZahirfor strugglingthroughourdelays.Thereallyvaluableassistancecamefromour figuredrawingartistsandtheproofreadersthathadtoenduremanydrafts. OurspecialthanksgoouttotheartistsTrishRichardsonandAnnGardner whogaveusnearinstantreproductionsfromourhandsketches.Theproof readersenduredaspecialmessofmissing(to’s,the’s,in’s,a’s)astheydealtwith ourlatenightdraftsbytheauthors.Soourthanksgoouttoourproofreaders, GlennaWoody,GracePeterson,andAnnGardnerwhohadtodealwithnearly threeyearsofendlessrevisions.
Acknowledgments “Iwouldliketothankthefollowingpeopleforsharingtheirexpertise:ArtHolte, FrankA.Seidel,ReubenL.Graham,BoyunGuo,RudyFlores,PatSullivan,and ShaneSayler.”
Introduction,Calculation Programming,and UnitSystems 1 1.1 INTRODUCTION Thereisawidevarietyofairandgasdrillingoperationsbeingusedbymany diverseindustriesinagreatvariationoflocationsaroundtheworld.Thesevary fromtheair-orgas-assisteddrillingofveryshallowsubsurfaceboreholesfor largeandsmallconstructionprojectstothedrillingofextremelydeepvertical tohorizontalboreholesusedfortheextractionofimportantnaturalresources (e.g.,freshwaterresources,geothermalfluidswithdissolvedmineralsinlive steam,naturalgas,andcrudeoils).Bothindustryandgovernmententitiessponsortheseoperations.Fromtheinceptionoftherockandsoildrillingtechnologies forperceivedneedsinindustries,theindividualinventorswithinthesemarkets havebeendedicatedtoinnovationsthatwouldmakethesedrillingoperations safer,reliable,andcost-effective.Suchinnovationsarefollowedbyactivedevelopmentofnearlyallnewideasandultimatelythecommercialapplicationwithin thevariousindustries.
Deepholedrillingairandgastechnologiesusedfordiscoveryandrecoveryof crudeoil,naturalgas,andgeothermalfluidshaveinthepastbeenlimitedtouse inmaturesedimentarybasins.Maturesedimentarybasinsareolderbasinsthat havecompetentsubsurfacerockformations,arewellcementedwithnaturalminerals,andhavebeentectonicallyupliftedsuchthatlittleformationwaterremains innear-surfaceporousandfracturedbeds.Usually,theirgeologicalagesare priortoabout65millionyears.ModernairandgasdrillingtechnologyandoperationsbeganintheUnitedStatesinthe1930s.Itispresentlybeingusedinmany drillingoperationsthroughouttheworld’smanyoilandgasproducinggeologic provinces.Itisimportantatthistimeinthedevelopmentofthistechnologythat thebasicprinciplesofthetechnologybecommunicatedinamannerthatalldrillingpersonnelwillunderstand.
Innovationinsubsurfacedrillingequipmenthasbeenusuallyinitiatedby smallerbusinessentitiesorindividualinventors.Theseinnovatorsarethe “tinkers” intheindustryandtheideasforchangesoftencomefromthefieldhands whooperateandhandlethesetoolsonaday-to-daybasis.Therearemanyexamplesoftheseinnovationscomingfromtheseinnovativesmallbusinessentities overthepastsevendecades.Examplesofsuchimportantearlyinnovationare asfollows:thetopdriverotarysystem,thedownholecompasssub,thebent
AirandGasDrillingManual. https://doi.org/10.1016/B978-0-12-815792-3.00001-5 # 2021ElsevierInc.Allrightsreserved.
sub,fordirectiondrilling,theformationcoringbit,thedownholepositivedisplacementmotor(PDM),thedownholeairhammer,andthereversecirculation drillstring.Therefore,thismanualwilldiscussnotonlytheexistingimportant technologiesbutalsosomeofthenewinnovationsthatareenteringthevarious industrymarkets.Itisbelievedthatthiskindofexposuretothenewinnovations takingplaceinindustrywillhastentheacceptanceandapplicationofthese inventionsintothelargerindustrialmarkets.Inessence,thelargermarketswill become “infected” earlierfromthesuccessesinthesmallermarkets.
Largerdiametershallowandintermediatedepthwellsareoftendrilledwith reversecirculationtechniques.Thesetechniquesandtheirassociatedequipment areeasiertomanufacturetoincorporateanynewinnovationsandtestthem. Thus,virtuallyunknownideas,likereversecirculationdrilling,maysomeday beusedindeepwelldrillingwithsmalldiameterdrillstringBHAs.Thatwill likelynecessitatetheinventionofnewmaterialsandfabricationtechniquesthat havenotyetbeeninventedtocreatetheconceptofflexibledualwallpipes.
Airandgasdrillingtechnologiesaccountforapproximately10%ofthe world’slandoilandgasdrillingoperations.Itwasasomewhathigherpercentage adecadeorsoago,butoverthatdecade,theoilandgasdrillingindustrywasina recessionanddrillingoperationsarealwaysthefirstbudgetitemtobecutbackin slowmarkettimes.Withthosecutbackscomesaslowdownininnovationsin existingtechnologiesandtheirassociatedoperations.
However,shallowdrillingoperationsforlargediameterconstructionholes, pipelinedirectionaldrillingofnearhorizontalboreholes,andcablelying(not countingaugerborings)utilizecloseto50%airdrillingtechnologieswithcompressorpressurizedairflowforremovingdrillbitcuttings.
Thismanualshowstheengineerorengineeringtechnicianhowtousethe includedequationsineachchaptertocreatecalculationprogramsthatcanbe usedtopredicttheair(orgas)pressuresatspecificpositionsinsidethedrillstring andintheannulusaroundthedrillstringintheflowloop.Thiswillgiveanaccurateestimateoftheinjectionpressurerequiredfromtheselectedcompressor package.Foradirectcirculationoperation,theloopcalculationsequencemust beinitiatedwiththeonlyknownpressureintheloop.Thatistheexitpressureat theexitendoftheblooeylinewiththeentraineddrillbitcuttings(andany injectedorformationliquids)beingliftedfromthebottomoftheborehole.If theoperationisusinga “solid-gasbuster” oradevicetoseparatethesolidsor dustfromthereturnflowfromthebottomoftheborehole,thentheknownpressurewillbeattheexitofthegasfromthesolid-gasseparator.Forareversecirculationoperationusingadual-walleddrillstring,theinitiatingpressurewillbe attheexitfromtheblooeylinethatisconnectedtothetopoftheinsidepipeflow spaceofthedualwalldrillpipe.Thecalculationwillproceedinreverse,down flowspaceoftheinsidepipe,throughthedrillbitnozzlesanduptheannulus spaceinthedualwalldrillpipetothecompressorinjectionpressure.Hereagain, ifasolid-gasseparatorisbeingused,theinitiationpressureattheseparatorexit willbeused,whichisalsoatmospheric.
1.2 CALCULATIONPROGRAMMING Engineersanddrillingsupervisorypersonnelneedtomakepredictivecalculationsinordertomaketheirdrillingoperationsefficientandcost-effective.The predictioncalculationsforairandgasdrillingtechnologyarecomplicatedand willrequirethecreationofcalculationcomputerprograms.Therearesophisticatedairandgasprogramsavailablecommercially.Butinthetraditionofmost engineeringfields,oncethebasicoutlineoftheprogramhasbeenoutlined,we tendtohandthe “careandfeeding” oftheprogramovertothecomputerscience department.TheauthorshavechosentouseMathCadasourprimarytooltocommunicatetothereadersthedetailsofhowairandgasdrillingpredictivecalculationsaremade.TheseMathCadsolutionsareverytransparentandarewritten inasequencethatanengineerorengineeringtechnicianwoulddoiftheywereto dothecalculationbyhand.Intheevent,theconsultancyorcompanyrequiresthe useofengineeringprogramminglanguageslikeFORTRAN,MATLAB,Pascal, Basic,VisualBasic,Java,C,andC++.Thereadercaneasilycopyoursequence intotheotherprogramminglanguages.
ThedetailedMathCadsolutionsaregivenintheappendicesandtheresultsare summarizedfromthosecalculationsineachassociatedchaptertext,table,andfigure.ThesolutionsarepresentedinbothUSCSunitsandSIunits.Itisassumedthat newcomerstothistechnologywilleventuallymakethechoiceofwhethertousean existingcommercialprogramortodeveloptheirowncompanyinternalprogram.
1.3 TERMINOLOGY Theobjectiveofthisprofessionaltextistofamiliarizethereaderswiththebasic terminologyandoperationalapplicationsofthisnewfieldofairandgasdrilling technology.Theuseofthistechnologyislimitedtolanddrillingoperations. Therearethreesubcategoriesofthistechnology:(1)airandgasfluidsdrilling, (2)aeratedfluidsdrilling,and(3)stablefoamfluidsdrilling.Thistechnology isutilizedbyindustrytofulfilltwospecificdrillingobjectives.
Performancedrilling :Thistypeofdrillingtakesadvantageofthelowannulusbottomholepressuresthataccompanytheuseofthistechnology.Lowannulusbottomholepressuresusuallyresultinhigherratesofpenetrations.Thistype ofdrillingoperationisappliedintheupperportionsofawellboreabovethe potentialproducingreservoirformation.Thespecificobjectiveofthistypeof drillingistodrillmorerapidlythroughtheupperformationsabovethereservoir andtoultimatelyreducethecostofadrillingoperation.
Underbalanceddrilling :Hereagain,thistypeofdrillingagaintakesadvantageofthelowannulusbottomholepressurecharacteristicofthetechnology. Underbalanceddrillingusesvariousbottomholepressurecapabilitiesofair andgas,andaeratedandstablefoamdrillingfluidstodrillintopotential
producingreservoirrockformationswithannulusbottomholepressureslower thanthestaticreservoirpressure.Inthismanner,thereservoirfluidsflowtothe wellboreasthedrillbitisadvancedthroughthereservoir.Underbalanceddrillingoperationsattempttoavoiddamagetothereservoirrockformationsothat thereservoirwillproduceeffectivelythroughitslife.
1.4 UNITSYSTEMS Modernengineeringpracticescanbetracedbacktotheearly8thcenturyADwith thetraditionofthe “masterbuilder.” ThiswasthetimeofthecreationofthemeasureknownastheCharlemagnefoot.Fromthe8thcenturyintothe17thcentury, avarietyofweightsandmeasureswereusedthroughouttheworld.Itwasnot untiltheWeightsandMeasuresActof1824thatacompleteBritishImperialSystem(BIS)wascodifiedwithintheBritishIsles,BritishCommonwealthcountries, andinsomeoftheformercoloniesoftheBritish.TheUnitedStates(US)actually didnotacceptthefullBritishImperialSystem.TheUnitedStatesmadeuseof someofthemajorunitswithinthesystemandsomeoftheolderunitsthat hadevolvedthroughtheyearsofcolonialismbefore1824.Thisevolutionof usagewithintheUnitedStatesultimatelybecametheUnitedStatesCustomary System(USCS)unitsthatisstillincommonusetoday.
Thedevelopmentofsomeofthebasicunitsthatultimatelybecamepartofthe present-daySystemInternationald’Unitesprobablybeganaroundthetimeof LouisXIVofFrance.ThissystemisknowntodayassimplySIunits(ormetric units).ThissystembecamecodifiedbyinternationaltreatyinFrancein1875. Mostunitsystemstoday,includingtheBritishImperialSystemandtheUSCS, arereferencedtotheactualexistingweights(mass)andmeasuresoftheSIunits. ThesereferenceweightsandmeasuresarekeptinParis,Franceforallnations andotherentitiestoutilize.Since1875,theSIunitshavegainedrapidandwidespreadusethroughouttheworld.Thissystemischaracterizedbyitsconsistent setofunitsandsimplicityofuse.TheSIunitsarebasedonmultiplesofdecades orunitsof10s.AllbasicweightsandmeasurementunitswithinSIareinincreasingmagnitudesofmultiplesof10,100,1000,etc.Nearlyallotherunitsystemsin useininternationaltradeandcommercearoundtheworldtodaymustbereferencedagainsttheSIstandardunitsbeforetheyareconsideredlegitimateforlegal mattersorforinternationalcommercialtrade.
1.4.1 PhysicalMechanics Thereareimportantfundamentaldefinitionsofunitsthatmustbeusedtodefine anyunitssystem.Theseare:
- Force istheactionofonebodyonanother,whichwillcauseaccelerationof thesecondbodyunlessactedonbyanequalandoppositeactioncountering theeffectofthefirstbody.
- Time isameasureofthesequenceofevents.InNewtonianmechanics,time isanabsolutequantity.Inrelativisticmechanics,itisrelativetothe frameof reference inwhichthesequenceofeventsisobserved.Thecommonunitof timeisseconds.
- Inertia isthatpropertyofmatterthatcausesaresistancetoanychangein themotionofabody.
- Mass isaquantitativemeasureof inertia
ThismonographwilldealexclusivelywithNewtonianmechanics.Newton’sGeneralLawsare:
LawI. Ifabalancedforcesystemactsonaparticleatrest,itwillremainatrest. Ifabalancedforcesystemactsonaparticleinmotion,itwillremaininmotion inastraightlinewithoutacceleration.
LawII. Ifanunbalancedforcesystemactsonaparticle,itwillacceleratein proportiontothemagnitudeandinthedirectionoftheresultantforce.
LawIII. Whentwoparticlesexertforcesoneachother,theseforcesareequal inmagnitude,oppositeindirection,andcollinear.
NotethattheaboveoriginaldefinitionsoftheabovelawsbyNewtonwereconceivedaroundtheconceptofforce.
1.4.2 BasicUnitsandUsage TheUSCSisa gravitational systemsinceitsunitsof length, force,and time (i.e., L, F,and T,respectively)areconsideredfundamentaldimensionsofthesystem andallotherunitsincluding mass arederived.TheSIisan absolute systemsince itsunitsof length, mass,and time (i.e., L, M,and T,respectively)areconsidered fundamentaldimensionsofthesystemandallothersunitsincluding force canbe derived.
Thereasonforthisdistinctionbetween gravitational and absolute isthelaudabledesirethattheconceptandmagnitudeofthemassofanobjectshould remainthesameregardlessofwhereitiswithrespecttootherobjectsthatwould influenceitthroughgravitationalattraction.Inthismanner,theSIwouldbein accordancewithNewton’sUniversalGravitationthatdescribestheuniversality ofgravity(Newton’sUniversalGravitationisanextensionofNewton ’sGeneral LawIIabove).TheaverageforceofgravitationalattractionisshownmathematicallyinNewton’sUniversalGravitationby
where Fgravity isthegravitationalattractionforce(lb,N), G isaconstantof proportionality(3.437 10 8 lb-ft2/slug2,or6.673 10 11 N/m2/kg2), m1 is Mass1(slug,kg), m2 isMass2(slug,kg),and d isthedistancebetweenthe masses(ft,m).
Newton’sLawIIcanbewrittenas
where F istheforcebeingappliedtoamassneartheearth’ssurface(lb,N), m is anyobjectmass(slug,kg),and a istheresultantaccelerationofthatmassasa resultoftheappliedforce F (ft/sec 2,m/sec2).
Ifamassisonorneartheearthsurface,theforceofattractionofthemassto theearth’smassbecomesthespecialforcedenotedasweight(assumingnoother forcesactonthemass).Inthissituation,theaccelerationterm a becomes g, whichisthegravitationaccelerationofthemassfallingfreelytowardtheearth’s center.Substituting g intoEquation (1-2) andlettingthe F termsinEquations (1-1) and(1-2) equaleachother, g becomes
Substitutingtherespectiveunitsystemvaluesandearth’saveragemassatmidlatitudesandthedistancebetweenthecenteroftheearthandtheobjectnear theearth’ssurfacegivestheaccelerationtermthatisusedinmostpracticalengineeringmechanicsproblems. Table1-1 givesthevaluesof g forboththeUSCS andSI.Thehighaccuracyvaluesaregivenwiththecommonlyusedengineering values.
NotethattheEarthisnotaperfectsphere;therefore,theaccelerationofgravitywillbeslightlydifferentdependingonwhetherthefreefallingbodyisata poleorattheequator.Theellipticalformoftheearthdictatesthattheaccelerationofgravitywillbeslightlygreaterattheequatorthanatthepoles.Formost engineeringapplicationsatorneartheearth’ssurface,theaverageacceleration ofgravity(engineer)termsisusedforcalculationpurposes.Bothofthesecalculationsweremadeusingtheexactsamecalculationmethod.Nospecialtermor constantwasemployedtoobtaineitheroftheaboveresults.
Theobjectiveofthethirdeditionofthismonographistoallowengineersand othertechnologiststocarryouttherequiredairandgasdrillingcalculationin bothUSCSandSIunits.Inparticular,theobjectiveisforengineersandtechnologistswhopresentlyuseUSCSunitstolearntobecomfortableusingtheSIunits. Mostexamplesdiscussedwithinthismonographaresteady-stateflowproblems.
Table1-1 AccelerationofGravity
Tofacilitatethisobjective,twominoralterationsinSIcommonusagehavebeen madebytheauthorstoallowforamoreunifiedmethodofcalculationmanipulationthatarecommontotheusageofUSCSunits.Thiswillallowfortransparencyinthemanipulationofbothsystemsthatpractitionersworkinginboth systemswillrecognize.
Nearlyallequationsinthismonographarederivedforusewithanyconsistent setofunits.Further,sincemostequationsintheeditionareforsteady-stateflow, theequationswillhavefewmass(m)orgravityacceleration(g)terms.Therefore, thefirstalterationfromtraditionalSIusagewillbethatanySIdataortermsthat contain kg unitsaretobechangedtoforceunits(N)bymultiplyingappropriately by9.8m/sec2.Anexampleofthisfirstalterationwouldbethewritingofpower inSIunitsasN-m/sec(Watt)insteadoftheSIpuristformofthepowerunitof kgm2/sec3 (whichisalsoaWatt).ThesecondalterationfromtraditionalSIuse willbethatfluidflowpressurewillbegivenin N/cm2 insteadofthemoreSIpurist recognizedPascal(N/m2).Regardingthelateralteration,itisverydifficultfor eithertheUSCSortheSIpractitionertovisualizetheforceperunitareamagnitudebeingappliedwithpressuretotheinsideflowareaofa2-inch (50.8mm) nominaldiameterpipe,orappliedasstresstoasmallmachinepartwhenthearea ofthepressureorstressunitismanytimesgreaterthantheareaoftheactualflow areaorstressarea.Therefore,asisthepracticeintheUSCSformostapplications, whereapressureorstressiscalculatedinlb/ft2,thesevaluesareconvertedto lb/in2 (psi).Likewise,forSI,thePascal(N/m2)willbeconvertedto N/cm2. Inessence,theauthorsrecommendanalyzingtheSIsystemjustliketheUSCS inthatbotharetreatedasanF,L,andTsystem,insteadoftreatingtheSIasanM, L,andTsystem.EventhoughthislogicmayannoytheSIpurist,itwillbeshown thatemployingtheSImassconcept(andtheUSCSmassconcept)inthismanner isfarsuperiortoemployingthecobbled-upunitconversionsthatdefineforce andmassintheUSCSas lbf and lbm,andtheusetheassociatedartificialconstants gc and go.TheauthorshaveevenseenthisconversionconceptappliedtotheSI unitsintheformof Nf and Nm withtheirassociatedartificialconstants gc and go.It issuspectedthatthismisguidedconversioncreationwasdevelopedbychemical andmechanicalengineeringprofessorswhoweremotivatedbythedesireto haveaheattransferequationthatisinconsistentunitsusingthemassunit (insteadoftheweightunit).Sincespecificheat cp intheSIisintheunitsof kcal/kg-K andintheUSCSisintheunitsof BTU/lb-R,aheattransferequation forSIcalculationswouldhavetobeinmassrateofflow dm/dt andaheattransfer equationfortheUSCSwouldhavetobeinweightrateofflow dw/dt.Itisour contentionthatforthoseofuswhowerenotbroughtupusingtheSIasourprimarysystemofunits,itiseasierforengineerstocarryingoutcalculationsinboth systemsifbothunitsystemsaremanipulatedinexactlythesamemanner.This requirestheuseofthekilogramdefinitiongivenin Table1-2.Itislikelythatthis kilogramdefinitionwill “rufflethefeathers” ofsomeSIpurists. Thereisoneotherimportantchangethatwillbemadeintheapplicationof theSItothedrillingcalculationsmadeinthismonograph.Theuseofthe N/m2 or
Table1-2 TheUnitsThatDefineMass UnitSystemMassUnitDimensions
USCS SlugFT2/L ¼ lbsec2/ft SI KilogramFT2/L ¼ Nsec2/m
FIGURE1-1 PressuregaugewithbothpsiandN/cm2 units.
the Pascal (Pa)asapressureunitwillnotbeused.Mostengineershavetrouble correlatingthesevaluestosmallcross-sectionalareassuchasa2-inchnominal pipe( i.d.of2.0inchor50.8mm).Initsplace,wewilluseapressuretermunit of N/cm2.Itisonlynecessarytomultiplythispressureunitby104 toobtainpressurein pascals,orby0.6897toobtainpsi.Theconvenienceofusingthisalternate SIpressuretermisillustratedby Figure1-1,wherebothscalescanbeplacedeasilyonthesamegaugefaceforeasyreading(andreferencetooneanother).
REFERENCES [1] R.E.Daugherty,J.B.Franzini,E.J.Finnemore,FluidMechanicsWithEngineering Applications,eighthed.,McGraw-Hill,1985.
[2] SPEAlphabeticalListofUnits,SPEPublications,2006.
AirandGasVersusMud 2 Thisengineeringpracticemonographhasbeenpreparedforpetroleumand relateddrillingandcompletionengineersandtechnicianswhoworkinmodern rotarydrillingoperations.Thebookderivesandillustratesengineeringcalculationtechniquesassociatedwithairandgasdrillingtechnology.Themanualhas beenwritteninconsistentunitsforeaseofapplicationineitherUSCSorSI.Also, fieldunitequationusehasbeenminimizedinthetext. Chapter1 and AppendixA givedefinitionsofimportantunitsandconstantsandusefulconversionsforboth USCSandSI.
Airandgasdrillingtechnologyistheutilizationofcompressedairorother gases,asarotarydrillingcirculatingfluid,tocarrytherockcuttingstothesurface thataregeneratedatthebottomofthewellbytheadvanceofthedrillbit.Also entrainedinthiscirculatingaircanbesurfaceinjectfluids(e.g.,foamagent, water,and/orlubricationoil).Thefoamagentwillhelpwithcontrollinganybottomholeformationfluidsthatareencounteredasthedrillbitisadvanced.There arethreedistinctoperationalapplicationsforthistechnology:(1)airorgasdrillingoperations(usingonlythecompressedairorothergasasthecirculating fluid),(2)aerateddrillingoperations(usingcompressedairorothergasmixed withanincompressiblefluid),and(3)stablefoamdrillingoperations(usingthe compressedairorothergaswithafoamingagentfluidtocreateacontinuous foamcirculatingfluid).
Inthepast,airandgasdrillingmethodshavebeenasmallsegmentofthe petroleumdepositrecoverydrillingindustry.Currently,thesedrillingmethods compriseabout10%ofalloilandgasdrillingoperations.Therearetwoseparate anduniquereasonswhythepetroleumindustryisinterestedinutilizingtheseair drillingmethods.Theseare:
Performancedrilling:Rapiddrillingoftheoverburdenformationsthat overlayapotentialtargetproducingformation.Thistactictakesadvantage oftheincreasedratesofpenetrationofthevariousairandgasdrilling techniquestoreducethetimeandcosttocompleteawellandgetitinto production.
Underbalanceddrilling:Drillingintoapotentialproducingcrudeoilor naturalgasformationhavinganannulusbottomholepressurethatis belowthetargetformationporepressure.Thistacticreducesoreliminates formationdamage,whichcannegativelyaffecttheefficiencyoffollow-on productionfromthewell.
AirandGasDrillingManual. https://doi.org/10.1016/B978-0-12-815792-3.00002-7 # 2021ElsevierInc.Allrightsreserved.
Ingeneral,airandgasdrillingmethodsareconfinedtomaturesedimentary basinswithinmaturegeologicprovinces.
Historically,pneumaticconveyingrepresentedthefirstuseofhigh-speed movingairflowstotransportentrainedsolidsintheflowingstreamofair.This airstreamwascreatedbysteam-poweredfansthatwerethedirectoutgrowthof theindustrialrevolutionoftheearlysixteenthcentury.Pneumaticconveyingwas accomplishedonanindustrialscalebythelate1860s [1].Theneedforhigher pressureflowsofairandothergasesledtothedevelopmentofthefirstreliable industrialaircompressorsinthelate1870s [2].Hereagain,theseearlycompressorsweresteampowered.Afterthedevelopmentoftheinternalcombustion engines,portablereciprocatingandrotarycompressorswerepossible.These portablecompressorswerefirstutilizedinthelate1880sbyaninnovativemining industrytodrillinminesusingpneumaticactuatedhammerstobreakuprock facesinminesandtodrillshallowpilotboreholesforshaftconstruction [2]
2.1 ROTARYDRILLING Theveryfirstorganizedmethodfordrillingverticalsubserviceboreholesisthe cabletoolmethod.ItisbelievedthattheChinesewerethefirsttousethecable toolmethodwithbamboopolestippedwithsharprockdrillbitstoborevertical wellsasearlyas5000BC.Moderncabletoolequipmentisstillmanufacturedand isprimarilyusedtodaytodrillshallowwaterwell.Tabletoolmethodhasdepth limitations,generallylessthanabout3000ft(900m).
Becauseofthecabletoolmethoddepthlimitations,therotarydrillingmethod wasdevelopedbyaFrenchcivilengineer,RudolfLeschotin1863 [3].Itwas developedatthattimetoprovideamoreefficientmethodtodrilldeepwater wells.Themodernrotarydrillingequipmentandmethodsarepresentlyused todrilldeepwellsfromonshoreandoffshorelocationsforboththepetroleum andgeothermalindustries.Today,verticalandhigh-angledirectionalwellsare routinelydrilledwithrotarydrillingmethodstoverticaldepthsof20,000ft (6100m),andwithlateraloffsetsof10,000ft(3050m) Nearlyallofthesewells havebeendrilledwithincompressiblecirculationdrillfluidsoffreshwateror engineereddrillingmuds.Itislikelythatwhenthefirstaircompressorsbecame availabletothedrillingindustry,theywereusedtorotarydrillshallowwater wells.Itisknownthatdeeppetroleumandnaturalgaswellsweredrilledutilizing portableaircompressorsinthe1920s [4].Pipelinegaswasusedtodrillanatural gaswellinTexasin1935usingreversecirculationtechniques [5].
Todayrotarydrillingisusedtodrillavarietyofboreholes.Mostwaterwells andenvironmentalmonitoringwellsdrilledintobedrockareconstructedusing rotarydrilling.Intheminingindustry,rotarydrillingisusedtodrillorebodytest boreholesandpilotboreholesforguidinglargershaftborings.Rotarydrilling techniquesareusedtodrillboreholesforwater,oil,gas,andotherfluidpipelines thatneedtopassunderrivers,highways,andothernaturalandman-made
obstructions.Mostrecently,rotarydrillingisbeingusedtodrillboreholesfor fiberopticsandothertelecommunicationlinesinobstacle-riddenareassuch ascitiesandindustrialsites.Themostsophisticatedapplicationforrotarydrilling isthedrillingofdeepboreholesfortherecoveryofnaturalresourcessuchas crudeoil,naturalgas,andgeothermalsteamandwater.Drillingboreholesfor fluidresourcerecoveryusuallyrequiresboreholesdrilledfromasshallowas 3000ft(900m)toasdeepas20,000ft(6000m)
Rotarydrillingforgeothermaldeposits(i.e.,naturalsteamandsuperheated geothermalwaters)requiresdrillingthrough “hardrock,” metamorphicand igneousrock(aswellassedimentaryrock).However,thedeepdrillingofboreholesfortherecoveryofcrudeoilandnaturalgasisalmostexclusivelycarried outinsedimentaryrock.Therotarydrillingmethodrequirestheuseofarock cuttingand/orcrushingdrillbit. Figure2-1 showsatungstencarbideinsert tri-conerollerconebit.Thistypeofdrillbitusesmoreofacrushingactionto advancethebitintherock(see Chapter4 formoredetails).Thesebitsareused primarilytodrillmediumhardsedimentaryrock.
Toadvancethedrillbitinrockrequirestheapplicationofanaxialforceonthe bit(topushthebitintotherockface),torqueonthebit(torotatethebitagainst theresistanceoftherockface),andcirculatingfluidtocleartherockcuttings
FIGURE2-1 Tungstencarbideinsert77/8inch(200.1mm)tri-conerollercutterbitIADC Code627.
(CourtesyofHughesChristensenIncorporated.)
Axial force
Fluid circulation
Rotation/torque
Thethreenecessarycomponentsforrotarydrilling.
Table2-1 APILengthRangesforDrillCollarsandDrillPipe
RangesMinimumLengthMaximumLength
awayfromthebitasthebitgeneratesmorecuttingswithitsadvance(see Figure2-2).Iftheaxialforceismissingandtheothertwoprocessesareoperating,thenthebitwillnotadvance.Likewise,iftorqueisnotpresentandtheother twoprocessesareoperating,thenagainthebitwillnotadvance.However,ifcirculationisnotpresentandtheothertwoprocessesarepresent,thedrillstring willlikelybedamaged.Thislittlediscussionemphasizesthecriticalnatureof thecirculatingsystem.
Rotarydrillingiscarriedoutwithavarietyofdrillingrigs.Thesecanbesmall “single” rigs,orlarger “double” and “triple” rigs.Todaymostofthedrillingrigs basedonlandaremobileunitswithfoldingmasts.Asingledrillingrighasaverticalspaceinitsmastforonlyonejointofdrillpipe.Adoubledrillingrighasa verticalspaceinitsmastfortwojointsofdrillpipeandatripledrillingrighasa verticalspaceforthreejoints. Table2-1 givestheAPIlengthrangesfordrillcollarsanddrillpipe [6].
FIGURE2-2
Typicalself-propelledsingledrillingrig. (CourtesyofGeorgeE.FailingCompany.)
Figure2-3 showsatypicalsingledrillingrig.Suchsmalldrillingrigsarehighly mobileandareusedprincipallytodrillshallow(lessthan3000ft,or 900m in depth)coal-bedmethanewellsandgeothermalhotwater-producingboreholes. Thesesinglerigsareusuallyself-propelled.Theself-propelleddrillingrigin Figure2-3 isaGardnerDenverSD55.ThisparticularrigusesRange2drillpipe. Singlerigscanbefittedwitheitheranon-boardaircompressororanonboardmudpump.Someoftheserigscanaccommodatebothsubsystems.These rigshaveeitheradedicatedprimemoverontherigdeckorapower-take-offsystemthatallowsutilizationofthetruckmotorastheprimemoverforthedrilling rigequipment(whenthetruckisstationary).Smalldrillingrigsusuallyprovide theaxialforcetopushthedrillbitintotherockfaceviaachainorcable-actuated pull-downsystem,orahydraulic-actuatedpull-downsystem.Apull-downsystemtransfersaportionoftheweightoftherigtothetopofthedrillstring andthenthroughthedrillstringtothedrillbit.Thetorqueandrotationat thetopofthedrillstringarealsooftenprovidedbyahydraulictop-headdrive (similartopowerswivelsystemsusedonlargerdrillingrigs),whichismovedup anddownthemast(onatrack)bythechain,cable,orhydraulicdrivepull-down system.However,someoftheserigsretainthetraditionalrotarytable.Manyof thesesmallsingledrillingrigsarecapableofdrillingwiththeirmastsatanglesas highas45° angletothevertical.Theprimemoverfortheserigsisusuallyfueled byeitherpropaneordiesel.
Theschematiclayoutin Figure2-4 showsatypicalself-propelleddoubledrillingrig.Thisexamplerigisfittedwithamudpumpforcirculatingdrillingmud.
FIGURE2-3
HYDRAULIC RESERVOIR
DOUBLE-DRUM DRAW WORKS WITH SANDREEL CATHEAD
SUPPORT JACKS DRILLER’S STATION
FIGURE2-4 Typicalself-propelleddoubledrillingrigschematiclayout.
TRAVELING BLOCK “CROWS NEST”
ROTARY TABLE KELLY HOSE SWIVEL MAST CROWN BLOCK
Whenthevehicleisstationaryandisbeingriggedbythecrewtoinitiateadrilling operation,thetransmissionsystemonthevehiclecanbeshiftedtotransferthe powerfromtheoverroadwheelstopoweringthedrillingequipmentcarriedon thevehicle.Thisiscalleda “power-take-off” capability. Fortherigshownin Figure2-4 ,thispower-take-offmotoroperatesa hydraulicpumpthatprovidesfluidtohydraulicmotorstooperatetherotary table,thedrawworks,andthemudpump.The “crow ’snest ” onthemastindicatesthattherigiscapableofdrilling withastandoftwojointsofdrillpipe. Thisdrillingrigutilizesarotarytableandakellytoprovidetorquetothetopof thedrillstring.Theaxialforceonthebitisprovidedbytheweightofthedrill
AIR COMPRESSOR
MUD PUMP
collarsatthebottomofthedrillstring(thereisnochainpull-downcapability forthisdrillingrig).Thisexampleschematicshowsarigwithon-boardequipmentthatcanprovideonlydrillingmudo rtreatedwaterasacirculationfluid. Thesmallaircompressoratthefrontoftherigdeckisusedtooperatethepneumaticcontrolsoftherig.However,thisrigcaneasilybefittedforairandgas drillingoperations.Thistypeofdrilli ngrig(alreadyfittedwithamudpump) requiresanauxiliaryhook-uptoexternalaircompressor(s)tocarryoutanair drillingoperation.Thecompressorsystemanditsassociatedequipmentforair drillingoperationsareusuallyprovidedbyasubcontractorspecializingin theseoperations.
Figure2-5 showsanewtypeoftripledrillingrigforlandoperations.Thisrig isfittedwithapowerswivelinsteadofarotarytable.ThesenewFlexRigsmust beassembledatthedrillinglocation.
Inadditiontohavingthemostmoderndrillingequipment(automaticpipe loader,singleconsoleoperation,etc.),thedesignuniquenessoftheFlexRigconceptallowsrapidrig-upandrig-down,whichminimizesnondrillingtimeatthe
location.TheserigshavebeendevelopedbyHelmerich,andPayneincorporated aninternationaldrillingcontractorservingbothon-landandoff-shoredrilling operations.Theserigsareavailableindepthcapabilitiesupto18,000ft(5500m).
2.2 CIRCULATIONSYSTEMS Twotypesofcirculationtechniquescanbeusedforeitheramuddrillingsystem oranairorgasdrillingsystem.Theyaredirect(conventional)circulationand reversecirculation.
2.2.1 DirectCirculation Figure2-6 showsaschematicofarotarydrilling,directcirculationmudsystem thatisusedonatypicaldouble(andtriple)drillingrig.Directcirculationrequires thatthedrillingmud(ortreatedwater)flowfromtheslushpump(ormud pump),throughthestandpipeonthemast,throughtherotaryhose,through
FIGURE2-6 Directcirculationmudsystem.
theswivelanddowntheinsideofthekelly,downtheinsideofthedrillpipeand drillcollars,throughthedrillbit(atthebottomoftheborehole)intotheannulus spacebetweentheoutsideofthedrillstringandtheinsideoftheborehole.
Thedrillingmudentrainstherockbitcuttingsatthebottomoftheannulus andthenflowswiththecuttingsuptheannulustothesurfacewherethecuttings areremovedfromthedrillingmudbytheshaleshakerandthedrillingmudis returnedtothemudtanks(wheretheslushpumpsuctionsidepicksupthedrillingmudandrecirculatesthemudbackintothewell).Theslushpumpsusedon double(andtriple)drillingrigsarepositivedisplacementpiston-typepumps.
Forsmallsingledrillingrigs,thedrillingfluidintheon-board “mud” tankis oftentreatedwithfreshwater.Aheavydutyhoseisrunfromthesuctionsideof theon-boardmudpump(see Figure2-4)tothemudtank.Thedrillingwateris pumpedfromthetank,throughthepump,throughanon-boardpipesystem, throughtherotaryhose,throughthehydraulictop-headdrive,downtheinside ofthedrillpipe,andthroughthedrillbittothebottomofthewell.Thedrilling waterthenentrainstherockcuttingsfromtheadvanceofthebitandcarriesthe cuttingstothesurfaceviatheannulusbetweentheoutsideofthedrillpipeand theinsideoftheborehole.Atthesurface,thedrillingfluid(water)fromtheannuluswithentrainedcuttingsisreturnedtoamudpitwheretherockcuttingsare allowedtosettledowntothebottom.Thepumpsonsingledrillingrigsaresmall positivedisplacementreciprocatingpistontype.
Figure2-7 showsadetailedschematicofadirectcirculationcompressedair drillingsystemusedonatypicaldoubleortripledrillingrig.
Directcirculationrequiresthatatmosphericairbecompressedbythecompressorandthenforcedthroughthestandpipeonthemast,throughtherotary hose,throughtheswivelanddowntheinsideofthekelly,downtheinsideofthe drillpipeanddrillcollars,throughthedrillbit(atthebottomoftheborehole) intotheannulusspacebetweentheoutsideofthedrillstringandtheinsideof theborehole.Thecompressedairentrainstherockbitcuttingsandthenflows withthecuttingsuptheannulustothesurfacewherethecompressedairwith theentrainedcuttingsexitsthecirculationsystemviatheblooeyline.Thecompressedairandcuttingsexittheblooeylineintoalargepitdugintotheground surface(burnpit).Thesepitsarelinedwithanimpermeableplasticliner.
Ifcompressednaturalgasistobeusedasadrillingfluid,agaspipelineisrun fromamainnaturalgaspipelinetothedrillingrig.Oftenthislineisfittedwitha boostercompressor.Thisallowsthepipelinenaturalgaspressuretobeincreased (ifhigherpressureisneeded)beforethegasreachesthedrillingrigstandpipe.
2.2.2 ReverseCirculation Figure2-8 showsatypicalreversecirculationflowsystemschematicforarotary drillingoperationusingdualwalldrillpipe.Rotarydrillingreversecirculation (usingeitherdrillingmudorcompressedairorgas)canbeausefulalternative
FIGURE2-7 Directcirculationoperationschematicusingcompressedairsystem.
todirectcirculationmethods.Thereversecirculationtechniqueisparticularly usefulfordrillingrelativelyshallowlargediameterboreholes(e.g.,conductor andsurfacecasingboreholes).
Inatypicalreversecirculationoperationutilizingdrilli ngmud,thedrilling mudflowsfromthemudpumptothetopoftheannulusbetweentheoutside ofthedrillstringandtheinsideoftheborehole,downtheannulusspaceto thebottomoftheborehole.Atthebottomoftheborehole,thedrillingmud entrainstherockbitcuttingsandflowsthroughthelargecenteropeningin thedrillbitandthenupwardtothesurfacethroughtheinsideofthedrill string.Atthesurface,thecuttingsareremovedfromthedrillingmudby theshaleshakerandthedrillingmudisreturnedtothemudtanks(where thepumpsuctionsidepicksupthedrillingmudandrecirculatesthemud backtothewell).
AIR OR MIST
CONTINUOUS SAMPLE DISCHARGE
TOP HEAD ROTARY DRIVE OUTER PIPE INNER PIPE FIGURE2-8 Reversecirculationoperationschematicusingdualwalldrillpipegivinganearly closed-loopcirculation.
Reversecirculationcanalsobecarriedoutusingairandgasdrillingtechniques. Figure2-8 showsatypicalapplicationofreversecirculationusingcompressedairasthedrillingfluid(ormist,unstablefoam) [7].Thisexampleisadual tube(ordualdrillpipe)closedreversecirculationsystem.Theclosedsystemis characterizedbyanannulusspaceboundedbytheinsideoftheoutertubeand
FIGURE2-9 Schematicoftheinternalflowchannelofatri-conerollercutterbitdesignedfor reversecirculationoperations.
(CourtesyofSmithInternationalIncorporated.)
theoutsideoftheinnertube.Thisisaspecializedtypeofreversecirculationand isusuallylimitedtosmallsingleanddoubledrillingrigswithtop-headrotary drives(see Chapter4 fordrillpipedetails).
Reversecirculationdrillingoperationsrequirespeciallyfabricateddrillbits. Figure2-9 showsaschematicoftheinteriorflowchannelofatri-conerotarydrill bitdesignedforreversecirculation.Thesedrillbitsutilizetypicalrollercutter conesexactlylikethoseusedindirectcirculationdrillbits(see Figure2-1).These bits,however,havealargecentralchannelopeningthatallowsthecirculation fluidflowwithentrainedrockcuttingstoflowfromthebottomoftheborehole totheinsideofthedrillstringandthentothesurface.
Mosttri-conedrillbitswithadiameterof53/4inches(146mm)orlessare designedwiththecentralflowchannelasshownin Figure2-9. Figure2-1 showedthetypicaltri-conedrillbitfordirectcirculationoperations.Thesedirect circulationdrillbitsusuallyhavethreeorificesthatcanbefittedwithnozzles. Tri-conerollercutterdrillbitsforreversecirculationoperationsareavailable indiametersfrom41/2inches(114mm)to31inches(787mm). Thelargerdiameterbitsforreversecirculationoperationsareusuallycustom-designedand fabricated.Dualwallpipereversecirculationoperationsrequirespecialskirted drillbits(see Chapter4 fordetails).Theseskirteddrillbitsarespecifically designedfortheparticulardrillingoperation.Thesespecializeddrillbitsare usuallymanufacturedbyminingequipmentcompanies.
