Acreage The following table sets forth as of December 31, 2012 the gross and net developed and undeveloped natural gas and oil leasehold and fee mineral acreage. "Gross" acres are the total number of acres in which we own a working interest. "Net" acres refer to gross acres multiplied by our fractional working interest. Acreage numbers do not include our unexercised options to acquire additional acreage. Developed Leasehold Gross Net Acres Acres Southern .................. Northern .................. Eastern .................... Western ................... Total.....................
1,018 4,606 1,972 625 8,221
653 2,458 1,497 355 4,963
Undeveloped Fee Minerals Leasehold Gross Net Gross Net Acres Acres Acres Acres (in thousands) 327 189 141 65 4,242 2,863 1,056 178 5,913 3,413 706 508 4,941 2,822 350 31 15,423 9,287 2,253 782
Total Gross Acres 1,486 9,904 8,591 5,916 25,897
Net Acres 907 5,499 5,418 3,208 15,032
We actively acquire new leases, most of which have a three to five-year term. Managing lease expirations to ensure that we do not experience unintended material expirations is an important part of our business. Our leasehold management efforts include scheduling our drilling to establish production in paying quantities in order to hold leases by production, timely exercising our contractual rights to pay delay rentals to extend the terms of leases we value, planning leasehold asset sales and joint venture transactions to high-grade our lease inventory or to raise capital for additional development and letting some leases expire that are no longer part of our development plans. The following table sets forth as of December 31, 2012, the expiration periods of gross and net undeveloped leasehold acres, unless production from the leasehold acreage is established prior to the expiration date, or we take action to extend the lease term. Acres Expiring Gross Net Acres Acres (in thousands) Years Ending December 31: 2013 ........................................................................................................................... 2014 ........................................................................................................................... 2015 ........................................................................................................................... After 2015 and other .................................................................................................. Total(a) ..................................................................................................................
2,684 3,442 2,243 7,054 15,423
1,533 2,430 1,360 3,964 9,287
___________________________________________ (a)
Includes held-by-production acreage that will remain in force as our production continues on the subject leases, and other leasehold acreage where management anticipates the lease to remain in effect past the primary term of the agreement due to our contractual option to extend the lease term.
Marketing, Gathering and Compression Marketing Chesapeake Energy Marketing, Inc. (CEMI), one of our wholly owned subsidiaries, provides natural gas, oil and NGL marketing services, including commodity price structuring, contract administration and nomination services for Chesapeake, its joint working interest owners and other producers. We attempt to enhance the value of our natural gas and oil production by aggregating volumes to be sold to various intermediary markets, end markets and pipelines. This aggregation allows us to attract larger, more creditworthy customers that in turn assist in maximizing the prices received for our production. Our oil and NGL production is generally sold under market sensitive short-term or spot price contracts. Our natural gas production is sold to purchasers under percentage-of-proceeds contracts, percentage-of-index contracts or spot 13