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CHESAPEAKE ENERGY CORPORATION AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS – (Continued)
Proved developed natural gas and oil reserves are reserves of any category that can be expected to be
recovered through existing wells with existing equipment and operating methods or in which the cost of the
required equipment is relatively minor compared to the cost of a new well.
The information below on our natural gas and oil reserves is presented in accordance with regulations
prescribed by the Securities and Exchange Commission as in effect as of the date of such estimates.
Chesapeake emphasizes that reserve estimates are inherently imprecise. Our reserve estimates are generally
based upon extrapolation of historical production trends, analogy to similar properties and volumetric
calculations. Accordingly, these estimates are expected to change, and such changes could be material and
occur in the near term as future information becomes available.
Presented below is a summary of changes in estimated reserves of Chesapeake for 2010, 2009 and 2008:
Gas
(bcf)
Oil
(mmbbl)
Total
(bcfe)
December 31, 2010
Proved reserves, beginning of period ............................. 13,510 124.0 14,254
Extensions, discoveries and other additions ....................... 4,678 70.0 5,098
Revisions of previous estimates ................................. (445) 104.6 183
Production ................................................... (925) (18.4) (1,035)
Sale of reserves-in-place ....................................... (1,426) (11.2) (1,493)
Purchase of reserves-in-place ................................... 63 4.4 89
Proved reserves, end of period .................................. 15,455 273.4 17,096
Proved developed reserves:
Beginning of period ........................................ 7,859 78.8 8,331
End of period ............................................. 8,246 149.3 9,143
December 31, 2009
Proved reserves, beginning of period ............................. 11,327 120.6 12,051
Extensions, discoveries and other additions ....................... 4,530 27.1 4,693
Revisions of previous estimates ................................. (1,335) (10.3) (1,397)
Production ................................................... (835) (11.8) (906)
Sale of reserves-in-place ....................................... (209) (1.8) (220)
Purchase of reserves-in-place ................................... 32 0.2 33
Proved reserves, end of period .................................. 13,510 124.0 14,254
Proved developed reserves:
Beginning of period ........................................ 7,582 84.9 8,091
End of period ............................................. 7,859 78.8 8,331
December 31, 2008
Proved reserves, beginning of period ............................. 10,137 123.6 10,879
Extensions, discoveries and other additions ....................... 1,526 11.5 1,595
Revisions of previous estimates ................................. 957 (1.2) 950
Production ................................................... (775) (11.2) (843)
Sale of reserves-in-place ....................................... (674) (4.6) (702)
Purchase of reserves-in-place ................................... 156 2.5 172
Proved reserves, end of period .................................. 11,327 120.6 12,051
Proved developed reserves:
Beginning of period ........................................ 6,409 88.8 6,942
End of period ............................................. 7,582 84.9 8,091
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