Annual Report 2012

(D) SUPPLEMENTAL INFORMATION ON OIL AND GAS PRODUCING ACTIVITIES (UNAUDITED) (CONTINUED)
Table IV: Reserve quantities information
The Group’s estimated net proved underground oil and gas reserves and changes thereto for the years ended 31 December 2012 and 2011 are shown
in the following table.
Proved oil and gas reserves are those quantities of oil and gas, which by analysis of geoscience and engineering data, can be estimated with reasonable
certainty to be economically producible from a given date forward, from known reservoirs, and under existing economic conditions, operating methods,
and government regulation before contracts providing the right to operate expire, unless evidence indicates that renewal is reasonably certain,
regardless of whether the estimate is a deterministic estimate or probabilistic estimate. Due to the inherent uncertainties and the limited nature of
reservoir data, estimates of underground reserves are subject to change as additional information becomes available.
Proved developed oil and gas reserves are proved reserves 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 with the cost of a new well.
“Net” reserves exclude royalties and interests owned by others and reflect contractual arrangements in effect at the time of the estimate.
2012 2011
Proved developed and undeveloped reserves (oil) (million barrels)
Beginning of year 2,848 2,889
Revisions of previous estimates 9 126
Improved recovery 163 72
Extensions and discoveries 151 82
Production (328) (321)
End of year 2,843 2,848
Non-controlling interest in proved developed and undeveloped reserves at the end of year 32 36
Proved developed reserves
Beginning of year 2,545 2,554
End of year 2,577 2,545
Proved undeveloped reserves
Beginning of year 303 335
End of year 266 303
Proved developed and undeveloped reserves (gas) (billion cubic feet)
Beginning of year 6,709 6,447
Revisions of previous estimates 278 (74)
Improved recovery 109 4
Extensions and discoveries 232 849
Production (598) (517)
End of year 6,730 6,709
Proved developed reserves
Beginning of year 4,246 4,471
End of year 5,439 4,246
Proved undeveloped reserves
Beginning of year 2,463 1,976
End of year 1,291 2,463
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CHINA PETROLEUM & CHEMICAL CORPORATION Annual Report 2012
Financial Statements
Supplemental Information on Oil and
Gas Producing Activities (Unaudited)