"Prepared" reserves are those quantities of reserves that were prepared by an independent petroleum consultant. "Audited" reserves are those quantities of revenues that were estimated by Devon employees and audited by an independent petroleum consultant. An audit is an examination of a company's proved oil and gas reserves and net cash flow by an independent petroleum consultant that is conducted for the purpose of expressing an opinion as to whether such estimates, in aggregate, are reasonable and have been estimated and presented in conformity with generally accepted petroleum engineering and evaluation principles.
The domestic reserves were evaluated by the independent petroleum consultants of LaRoche Petroleum Consultants, Ltd. and Ryder Scott Company, L.P. in each of the years presented. The Canadian reserves were evaluated by the independent petroleum consultants of AJM Petroleum Consultants in each of the years presented. The International reserves were evaluated by the independent petroleum consultants of Ryder Scott Company, L.P. in each of the years presented.
Set forth below is a summary of the changes in the net quantities of crude oil, natural gas and natural gas liquids reserves for each of the three years ended December 31, 2007. Additional discussion of the significant proved reserve changes follows the tables below.
| Total | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Oil (MMBbls) |
Gas (Bcf) |
Natural Gas Liquids (MMBbls) |
Total (MMBoe) |
|||||||||
| Proved reserves as of December 31, 2004 | 484 | 7,385 | 232 | 1,946 | ||||||||
| Revisions due to prices | (12 | ) | 79 | 4 | 5 | |||||||
| Revisions other than price | 19 | (7 | ) | 16 | 35 | |||||||
| Extensions and discoveries | 166 | 1,220 | 30 | 399 | ||||||||
| Purchase of reserves | 2 | 10 | — | 4 | ||||||||
| Production | (46 | ) | (819 | ) | (24 | ) | (206 | ) | ||||
| Sale of reserves | (58 | ) | (676 | ) | (12 | ) | (183 | ) | ||||
| Proved reserves as of December 31, 2005 | 555 | 7,192 | 246 | 2,000 | ||||||||
| Revisions due to prices | (22 | ) | (87 | ) | (7 | ) | (44 | ) | ||||
| Revisions other than price | 4 | (107 | ) | 5 | (8 | ) | ||||||
| Extensions and discoveries | 139 | 1,490 | 45 | 433 | ||||||||
| Purchase of reserves | — | 584 | 9 | 106 | ||||||||
| Production | (42 | ) | (808 | ) | (23 | ) | (200 | ) | ||||
| Sale of reserves | — | (5 | ) | — | (1 | ) | ||||||
| Proved reserves as of December 31, 2006 | 634 | 8,259 | 275 | 2,286 | ||||||||
| Revisions due to prices | 11 | 169 | 5 | 44 | ||||||||
| Revisions other than price | 31 | 155 | 20 | 75 | ||||||||
| Extensions and discoveries | 56 | 1,272 | 47 | 315 | ||||||||
| Purchase of reserves | 1 | 15 | — | 3 | ||||||||
| Production | (55 | ) | (863 | ) | (26 | ) | (224 | ) | ||||
| Sale of reserves | (1 | ) | (13 | ) | — | (3 | ) | |||||
| Proved reserves as of December 31, 2007 | 677 | 8,994 | 321 | 2,496 | ||||||||
|
Proved developed reserves as of: December 31, 2004 |
332 | 6,177 | 204 | 1,566 | ||||||||
| December 31, 2005 | 306 | 6,073 | 216 | 1,535 | ||||||||
| December 31, 2006 | 318 | 6,484 | 229 | 1,628 | ||||||||
| December 31, 2007 | 391 | 7,255 | 274 | 1,874 | ||||||||
| Domestic | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Oil (MMBbls) |
Gas (Bcf) |
Natural Gas Liquids (MMBbls) |
Total (MMBoe) |
|||||||||
| Proved reserves as of December 31, 2004 | 203 | 4,936 | 182 | 1,208 | ||||||||
| Revisions due to prices | 6 | 58 | 3 | 19 | ||||||||
| Revisions other than price | 2 | 238 | 19 | 61 | ||||||||
| Extensions and discoveries | 16 | 793 | 20 | 169 | ||||||||
| Purchase of reserves | — | — | — | — | ||||||||
| Production | (25 | ) | (555 | ) | (18 | ) | (136 | ) | ||||
| Sale of reserves | (29 | ) | (306 | ) | (9 | ) | (89 | ) | ||||
| Proved reserves as of December 31, 2005 | 173 | 5,164 | 197 | 1,232 | ||||||||
| Revisions due to prices | — | (110 | ) | (3 | ) | (22 | ) | |||||
| Revisions other than price | — | (11 | ) | 6 | 5 | |||||||
| Extensions and discoveries | 16 | 1,298 | 43 | 274 | ||||||||
| Purchase of reserves | — | 580 | 9 | 105 | ||||||||
| Production | (19 | ) | (566 | ) | (19 | ) | (132 | ) | ||||
| Sale of reserves | — | — | — | — | ||||||||
| Proved reserves as of December 31, 2006 | 170 | 6,355 | 233 | 1,462 | ||||||||
| Revisions due to prices | 4 | 119 | 5 | 29 | ||||||||
| Revisions other than price | 6 | 174 | 21 | 56 | ||||||||
| Extensions and discoveries | 9 | 1,133 | 45 | 242 | ||||||||
| Purchase of reserves | 1 | 10 | — | 2 | ||||||||
| Production | (19 | ) | (635 | ) | (22 | ) | (146 | ) | ||||
| Sale of reserves | (1 | ) | (13 | ) | — | (3 | ) | |||||
| Proved reserves as of December 31, 2007 | 170 | 7,143 | 282 | 1,642 | ||||||||
|
Proved developed reserves as of: December 31, 2004 |
168 | 4,105 | 161 | 1,014 | ||||||||
| December 31, 2005 | 149 | 4,343 | 175 | 1,049 | ||||||||
| December 31, 2006 | 147 | 4,916 | 196 | 1,163 | ||||||||
| December 31, 2007 | 148 | 5,743 | 244 | 1,349 | ||||||||
| Canada | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Oil (MMBbls) |
Gas (Bcf) |
Natural Gas Liquids (MMBbls) |
Total (MMBoe) |
|||||||||
| Proved reserves as of December 31, 2004 | 147 | 2,420 | 50 | 600 | ||||||||
| Revisions due to prices | — | 22 | 1 | 4 | ||||||||
| Revisions other than price | 2 | (242 | ) | (3 | ) | (41 | ) | |||||
| Extensions and discoveries | 144 | 427 | 10 | 225 | ||||||||
| Purchase of reserves | 2 | 10 | — | 4 | ||||||||
| Production | (13 | ) | (261 | ) | (6 | ) | (62 | ) | ||||
| Sale of reserves | (29 | ) | (370 | ) | (3 | ) | (94 | ) | ||||
| Proved reserves as of December 31, 2005 | 253 | 2,006 | 49 | 636 | ||||||||
| Revisions due to prices | (19 | ) | 23 | (4 | ) | (20 | ) | |||||
| Revisions other than price | (1 | ) | (84 | ) | (1 | ) | (16 | ) | ||||
| Extensions and discoveries | 109 | 193 | 2 | 145 | ||||||||
| Purchase of reserves | — | 4 | — | 1 | ||||||||
| Production | (13 | ) | (241 | ) | (4 | ) | (58 | ) | ||||
| Sale of reserves | — | (5 | ) | — | (1 | ) | ||||||
| Proved reserves as of December 31, 2006 | 329 | 1,896 | 42 | 687 | ||||||||
| Revisions due to prices | 16 | 50 | — | 25 | ||||||||
| Revisions other than price | 13 | (19 | ) | (1 | ) | 7 | ||||||
| Extensions and discoveries | 46 | 139 | 2 | 72 | ||||||||
| Purchase of reserves | — | 5 | — | 1 | ||||||||
| Production | (16 | ) | (227 | ) | (4 | ) | (58 | ) | ||||
| Sale of reserves | — | — | — | — | ||||||||
| Proved reserves as of December 31, 2007 | 388 | 1,844 | 39 | 734 | ||||||||
|
Proved developed reserves as of: December 31, 2004 |
123 | 2,043 | 43 | 507 | ||||||||
| December 31, 2005 | 103 | 1,708 | 41 | 429 | ||||||||
| December 31, 2006 | 112 | 1,560 | 33 | 405 | ||||||||
| December 31, 2007 | 195 | 1,506 | 30 | 476 | ||||||||
| International (1) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Oil (MMBbls) |
Gas (Bcf) |
Natural Gas Liquids (MMBbls) |
Total (MMBoe) |
|||||||||
| Proved reserves as of December 31, 2004 | 134 | 29 | — | 138 | ||||||||
| Revisions due to prices | (18 | ) | (1 | ) | — | (18 | ) | |||||
| Revisions other than price | 15 | (3 | ) | — | 15 | |||||||
| Extensions and discoveries | 6 | — | — | 5 | ||||||||
| Purchase of reserves | — | — | — | — | ||||||||
| Production | (8 | ) | (3 | ) | — | (8 | ) | |||||
| Sale of reserves | — | — | — | — | ||||||||
| Proved reserves as of December 31, 2005 | 129 | 22 | — | 132 | ||||||||
| Revisions due to prices | (3 | ) | — | — | (2 | ) | ||||||
| Revisions other than price | 5 | (12 | ) | — | 3 | |||||||
| Extensions and discoveries | 14 | (1 | ) | — | 14 | |||||||
| Purchase of reserves | — | — | — | — | ||||||||
| Production | (10 | ) | (1 | ) | — | (10 | ) | |||||
| Sale of reserves | — | — | — | — | ||||||||
| Proved reserves as of December 31, 2006 | 135 | 8 | — | 137 | ||||||||
| Revisions due to prices | (9 | ) | — | — | (10 | ) | ||||||
| Revisions other than price | 12 | — | — | 12 | ||||||||
| Extensions and discoveries | 1 | — | — | 1 | ||||||||
| Purchase of reserves | — | — | — | — | ||||||||
| Production | (20 | ) | (1 | ) | — | (20 | ) | |||||
| Sale of reserves | — | — | — | — | ||||||||
| Proved reserves as of December 31, 2007 | 119 | 7 | — | 120 | ||||||||
| Proved developed reserves as of: December 31, 2004 |
41 | 29 | — | 45 | ||||||||
| December 31, 2005 | 54 | 22 | — | 57 | ||||||||
| December 31, 2006 | 59 | 8 | — | 60 | ||||||||
| December 31, 2007 | 48 | 6 | — | 49 | ||||||||
(1) Included in the International quantities of proved reserves as of December 31, 2007, 2006, 2005 and 2004 are 86 MMBoe, 103 MMBoe, 105 MMBoe and 115 MMBoe, respectively, which are attributable to production sharing contracts with various foreign governments.
Noteworthy amounts included in the categories of proved reserve changes for the years 2007, 2006 and 2005 in the above tables include:
Extensions and Discoveries: 2007 — Of the 315 MMBoe of 2007 extensions and discoveries, 119 MMBoe related to the Barnett Shale area in Texas, 34 MMBoe related to the Carthage area in east Texas, 22 MMBoe related to the Jackfish steamassisted gravity drainage project in Canada, 20 MMBoe related to the Lloydminster heavy oil development in Canada, 17 MMBoe related to the Washakie area in southern Wyoming and 15 MMBoe related to the Woodford Shale in eastern Oklahoma.
The 2007 extensions and discoveries included 154 MMBoe related to additions from Devon's infill drilling activities, including 96 MMBoe related to the Barnett Shale and 19 MMBoe related to Lloydminster.
2006 — Of the 433 MMBoe of 2006 extensions and discoveries, 143 MMBoe related to the Barnett Shale, 88 MMBoe related to Jackfish, 30 MMBoe related to Carthage and 20 MMBoe related to Washakie.
The 2006 extensions and discoveries included 202 MMBoe related to additions from Devon's infill drilling activities, including 127 MMBoe related to the Barnett Shale area and 20 MMBoe related to the Lloydminster area in Canada.
2005 — Of the 399 MMBoe of 2005 extensions and discoveries, 118 MMBoe related to Jackfish, 54 MMBoe related to the Barnett Shale, and 40 MMBoe related to the Deep Basin in Canada.
The 2005 extensions and discoveries included 76 MMBoe related to additions from Devon's infill drilling activities, including 19 MMBoe related to the Barnett Shale, 16 MMBoe related to Carthage and eight MMBoe related to the Permian Basin in New Mexico and west Texas.
Purchase of Reserves: The 2006 total included 100 MMBoe located in the Barnett Shale that was acquired in the June 2006 Chief acquisition.
Sale of Reserves: The 2005 total included 176 MMBoe of reserves related to non-core oil and gas properties in the offshore Gulf of Mexico an onshore in the United States and Canada.
Revisions Other Than Price: The 2007 total included performance revisions of 39 MMBoe in the Barnett Shale, 13 MMBoe at Jackfish, 13 MMBoe in Carthage and 7 MMBoe in China.