Shale plays push up US gas resource estimate

Reevaluation of shale plays has pushed the Potential Gas Committee’s assessment of the US natural gas resource to its highest level ever.

By OGJ editors
HOUSTON, June 18
-- Reevaluation of shale plays has pushed the Potential Gas Committee’s assessment of the US natural gas resource to its highest level ever.

The PGC, guided by the Potential Gas Agency of the Colorado School of Mines, raised its biennial assessment to 1,836 tcf at yearend 2008 from 1,321 tcf at yearend 2006.

The committee has been reporting resource estimates for 44 years.

The 2008 assessment ascribes 1,673 tcf of gas to traditional reservoirs, up 45% from the 2006 report, and 163 tcf to coalbed methane reservoirs, down 1.9%.

The technically recoverable resource in the new assessment combines with the US Department of Energy’s gas reserves estimate of 238 tcf to project total future supply of 2,074 tcf. That’s 542 tcf above the 2006 total.

“Our knowledge of the geological endowment of technically recoverable gas continues to improve with each assessment,” said John B. Curtis, professor of geology and geological engineering and director of the Potential Gas Agency. “Furthermore, new and advanced exploration, well drilling, and completion technologies are allowing us increasingly better access to domestic gas resources—especially ‘unconventional’ gas—which not all that long ago were considered impractical or uneconomical to pursue.”

Shale gas accounts for 616 tcf of the new estimate of technically recoverable gas.

The richest US resource area remains the Gulf Coast, including the continental shelf and slope and deep water. Next richest is the Rocky Mountain region, followed by the Atlantic and Midcontinent areas. Those areas account for 87% of the resource total.

The largest volumetric and percentage increases over the 2006 report resulted from reassessment of shale plays in the Appalachian, Arkoma, Forth Worth, and Uinta basins and in several basins of the Gulf Coast.

The 2008 assessment of traditional resources includes mean values (not arithmetically additive to subtotals) of 441.4 tcf of probable resources (current fields), 736.9 tcf of possible resources (new fields), and 500.7 tcf of speculative resources (frontiers).

The coalbed gas assessment includes 14.2 tcf of probable, 49.8 tcf of possible, and 98.9 tcf of speculative resources.

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