Powder River CBM Estimates Raised, Uinta-Piceance Lowered

The Powder River Basin of the Rocky Mountains holds more coalbed methane (CBM) reserves than previously thought, according to a U.S. Geological Survey (USGS) official, who testified Thursday before the House Energy and Mineral Resources Subcommittee. However, on a less positive note at the oversight hearing on CBM issues, Gene Whitney, a USGS supervisory geologist, lowered the forecast for CBM in the Uinta-Piceance Basin.

The USGS now estimates the Powder River Basin to hold about 14.26 Tcf, substantially higher than its estimate of 1.11 Tcf made six years ago in 1995. The Uinta-Piceance Basin, however, holds only about 2.32 Tcf of undiscovered, technically recoverable CBM, a drop from the agency's first estimate in 1995 of 10.70 Tcf. CBM accounts for about 8% of current U.S. gas reserves and about 7% of gas production, Whitney said.

In the United States, the San Juan Basin has historically been the most productive basin for CBM, with two-thirds of the known reserves and 80% of the production. Behind San Juan, the Warrior Basin in Alabama has brought in 8% of reserves and 9% of output. However, the picture is changing, Whitney said.

With the "emergence of other western U.S. coalbed methane basins," especially Wyoming's Powder River, the United States has experienced a boom in CBM, he said. The coalbeds in the Powder River are up to 300 feet thick but are at shallow depths, which makes the wells inexpensive to drill and operate.

"Exploration and production activity in the Powder River Basin began to increase geometrically once coalbed methane developers understood the production techniques necessary to successfully produce the gas," Whitney testified. About 110 CBM wells in Powder River produced 6.5 MMcf/d and 949,637 gallons a day of water in May 1994. Now, there are 5,446 wells producing 642 MMcf/d and 61.1 million gallons a day of water, he said.

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