COALBED METHANE DEVELOPMENT IN THE POWDER RIVER BASIN, WYOMING

Coalbed Methane Development in the Powder River Basin, Wyoming

The Powder River Basin is a 22,000 square mile, asymmetric to the west, structural basin in northeast Wyoming and Southeast Montana. Phanerozoic rocks are as much as 21,000 feet thick. About 75 percent of the basin is in Wyoming. The Powder River Basin is estimated to contain more than one trillion tons of coal, plus extensive deposits of oil, natural gas, and uranium.

The first significant coalbed methane (CBM) was produced in 1987. From June 1993 through March 2001 the nominal, annual CBM production incline rate was 72 percent. During March 2001, 5063 CBM wells produced 608 million cubic feet of gas and 1.39 million barrels of water per day. In addition, at least 2366 additional wells were shut in. Most were waiting on a pipeline connection or water discharge permit.

CBM development progressed rapidly from the shallow eastern part of the CBM play westward. Well depths range from 100 feet to 2100 feet with an average depth of 767 feet. Well spacing is generally 80 acres per well. Individual coalbed thicknesses vary widely but average about 63 feet. Almost all the CBM production is from the Wyoming portion of the Powder River Basin. Currently the CBM play in the Powder River Basin, Wyoming is the most active natural gas play in the country.

The Wyoming portion of the Powder River Basin has a complex pattern of federal, fee, and state mineral ownership. Because of a delay in permitting federal CBM wells and the diverse mineral ownership pattern, extensive drainage of CBM from federal lands has occurred.

The Potential Gas Committee estimates recoverable CBM resources are 24 trillion cubic feet. Cumulative CBM production through March 2001 is 0.36 trillion cubic feet. The Powder River Basin CBM play appears to be a emerging giant.