COALBED METHANE STUDIES ON FEDERAL LANDS IN THE POWDER RIVER BASIN AND OTHER AREAS IN WYOMING

Production of coalbed methane (CBM) in the Powder River Basin (PRB), Wyoming, has tripled over the past three years. To date, of the 16,000 CBM wells permitted to drill, about 3,500 wells are on federal lands. The U.S. Geological Survey (USGS) is cooperating with the Bureau of Land Management (BLM), Wyoming State Office Reservoir Management Group on several scientific studies in the PRB including: (1) developing methodologies for determining in-place gas content of Fort Union coal beds in order to make reliable estimates of in-place CBM resources; (2) establishing models explaining origin, variability, and distribution of biogenic gas in low-rank coal beds; (3) analyzing the variations in co-produced waters; and (4) determining if CBM wells on State and private lands drain gas from Federal lands. To make reliable in-place CBM estimates, and explain the variability and distribution of biogenic gas in low-rank coal beds, the USGS and BLM have collected 1400 ft of core samples from 10 coal beds in 23 wells. More than 700 canister samples have been desorbed to determine gas content. Thirty-six high pressure adsorption analyses have been completed and selected gas samples have been analyzed for chemical and isotopic composition. In addition, 75 co-produced water and 46 gas samples were collected from production wells to determine their chemical and isotopic composition.

In recent months, CBM exploration and development has begun expanding to other parts of Wyoming, particularly in the Rawlins BLM Field Office area. In addition to the PRB, USGS is assisting BLM with coal-core collection and analysis across the State as needs arise.