Demonstration of the enrichment of medium quality gas from gob wells through interactive well operating practices. Final report, June--December, 1995

Methane released to the atmosphere during coal mining operations is believed to contribute to global warming and represents a waste of a valuable energy resource. Commercial production of pipeline-quality gob well methane through wells drilled from the surface into the area above the gob can, if properly implemented, be the most effective means of reducing mine methane emissions. However, much of the gas produced from gob wells is vented because the quality of the gas is highly variable and is often below current natural gas pipeline specifications. Prior to the initiation of field-testing required to further understand the operational criteria for upgrading gob well gas, a preliminary evaluation and assessment was performed. An assessment of the methane gas in-place and producible methane resource at the Jim Walter Resources, Inc. No. 4 and No. 5 Mines established a potential 15-year supply of 60 billion cubic feet of mien methane from gob wells, satisfying the resource criteria for the test site. To understand the effect of operating conditions on gob gas quality, gob wells producing pipeline quality (i.e., < 96% hydrocarbons) gas at this site will be operated over a wide range of suction pressures. Parameters to be determined will include absolute methane quantity and methane concentration produced through the gob wells; working face, tailgate and bleeder entry methane levels in the mine; and the effect on the economics of production of gob wells at various levels of methane quality. Following this, a field demonstration will be initiated at a mine where commercial gob gas production has not been attempted. The guidelines established during the first phase of the project will be used to design the production program. The economic feasibility of various utilization options will also be tested based upon the information gathered during the first phase. 41 refs., 41 figs., 12 tabs