Hydrologic characterization of coal seams for methane recovery. Final report, January 1987-April 1989

Coal seams have unique physical and chemical properties that can make conventional production methods for clastic or carbonate reservoirs ineffective. Some dewatering of most coal seams is needed to allow desorption of methane before production can begin. Theory was developed and a well-testing method incorporating the effects of gas desorption and two-phase flow of water and gas is presented to characterize production properties of a coal seam. A well-testing method incorporating the effects of single-phase flow in a vertical well intercepting more than one coal seam was developed to investigate gas production and economic feasibility of multiple, thin coal horizons. A well-testing method was developed to interpret the geometry, size, and effectiveness of hydraulically created fractures in coal seams, which normally yield complex fractures with vertical and horizontal components. To further enhance the economic potential of a coalbed methane project, personal-computer software was developed to help the operator select a dewatering pump suitable for his particular coal-seam properties and production characteristics.