Review of hydrologic testing in coal beds. Topical report, January 1985-December 1986

Proper design of coal-bed methane production wells depends on knowledge of the target seam's hydrologic properties. Since conventional testing procedures to determine these properties are largely untried on coal seams, the goal of this research was to select coal-bed methane projects where field hydrologic tests have been conducted and evaluate their effectiveness. Specific hydrologic test procedures suitable for characterizing the unique reservoir properties of coal-beds are shown to provide the detailed characterization necessary to meet the initial objectives of GRI's two major field-based projects, the Deep Coal Seam Project and the Multiple Coal Seam Project. The report discusses the multiple-well interference test used to determine porosity-compressibility product and directional permeability properties of the target seams at Rock Creek, Alabama, and other single-well test methods to determine gas desorption pressure, hydraulic-fracture characteristics, and porosity-compressibility product in low-permeability formations. The slug test, in particular, is shown to be a versatile and reliable way to obtain basic coal-seam hydrologic information.