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Coalbed reservoir permeability is primarily controlled by cleats and fractures in the coal. Because coalbeds are often saturated with brine, the simultaneous flow of gas and water occurs. A formal program of experimental and numerical research is underway to investigate the effect of cleat void geometry on multiphase flow through coal. Sample preparation techniques were developed for preparing coal drill cores for gas flow experiments and metal injection experiments. A Wood's metal porosimetry system was designed and built that consists of a hydrostatic pressure vessel, pore fluid system, and a data acquisition system. The feasibility of using Wood's metal porosimetry on coal was demonstrated. Data on effective cleat porosity, cleat aperture, spatial distribution of apertures, cleat density and cleat spacing were obtained. A stratified continuum model was used to generate cleat void simulations for modeling two-phase flow in a cleat. Two-phase flow modeling is based on capillary pressure effects alone and examines the effect of trapping water in a cleat on the capillary pressure-saturation relationship.
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