Seepage channel model and gas–water differentiation of near-vertical coal reservoirs in the Kuba coalfield, China: implication for coalbed methane development

The coal seams in Kuba coalfield are near-vertical distributed, and the composition of the seepage channel and gas–water differentiation is quite different from that of the horizontal coal seam. By using high-precision tectonic fracture mapping technique, fine observation and dissection technique of coal reservoirs in the underground, and microscopic observation, the seepage channel model of near-vertical coal reservoir is established, and the gas–water distribution is researched. The seepage channel is mainly composed of four fractures, that is, tectonic fractures, bedding fractures, cleats, and micro-fractures. Furthermore, the characteristics of the four fractures are studied in detail; the dominant direction of coal reservoir permeability is analyzed. Coal seam water and gas in near-vertical coal reservoir have serious gas–water differentiation. Coal seam water moves to the lower coal and gas to the upper coal due to the influence of gravity. The seepage channel model and gas–water differentiation of near-vertical coal reservoir research the high-permeability area of coalbed methane (CBM) development block from the vertical and horizontal directions, which is of great significance for CBM development.