Impacts of vertical variation of different coal texture types on coalbed methane production in Zaoyuan area of the Shizhuangnan Block, Southern Qinshui Basin, North China

Abstract

ABSTRACTDetermining the causes of gas production difference among wells and regions is crucial for future coalbed methane (CBM) exploration and development. Combined with gas content and equivalent drainage radius (ER), the vertical characteristics that different coal texture types overlaid are researched and compared between the north and south regions in the Zaoyuan area of Shizhuangnan Block, Southern Qinshui Basin. The results indicate that the vertical relationship of different coal textures has a great impact on gas/water production. Thicker granulated coal may contribute to adsorb more gas, but may also increase the possibility of blocking the seepage channel with coal powder in the coals. CBM in granulated coals could flow into the wellbore through the fractures in the upper and lower cataclastic or undeformed coals, and the mudstone contact directly below the granulated coals in the north may restrict gas production, as mudstone could obstruct the seepage passage that CBM in granulated coal flows downward.