煤层气储层压力是煤层能量的具体表现形式之一,也是煤层气运移、产出的动力,它不仅影响煤层的含气量、煤层气的赋存状态,也影响着煤层的渗透性,从而制约着煤层气的开发。根据9口煤层气参数和试验井的试井资料,结合煤田勘探阶段的钻孔抽水试验资料,对河南省煤储层压力特征进行了系统研究。结果表明,河南省煤层气储层压力变化较大,从欠压到高压均有分布。储层压力是由地下水补给、运移和滞留造成的。在地下水径流区常形成欠压,在弱径流区和滞留区一般形成常压和高压。地下水作用下的煤层气运移不仅从地下水动力条件得到证实,而且从煤层气的成分和成因角度也得到验证。这种压力的形成机制与国内外商业化开发煤层气藏类似,异常高压区是煤层气富集和开发的有利区域。
Coalbed methane(CBM) reservoir pressure is one of the specific forms of the coal seam energy and the force for CBM migration and production. It affects not only the gas content and occurrence, but also the permeability of coal, thereby constraining CBM development. Based on well testing data of 9 CBM pilot wells, and combined with borehole pumping test data in the stage of coal exploration, the reservoir pressure characteristics in Henan have been systematically descripbed. The results indicated that CBM reservoir pressure varied in a wide range, from under pressure to over pressure. The reservoir pressure is caused by recharge, migration, and stagnation of groundwater. The under pressure is commonly formed in the runoff zone, and the normal pressure and over pressure in the weak runoff zone and the deep stagnant zone. CBM migration with groundwater has not only been proved by hydrodynamics, but also verified from the gas composition and genesis. The formation mechanism of this kind of reservoir pressure is similar to commercial development CBM reservoir under commercial development at home and abroad. The abnormal high pressure area is CBM-enriched and favorable development area.