沁南东区块3^#煤层构造煤发育对渗透率的影响

Characteristics of Tectonic Coal in 3~# Coal Seam of Eastern Qinnan Block and Its Influence on Permeability

以沁南东区块3#煤层为研究对象,基于煤层气井钻井取心描述结果,获得构造煤垂向与平面分布特征,阐述了构造煤发育特征对煤层渗透率的影响。结果表明:平面上,构造煤主要沿断层发育,距离断层越近构造煤发育程度越高,原生结构煤主要发育于两断层条带之间距离断层相对较远的区域;垂向上,碎粒结构煤和糜棱煤靠近煤层直接顶底板发育,而碎裂结构煤多位于煤层中部。沁南东区块3#煤层西北部、中部和南部渗透率明显较高,并向西南、东南和东北方向递减。原生结构煤和碎裂结构煤共同影响了3~#煤层渗透率,二者处于弹性、弹塑性应变阶段,割理、裂隙的发育程度较高,有利于提高煤层渗透率。

Taking 3~# coal seam of eastern Qinnan block as the research object, based on the description results of CBM well drilling coring, the vertical characteristics and horizontal distribution of tectonic coal were studied, the influence of tectonic coal on permeability was further analyzed. The results show that at horizontal direction, the tectonic coal develops along faults, and more developed closer to the fault. The primary structure coal develops between two fault bands, and is relatively far away from the fault. At vertical direction, the fragmented coal and mylonitic coal develop near the direct roof and floor of the coal seam, while the cataclastic coal is mostly located in the central of the coal seam. The permeability of 3~# coal seam is obviously higher in the northwest, middle and south of the research area, and decreases to the southwest, southeast and northeast. The primary structure coal and the cataclastic coal together affect the permeability of 3~# coal seam in the research area. They are in the elastic and elastic-plastic strain stages which promote the development of cleats and fractures in coal seam. That is the main reason for the high permeability of coal seam in the region primary structure coal and the cataclastic coal developed.