河东煤田煤储层中气胀节理的发现及其研究意义

DISCOVERY AND SIGNIFICANCE OF GAS_EXPANDING JOINTS IN COAL RESERVOIR, HEDONG COALFIELD

在山西河东煤田石炭、二叠纪煤储层中发现规模类似于传统外生节理，而产状、节理面特征及发育载体等其他特征与内生裂隙极为相似的两组节理．该节理面上无擦痕和镜面特征，节理面产状与围岩中的节理差异明显．该节理属煤储层中流体间歇性释放造成的纯张节理．该区煤储层岩石物理研究表明，凡发育该类节理的煤储层，其渗透率较高，煤储层可改造性较好．该类节理发育的基本条件是：围岩封闭条件良好、煤储层中有机质丰度高达９０％以上和具有相应温压的煤层气藏成藏条件．研究该类节理不仅可以丰富煤储层岩石物理的研究内容，深化煤层气藏形成与保存条件的认识，而且还有助于正确评价煤层气的可采性．

The authors discover, in the Carboniferous-Permian coal reservoir in Hedong coalfield, Shanxi Province, two groups of joints similar to the traditional exo_joints in scale and to the cleat in occurrence, joint feature, growth carrier and other features. This joint plane is free of scratches and mirror features. The joint plane occurrence is quite different from that of the joint in the wall rocks. This kind of joint is a purely tensional joint caused by the intermittent release of the fluid in the coal reservoir. The physical research into the rocks in this coal reservoir indicates that the coal reservoir containing this kind of joint is characterized by the relatively high permeability. In this sense, the coal reservoir can be restructured. The basic conditions for the growth of this kind of joint are listed as below: sound wall_rock trap, over 90% of organic abundance in the coal reservoir and corresponding temperature and pressure appropriate for the formation of coalbed methane pool. The research into this kind of joint not only adds more references to the investigation into the petrophysics in the coal reservoir, and deepens our understanding of the formation and preservation of coalbed methane pool, but also aids us in the correct evaluation of the extractability of the coalbed methane.