沁水盆地南部煤层孔隙-裂隙系统及其对渗透率的贡献

Pore and Fracture Systems and Their Contribution to the Permeability of Coal Reservoirs in Southern Qinshui Basin

基于常规孔渗测试、核磁共振、扫描电镜等分析,研究了沁水盆地南部煤储层孔隙-裂隙系统发育特征及其对渗透率的贡献。结果表明,煤样孔隙结构以吸附孔为主,渗流孔发育相对较差,可动流体孔隙度很小;多数煤样A类和B类较大裂隙所占比例不高,C类和D类较小裂隙较为发育;大孔孔隙度和微裂隙发育程度对渗透率影响最大。但本区煤样大孔孔隙度低,裂隙多被矿物充填,孔隙、裂隙之间连通性较差,对煤储层渗透率的贡献较小;多期发育的宏观构造裂隙可能对煤储层渗透性起到一定的改善作用。

Based on the studies of the conventional porosity and permeability, nuclear magnetic resonance （NMR） and scanning electron microscope （SEM）, pore and fracture system and its permeability contribution of the coal reservoirs in southern Qinshui basin were discussed. Results showed that the pores of coal samples are mainly composed of adsorption pores while seepage pores develop poorly, resulting in a very low porosity for movable fluid. Percentage of large fissures with type A and B is relatively low in most coal samples, while small fissures with type C and D develop well. Macropores and microfissures have commonly with most important contribution to the permeability of coals. The macropore porosity in the samples from the Qinshui basin is relatively low with most of the fissures filled by minerals. The connectivity among the pores and fissures is poor, which decrease the permeability of the coal reservoir in the Qinshui basin in general. Macroscopic tectonic fissures may improve the permeability of the coal reservoirs to a certain extent.