云南恩洪和老厂地区煤储层孔隙-裂隙系统对比分析

Comparative Analysis of Pore and Fracture System of Coal Reservoirs from Enhong and Laochang Districts, Yunnan

云南恩洪和老厂地区是我国西南潜在的煤层气开发基地。基于相关测试资料和数据,从孔隙-裂隙系统角度分析了两区煤储层的储气能力、渗流能力及其控制因素。结果表明,老厂煤样吸附孔隙结构优于恩洪煤样,但恩洪煤样渗流孔隙结构均质性较好,渗流能力较强;然而,老厂煤样显微裂隙密度相对较高,弥补了其渗流孔隙结构的不足。发现吸附孔隙比例与固定碳、镜质组含量存在线性关系,渗流孔隙比例与挥发分产率、惰质组含量有正相关关系;大-中孔体积对煤岩孔隙度贡献较大,煤样渗透率受到孔隙度和显微裂隙密度的控制。

Enhong and Laoehang districts in Yunnan province are the potential areas of the coalbed methane （CBM） development in the southwest China. Based on the lab data, the adsorption, seepage and geological controls of the coal reservoirs in the districts were discussed in the light of the pore and fracture system. Results showed that the adsorption pore structure of these two Laochang＇s coals is better than that of the Enhong＇s coals but the seepage pore structure of the Enhong＇s coals has a higher homogeneity and seepage capacity than that of the Laochang＇ s coals. However, the higher frequency of the micro-fracture occurrence in the Laochang＇s coals makes up for the defect of seepage pore structure. It was found that the proportion of the adsorption pores has a linear correlation with the fixed carbon content and vitrinite reflectance while the proportion of the seepage pores has a positive correlation with volatile yield and inertinite content. Volume of the seepage pores makes a greater contribute to coal porosity, and the coal permeability is controlled by both the porosity and micro-fracture frequency.