川南地区龙马溪组页岩岩相对页岩孔隙空间的控制

页岩的孔隙类型、孔隙结构的定量化表征以及孔隙空间的控制因素是页岩储层研究的重要问题。川南地区龙马溪组的页岩岩相按矿物组分可分为硅质页岩、混合质页岩和黏土质页岩。利用扫描电镜矿物定量评价（QEMSCAN）技术、低温N₂和CO₂吸附实验以及高压压汞实验对川南地区龙马溪组不同页岩岩相的孔隙类型、结构特征及孔隙空间的控制因素开展了分析。研究结果表明，黏土质页岩多发育黏土矿物片状粒内孔且多被迁移有机质充填；混合质页岩多发育有机质孔和碳酸盐矿物溶蚀宏孔；硅质页岩多发育有机质孔。页岩的总面孔率主要由孔径为0~500 nm的孔隙提供，矿物（除碳酸盐矿物与长石外）及有机质中的孔隙均以粒内孔为主，有机质的面孔率高达32.37%，为矿物颗粒的8~16倍。页岩的中孔是孔体积的主要贡献者，微孔是孔比表面积的主要贡献者。混合质页岩的总面孔率、孔体积与孔比表面积的平均值与硅质页岩相近，具有良好的储集能力。高TOC含量的混合质页岩与硅质页岩的孔隙空间主要受有机质孔控制，TOC含量较低的黏土质页岩的孔隙空间则主要受有机质孔和伊利石相关孔隙共同控制。

Control of lithofacies on pore space of shale from Longmaxi Formation,southern Sichuan Basin

The pore types of shale, quantitative characterization of pore structures and control factors of pore spaces are important topics in research of shale reservoir. The shale lithofacies of Longmaxi Formation in the southern Sichuan Basin can be classified into siliceous shale, mixed shale and argillaceous shale according to the mineral composition. The pore types, structural characteristics and control factors of pore spaces of different shale lithofacies of Longmaxi Formation in the southern Sichuan Basin were analyzed by technologies of quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN), low temperature N₂ and CO₂ adsorption and high pressure mercury intrusion experiments. The results show that the argillaceous shale is mostly characterized by the sheet-like intragranular pores of clay minerals and filled with the migrated organic matters; the mixed shale is rich in organic matter pores and carbonate dissolved macropores; siliceous shale is rich in organic matter pores. The total surface porosities of shale is mainly provided by the pores with the diameter of 0-500 nm. The surface porosity of minerals (except carbonate and feldspar)and organic matters are mainly contributed by intragranular pores. The surface porosity of organic matter is up to 32.37%, 8 to 16 times higher than that of mineral particles. The mesopores of shale are the main contributors to the pore volume, while micropores make a major contribution to the specific surface area of pores. The average surface porosity, pore volume and pore specific surface area of mixed shale are similar to those of siliceous shale, which means the mixed shale has potential storage capacity. The pore space of mixed shale and siliceous shale with high TOC content is mainly controlled by organic matter pores, but the pore space of argillaceous shale with lower TOC content is mainly controlled by organic matter pores and illite mineral related pores.