四川盆地焦石坝地区龙马溪组海相页岩储层非均质性特征

以四川盆地焦石坝地区下志留统龙马溪组海相页岩为研究对象，综合利用全岩X衍射、薄片鉴定、阴极发光、氩离子抛光扫描电镜、高压压汞-气体吸附联测、核磁孔隙度等实验数据，开展不同岩相储层特征差异性研究。研究结果揭示:（1）焦石坝地区龙马溪组海相页岩岩相主要分为硅质类页岩、混合类页岩和黏土类页岩；（2）硅质类页岩有机孔隙非常发育，混合类页岩和黏土类页岩中无机孔隙较为发育，其中黏土类页岩有机孔隙发育程度较弱；（3）不同页岩岩相非均质性特征显著。总有机碳含量、孔隙度、孔隙体积、比表面积和含气量方面，硅质类页岩最为发育，黏土类页岩发育程度最低，混合类页岩介于两者之间；（4）硅质类页岩沉积期古生物繁盛有利于有机质富集和有机质孔隙发育，混合类页岩和黏土类页岩分别受底流和陆源碎屑沉积作用影响，总有机碳含量较低且有机质孔隙相对欠发育。 

Differential pore development characteristics in various shale lithofacies of Longmaxi Formation in Jiaoshiba area,Sichuan Basin

It is of great significance for shale gas exploration and development to understand different pore characteristics in various shale lithofacies. In this paper, the reservoir characteristics of different shale lithofacies of Longmaxi Formation in the Jiaoshiba area were studied by using X-ray diffraction, thin section analysis, cathodoluminescence, FE-SEM, high pressure mercury intrusion-gas adsorption joint test, and nuclear magnetic resonance porosity. Four preliminary conclusions were obtained:(1) Three main types of shale lithofacies were identified in the Longmaxi Formation in the Jiaoshiba area, including siliceous shale, mixed shale and argillaceous shale. (2) Organic porosity developed well in the siliceous shale, but did not develop in the mixed shale and argillaceous shale, in which inorganic pores were more developed. (3) The reservoir heterogeneity characteristics of various shale lithofacies were remarkable. The siliceous shale was the most outstanding in TOC content, porosity, pore volume, specific surface area and gas content, while the mixed shale the second, and the argillaceous shale the least. (4) When the siliceous shale was deposited, bioproductivity was high, which was conducive to the enrichment of organic matter and the development of organic porosity. The mixed shale and argillaceous shale controlled by deep-water currents and terrigenous clastic material supply showed low TOC contents and poor organic pore development.