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目前对优势页岩岩相的划分尚缺乏明确的标准.另外,合理连接不同孔隙测试方法的结果,实现页岩的全孔径孔隙结构定量化表征,成为现阶段亟待解决的关键问题.基于页岩的有机质丰度和矿物组分建立了岩相划分方案,查明了渝东南下志留统龙马溪组页岩发育硅质页岩、混合质页岩和粘土质页岩3类,根据有机质丰度将每类页岩细分为富、含和贫有机质等共计9种岩相,在此基础上开展了低压N2吸附和高压压汞实验.研究区龙马溪组中富有机质页岩孔径呈现多峰分布特征,主要孔径峰值位于2~3nm、70~90nm和200~300nm,页岩的孔体积主要来源于中孔(2~50nm)和宏孔(>50nm),比表面积主要来自中孔和微孔(<2nm);对于孔体积贡献,微孔最高可占12%,中孔占53%,宏孔占52%.对于孔面积贡献,微孔最高占47%,中孔占57%,宏孔占11%.随着粘土矿物含量升高,在200~400nm范围内孔体积显著升高.中孔和宏孔贡献了超过90%的孔体积,微孔和中孔贡献了超过90%的比表面积.富有机质硅质页岩微孔比例高,对比表面积贡献高,孔体积和比表面积最大,有利于页岩气富集,是最有利的页岩岩相.
At present, there is still no clear standard for the division of dominant shale facies.In addition, it is a key issue urgently needed to solve the problem of rational connection of the results of different pore testing methods and the realization of quantitatively characterizing the full aperture pore structure of shale. The organic matter abundance and mineral composition of the lithofacies subdivision scheme was established. It was found that the Silurian shale, mixed shale and clay shale in the Lower Silurian Longmaxi Formation in the southeastern part of Shandong Province are classified into three types. According to the abundance of organic matter This paper classifies each type of shale into nine facies including rich, poor and poor organic matter, on the basis of which, low-pressure N2 adsorption and high-pressure mercury intrusion experiments were carried out.Moreover, The pore size of shale mainly comes from mesopores (2 ~ 50nm) and macropores (> 50nm). The specific surface area mainly comes from mesopores and micropores (<2 nm). For the pore volume contribution, the micropores can account for up to 12%, mesopores 53%, macropores 52%, micropores up to 47%, mesopores 57%, macropores Accounting for 11% .With the increase of clay mineral content, the pore volume increased significantly in the range of 200-400 nm. Contributed more than 90% of the pore volume, with micropores and mesopores contributing more than 90% of the specific surface area.The high ratio of micropores to organic-rich siliceous shale contributes to the high specific surface area and the largest pore volume and specific surface area, favoring shale Gas enrichment is the most favorable shale facies.