川东南彭水地区龙马溪组页岩孔隙结构特征

以单井分析评价为基础,运用氩离子抛光—扫描电镜对川东南彭水地区龙马溪组页岩的孔隙类型进行研究,将研究区层段页岩孔隙分为六大类(包括微裂缝、粒间孔、晶间孔、粒内孔、有机质孔隙和生物化石内孔隙);孔径大小及分布用液氮吸附法及高压压汞法测定,并对两种方法测得的孔径分布结果进行归一化,得到了目的层段页岩孔径的连续分布情况:2~10nm范围内的介孔最为发育。对脆性矿物含量、黏土矿物含量、有机质丰度和类型、成岩作用以及保存条件等5类影响研究区龙马溪组页岩孔隙结构的因素进行了探讨,分析结果显示有机质丰度为彭水地区龙马溪组页岩孔隙结构的主导内在因素。

Shale Porous Structural Characteristics of Longmaxi Formation in Pengshui Area of Southeast Sichuan Basin

Based on the single-well analysis and appraisal, the Ar-ion milling/SEM technology is used to study the porous type of Longmaxi Formation in Pengshui area of southeastern Siehuan Basin. The pores of shale in the study block are divided into six types （including micro- fractures, intergranular pores, intercrystalline pores, intragranular pores, organic matter pores and biological fossil inner pores）. The nitrogen adsorption and mercury intrusion methods are used to inspect pore sizes and its distribution. Distribution of pore sizes is normalized to obtain the continuous distribution of shale pores of the target formation. Namely the pores of 2 to 10nm size developed most. The five influencing factors of shale pore structure of Longmaxi Formation in the study block is brought under analysis and discussion - content of brittle minerals, content of clay minerals, TOC, diagenesis, and conservation conditions. The results of analysis show that TOC is the dominant intrinsic factor of the shale pore structure of Longmaxi Formation in Pengshui area.