焦石坝地区五峰组-龙马溪组页岩纹层发育特征及其储集意义

Shale Lamination and Its Influence on Shale Reservoir Quality of Wufeng Formation-Longmaxi Formation in Jiaoshiba Area

目前针对海相富有机质页岩纹层对储层品质的影响方面尚未开展深入研究.通过钻井岩心、薄片鉴定、氩离子抛光扫描电镜、核磁孔隙结构和扫描电镜矿物定量评价(QEMSCAN)等测试分析,将川东焦石坝地区五峰组-龙马溪组一段页岩纹层按矿物组分划分为硅质纹层、钙质纹层和粘土质纹层3类,并识别出水平纹层、杂积纹层、粒序纹层、侵蚀交错纹层和楔状交错纹层5类页岩纹层沉积构造.结合纹层发育密度和最大纹层厚度,划分出3个纹层发育段,每一段又细分为弱发育段和强发育段.综合纹层发育特征和页岩储层物性参数可知:纹层强发育段其总有机碳含量和有机质孔隙均相对减少,而无机质孔隙相对发育,纹层发育影响了页岩孔隙类型和孔径占比的分布.

There is no in-depth study on the impact of marine organic-rich shale lamination on reservoir quality.In this paper,according to lamination mineralogical composition,the shale lamination can be divided into sillceous lamina,calcium lamina and clay lamina through thin section,NMR porosity and QEMSCAN.Besides,horizontal lamina,hybrid lamina,graded lamina,cut-fill cross lamina and wedge-shaped cross lamina are found in Wufeng Formation-Longmaxi Formation marine shale.Combined with the laminae density and maximum thickness of laminae,the interval of interest is divided into three lamination development phases,which are subdivided into weak development stage and strong development stage.Composited with shale lamination characteristics and reservoir characteristics,total organic matter content and organic pores were reduced in shale laminated strong development stage,with enhanced development of inorganic pores.The pore type and pore size distribution is influenced by the laminated development.