Reservoir Characteristics Research Of The Lower Longmaxi Formation Shale In East Of Sichuan

This dissertation selects the Lower Silurian Longmaxi Formation(lowersegment black shale) as the main object in the Southern Basin.Combining the fieldinvestigation、sampling and laboratory testing research to study the Shale petrology、diagenesis、Pore characteristics and evolution of the lower Longmaxi Formation.Studies have shown that:Main clay minerals are illite and chlorite, the average content of34%and24%,Brittle minerals are mainly quartz and feldspar、carbonate minerals, The rest iskaolinite3.4%, feldspar6.3%, illite and smectite mixed layer6.7%, smectite1.7%.The content of clay minerals in the longitudinal direction are basically stable. averagevalue:quartz18.3%, well seen carbonation, calcite0.88%, dolomite0.88%, pyrite1.7%.Quartz、 mica take the form of powder sand-size particles in the blackshale.Calcite are veined and dispersion-like distribution. The clay minerals showuniform distribution,illite has obvious directionality.Black shale show a highabundance of organic carbon content in the range of0.75-1.36%with an average of1.04%, the organic carbon content is reduced at vetical.Organic matter type is "I", vitrinite reflectance of2.81-3.11%. The thermalevolution of organic matter has reached a high-over mature stage. Pore types aremainly intergranular pores, intragranular hole, intergranular hole, microporous inlayer, framboidal pyrite hole, hole of organic matter. Overall pore size distributioncharacteristics, it shows that a high proportion of macroporous and microporous poretype is the most important. Porosity range of0.69-2.57%, bottom-up shows adecreasing trend. Pore roar is smaller, micro-little porous show a maximum amount ofmercy injection, mercury capillary pressure curve is steep, the displacement pressureless than0.1MPa.The black shale in the study area has experienced the change of diagenesis suchas compaction, recrystallization and clay mineral transformation and so on,finally theblack shale in the diagenetic late-nearly metamorphism stage. Influence factors ofLongmaxi black shale is pore characteristic、Shale mineral composition、diagenesis、organic content etc.