Evaluation Of Reservoir Characters Of Long Maxi Formation Of The Lower Silurian In Zhaojue-yongshan Area (Sichuan-yunnan Province)

This article based on the previous researches, synthesized sedimentary petrology, lithofacies paleogeography, petroleum geology, organic geochemistry, statistics and other knowledge of disciplines, combined with the field measured sections, scanning electron microscopy(SEM), organic geochemistry, reservoir physics experiment data, research on the investigation area of Longmaxi shale distribution and sedimentary facies, petrology, organic geochemical characteristics and reservoir physics experiment data, and the analysis and compare the parameters of domestic and foreign shale gas reservoir, by using gray correlation analysis method to evaluate, compare and analysis the shale reservoir characteristics in this investigation area quantitatively and comprehensively.Through the analysis of core observation, logging data and organic geochemical characteristics show that the sedimentary facies of Longmaxi formation in investigated area are mainly shallow shelf facies and deep shelf facies. The effective shale is thick and stable distribution, organic rich shale thickness range from 14 to 138 meters. Total organic carbon content is high, all the sections` average organic carbon content could reach 2.2% and the type of organic matter are mainly type ?1 and type ?, sapropel type kerogen dominated. Organic matter maturity is comparatively high and all at high mature and over mature stage.The mineral composition of Longmaxi shale are mainly clay minerals and quartz, feldspar and carbonate rock take the second place, there is only a small amount of pyrite. The content of clay minerals distributed in 9% ~ 54%, its average content is 29%. Brittle mineral content range from 52% ~ 91%, with an average of 74.9%; it is worth mentioning that the high carbonate rocks` content of brittle minerals in investigate area, its content can come up to 35% on average. The nano pore types of shale samples are mainly microscopic dissolution pores, organic matter pores and micro cracks, porosity distribution range from 0.59% to 1.83%, with an average of 1.31%. The porosity is smaller, permeability of 0.01 m D to 0.0567 m D, the average is 0.0176 m D. The overall properties and permeability are very poor in Longmaxi shale reservoir.According to the Longmaxi group organic-rich shale`s thickness, organic carbon content, maturity of organic matter, porosity, permeability, isothermal adsorption parameters and other facts, Zhaojue-Yongshan area Longmaxi group shale reservoir layer characteristics were evaluated. This paper takes the dissolution pores, pores in organic matter and intergranular pores and fractures as the main reservoir space of Longmaxi formation shale. With strong hydrocarbon generation ability and high organic matter maturity, it is able to form favorable shale gas reservoirs. In the Middle East investigate area, Mabian area is favorable place of preservation condition with less influence of fault. It is found that Longmaxi formation shale of the investigate area has good reservoir characteristics and potential resources by quantitatively comprehensive shale gas reservoir characteristics evaluation based on the grey relational analysis method, and by domestic and overseas major basin analysis and comparison.