Characteristics of the mud shale reservoirs of transitional facies: with Qinshui basin as an example

From geochemistry, petrology-physical properties and characteristics of the reservoir space, the shale reservoir characteristics are studied by scanning electron microscope, X ray diffraction, mercury experiment and isothermal adsorption experiment analysis of mud shales from Taiyuan Formation in Qinshui basin. The results show that the shale reservoir of Taiyuan Formation is 50~70 m thick, the favorable reservoir layers are mainly upper Taiyuan Formation, the maximum continuous thickness is 10.7~25.13 m in the study area. Organic matter content is high, ranges from 0.12% to 22.78%, above 2.5% on average. The maturity is high, between 1.72% to 3.6%, belonging to a high-over mature stage. Mineral composition mainly includes quartz, clay minerals and its average content of brittle mineral is between 32.12%~45.25%.The micropores are well developed. The pore structure is mainly microporous, holes and large pore, pore connectivity is good. The shale of Taiyuan Formation in Qinshui basin has the characteristics of moderate buried depth of reservoir, large accumulated shale thickness, high organic carbon content, high brittle mineral, well developed micro fracture, good pore connectivity. The adverse conditions are small monolayer thickness, high clay mineral content and higher maturity.