| The study on mineral composition, organic geochemistry, physical property of siliceous shale of Permian Wujiaping Formation were conducted by thin section, X-ray diffraction, organic petrology, low-pressure N2 adsorption, gas intrusion, and scanning electron microscopy combined with argon ion polishing. This shale has a high TOC content (3.07%-11.29%), and moderate maturity of organic matter(1.91%-1.96%), and kerogen type Ⅱ, in which the carbon isotope of kerogen ranges from -27.4‰ to -26.5‰. On organic petrology features the organic matter is mainly composed of sapropelinite and solid bitumen. It is mainly composed of quartz, ranging from 57% to 93%, followed by clay, feldspar, and few carbonate and pyrite. There are mainly organic pores, followed by the intergranular pores in framboidal pyrites, and the pores along the edge of quartz grains, and the poorly developed dissolution pores and microfractures. The specific surface area and pore volume are in the range of 6.63-33.12 m2/g and 0.015-0.047 mL/g respectively, which have a good positive correlation with TOC and have a weak negative correlation with the contents of feldspar and clay minerals. The porosity(2.81%-17.40%) has a good positive correlation with the content of quartz. Similar to Longmaxi shale in Fuling area(Jiaoshiba shale gas field) in Sichuan Basin, it is suggested that there has a very good condition of shale gas formation in Wujiaping siliceous shale. |
