Study on the accumulation conditions of shale gas from the Lower Paleozoic in the south region of Sichuan Basin.

Based on the data from drilling, core samples, etc., taking the Lower Cambrian Qiongzhusi Formation and the Lower Silurian Longmaxi Formation shales as study target area, authors investigated the accumulation conditions of marine shale gas from the Lower Paleozoic in the south region of Sichuan Basin. The results indicate that the Qiongzhusi Formation and the Longmaxi Formation black shales in this region are mainly formed in shelf sedimentary facies. The study region features great organic-rich shale thickness, high organic abundance (average TOC >2%), Type I and II organic matter, high-over thermal evolution level, rich in brittle mineral, abundant in micro- and nanometer pores, and high gas content, which are in favor of the generation and enrichment of shale gas. Compared with the shales in North America, in which the shale gas has been explored and developed successfully, it is suggested that the Lower Paleozoic in the south region of Sichuan Basin has good accumulation conditions for shale gas. Therefore, the Qiongzhusi and Longmaxi Formations are considered as the practical targets for shale gas exploration, and their favourable areas of shale gas enrichment are also purposed. [ABSTRACT FROM AUTHOR]