Shale gas accumulation conditions in Daanzhai Member of lower Jurassic Ziliujing Foramtion in the northwest of Sichuan Basin

Abstract: Based on core observation, scanning electron microscope and analysis of geochemical parameters, the authors studied the reservoir-forming conditions such as sedimentary faces, thickness and distribution, organic types and content, maturity and hydrocarbon generation history of the shale in the northwest of Sichuan Basin. Compared with the gas-producing shale in the USA, the study area has developed tidal flat, swamp and lagoon facies, lithology is mainly characterized by shale mud with rich organic matter and large thickness in a single formation, TOC is 2.0% and organic matter is mainly of Ⅲ type with great hydrocarbon generation potential and high thermal evolution. All these factors are favorable for the formation of shale gas reservoir. An analysis of many factors of shale gas accumulation show that Yuanba- southern Yilong and Dazhou-Xuanhan areas have good accumulation conditions for shale gas, and hence are favorable areas for shale gas exploration and development in Daanzhai Member of Jurassic Ziliujing Formation in the northwest of Sichuan Basin.