Favorable targets of breakthrough and built-up of shale gas in continental facies in Lower Jurassic, Sichuan Basin

Compared with the successful exploration of shale gas in the North America, the shale gas in the main hydrocarbon-bearing basins in our country is hosted in continental deposition. The mineral composition and sedimentary structure of shale are different between continental and marine facies. The characteristics of fracturing related to rock mechanics are the keys for the effective development of continental shale gas. The shale gas in continental facies mainly develops in mud-shale stones of lacustrine facies in the Lower Jurassic, the Sichuan Basin. Through a lot of old wells reviewed and reevaluated, we have acquired industrial shale gas in Jiannan and Yuanba areas in the east of Sichuan, showing a good potential. The controlling factors for the generation and accumulation of shale gas in the Lower Jurassic of the Sichuan Basin have been analyzed, indicating that the lacustrine facies mud-shale stones are widespread in the Lower Jurassic and are outstanding for in-situ creation and in-situ accumulation. The TOC of mud-shale stones, the thickness of entrapped hydrocarbon and favorable preservation conditions all control the accumulation of shale gas in the Lower Jurassic. The contents of brittle mineral provide good conditions for massive hydraulic fracturing. Reasonable extract mode is the key to acquire industrial and long-term productions. According to shale gas evaluation and fracturing test, the shale gas in the Lower Jurassic of the Sichuan Basin is a favorable target for the breakthrough and built-up of shale gas in continental facies.