Abstract:

Marine strata deposited from the Sinian to the Middle Triassic in Sichuan basin which was important to oil and gas exploration. Mudstone deposited during the Doushantuo stage of Lower Sinian, the Qiongzhusi Formation of Lower Cambrian and the Longmaxi Formation of Lower Silurian. Two types of source rocks deposited within the Qixia Formation of Middle Permian and the Wujiaping Formation of Upper Permian. The distribution characteristics of each stage are studied in detail. According to this study, the main hydrocarbon generating center of Doushantuo Formation locates in the Fuling district, the main hydrocarbon generating center of Qiongzhusi Formation locates in the area from Chengdu to Zigong. There are two main hydrocarbon generating centers which are Wanxian district and Luzhou-Qijiang area during the Longmaxi Formation, three hydrocarbon generating centers during Qixia Formation, and single hydrocarbon generating centers in Wanxian-Wushan district during the Wujiaping Stage. The maturity evolution of source rocks turns to matured or over-matured stage and the hydrocarbon-generating intensity is controlled by the abundance of organic matter and thickness of source rock. The stage of TST within the second-order sequence is better to deposit regional source rock. The types of source rock，organic matter and abundance of organic matter are mainly controlled by the sediment settings, the distribution and the maturity evolution of source rock are mainly affected by the tectonic movement.

Key words: source rock distribution, controlling factors, marine strata, Sichuan basin, petroleum gas