The oil and gas system in the reformed basin: a case study of the basin-mountain transitional area on the western side of the Xuefeng Mountain

South China has Sinian-Lower Triassic marine sediments 8000~10000m in thickness and hence has been considered to be one of the main distribution areas of marine carbonate sediments. There are two assemblages of marine petroleum system: one is the lower assemblage consisting mainly of Sinian, Cambrian, Ordovician and Silurian strata, and the other is the upper assemblage comprising primarily Devonian, Carboniferous, Permian and Middle-lower Triassic strata. The western side of the Xuefeng Mountain has developed various degrees of oil and gas bearing layers and petroliferous assemblages. This area also possesses very rich oil and gas resources characterized by complicated trap and preservation conditions as well as oil reservoir evolution processes. Based on a discussion on the methods for studying the reformed petroliferous basin and geological process of the petroleum system, this paper emphatically analyzed the petroleum system in four key hydrocarbon-bearing areas so as to provide the evidence for petroleum survey on the western side of the Xuefeng Mountain as well as for the optimization of the exploration target areas.