Santanghu Basin is a typical reworked superimposed basin in western China. The volcanic hydrocarbon accumulations mainly distributed at Carboniferous and Permian. Based on tectonic evolution history and hydrocarbon generation history, it analyses the volcanic accumulation process in Carboniferous and Permian formations of Santanghu Basin. The Hercynian Indo- Chinese epoch, when Late Permian to Triassic, and Yanshan epoch, when Late Jurassic to Cretaceous are the two main volcanic accumulation periods. The accumulation formation and later adjustment are closely related to tectonic movements. The accumulation model can be summarized as：Permian and Carboniferous volcanic weathering crust under the unconformity surface were the favorable reservoir, which was rich in corroded pore and fissures, the main storage space. Lacustrine mudstone under the reservoirs are the source rocks. Under the tectonic background, hydrocarbon migrated through weathering crust and fissures, then accumulated to the favorable trap which usually under the unconformity surface. We called it the stratigraphic hydrocarbon accumulation model. The accumulation process analysis is useful for reference to the petroleum exploration in lower assemblage of the western basins in China.
