Thermal evolution of Dongpu Sag

The vitrinite reflectivities of the eastern subsag,western subsag and central uplift are higher than those of the Baimiao region and western slope belt on the Carboniferous-Permian upper surface.The palaeo-temperature and present temperature of the eastern and western subsags are close,which means that the two subsags have a great sedimentation since Cainozoic era and the geo-temperature keeps rising.So the Upper Paleozoic source rocks are controlled by present temperature and the area belongs to the area of secondary hydrocarbon generation.According to the relationship between the vitrinite reflectivity and burial depth in the Baimiao region and in the western slope belt,the Neogene system and Eogene system are lack of compensation and the palaeotemperature is higher than the present temperature,which means this area has a great denudation since the Neogene period and the source rocks are controlled by the palaeotemperature,and the area hasn't the process of secondary hydrocarbon generation since the Neogene period.