CHARACTERISTICS AND MODELS OF HYDROCARBON ACCUMULATION IN XINGLONGTAI OILFIELD, LIAOHE DEPRESSION

The characteristics of hydrocarbon accumulation in Xinglongtai area were studied based on geochemical and geological data. Data shows that the region is characterized by multiple sources, multiple types of conduits and several stages of hydrocarbon charging. Oil-source correlation suggests that the Qingshui sag is the main hydrocarbon generation sag, with the Chenjia sag the next, and the Sha-3 member of the Qingshui sag is also a significant reservoir. Nitrogen compounds indicate that hydrocarbon migrates from the generation sag to the high part of the structure through faults, sands and unconformities. Fluid inclusions and genetic history of source rocks indicate that there are several stages of hydrocarbon accumulation, and the late Oligocene (30.8~24.6 Ma) is the main one. Based on the researches above, three hydrocarbon accumulation models for the Xinglongtai area are established:(1)single source, faults-unconformity conduit, earlier accumulation in buried hill reservoirs; (2)self-source, fault and turbidite sands conduit, earlier accumulation in E₂s₃ turbidite reservoirs; (3)multi-source, fault-sand conduit, later accumulation in E₃s₁₊₂ and E₃d reservoirs.