Abstract:

Marine hydrocarbon accumulation and evolution in China is characterized by old age and frequent modification,especially by tectonic movements in the later period.Strong heterogeneity is one of the features of marine reservoirs in China.The reservoir spaces of carbonates are dominated by pores,fractures and vugs formed or enhanced by karstification.The existence of favorable primary pores and vugs is one of the conditions for karstifieation.According to the degree of karst development,the karst reservoirs can be divided into four types, including Naxi,Tahe,Renqiu,and Puguang.Hydrocarbon generation and accumulation occurs in multistage and is influenced especially by the neotectonic movement.Several source rocks of different types and of different horizons may have contributed to the reservoirs.Consequently,source control theory,to a certain degree,is not applicable to these reservoirs.It is recommended to divide these reservoirs into primary,quasi-primary,and secondary reservoirs according to the relationship between hydrocarbon reservoirs and source rocks.The preservation conditions are critical to commercial hydrocarbon accumulations.Marine hydrocarbon exploration shall stress the importance of basic studies on petroleum geology and focus on areas with favorable preservation conditions,so as to provide information for exploiting deeper strata under ductile beds.Oil and gas exploration and development shall be carried out simultaneously and more attention shall be given to gas.

Key words: multi-phase hydrocarbon accumulation, pologeneses, evolution and modification of hydrocarbon reservoirs, preservation condition, marine hydrocarbon in China