| Correlation analysis of geochemical characteristics of isoprenoid in crude oil from Chengbei Fault-step Belt in Dagang Oil Field shows two directions of hydrocarbon migration,one is from the hydrocarbon-generating depression (Qikou Depression) in the north to the Chengbei Fault-step Felt in the south, and the other is from the hydrocarbon-generating depression (Qinan Depression) in the west to the Zhangdong,Guanjiaobao and Chenghai areas in the northeast/east. With methods of the fluid inclusion, the generation and discharge of hydrocarbon and the saturation pressure,two periods of hydrocarbon emplacement are obtained. The first was at the end of Lower Tertiary Dongying Formation and the second is at the end of Upper Tertiary Minghuazhen Formation to Quarter nary. Four models of hydrocarbon accumulation are proposed: the model of lateral migration and accumulation through connecting sand bodies-unconformities,the model of vertical migration and accumulation through faults,the model of stepping migration and accumulation through connecting sand bodies-unconformities-faults, and the model of migration and accumulation in sandstone lens within source rocks. |
