KEY EPISODES OF PETROLEUM MIGRATION AND ACCUMULATION IN THE SOUTHWEST EDGE OF JIANGHAN BASIN

According to analysis of geochemical features of nitrogen compounds in crude oil, petroleum migration direction in the southwest edge of Jianghan Basin is from the main petroleum-generating depression(the Meihuaiqiao Depression) in the north to the Fuxinchang,Caixue Belt in the south.With techniques such as fluid inclusion,laser Raman spectrum and micro-fluorescence analysis,it is studied the episodes of oil pools formation.There are two episodes for petroleum to entrap: the first one is the early period of Jingsha Formation of Lower Tertiary,the second one is the medium-late period of Qianjiang Formation of Lower Tertiary. Three patterns to form oil-pools are put forward: the Inner Source-Nose-Like Fault-Facies-Controlled(self-generated and self-stored),the Inner Source-Nose-Like Fault-Fault-Controlled(generated in the lower section and stored in the upper section) and the Marginal Source-Faulted Block-Fracture and Facies-Controlled.