Discussion on Sedimentary Facies and Hydrocarbon Accumulation Conditions of Paleocene in Yingcuixuan Area, Xihu Sag

The Paleocene in Yingcuixuan area of northern Baochu Slope will become a new field of deep exploration in Xihu Sag of East China Sea shelf basin. Due to the lack of drilling data, the authors infer the sedimentary environment and facies zones in Paleocene period based on the study of seismic data, relationship of sedimentary facies and tectonic setting, as well as the data of redeposited fossil communities. Three dominant facies zones are recognized and they are: (1) the alluvial fans along uplift front; (2) the incised valley facies zones; (3) the offshore shoal facies zone. Then the authors discuss the source rocks, the hydrocarbon generating window and trap conditions in the Paleocene plays. Meanwhile, two unfavorable factors i.e. the high risk of lateral sealing ability in the high part of the fault terrace and the match of fault activity period with hydrocarbon migration are pointed out. Taking into consideration of both the favorable and unfavorable factors, the authors summarize the reservoir forming conditions in the Paleocene plays in the study area and propose the exploration direction.