Controlling factor analysis of Paleogene hydrocarbon accumulation of AB sag in Zhujiangkou basin

Paleogene Wenchang-Enping formation is the important horizons for hydrocarbon exploration of Zhujiangkou basin.The research on the distribution of source rocks,tectonic activity strength,pathway systems types,reservoircover conditions and trap types has been carried out.The results indicate the hydrocarbon enrichment degree is controlled by source rocks distribution,the hydrocarbon accumulation capacity is constrained by tectonic activity and pathway systems.The accumulation conditions have the impact on the size of oil and gas reserves and the traps development determines the preservation result.At 40~15 Ma period,a large amount of hydrocarbon has been generated,being of the condition of early oil and gas reservoir.Dongsha movement which began in the Middle Miocene makes the early formed hydrocarbon reservoirs from Wenchang- Enping change,and forms the hydrocarbon reservoirs at late period.At the late middle Miocene,SQ7 sequence of Enping formation started to generate hydrocarbon,which was good for late hydrocarbon accumulation.Therefore,the hydrocarbon accumulation pattern of Wenchang-Enping formation can be divided into three kinds:the early hydrocarbon accumulation pattern,early accumulation-late advanced supplementary pattern and late hydrocarbon accumulation pattern.