东海西湖凹陷成藏流体历史分析

应用含油气盆地数值模拟技术和储层烃类成藏化石记录资料，分析了东海陆架盆地西湖凹陷的成藏流体历史，有关认识可为研究区的油气成藏动力学研究和勘探评价提供重要参数。生排烃史模拟和构造运动特征分析表明，始新统平湖组烃源岩的生、排烃强度高，是西湖凹陷最重要的生排烃层系，其于早中新世进入成熟，于中中新世达到生排烃高峰，现今处于高成熟阶段；发生于中新世末的龙井运动是西湖凹陷油气运聚最重要的时期，是凹陷油气系统形成的关键时刻。储层流体包裹体资料揭示，西湖凹陷平湖油气田存在着2期油气充注。其中第一期发生于中中新世，主要以液态烃充注于始新统平湖组中段、上段和渐新统花港组储层之中；第二期发生在中新世末-现今，主要表现为气态烃充注于始新统平湖组储层内。

FLUID HISTORY ANALYSIS IN THE XIHU DEPRESSION, EAST CHINA SEA

The fluid history of hydrocarbon accumulation in the Xihu depression of the East China Sea continental shelf basin, which can provide some important parameters to the research of hydrocarbon accumulation dynamics and prospect evaluation, has been analyzed by using the technique of petroliferous basin numerical modeling and the data of fossil record of hydrocarbon migration and accumulation in reservoir rock in this paper. The modeling of hydrocarbon generation and expulsion histories and the analysis of tectonic uplift event show that the Eocene Pinghu Formation is the most important source rock due to its great intensities of hydrocarbon generation and expulsion; the source rock in the Pinghu Formation entered the oil window during the Early Miocene, peaked hydrocarbon generation and expulsion during the Middle Miocene, and is presently at the highly-mature stage; the Longjing uplift event at the end of the Miocene is the most important period to hydrocarbon migration and accumulation, and is also the critical moment to petroleum system formation in the Xihu depression. The fluid inclusion data in reservoir rock indicate that the Pinghu Oilfield in the Xihu depression underwent two periods of hydrocarbon charging. The first period occurred the Middle Miocene, and charged mainly liquid hydrocarbon to the Upper and Middle members of the Eocene Pinghu Formation and the Oligocene Huagang Formation, while the second period presented from the end of the Miocene to present-day, and filled dominantly gaseous hydrocarbon to the Eocene Pinghu Formation.