低勘探程度盆地成藏动力学过程:以西湖凹陷中部地区为例

基于地质类比方法，综合运用地质、地球物理、地球化学等资料及盆地模拟技术恢复了西湖凹陷中部地区油气成藏动力学过程.结果表明:研究区内沉积充填和构造沉降具有幕式演化特征，并以始新世地层沉积厚度最大、沉积-沉降速率最高；烃源岩有机质热演化具有成熟时间短、生油窗窄、生气窗宽的特点；主力烃源岩平湖组进入成熟生烃门限的时间早，生排烃能力强，且生排烃过程发生在晚渐新世至早-中中新世期间；研究区油气运移和油气聚集主要受控于古构造面，保俶斜坡带和天屏断裂陡坡带以平行流为主，中央背斜带以汇聚流为主，存在多个有利油气聚集区，油气聚集作用主要发生在龙井运动(7 Ma)以来. 

Dynamic Process of Hydrocarbon Accumulation in Low-Exploration Basins: A Case Study of Xihu Depression

This paper re-constructs and analyzes dynamic process of hydrocarbon accumulation in the central part of Xihu depression by using the geological data, geophysical and geochemical techniques of basin modeling in accordance with geological comparison principles. It is found that the depositional filling and tectonic subsidence experienced episodic evolution in study area with its sedimentation thickness and subsidence rate reaching the biggest value in Eocene. The organic matter evolution of source rock is characterized by short maturation, narrow zone of oil generation and broad zone of gas generation. The main source rock of Pinghu Formation reached oil threshold earlier with strong hydrocarbon generation-expulsion capacity, and the generation-expulsion process occurred in early Late Oligocene and Early-Miocene to Mid-Miocene. The petroleum migration and accumulation are controlled by the paleo-structure surface, and the confluence flowing mainly occurs in the Baochu gentle slope zone and Tianping fault steep slope zone while the planar flowing occurs in the central anticline belt. There are several favorable zones of petroleum accumulation in the study area, and the major accumulation of oil and gas occurred over the Longjing movement (7 Ma).