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为系统认识西湖凹陷浙东中央背斜带的油气分布规律,优化勘探目标选择,推进油气勘探与开发进程,应用含油气系统理论和量模拟技术,对组成浙东中央背斜带油气系统的基本地质要素与成藏作用过程进行了综合分析。研究表明,始新统平湖组泥岩与煤层为该区主力烃源岩,具较高有机质丰度与生、排烃强度;浙新统花洪组砂质岩是最重要的储集岩;花港组上段泥岩为区域性盖层;圈闭发育与油气生、排、运聚的配置关系良好,是烃类聚集的理想场所;该区存在４个含油气系统,多属天然气系统,其中中平湖组一花港组系统为最主要的含油气系统,其油气生成聚集效率高,是本区目前主要的油气勘探对象,整体上,浙东中央背斜带具良好的含油气系统形成的地质要素和较为复杂的成藏作用过程,具有备形成大、中型气田的基本油气地质条件,具有广阔的天然气勘探前景。

Petroleum System in Zhedong Central Anticlinal Zone of Xihu Depression

In order to cognize oil and gas distribution law systematically,to optimize the choice of exploration targets and to carry forward the course of petroleum exploration and development,the basic geologic factors of forming petroleum system in Zhedong Central Anticlinal Zone and its reservoir formation process are comprehensively analyzed by use of the petroleum system theory and quantitative simulation technique.Through researching it is indicated that the mudstones and coal beds in Pinghu Formation of Eocene are the major source rocks,being of higher organic matter abundance and hydrocarbon generating and espelling intensity;the arenaceous rocks in Huagang Formation of Oligocene are the most important reservoir rocks;the mudstones in the upper part of Huagang Formation are the regional caprocks;the matching relation between the trap growth and the generation,expulsion,migration and accumulation of oil and gas is good,showing an ideal place for hydrocarbon accumulation;In the region there are 4 petroleum systems,being mainly the gas systems,in which the Pinghu Formation Huagang Formation system is the most important petroleum formation system with a high hydrocarbon generation and accumulation efficiency,being the principal petroleum exploration target at present in the region;and,as a whole,the Zhedong Central Anticlinal Zone is of fine geological factors of forming petroleum system and relatively complex reservoir formation process,having the basic geologic conditions of forming large and medium sized field and the wide gas exploration prospects.