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以含油气系统理论为指导，论述了组成西湖凹陷含油气系统的基本特征，分析了控制油气系统发育的主要因素，并探讨了该凹陷的油气勘探远景与方向。研究表明，西湖凹陷发育4个含油气系统，多属凝析油与天然气系统，其中平湖组—花港组系统为最主要的含油气系统，是本区油气勘探的主要对象。含油气系统发育受源岩、储层、盖层、构造演化、输导网络及保存条件等多种因素的联合控制；凹陷具备形成大、中型气田的基本油气地质条件，具广阔的油气勘探前景；应在寻找平湖组含油气系统和构造型油气藏的同时，加强对深部层系与非构造油气藏的油气勘探工作。

CHARACTERISTICS AND EXPLORATION EVALUATION OF THE PETROLEUM SYSTEMS IN XIHU DEPRESSION OF EAST CHINA SEA

By applying the petroleum system theory,the basic characteristics of the petroleum systems in Xihu Depression are expounded,the principal factors controlling the development of petroleum systems are analyzed,and the prospects and trends of exploring for oil and gas in the depression are discussed in the paper.Through research,it was shown that in Xihu Depression,there are four petroleum systems of which most belong in the condensate and natural gas systems,in which the Pinghu Formation—Huagang Formation system is the most important petroleum system and the marjor target of exploring for oil and gas in the depression.The development of petroleum system is controlled by many factors,such as cource rock,reservoir,caprock,tectonic evolution,transport network and preservation condition,etc.Xihu Depression is of a vast range of prospects for exploring for oil and gas,because it has the basic geological conditions of forming large and medium sized gas fields.While surveying the Pinghu Formation petroleum system and structural oil and gas reservoirs,the exploration works of deep strata and non structural oil and gas reservoirs must be strengthen ed.