Abstract: The whole logic of hydrocarbon system includes identifying,classifying,depicting and evaluation.Its sole purpose is to correlate between(sub-)hydrocarbon systems and then to select the most prospective one to explore and exploit.This paper,based on the latest conclusions resulting from petroleum geology,basin model and geochemistry,splits the Qikou Sag into two hydrocarbon systems,which are named Sha3(!)and Shal(!).The former can be subdivided into Sha3-E(!) sub-system and Sha3-N(!)sub-system.The overall evaluation,including the source appraisal of(sub-) hydrocarbon system,shows that Qikou Sag has very good expectation:Sha3(!)system should be the highlight of late exploration,especially the Sha3-E(!)sub-system whose pre-Teritary and the others should be focused on.Shal(!)system has good expectation as well.

Key words: Qikou Sag, hydrocarbon system, sub-hydrocarbon system, source appraisal

摘要： 含油气系统从识别、划分、描述到评价是一个完整的不可分割的整体,其最终目的是要对各系统进行比较,筛选出最有勘探前景的系统,并指出勘探方向.以歧口凹陷为例,根据石油地质、盆地模拟和地球化学的最新研究成果,揭示出歧口凹陷有两个含油气系统,即沙三含油气系统和沙一含油气系统,前者又可分为沙三-下第三系亚含油气系统和沙三-上第三系亚含油气系统.在此基础上,尝试以含油气系统为基本单元,分三个单元进行资源评价,综合评价表明歧口凹陷具有良好的勘探远景,并指出沙三含油气系统应是今后勘探的重点,其中沙三-下第三系亚含油气系统最具勘探前景,应特别注意加强该亚系统前第三系及其它层位的勘探.沙-含油气系统仍具有较好的勘探前景.

关键词: 歧口凹陷, 含油气系统, 亚含油气系统, 资源评价