Abstract:

Thirtyseven crude oil samples and forty rock samples were analyzed by geochemistry analysis methods of GCMS，carbon isotopic and light weight hydrocarbons for the further exploration research of Zhu Ⅲ depression. Based on the results, comprehensive comparison between oil source and hydrocarbon source rocks was done again and new cognition was gained. The results showed that the deep lacustrine facies source rock of Wenchang Formation is the major source rock of Wenchang B sag in Zhu Ⅲ depression, rather than the shoreshallow lacustrine facies source rock; and the swamp facies source rock of Enping Formation is the major source rock of Wenchang A sag in Zhu Ⅲ depression. The main contributions of the crude oil were deep lacustrine facies source rock of Wenchang Formation in Wenchang B sag (Structure WC19-1 and WC19-2), swamp facies source rock of Enping Formation in Wenchang A sag(Structure WC9-1, WC9-2, WC9-3, WC14-3, WC11-2). The crude oil in west Qionghai uplift (Structure WC13-1、WC13-2、QH18-1、QH23-1) primarily came from the deep lacustrine facies rocks of Wenchang Formation in Wenchang B sag, while that in east Qionghai uplift (Structure WC19-6N、WC7-2、WC7-3、WC8-3) mainly came from source rocks of Enping Formation in Wenchang A sag. Two episodes of hydrocarbon filling had taken place in the study area.

Key words: Zhu Ⅲ depression；source rock； feature of crude oil； oil source; , hydrocarbon migration