江汉盆地谢凤桥油田地球化学特征及其勘探意义

谢凤桥油田位于江汉盆地江陵凹陷万城断裂带的南部,油藏圈闭被万城断层分割为复Ⅰ断块和谢凤桥断鼻2个不同类型的构造圈闭,早期认为该油田由谢凤桥断鼻油藏和复Ⅰ断块油藏2个不同类型的独立油气藏组成。根据最新的开发信息和对油藏地球化学特征的研究,认为两者具有统一油气藏的特征。谢凤桥油田膏盐岩层发育,具良好塑性特征的膏盐岩在万城断层两侧对接,形成统一的盖层,在垂向上对油藏进行了封堵。同时,对谢凤桥断鼻古近系新沟嘴组油藏和复Ⅰ断块白垩系渔洋组油藏的原油气相色谱分析以及试油、试采数据表明,复Ⅰ断块渔洋组油藏和谢凤桥断鼻新沟嘴组油藏在横向上是连通的,其具有统一的油水界面,属于同一个压力系统的油气藏。

GEOCHEMICAL CHARACTERISTICS AND ITS EXPLORATION SIGNIFICANCE IN XIEFENGQIAO OILFIELD OF THE JIANGHAN BASIN

Xiefengqiao Oilfield is located in the south of Wancheng fault zone in the Jiangling Sag,the Jianghan Basin.The traps were divided into two different types,i.e.Fu Ⅰ fault block and Xiefengqiao fault nose by Wancheng fault.In the early time,it was considered that Xiefengqiao reservoirs were consisted of Xiefengqiao fault nose reservoir and Fu Ⅰfault block reservoir,which were of different types and independent reservoirs.However,according to the latest production information and geochemical characteristics of the reservoirs,they were a unified reservoir.The gypsum mudstones were well developed in Xiefengqiao Oilfield.These gypsum mudstones with good plasticity were jointed with each other on both sides of Wancheng fault,so an unified seal was formed.Meanwhile,according to gas chromatography analysis of crude oils from the Neogene Xingouzui Formation of Xiefengqiao fault nose and the Cretaceous Yuyang Formation of FuⅠfault block,it can be concluded that reservoirs in Yuyang Formation in FuⅠfault block and Xingouzui Formaion in Xiefengqiao fault nose were laterally connected.They showed the same oil/water interface and the same pressure system.