七泉湖断裂的分期分段性封闭与油气充注关系

吐哈盆地七泉湖断裂位于七泉湖构造带南部,断层的封闭与开启对七泉湖和玉果2个油田的形成起关键作用。通过断裂封闭性的研究和原油地球化学参数的分析,证实七泉湖断裂具有分期、分段性封堵的特点,白垩纪末—古近纪断层封闭性较差的部位即为下盘油气向上盘运移的充注点,由于下盘烃源岩成熟并大量排烃主要发生在喜马拉雅运动期,喜马拉雅运动晚期断层封堵性的逐渐增强导致油气充注作用减弱,而断裂开启和油气充注主要发生在古近纪。七泉湖断裂的分段性封堵以及充注时间较短,是导致该地区侏罗系油气供给不足的主要原因。

Relationship Between the Sealings by Stages and Sections of Qiquanhu Fault and the Petroleum Charging in Tuha Basin

Qiquanhe fault in Tuha basin is located in southern Qiquanhu structural belt.The sealing and open of the fault determine the oil-gas charging point and migration direction.Therefore,this fault plays a key role in formation of Qiquanhu and Yuguo oilfields.The study of the fault sealing and analysis of the crude oil geochemical parameters show that Qiquanhu fault is characterized by differential plugging by stages and sections.At the end of Cretaceous to Paleogene,the place of poor sealing could be the charging point of oil and gas migrated from the lower wall toward the upper wall.Because the source rocks of the lower wall are relatively late,in mature time,mass hydrocarbon expulsion and migration.The gradually increasing of the fault sealing in late Himalayan movement leads to the decreasing of oil-gas charging effect,so the fault open and oil-gas charging mainly happen in Paleogene.The sealing time by stages and sections of this fault determines that the oil-gas charging in Qiquanhu structural belt is local and short in time.This may be the key reason for insufficient supply of oil and gas of Jurassic from the source rocks in this area.