伊通盆地莫里青断陷地层压力演化与油气运聚

Pressure Evolution in the Moliqing Fault-Depression,Yitong Basin

以伊通盆地莫里青断陷现今压力场特征及单井超压演化历史的研究为基础，应用2D盆地模拟方法，对伊通盆地莫里青断陷地层压力演化进行了模拟恢复，并探讨了压力演化与构造运动及油气运聚的关系。研究结果表明：莫里青断陷地层压力演化明显经历了始新世早一中期（57．8-39Ma）、中始新世一晚渐新世（39-23．7Ma）、晚渐新世一现今（23．7-0Ma）3个“增压一泄压”旋回，现今地层压力基本为常压，仅靠山凹陷底部发育弱超压；压力演化的旋回性主要受控于构造运动的旋回性；地层压力演化对油气运聚具有重要的影响作用，超压释放期油气运聚活跃，断裂是超压释放与油气运移的主要通道，与断裂输导体系有关的区带为有利的油气勘探对象。

Based on the study on the present characteristics of pressure field and excess pressure evolution of a single well in the Moliqing fault-depression in the Yitong basin, the formation pressure evolution of the Moliqing fault-depression is restored by using the method of 2D basin modeling, and the relationships between pressure evolution and tectonic movement, and hydrocarbon migration and accumulation are further discussed. The results indicate that the formation pressure evolution in the study area has obviously undergone three cycles of accumulation and expulsion, which occurred during the Early Eocene to Middle Eocene （57.8 - 39 Ma）, the Middle Eocene to Late Oligocene （39 - 23.7 Ma）, and the Late Oligocene to present （23.7 - 0 Ma）. The present formation pressure is mainly normal except for low overpressure at the bottom of the Kaoshan depression. The cycles of pressure are controlled by the cycles of tectonic movements. Pressure evolution has an important influence on hydrocarbon migration and accumulation because hydrocarbon migration and accumulation occurred actively during overpressure expulsion. Fault is the major channel for overpressure expulsion and hydrocarbon migration. Hence the areas that developed fault conduit systems are the favorable targets for hydrocarbon exploration in the Moliqing fault-depression.