伊通盆地莫里青断陷古近纪断裂活动对基岩油气成藏的影响

位于伊通盆地南端的莫里青断陷，目前共有53口探井钻达基岩，多口井见油气显示，有2口井获得工业油流，证明莫里青断陷基岩具有一定的油气勘探潜力，但是，对基岩油藏的形成与分布规律还缺乏相应的认识。文中在对莫里青断陷古近系的断裂发育及演化特征分析的基础上，根据圈闭形成时期及特征，将莫里青基岩潜山划分为古地貌潜山、同生潜山、后生潜山3大类。研究认为，永吉组沉积时期活动的断裂与烃源岩的生排烃期相匹配，是沟通源岩与基岩圈闭的有效运移通道，这些断裂与不整合面、砂体构成良好的阶梯状疏导体系。基岩储层的储集空间主要为次生孔隙和裂缝，断裂活动对于裂缝的形成有着重要的作用，长期继承性活动的断裂影响有利储层的分布。综合分析各项因素认为，同生断阶潜山对基岩油气成藏最为有利。

There are 44 exploratory wells drilled to the basement rocks in Moliqing Depression, which is located in south of Yitong Basin. Oil gas shows are found in a few of wells and commercial oil flows are found in two wells of them, which means that the basement rocks in Moliqing Depression has a certain hydrocarbon exploration potential. However, the understanding on formation and distribution of basement hydrocarbon reservoir is still not constructed. On the basis of the analysis of Paleogene fault evolution in Moliqing Depression and according to the formation period and trap geometry, three categories of basement buried hills are divided in Moliqing Depression, including paleogeomorphic hills, contemporaneous hills and epigenetic hills. Research suggests that fault activities during the deposition of Youngji Formation can match with the hydrocarbon generation and expulsion of main source rocks, which shows that these faults are the effective migration pathway between source rocks and basement traps and they also constitute step migration system with unconformity surface and sandstone body. The reservoir spaces of basement rocks are mainly secondary pores and fractures, and the fault activities play an important role in the formation of fractures. Long?鄄term successive fault activities have an effect on the distribution of favorable reservoir. Considering all factors, it is suggested that contemporaneous fault terrace buried hills are the most favorable traps for the hydrocarbon accumulation of basement rocks.

10.6056/dkyqt201502003