查干凹陷下白垩统含油气系统特征及勘探方向

查干凹陷下白垩统含油气系统以巴音戈壁组二段为主力烃源岩、巴音戈壁组二段和苏红图组一段为主要储集层,构成自生自储和下生上储两套成藏组合。盆地热模拟结果表明,白垩纪末期烃源岩达到成熟阶段,为生、排烃高峰期,白垩纪末的燕山运动(65 Ma)为系统的关键时刻。根据油气系统的平面、剖面分布,结合油气运移方向和圈闭条件分析,认为毛敦侵入带和巴润断鼻带为下步勘探的有利部位。

Characteristics of Lower Cretaceous petroleum system in Chagan sag and exploration direction

There are two petroleum systems in Chagan sag with the 2~(nd) member of Bayingebi Formation of the Lower Cretaceous as the major source rocks and the 1~(st) member of Suhongtu Formation as the major reservoir rocks.In one petroleum system,the source rocks and reservoir rocks are in the same horizon,while in another one,the source rocks are located below the reservoir rocks.Thermal modeling in the basin shows that the source rocks would have be- come mature by the end of Cretaceous,and hydrocarbon generation and expulsion would have been peaked.Yanshan movement (65 Ma) at the end of Cretaceous has been the crucial period for the petroleum systems.Based on compre- hensive analysis of the charging degree of hydrocarbon,migration direction and trapping conditions,it is believed that Maodun intrusion zone and Barun fauh-nose zone are favorable for exploration.