汤原断陷新生代构造演化与油气分布

CENOZOIC STRUCTURAL EVOLUTIONS AND HYDROCARBON DISTRIBUTIONS FOR TANGYUAN FAULT DEPRESSION

针对汤原断陷生烃中心认识不清的问题,通过剥蚀量恢复、构造演化及沉积相分析等技术,开展了新生代沉积中心再认识工作。研究认为:汤原断陷新生代构造演化经历了两期伸展,两期挤压;断陷整体构造形态受控于东边界断层,为东断西超的箕状断陷特征;断陷中部沉积中心与沉降中心不一致,中央凸起带在新安村+乌云组—达连河组沉积时期为沉积中心,在宝泉岭组沉积末期隆升为凸起带;盆地原型控制着储层和烃源岩的分布,在中央凸起带上,达一段泥岩未进入生烃门限,生成大量生物气;新安村+乌云组深湖相泥岩分布局限,处于未熟—低熟阶段,导致生油量不足,未形成有效油藏。

In the light of the problem of understanding unclear to the hydrocarbon generating center in Tangyuan Fault Depression,with the help of the following techniques: denudation recovery,tectonic evolution,sedimentary facies analysis and so on,the re-recognition of Cenozoic sedimentary center was caught out. The study achievements show that Cenozoic tectonic evolution has experienced two stages of extension and two stages of extrusion; the overall structural attitude of the fault depression is an half-graben rift controlled by the eastern margin faults and faults in the east and overlies in the west; the sedimentary center was not consistent with that of the settlement in the middle of the fault depression and moreover located in the central uplift belt when deposited at the stage of Xin'ancun + Wuyun and Dalianhe Formations and uplifted at the end of Baoquanling Formation; the distributions of the source rocks and reservoirs were controlled by the prototype basin,in the central uplift belt,the mudstone in the first member of Dalianhe Formation generated a large amount of biogenic gas,which was not in the hydrocarbon generating threshold; the lacustrine mudstones in Xin'ancun + Wuyun Formation distributed limitedly and in the stage of immaturity-low maturity,thus resulted in insufficient amount of oil generated and in the end the effective reservoirs were not accumulated.