辽河东部凹陷红星地区古近系构造-岩性油气藏成藏控制因素

摘要

红星地区古近系沙河街组和东营组三角洲沉积中发育多套构造和构造-岩性油气藏,由于驾掌寺断裂的长期活动,区内构造和构造-岩性油气藏的形成明显受驾掌寺及其伴生断裂的控制.研究表明,驾掌寺洼陷沙三段烃源岩广泛发育,沙一段和东三段三级层序内的体系域或四级层序中发育的水下分流河道砂体、河口坝及前缘席状砂体和湖进泥岩层形成了7～8套圈闭规模的储盖组合,良好的生、储、盖空间配置构成了成藏的基本条件.同沉积断裂的活动控制着砂体的分布,驾掌寺断裂的西侧下降盘和北东东向的伴生同沉积断裂制约着不同期的砂体发育部位.驾掌寺断裂长期活动,与储层砂体相连构成了区内的主要输导体系,沿断裂带是油气藏形成(特别是构造或构造-岩性油气藏形成)的有利地带.区内早期发育的、位于深部的次级断裂对油气的分布或油气藏的发育具有特别的控制作用,这些断裂一般终止于沙一段上部,沿这些断裂向上运移的油气则趋向于在沙一段中部富集；而沙一中段具有良好的储层和盖层,因此,形成了沿沙一中段砂体广泛成藏的油气分布规律.%There developed several structure oil/gas traps or structure-lithology oil/gas traps in delta deposit of Eogene Shahejie Formation and Dongying Formation, Hongxing area. Because of the long-alive activity of Jiazhangsi fault, structure or structure-lithology oil/gas traps were obviously controlled by Jiazhangsi fault and its associated faults. The study shows that the source rock of Sha 3 Member of Shahejie Formation developed extensively in Jiazhangsi sag, and the system tract of 3rd order sequence or sub-distibutry, mouth bar, delta front sheet sandy and transgrasive lacustrine mudstone of 4th order sequence formed 7-8 trap-scale reservoir and seal combinations in Sha 1 Member of shahejie Formation and Dong 3 Member of Dongjing Formation, which constitute the basic condition to oil/gas trap. Syn-sedimentary fault controlled the development and distribution of sandbody. The western fall part of Jiazhangsi fault and NEE direction extended associated faults controlled the sandy distribution developed in different periods. Long-alive activity of Jiazhangsi fault connecting to reservoir sand formed the major oil/gas transfer system, along which there formed favorable structure or structure-lithology oil/gas traps. Especially, the earlier developed deep senior associated faults make great significance to oil/gas distribution and oil/gas trap development. Most of these senior faults didn't develop in the upper of Sha 1 depo-sitional period, so that oil/gas transferring along these faults tended to assemble at the middle of Sha 1 Member of Shahejie Formation. There was a good combination of reservoir and sealing, and that is why there extensively developed oil/gas trap in middle of Sha 1 Member.