鄂尔多斯盆地奥陶系顶面演化与岩溶储层

The structural-interface evolution in Ordovician and karst reservoir in Ordos basin.

1. 西安石油大学石油工程系, 陕西西安710056;2. 东方地球物理公司长庆分院, 陕西西安710021;3. 长庆油田公司勘探开发研究院, 陕西西安710021

Xi'an ShiYou University,Xi'an 710065,China

鄂尔多斯盆地奥陶系碳酸盐岩的风化淋滤带与油气运聚关系密切,古岩溶孔洞是其主要储层。为此,通过恢复鄂尔多斯盆地奥陶纪古构造、风化裸露期古地貌及奥陶系顶面在二叠纪本溪期、太原期、山西期、石盒子期、石千峰期的起伏形态,分析了奥陶系岩溶储层的演化过程。奥陶纪“三隆两鞍一坳陷”的古构造格局控制了沉积相带的展布,是岩溶储层发育的基础;风化裸露期岩溶古地貌格局有利于岩溶储层的进一步发育;奥陶系顶面在本溪期一早中三叠世的起伏形态决定了岩溶储层的后期改造,其在沉积演化过程中,始终处于中部高、东西低的构造格局。分析认为:东部坳陷与中部隆起之间的斜坡带为岩溶储层展布的有利区域,是下古生界油气勘探的重点;东部坳陷中的岩溶残丘为岩溶储层发育的次级有利区,存在较大的勘探潜力。

The formation of Ordovician karst reservoir experienced several tectonic activities.With seismic and drilling data, we restored the Ordovician weathering geomorphy and fluctuant form of top Ordovician in Benxi, Taiyuan, Shanxi, Shihezi, Shiqianfeng of Permian, etc.This paper analyzed the evolution processing of Ordovician karst reservoir.Being the foundation of karst reservoir development, The ancient structure of three uplifts, two saddles and one depression determined the distribution of sedimentary fades.Weathering karst geomorphymade it possible to develop reservoir ulteriorly.The fluctuant form of top Ordovician in Benxi, early andmiddle Triassic determined the later reformation of reservoir.Its structure presented a pattern of "high in themiddle, low in east-west".The slope between eastern depression andmiddle uplift was regarded as a favorable area for reservoir distribution, so it was themain target of petroleum exploration in lower Palaeozoic.Themonadnock of eastern depression was the second favorable area and bearsmuch exploration potentials.