广西宁明下二叠统礁古油藏储层及成藏机理

A REMNANT PERMIAN REEF OIL POOL IN NINGMING,GUANGXI AND THE POOLFORMING MECHANISM

广西宁明亭亮下二叠统茅口期生物礁为一已破坏的大型古礁油藏之一。论文对礁储层成因、三史关系（包括埋藏－构造史、有机质演化史和孔隙演化史）及成藏机理进行了深入的探讨。研究表明，礁原生孔隙普遍发育，但由于成岩期多世代方解石的胶结、充填和埋藏压实作用而破坏殆尽，其最终礁储层和有效孔隙的形成主要受控于深埋有机溶蚀作用及礁顶部存在的不整合面和古风化壳岩溶带。同时，紧邻生物礁南部的生油坳陷提供的丰富油源和地下有机酸性流体多期次地运移至礁储集体并在礁古岩溶带的基础上再次进行深埋有机溶蚀作用，为油气储集有效孔隙带的形成和油气运聚提供了最适时、最有效的条件和场所。结合礁顶部覆盖有连片分布的巨厚的三叠系泥质岩作区域盖层、礁油气藏即可形成。

The reef of Maokou Age,Lower Permian in Tingliang and Ningming,Guangxi Autonomous region is one of the largest remnant reef oil pools.The paper provides a great deal of data to describe the reef reservoir origin;histories of burial structure,organic evolution, porosity evolution and poolforming mechanism.It is indicated that at the beginning the primary porosity in the reef was widely developed.However it was completely destroyed due to calcite multi cementation,filling in and burial compaction in the diagenesis.The finally formed reef reservoir and its effective porosity were dominantly controlled by deep burial organic dissolution,unconformity surface at reef top and paleo weathering crust karst.Meanwhile the oil generating depression close to the south of the reef provided a plenty of oil source which together with subsurface organic acidic fluids may have multi migrated to the reef reservoir and further carried out deep buried organic dissolution to the paleokarst on the reef,which offered the most effective conditions and space at the right moment for the forming of effective porosity zone and oil gas migration and accumulation.The thick Triassic shale steadily overlying the top of reef reservoir provided a good regional cap rock.