鄂尔多斯盆地东部二叠系流体包裹体与天然气成藏

摘要

The gas accumulation time and process of the Permian（including Taiyuan,Shanxi,Shihezi and Shiqianfeng formations） gas reservoirs in eastern Ordos basin were described by reservoir fluid inclusions.The result shows that the Upper Paleozoic reservoirs are rich in type of fluid inclusions,mainly including saltwater inclusion,hydrocarbon-bearing inclusion and gaseous hydrocarbon inclusion.The distributions of homogenization temperature of the fluid inclusions in different gas strata are of significant differences with single frequency,dual-frequency or multi-frequency.The reservoir fluid was characterized by high salinity.Integrated with the burial history and thermal history analyses,the effective gas accumulation times of Taiyuan,Shanxi,Lower Shihezi and Upper Shihezi-Shiqianfeng gas strata were determined.The gas accumulation process of the Permian gas reservoir groups could be divided into two stages： the early durative stage from Jurassic to Early Cretaceous,in which the primary gas reservoirs of Taiyuan and Shanxi formations were formed with ＂diffused gas pool＂ in Lower Shihezi Formation;the late lifting and adjustment stage of Late Cretaceous,in which natural gas was quickly adjusted by way of bunched flow,with connections among micro-fractures and faults,and Lower Shihezi gas reservoir and Upper Shihezi-Shiqianfeng secondary gas pool were formed.%应用储集层流体包裹体精细描述了鄂尔多斯盆地东部二叠系（太原组、山西组、石盒子组及石千峰组）气藏的成藏时间和成藏过程。研究表明,二叠系储集层流体包裹体类型丰富,主要包括盐水包裹体、含烃包裹体和气态烃包裹体。不同含气层系流体包裹体均一温度分布差异较大,呈单段式、双段式或多段式,成藏期古流体具有高矿化度性质。结合盆地埋藏史和热史分析确定出太原组、山西组、下石盒子组及上石盒子组-石千峰组含气层系的有效成藏时间。研究区二叠系气藏群成藏过程可以分为两个阶段：早期持续埋深阶段（侏罗纪-早白垩世）,太原组和山西组原生气藏形成,下石盒子组＂泛气藏＂形成;晚期抬升调整阶段（晚白垩世）,天然气呈束状流快速调整,微裂缝和断裂起沟通作用,下石盒子组气藏和上石盒子组-石千峰组次生气藏形成。