塔里木盆地塔河油田奥陶系大型油气藏形成条件

塔河油田位于塔里木盆地北部沙雅隆起阿克库勒凸起的西南部，它是在长期发育的阿克加勒鼻状古隆起基础上形成的下奥陶统盐碉岩溶－缝洞型大型油气田。受区域构造－沉积背景控制，塔河地区下奥陶统属于碳酸盐岩开阔台地环境，一直处于继续性隆起状况，是油气运聚的长期指向区，并经历了多欠的构造运动。岩溶作用和成岩作用的叠加改造，形成了具强烈非均质性的岩溶－缝洞型储层，油气主要赋存于距风化壳不整合面200m范围内的岩溶缝洞系统中。勘探成果表明，长期发育的继承性古隆、丰富的多油源供给、强烈非均质性的岩溶－缝洞型储层及优良的储盖配置、多层次和多类型圈闭的广泛发育、以及由岩溶缝洞－断裂－不整合面组成的疏导体系，是形成塔河大型油气田的重要条件。

Formation Condition of Large-scale Oil-gas Pool in Ordovician Carbonate Rock in the Tahe Oil Field, Tarim Basin

The Tahe oilfield located in the southwest of the Akkol uplift in the northern Tarim basin is a large-scale oilfield of karst-fractured reservoir in Lower Ordovician carbonate rocks and was formed under the background of a long developed palaeo-uplift. Controlled by regional tectono-sedimentary setting, the Tahe area in the Early Ordovician was in an open carbonate platform environment and in an inherited uplift. For a long time, it was the targeted area of oil/gas migration and accumulation, and underwent multi-episode tectonic movements, karstification and diagenesis. The karst-fractured reservoir presents the characteristics of intense anisotrope and lowest matrix porosity/permeability. Oil and gas are mostly accumulated in the caves and fracture system of the karst-buried hills within the bed of 200 meters below the weathered unconformity. Exploration practices indicate that the formation of the Tahe oil reservoir was controlled by long-term developed, inherited palaeo-uplift, rich-supply sources, intensive anisotropic karst-fractured reservoir and good caprock associations, widely developed traps of different types, and the conduit system consisting of karst palaeo-hill fractures and pore spaces and unconformity surfaces.