塔里木盆地古城地区奥陶系碳酸盐岩近年来展现出良好的勘探潜力.通过对古城地区钻遇奥陶系10余口探井的岩心、岩石薄片观察和阴极发光、包裹体、沥青反射率分析以及地震资料解释,并结合区域研究成果,系统分析了古城地区奥陶系碳酸盐岩的成储、成藏条件.研究表明:①古构造-流体作用是控制下奥陶统鹰山组下段—蓬莱坝组滩相白云岩储层发育及油气聚集成藏的重要因素;②二叠纪后的构造热事件对油气成藏起到关键的调整改造作用,受岩浆热液活动的影响,加里东期—早海西期原生油藏发生大规模裂解,形成原油裂解气藏及残留古油藏;③奥陶系油气藏的形成与演化经历了3个阶段,包括原生油气藏形成,古油藏破坏裂解生气,以及气藏调整、破坏、再形成阶段,并具有多期演化的油气成藏模式.指出古城低凸起西部、北部的生储盖组合条件良好,断裂和岩浆侵入影响较小,是有利油气勘探区.

The Ordovician in Gucheng area of Tarim Basin has shown good exploration potential in recent years. Based on observation of the core and petrographic thin section, analysis of cathodoluminescence, inclusion and bitumen reflectance of more than 10 Ordovician exploration wells, and interpretation of seismic data in Gucheng area, and combined with regional research results, the reservoir forming and hydrocarbon accumulating conditions of Ordovician carbonate rocks in Gucheng area are systematically analyzed. The results show that: (1) Paleostructure-geofluid processes is an important factor controlling the development of granular dolomite reservoir and hydrocarbon accumulation in the lower member of Yingshan Formation and Penglaiba Formation of Lower Ordovician. (2) Tectonic thermal events after Permian played a key role in adjustment and transformation of oil and gas accumulation. Under the influence of magmatic hydrothermal activity, large-scale oil cracking of primary reservoir occurred in Caledonian-Early Hercynian period, forming crude oil-cracked gas reservoirs and residual paleo reservoirs. (3) The formation and evolution of Ordovician oil and gas reservoirs have experienced three stages, including the formation of primary oil and gas reservoirs, the destruction of ancient reservoirs and the generation of oil-cracked gas, and the adjustment, destruction and reformation of gas reservoirs. It is pointed out that the west and the north of Gucheng low uplift are favorable for oil and gas exploration because of good combination conditions of source, reservoir and caprock, and less influence of faults and magmatic intrusion.