塔里木盆地巴楚-麦盖提地区油气勘探领域评价

塔里木盆地巴楚-麦盖提地区寒武纪-中晚奥陶世碳酸盐岩台地经历了加里东期及海西早期的剥蚀,呈向北减薄的楔状体,不同层位的碳酸盐岩发生多期岩溶作用;石炭-二叠纪经历了多次海平面升降旋回,形成碳酸盐岩与碎屑岩间互的岩相序列;中生代持续隆升,广泛剥蚀;喜马拉雅期巴楚地区断裂强烈活动,麦盖提地区调整为南倾的斜坡,古近系-中新统地层超覆于前新生代巴楚古凸起上.针对巴楚-麦盖提地区多期改造、晚期强烈变形定格的构造特征,提出"构造活动的相对稳定区、油气长期运移指向区、有效封闭带"是油气构造带评价的关键因素,划分出3类风险程度不同的勘探构造带.重点分析了石炭-二叠系碳酸盐岩储层、中下奥陶统风化壳岩溶储层、上奥陶统台缘相带及寒武系盐下白云岩储层等4个勘探领域.

Evaluation of oil and gas exploration domains in Bachu-Maigaiti area of Tarim Basin

Due to erosions from Caledonian to early Hercynian,Cambr ian-Middle-Late Ordovician carbonate platform in Bachu-Maigaiti area in the Tarim Basin is thinning northward with the shape of wedge.Different layers of carbonate rock have experienced stages of multi-phase karst effect.From Carboniferous to Permian,a number of sea-level cycles result in alternating layers of carbonate rocks and clastic rocks.Continuing uplifts lead to extensive erosions in Mesozoic.Faults in Bachu region move strongly in Himalayan and Maigaiti region adjust to slope southwards.The strata of Eugene-Pliocene overlap the ancient Bachu uplift of pre-Cenozoic.Taking into consideration of structural characteristics of multi-stage transformation and late-stage strong deformation in Bachu-Maigaiti area,it is pointed out in this paper that,relatively stable region in tectonic movements,long-term targets of hydrocarbon migration and effective sealing belts are the key factors for evaluations of oil and gas tectonic belts.Three tectonic belts with different exploration risks are divided.Four exploration domains are analyzed,including Carboniferous-Permian carbonate reservoir,Middle and Lower Ordovician karst weathering crust reservoir,Upper Ordovician platform edge facies belts and dolomite reservoir under salt in Cambrian.