塔里木盆地塔北地区中-下奥陶统顶面多期剥蚀过程与油气关系

剥蚀量恢复是古构造演化恢复的基础，对于恢复盆地沉积地层格架，研究盆地隆坳格局迁移、油气分布聚集关系等具有重要意义。我国最大沉积盆地塔里木盆地的塔北地区中-下奥陶统地层油气资源丰富，在经历多次构造运动后，抬升剥蚀严重。本文按照“同层多期”的思想识别了对塔北地区油气勘探举足轻重的中-下奥陶统顶面经历剥蚀的5个主要构造期，采用“地震地层综合法”，在精细地震资料解释的基础上计算了其在5个主要构造期的剥蚀量。通过分析剥蚀过程，认为中-下奥陶统顶面从加里东中期到喜山期剥蚀范围依次减小，剥蚀厚度在加里东中期最大剥蚀可达915 m，位于现在的英买1井附近。海西早期剥蚀最大厚度达892 m，位于现今两北地区北部一带；海西晚期最大剥蚀厚度位于现今的齐古1井附近，剥蚀量可达690 m；印支—燕山期最大剥蚀厚度可达546 m，位于现今阿北1井附近；喜山期对中-下奥陶统顶面的影响已经不如前几期，最大剥蚀厚度仅338 m，位于现今的沙雅6井附近。就5期总剥蚀厚度而言，最大可达936 m，位于顺13井附近。油气运聚的总体趋势是在塔北地区北部不断抬升遭受广泛剥蚀的前提下，油气沿着以中-下奥陶统顶面为核心辐射出的立体复杂疏导体系向高部位的塔北隆起运移成藏。油气有利勘探区应在阿克库勒凸起和“两北”地区的古斜坡位置，正如塔北地区满深1井（沙雅县境内）获得高产油气流的勘探实践所印证。

Ordovician top surface and its relationship with oil and gas in the Tabei area,Tarim Basin

The restoration of denudation is the basis of the restoration of paleostructure. It is of great significance for restoring the sedimentary stratigraphic framework of the basin, studying the migration of the basin uplift pattern, and the relationship of oil and gas distribution and accumulation. In the Tarim Basin, the largest sedimentary basin in China, the Middle-Lower Ordovician strata are rich in oil and gas resources. After some tectonic movements, they have severe uplift and erosion. This study identifies the five major tectonic movements of the Middle-Lower Ordovician top surface experiencing denudation in the Tabei area according to the idea of --“same layers and multiple periods”, and uses the “seismic stratigraphic synthesis method” to calculate its various amount of erosion during the main tectonic movements. By analyzing the erosion thickness map, it is considered that the erosion range of the Middle-Lower Ordovician top surface decreases from the Middle Caledonian to the Himalayan Period, and the maximum erosion thickness in the Middle Caledonian can reach 915 m, which is located near the current Yingmai 1 well. The maximum thickness of denudation in early hercynian reaches 892 m, which is located in the northern part of the present northern and northern regions. The maximum thickness of denudation in Late Hercynian is near the current Qigu-1 well, which can reach 690 m. The thickest point is located near Abei 1 well at present; the influence of the Himalayan Period on the unconformity is not as good as in previous periods, and the maximum erosion thickness is only 338 m, which is located near Shaya 6 well today. In terms of total erosion thickness, it can reach a maximum of 936 m and is located near Shun 13 well. The general trend of oil and gas migration is that under the condition of the continuous uplift of the northern part of the Tabei area, the oil and gas migrated along the three-dimensional drainage system centered on the Middle-Lower Ordovician top surface to the higher part of the northern part of the Tabei uplift. The favorable exploration area should be located in the ancient slopes of the Tabei uplift and the “liangbei” regions, just as the high-production oil gas flow was obtained in Manshen 1 well （in Shaya County） in the Tabei area.