塔中Ⅰ号断裂坡折带构造特征及勘探领域

Structural characteristics and exploration fields of No.1 Faulted Slope Break in Tazhong area

利用新的三维地震资料,综合运用等时地层格架及构造解析方法,分析了塔中Ⅰ号构造带复杂的构造特征及油气富集的差异性。研究结果表明:塔中Ⅰ号构造带是早奥陶世末至晚奥陶世早期形成的大型逆冲断裂带,在上奥陶统沉积前遭受长期侵蚀而形成复杂的断裂坡折带。在上奥陶统良里塔格组沉积时,沿高陡断裂坡折带发育台地边缘礁滩复合体,形成碳酸盐岩沉积坡折带。塔中Ⅰ号断裂坡折带在横向上具有分段性,其间通过构造变换带的调节作用分为结构与形成演化各具特征的5 段,各段油气富集具有明显的差异性。塔中44井区礁滩复合体发育,是实现碳酸盐岩高产、稳产勘探的首选领域;塔中45 井区构造作用与岩溶作用强烈,是寻找大规模缝洞系统的有利领域。这2个区带是在塔中Ⅰ号断裂坡折带寻找大油气田的主攻目标。

Based on the new 3D seismic data, the complex structural characteristics and the difference of oil and gas accumulation in Tazhong No.1 Structural Zone were studied with the isochronous sequence framework and structure analysis. It is indicated that Tazhong No.1 Structural Zone is a complicated faulted slope break resulted from a large thrust belt eroded for a long time from the end of the early Ordovician to the early of the late Ordovician. A composite of carbonate reefs and banks of platform margin in Lian-glitage Formation of the Upper Ordovician was developed along the carbonate slope break. Tazhong No.1 Faulted Slope Break can be divided into five parts with different geometry and development characteristics by the accommodation of transfer zones, which caused the difference of oil and gas accumulation. The thick composite of carbonate reefs and banks in rimed shelf is located in the Tazhong-44 Block. This area is the favorable exploration district and has high and stable production of carbonate along the slope break. There are intensive structural effect and Karst process in Tazhong-45 Block. This area has an advantageous prospect for a large scale fracture-hole reservoir. The two zones are main exploration targets for large oil and gas fields.