孤南洼陷水动力场演化与油气运聚

Evolution of Hydrodynamics and Petroleum Migration-Accumulation in Gunan Sub-Sag

根据孤南洼陷的沉积、构造和水化学特征,将其水文地质作用划分为3个水文地质旋回:异常压力的中上始新统-下渐新统旋回、压力过渡状态的中上渐新统旋回和正常压力的中新统-第四系旋回。洼陷的水动力场演化具有明显的阶段性,其中油气生成和聚集的主要层段沙三段和沙二段经历了5个水动力演化阶段,现今主要表现为压实流特征。洼陷的水动力场对油气运聚和成藏具有明显的控制作用,通过对沙河街组主力储集层在油气运移期穴馆陶组沉积末期雪古水动力场的数值模拟,发现该时期压实流促使油气向洼陷边缘的越流泄水区聚集成藏,形成了东部孤东断裂带、西北部孤南断层上升盘及西南斜坡3个油气富集带。

According to the depositional, structural and hydrochemical features in Gunan sub-sag, the hydrogeological process is divided into 3 cycles of hydrogeology of Middle-Upper Eocene to Lower Oligocene in abnormal pressure, Middle-Upper Oligocene in transitional pressure and Miocene to Quaternary. The evolution of hydrodynamic field in this sub-sag underwent 5 stages of Es3-Es2 members which are the major zones of petroleum generation and accumulation. Nowadays, the hydrodynamic field assumes compaction-driven flow, being of significant controls on the petroleum migration and accumulation. It is found from simulation of paleo-hydrodynamic field of petroleum migration stage of major reservoir (Shahejie formation) that it is the compaction-driven flow of this stage that allow the petroleum to accumulate towards the margin of Gunan sub-sag into crossflow discharge areas followed by shaping three accumulations of the Gudong fault zone in eastern the sub-sag, the upthrow side of Gunan fault in northwestern the sub-sag and the slope in southwestern the sub-sag.