压实流盆地油气运移动力学模型与数值模拟——以东营凹陷为例

The Dynamic Models and Numerical Simulation of Secondary Petroleum Migration in Compactional Flow Basins —An Example From the Dong Ying Depression

针对压实流盆地“离心”式流体势场性质和泥质岩排流模式，建立了东营凹陷沙三段古水动力学概念模型和“准三维非稳定流”数学模型。将古水动力场均衡网格与压实－排流结点网格系统迭加，由达西定律和水均衡原理建立了水均衡差分方程，从而为古水动力学、古流体势场和石油二次运移数值模拟提供了数值方法。模拟结果表明，在东营期末（２５Ｍａ），高势区位于利津和牛庄洼陷中心，最大可达５９０００ｍ２／ｓ２，并向盆地边缘逐渐降低。油气由高势区向低势区呈“离心”式运移，这正是控制油气呈环、带状聚集与分布的区域动力学条件。模拟结果还显示，沙三段在明化镇期（５Ｍａ）、东营期（２５Ｍａ）和现今，其石油的运移速度分别为３０～４０ｋｍ／Ｍａ、５～２５ｋｍ／Ｍａ和５～１０ｋｍ／Ｍａ。

The conceptual model of paleohydrodynamics and mathematical model of pseudo3D nonstationary flow for the Es3 member were built according to 'centrifugal flow' characteristics of the fluid potential field of compactional flow basin as well as to expelling style of fluids from mudstones. Isostatic nets of paleohydrodynamical field were superimposed on nodal nets of compactiondisplacement fluids ,and the diffential equations of hydrodynamics were writen by means of Darcy′s law and hydraulic isostation,which provides a numerical method for simulating paleohydrodynamics,paleofluid potential field and secondary hydrocarbon migration . The results of numerical simulation showed that the high potential values(Max.59000m2/s2)were located in the centre of the Lijing and Niuzhang areas and descended towards edges of the depression at 25Ma(late Dongying) .Oil migrated from higher potential belts to lower ones in 'centrifugal flow' ,which was the regional dynamic condition of controlling petroleum accumulation and distribution. The simulations also revealed that migrating velocities are 30￣40km/Ma at 5Ma,5￣10km/Ma at 25Ma and 5￣10km/Ma at present in the Es3member,respectively. The main driving forces of secondary migration were different in geologic times and spaces.