油藏“水动力”压力特征成因——以伊拉克鲁迈拉油田祖拜尔组第四油藏为例

Causes of hydrodynamic pressure distribution: A case of the 4^(th) Pay in Zubair Formation, Rumaila Oilfield, Iraq

基于理论分析与油藏实例调研,系统总结油藏"水动力"压力特征的成因类型,应用排除法和数值模拟法确定伊拉克鲁迈拉油田祖拜尔组第四油藏(4th Pay)"水动力"压力特征成因。"水动力"压力分布特征成因类型可分为动态水体类、油藏分区类和流体变密度类,其中动态水体类可由水动力油藏或周边油田衰竭开采导致。4th Pay油藏水层压力由北向南逐渐降低而无倾斜油水界面,结合4th Pay油藏地质特征,应用排除法确定4th Pay油藏压力的"水动力"特征属动态水体类。数值模拟进一步表明,4th Pay油藏油水界面调整时间尺度远大于油藏开发时间尺度而远小于成藏时间尺度,"水动力"压力特征为周边油田衰竭开采所致。结合区域地质研究和周边油田开发历史调研,推测其为受南部劳扎塔因油田衰竭开发影响。

This paper summarizes the genetic causes of hydrodynamic pressure distribution based on study of theoretical mechanisms and reservoir cases and determines the causes of the 4th Pay in the Zubair Formation of the Rumaila Oilfield using exclusive method and numerical simulation. These causes can be classified into three types as the hydrodynamic aquifer type, the reservoir compartmentalization type and the changing fluid density type. Among them, the hydrodynamic aquifer type may result from depletion of hydrodynamic pools or adjacent oilfields. The aquifer pressure in the 4th Pay reservoir decreases from north to south, without tilted oil-water contact. Considering the geological settings of the 4th Pay reservoir, its hydrodynamic pressure distribution is hydrodynamic aquifer. By numerical simulation of the pressure distribution, fluids contacts geometry and adjusting time, the hydrodynamic aquifer in the 4th Pay is due to the depletion of adjacent oilfields. Combining regional geological setting and investigation of production history of adjacent oilfields, the hydrodynamic pressure distribution phenomenon in the 4th Pay reservoir is affected by the depletion of the Raudhatain oilfield in the south,