天然水驱油(气)藏压力系数的推导及应用

APPLICATION AND DERIVATION OF THE PRESSURE FACTOR IN NATURAL WATER DRIVE RESERVOIRS

压力系数定义为原始地层压力与静水压之比值。对于分析油藏类型和油藏大小,它是一个重要的参数。压力系数对于任何具体的天然水驱油(气)藏不是一个常数。它的数值主要取决于油(气)井的位置和地层流体的密度差。本文作了压力系数的数学推导,并提供了确定原始油水界面和原始气水界面位置的方法。四个实例的应用结果,表明了本文方法的有效性。

Pressure factor is defined as the ratio of initial reservoir pressure and the corresponding hydrostatic pressure.It is an imporpant parameter for analyzing type of the reservoir and its size. The pressure factor is not a constant for given natural water drive rese- rvoir.Its value depends mainly on the position of the well in which the rese- rvoir pressure is measured and the difference in the densities of the reservoir fluids.A mathematical derivation of the pressure factor is made in this paper, and the method of determining the initial oil-water centact and initial gas- water centact is presented also.The results of four field case examples give the effectiveness of this method.