油水相对渗透率曲线与水驱油藏含水率随采出程度变化的两种类型

目前在油藏动态预测中广泛使用的水驱驱替特征曲线公式,在采出程度E_R与水油比的对数lgF座标上是一条直线.本文改进了上述的预测公式,并且证明了,水驱油藏含水率随采出程度的变化及相应的油水相对渗透率曲线实际上有两种类型.第一种类型是埃尔夏基和小笹提出的公式,在E_R与lgF座标上,公式计算的曲线向E_R轴偏转.第二种类型是本文提出的公式,在E_R与lgF座标上,公式计算的曲线向lgF轴偏转.应用这两个公式,可以准确地预测油藏含水率随采出程度的变化和最终采收率,并计算矿场数据的油水相对渗透率曲线.

TWO TYPES OF CHANGES OF THE RATE OF WATER CUT WITH RECOVERY FACTOR AND THE CORRESPONDING RELATIVE OIL-WATER PERMEABILITY CURVES FOR WATER-DRIVE RESERVOIRS

The characteristic curves for oil displacement by water currently used in prediction of reservoir performance is a straight line on the lg F paper for recovery factor vs water-oil ratio. An improved equation for prediction is proposed, showing at the same time that ahere are practically two types of changes of the rate of recovery with recovery factor and the corresponding relative oil-water permeability curves. The first one derived from the equation proposed by Iraj Ershaghi and Osazuwa Omoregie is expressed on E_R-lgF chart by curves deviating toward the E_R axis, and the other one from the equation proposed by the author by curves deviating toward the lgF axis. Application of both equations may give accurate predictions of changes of rate of water cut with recovery factor as well as the ultimate recovery, and produce relative oil-water permeability curves from available data. In the last part of the paper, calculations are made of data from two dilfferent oil fields in proof of the fact that the theoretical curves agree well with the field data.