新型水驱特征曲线研究与应用

Study and application of new water drive characteristic curve

水驱特征曲线法是注水开发油田指标预测的重要方法之一。针对目前国内常用的水驱特征曲线对油田实际生产指标预测时产生较大偏差的问题,为了准确表征注水开发过程中的采出程度与含水率变化规律,运用油水两相渗流理论推导了一种新型水驱特征公式,建立了适用于不同渗透类型油藏的水驱特征曲线;在此基础上,根据延长油田22个注水开发单元的实际生产数据,拟合出了地质储量与直线段斜率的关系图版,使其更符合实际油田的含水率与采出程度变化规律。研究结果表明1)新型水驱特征曲线公式将标准童氏图版公式中的固定系数7.5修正为由相渗曲线和含油饱和度决定,可以预测不同渗透率油藏的采出程度和含水率变化规律;2)新型水驱特征曲线出现直线段后,含水率从50%上升到98%,在这个含水阶段里,采出程度差值不是一固定常数。应用新型水驱特征曲线对延长油田W区块地质储量和含水率预测的平均相对误差仅为5.2%和2.1%,预测精度大幅度提高。该研究成果对同类油藏注水开发效果评价和注采参数优化具有一定的指导意义和参考价值。

The water drive characteristic curve method is one of the important methods for the prediction of water injection development oilfield indexes.In view of the problem that the commonly used water drive characteristic curve in China has a large deviation in the prediction of actual oilfield production indexes,in order to accurately characterize the recovery degree and water cut change rule in the process of water injection development,a new type of water drive characteristic formula is deduced by using the oil-water two-phase flow theory,and the water drive characteristic curve suitable for different permeability reservoirs is established.On this basis,based on the actual production data of 22 water injection development units in Yanchang Oilfield,the relationship chart between geological reserves and the slope of the straight line is fitted.So that it is more in line with the actual oilfield water content and recovery degree change rule.The result of research shows that:1)The new water flooding characteristic curve formula modifies the fixed coefficient 7.5 in the standard Tong’s chart formula to be determined by the relative permeability curve and oil saturation,which can predict the variation of recovery degree and water cut in different permeability reservoirs;2)After the new water flooding characteristic curve has a straight line,the water content increases from 50%to 98%.In this water-bearing stage,the difference of recovery degree is not a fixed.The average relative errors of the prediction of geological reserves and water cut in Block W of Yanchang Oilfield by using the new water flooding characteristic curve are only 5.2%and 2.1%,and the prediction accuracy is greatly improved.The research results have certain guiding significance and reference value for the evaluation of water injection development effect and the optimization of injection-production parameters in similar reservoirs.