对特高含水期水驱特征曲线上翘问题的新认识

NEW UNDERSTANDINGS OF THE UPTURNED PROBLEM FOR THE WATER FLOODING CHARACTERISTIC CURVE AT EXTRA-HIGH WATERCUT STAGE

室内实验和矿场实践表明,水驱特征曲线在特高含水期会出现偏离直线段上翘的现象从而会影响其使用范围。首先将渗透率曲线处理成油水两相相对渗透率比值的对数与含水饱和度始终为直线关系之后的形式,再利用正交试验的方法分析不同类型相对渗透率曲线、储层韵律性、油水黏度比以及储层纵向渗透率等因素对于水驱特征曲线上翘时机的影响。通过正交试验分析后发现相对渗透率曲线在高含水饱和度阶段的异常状况对于水驱特征曲线上翘的影响有限,由注入水无效循环形成的生产井的产出结构变化才是水驱特征曲线上翘的重要原因。最后通过物模实验与实际生产资料对所得出结论进行了验证。

Laboratory experiments and field practice show that the water-flooding characteristic curve deviating from the straight line segment and upturning phenomena will affect its scope of using. At first, the permeability curves were changed into the linear relationship between the logarithm the water saturation, and then using the orthogonal testing of the oil-water two-phase relative permeability ratio and method, the effects and influences were analyzed for the opportunity of the upturn of the water-driven characteristic curve caused by different types of the relative permeability curve, reservoir rhythm, oil-water viscosity ratio, reservoir vertical permeability and other factors. The orthogonal ex- periment analysis found that the abnormal condition of the relative permeability curve at the stage of high watercut sat- uration affects little on the upturn of the water driven characteristic curve, the important reason for the upturn is the production structure changes of the producing wells caused by the invalid circulation of the injected water. Finally, the conclusion is verified by the experiments of physical model and the actual production data.