特高含水期甲型水驱特征曲线的改进

Improvement of water displacement curve for water flooded oil reservoirs at ultra-high water cut stage

室内试验和矿场实践表明,现有水驱特征曲线在特高含水期适用性差,出现偏离直线段上翘的现象,影响水驱开发动态的准确预测。为此,提出适用于特高含水期的新型水驱特征曲线。首先提出适用性较强的油水相对渗透率比值与含水饱和度关系表征方程,得到可以充分考虑开发后期上翘现象的新型水驱特征曲线,指出原有水驱特征曲线是新型水驱特征曲线在含水率较低时的一个特例,并提出通过公式转化和线性试差的方法求解新型水驱特征曲线方程中的参数。计算结果表明,新型水驱特征曲线在特高含水期预测开发动态比传统的水驱特征曲线更为准确。

A lot of experimental results and field practices show that the water displacement curve may deviate out from a straight line and unwrap at an ultra-high water cut stage,thus the adaptability of the conventional water displacement curve is poor for water flooded reservoirs at the ultra-high water cut stage.An improved water displacement curve suitable for ultrahigh water cut stage was proposed.Firstly,a new characterization equation for the relationship between water-oil relative permeability ratio and water saturation suitable for high water cut was proposed,and then a new water-flooding characteristic curve was derived accordingly.It is found that the conventional water displacement curve can be as a special case of the improved model at low water cut conditions.A method based on equation transformation and linear trial and error method was proposed to determine the parameters in the new water displacement curve equation.A case study was conducted,and the result shows that the new water displacement curve is more accurate than the conventional model in predicting the production performance for reservoirs at ultra-high water cut stage.