非线性渗流条件的低渗油藏产能计算方法

为了准确评价低渗透油藏的产能动态规律,针对低渗透油藏的渗流特点,建立了考虑非线性渗流特征的产能计算模型,并用Newton-Raphson方法对模型进行求解.结果表明:用启动压力梯度方法计算的产量将比用非线性渗流方法计算的产量低,特别是在井底流压较大时;而用达西方法计算的产量比用非线性渗流方法计算的产量高,特别是在井底流压较小时.非线性渗流方法比传统的启动压力梯度方法更能够反映低渗透油藏的渗流规律.

A new method for productivity evaluation of low permeability reservoirs with nonlinear seepage characteristics

In order to accurately evaluate the dynamic productivity of low permeability reservoirs,a productivity evaluation model considering nonlinear seepage characteristics is established,and it is solved by means of Newton-Raphson method.The predicted productivity using this method is compared with those predicted using Darcy method and threshold pressure gradient method.The results show that,the productivity predicted using threshold pressure gradient method is lower than that predicted using this nonlinear seepage method,especially when bottom hole flowing pressure is higher,and that the productivity predicted using Darcy method is higher than that predicted using this nonlinear seepage method,especially when bottom hole flowing pressure is lower.As the nonlinear seepage method can better characterize the seepage law in low permeability reservoirs than threshold pressure gradient method,it is proposed to use the nonlinear seepage method for evaluating the productivity of low permeability reservoirs.