聚合物驱试井分析叠加原理适用性的探索

Applicability Exploration of Superposition Principle for Pressure Transient Analysis in Polymer-flooding System

建立考虑聚合物剪切变稀特性的聚驱试井数学模型,基于矩形网格和井筒周围径向加密的复合网格。采用有限体积方法求得数值解,将数值解与叠加原理得到的注聚井停注压降进行对比。结果表明:叠加原理计算得到的注聚井关井井底压力值远低于数值解,说明叠加原理不能用于聚合物驱试井解释。在实测注聚井压降资料解释中,叠加原理得到的渗透率明显偏低,进一步证明了叠加原理不适合非线性聚驱试井模型,数值方法更加适用于聚驱试井解释。研究结论适用于类似的非线性试井问题。

A mathematical model for pressure transient analysis in polymer-flooding system was established,in which the shear thinning effect of non-Newtonian polymer solution is considered.The governing equations were discretized by finite volume method with a hybrid grid consisting of Cartesian meshes with radial refinement around well positions.The shut-in pressures from numerical solution were compared with those obtained with the superposition principle method.It shows that shut-in bottom-hole pressure computed with superposition principle method is much lower than the numerical result for polymer-flooding system,which indicating that the superposition principle cannot be used for pressure transient analysis in polymer-flooding system.Shut-in pressure data of an injection well in a polymer-flooding system was interpreted.It is found that the permeability obtained with superposition principle method is very small,which shows that the superposition principle method cannot be used to solve the nonlinear model for pressure transient analysis in polymer-flooding system.The numerical method is more suitable for polymer-flooding system.The conclusions are applicable to similar nonlinear problems in pressure transient analysis.