黏弹性聚合物驱油藏渗流规律及试井模型探讨

实验测定了不同浓度下高分子聚丙烯酰胺溶液在岩芯和流变仪中的流变性，证实了其在多孔介质中流动时存在“弹性”，且在中等剪切速率范围内（0.1～100.0 s−1）符合非牛顿幂律渗流模式。基于实验取得的认识，利用黏弹性本构方程表征聚合物溶液有效黏度，建立了黏弹性聚合物驱油藏的不稳定渗流数学模型，利用有限差分方法求得数值解，研制了相应的无因次试井图版，并对实测试井资料进行了拟合解释，探讨了弹性对聚合物驱油藏试井曲线形态的影响。研究表明，弹性虽然会造成近井地层压力大幅上升，但几乎不改变试井曲线形态。因而，在黏弹性聚合物驱油藏试井分析中，可以忽略弹性的影响，应用非牛顿幂律试井模型求取解释参数。

Seepage Flow and Well Test Model for Viscous-Elastic Polymer#br#Flooding Reservoir

The rheological behaviors of high molecular polyacrylamide（HPAM）solution in porous media and rheometer weremeasured in experiments，which demonstrated the existence of viscoelasticity in polymer flooding process，and it complied withnon-Newtonian power-law seepage pattern within the scope of medium shear rate（0.1～100.0 s−1）. Based on the establishedviscous-elastic constitutive equation related to varying cross-section throat model，effective viscosity of polymer solution wasexpressed as the sum of shear viscosity and elastic viscosity，the mathematical model for transient flow in viscous-elastic polymerflooding reservoir was established and solved by finite difference method to acquire numerical solution，then dimensionlesswell test curves were developed. The effect of viscoelasticity on the shape of well test curves for viscous-elastic polymer floodingreservoir was then discussed，by comparing theoretical with realistic well test curves. The results show that the existenceof elasticity causes significant rise of formation pressure near polymer-injection well，but hardly changes the shape of well testcurves. Therefore，it is feasible to ignore the effect of elasticity and acquire parameters by adopting well test models based onnon-Newtonian power-law flow for viscous-elastic polymer flooding reservoir.