考虑扩散和吸附作用的聚合物驱替过程渗流数值模拟

采用显式求解饱和度、隐式求解浓度的思路,对考虑扩散和吸附作用的聚合物驱替过程渗流模型进行了数值求解.饱和度方程求解应用了显式全变差递减(TVD)法;浓度方程求解过程中,空间项离散采用Crank Nicolson差分格式,时间项变量进行拟线性处理,保证了计算的稳定性.通过与解析解对比,验证了该方法的有效性.计算实例分析表明,扩散使聚合物在溶液中稀释,导致浓度传播分散;吸附使聚合物损耗,导致浓度传播滞后.同时,计算结果直观反映了聚合物驱重要的"油墙"形成机理.在段塞注入情况下,原油富集区在出口端的突破是介于聚合物浓度前缘突破和聚合物浓度峰值突破之间.

Numerical Simulation of Polymer Flooding with Dispersion and Adsorption

By using explicit saturation and implicit concentration methods,numerical solution is presented to the polymer drive model characterizing dispersion and adsorption of polymer solution flowing through a porous medium.Saturation equation is solved by using an explicit total variation diminishing(TVD)method.To ensure the stability of concentration equation calculation,Crank-Nicolson difference format is used in spatial discretization,and variable is quasi-linear disposed in temporal discretization.The validity of the method presented is verified by comparison with analytic solutions.The calculated example indicates that dispersion causes dilution and dissipation of polymer solutions,and adsorption results in a loss,thus leading to lagging of concentration propagation.Also,the important polymer flooding mechanism- "oil block" is illustrated in the results of calculation.Under the condition of slug injection,the breakthrough time of oil enrichment zone lies between the breakthrough time of polymer concentration front and polymer concentration peak.