残留聚合物再利用数值模拟研究

Numerical simulation of the residual polymer reutilization

为了描述残留聚合物再利用过程中絮凝剂和絮凝体在地下的运移规律和渗流特征,在化学驱模型的基础上,考虑了固体组分的滞留以及对孔隙度和渗透率的影响,建立了残留聚合物再利用调剖的三维两相五组分数学模型。分别对模型各组分方程进行了差分离散,最后转化成线性方程组进行求解,其中在对絮凝剂和絮凝体质量守恒方程求解时,利用算子分离技术将方程转化为抛物线方程和双曲线方程进行求解,提高了计算的精度和速度。建立了概念模型,对影响残留聚合物再利用调剖效果的地层参数和注入参数进行了敏感性分析。结果表明,随着渗透率级差的增大,残留聚合物再利用提高采收率的幅度先增加后减小;注絮凝剂越早、注入量及注入浓度越大,残留聚合物再利用提高采收率效果越好。

The present paper,based on chemistry flooding model and integrated with the detention of solid constituents and its influence on porosity and permeability,deciphered underground migration law and vadose characteristics of flocculant and floc units in the process of residual polymer reutilization by means of establishing a three-dimension,two-phase and five-component mathematical model for simulating profile control of residual polymer reutilization. An infinite difference method was used to discretize equations of each component in the model,respectively and then a system of linear equations was obtained. The mass-conservation equation of flocculants and floc-units was split into a parabolic equation for diffusion and a hyperbolic equation for convection by means of operator-splitting algorithms. This approach improved the precision and speed of calculations. The paper introduced a number of conceptual models and carried out sensitivity analyses on formation parameters and injection parameters that influence the effect of profile control on residual polymer reutilization. The results indicated that with the increase of permeability grade,the extent of residual polymer reutilization for the recovery enhancement increased first and then decreased,and that the earlier the flocculant injection,the bigger the quantity of injected flocculants and the higher the concentration of injected flocculants,the better the effect of residual polymer reutilization for the recovery enhancement.