饱和多孔介质中胶体运移模拟方法研究进展

Review on modeling the transport and retention of colloids in saturated porous media

阐述了国内外针对胶体在饱和多孔介质中运移模拟方法的研究进展:胶体在多孔介质中由于对流和弥散作用发生运移,而由于表面沉积和筛滤作用滞留在多孔介质中,通常采用含有滞留项的对流弥散方程对胶体的运移行为进行宏观描述,并通过拟合得到胶体运移和滞留的宏观参数,但是对流弥散方程是对试验曲线的宏观描述,无法解释其背后的微观机理;胶体的运移和滞留作用由胶体的微观受力决定,包括胶体在水中的布朗运动和有效重力,胶体-胶体/胶体-固相表面之间的相互作用以及流场作用在胶体上的力3个部分;为了实现从微观受力到宏观参数的升尺度计算,研究者们提出了胶体过滤理论及其后续的修正方法对沉积速率等宏观参数进行预测,然而现有方法通常基于简化的流场,忽略了多孔介质复杂孔隙结构和表面特性的影响;孔隙结构模型是多孔介质孔隙结构的简化模型,基于该模型能够从胶体在多孔介质中的微观力学分析出发,预测胶体的宏观运移行为,然而已有研究中尚未全面的考虑胶体在多孔介质中运移和滞留的多种作用.本文总结了该领域待解决的问题,包括建立考虑微观机理的对流弥散方程,发展考虑多孔介质孔隙结构的胶体过滤理论以及完善基于孔隙结构模型的胶体运移模拟方法.

The research progress on the modeling of colloid transport and retention in saturated porous media is reviewed.Colloids transport in porous media due to convection and dispersion but retain in porous media due to surface deposition and straining.The advection dispersion equation with retention term can effectively describe the form of the breakthrough curves and the retention profiles in the one-dimensional column tests,and the macroscopic transport and retention parameters of the colloid can be obtained through fitting.However,the convection dispersion equation is a macroscopic description of the test curves and cannot explain the microscopic mechanism behind them.The micromechanical analysis of colloid decides its transport and retention behavior,including the Brownian motion of the colloid itself,the interaction between colloid-colloid/colloid-solid surface,and the force of the flow field acting on the colloid.Macroscopic parameters of colloidal movement in porous media can be predicted based on colloidal filtration theory and its subsequent modification methods.However,existing methods are usually based on a simplified structure and internal flow field of porous media,ignoring the influence of pore structure and surface characteristics of porous media.The pore structure model is a simplified model of porous media pore structure.Based on this model,the macroscopic transport and retention behavior of colloids can be predicted considering the micromechanical analysis of colloids.However,the various effects of colloid transport and retention in porous media have not been fully considered in current studies.The problems to be solved in this field are summarized,including the establishment of convection dispersion equation considering microscopic mechanism,the development of colloid filtration theory considering pore structure of porous media,and the improvement of colloid transport and retention simulation method based on pore structure model.