渗透率空间变异性对重非水相流体运移的影响

摘要

A multiphase (including NAPL-aqueous-gas) model is established to investigate the migration of dense non-aqueous phase liquid (DNAPLs) in unsaturated-saturated porous media. Four scenarios of stochastic permeability fields with different spatial variation are generated using the Karhunen-Loeve expansion method. DNAPLs sinfiltration and spreading behavior is further simulated based on the four scenarios of permeability fields. The DNAPLs saturation and its spatial moments are analyzed to investigate the impacts of the spatial variation of permeability on DNAPLs migration. Numerical results show that the variation of DNAPLs saturation is increased with the enlargement of the variation of permeability. The migration of DNAPLs sis strongly influenced by the preferential pathway which controls the migration paths and the final distribution of DNAPLs. Moreover, the migration of DNAPLs is affected by the permeability anisotropy, which reduces the vertical velocity of DNAPLs plume.%文中针对多孔介质中水、气和非水相流体的多相流运移特点，建立了由包气带至饱和带的NAPLs-水-气三相流模型。用Karhunen-Loeve展开方法构建4个空间变异性不同的渗透率随机场。在此基础上，分别模拟4种情景重非水相流体（DNAPLs）的泄漏运移过程。通过分析DNAPLs饱和度的空间分布以及其空间矩随时间的变化来探讨渗透率空间变异性对DNAPLs运移的影响。结果显示，随着渗透率空间变异性的增强，DNAPLs饱和度的空间变异性增大。渗透率场中的优势通道对DNAPLs运移有着显著影响，直接决定DNAPLs的运移路径和饱和度分布。渗透率场的各向异性降低了DNAPLs在垂向上的运移速度，影响污染羽的形态。