非均质裂隙介质中重非水相流体运移

Study on the migration of dense non-aqueous phase liquids in heterogeneous fractured media

由于裂隙介质具有强烈非均质性,使得重非水相流体(DNAPLs)在裂隙介质中的运移行为较孔隙介质更为复杂。基于指示模拟算法模拟裂隙介质的二元变量(粗糙面接触和裂隙开口),综合模拟退火算法构建裂隙渗透率随机场。采用T2VOC模拟DNAPLs在裂隙介质的运移,探讨粗糙面接触的相关长度、各向异性比、倾角以及非均质性程度对DNAPLs运移分布的影响。数值分析结果表明,粗糙面接触的相关性越差,DNAPLs污染范围越大;粗糙面接触的各向异性比和倾角增大,将导致更多DNAPLs残留;而相关长度和各向异性比增大以及倾角减小,都会引起DNAPLs锋面运移速率增大;随着渗透率非均质性增强,会导致局部粗糙面接触上蓄积的DNAPLs饱和度增大,运移速率减小。

Due to the strong heterogeneity of fractured media, the migration behavior of Dense Non-Aqueous Phase Liquids （hereafter referred to as DNAPLs） in fractured media is more complicated than in pore media. Binary variables of fractured media are initially simulated using the indicator simulation and finally modified with simulated annealing algorithm to generate the stochastic permeability fields （SPF）. By simulating the migration of DNAPLs in fractured media with the T2VOC, we can study the effects of correlation length, anisotropy ratio, inclination of asperity contacts and degree of heterogeneity on the migration and distribution of DNAPLs. Numerical analysis results suggest that a worse correlation among adjacent asperity contacts leads to a larger pollution scope of DNAPLs; a larger anisotropy ratio and inclination lead to more residual DNAPLs; with increasing correlation length and anisotropy ratio as well as decreasing inclination, the front surface migration rate of DNAPLs increases; and the increasing heterogeneity of permeability causes an increasing saturation of DNAPLs accumulated in local asperity contacts, and a decreasing migration rate.