Study On Total Trapping Number And Wettability In SEAR Process For DNAPL Remediation

With the development of petrochemical industry,DNAPL caused serious environmental pollution problems.At present,surfactant enhanced aquifer remediation(SEAR)technology has been proved to be an effective remediation method in porous media,however,there are some key problems for the use of SEAR technology to repair DNAPL in porous media.Aiming at the problems of SEAR technology,this paper is divided into two parts to discuss the problem of recontamination in the process of SEAR(Surfactant-enhanced aquifer remediation)and the influence of wettability on migration and distribution of DNAPL in porous media.The following are the main contents of two aspects:(1)SEAR is applicable to the remediation of DNAPL,and the remedy mechanism is mainly divided into solubilization and mobilization,among.During the mobilization process,quantitative evaluation of DNAPL recovery behavior in porous media is very important.In this paper,UTCHEM,which is a multiphase numerical model,is used to explore the influence of flow velocity on DNAPL mobilization behavior.The total trapping number is used for evaluating the influence of flow velocity quantitatively.Results shows that the total trapping number can describe the process of surfactant flood and the efficiency of the DNAPL recovery with relative accuracy as the flow velocity changed.The angle,which was defined as the ratio of bond number and capillary number(the two components of the total number),can be used to estimate the path of residual DNAPL's mobilization behavior with relative accuracy under the condition of different flow velocity.(2)The migration and distribution of DNAPL in the underground medium is influenced by many factors,such as velocity,permeability,heterogeneity of the medium,etc..The influence of wettability has not attracted enough attention.The presence of artificial surfactants may affect the migration and distribution of DNAPL by changing wettability.In this paper,the effects of different background solutions(pure water and two different concentrations of Tween 80 solution)on the migration behavior of DNAPL is investigated by means of experiments and numerical simulation.In the experiment,the saturation of DNAPL at different time is revealed by the light penetration method,and the multiphase numerical model UTCHEM is used to simulate the migration process of DNAPL.The comparison of the experimental results and the simulation results and the comparison of the first order moments and the two moments respectively proved that the simulation results are in good agreement with the experimental results.Through the analysis and comparison of the moment saturation solution under the condition of three background analysis,show that the Tween 80 solution will weaken the vertical migration of DNAPL,enhance the level of the direction of migration,and high saturation area ratio increases.