Heterogeneity Of Porous Media And Its Effect On Solute Transport

In the geological environment,the heterogeneity of porous media is an important factor affecting the solute transport of groundwater.Quantitative studies of porous media heterogeneity and effects on solute transport are challenging issues in the field of geological engineering.Therefore,it is of theoretical and practical significance to study the heterogeneity of porous media and its influence on solute transport.This paper is aimed at the spatial data of porous media.Based on the theory of transition probability geostatistics,using Matlab software calculated the transition probability matrix of the medium type in different directions with fixed steps and finally proposed a method for calculating the heterogeneity index of porous media;Using the theory of variograms,we analyzed the spatial variability of permeability coefficient and put forward a method of calculating the spatial variability index.For the permeability coefficient data,in order to realize the division of the heterogeneity of porous media,we used Matlab to complete the sliding window operation.The heterogeneity of porous media determines the spaial variability of permeability coefficient,so based on the permeability coefficient the conceptual model and mathematical model of hydrogeology were established.The MODFLOW and MT3 DMS models were used to simulate the solute transport,and the spatial moments of solute transport were calculated.The influence of the heterogeneity of the permeability coefficient on the solute transport was discussed.The main results and conclusions are as follows:(1)Proposed a method for calculating the heterogeneity index of porous media under anisotropic conditions.The analysis of the examples shows that the method can compare the heterogeneity of regions from anisotropy.(2)Proposed a method for calculating the spatial variability index of permeability coefficient.The results of the examples show that: When the size of the area is fixed and the variance is different,combined with the examples,it is found that the spatial variability index has an increasing trend compared with the variance and the former has a small increase,which is in line with the solute transport simulation results and the spatial moment change trend;Combined with the examples,to some extent,the spatial variation index can compare regional heterogeneity from an anisotropy perspective;When the size of the region is fixed and the variance is approximated,combined with the spatial moment analysis of the solute transport in the study,the spatial variability index is more suitable for characterizing the heterogeneity of the medium than the variance;The spatial variability index has certain applicability in the case of regional size change and variance approximation;Based on the spatial variability index,the regional heterogeneity is divided.