Effect of time varying fracture-skin thickness on contaminant transport in fracture-matrix coupled system

Abstract

A numerical model is developed for analyzing the effect of time varying fracture skin thickness on contaminant transport mechanism in the fractured porous media. Recent investigations by researchers in subsurface media have brought out the importance of fracture-skin formation and its effect of contaminant transport in fracture-matrix coupled system. Implicit finite difference numerical technique has been used to solve the coupled non-linear governing equations for the triple continuum model consisting of fracture, fracture-skin and the rock-matrix. A varying grid is adopted at the fracture and fracture-skin interface to capture the mass transfer at the interface. The fracture-skin thickness is assumed to increase with time and the effect of time varying fracture skin thickness on the contaminant transport mechanism is analyzed. Results suggest that the mass transfer from the fracture to the fracture-skin is high when the fracture-skin thickness is small. The contaminant concentration for both constant as well as time varying fracture-skin thickness remains the same during the initial simulation time and varies as time progresses. The time varying fracture-skin thickness has a significant effect on the contaminant concentration at larger simulation periods. The effect of time varying fracture-skin thickness on contaminant concentration reduces with increment in the initial fracture-skin thickness.