An Experimental Investigation of Fracture Impacts on the Dispersion of Miscible Displacement Processes: Qualitative Analysis

Abstract

Dispersion phenomena of miscible displacement processes conducted on porous media have been investigated by many researchers in different engineering field in the past 50 years. In microscopic scale, the pore size distribution has been shown to cause dispersion of two miscible displacement fluids flowing through laboratory core scale. In field scale, the heterogeneity of reservoir formation has been shown to be a main cause of dispersion. One of the heterogeneities of reservoir formation is the presence of networks of fractures. The roles of network fractures on dispersion have not been investigated in enhanced oil recovery miscible displacement processes. In this work, the effect of fractures on dispersion was investigated by conducting miscible displacement laboratory tests on micromodels. The tests were performed under two different injection rates with two different fracture orientations. The results show that breakthrough time is reduced when the fracture is present in the micromodel. Higher pore volume injection of displacing fluid is needed for fractured patterns to reach normalized concentration of one in comparison with the homogeneous one. The experimental results suggest that the breakthrough curve of the fractured system has three distinct regions in comparison with the homogeneous system. Also, the results show that a system with a fracture perpendicular to the flow direction acts as a dead end pore system.