Tree-dimensional Crude Oil Flow Simulation through Rough-walled Fractures for Evaluating the Classic Geometrical Equations

This paper investigates the crude oil flow through open and rough-walled fractures. The aim of this paper is to evaluate the effects of surface roughness and spatial arrangement of aperture segment on fluid flow phenomenon through rough-walled fractures. In addition, the validity of classic geometrical equations of cubic law correction was explored by comparing the output results of numerical simulations (in terms of permeability). To reach this goal, the crude oil flow through three-dimensional rough-walled fractures was numerically simulated by simultaneous solving of Navier-Stokes and mass conservation equations and utilizing FLUENTTM computational software. The numerical crude oil flow simulation was performed for six different three-dimensional geometrical models of fractures whit different roughness and aperture arrangements and constant porosity. The results of fluid flow simulation were analyzed with different points of view and then compared with the classic geometrical equations of cubic law correction. The results of this study show that (i) for the open fractures, the effects of roughness on the pressure lose is higher than spatial arrangement of aperture segment, (ii) due to the nonlinearity of flow, the permeability of fractures decreases by increasing the Reynolds number, and (iii) with the classic geometrical equations of cubic law correction encounter with about 5 to 35% error and the accuracy of these equations will be decrease by decrease the permeability of fractures or increase of roughness and spatial variability of aperture. These findings prove useful in proper understanding of crude oil flow in fractures, or inclusions in computational simulation of large-scale flow in fractured petroleum reservoirs.