Numerical simulation of injectivity loss in stratified reservoirs

Abstract

Injectivity loss occurs when sea water is injected in offshore fields or during reinjection of produced water that contains solid particles, oil drops and bacteria, each one with its own capability of reducing the permeability in the neighbourhood of the well. Knowledge regarding the causes of injectivity decline and its time scale is important for the prevention and remediation of this problem. We present a numerical model for water injection with retention of solid particles in a vertically stratified reservoir in a cylindrical axisymmetric geometry. The process of migration and retention of solid particles in porous media is studied through computer simulations. To do so, we apply a hydrodynamical formulation for the flow of water containing suspension particles. The numerical tools used in this work are the modified method of characteristics proposed by Douglas and Russell for the concentration of particles (suspended and retained) coupled with the mixed finite element method proposed by Raviart and Thomas for velocity and pressure. We briefly describe the method and show the numerical results. There is a strong tendency for the flow to remain confined in each layer.