A Novel Approach for Analyzing the Dispersion Transport in Radial Coordinates

摘要

The finite-control volume technique is used to solve thernradial convection-dispersion differential equation. In therndispersion model presented, the dispersion coefficient isrndependent on both velocity and diffusion coefficient. Thernsolution allows analyzing the dispersion transport of a slug inrna steady radial flow from an injection well fully penetrating arnhomogeneous reservoir of uniform thickness and finite arialrnextent. Results show that the dispersive mixing zone does notrnnecessarily grow in proportion with the square root of time forrnall times, unlike for the linear displacement. Results reveal arntypical minimum of the dispersive mixing zone with time forrnradial displacement. It appears that at some radial distancernclose to the wellbore, the dimensionless mixing zonerndecreases with the square root of time since there is anrnaccumulation of the miscible slug in this particular spacerndomain. However, when the dissolution of the slug startsrntaking effect particularly at large distances away from therninjection point, the mixing zone begins to increase withrnincreasing square root of time.rnOur solution of the convection-dispersion equation in radialrncoordinates allows to estimate the optimum slug size forrnmiscible displacement projects in hydrocarbon reservoirs. Thisrnin return allows to estimate the total amount of solvent neededrnto maintain miscibility conditions at the displacement front inrnthe bulk of the reservoir, leading to better reservoirrnmanagement and to a more adequate economic forecast ofrnEOR processes.