Investigating the relative permeability behavior in presence of capillary effects in composite core systems

Abstract

Successful designs for an injection process to improve reservoir recovery seek more accurate values of saturation dependent functions, including relative permeability curves. The ignorance on underlying heterogeneity (e.g. layering) might lead to inaccurate predicting of flow behavior in layered heterogeneous porous media. Analysis of experimental core flood results in composite core systems (the system) along with numerical simulation at the core scale can provide an insight into this problem, especially when the capillary effects are present. In this study unsteady state two phase displacements have been conducted on the system with different internal arrangements. The main contribution is to compare the relative permeability behavior of composite system against the results of single cores using both explicit as well as implicit methods in the presence of capillary forces. The experimental results showed that fluid flow behavior in the system significantly differs from of the flow characteristics in single cores. The controlling parameters on the relative permeability behavior of whole system include the internal arrangement, permeability values and length of cores. Simulation results showed that in the case of descending ordering (of permeability), the relative permeability of the system is almost independent of the individual cores' length. In contrast, in the case of ascending ordering of core permeability values, it strongly depends on the core structure. When the capillary pressure and relative permeability curves of individual cores are the same, simulation results showed that Huppler arrangement gives the relative permeability of the system close to the behavior of the individual cores. A new correlation set has been developed which predict the relative permeability of whole system based on the relative permeability, internal arrangements, and lengths of single cores with a reasonable agreement.