An in-situ combustion simulator for enhanced oil recovery

Abstract

A multi-dimensional three phase flow simulator is written tosimulate the process of in-situ combustion. It has six components(oxygen, inert gas, a light oil, a heavy oil, water, and coke). Theinert gas consists of all the noncondensible gases other than oxygen.The vaporization and condensation of both water and oil is governed byvapour-liquid equilibria, using temperature and pressure dependentequilibrium coefficients. Splitting of the oil into fractions is doneto include the distillation effect.The model includes four chemical reactions. These represent inturn the formation of coke from the heavy oil, the oxidation of thecoke, and the oxidation of the light and the heavy oil. Heattransport is assumed to take place by convection and conduction. Theeffects of gravity, capillary pressure between any two fluid phases,and heat losses to the surrounding rock via conduction are alsoincluded.The model is validated using the ISCOM simulator. This has beencarried out by comparing the results from the present simulator withthese from similar calculations performed using the ISCOM simulator.ISCOM is a fully implicit multi-dimensional finite difference generalthermal simulator developed by the computing modelling group (CMG) atCalgary. This comparison is needed in order to establish confidenceIn the predictive capability of the present model for a particularreservoir.In addition, a comprehensive study of the effect of the maininput parameters on the performance characteristics of the in-situcombustion process is carried out. This study is made in order toindicate which data are "important" in the sense of having asignificant influence on the performance characteristics of theprocess and to test the robustness of the program to changes in theinput parameters