Numerical simulation of steam injection processes with solvent

In Venezuela during recent years, gas oil has been evaluated as an additive to increase steam injection process efficiency. The results of laboratory and field tests have shown a significant improvement in the production behavior. Despite these experiences, it is necessary to complement the information with results obtained from numerical simulation studies in order to know injection parameter effects, such as gas oil concentration, schemes and rates of injection, temperatures, etc., and also some mechanisms involved in the process. In this work, the results achieved in the numerical simulation of displacement tests with steam and gas oil are presented. A fully implicit 2-D thermal, three-phase compositional simulator was used to obtain all the data presented in this paper The numerical simulation results show a similar oil production performance to those obtained in the displacement tests with injection of gas oil and steam simultaneously. These results indicate rising of the production rate when the solvent concentration increases. They also reveal that the solvent co-injection scheme improves the productivity in relation to the gas oil pre-injection at low temperature. However, when gas oil is pre-injected at higher temperature, the oil production performance is similar to the co-injection scheme performance. This can attributemore » to the favorable temperature effect on the diffusion mechanisms. On the other hand, an increase of the gas oil injection rate causes a productivity reduction. In addition, the gas oil capacity to remove more viscous fractions than the original crude was verified. It was determined that the gas oil light fraction volatilization contributes to the process improvement. In general, these results confirm the benefit of using solvent and contribute to the understanding of process mechanisms.« less