Analytical Calculation of Minimum Miscibility Pressure: Comprehensive Testing and Its Application in a Quantitative Analysis of the Effect of Numerical Dispersion for Different Miscibility Development Mechanisms

Abstract

Abstract The newly developed analytical approach for calculating Minimum Miscibility Pressure (MMP) is tested using a wide range of slim tube test data involving a number of real crude oil systems. This shows that the analytical method for calculating MMP is capable of determining MMPs that are consistent with slim tube experimental data. The results indicate that this approach not only allows for rapid, accurate and objective determination of MMP for any displacement process, but also makes it possible to determine the displacement mechanisms in a quantitative fashion. The analytical method is then used to compare with coarse-grid one-dimensional compositional simulation results to investigate the effect of numerical dispersion on the determination of MMP through compositional simulation for different miscibility development mechanisms. Results show that a quantitative description of the miscibility development mechanism as a result of the analytical MMP calculation methodology is a useful indicator of the impact of numerical dispersion on recovery. It is shown that although for real crude oil systems the displacement mechanism is predominantly the combined condensing/vaporizing gas drive, the effect of numerical dispersion is more pronounced in displacements whose mechanisms are closer to the pure vaporizing gas drive. It is therefore argued in this paper that for detailed compositional analysis of miscible or near miscible gas injection processes, more care must be taken to account for the effect of numerical dispersion if the miscibility development mechanism is close to pure vaporizing gas drive.