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

摘要

The newly developed analytical approach for calculatingMinimum Miscibility Pressure (MMP) is tested using a widerange of slim tube test data involving a number of real crudeoil systems. This shows that the analytical method forcalculating MMP is capable of determining MMPs that areconsistent with slim tube experimental data. The resultsindicate that this approach not only allows for rapid, accurateand objective determination of MMP for any displacementprocess, but also makes it possible to determine thedisplacement mechanisms in a quantitative fashion.The analytical method is then used to compare withcoarse-grid one-dimensional compositional simulation resultsto investigate the effect of numerical dispersion on thedetermination of MMP through compositional simulation fordifferent miscibility development mechanisms. Results showthat a quantitative description of the miscibility developmentmechanism as a result of the analytical MMP calculationmethodology is a useful indicator of the impact of numericaldispersion on recovery.It is shown that although for real crude oil systems thedisplacement mechanism is predominantly the combinedcondensing/vaporizing gas drive, the effect of numericaldispersion is more pronounced in displacements whosemechanisms are closer to the pure vaporizing gas drive. It istherefore argued in this paper that for detailed compositionalanalysis of miscible or near miscible gas injection processes,more care must be taken to account for the effect of numericaldispersion if the miscibility development mechanism is closeto pure vaporizing gas drive.