Performance evaluation of miscible and near-miscible gas injection processes can be assessed through conventional finite difference (FD) compositional simulation. However, low-resolution compositional simulation is adversely affected by numerical dispersion and may fail to represent geological heterogeneities adequately, and high-resolution simulation is too expensive in computation time. The number of components can be reduced but at the price of less accurate representation of phase behavior.

Streamline methods offer another approach to high-resolution simulation. This paper reports results of combining an analytical, one-dimensional (1D) solution for multicomponent gas injection with a representation of flow along streamlines to capture the effects of heterogeneity. The 1D solution allows any number of components to be present in the injected gas as well as in the reservoir fluid. We report the results from combining the analytical 1D multicomponent solutions with 2D and 3D streamline simulators. A detailed comparison is given between the results of conventional FD simulation and the streamline approach. The comparison demonstrates that the CPU time requirement used in evaluation studies can be reduced significantly while at the same time reducing the adverse effects of numerical dispersion.

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