Streamline methods, in which fluid is transported along the streamlines instead of the finite difference grid, are widely used d in the oil industry. Larger time steps and higher spatial resolution can be achieved in streamline simulations. 3D flow problem is decoupled into a set of 1D problems solved along streamlines, which reduces the simulation time and suppresses the numerical dispersion. However, finite-difference reservoir simulation is widely used for solving large-scale multiphase displacement problems, streamline proved to be a faster tool for proper reservoir managment.

Proper assessment of miscible and near-miscible gas injection processes are usually carried out through conventional finite difference (FD) compositional simulation. Due to high-resolution simulation of the detailed geological model (Fine grid) is time consuming, coarse grid (Low resolution) models are normally used for testing the performance as a fast track process. Low-resolution compositional simulation is adversely affected by numerical dispersion and may fail to represent geological heterogeneities adequately. Streamline application will properly describe displacement and volumetric sweep in the fine grid model that capturing all reservoir heterogeneity.

Streamline computations assume incompressible fluids, and therefore they are not usually used for reservoir simulation of gas injection processes and for depletion studies below the bubble point. This paper presents the results of investigating the use of streamline techniques in gas displacement processes. A detailed comparison is given between the results of conventional FD simulation and the streamline approach. The comparison demonstrates that streamline simulation can be used in gas displacement processes under certain conditions. In such cases, the CPU time requirements and numerical dispersion can be reduced significantly while allowing the engineer to use a finely gridded model capturing the heterogeneity of the reservoir.

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