A multi-purpose model is developed for simulating primary, secondary, and some of the tertiary recovery processes. The simulator models the isothermal flow of oil, water, and gas in porous media in two dimensions using either rectangular or radial coordinates.

Initially, partial differential equations describing the fluid flow are approximated using finite difference technique and the resulting system of equations are solved simultaneously via alternating direction implicit procedure. The transmissibilities are calculated using explicit, semi-implicit or fully implicit formulations. Although block centered grids are used for rectangular system, a mesh centered grid is employed in the case of radial system which yields in better representation of the well block pressures. Injected fluids are tracked separately but they are accounted for within all phases using mixing parameters that empirically predict the incomplete mixing within a block. In the case of polymer injection, the modified Blake-Kozeny4  equation is used in the representation of the viscoelastic behavior of the injected fluid in the pseudoplastic region. The stripping of polymer from the injected fluid due to adsorption is represented as a function of polymer and rock properties.

A fully implicit well formulation is used where well block pressure was solved simultaneously. Multiple wells with different injection and production schemes are included in the model. In the case of rectangular coordinates, an infinite conductivity fracture is coupled with the well block.

An automatic time step selector is implemented to reduce the time truncation errors as well as reducing the computational costs. The property package used different techniques such as linear interpolation, least squares, or cubic splines for predicting fluid properties or the user supplied functions are used.

The simulator is tested using published data for several options against existing models and results are found to be in good agreement.

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