Sim Pro uses the black oil model. In other words, the simulator can simulate the simultaneous flow of oil, gas and water phases considering solution/release of gas in/from the oil phase. The flow equations are discretized using the finite difference method on block-centered grid. The equations are discretized using fully implicit method for single phase flow and iterative IMPES method for multi-phase .

Sim Pro can handle 3D reservoirs with complicated geometries using active/inactive cell indexing. The wells can be completed selectively in the target reservoir layers for enhanced production of the reservoir. The injection/production wells can be controlled in various conditions i.e.constant bottom hole pressure, constant phase/liquid/total production rate at reservoir/standard condition, constant injection rate at reservoir/surface condition etc. The Peaceman method is used to model the wells.

The discretization of the flow equations result into a system of linear equations.The solution of this equation is the most time consuming part of the simulator.Here, the preconditioned conjugate gradient method is used. This method is improved such that it fully utilizes the properties of the resultant coefficient matrix and hence leading to a faster convergence rate.