The development, testing and application of a multipurpose compositional simulator

In this study a new multipurpose compositional model for petroleum reservoirs has been developed. The model is capable of simulating isothermal and nonisothermal, secondary or tertiary recovery processes, as well as condensate reservoirs where mass transfer of components between phases is significant. The simulator models the flow of up to four phases in porous media in three-dimensional rectangular coordinates.; The present compositional model utilizes either Soave-Redlich-Kwong (1972) or Peng-Robinson (1976) equations of state to describe the phase behavior of the system in lieu of predetermined equilibrium constants. The phase equilibria package is capable of handling coexisting liquid phases and is equipped with a robust critical point determination technique which is used in identifying the phases obtained under the existing temperature and pressure conditions. The tuning of the interaction parameters and the characterization of the C{dollar}sb{lcub}7+{rcub}{dollar} fraction is accomplished via a linear programming routine. An algorithm that can be utilized in refining the tuned interaction parameters and/or the C{dollar}sb{lcub}7+{rcub}{dollar} fraction critical properties is also introduced. The fluid properties are determined via various correlations given in the literature.; The partial differential equations describing the fluid flow were approximated using the finite difference technique and the resulting system of equations was solved simultaneously. Newton-Raphson procedure was utilized for this purpose and the derivatives of the flow and the constraint equations with respect to the unknowns were calculated numerically. These derivatives constitute the entries of the Jacobian matrix and the resulting Jacobian matrix was solved by using a direct solver.; A fully implicit well formulation was used and well-block pressure was solved in each iteration level. Model can accommodate multiple wells with variable and/or constant injection and production schemes.; The simulator was tested using published data for several options. Results were found to be in good agreement. Also, various sensitivity checks were made by varying different parameters in order to test the model under different conditions. Nonisothermal case was tested by varying steam quality and the temperature profiles were observed to be consistent with the theory. Also, the influence of the grid size on numerical dispersion is investigated. The proposed simulator is tested by varying the injection rate of CO{dollar}sb2{dollar} and an investigation is carried out to observe the effect of time step size in the results. Fully implicit character of the proposed model is found to be an advantage in that bigger time step sizes could be accommodated.