Investigation of grid orientation in a two-dimensional, compositional, three-phase steam model

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A new three-phase steamflood numerical model has been developed. It is fully implicit with the Jacobian being calculated analytically. The model can operate in one and two dimensions, compositional and noncompositional modes with the choice of block-centered or pointdistributed grid systems employing five-point or nine-point finite difference schemes. Two different approaches have been employed and tested for their ability to remove the effect of grid orientation in steamflood simulation. The nine-point finite difference scheme reduces the grid orientation effects dramatically while the harmonic total mobility scheme is demonstrated to aggravate the problem rather than alleviate it. The applicability of the two-point upstream mobility in steamflood simulation has been investigated. It has been shown that the twopoint upstream mobility weighting may not be valid for thermal process simulators. The results of grid size and time step sensitivity analyses show that the time - pore volume injected relationship is very sensitive to grid size and to a much lesser extent to time step size. Sensitivity studies of grid size and time step are meaningful only if each is carried out while the other variable has been chosen to minimize the truncation error associated with it. The effects of well model, heat loss, and gas hysteresis on performance parameters and primary variables are also presented and discussed. Several side benefits have resulted from this investigation. These are: 1. A novel method of solution has been developed. It offers significant reductions in both storage and computational requirements for problems with large number of grid blocks. 2. A one-problem formulation method has been developed. It involves the introduction of new pseudo physical equilibrium constants. 3. A new implicit injection scheme which takes into account the effect of steam flashing on injectivity has been developed. 4. Equations for the well geometric factor in the well model f or a corner well block have been derived. 5. An analytical solution for the rate of heat loss to the surrounding formations has been developed.
Bibliography: p. 271-275.
Abou-Kassem, J. H. (1981). Investigation of grid orientation in a two-dimensional, compositional, three-phase steam model (Unpublished doctoral thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/12433