GPAS

GPAS is a three-dimensional multicomponent multiphase fully implicit finite difference and finite volume compositional simulator with the parallel processing capability. It includes both a cubic equation of state model for the hydrocarbon phase behavior and Hand's rule for the surfactant/oil/brine phase behavior. The Peng-Robinson EOS is used for hydrocarbon phase behavior calculations. The aqueous species in the chemical model include surfactant, polymer, and salt. The physical property models include surfactant/oil/brine phase behavior, interfacial tension, viscosity, adsorption, and relative permeability as a function of trapping number.

The linear solvers from PETSc package developed at Argonne National Laboratory are used for the solution of underlying linear equations. The computational framework supports parallel computations on distributed memory computers using message passing. On multiprocessor computers, the reservoir domain is divided into several subdomains equal to the number of processors allocated for the run. The computations associated with each of these subdomains are distributed to individual processors. The communication between the processors is based on the message passing interface (MPI). Some of the applications of GPAS are:

• Water flooding
• Miscible gas flooding
• Immiscible gas flooding
• Carbon sequestration
• Tracers
• Surfactant/polymer flooding
• Steam flooding