T2SOLV: An enhanced package of solvers for the TOUGH2 family of reservoir simulation codes

Abstract

T2SOLV is an enhanced package of matrix solvers for the TOUGH2 family of codes. T2SOLV includes all the Preconditioned Conjugate Gradient (PCG) solvers used in T2CG1, the current solver package, as well as LUBAND, a new direct solver, and DLUSTB, a PCG solver based on the BiCGSTAB method. Additionally, T2SOLV includes the D4 grid numbering scheme and two sets of preprocessors. Results from test problems indicate that LUBAND is faster, more reliable and requires less storage than MA28, the current direct solver. BiCGSTAB solver is shown to be superior to the other PCG methods in T2SOLV. Finally, the preprocessors improve the performance of the PCG solvers and allow the solution of previously intractable problems. TOUGH2 is capable of modeling most of the processes arising in the natural state of geothermal reservoirs and in response to production and injection operations. It can handle the appearance and disappearance of liquid and vapor phases, boiling and condensation, multiphase flow due to pressure, gravity, and capillary forces, vapor adsorption with vapor pressure lowering, heat conduction, and heat exchange between rocks and fluids. It is applicable to flow systems of arbitrary geometry from one to three dimensions, and has special provisions for flow in fractured-porous media.