MUFITS

MUFITS is a noncommercial reservoir simulator for analysis of non-isothermal multiphase multicomponent flows in porous media. The simulator is designed for parallel compositional simulations using both laptops and supercomputers. MUFITS can accommodate geologic, petrophysic and thermophysic data of the real-world complexity.

MUFITS has several EOS modules for prediction PVT properties of reservoir fluids:

• BINMIXT module for modelling nonisothermal three-phase flows of binary mixtures. The properties are specified by the thermodynamic potential of the mixture, which is calculated before hydrodynamic simulations. The potential is used in conditional extremum problem, which corresponds to the entropy maximum condition in thermodynamic equilibrium. By using this formulation, MUFITS can determine single-, two-, and three-phase equilibriums of the mixture under sub- and supercritical conditions. The primary variables are the pressure, the mixture total enthalpy and the composition. The system singularities in the vicinity of critical thermodynamic conditions are eliminated if these variables are used. Therefore, the simulator can avoid dramatic timestep cuts for hydrodynamic simulations under near-critical conditions.
• BLACKOIL module for modelling petroleum reservoirs using extended Black-oil approach. The module is capable of single-phase, two-phase and three-phase flows of water, oil and hydrocarbon gas. The gas condensate option is available. This module can be used for analysis of various aspects of oil production. There are many examples of this module application.
• GASSTORE module for modelling underground CO2 storage, hydrocarbon gas storage and some geothermal scenarios. The module covers three-component three-phase flows of water, salt and gas components. The permeability reduction due to salt precipitation can be simulated.
• T2EOS1 module for modelling nonisothermal single-component flows of water and steam under subcritical thermodynamic conditions. Phase transitions between water and steam are taken into account. This module can be used in hydrothermal applications.

MUFITS can accommodate complex geological setting of the reservoir like heterogeneity, folds or faults. The simulator can load the corner-point grids commonly used in the reservoir simulation industry. The simulator can also automatically create cartesian or radial grids for academic research studies. The local grid refinement, faults and aquifer options are available among others.

The simulations can be performed in parallel using supercomputers. From the very outset of MUFITS development, the simulator was designed for parallel simulation using MPI interface. This ensured a very good scaling of the computational problems. The estimates show that up to 32 processes there is a linear acceleration of the simulations for a problem comprising several hundred thousand cel