EOS7MG-A new TOUGH3 module for multiple gas mixture simulation

Recently, we have developed a new TOUGH3  EOS modules named ESO7MG. It is designed for modeling water, brine, and multiple gas species and their mixtures including hydrogen in subsurface multiphase flow systems. The module allows mixtures of as many as three gas components selected from a list of available gases (CH4, C2H6, C3H8, H2S, CO2, N2, NO2, H2, and AIR). Key features of the new module include:

(1)   A flexible number of overall mass components (3-5) depending on user needs to lower computation time. The model system can have single-phase (gas or liquid) or two-phase regions, but it must have at least one gas component and at most three gas components (gas components can be fully dissolved in the aqueous phase depending on P-T-X conditions). Computational burden is lower with fewer mass conservation equations (fewer gas components).

(2)   The use of gas-phase mass fraction as a primary variable instead of liquid-phase mass fraction avoids the need for the iterative solution of gas solubility used in EOS7C.

(3)   A choice of gases relevant to subsurface energy applications: CH4, C2H6, C3H8, H2S, CO2, N2, O2, H2, and AIR.

(4)   Implementation of the viscosity model of Quinones et al. (2000) for accurate viscosities of H2 mixtures. If H2 exists in the simulation, the Quinones et al. method is automatically used as the default. Calibration has been done for viscosity calculation 

(5)   EOS7MG allows different types of initial conditions for user convenience.

(6)   As part of TOUGH3, all of the functionality of TOUGH3 is available including parallel computing capabilities.   

EOS7MG is free for the users with TOUGH3 license. It will be distributed within the TOUGH3 V1.11.