Features & Capabilities

TOUGH+ solves mass and energy balance equations that describe fluid and heat flow in general multiphase, multicomponent, porous-media systems. TOUGH+ can model the following processes and phenomena in geologic systems:

  1. The partitioning of the mass components among the possible phases
  2. The flow of gases and liquids in geologic media
  3. The corresponding heat flow and transport
  4. Heat exchanges due to
    • Conduction
    • Advection/convection
    • Radiation
    • Latent heat related to phase changes
    • Gas and inhibitor dissolution
  5. The transport of water-soluble gases and solutes (such as salts and alcohols, if included in the properties model), accounting for advection and molecular diffusion

When using the HYDRATE properties module:

  1. Equilibrium or kinetic hydration reaction
  2. The effects of water-soluble inhibitors on the hydrate behavior
  3. Any method of hydrate dissociation (i.e., depressurization, thermal stimulation and inhibitor effects), and combinations thereof

A deliberate effort was made to keep the simplifying assumptions involved in the development of the underlying physical, thermodynamic and mathematical model to a minimum. The assumptions used include:

  • Darcy's law is valid in the simulated domain under the conditions of the study
  • In the transport of dissolved gases and inhibitors, mechanical dispersion is small compared to advection
  • The movement of the geologic medium (for example soil heaving while freezing) is not described, and the effects on pressure are accommodated through a relatively high pore compressibility of the geologic medium (external coupling to external geomechanics software is supported)
  • Dissolved salts do not precipitate as their concentration increases; consequently, the aqueous phase is not allowed to disappear when salts are present
  • The concentration of the dissolved species is such that it does not affect the thermophysical properties of the aqueous phase
  • The pressure P remains below 100 MPa (14,500 psi).

A detailed description of the constitutive equations used in TOUGH+ can be found in the TOUGH+ users manual.

TOUGH+ maintains a great deal of backward compatibility with TOUGH2 input files and input conventions, while also providing new user features such as dynamic memory allocation and modern memory management, enhanced meshing capabilities, namelist-based input designations, improved labeling of input and output files, and the option of coupling to commercial geomechanical simulators.

TOUGH+ has been validated and verified through comparison to different analytical and numerical solutions, laboratory results, and data from field-scale experiments.