TOUGH+Hydrate v1.0 User's Manual: A Code for the Simulation of System Behavior in Hydrate-Bearing Geologic Media

Abstract

TOUGH+HYDRATE v1.0 is a new code for the simulation of the behavior of hydrate-bearing geologic systems. By solving the coupled equations of mass and heat balance, TOUGH+HYDRATE can model the non-isothermal gas release, phase behavior and flow of fluids and heat under conditions typical of common natural CH 4 -hydrate deposits (i.e., in the permafrost and in deep ocean sediments) in complex geological media at any scale (from laboratory to reservoir) at which Darcy's law is valid. TOUGH+HYDRATE v1.0 includes both an equilibrium and a kinetic model of hydrate formation and dissociation. The model accounts for heat and up to four mass components, i.e., water, CH 4 , hydrate, and water-soluble inhibitors such as salts or alcohols. These are partitioned among four possible phases (gas phase, liquid phase, ice phase and hydrate phase). Hydrate dissociation or formation, phase changes and the corresponding thermal effects are fully described, as are the effects of inhibitors. The model can describe all possible hydrate dissociation mechanisms, i.e., depressurization, thermal stimulation, salting-out effects and inhibitor-induced effects.TOUGH+HYDRATE is the first member of TOUGH+, the successor to the TOUGH2 [Pruess et al., 1991] family of codes for multi-component, multiphase fluid and heat flow developed at the Lawrence Berkeley National Laboratory. It is written in standard FORTRAN 95, and can be run on any computational platform (workstation, PC, Macintosh) for which such compilers are available. iv v

Modeling Pure Methane Hydrate Dissociation Using a Numerical Simulator from a Novel Combination of X-ray Computed Tomography and Macroscopic Data

“…17 The simulator can model the nonisothermal hydration reaction (dissociation) and the flow of water, gas, and heat in a porous medium.…”

“…Two obvious shortcomings of this approach are that (1) the skeleton of the pseudo-medium has to be sufficiently extensive to support the conventional physics of flow through porous media, and (2) The permeability of the system changes as a function of the hydrate saturation according to the model of Verma and Pruess. 26 The process for accounting for the changing absolute and relative permeability as the hydrate saturation decreases is fully described by Moridis et al 17 To account for the heterogeneity in the radial direction (see Figure 3b), we divided the sample into two separate zones characterized by different hydrate, water, and gas saturations (S H , S A and S G , respectively). The two zones were identified from CT scans, which also provided estimates of the S H , S A , and S G distributions in the two zones (see Figure 3b).…”

“…17 The properties of the gas phase (which is mostly CH 4 , with a small fraction of water vapor) are computed using the Peng-Robinson equation of state (one of the options in T+H). Methane hydrate properties such as heat capacity, thermal conductivity, density, and hydration number have been obtained from the extensive data included in Sloan and Koh.…”

“…10,11,12,13,14,15,16 In the present study, we used the TOUGH+HYDRATE (hereafter referred to as T+H) numerical simulator to model pure methane hydrate dissociation in a laboratory experiment. 17 We compared the measured and modeled transient thermal response and gas evolution from the hydrate during dissociation. The hydrate dissociation data were obtained from x-ray computed tomography analysis combined with simultaneous pressure, temperature, and gas evolution measurements during dissociation.…”

Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

“…Gas partial pressures and fugacity coefficients computed from the flow module (TMVOC) are passed to the geochemical module (-REACT) for calculating dissolved concentrations in water. The routine GASEOS (Reagan and Oldenburg, 2006;Moridis et al, 2008) was also incorporated into TMVOC_REACT for computation of gas-phase properties and fugacity coefficients in gas mixtures. This routine incorporates several standard cubic equations of state such as Redlich-Kwong (RK), Peng-Robinson (PR), and Soave-Redlich-Kwong (SRK) (e.g., Orbey and Sandler, 1998).…”