STOMP-HYDT-KE solves nine conservation equations at each grid cell: 1) energy, 2) water mass, 3) mobile CH4 mass, 4) hydrate CH4 mass, 3) mobile CO2 mass, 4) hydrate CO2 mass, 3) mobile N2 mass, 4) hydrate N2 mass, and 9) inhibitor mass. The syntax for solution control parameters is ordered as follows:
1) Execution Mode Option
2) Operational Mode Option
3) Execution Time Period Inputs
4) Maximum Number of Time Steps
5) Fluid Diffusion Options
6) Hydrate Formation/Dissociation Parameters
7) Interfacial Averaging Options
Character string (e.g., van Genuchten, porosity, m^3/s, Roe Superbee)
Integer (no alpha characters, special characters, or punctuation) (e.g., 1, 32, 195634)
Real (decimal points and exponential notation allowed) (e.g., 0, 0.0, 1.e-12, 1.E+3, 2.345)
Keyword (exact formatting required) (e.g., file, ~Solution Control Card, binary file)
~Solution Control Card
Execution Mode Option,
Choose one Execution Mode Option
Normal,
Restart,
Restart File,Restart Filename,
HYDT-KE + Modifiers,
Operational Mode Keyword Modifiers
w/Isothermal - indicates energy equation not solved
w/Isobrine - indicates salt mass equation not solved
w/Iso-CO2 - indicates CO2 mass equation not solved
w/Iso-CH4 - indicates CH4 mass equation not solved
w/Iso-N2 - indicates N2 mass equation not solved
w/Inhibitor - indicates NaCl inhibitor effects are turned on
Number of Execution Time Periods,
Repeat for each execution time period
Choose one time-step reduction option
Execution Time periods
Execution periods refer to a period of simulation time. STOMP-HYDT-KE allows the user to specify a single or multiple execution periods. For each execution period, the user can control the initial time step, maximum time step, time step acceleration factor, maximum number of Newton-Raphson iterations, and convergence criterion independently.
Initial time
If no initial time record is read for a restart simulation, the initial time record is obtained from the restart file.Execution Time Parameters
Recommended values for the Time Step Acceleration Factor, Maximum Number of Newton-Raphson Iterations, and Convergence Criterion are 1.25, 8, and 1.e-06, respectively. Except under special circumstances, it is not recommended to change the value for the Convergence Criterion from its recommended value. This value has proven through numerous applications to achieve a good balance between accuracy and execution speed.
Execution Time Step Controls
Two additional solution controls can be specified for each Execution Period input line: 1) the minimum time step, and 2) the time-step cut factor. These optional solution controls must be specified together. The minimum-time-step parameter sets the minimum time step for an execution period. Without this control, STOMP-HYDT-KE quits after four time-step reductions. Cyclic injection well schedules can yield simulations that execute with large time steps during steady injection periods, but require small time steps during the injection startup. The minimum-time-step parameter allows the code to cut the time step to the minimum value before quitting. The time-step cut factor is set to 0.2 by default, which means that time steps are cut to 20% of their value when a convergence failure occurs. Execution performance can be improved for some simulations by altering this factor.
Maximum Number of Time Steps,
Zero Time Step Simuations
Choose one
Variable Aqueous Diffusion,
Constant Aqueous Diffusion, Constant coefficient,
Zero Aqueous Diffusion ,
Choose one
Variable Gas Diffusion,
Constant Gas Diffusion, Constant coefficient,
Zero Gas Diffusion ,
Choose one
Variable Nonaqueous Diffusion,
Constant Nonaqueous Diffusion, Constant coefficient,
Zero Nonaqueous Diffusion ,
hydrate guest-molecule exchange rate constant , Unit(s), hydrate formation rate constant , Unit(s), hydrate dissociation rate constant,Unit(s), hydrate formation/dissociation rate saturation exponent,
Number of Interfacial Averaging Variables,
Repeat for the Number of Interfacial Averaging Variables
Surface Variable Option,Interfacial Averaging Scheme,
Specifying Interfacial Averaging Schemes
Field variables, which include physical, thermodynamic, and hydrologic properties, are defined in the finite-difference formulation at the node centers. Conversely, flux variables are defined at node interfaces. Computation of flux variables requires knowledge of field variables at node interfaces. Values of flux variables at node interfaces are evaluated by averaging the field values for the two nodes adjoining an interfacial surface. Interfacial averaging schemes may be declared individually for each field variable through the Interfacial Averaging Variables input.