`carb`¶

Macro carb is used to set up a \(CO_2\) problem. Input following the problem type is grouped using sub keywords.

Group 1 - IPRTYPE

Group 1 - KEYWORD

KEYWORD co2pres

JA, JB, JC, PHICO2, TCO2, ICES

KEYWORD co2flow

JA, JB, JC, SKTMP, ESKTMP, AIPED, IFLG_FLOWMAC

KEYWORD co2diff

JA, JB, JC, DIFF, TORTCO2

KEYWORD co2frac

JA, JB, JC, FW, FL, YC, CSALT, INICO2FLG

KEYWORD userprop

DENC, DENCP, DENCT, ENC, ENCP, ENCT, VISC, VISCP, VISCT
DENW, DENWP, DENWT, ENW, ENWP, ENWT, VISW, VISWP, VISWT

KEYWORD brine

Input is terminated with KEYWORD end carb or endcarb.

Input Variable	Format	Default	Description
IPRTYPE	integer		1 = Water only problem (2 DOFs) 2 = \(CO_2\) only problem (2 DOFs) 3 = \(CO_2\)-water problem, no solubility (3 DOFs) 4 = \(CO_2\)-water problem, with solubility (4 DOFs) 5 = \(CO_2\)-water-air with solubility (5 DOFs)
KEYWORD	character		Remaining input is grouped using sub-macro keywords.
KEYWORD “end carb” or “endcarb”	End of carb input.
KEYWORD “co2pres”	Set up the initial pressure (uses the same format as the pres macro)
PHICO2	real		Initial \(CO_2\) pressure (MPa).
TCO2	real		Initial \(CO_2\) temperature (oC)
ICES	integer	0	Initial guess for phase state of \(CO_2\) (actual phase will be calculated internally), ICES settings are: 1 = liquid 2 = two-phase liquid and vapor 3 = vapor 4 = super-critical \(CO_2\).
KEYWORD “co2flow”	Set up co2 flow boundary conditions (similar to the flow macro used to set up water boundary conditions)
SKTMP	real		For IFLG_FLOWMAC = 1, 2, 3, 4, 5 or 9 \(CO_2\) flowing pressure (MPa). For SKTMP = 0 the initial value of pressure will be used for the flowing pressure. For IFLG_FLOWMAC = 6 or 7 water mass flow rate (kg/s). For IFLG_FLOWMAC = 8 \(CO_2\) flowing saturation.
ESKTMP	real		For IFLG_FLOWMAC = 1, 2, 3, 6, 7 or 9 Enthalpy of fluid injected (MJ/kg). If the fluid is flowing from the rock mass, then the in-place enthalpy is used. If EFLOW<0, then ABS(EFLOW) is interpreted as a temperature (C) and the enthalpy calculated accordingly. For IFLG_FLOWMAC = 4 or 5 \(CO_2\) flowing saturation. For IFLG_FLOWMAC = 8 mass fraction of CO2
AIPED	real		For IFLG_FLOWMAC = 1, 2, 4 or 9 \(CO_2\) impedance parameter. For IFLG_FLOWMAC = 5 or 6 value is ignored. For IFLG_FLOWMAC = 7 \(CO_2\) mass fraction in water For IFLG_FLOWMAC = 8 Water mass flow rate (kg/s).
IFLG_FLOWMAC	integer	0	Flag specifying boundary condition type, IFLG_FLOWMAC values: 1 = Constant pressure boundary condition with inflow or outflow allowed. AIPED is user specified 2 = Constant pressure boundary condition with only outflow allowed. AIPED is user specified 3 = Constant pressure boundary condition. AIPED is calculated in the code based on block geometric parameters. 4 = Constant pressure and constant saturation boundary condition. AIPED is user specified 5 = Constant pressure and constant saturation boundary condition. AIPED is calculated in the code based on block geometric parameters. 6 = Constant free phase \(CO_2\) mass flow rate boundary condition. 7 = Constant source of water with specified mass fraction of CO2 (kg/s) 8 = ???? 9 = Partial explicit update of nonlinear part of \(CO_2\) constant pressure
KEYWORD “co2diff”	Read \(CO_2\) diffusivity in water
DIFF	real		Diffusion
TORTCO2	real		Tortuosity for \(CO_2\)-water vapor diffusion.
KEYWORD “co2frac”	Read initial \(CO_2\), air, water/brine saturation. FG, CO2/air-rich gas saturation (volume fraction), \(FG = 1 - FW - FL.\)
FW	real		Water-rich liquid saturation (volume fraction).
FL	real		\(CO_2\)-rich super-critical/liquid phase saturation (volume fraction).
YC	real		Mass fraction of \(CO_2\) in the \(CO_2\)-rich phase.
CSALT	real		Initial salt concentration in water for brine (ppm) (only used if “brine” keyword is invoked.)
INICO2FLG	integer	0	Flag to override \(CO_2\) fractions read from restart file. If set to 1 the input values are used instead of those read from the restart file.
KEYWORD “userprop”	Read user defined properties for \(CO_2\) and brine
DENC	real		\(CO_2\) density (\(kg/m^3\))
DENCP	real		Derivative of density with respect to pressure.
DENCT	real		Derivative of density with respect to temperature.
ENC	real		\(CO_2\) enthalpy (\(MJ/kg\)).
ENCP	real		Derivative of enthalpy with respect to pressure.
ENCT	real		Derivative of enthalpy with respect to temperature.
VISC	real		\(CO_2\) viscosity (\(Pa \cdot s\))
VISCP	real		Derivative of viscosity with respect to pressure.
VISCT	real		Derivative of viscosity with respect to temperature.
DENW	real		Brine density (\(kg/m^3\))
DENWP	real		Derivative of density with respect to pressure.
DENWT	real		Derivative of density with respect to temperature.
ENW	real		Brine enthalpy (\(MJ/kg\)).
ENWP	real		Derivative of enthalpy with respect to pressure.
ENWT	real		Derivative of enthalpy with respect to temperature.
VISW	real		Brine viscosity (\(Pa \cdot s\))
VISWP	real		Derivative of viscosity with respect to pressure.
VISWT	real		Derivative of viscosity with respect to temperature.
KEYWORD “brine”	Invoke option for brine in the simulation. (salt-concentration dependent \(CO_2\) solubility)

In the following example, zone 1 is injecting \(CO_2\) dissolved water at 0.001 kg/s. The temperature is 20oC. The water has a dissolved \(CO_2\) mass fraction of 0.3. The code will check internally whether the user specified mass fraction exceeds the equilibrium mass fraction calculated using the pressure and temperature values of the injection node. In case it does exceed that value, it is fixed at the equilibrium mass fraction. The user can specify a value of “zero” and the code will automatically fix the dissolved \(CO_2\) mass fraction at the equilibrium value. Zone 2 is maintained at initial pressure using “aiped” calculated internally.

carb
    4

co2pres
     1     0     0     3.     20.     4
    -1     0     0     13     20.     4
    -2     0     0     .6     20.     4

co2frac
     1   0   0   1.0         0.0       0   100000    0
    -1   0   0    0.9465   .0535       0   0.         0.

co2flow
    -2 0 0   0        -20.   -1.e-1    3
    -1 0 0 -0.0001    -20.     0.      6

end carb

carb¶

`carb`¶