PFLOTRAN Question: ERROR: concentration condition null for CO₂ Dissolution-Convection Simulation

[毎熊康平]

My name is Kohei and I am a new user of PFLOTRAN. I am currently trying to set up a simulation to study CO₂ dissolution-convection (density-driven fingering) following CO₂ injection into a heterogeneous sub-seabed formation. I am using SIMULATION_TYPE SUBSURFACE with coupled MODE MPHASE and MODE GIRT.

However, I am stuck at the initial setup and keep getting the following error when defining the initial conditions: ERROR: concentration condition null in condition: initial

This error seems to occur when I try to couple the FLOW_CONDITION and TRANSPORT_CONDITION in the INITIAL_CONDITION block. I have tried two approaches, which have led me into a loop:

1. When I run the simulation without CONCENTRATION DIRICHLET in the FLOW_CONDITION's TYPE sub-block, I get the concentration condition null error.

2. When I add CONCENTRATION DIRICHLET to the TYPE sub-block, I get a different error: ERROR: No value or dataset specified.

Here are the relevant parts of my input file that are causing the issue:

# --- Flow Condition Template ---
FLOW_CONDITION initial
  TYPE
    LIQUID_PRESSURE HYDROSTATIC
    TEMPERATURE DIRICHLET
    # Should CONCENTRATION DIRICHLET be here or not?...
  /
  DATUM 0.d0 0.d0 0.d0
  LIQUID_PRESSURE 1.d7
  TEMPERATURE 45.d0 C
END

# --- Transport Condition Template ---
TRANSPORT_CONDITION initial
  TYPE DIRICHLET
  CONSTRAINT_LIST
    0.d0 initial
  /
END

# --- Constraint (Chemistry Recipe) ---
CONSTRAINT initial
  CONCENTRATIONS
    H+  7.0 pH
    Na+ 1.d0
    Cl- 1.d0
    HCO3- 1.d-3
  /
END

# --- Assign Initial Condition ---
INITIAL_CONDITION
  FLOW_CONDITION initial
  TRANSPORT_CONDITION initial
  REGION all
END

Could someone please advise on the correct syntax for defining the FLOW_CONDITION, TRANSPORT_CONDITION, and INITIAL_CONDITION to properly set an initial state of a saline aquifer under hydrostatic pressure for a coupled MPHASE/GIRT simulation?

Any help would be greatly appreciated.

Best regards,

Kohei

  

[Hammond, Glenn E]

Kohei,

Peter can correct me if I am wrong, but MPHASE does not consider transport of NaCl within the brine, and it is only coupled to CO2 and H2O on the transport side (i.e., specifying NaCl on the transport side has not feedback on flow). For MPHASE, you can follow the regression tests at:

https://bitbucket.org/pflotran/pflotran/src/master/regression_tests/default/scco2/mphase/mphase_chem.in

I recommend trying SCO2 mode:

https://documentation.pflotran.org/theory_guide/mode_sco2.html

https://documentation.pflotran.org/user_guide/cards/simulation/subsurface_flow_modes/sco2_card.html

With examples at:

https://bitbucket.org/pflotran/pflotran/src/master/regression_tests/co2/

You cannot set a hydrostatic pressure profile using a brine. You must set Dirichlet boundary conditions and run the simulation to a steady state (spin up) for the initial condition.

Glenn

From: pflotra...@googlegroups.com <pflotra...@googlegroups.com> on behalf of 毎熊康平 <sassi15...@gmail.com>
Date: Wednesday, October 15, 2025 at 7:54 AM
To: pflotran-users <pflotra...@googlegroups.com>
Subject: [pflotran-users: 8589] PFLOTRAN Question: ERROR: concentration condition null for CO₂ Dissolution-Convection Simulation

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