GAS Phase with PhreeqcRM

[Christinali91]

Dear David,

I am working on a CO2 sequestration simulation using PhreeqcRM and having a question about updating the gas phase(fugacity). For the transport problem, we can use RM_GetConcentrations and RM_SetConcentrations to update all the components, so I wonder if there is a similar PhreeqcRM function to update the gas phase as well. Right now, I am using 'EQUILIBRIUM_PHASES_MODIFY', 'USER_PUNCH; PUNCH PR_PHI', and RM_RunString to update the gas phase. Is there a better way to do it using PhreeqcRM?

Thanks so much for your help!

Best,
Christina

[dlparkhurst]

There is not a PhreeqcRM method to set gas concentrations or fugacities. To be honest, I am not sure how to do it myself; I have not dealt with multiphase flow. What information about gases do you have after a transport step? Pressure, fugacity, concentration, volume, pr_phi? Does transport account for non-ideal effects?

[Christinali91]

Hi David,

Thanks a lot for your quick reply. I want to know the fugacity of gas after the transport step. After that, I'll compare the fugacity from the Phreeqc side with the fugacity obtained from the equation of state, then iterate between these two until it converges. Yes, the non-ideal effects are considered in the our transport code.

I know in IPhreeqc we can use AccumulateLine() to modify EQUILIBRIUM_PHASES. I guess this is equivalent to RM_RunString in PhreeqcRM, right?

Code example:

Code: [Select]

                   Ierr=AccumulateLine(Id_phreeqc_initialization,"SELECTED_OUTPUT")
                   Ierr=AccumulateLine(Id_phreeqc_initialization,"-RESET FALSE")
                   Ierr=AccumulateLine(Id_phreeqc_initialization,'USER_PUNCH')

                   DO  I=1, NO_HC_GC
                     Ierr=AccumulateLine(Id_phreeqc_initialization,'-Heading   PR_PHI_'// TRIM(ADJUSTL(NAME_HC_GC(I))))
                   END DO

                   DO  I=1, NO_HC_GC
                      CTR_INT=(I)* 10
                      WRITE(CTR_STR,*) CTR_INT
                      Ierr=AccumulateLine(Id_phreeqc_initialization,CTR_STR//'  PUNCH PR_PHI("'// TRIM(ADJUSTL( NAME_HC_GC(I)))//'")')
                   END DO

                     WRITE(DUMMY_STR,*) 1
                   Ierr=AccumulateLine(Id_phreeqc_initialization,'EQUILIBRIUM_PHASES'//DUMMY_STR)

Thanks again for your help!

Best,
Christina

[dlparkhurst]

I need to know if you are running in parallel? and if you are using OpenMP or MPI?

[Christinali91]

Hi David,

Yes, I am running in parallel. We are using OpenMP right now and plan to switch to MPI in the future.

Best,

[dlparkhurst]

I assume you are using EQUILIBRIUM_PHASES_MODIFY. You can define a string with a series of EQUILIBRIUM_PHASES_MODIFY, one for each chemistry cell (which may or may not differ from the set of transport cells). You can define the set in pieces or all at once, whichever is easier. I would just string them together without END statements in between.

You would then RM_RunString with the worker flag (first flag) set. The commands will be executed in each thread for OpenMP or each process for MPI. It is not the most efficient approach because the the commands for all cells will be executed by each thread or process, even though only a fraction of the cells are actually defined in each thread or process. Most of the definitions will generate a warning that the EQUILIBRIUM_PHASES definition is not present in the thread or process, but all of the EQUILIBRIUM_PHASES for the cells will be updated regardless of which thread or process they are on.

Are you iterating to determine a source/sink term for the transport equations?

[Christinali91]

Hi David,

Thanks so much for your advice. I'll give it a try. The iteration is not for a source term but phases determination. The transport equation is sequentially coupled with the geochemistry module and EOS module. The last two modules may give different fugacity results. Therefore, we want to iterate between geochemistry and EOS to make sure the fugacity results are consistent.

Thanks again!

Best,
Christina