transport modeling

[elham]

Hello all,
I wrote a program that calcite and CO2 exist in region. Does calcite dissolution occurs when initial solution and injection solution are same? I think that calcite dissolution have not to occur but when I wrote its program my answer is opposite. I attach my program at the bottom.

Many thanks,
Elham

[dlparkhurst]

You defined solution 1-100, and then you reacted those solutions with calcite and SAVEd them. Then you defined solution 0, but it has no carbon and is not reacted with calcite. What should happen when solution 0 reaches cell 1 with equilibrium phases containing calcite?

[elham]

Hello
Thank you for your answer.
I attached one data file that contain USER_GRAPH part. As you can see from the curve, when the injection and initial solution are the same, the calcite dissolution is occurred.
Actually I think that because of the similarity between components and concentrations of both initial and injection solutions, the equilibrium state should reach very soon and almost should not have any calcite dissolution.
Based on the information in one of the master thesis that I have studied, when the low salinity water is been injected, calcite dissolution is more than when high salinity water is injected. Because the high salinity water is much similar with initial solution than low salinity water.
Also I attached low salinity water data file and I appreciate that you compare both data files.
Sincerely
Elham

[dlparkhurst]

This input will generate a column and infilling solution such that no reactions will occur as the infilling water penetrates the column.

Are you sure you want CO2 in all of the cells?


SOLUTION 1 Initial solution
    temp 85
   pH 5.7
   units mol/kgw
   pe 12 O2(g) -0.68
   Na   0.751
   K    0.0102
   Ca   0.0296
   Mg   0.00551
   Ba   0.000721
   Sr   0.000696
   Cl   0.78
   S    0.000198
   B    0.00658
   Al   0.0000371
  Si   0.000855
  Li   0.001
END

EQUILIBRIUM_PHASES 1-100
calcite   0 0.94
CO2(g)   0.14
END
USE solution 1
USE equilibrium_phases 1
SAVE solution 0-100
END
EXCHANGE 1-100
 X 4.5e-1;  -equilibrate 1
END

[elham]

Hello
Thank you for your useful guidance.
As you asked me I want CO2 in all of the cells.
I ran your program, as you said calcite dissolution did not occur, now I have two questions about the program. Firstly, do not matter that you omit the transport term because I need inject water to the column. Secondly, if I want to inject one fluid that is different to initial water, for example high salinity water or low salinity water, then I see their effect on calcite dissolution. I appreciate that you say how can I write the program?
As you can see from below, I attached two data files which is about high and low salinity water injection. By running them unfortunately I reached to opposite result that showed low salinity water dissolved calcite later than high salinity water. This result is completely in contrast with my point of view. Because on my studies low salinity must dissolves calcite in much less pore volumes water than high salinity water.
Sincerely
Elham

[dlparkhurst]

I omitted the TRANSPORT block for simplicity and to emphasize the effects of reaction and SAVE.

I think you have your calculations running, so it is up to you to understand the geochemistry.

[elham]

thank you very much.
I hope, I can solve my problem by more effective studies.

[dlparkhurst]

Consider that neither solution has any carbon definitions, so both will be undersaturated with calcite, and that the high salinity water has calcium defined, which will affect the amount of calcite that will dissolve.