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Abdulaziz

Carbonate acidizing -(Matching ICP result ) - Help to setup initial rock sample and fluid constrains on the system

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Greetings all,

I conducted  HCl ( acid ) core flooding experiments at room temperature on cylindrical limestone rock samples (2.5 cm in diameter 5 cm long) which are mainly composed of ( ~ 97 % calcite from XRD analysis ) and the produced water (effluent) was chemically analyzed for cations using Inductively Coupled Plasma (ICP) spectroscopy to assess the dissolution reaction phenomena.

the chemical equation is as follows : CaCO3 + 2HCl ---> CaCl2 + CO2 + H2O                                                        

My aim is to get the dissolution reaction rate constant and the diffusion coefficient for the conducted experiment by matching laboratory ICP result (Ca++)  with the model (X1t).

I have read transport reactive and other documentation but I am missing something. 

I used X1t app to simulate the acidized core flooding experiments and match the laboratory ICP result.

my concerns are the followings : 

How precisely can I put the constraints on the initial system for the rock sample and the injected acid solution? I am a little bit confused about the input units ( mg/kg, free kg, mmol/kg, ..etc). I am only aware of the limestone rock sample weight ( 50 g) , porosity (22%) and the concentration of the injected acid (pH, wt% ).  how would I put the value of the followings with their units:

  • H2O .... free kg
  • H+ ..... 4 (pH) .. for example !
  • Cl- ...  
  • Ca++ ( mineral ) ...
  • HCO3- ....
  • do I need to equilibrate the fluid and the rock in the initial pane in constraints on the initial system, and if so, how would I equilibrate them?
  • injection rate was 10 cm3/min. how would I mimic the laboratory injection rate within the X1t  the discharge ( injection rate) unit (cm/s, cm3/cm2/s, ..etc)?
  • The laboratory domain was a cylindrical core sample (2.5 cm in diameter 5 cm long) , how would I simulate that domain in the model, I used a spherical domain with r1: 1.25 cm, r2: 1.26 cm and nodes (Nx) = 5, please advise the appropriate way.

 

Your support in this matter is highly appreciated.

 

regards

Abdulaziz

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Hi Abdulaziz,

The main purpose of The Geochemist’s Workbench® software package is geochemical reaction modeling and reactive transport modeling using parameters like rate constants and diffusion constants. You may estimate their optimum values by trial and error, though. For example, the Microbial Populations lesson on the GWB Online Academy describes how to adjust the rate constant to visually match experimental data. 

You can set most basis entries as bulk or free constraints. For a bulk constraint, the value you set refers to the entire thermodynamic component, whereas for a free constraint, it refers to the particular species only. The Ca++ component, for example, might include the Ca++ species, as well as Ca(OH)2(aq), CaHCO3(aq), etc. If you set 10 “mg/kg” Ca++, the concentration is for the sum of those species. If you set 10 “free mg/kg” Ca++, though, the concentration refers only to the individual Ca++ species.

If you are looking at the reaction between the fluid, and the rock, as the fluid traverse through it, you don't probably need to equilibrate the fluid and rock. For more information, please read section 3.10 in the GWB Reaction Modeling Guide.

In a spherical domain, the length of the domain is r2-r1. Please read section 3.1 in the GWB Reactive Transport Modeling Guide.

In future, please don't post your question in different topics. If you need further help, please attach your script.

Thanks,

Melika Sharifi

Aqueous Solutions LLC

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Hi Melika,

Thanks for your reply. when I  submitted my case in the forum, an error message appeared and I ended up submitting the question 4 times without knowing it was posted at the first attempt. sorry about that.

I used X1t app to simulate the acidized core flooding experiments and match the laboratory ICP result.

the chemical equation is as follows : CaCO3 + 2HCl ---> CaCl2 + CO2 + H2O   

my concerns are the followings : 

How precisely can I put the constraints on the initial system for the rock sample and the injected acid solution? I am a little bit confused about the input units ( mg/kg, free kg, mmol/kg, ..etc). 

I am only aware of the limestone rock sample weight ( 50 g) , porosity (22%) and the concentration of the injected acid (pH, wt% ).  how would I put the value of the followings with their units:

  • H2O .... free kg 
  • H+ ..... 4 (pH) .. for example !
  • Cl- ...  
  • Ca++ ( mineral or ... ) ...
  • HCO3- ....
  • do I need to equilibrate the fluid and the rock in the initial pane in constraints on the initial system, and if so, how would I equilibrate them?
  • injection rate was 10 cm3/min. how would I mimic the laboratory injection rate within the X1t  the discharge ( injection rate) unit (cm/s, cm3/cm2/s, ..etc)?
  • The laboratory domain was a cylindrical core sample (2.5 cm in diameter  5 cm long) , how would I simulate that domain in the model, I used a spherical domain with r1: 1.25 cm, r2: 1.26 cm and nodes (Nx) = 5, please advise the appropriate way.

 

I have attached 2 different files. please advise which one of them i should be simulating my lab work with. 

Carbonate acdizing.x1t

Aziz HCl.x1t

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