Vivek Patil

Hello, I have an experimental data set of calcite precipitation kinetics. I want to model it in REACT using kinetic equations for two reactions: surface precipitation of CaCO3 and conversion of bicarbonate to CO2(g). I want to optimize the values for various kinetic parameters (different rate constants, surface area etc) in these two reactions, such the combined outcome matches measured values from my dataset. Are there any ways to apply some kind of optimization algorithms within GWB? Or is this something that I'll have to do externally? I am using GWB 9.0. Thanks in advance! Vivek

Hi Brian and others, I have a GWB 9.0 license installed on my windows 8 machine. I am considering upgrading to windows 10. Will this affect the functioning of GWB 9 in anyway? Has anyone tried it on versions prior to GWB 10? Thanks, Vivek

Hello Brian and others, We collected some water composition data of a CO2-saturated spring. I tried to calculate the speciation, mineral saturation and charge imbalance using SpecE8. However, the charge imbalance calculated by SpecE8 is 11.09% while my manual calculations tell me it is 3.55 %. I am not sure why this is happening and if I am going wrong somewhere. I am not allowed to attach excel sheets here but I am attaching the input file of SpecE8. I used GWB 9.0. Thanks in advance for any help. Best, Vivek CGwater.sp8

Thanks a lot Brian! I greatly appreciate your help! Best, Vivek

Hi Brian, Thanks for your replies. I tried and made changes to my models according to your suggestions. Also my group purchased two new licenses for GWB 9.0 so I am now working on it. I realise that GWB 9 can handle more kinetic laws than 8. Some of my models having a lot of kinetic reactions run on 9 while crash on 8. Am I right? Can you tell me the maximum number of kinetic rate laws that gwb 9 can handle for a system similar to one in my previous posts? Also I want to specify different rate constants for precipitation and dissolution of a single mineral. Do I need to put two entries for the same mineral? Or will I need a custom script for that? Thanks for your help! Vivek

Hi Brian, Thanks for a very prompt and helpful reply. I will try as you suggested by putting one kinetic rate law at a time with carbonates going in the last. I have considered a flow through system, however I wanted to do a stagnant system as a preceding step to it. Indeed a flow system might be more realistic. As for O2(aq), I was expecting small amount of Hematite and the model didn't allow me to precipitate Hematite without O2 in the basis. One more issue that I sometimes face in GWB (not in this particular simulation): When I try to pick up the entire system (after a reaction path), the software changes the minerals in the system on its own. For example, in one of my models I tried to react CO2(g) in a stagnant system for 50 yrs. Then I picked the entire system and tried to react a brine using the flush model to mimic a flow-through system. But my original primary minerals were swapped out of the basis and new minerals were replaced. Do you know a way to get around this? Many thanks for great suggestions. Regards, Vivek

Hi Brian and all, I am trying to do this particular simulation to study kinetic water-rock interactions in presence of CO2. Please find my .rea file attached. I used GWB 8.0. In my simulation I first define my initial equilibrium by swapping the rock minerals into the basis. Then I react 50 kg of CO2(g) over 50 years. After 50 yrs the CO2 feed is stopped and reactions are traced till 1000 yrs. I suppress all the minerals except primary minerals and those secondary minerals that I except to form along the reaction path. My simulation completes when I define all the minerals at equilibrium. However, it does not even start when I define kinetics for them. I am not able to figure out why so. Notice that I wanted some minerals that were not in the GWB database. I made a new database by adding 5 minerals to the original database. Please find attached my database here. Please suggest if you think there is a better way to frame this problem. Thanks and looking forward to your suggestions. Vivek Patil thermo_vvp.dat trial.rea

Hello GWBers! I am using GWB 8.0 and this question has been troubling me ever since I started using GWB. How to specify the total pressure on the system, be it in REACT or XT. Sometimes, you want to simulate reaction at certain depth in subsurface where the pressure is greater than atmospheric. Please help. Many thanks! Vivek.

Roserun.reaHello, I want to calculate the equilibrium between a given brine and given initial fugacity of CO2 (simulating dissolution of CO2 in brine). To do that I specified the brine composition in REACT and swapped CO2(g) with HCO3- in the basis. I mentioned the initial fugacity as 100 atm and let it run. The equilibrium fugacity of CO2(g) is about 175 atm. I am using GWB 8.0 version. I am attaching here the REACT input file that I am using. Please help me figuring this out! Many thanks in advance, Vivek.