Hi Tom,
Thanks for such a prompt response!
1. I spent some time reading over the Kinetic Reactions section in the modeling guide today. I did notice the mention of the step size which corresponds to the "delxi" variable. I tried increasing this value by small incriments as well as by orders of magnitude to see if I could get the "Xi step size too small" error to disappear but my efforts were unsuccessful. Am I missing something?
2. I'm assuming by "initial speciation model" you mean the original values I used in SpecE8? If so, those values are the formation water data and converge fine in SpecE8. When I do a batch run with the water and minerals in REACT the system converges successfully as long as there are no clays present (if there are clays the system error reads: Didn't wake up, abandoning path). I tried your suggestion of titrating the minerals in one at a time but found none of them to allow the system to run.
3. I fixed my rate constants because, as you mentioned, they were negative and I realized I had log k rate constants. I converted them to the appropriate values which all turned out to be around +0.99. Despite this change, the system still showed the "Xi step size too small" error. With this change to non log values am I accounting for the (1-Q/K) portion of the rate constant equation that you refered to?
4. Additionally, I have heard from another GWB user that starting with a water/rock ratio of 1 can sometimes help, so I recalculated my rock masses to reflect this W/R=1. Even if I can get these kinetic reactions to converge and be successfull will me lowering the W/R ratio back down to more realistic reservoir ratios affect the reactions again?
I have attached my edited script with the new rate constants.
Reynolds8_Avg_KineticMins3.rea