Problem initializing a low permeability EOS7C simulation

Hello,

I am trying to set up a model with EOS7C, with which I plan to simulate methane generation within a large, low permeability domain over a long period of time. I am trying to use a method that I was taught in in the past, that is, to run two simulations; an "initialization" run to attain a hydrostatic water pressure profile, and then a second simulation that uses the output from the initialization as an initial condition and simulates introduction of gas into the system.

The initialization simulation only ran successfully when the system had a high permeability (the simulation ran to completion, and a reasonable pressure profile was created, in this case). When I changed the permeability to the very low value that I want to use, the code didn't handle it well. The initialization stopped itself before the intended end time because it was converging too quickly (on the first iteration for 10 consecutive time steps). Also, the pressure profile did not become hydrostatic (in fact, it remained constant everywhere throughout the domain).

The two attached input/output pairs are from these two different initialization simulation attempts, the only difference between which was the permeability. The files called "init01.txt" and "out01.txt" are from the high permeability case, while the files called "init02.txt" and "out02.txt" are from the low permeability case.

Could someone please help me figure out how to get TOUGH2-EOS7C to handle low permeability systems?

Thank you very much,

Mike