TOUGH+HYDRATES convergence issue in phase change
I want to calculate the depth interval at which gas hydrates forms, given P and T initial conditions, fixed on top.
The idea is to run the model until it reaches the equilibrium, so in the output file I can see at which depth the phase state change appears.
The initial conditions are for water and hydrate. The P and T gradients should allow the appearance of gas, dissolved or free, at some depth.
My problem is that the simulation stops, because of the lack of convergence, when the phase change appears. It looks like the simulation fails when the P and T conditions cross the line of P-T equilibrium (Lw-H-V in this case).
I run a simple 1D model with several hundreds of 1m cells and one type of rock. I have tried several combinations of P and T but with the same result.
Could you please tell me if there is something wrong with this approach?
Thanks.
4 replies
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Could you post the main output file here?
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The model run pretty long simulation time (7.8 million days). The message " >>>>>>>> CONVERGENCE FAILURE on time step # 17085 with Dt = 1.350000E+07 seconds, following two steps that converged on <NumNRIterations> = 1
==> STOP EXECUTION AFTER NEXT TIME STEP"may indicate the steady state has reached. You may go ahead for further simulation with this result as the initial conditon.
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If the steady state is not your expect, may sure you have the correct boundary conditions.