Problem with Non-Isothermal Simulation (ECO2N)

[Ethan]

I have been simulating CO2 injection into a multi-layered radial model under isothermal conditions without any issues. The simulations have been running smoothly and are usually finished in less than an hour for a 2400 cell grid (~1300 time steps for 50 years simulated time). I have attempted to run the same simulations under non-isothermal conditions and things fall apart pretty quickly. What I mean is that the simulation runs for approximately 1 day simulated time (35 time steps) and after several attempts to reduce the time step, it aborts.

The following error is reported in the output file before reducing the time step size: CANNOT FIND PARAMETERS AT ELEMENT * 1*

I have also noticed that the temperature in the injection blocks is an order of magnitude lower than the adjacent blocks, which leads me to believe that the injected fluid enthalpy is incorrect.

All the simulation parameters are the same and I have accounted for the injected CO2 enthalpy and also performed an initialization run prior to beginning injection (i.e. I performed a non-isothermal equilibration simulation for 100 years). The enthalpy numbers for CO2 that I am using were calculated from the NIST Chemistry Webbook, so I believe they are accurate.

Are there any other critical parameters that I am not taking into consideration? Does this problem sound indicative of an imposed injection rate that is too high for the system being modeled?

Any insight would be greatly appreciated.

Thanks,

Ethan

[swenson]

I have been simulating CO2 injection into a multi-layered radial model under isothermal conditions without any issues. The simulations have been running smoothly and are usually finished in less than an hour for a 2400 cell grid (~1300 time steps for 50 years simulated time). I have attempted to run the same simulations under non-isothermal conditions and things fall apart pretty quickly. What I mean is that the simulation runs for approximately 1 day simulated time (35 time steps) and after several attempts to reduce the time step, it aborts.

The following error is reported in the output file before reducing the time step size: CANNOT FIND PARAMETERS AT ELEMENT * 1*

I have also noticed that the temperature in the injection blocks is an order of magnitude lower than the adjacent blocks, which leads me to believe that the injected fluid enthalpy is incorrect.

All the simulation parameters are the same and I have accounted for the injected CO2 enthalpy and also performed an initialization run prior to beginning injection (i.e. I performed a non-isothermal equilibration simulation for 100 years). The enthalpy numbers for CO2 that I am using were calculated from the NIST Chemistry Webbook, so I believe they are accurate.

Are there any other critical parameters that I am not taking into consideration? Does this problem sound indicative of an imposed injection rate that is too high for the system being modeled?

Any insight would be greatly appreciated.

Thanks,

Ethan

Ethan,

The temperature at the injection block is a good clue. One way to verify the enthalpy is to just run a single cell problem at your injection conditions and produce at a small rate from the cell. The production enthalpy will then be printed out.

If you still have questions, please send your PetraSim file to support@thunderheadeng.com and we will take a look.

Thanks,

Dan Swenson

[Ethan]

Ethan,

The temperature at the injection block is a good clue. One way to verify the enthalpy is to just run a single cell problem at your injection conditions and produce at a small rate from the cell. The production enthalpy will then be printed out.

If you still have questions, please send your PetraSim file to support@thunderheadeng.com and we will take a look.

Thanks,

Dan Swenson

Dan,

Thank you very much for the suggestion. I will try it out and see what happens.

Take care,

Ethan

[Alison]

Hi Ethan:

You also might want to take a look at this posting:

http://www.rockware.com/forum/index.php?sh...amp;hl=enthalpy

It has some suggestions from Karsten Pruess on how to deal with enthalpy and temperatures in TOUGH2.

Thanks,

Alison

[Johny5]

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[monkeyking]

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