TH simulation in equilibrium

[saturngreen67]

Hi everyone,

I started learning OpenGeoSys a few days ago…Previously I was using another software but since I couldn’t make a BHE inside my model I changed to OpenGeoSys. I have little time left for my master thesis, and I need help with the equilibrium state for thermal boundary condition for the temperature of the earth and pore pressure caused by gravity. Can anyone help me in that regard what I should use and how?

Best regards,

[chleh]

Hi,

I assume you want to know how to apply an inhomogeneous initial pressure and temperature field.
If you have analytical expressions for them, the easiest might be to use a Function parameter. The linked documentation page is not very verbose, but it contains links to many example prj files.

How to create very simple meshes is described here. Boundaries of more complicated meshes the tool identifySubdomains can be used.

For BHEs the following might be helpful, too:

• Heat Transport BHE
• Creating OpenGeoSys Mesh with Inclined Borehole Heat Exchangers
• Creating Mesh with integrated Borehole Heat Exchangers

Best regards,
Christoph

[saturngreen67]

Dear Christoph,

Thanks for getting back to me. For the first part, I just need to model 3 layers of earth (each one is homogeneous) in which heat flux from the bottom boundary is applied. At the same time, gravity causes the pore pressure to equilibrium based on the density of the layers and depth (both temperature and pressure start with an average value for the whole cube). Do you have any recommendations for these parts?

Best regards,
Farid

[chleh]

Hi Farid,

sorry for the late response. Your questions seem very general to me. Do you need advice for modelling things in general? Or for setting up a model in OGS?

In any case, I’m afraid I don’t have the time (and knowledge) to give a tutorial of BHE modelling with OGS. Maybe somebody else from the OGS community has.

If you have a basic running OGS model that you want to base your work on and have specific questions for next steps, I’m sure they will be answered on the forum.

We have some documentation on the website including some tutorials. So, I’m afraid you’ll have to go through the documentation and some test examples to learn OGS.

Good luck.

Best regards,
Christoph

[lurpi]

@saturngreen67

gravity causes the pore pressure to equilibrium based on the density of the layers and depth (both temperature and pressure start with an average value for the whole cube).

To specifiy initial conditions for your model, have a look at this answer and at the python scripts there included:

Import heterogeneous initial stress from an external file

Just for repetition, the initial state will be included in the prj-file by lines like 251 <parameter> 252 <name>initial_p</name> 253 <type>MeshNode</type> 254 <field_name>pressure</field_name> 255 <mesh>results_equilibrium_ts_10_t_315360000000.000000</mesh> 256 </parameter> ... 311 <initial_condition>initial_p</initial_condition> for details about stress I would refer to the code documentation (search in the examples o…

Temperature and pressure are scalar fields, so you will be able to repeat teh same procedure mentioned for both fields.

In general, your problem is complicated by the density dependence on both temperature and pressure.
To obtain your initial conditions, you should be able to apply the same conceptual procedure you would have used with the other software.

If you cannot, in the worst case, you compute the temperature and pressure field with the other software, then import them into your OGS model as initial conditions (using the approach posted above)…

[saturngreen67]

Hi,

Thank you for your reply I did the TH simulation 2 weeks ago. Things worked almost properly so far.

Best regards,
Farid