How to define a reasonable heat source term in a THM model in OGS?

Usability
1

Dear all,

I am testing the effects of the injecting fluid temperature on fault stability with a 2D THM model in OGS. But I am not sure how to give a reasonable heat source term in the prj?

For example, I want to inject cold water into a geothermal reservoir:
cold water temperature: 30℃ (303.15K)
geothermal reservoir temperature: 150℃ (423.15K)
injection rate: 1e-6 kg*m^(-2)*s^(-1)

Could anybody tell me how I can set this heat source term?

Best,
Rui

2

More specifically, I would like to know whether this method shown below to calculate the input value of heat source term is correct in OGS?

how_to_define_heat_source_term
how_to_define_heat_source_term1920×1075 202 KB

3

In other words, how could they define this point heat source Q is equal to 150W？How could they get this 150W? Is there any deriving proof?
https://www.opengeosys.org/docs/benchmarks/thermo-hydro-mechanics/consolidation_pointheatsource/#problem-description

4

Solved. Not ΔT, but T. It is because heat is always together with mass. Q should be like this,

how_to_define_heat_source_term_correct
how_to_define_heat_source_term_correct1433×988 73.4 KB

5

In THM process, after my testings, I found when this Q is equal to 0, the temperature would not change; when Q is larger than 0, the temperature would go up; when Q is smaller than 0, the temperature would go down.

So, in summary, Q=cmT is correct in physical law side, but Q=cmΔT is used to set the temperature source term in my case.

6

Hi Rui_Feng, I encountered a similar issue and am confused about how to set the parameters in the prj file. May I ask how to set the boundary conditions in
the prj? If coupling the mass of water injected with heat, what’s the reference temperature in forfumla Q=cmΔT? Looking forward to your reply, thank you.