Discussion Forum

Hi everyone,

I am simulating a multi-stage hydraulic fracture completion in a geothermal reservoir. The idea of the model is quite simple: inject cold fluid into a well (which is connected to a fracture) and allow the fluid to travel along the fracture to extract heat from the surrounding rock and collect the heated fluid at another well.

Here is the issue, mass and energy transfer between the rock and the fracture does not seem to hold. If you look at the temperature of the fracture it is the same temperature of the injection fluid throughout (which means heat conduction from the rock is not being applied to the fracture). I even have defined the weak form source terms for mass and energy flux at the interface, but no luck there. The rock is a 3D block and the fracture is a 2D surface embedded inside the block. Not sure if continuity is automatically applied on the fracture surface since the geometry is completed with a union.

If I explicitly model the fracture (e.g., circular shape that is ~2 mm), then I get the results i expect, but meshing is quite difficult and computation time is very large. I assume this means that an embedded surface inside a 3D domain does not have continuity?

Any suggestions would be helpful.