Help with model of open boreholes

Hot water is injected into a row of boreholes 6 m apart and 20 m deep and is extracted from another identical row of boreholes 6 m away. I would like to model the temperature of the extracted water for a given injection temperature and rate. Porous media, no groundwater flow, no BHE U-tubes. Any advice on how to proceed, building on existing models or benchmarks, would be greatly appreciated!

The ogs process that fits your problem best would be HT (hydrothermal). Specifically, nodal source terms for water injection/extraction are required at the borehole ends. In addition, temperature Dirichlet boundary conditions are required at the injection boreholes. Unfortunately, there are no such benchmarks available. But you could refer to other HT benchmarks and nodal source term benchmark for input file specification.