Temperatures above initial condition temp using injection and production scenario with EOS1

Hello,

I am modelling the flow of water through heterogeneous  media by using two wells, an injector and producer over a 25 year period. The initial temperature condition is set to 100 degrees C and I am reinjecting with an enthalpy of 3.11E5 J/kg (at 25 kg/s). The goal of these simulations is to ascertain how this heterogeneous media affects the final temperature at the production well and how it deviates from the original 100 degrees C initial condition.

I have noticed that the final temperature at some production cells after the simulation is finished are elevated to a value above the initial condition, 100 degrees C. Sometimes the production cells are as high as ~ 107 degrees C. I don't quite understand why this would be the case if I am simulating a closed system where I am reinjecting at an enthalpy that corresponds to ~ 70 degree C water.

Can anyone speculate why I am getting these elevated temperatures?

Thank you!