♨️ Geothermal Doublet: Fracture Cooling, Thermal Drawdown and Lifetime (2D)

Cross-section of a geothermal doublet: cold water goes down one well, crosses a hot fracture and comes up another well to a power plant. Set depth, gradient, injection temperature, flow rate, well spacing, fracture height and the number of parallel fractures, and watch the cold front creep through the rock, the produced temperature fall over thirty years and the thermal and electric power with them. A finite-difference rock model is checked against the closed-form solution, with four in-page numerical checks.