Heat Beneath Our Feet
The Earth's interior is an immense thermal engine, driven by radioactive decay and primordial heat from planetary formation. At the surface, temperatures are mild — but descend just a few kilometers and rock temperatures reach hundreds of degrees Celsius. Geothermal reservoir modeling predicts these subsurface temperatures to identify locations where heat can be economically extracted. This simulator lets you explore how depth, geothermal gradient, and rock properties determine reservoir thermal state.
The Geothermal Gradient
Temperature increases with depth at the geothermal gradient — typically 25-30°C per kilometer in continental crust, but reaching 80°C/km or more near active volcanic centers. The gradient is governed by the balance between heat flux from below (mantle convection and crustal radioactivity) and thermal conductivity of the overlying rock. Low conductivity sedimentary basins can act as insulating blankets, elevating temperatures at moderate depth.
Heat Extraction and Flow
Converting subsurface heat to useful energy requires circulating fluid through the reservoir. The thermal power extracted depends on flow rate, fluid heat capacity, and the temperature difference between production and reinjection. Higher flow rates extract more power but cool the reservoir faster, creating a tradeoff between short-term output and long-term sustainability that reservoir engineers must carefully optimize.
Reservoir Longevity
Sustainable geothermal operation requires that heat extraction not outpace natural thermal recharge. Reservoir depletion models track the advancing cold front around injection wells and predict temperature decline over decades. Proper well spacing, flow management, and reinjection strategies can sustain production for 30-50 years. Some fields, like Larderello in Italy, have operated for over a century with adaptive management.