The article discusses how to estimate the lifespan of a geothermal reservoir in porous rock with fractures. The researchers developed equations to calculate average temperatures in the reservoir and found that cool reinjected fluid in fractures can reach production wells before all the warm fluid is extracted, shortening the reservoir's lifespan. They focused on the impact of fracture parameters like aperture, permeability, and spacing on reservoir depletion. The study suggests that large fault systems in the Salton Sea Geothermal Field could reduce the lifespan of wells if they connect injection and production wells.