Effect of heat loss in a geothermal reservoir

This paper reports a three-dimensional (3D) numerical study to determine the effect of heat loss on the transient heat transport and temperature distribution in a geothermal reservoir. The operation of a geothermal power plant, which is essentially an injection-production process, involves reinjection of heat-depleted water after extraction of heat for power production which results in gradual cooling of the reservoir. This study aims at determining the influence of the heat loss from the geothermal reservoir to the surrounding rock media on the temperature distribution due to injection-production operations. Results show that the advancement of the cold-water thermal-front becomes slower due to heat loss which helps in delaying thermal-breakthrough at the production well. The permeability and the thermal conductivity of the confining rocks are found to be crucial parameters influencing the heat loss phenomenon and thus the thermal-front movement in the reservoir. In light of the importance of heat loss, a new strategy of reinjection is discussed here. Injection of cold water in a zone capped by rocks with significant permeability at a finite distance away from production zone is proven here to be a good strategy to avoid premature thermal-breakthrough while maintaining pressure balance.