A Simple Engineering Analysis Method to Evaluate the Geothermal Potential from a Hot Water Aquifer

Abstract

Axisymmetric analytical solutions for transient heat transport in geological media are generally derived using Lauwerier’s model. In this study, an axisymmetric solution for a water injection well based on Lauwerier’s model was derived with constant well temperature conditions. Using the convective heat transfer boundary condition, the model considers both the conduction in the aquifer and the heat exchange at the boundary. This solution intuitively illustrates the temperature distribution within the aquifer and therefore allows us to develop a simple engineering method that can determine a suitable location for an extraction well. It can also evaluate the amount of geothermal energy that can be extracted given different positions of the extraction well in relation to the injection well. In order to utilize the analytical solution, one of the input parameters is the heat transfer coefficient at the convective heat transfer boundary condition. In this study, a series of finite element analysis was conducted to determine an equivalent heat transfer coefficient from a given geometry, groundwater extraction rate and thermal properties of the geothermal aquifer and aquitard. Using the analytical solution coupled with the numerical results, it is possible to conduct a simple and fast estimation of geothermal potential of a particular site.