Analytical and Numerical Solutions of Radially Symmetric Aquifer Thermal Energy Storage Problems

Abstract. The paper discusses analytical and numerical radial solutions of the differential equations for heat transport in water-saturated porous media. In particular, a similarity solution is obtained for a 2D-horizontal confined aquifer with constant radial flow. Numerical solutions are derived using a high-resolution Lagrangian approach suppressing spurious oscillations and artificial dispersion. There is a good correspondence between numerical and analytical solutions.

The primary purpose of the investigation has been to calculate the recovery factor of an Aquifer Thermal Energy Storage (ATES) system with a cyclic repetition of injection and pumping. Solutions covering both instantaneous and delayed heat transfer between fluid and solid, as well as time varying water flow, are derived and applied to a one-well test case.

In hydrological terms, these solutions are relevant for a wide range of problems where groundwater reservoirs are utilized for extraction and storage (viz. irrigation; water supply; geothermal extraction).