Estimation of Heat Discharge Rate at the Permeable Surface of a Geothermal Reservoir

Abstract

This paper describes a method for estimating the heat discharge rate at the permeable surface of a geothermal reservoir. This method is based on the so-called, film theory, in which a liquid film is assumed to be a thin layer of water on the ground surface. This assumption yields a new boundary condition, which is applicable to a numerical analysis of mass and heat transfer in the reservoir. Using the numerical solutions, we can estimate the mass and the heat discharge rates and their distributions on the surface in detail. The boundary condition proposed applies to the analysis of already existing observed data on the Takenoyu geothermal area (Kumamoto, Japan), whose special feature is the non-existence of cap rock. The calculatcd values correspond quite well with the observed data on the mass and the heat discharge rates on the surface, their distributions, and the temperature distribution in the reservoir.