Numerical experiment on the evolution of vapor-dominated geothermal system

Author(s): Adrianto, Ryuichi Itoi
Department of Earth Resources Engineering, Faculty of Engineering, Kyushu Unuversity, Fukuoka, Japan
International Journal of Smart Grid and Clean Energy, vol. 9, no. 2, March 2020: pp. 431-442
ISSN: 2315-4462 (Print)
ISSN: 2373-3594 (Online)
Digital Object Identifier: 10.12720/sgce.9.2.431-442

Abstract: The evolution mechanism of vapor-dominated geothermal system has not been well understood. Boundary condition plays an important role in numerical simulation of geothermal reservoirs, especially in natural state simulation. The level of uncertainty at the bottom condition in a geothermal reservoir is very high because it is not provided from the wellbore data. This paper aims to understand an evolution mechanism of the vapor-dominated geothermal system with particular interest on bottom boundary conditions. Numerical experiments with vertical two-dimensional reservoir model of porous type were conducted. Parameters such as bottom heat flux, temperature, and flow rate of deep mass recharge were examined. Additionally, setting up fixed vapor saturation at the bottommost layer was also examined. This study suggests that a proper mass recharge should be set as the bottom boundary condition. The recharge amount, if too large, could reduce the size of two-phase zone in the reservoir. A sufficient heat flux is required and the minimum recharge temperature is 240° C in order to generate a two-phase zone in the reservoir.

Keywords: geothermal, vapor-dominated, evolution, boundary conditions
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