A Study of the Natural Convection in the Opened Geothermal Reservoir (V)

Application of the opened thermal convection model to the practical geothermal system

Abstract

An opened thermal convection model is applied to the actual geothermal system of the Isawa hot spring, Yamanashi prefecture. The area is underlain by thick diluvial and alluvial formations, and the discharge rate and the temperature of hot water are respective maxima at the No. 24 well and decrease gradually with distance from it. A cylindrical reservoir model is used to simulate the temperature distribution of the hot spring aquifer of the area. In the simulation a try and error technique is used to decide the most suitable model reservoir, which produces the smallest difference between the calculated and observed values. From the results of simulation, it is estimated that: (1) a circular heat source with radius of 410.5 m and the maximum temperature of 336°C lies at the 1368 m deep, and thermal convective current results from the heating in the hot spring aquifer with the permeability of 10^-3μm², (2) hot water of 0.76 m³/s in total flows out from the discharge area with the radius of 1300 m.