Study of Fumarole : Part I Vertical Temperature Distribution in Steam Wells

Abstract

Vapour temperature in the steam well bored in thermal area rises generally with the depth, but the temperature gradient is various. This refers to the difference of flow rate, temperature of vapour and geothermal condition of surrounding rock. If the ground temperature around the well is nearly to the vapour temperature in the well, the vapour is not cooled by thermal conduction but only by adiabatic change. While, if the ground temperature is lower than that of the vapour, cooling by the surrounding rock may be chief factor for the vertical temperature distribution. As an example of the former, we give Geyser Well-4, discussing the temperature distribution with the adiabatic equation. Beppu-Hakuryu Well is cited as an example of the latter in which the temperatures at each depth are calculated by an approximate solution taking both coolings into account. The results were compared with observed values. Kuzyu-Otake Well-3 was bored to 900m in 1956, but at present, it is clogged by the scale at 65m below the ground surface and the mass of issuing gas is little. The vapour temperature is 98.4℃ at 65m depth, 97.2℃ at the upper end of the well. This little difference of the temperature is due to the condensation of the vapour, that is, the heat taken by the cooling may be compensated by the condensation.