大岳生産井の蒸気・熱水噴出量の経年変動と還元の影響

抄録

It is seen from an observation of steam and hot water flow rates for a long period of 7 to 10 years that there are three kinds of decline, namely (1) steam flow rate shows a decline of 3 stages for 0-7 production well, a fixed rate for 0-8 and 0-9, and a periodical decrease for 0-10 and the total of 4 production wells at Otake, and (2) hot water rate gives a linear decrease of two stages, a periodical increase for 0-9 and 0-10, and a periodical change for 0-8 and the total of 4 production wells. Of course, the mutual interference exists between 0-8 and 0-10.
After the reinjection, (1') steam flow rate shows an unchange for 0-8, a little increase for 0-7 and 0-9, and an increase for 0-10 and the total, and (2') hot water flow rate gives such various declines as a fixed state for 0-8, an increase for 0-7 and 0-9, a periodical decrease for 0-10, and a periodical increase for the total.
Dryness fluctuations and the inclination of the enthalpy of a steam-water mixture before reinjection show a gradual increase for 0-7, a decrease in step for 0-8, a slight increase for 0-9, an irregular decrease for 0-10, and a periodical decrease for the total. After the reinjection, they show a decrease for 0-7, a definite increase for 0-8, a little increase for 0-9, an increase and decrease for 0-10, and a periodical change for the total.
Heat discharge from wells indicates two kinds of tendency, that is, one is in unchanged state by the reinjection, which applies to 0-8 and 0-10, and the other is in increased state for 0-7, 0-9 and the total.
The effect of reinjection to the production wells is that the steam rate from 0-7 is affected by R2, and hot water flow rate, dryness, enthalpy and heat discharge from the same well are subiect to the influence of the reiniections, Rl and R2. In 0-9, steam flow rate and heat discharge show an increased state under the influence of reinjections, R1 and R2, which produce an effect upon hot water flow rate graph. In 0-10, steam and hot water rates, dryness and enthalpy are influenced by the reinjection, R2. The influence of reinjection, R1 and R2 occurs on the curves of steam and hot water flow rates, dryness, enthalpy and heat discharge for the total of 4 production wells. Particularly, no influence of reinjection is obtained for 0-8 production well.
Finally, the production capacity of geothermal energy for 4 wells is written as 0-9, 0-10, 0-8, and 0-7 in descending order.