Geothermal well

Gases from geothermal wells are collected in the same fashion as fumarole discharges. At geothermal wells, however, it is necessary to use a steam separator in order to efficiently sample the non-condensable gases, which partition into the steam phase. The collected sample then consists of steam plus gas. 

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It is claimed that the cured materials may be used continuously in air up to 300°C and in oxygen-free environments to 400°C. The materials are of interest as heat- and corrosion-resistant coatings, for example in geothermal wells, high-temperature sodium and lithium batteries and high-temperature polymer- and metal-processing equipment. 

Located in Sonoma and Lake Counties in Calif., the geysers complex produces over 900,000 kW of electricity using steam from geothermal wells 7,000 to 10,000 feet below the surface. (U.S. Department of Energy)... 

From the corrosion point of view, it is very important to control the deposition of scale. Removal of deposited scale by mechanical means is the first step. Standard, industrial water-treating techniques can be used to control scale deposition in general. In deep, hot wells or geothermal wells it is best to avoid untreated makeup water (i.e., geothermal brines). 

Fig. 2.11. The temperature dependence of cation/proton activity ratios of geothermal well discharges in Japan. The lines in the figure are recalculated temperature dependences of cation/proton ratios in Icelandic geothermal waters. The dashed curve in B represents the reaction 1.5 K-feldspar + H+ = 0.5 K-mica + 3 quartz (or chalcedony) + K+ (Chiba, 1991). Open circle Takigami, open triangle Kakkonda, open square Okuaizu, solid circle Kirishima, solid triangle Sumikawa, solid square Nigoiikawa.

Analytical results and discharge data of geothermal wells (Seki, 1991)... 

The relation reproduces very satisfactory /hjS observed for Icelandic, New Zealand, Philippine and other geothermal well discharges (Amorsson, 1985). 

L. E. Kukacka and T. Sugama. Lightweight C02-resistant cements for geothermal well completions. Brookhaven Nat Lab Rep BNL-60326, Brookhaven National Lab, 1994. 

R. J. Mouche and E. B. Smyk. Noncorrosive scale inhibitor additive in geothermal wells. Patent US 5403493, 1995. 

Table 23.2. Chemical compositions of water and steam discharged from wet-steam geothermal wells in Iceland (Arnorsson et al., 1983)...

Fig. 23.8. Calculated saturation indices (log Q/K) of various minerals for the Reyk-janes 8 wet-steam geothermal well. The well produces from seven intervals at temperatures varying from 274 °C to 292 °C. The calculated saturation indices suggest an equilibrium temperature between about 285 °C and slightly above 300 °C.

More commonly than it puts out dry steam, a geothermal well puts out a mixture of steam and water above 130°C, or just hot water. A separator is needed in a hot water steam mixture geothermal power plant to separate the flashing steam from the hot water, as shown in Figure 2.23. An additional throttling valve is required to generate saturated steam in a hot-water geothermal power plant. 

Table 4. Gas concentrations in steam from selected geothermal wells ... 

The observed formation of calcite scales in geothermal wells is consistent with calcite saturation calculations (see Fig. 14). The intensity of calcite deposition is largely determined by two factors, the temperature of the water and its salt content (Arnorsson 1978a). In relation to temperature, calcite scale formation is most troublesome around 200 C and it decreases at both higher and lower T. The cause is the temperature variation in the solubility of C02. It is at a... 

Argueta, G. G. M. 1995. Rehabilitation of Geothermal Wells With Scaling Problems. United Nations University Geothermal Training Programme Report, 1995, 207-240. 

Evanoff, J., Yeager, V. Spielman, P. 1995. Stimulation and damage removal of calcium carbonate scaling in geothermal wells A case study. In Proceedings World Geothermal Congress, Florence, 18-31 May, 2481-2486. 

Klein, C. W. 1995. Management of fluid injection in geothermal wells to avoid silica scaling at low levels of silica oversaturation. In Proceedings World Geothermal Congress, Florence, Italy, 18-31 May, 2451-2456. 

Genter, A. Traineau, H. 1996. Analysis of macroscopic fractures in granite in the HDR geothermal well EPS-1, Soultz-sous-Forets, France. Journal of Volcanology and Geothermal Research, 72, 121-141. 

The simplest of the geothermal cycles is the direct-intake non-condensing type. Steam from the geothermal well is directly passed through a turbine and exhausted to the atmosphere without condensation. Such cycles require 15-20 kg steam per generated kWh. Condensing plants (with condensers at the turbine outlet) need only... 

If the geothermal well produces relatively low-temperature fluid (<175 °C), electricity can also be generated by means of binary cycle plants, albeit with low efficiency (see below). The binary system utilizes a secondary working... 

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