Wells geothermal fluids

Nitta, T., Adachi, M., Takahashi, M., Inoue, K. and Abe, Y. (1991) Heavy metal precipitation from geothermal fluid of 87N-15T production well in the Okuaizu geothermal field, Tohoku District, Japan. Mining Geology, 41, 231-242 (in Japanese). 

For the Hveragerdi 4 well, we follow the same procedure, using the data in Table 23.2 and the calculations already shown. In this case, the model predicts that a number of minerals in the LLNL database are supersaturated near the inflow temperature of 181 °C. Close examination reveals that each of the supersaturated minerals contains either Mg++, Ca++, or Fe++, components that are characteristically depleted in geothermal fluids. The Mg++ concentration in this fluid, for example, is just 2 p,g kg-1. 

Injection underground does not necessarily require injection into the geothermal reservoir from which production is derived, because this process carries with it the risks of potential cooling of the production wells and possible adverse impacts on the geochemical characteristics of geothermal fluids. The waste fluid may also be injected into an aquifer other than the geothermal reservoir simply to avoid... 

Geothermal fluids are a common agency for zeolite formation and this has been well documented in Iceland, at Wairakei (New Zealand), and in Yellowstone Park (USA). Often, well-defined zones (illustrated for Iceland in Figure 14)... 

Brine is a geothermal solution containing appreciable concentrations of sodium chloride or other salts. The chemical composition including the salinity of geothermal fluids varies greatly from one reservoir to another. Variations in chemistry and salinity affect the design, maintenance, and longevity of wells and surface equipments. Recent advances in this area include ... 

Table 11. Helium isotopes and concentrations in groundwaters, geothermal fluids, hydrocarbon and carbon dioxide wells. 

William C., Lyons BG, Reuben L. et al. Air and gas drilling manual Applications for oil and gas recovery wells and geothermal fluids recovery wells. 3rd Ed. Gulf Professional Publishing 2009. 

The flashed steam method is less efficient and its requirements for steam properties—cleanliness, high temperature, and high pressure— are usually unavailable in most geothermal fields. The situation is different with the binary cycle system, which is quite efficient and widely used. This wet system involves the transfer of heat from the hot well stream into a more manageable boiling fluid to generate power through a turboexpander. 

In the primary binary loop, production wells recover 170°C hot water from the geothermal reservoir and deliver 3,036 m /lir at 14 bar to heat exchangers in the power plant. Water leaves the heat exchangers at 70-90°C and is recycled to the ground through a re-injection well at a depth of 400-600 m. In the secondary binary loop, the heat from the hot water evaporates the isobutane working fluid at 36 bar and 150°C (Table 4-2). 

The Okuaizu geothermal system is characterized by high temperatures (maximum 340°C), high salinity (about 2 wt% total dissolved solids (TDS)) and large amounts of non-condensable gases (1 wt% CO2 and 200 ppm H2S). The pH of the hydrothermal solution measured at 25°C is 6.44 (Table 2.6). However, the pH of the original fluid in the reservoir is computed to be 4.05. This pH as well as alkali and alkali earth element concentrations are plotted near the equilibrium curve of albite, K-mica, anhydrite and calcite (Fig. 2.19) (Seki, 1991). 

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