Natural CO2-Rich Steam-Heated Waters in the Broadlands-Ohaaki Geothermal System, New Zealand: Their Chemistry, Distribution and Corrosive Nature
- Key words
- New Zealand
- Location
- Broadlands, New Zealand; Ohaaki, New Zealand; Taupo Volcanic Zone
- Conference
- Geothermal Resources Council Transactions
- Year
- 1985
- Session
- Corrosion; Carbon dioxide; Brine chemistry; Isotopes
- Language
- English
Abstract
Severe external corrosion of 12 to 16 year old well casing has been noted at 300 to 600 m depth in the Broadlands-Ohaaki geothermal system. The corrosive fluid is a CO2 rich steam heated water. Chemical and isotope patterns of subsurface fluids indicate that this low chloride steam heated water is widespread but probably discontinuous over the top and on the margins of the deep production fluid. Some degree of corrosion has been noted in all of the seven wells so far examined in detail. Given the extent of the steam heated fluid, more of the 44 wells at Broadlands will probably have corrosion problems. This corrosive CO2 rich water exists in several other New Zealand systems, and may occur at shallow levels in any relatively gassy system, with external corrosion of existing wells yet to be discovered.
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