| Abstract |
Literature on external casing corrosion (ECC) in oil, gas and geothermal fields is reviewed. ECC in geothermal systems can be related to CO2-rich or acid-sulphate waters. Several cases of ECC due to CO2-rich fluid have been reported in geothermal fields within the Taupo Volcanic Zone (TVZ), including: Brodlands-Ohaaki, Rotokawa, Tauhara and Mokai. The main factors controlling the rate of ECC due to CO2-rich fluid are the CO2 content and the shallow horizontal permeability of the field. It is anticipated that in-field reinjection of mixed brine and condensates may aggravate casing corrosion by pushing CO2-rich fluid towards casings. Solutions are given for the prevention and mitigating of ECC. |