Localized Corrosion of Steels in Geothermal Steam/Brine Mixtures

Abstract

Coupons of eight different carbon and chrome-moly alloy steels were exposed to high temperature, high salinity wellhead brine blow at a geothermal well in the Salton Sea Geothermal Field for periods of up to six months. The corrosion rate and corrosion attack morphology of each coupon was determined. Exposure time was a test variable and ranged from one month to six months. Test results indicate that carbon steels generally suffer high corrosion rates and are susceptible to several localized attch which shows a mesa canyon pattern,. Chrome-moly alloy steels corrode at much lower rates and show an attack pattern of small shallow pits. With time, these its grow mostly in the lateral direction. These results suggest that chrome-moly alloy steels offer significant improvement over carbon steels and that the disk shaped pits are not likely to lead to rapid perforation.