Field Testing of Geogard 8822 Corrosion Inhibitor in Acid-Treated Geothermal Brine

Abstract

The use of high temperature Geogard 8822 corrosion inhibitor in brine treated with sulfuric acid was evaluated in an experiment at Nasuji Sector, Southern Negros Geothermal Production Field, Philippines. Brine from a separator vessel was acid treated to reduced the pH from ~7 to about 4–4.5 and was conductively cooled from 160°C to 120°C to simulate the temperature dropped from a second flash system. The acid was introduced to arrest polymerization of silica (pH modification) in the brine. The chemical corrosion inhibitor was introduced right after cooling and the corrosion rates were monitored using corrosion probes. The experiment showed that Geogard 8822 corrosion inhibitor at 10 ppm concentration could inhibit corrosion of carbon steel pipes and lower the corrosion rate by as much as 70% at a temperature of ~120°C and at a pH range of~ 4.0 to 4.5.