| Abstract |
Recent work in several New Zealand geothermal fields has shown severe casing deterioration on wells only 12-15 years old. Casings have been examined using Otis casing caliper, Kinley microscopic caliper, Schlumberger ETT-A (Electromagnetic Thickness Tool) and (Cement Bond) logs, flow logs and pressure tested using casing packers. the corrosion products indicates that attack commences at the outer surface, limiting the effectiveness of mechanical casing caliper techniques. The electromagnetic thickness tool has been successful in identifying zones of severe corrosion |