Drilling history and evolution at Wairakei

Drilling of the Wairakei geothermal field began in May 1950. The rigs initially used were the small truck-mounted Sullivan 37 and Failing 1500 rigs that could drill to 130 and 460 m depth, respectively. These were augmented in November 1952 with two larger capacity rigs (National T12's) that were rated to about 1500 m. The Continental Emsco GC350 was acquired in 1968 to explore the deep geothermal resource—this rig could drill to about 2500 m depth.