| Abstract |
This paper reviews the development of downhole logging equipment capable of operating at temperatures up to 330¢ªC in New Zealand over the last 60 years. During the initial period of development there were no off-the-shelf solutions and downhole tools were developed in New Zealand. Instruments to accurately measure downhole temperatures were in use within a year of completing the first wells at Wairakei in 1951 and mechanical downhole pressure gauges were introduced in 1958. Since that time equipment and logging methods have gradually improved, with the introduction of surface readout temperature-spinner logging in 1966 and onwards to simultaneous pressure-temperaturespinner logs in 1995. Probably the most significant improvement was the introduction of downhole memory PTS tools, capable of being run using a small wireline winch, in 2000. By 2003 this method had superseded mechanical PT tools for all routine logs. Since then the reliability and capability of downhole logging has gradually improved with advances in electronics and technology. High temperature PTS logging tools can now be purchased from several different manufacturers. The current MB Century PTS tool provides a cost-effective solution with very high reliability and technical capability and specification sufficient for most geothermal logging programs. MB Century have also developed a robust high temperature casing condition electronic monitoring tool to detect internal and external casing corrosion without the need to quench wells that is not available elsewhere. |