Downhole sensor operates at temperatures hotter than Venus

Paul Boughton

Zenith Oilfield Technology Limited is announcing tests on new technology set to monitor well pressure and temperatures up to 500˚C. which is hotter than planet Venus.

A white paper on the trailblazing XT system will be launched next month (June 14th) at a Society of Petroleum Engineers conference in Barcelona, detailing plans to operate at temperatures 20˚C hotter than Venus.
The company, which formed in 2004, designs, develops, manufactures and supports leading edge technology to gather and analyse downhole data.
Zenith’s current HT (Hi Temp) system is already extending permanent downhole monitoring system’s temperature limitations. The system has been field proven in the Middle East, operating reliably at temperatures of 247˚C.
To further advance high temperature technology boundaries, Zenith is soon to release its new XT extreme temperature system, which uses new state of the art ceramic insulation. The prototype systems have been successfully tested at over 500˚C.
Greg Davie, Managing Director of Aberdeenshire based Zenith believes the new technologies will dramatically improve the reliability of monitoring high temperature oil wells in the future.
He said: “This technology overcomes the historic problem of monitoring steam flood operations and also HPHT wells as the gauges available have short life spans and give erroneous results. We now have robust technology that performs at high temperatures which will ultimately improve production and reservoir drainage.”
Downhole reservoir monitoring gauges have been in development since the Schlumberger brothers started in the 1930s and by the 1970s operators were using gauges for permanent monitoring of well bore pressures. But, there has long been a need for these gauges to operate at higher temperatures to allow continuous monitoring of either naturally hot reservoirs or wells where heat is applied to assist production.
Current permanently installed electronic technology was shown to only extend to 175˚C and life expectancy was very low. Zenith set about the challenge in 2007, looking at cable, electrical connections and pressure seals to obtain a complete high temperature system.
Zenith’s first 400C prototype XT sensor - from a well installed in July 2009 -  is still alive, with further installations planned for this year.
A new pressure sensor had to be developed for this application, which is a molecular bonded micromachined sensor, constructed of ceramic monocrystalline Sillicone and Pyrex.
The cable also had to be revised and Zenith developed a new unique ceramic insulation, resulting in one of the only permanent 500 Celsius down hole cables in the world.
Davie added: “A big hurdle in testing the technology, was that a calibration system that could operate at those temperatures did not exist, so we overcame this by developing a precision 5,000 psi 500˚C computer controlled calibration system, which is gas based.”
New prototypes which are in test have been seen to operate at over 600 Celsius and Zenith now has a full calibration and test facility in place in the UK.
Davie said: “We have succeeded in extending the existing technology and gone on to develop a 500˚C pressure sensor with cable, housings and connections. We are very optimistic that we will achieve a fully successful 500˚C well trial this year and are now looking at HPHT applications up to 20,000 psi.”
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