Deep drilling technology allows previously unreachable oil reserves to be opened up, with drilling depths of 5000 metres and drill lengths of up to 11 000 metres.
However, the requirements on the materials used are very high. The temperatures and pressures at these depths, combined with the strong vibrations that occur during the drilling procedure, present unique challenges to the use of electronic drives. Robust materials that remain 100% reliable at temperatures of up to 200°C are required. maxon motor’s EC22 HD heavy duty motor fulfils all requirements for these extreme conditions.
The electronically commutated motor, which has been designed for the exceptionally high requirements of deep drilling, can withstand harsh conditions in which other motors would fail. The turbine in the drilling tool is driven by mud flow. Through the use of a magnetic coupling, motors become generators and supply the electrical energy for various drive functions, so no batteries are needed. With the aid of the EC22 HD, the position of the drill head can be measured and aligned dynamically during the drilling process by means of accelerometers and inclination sensors. maxon’s MWD technology converts the data to pulses that are sent to the drill platform. This system is driven by electromagnets or HD motors. Diverse deep drilling tools also use hydraulic valves or flaps that are operated by electromechanical drives.
Many applications, especially in the field of deep drilling, require a robust gearhead that accurately fulfils the requirements. Most underground applications require very high torques, sometimes for only very short durations (valve control, moving flaps). A special property of the gearhead is the integrated drill holes that are necessary for an unhindered oil flow, because the gearhead, just like the motor, can be operated in oil. The different versions of the EC 22 are optimised either for operation in air or in oil.
The motors are constructed without adhesives and do not have a mechanical commutation system. This enables them to withstand extreme temperatures and also ensures constant performance under ultrahigh vacuum conditions. The power rating depends on the surrounding medium and amounts to 80 W in air and, due to the much larger heat dissipation, 240 W in oil. The motors have been designed for ambient temperatures of more than 200°C and atmospheric pressures of up to 1700 bar. If the motors are cooled with oil, they can even withstand temperatures up to 240°C. Other requirements on the motors, which have a diameter of 22 mm, are resistance against vibrations of up to 25 Grms, as well as against impacts of up to 100 times the gravitational acceleration of the earth. In comparison, Formula 1 race cars reach 2 G and fighter jets up to 13 G. A human can withstand about 10 G.
In addition to its very high resistance to the extreme ambient conditions at great depths, the maxon HD motors also have a very high efficiency, with up to 88% being reached in air and more than 70% in oil.
For more information contact Hans Burri, DNH Tradeserve, +27 (0)11 468 2722, hans.burri@dnhtrade.co.za, www.dnhtrade.co.za
| Tel: | +27 11 468 2722/4127 |
| Fax: | +27 86 509 6714 |
| Email: | info@dnhtrade.co.za |
| www: | www.dnhtrade.co.za |
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