The quest for energy is leading the industry into drilling deeper wells. Typically, a
temperature gradient of 1°C/150 ft can be expected, with bottom hole temperatures
reaching beyond 200°C in many areas of the world. Moreover, the increased recovery
benefits and cost reductions possible with the use of horizontal and multilateral wells has
triggered a need for higher power energy conversion systems in bottom hole assemblies,
such as rotary steerable tools and downhole tractors. The concepts developed
throughout this work address some of these new needs.
This research investigated improvements, novel solutions and considerations that
will lead to significant advantages in terms of reliability, extended temperature
operation, increased power capability and reduced size and cost of compact harsh
environment energy conversion systems. Improvements to both the electromechanical
subsystem and the power electronic subsystem are introduced.
Air gap viscous losses were shown to a have a significant effect on the optimal
design of submersible PM (permanent magnet) machines, and a design procedure to account for this loss component in the design was developed. The application of a dual
winding exterior rotor PM machine in a downhole environment enabled a significant
increase in the application’s torque capability, provided protection against generator
winding over voltage, and reduced parts count. Comprehensive switching device
qualification, testing, and simulation lead to a simple failure mitigation technique for the
operation of the most suitable devices at elevated temperature. A flying capacitor
multilevel inverter was then successfully constructed and temperature tested. A novel
motor drive concept suited for elevated temperature oil filled environment applications
concluded the research.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1289 |
| Date | 15 May 2009 |
| Creators | Ahmed, Shehab |
| Contributors | Toliyat, Hamid |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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