Summary
Two of the most important artificial-lift methods applied in oil wells are
sucker-rod pumping (SRP) and electrical submersible pumping (ESP, with
thousands of installations all over the world. Their operational features and
application ranges are quite different, but in many cases either of them can be
used in a given well. The final selection of the proper method has to be on the
basis of energy efficiency, and the one requiring the least amount of surface
power input is selected. This paper provides the necessary background for
evaluating the effectiveness of the two lift methods investigated and for
pinpointing the requirements of achieving maximum power efficiency of
artificial lifting.
The power flow in the pumping system is investigated, and the sources of
power losses, along with their usual ranges, are described. The overall power
efficiency of the system is defined by a simple formula that provides the
necessary insight into the main components of the power losses occurring in
different system elements. A thorough investigation of the efficiency
components allows one to find the factors that most markedly influence the
total system's power requirement. As shown in the paper, the most important
requirement for achieving maximum effectiveness is the proper choice of the
pumping mode (i.e., the combination of plunger size, stroke length, and pumping
speed).
The calculation of energy losses in the components of the ESP system is
detailed, and the relative importance of the individual losses is shown.
Because the components of the ESP system are connected in series, a relatively
simple formula can be used to describe the effect of electrical and hydraulic
losses on the efficiency of the total system. The terms of the final formula
were investigated for their importance and contribution to the overall
effectiveness of the ESP system. Results of this investigation provide crucial
information that explain how to design an ESP system that provides the highest
power efficiency.
The practical use of the proposed calculation models is illustrated by
presenting an example case where a relatively high liquid rate (1,300 B/D) from
the same well is produced by rod pumping and by ESP. Detailed installation
designs resulted in several different operation modes for both SRP and ESP. The
paper demonstrates that using the latest technologies (e.g., high-strength
sucker-rod connections), SRP can compete successfully with ESP installations by
attaining higher energy efficiencies.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
13 September 2010
- Meeting paper published:
2 November 2010
- Revised manuscript received:
5 January 2011
- Manuscript approved:
8 January 2011
- Published online:
29 March 2011
- Version of record:
1 April 2011
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