Abstract
Gas lift completions for steam-assisted gravity-drainage (SAGD)(1) producers
are unique. Conventional gas lift valves and mandrels with a packer completion
cannot be used because of the extreme temperatures of the downhole environment.
Most lift gas enters the production stream downhole through open-ended tubing
or nozzles, which if not properly sized can result in operational issues such
as fluid/gas slugging and pressure instabilities that negatively impact the
overall lift efficiency.
In 2006, ConocoPhillips conducted a study to design a gas lift system for
the Surmont SAGD development that would allow better control of lift gas into
the production string. In late 2007, the wells completed with gas lift were
placed on production. This paper covers the data-collection effort and analysis
completed to determine the efficiency of the two types of gas lift nozzles used
in the completions, the methodology for optimization of SAGD gas-lift systems,
and recommendations for future improvement.
Background
Surmont, an in-situ oil-sands project, is located approximately 60 km
southeast of Fort McMurray in the Athabasca oil sands (Figure 1). This
multiphase SAGD project is a 50:50 joint venture between ConocoPhillips Canada
Ltd. (CPC) and Total E&P Canada Ltd., with CPC as the operator. The Surmont
pilot began injection of steam in 1997. The pilot comprises three SAGD well
pairs that use a variety of artificial-lift methods. These wells have been
tested to determine the preferred method of artificial lift for the first
commercial phase.
Steam injection, for Phase 1A of the commercial development, was initiated
in mid-2007. Conversion to full SAGD production followed in late 2007. Phase 1A
comprises 20 well pairs in which all the producers have been completed to
produce through gas lift for the initial life of the well. Phase 1 (A, B, and
C) has a capacity of 3,975 m3/d (25,000 B/D) and is expected to reach peak
production in 2012. A second phase is slated for commercial startup before the
middle of the next decade. Upon completion and full ramp-up, it is estimated to
bring peak production from both phases to 15,899 m3/d (100,000 B/D). Additional
phases at Surmont are also under study.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
6 August 2008
- Meeting paper published:
23 October 2008
- Revised manuscript received:
15 October 2008
- Manuscript approved:
28 September 2009
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