Summary
With steam-assisted-gravity-drainage (SAGD) operations, there will be times
that the producer downhole temperature falls below the desired level. This
situation may occur when a shut-in is required because of facility or well
operational issues. Cooling bitumen and steam condensate, which continue to
drain and raise the liquid level over the producer, cause difficulties with the
restart. The producer could also cool if the well pair is converted prematurely
from circulation to full SAGD mode.
A variety of artificial-lift technologies have been applied in field
applications. However, with its dual-tubing-completion design and gas lift
system, Devon has successfully used partial SAGD methods to optimize restart
strategies and effectively deal with times when the producer unexpectedly
cools.
This paper describes three SAGD operating modes used by Devon at Jackfish:
full SAGD, semi-SAGD, and partial SAGD. During partial SAGD, the fluid return
from the injector stops while steam injection continues down either the long
tubing (LT), short tubing (ST), or the annulus. The producer continues to be
circulated with the appropriate steam-injection rate into the LT and fluid
returns up the ST. Numerical-simulation results associated with partial SAGD
are presented. Partial-SAGD applications at the Jackfish SAGD project are
discussed.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
7 April 2009
- Meeting paper published:
17 June 2009
- Revised manuscript received:
10 May 2011
- Manuscript approved:
13 May 2011
- Version of record:
1 November 2011
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