Partial-SAGD Applications in the Jackfish SAGD Project

Abstract

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.