Summary
Coinjecting solvent with steam under steam-assisted gravity-drainage (SAGD)
process to reduce the required steam amount for heavy-oil production has gained
importance in recent years. The objective of this experimental study was to
investigate the drainage mechanism of coinjecting light and heavy solvents to
improve production performance.
A 2D cross-sectional low-pressure scaled physical model was constructed. The
model represented a half-symmetry cross section of a typical SAGD drainage in
the Athabasca formation. Using an infrared camera, we visualized and recorded
expansion of the steam chamber and temperature distribution. The fluid
injection rate, pressure, and temperature, and produced-liquid volumes were
also recorded.
The results show that the relative condensation time of solvent and steam
results in different production performances. Light solvent, delivered in the
vapour phase to the entire fluid interface, reduces the bitumen viscosity along
the whole vapour-chamber boundary, but it may build a thick gas blanket that
may reduce the heat transfer from the high-temperature vapour chamber to the
surrounding low-temperature bitumen. Coinjecting a suitable
multicomponent-solvent mixture, including a heavy solvent, can enhance the
production performance by altering the condensation dynamics of the light
hydrocarbons.
The conclusions from this study can be used to design suitable solvent
mixtures and coinjection strategies to deliver a higher production rate, higher
recovery factor with lower cumulative steam required/oil ratio (CSOR), and
lower cumulative energy required for oil production (CEOR) from SAGD
performance.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
29 June 2010
- Meeting paper published:
21 September 2010
- Revised manuscript received:
31 December 2010
- Manuscript approved:
8 January 2011
- Published online:
29 March 2011
- Version of record:
1 April 2011
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