SPE Journal
Volume 17,
Number 2,
June 2012,
pp. 326-334
Summary
The aim of this work is to evaluate alkaline/surfactant (AS) methods to
improve recovery from heavy-oil reservoirs. Alkali/surfactant/oil
phase-behavior experiments were conducted to determine conditions under which
oil-in-water (O/W) emulsions form. The viscosity (and its shear dependence) was
measured for some of these emulsions. Reservoir sand was assembled in
sandpacks. Waterflood and AS floods were conducted at several salinities.
Several relatively hydrophilic surfactants were identified, which formed O/W
emulsions with the reservoir oil at a low concentration in the presence of
sodium carbonate. O/W emulsions were favored at low salinity and high water/oil
ratio (WOR). Viscosity of these emulsions was low compared with the oil
viscosity. Waterflood recovery was on the order of 25 to 40% of the original
oil in place (OOIP) in corefloods, and it decreased as the injection rate
increased. Following the waterflood, the AS flood gave an incremental oil
recovery of 10 to 35% of OOIP. The incremental post-breakthrough oil recovery
during the waterflood is likely because of the imbibition of the water from
viscous fingers into the unswept oil-saturated zone; this recovery is directly
proportional to the square root of time.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
1 January 2011
- Meeting paper published:
25 April 2010
- Revised manuscript received:
27 July 2011
- Manuscript approved:
2 September 2011
- Published online:
23 March 2012
- Version of record:
11 June 2012