Surfactant oil recovery process usable in formations containing water having high concentrations of polyvalent ions such as calcium and magnesium
This process for tertiary recovery of oil following conventional waterflooding involves the use of a dual surfactant system employable in the presence of from 500 to 9,000 ppm polyvalent ions, such as calcium and/or magnesium. The two components of the surfactant are (1) a water soluble salt of an alkyl or alkyl aryl sulfonate or phosphate wherein the alkyl chain has from 5 to 25 carbon atoms and (2) a nonionic surfactant such as a polyethoxylated aliphatic alcohol. This process involves injection of a preflush of sacrificial inorganic material such as sodium carbonate or sodium polyphosphate or of more than the optimum concentration of surfactant, followed by injection of the dual surfactant solution with polymer additive for improved sweep efficiency, next a mobility buffer of polyacrylamide or polysaccharide polymer, and finally injection of water which will drive the previous solution plus oil to a producing well. Waterflood testing was performed on cores from the San Andres dolomite formation, Bob Slaughter field, Hockley County, Texas, and capillary displacements tests were run on simulated connate water from the same field. It has been proposed that recoveries could range up to 72 percent utilizing the dual surfactant system.
- Assignee:
- Texaco Inc.
- Patent Number(s):
- US 3811505
- OSTI ID:
- 7215990
- Country of Publication:
- United States
- Language:
- English
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Surfactant oil recovery process
Surfactant oil recovery process usable in formations containing water having high concentrations of polyvalent ions such as calcium and magnesium