Waterflooding process
Gas was injected after a waterflood, forming a gas dispersion to preferentially carry the surfactants to the oil-water interface, for enhanced oil recovery. The increased mobility of the surfactant, due to the collection of the surfactant onto the gas bubbles, decreased the amount of adsorption of the surfactant onto the reservoir rock. Foams which would inhibit the high mobility of the dispersed gas were prevented by the use of a non-foam stabilizing surfactant or combination of surfactants, and by using a low gas-water volume ratio (1 : 9 to 1 : 1). An oil external micellar system was also created at the trailing edge of the oil bank, improving oil displacement efficiency. The oil-soluble gas, such as carbon dioxide, tends to dissolve into the oil bank, reducing the oil's viscosity, and improving the mobility of the oil bank. Packs of Ottawa sand (permeability to water of 21 darcies) were saturated with 0.2 N sodium chloride brine, flooded with filtered crude oil from the Second Wall Creek formation of Salt Creek field in Wyoming, and waterflooded. Using a micellar solution of sodium petroleum sulfonate, isopropyl alcohol and brine, 89 percent of residual oil from the first 25 inches of the packed core was recovered. The purging gas was carbon dioxide. The dispersed gas also tends to collect dispersed oil left by other surfactants, wetting agents and oil solvents.
- Assignee:
- Amoco Production Co.
- Patent Number(s):
- US 3817331
- OSTI ID:
- 7093264
- Country of Publication:
- United States
- Language:
- English
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