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U.S. Department of Energy
Office of Scientific and Technical Information

Miscible oil recovery process

Patent ·
OSTI ID:7299636
Surfactant adsorption during waterflooding can be substantially reduced by employing a preflush consisting of an aqueous solution of water soluble quaternary ammonium salt, such as tetramethylammonium chloride, in an amount sufficient to satisfy substantially all of the adsorption capacity of the formation matrix. The preflush is followed by injection of a surfactant. Any type of surfactant is satisfactory--anionic, nonionic, or cationic; however, nonionic surfactants, such as ethylene oxide adduct of nonyl phenol, is preferable. A small amount of the sacrificial material plus sodium chloride may be added to the surfactant for further protection. Slug viscosity can be increased by the addition of polymers which will also be protected from adsorption by the sacrificial material. Laboratory tests performed in silica sand indicated that the preflush slug is extremely effective in reducing surfactant adsorption.
Assignee:
Texaco Inc.
Patent Number(s):
US 3797574
OSTI ID:
7299636
Country of Publication:
United States
Language:
English