Secondary recovery process using surfactant mixtures
A method to minimize surfactant adsorption in secondary or tertiary recovery of oil involves injecting (1) a preflush, (2) a saline aqueous slug containing a nonionic surfactant and an anionic surfactant, and (3) a displacing fluid such as water or brine or thickened water or brine. The preflush is employed to minimize adsorption of the surfactants and may be water, brine, thickened water or brine or an aqueous solution of either inorganic salts or adsorption reducing additives. The surfactant must contain both a nonionic and an anionic variety. By using these two different surfactants, a synergistic effect occurs which performs more effectively than either one acting separately in lowering interfacial tension, reducing adsorption, improving wettability, and raising tolerance for electrolyte. The surfactants used in laboratory tests on crushed limestone cores were the nonionic commercial variety, Tergitol NP-27 (ethoxylated nonyl phenol) and the anionic commercial surfactant Pyronate 50 (petroleum sulfonate-sodium salt). Dow Pusher 700 thickening agent is added to the surfactant slug. Recoveries measured in pore volumes of oil indicated that a significant reduction of adsorption can be obtained using a specified salinity and the nonionic--anionic surfactant combination.
- Assignee:
- Texaco Inc.
- Patent Number(s):
- US 3792731
- OSTI ID:
- 7299635
- Country of Publication:
- United States
- Language:
- English
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