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

Multistage waterflood

Patent ·
OSTI ID:6303029
In a method of recovering oil by multistage waterflooding, low interfacial tensions are achieved between the oil being displaced and the flooding water. In the process, a first slug of form 0.01-10% pore volume of an aqueous nonsaline solution containing a first concentration of a surfactant is injected which is at least partially water-soluble and preferentially oil-soluble. This is followed by a second slug of from 0.01-10% pore volume of an aqueous saline solution containing a second and lower concentration of the surfactant. Finally, a third slug is injected of at least 5.0% pore volume of brine to drive the nonsaline solution, the saline solution, and the oil toward the production well. Each slug of the nonsaline solution, of the saline solution, and of the brine is injected into the formation one time each. The cycle of slug injection may be repeated one or more times, if economical, to achieve a wider distribution of the low interfacial tension between the oil and the water or more nearly completely recover the oil from the formation. (6 claims)
Assignee:
Mobil Oil Corp.
Patent Number(s):
US 3346047
OSTI ID:
6303029
Country of Publication:
United States
Language:
English