Method for improving the injectivity of water injection wells

Claim 1

The method defined in claim 1 wherein said soluble oil is comprised of a major proportion of liquid hydrocarbon, amounts of alkyl aryl sulfonate and partially oxygenated organic liquid stabilizing agent effective to form stable emulsions on the addition of water to the soluble oil, and less than about 10 volume percent water.

Claim 11

A method for increasing the injection rate of flood water into a porous subterranean oil-bearing reservoir having a vertical thickness in excess of about 30 feet and having strata differing in permeability by at least about 50 millidarcies penetrated by an injection well wherein the flow of flood water into the reservoir is restricted by residual oil in the reservoir immediately surrounding the injection well, which comprises: introducing into said injection well, in two to five successive increments alternated with low salt-content water containing less than about 1.0 weight percent total dissolved salts and less than 200 p.p.m. polyvalent cations, about 0.5 to 3 barrels of substantially anhydrous soluble oil per foot of vertical thickness of said reservoir said soluble oil comprising about 52 to 90 volume percent liquid hydrocarbons, about 4 to 30 volume percent alkyl aryl sulfonates about 0.5 to 8 volume percent partially oxygenated organic liquid stabilizing agent, and less than about 10 volume percent water, and said low salt-content water being introduced into said well in an amount equivalent to about 0.5 to 1 volume of water per volume of said immediately preceding increment of soluble oil; next introducing into said well about 1 to 4 volumes of said low salt-content water per total volume of said soluble oil introduced into said well; and thereafter injecting flood water through said injection well and into said reservoir.

Claim 12

A method for improving the injectivity of water into a porous subterranean oil-bearing formation having a vertical thickness in excess of about 30 feet and having strata differing in permeability by at least about 50 millidarcies penetrated by an injection well, which comprises: injecting water through said injection well and into said formation at a first injection rate; discontinuing the injection of said water; introducing into said injection well in two to five successive increments alternated with low salt-content water about 0.5 to 3 barrels of substantially anhydrous soluble oil per foot of vertical thickness of said reservoir, said low salt-content water being introduced into said well in an amount equivalent to about 0.5 to 1 volume of said water per volume of said immediately preceding increment of soluble oil; and thereafter injecting water through said injection well and into said reservoir at an injection rate higher than said first injection rate.