Plugging high permeability zones of reservoirs having heterogeneous permeability
AssigneeUnion Oil Company of California
InventorBurton B. Sandiford
Life of this patent
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Abstract
A method of forming a mixed plug in the more permeable zones of a subterranean reservoir of nonuniform permeability in which there is injected into the reservoir aqueous solutions of: a polymer, a material that reacts with the polymer to form a time-delayed polymer-containing plug, an alkali metal silicate and a material that reacts with the silicate to form a time-delayed silicate-containing plug. The injected solutions are either admixed at the surface prior to injection or are simultaneously injected so that a mixed polymer-silicate plug is formed in the reservoir.
Claims30
A method for reducing the permeability of the higher permeability strata or channels of a heterogeneous subterranean reservoir penetrated by a well comprising simultaneously injecting through said well and into said reservoir about 5 to 500 barrels per vertical foot of strata to be treated of a mixture of the following compositions:
- a. about 10 to 90 percent by volume of an aqueous solution or dispersion of a relatively high molecular weight polymer selected from the group consisting of acrylic acid-acrylamide copolymers, polyacrylamides, partially hydrolyzed polyacrylamides, polyalkyleneoxides, carboxyalkylcelluloses, hydroxyethylcelluloses and heteropolysaccharides obtained by the fermentation of starch-derived sugar,
- b. a cross-linking amount of an aqueous solution of a cross-linking agent for polymer selected from the group consisting of mixtures of a compound of a multivalent metal and a reducing agent, a low molecular weight watersoluble aldehyde, and a water-soluble salt of a polyvalent cation which reacts in solution to form a colloidal hydroxide,
- c. about 90 to 10 percent by volume of an aqueous solution of an alkali metal silicate, and
- d. a gelling amount of an aqueous solution of a gelling agent for silicate selected from the group consisting of acid and acid-forming compounds, watersoluble ammonium salts, lower aldehydes, aluminum salts and alkali metal aluminates, and
- shutting in the well until a mixed polymer-silicate plug has formed.
In a method for the recovery of oil from a subterranean oil reservoir having strata of heterogeneous permeability and which is in communication with at least one producing well and at least one injection well, which method includes injection into the reservoir of a secondary or a tertiary recovery fluid via an injection well and recovery of oil via a production well, the improvement which comprises, at some point during the injection of the secondary or tertiary recovery fluid, introducing into the heterogeneous reservoir from about 5 to about 500 barrels per vertical foot of strata to be treated of a mixture of:
- a. about 10 to 90 percent by volume of an aqueous solution of a relatively high molecular weight polymer selected from the class consisting of acrylic acidacrylamide copolymers, polyacrylamides, partially hydrolyzed polyacrylamides, polyalkyleneoxides, carboxyalkylcelluloses, hydroxyethylcelluloses and heteropolysaccharides obtained by the fermentation of starch-derived sugar,
- b. a cross-linking amount of an aqueous solution of a cross-linking agent for polymer selected from the class consisting of mixtures of a compound of a multivalent metal and a reducing agent, a low molecular weight water-soluble aldehyde, and a water-soluble salt of a polyvalent cation which reacts in solution to form a colloidal hydroxide,
- c. about 90 to 10 percent by volume of an aqueous solution of an alkali metal silicate, and
- d. a gelling amount of an aqueous solution of a gelling agent for silicate selected from the group consisting of acid and acid-forming compounds, water-soluble ammonium salts, lower aldehydes, aluminum salts and alkali metal aluminates, and
- shutting in the well until a mixed polymer-silicate plug has formed.
Dependencies are inferred from the claim text.