Permeability reduction in subterranean reservoirs

Claim 3

The method defined in claim 1 wherein the alkaline material is employed in a concentration of about 0.1 to 0.5 parts by weight of the aqueous solution or dispersion.

Claim 4

The method defined in claim 1 wherein the alkaline material is sodium hydroxide.

Claim 5

The method defined in claim 1 wherein the polymer is employed at a concentration of about 0.0025 to 1 parts by weight of the aqueous solution or dispersion.

Claim 6

The method defined in claim 1 wherein the polymer is employed at a concentration of about 0.02 to 0.5 parts by weight of the aqueous solution or dispersion.

Claim 7

The method defined in claim 1 wherein the cross-linking agent is employed at a concentration of about 0.0005 to 1 part by weight of the aqueous solution or dispersion.

Claim 8

The method defined in claim 1 wherein the cross-linking agent is employed at a concentration of about 0.01 to 0.2 part by weight of the aqueous solution or dispersion.

Claim 9

The method defined in claim 1 wherein the said polymer is a partially hydrolyzed polyacrylamide.

Claim 10

The method defined in claim 1 wherein the alkali metal aluminate is sodium aluminate.

Claim 11

The method defined in claim 1 wherein the reduction in permeability occurs about 20 feet or more away from the well.

Claim 12

The method defined in claim 1 wherein the injection of the said aqueous solution or dispersion is followed by injection of an acid gas selected from the group consisting of carbon dioxide, hydrogen sulfide, sulfur dioxide and sulfur trioxide.

Claim 15

The method defined in claim 12 wherein the alkali metal or ammonium hydroxide is employed in a concentration of about 0.1 to 0.5 parts by weight of the aqueous solution or dispersion.

Claim 16

The method defined in claim 12 wherein the alkali metal hydroxide is sodium hydroxide.

Claim 17

The method defined in claim 12 wherein the alkali metal aluminate is sodium aluminate.

Claim 18

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 2 to about 800 barrels per vertical foot of strata to be treated of a mixture of an aqueous solution or dispersion of (1) a water-soluble or water-dispersible 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, (2) a cross-linking agent for the polymer comprising a water-soluble salt of a polyvalent cation which reacts in solution to form a colloidal hydroxide selected from the group consisting of an alkali metal or ammonium aluminate or tungstate, and (3) an amount of a water-soluble alkaline material selected from the group consisting of alkali metal and ammonium hydroxides, alkali metal silicates, and alkali metal phosphates sufficient to raise the pH of the overall aqueous solution or dispersion to about 10 or above, passing the said aqueous solution or dispersion through the reservoir until the Ph has fallen to about 9 or below, and shutting in the well until the reservoir permeability has been reduced.

Claim 19

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 2 to about 800 barrels per vertical foot of strata to be treated of a mixture of an aqueous solution or dispersion of (1) a water-soluble or water-dispersible 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, (2) a cross-linking agent for the polymer comprising a water-soluble salt of a polyvalent cation which reacts in solution to form a colloidal hydroxide selected from the group consisting of an alkali metal or ammonium aluminate or tungstate, and (3) an amount of a water-soluble alkaline material selected from the group consisting of alkali metal and ammonium hydroxides, alkali metal silicates, and alkali metal phosphates sufficient to raise the pH of the overall aqueous solution or dispersion to about 10 or above, passing the said aqueous solution or dispersion through the reservoir until the Ph has fallen to about 9 or below, and shutting in the well until the reservoir permeability has been reduced.

Claim 20

The method defined in claim 16 wherein the alkaline material is employed in a concentration of about 0.1 to 0.5 parts by weight of the aqueous solution or dispersion.

Claim 21

The method defined in claim 16 wherein the alkaline material is sodium hydroxide.

Claim 22

The method defined in claim 16 wherein the polymer is employed at a concentration of about 0.0025 to 1 parts by weight of the aqueous solution or dispersion.

Claim 23

The method defined in claim 16 wherein the polymer is employed at a concentration of about 0.02 to 0.5 parts by weight of the aqueous solution or dispersion.

Claim 24

The method defined in claim 16 wherein the cross-linking agent is employed at a concentration of about 0.0005 to 1 part by weight of the aqueous solution or dispersion.

Claim 25

The method defined in claim 16 wherein the cross-linking agent is employed at a concentration of about 0.01 to 0.2 part by weight of the aqueous solution or dispersion.

Claim 26

The method defined in claim 16 wherein the said polymer is a partially hydrolyzed polyacrylamide.

Claim 27

The method defined in claim 16 wherein the alkali metal aluminate is sodium aluminate.

Claim 28

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 2 to about 800 barrels per vertical foot of strata to be treated of a mixture of an aqueous solution or dispersion containing (1) about 0.02 to 0.5 parts by weight of a partially hydrolyzed polyacrylamide, (2) about 0.01 to 0.2 part by weight of sodium aluminate cross-linking agent, and (3) about 0.1 to 0.5 part by weight of sodium hydroxide, passing the said aqueous solution or dispersion through the reservoir until its pH has fallen to about 9 or below, and shutting in the well until the reservoir permeability has been reduced.

Claim 29

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 2 to about 800 barrels per vertical foot of strata to be treated of a mixture of an aqueous solution or dispersion containing (1) about 0.02 to 0.5 parts by weight of a partially hydrolyzed polyacrylamide, (2) about 0.01 to 0.2 part by weight of sodium aluminate cross-linking agent, and (3) about 0.1 to 0.5 part by weight of sodium hydroxide, passing the said aqueous solution or dispersion through the reservoir until its pH has fallen to about 9 or below, and shutting in the well until the reservoir permeability has been reduced.