Oil recovery process and system

Claim 2

A process for producing a partially hydrolyzed polyacrylamide having a preselected average molecular weight and molecular weight distribution for use in recovering oil from a subterranean oil-bearing formation, comprising: predetermining the injectivity and mobility properties of a partially hydrolyzed polyacrylamide required to meet the oil displacement demands of an oil-bearing formation by obtaining a core sample from the formation and subjecting the sample to tests simulating the passage of the partially hydrolyzed polyacrylamide through the formation during oil displacement; forming a solution of a water soluble acrylamide monomer capable of being polymerized; polymerizing said monomer in the presence of a polymerization catalyst, the proportion of catalyst present being regulated during polymerization to provide, an acrylamide polymer having an average molecular weight of about 2 million to about 10 million and a molecular weight distribution of about 0.02 to about 0.22 as determined by the ratio σ/M where σ is the standard deviation of molecular weight of abundance of a molecular species present in the polymer and M is the average molecular weight of the polymer; contacting said polymer with a hydrolyzing agent in an amount to effect partial hydrolyzation of the polymer while maintaining the predetermined average molecular weight and molecular weight distribution of the polymer; and forming an aqueous solution of the partially hydrolyzed polyacrylamide in a concentration to enable the partially hydrolyzed polyacrylamide to be injected into the oil-bearing formation.

Claim 3

A process according to claim 1 wherein the catalyst comprises a mixture of an alkali metal persulfate and an alakali metal bisulfite.

Claim 4

A process according to claim 2 wherein the alkali metal persulfate is ammonium persulfate and the alkali metal bisulfite is sodium bisulfite, the ratio of the persulfate to the bisulfite being of the order of about 9:1 to about 1:9.

Claim 5

A process according to claim 2 wherein the catalyst further includes a ferrous compound.

Claim 6

A process according to claim 4 wherein the ferrous compound is ferrous ammonium sulfate.

Claim 7

A process according to claim 1 wherein the hydrolyzing agent is added in an amount sufficient to hydrolyze from about 20 to about 40 percent of the polyacrylamide polymer.

Claim 8

A process according to claim 6 wherein the hydrolyzing agent is an aqueous solution of an alkali metal hydroxide.

Claim 9

A process according to claim 1 wherein the aqueous solution of the partially hydrolyzed polyacrylamide has a reciprocal relative mobility in the range of from about 1 cp to about 1,000 cp.

Claim 10

A process according to claim 1 wherein the concentration of the partially hydrolyzed polyacrylamide in the aqueous solution is about 50 to about 5,000 ppm.

Claim 11

A partially hydrolyzed polyacrylamide prepared in accordance with the process of claim 1.

Claim 12

A polymer solution consisting essentially of a partially hydrolyzed polyacrylamide prepared in accordance with the process of claim 1.

Claim 13

A process for producing a partially hydrolyzed polyacrylamide having properties such that it is capable in solution of selectively meeting the conditions for promoting, enhancing and controlling the displacement and/or flow of fluids in subterranean oil-bearing formations, comprising: predetermining the injectivity and mobility properties of a partially hydrolyzed polyacrylamide required to meet the oil displacement demands of an oil-bearing formation by obtaining a core sample from the formation and subjecting the sample to tests simulating the passage of the partially hydrolyzed polyacrylamide through the formation during oil displacement; forming a solution of a water soluble acrylamide monomer capable of being formed into an acrylamide polymer; polymerizing said monomer in the presence of a polymerization catalyst, the concentration of the catalyst being regulated during polymerization to provide an acrylamide polymer having an average molecular weight of about 2 million to about 10 million and a molecular weight distribution of about 0.02 to about 0.22 as determined by the ratio σ/M where σ is the standard deviation of molecular weight of abundance of a molecular species present in the polymer and M is the average molecular weight of the polymer; contacting said polymer with a hydrolyzing agent in an amount to effect partial hydrolyzation of the polymer while maintaining said average molecular weight and molecular weight distribution of the polymer; and forming a solution of the resulting partially hydrolyzed polyacrylamide to provide a concentration of said polyacrylamide in the solution sufficient to promote, enhance and control the displacement and/or flow of a fluid in the subterranean oil-bearing formation.

Claim 14

A process for producing a partially hydrolyzed polyacrylamide having properties such that it is capable in solution of selectively meeting the conditions for promoting, enhancing and controlling the displacement and/or flow of fluids in subterranean oil-bearing formations, comprising: predetermining the injectivity and mobility properties of a partially hydrolyzed polyacrylamide required to meet the oil displacement demands of an oil-bearing formation by obtaining a core sample from the formation and subjecting the sample to tests simulating the passage of the partially hydrolyzed polyacrylamide through the formation during oil displacement; forming a solution of a water soluble acrylamide monomer capable of being formed into an acrylamide polymer; polymerizing said monomer in the presence of a polymerization catalyst, the concentration of the catalyst being regulated during polymerization to provide an acrylamide polymer having an average molecular weight of about 2 million to about 10 million and a molecular weight distribution of about 0.02 to about 0.22 as determined by the ratio σ/M where σ is the standard deviation of molecular weight of abundance of a molecular species present in the polymer and M is the average molecular weight of the polymer; contacting said polymer with a hydrolyzing agent in an amount to effect partial hydrolyzation of the polymer while maintaining said average molecular weight and molecular weight distribution of the polymer; and forming a solution of the resulting partially hydrolyzed polyacrylamide to provide a concentration of said polyacrylamide in the solution sufficient to promote, enhance and control the displacement and/or flow of a fluid in the subterranean oil-bearing formation.

Claim 15

A process according to claim 12 wherein the concentration of the partially hydrolyzed polyacrylamide in the solution is about 50 to about 5,000 ppm.

Claim 16

A partially hydrolized acrylamide prepared in accordance with the process of claim 12.

Claim 17

A polymer solution consisting essentially of a partially hydrolyzed polyacrylamide prepared in accordance with the process of claim 12.