Addition of monovalent salts for improved viscosity of polymer solutions used in oil recovery applications

Patent metadata

Field	Value
Publication number	US-10513652-B2
Application number	US-201715660420-A
Country	US
Kind code	B2
Filing date	Jul 26, 2017
Priority date	Jul 26, 2016
Publication date	Dec 24, 2019
Grant date	Dec 24, 2019

Abstract

An oil recovery composition having a brine, a hydrolyzable polymer, and a monovalent cations to divalent cations ration in the range of about 3:1 to about 4.5:1 is provided. An oil recovery composition may be formed from a brine recovered from production water and a polymer. A monovalent salt may be added to the brine recovered from production water to form a modified brine and achieve a modified monovalent cations to divalent cations ratio in the range of about 3:1 to about 4.5:1. Processes for forming the oil recovery composition and enhanced oil recovery using the oil recovery composition are provided.

First claim

What is claimed is:

1. A method of enhancing oil recovery in a hydrocarbon reservoir formation, comprising:
adding a monovalent salt to a brine to modify a mass ratio of monovalent cations to divalent cations of the brine, thereby forming a modified brine having a modified monovalent cations to divalent cations mass ratio in a range of range of 2.5:1 to 3:1, the modified brine having a Na + concentration in the range of 22,166 milligrams/liter (mg/L) to 30.624 mg/L;
introducing an oil recovery composition into the reservoir formation, the oil recovery composition comprising:
the modified brine having the modified monovalent cations to divalent cations mass ratio, the modified monovalent cations to divalent cations mass ratio selected to achieve a target viscosity of the oil recovery composition; and

polyacrylamide having a concentration of 0.05 weight (wt) % to 0.5 wt %.

2. The method of claim 1 , wherein the monovalent cations comprise sodium cations.

3. The method of claim 1 , wherein the divalent cations comprise at least one of calcium cations and magnesium cations.

4. The method of claim 1 , wherein the target viscosity comprises at least 4 centipoise at the conditions of the hydrocarbon reservoir formation.

5. The method of claim 1 , comprising preparing the oil recovery composition before introducing the oil recovery composition into the reservoir formation, the preparing comprising:
recovering the brine from production water;
adding the monovalent salt to the brine to form the modified brine; and
adding the hydrolyzable polymer to the brine.

6. The method of claim 1 , wherein the brine comprises treated seawater or untreated seawater.

7. The method of claim 1 , wherein the brine comprises aquifer water.

8. The method of claim 1 , wherein the oil recovery composition comprises a surfactant.

Assignees

• Saudi Arabian Oil Co

Inventors

• Hassan Saleh F
• Alsofi Abdulkareem M

Classifications

• C09K8/57

  Compositions based on water or polar solvents (C09K8/565 takes precedence) · CPC title

• C09K8/588 Primary

  characterised by the use of specific polymers {(polymeric surfactants C09K8/584)} · CPC title

• C08F220/56

  Acrylamide; Methacrylamide · CPC title

• G01N11/00

  Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties · CPC title