Delayed gelation polymer system for high temperature and high salinity applications

Patent metadata

Field	Value
Publication number	US-12049588-B2
Application number	US-202318129662-A
Country	US
Kind code	B2
Filing date	Mar 31, 2023
Priority date	Dec 4, 2019
Publication date	Jul 30, 2024
Grant date	Jul 30, 2024

Abstract

This disclosure describes the composition and methods of use for a novel delayed polymer gelation system for high temperature and high salinity applications. This polymer gelation system includes a polymer of acrylamide, AMPS and 500-5000 ppm polyethylene glycol diacrylate in inverse emulsion form, and a polyethyleneimine (PEI) with a MW of 2,000-30,000 daltons as the crosslinking agent.

First claim

What is claimed is:

1. A polymer system comprising:
a polymer comprising:
acrylamide;
2-acrylamido-2-methylpropane sulfonic acid (AMPS);
polyethylene glycol diacrylate; and
sodium formate;

a crosslinker comprising polyethyleneimine; and
a temperature stabilizer;
wherein the polymer is in inverse emulsion form.

2. The polymer system of claim 1 wherein the polymer is at a concentration of about 25-35%.

3. The polymer system of claim 1 wherein the polymer comprises:
about 50-90% acrylamide;
about 10-50% AMPS;
about 500-5000 ppm polyethylene glycol diacrylate; and
about 100-2000 ppm sodium formate;
wherein the crosslinker comprises about 100-1500 ppm polyethyleneimine.

4. The polymer system of claim 3 wherein the polymer comprises:
about 80% acrylamide;
about 20% AMPS;
about 500 ppm polyethylene glycol diacrylate; and
about 400 ppm sodium formate;
wherein the crosslinker comprises about 1200 ppm polyethyleneimine.

5. The polymer system of claim 3 wherein the polymer comprises:
about 60% acrylamide;
about 40% AMPS;
about 500 ppm polyethylene glycol diacrylate; and
about 400 ppm sodium formate;
wherein the crosslinker comprises about 200 ppm polyethyleneimine.

6. The polymer system of claim 1 wherein the crosslinker comprises polyethyleneimine at a molecular weight of about 2,000-30,000 daltons.

7. The polymer system of claim 6 wherein the polyethyleneimine has a molecular weight of about 10,000 daltons.

8. The polymer system of claim 1 wherein the temperature stabilizer comprises about 0.02-0.1 wt % thiourea.

9. The polymer system of claim 1 wherein the viscosity of the polymer system is about 1-10 cp before gelation.

10. The polymer system of claim 1 wherein the polymer system undergoes gelation at a temperature between about 80-130 degrees Celsius and wherein the polymer gel is formed in a brine with total dissolved solids in the range of about 50,000 mg/L to 200,000 mg/L.

11. A method of improving sweep efficiency for an oil-bearing zone comprising:
preparing a polymer system comprising:
a polymer comprising:
acrylamide;
2-acrylamido-2-methylpropane sulfonic acid (AMPS);
polyethylene glycol diacrylate; and
sodium formate;

a crosslinker comprising polyethyleneimine; and
a temperature stabilizer;
wherein the polymer is in inverse emulsion form; and

injecting the polymer system into a wellbore to improve the sweep efficiency.

12. The method of claim 11 wherein the polymer is at a concentration of about 25-35% in the inverse emulsion.

13. The method of claim 11 wherein the polymer comprises
about 50-90% acrylamide;
about 10-50% AMPS;
about 500-5000 ppm polyethylene glycol diacrylate; and
about 100-2000 ppm sodium formate;
wherein the crosslinker comprises about 100-1500 ppm polyethyleneimine.

14. The method of claim 13 wherein the polymer comprises
about 80% acrylamide;
about 20% AMPS;
about 500 ppm polyethylene glycol diacrylate; and
about 400 ppm sodium formate;
wherein the crosslinker comprises about 1200 ppm polyethyleneimine.

15. The method of claim 13 wherein the polymer comprises
about 60% acrylamide;
about 40% AMPS;
about 500 ppm polyethylene glycol diacrylate; and
about 400 ppm sodium formate;
wherein the crosslinker comprises about 200 ppm polyethyleneimine.

16. The method of claim 11 wherein the crosslinker comprises polyethyleneimine at a molecular weight of about 2,000-30,000 daltons.

17. The method of claim 16 wherein the polyethyleneimine has a molecular weight of about 10,000 daltons.

18. The method of claim 11 wherein the temperature stabilizer comprises about 0.02-0.1 wt % thiourea.

19. The method of claim 11 wherein the viscosity of the polymer system is about 1-10 cp before gelation.

20. The method of claim 11 wherein the polymer system undergoes gelation at a temperature between about 80-130 degrees Celsius and wherein the polymer gel is formed in a brine with total dissolved solids in the range of about 50,000 mg/L to 200,000 mg/L.

Assignees

• Cnpc Usa Corp
• Beijing Huamei Inc
• China Nat Petroleum Corp

Inventors

• Lu Meng
• Zhang Danhua
• Liu Fuchen
• Zhou Nancy
• Li Jianshen
• Zha Weibin

Classifications

• E21B43/16

  Enhanced recovery methods for obtaining hydrocarbons · CPC title

• C09K8/512 Primary

  containing cross-linking agents · CPC title

• C09K8/5083

  obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• C09K8/502

  Oil-based compositions · CPC title

• C09K8/588

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