Expandable plugging agent and preparation method thereof, micro-capsule plugging agent, water-based drilling fluid, and use thereof

Patent metadata

Field	Value
Publication number	US-10487255-B1
Application number	US-201916285783-A
Country	US
Kind code	B1
Filing date	Feb 26, 2019
Priority date	Jan 14, 2019
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

An expandable plugging agent is described. The expandable plugging agent is obtained through a polymerization reaction of acrylamide, a strength improving material, an acrylate, and gelatinized colloid, the acrylate is obtained through a neutralization reaction of an acidity neutralizer and acrylic acid, and the gelatinized colloid is obtained through a gelatinization reaction of starch in deionized water.

First claim

What is claimed is:

1. An expandable plugging agent for drilling fluid, which is viscoelastic gel obtained through a polymerization reaction of first acrylic acid, acrylamide, acrylate, a strength improving material, and gelatinized colloid in the presence of a cross-linking agent and an initiating agent, wherein the acrylate is obtained through a neutralization reaction of an acidity neutralizer and second acrylic acid, and the gelatinized colloid is obtained through a gelatinization reaction of starch in deionized water,
wherein the first acrylic acid and the second acrylic acid are acrylic acid, the first acrylic acid participates in reaction with acrylamide, and the second acrylic acid participates in the neutralization reaction,
wherein based on 100 parts by weight deionized water, the first acrylic acid and the acrylamide are in 1-15 parts by weight total amount, the starch is in 1-10 parts by weight, the acidity neutralizer is in 0.5-5 parts by weight, the cross-linking agent is in 0.1-0.8 parts by weight, the initiating agent is in 1-9 parts by weight, and the strength improving material is in 20-70 parts by weight.

2. The expandable plugging agent according to claim 1 , wherein the cross-linking agent is one or more of N,N-methylene-bis acrylamide, N-methylol acrylamide, and diacetone acrylamide.

3. The expandable plugging agent according to claim 1 , wherein the strength improving material is calcium carbonate and/or walnut shell.

4. The expandable plugging agent according claim 1 , wherein the water absorption multiple of the expandable plugging agent is 150-180, the relative molecular weight is 5×10 5 to 8×10 5 , the elastic modulus is 9×10 4 to 12×10 4 Pa, and the tensile strength is 4,500-5,000N/cm 2 .

5. A method for preparing the expandable plugging agent according to claim 1 , comprising:
(1) adding starch into deionized water to have the gelatinization reaction to obtain gelatinized colloid;
(2) adding the acidity neutralizer and acrylic acid to have the neutralization reaction to obtain the acrylate;
(3) controlling first acrylic acid, acrylamide, the acrylate, the strength improving material, and the gelatinized colloid to have the polymerization reaction in the presence of the cross-linking agent and the initiating agent.

6. The method according to claim 5 , wherein in the step (3), the conditions of the polymerization reaction include: 40-60° C. reaction temperature and 6-7 h reaction time.

7. A micro-capsule plugging agent for drilling fluid, comprising an intra-capsular material and a capsular enclosure material that encloses the intra-capsular material, wherein the intra-capsular material is
the expandable plugging agent according to claim 1 and
the capsular enclosure material is one or more of paraffin, stearic acid, bee wax, Japan wax, long-chain alcohol, polyethylene with number-average molecular weight lower than 5,000 g/mol, solidified oil, and deformable resin.

8. The expandable plugging agent according to claim 1 , wherein the mass ratio of the first acrylic acid to acrylamide is (0.4-0.8):1.

9. The expandable plugging agent according to claim 8 , wherein the acidity neutralizer is sodium hydroxide and/or calcium oxide.

10. The expandable plugging agent according to claim 2 , wherein the initiating agent is a mixture of ammonium persulfate and sodium sulfite.

11. The expandable plugging agent according to claim 10 , wherein the mass ratio of the ammonium persulfate to the sodium sulfite is (0.4-0.8):1.

12. The expandable plugging agent according to claim 3 , wherein the calcium carbonate comprises calcium carbonate A and calcium carbonate B, the average particle diameter of the calcium carbonate A is 8-12 μm, and the average particle diameter of the calcium carbonate B is 4-6 μm.

13. The expandable plugging agent according to claim 12 , wherein the average particle diameter of the walnut shell is 18-22 μm.

14. The expandable plugging agent according to claim 13 , wherein the mass ratio of the calcium carbonate A to the calcium carbonate B to the walnut shell is (0.4-0.6):(0.4-0.6):1.

15. The micro-capsule plugging agent for drilling fluid according to claim 7 , wherein the capsular enclosure material is paraffin.

16. The micro-capsule plugging agent for drilling fluid according to claim 15 , wherein the weight ratio of the capsular enclosure material to the intra-capsular material is (2-5):1.

Assignees

• Univ Southwest Petroleum

Inventors

• Bai Yang
• Luo Pingya
• Sun Jinsheng
• Jiang Guancheng
• Deng Jiading
• Cheng Yan
• Li Guojun

Classifications

• C09K8/44 Primary

  containing organic binders only · CPC title

• C09K8/426 Primary

  for plugging · CPC title

• C04B26/06

  Acrylates · CPC title

• C04B20/1025

  Fats; Fatty oils; Ester type waxes; Higher fatty acids; Derivatives thereof · CPC title

• C09K2208/30

  Viscoelastic surfactants [VES] · CPC title