pH-sensitive temporary plugging agent, preparation method thereof, and use thereof in exploitation of low-permeability oil reservoir

Patent metadata

Field	Value
Publication number	US-11891563-B2
Application number	US-202117469669-A
Country	US
Kind code	B2
Filing date	Sep 8, 2021
Priority date	Apr 15, 2021
Publication date	Feb 6, 2024
Grant date	Feb 6, 2024

Abstract

A pH-sensitive temporary plugging agent and its preparation method, and the use thereof in exploitation of a low-permeability oil reservoir are disclosed. The temporary plugging agent is prepared by raw materials including, in percentages by mass, 3-8% of carboxymethyl chitosan, 0.2-0.7% of gelatin, 0.1-0.6% of an initiator, 5-15% of a toughener, and a balance of water, wherein the initiator is a solution of AgNO3 in ammonia water having a concentration of 0.1-0.3 mol/L, and the toughener is a carboxyl-terminated hyperbranched polyester.

First claim

What is claimed is:

1. A method for preparing a pH-sensitive temporary plugging agent, comprising:
mixing raw materials to obtain a final mixed solution, the raw materials comprising, in percentages by mass,
3-8% of carboxymethyl chitosan,
0.2-0.7% of gelatin,
0.1-0.6% of an initiator,
5-15% of a toughener, and
a balance of water,
wherein the initiator is a solution of AgNO 3 in ammonia water having a concentration of 0.1-0.3 mol/L, and
the toughener is a carboxyl-terminated hyperbranched polyester; and

subjecting the final mixed solution to a crosslinking reaction at 40-60° C. to obtain the pH-sensitive temporary plugging agent.

2. The method as claimed in claim 1 , wherein the mixing raw materials comprises:
mixing carboxymethyl chitosan, gelatin with one part of water at 50-70° C. to obtain a first mixed solution;
adding the initiator dropwise into the first mixed solution to obtain a second mixed solution;
mixing the toughener with the other part of water to obtain an aqueous solution of the toughener; and
mixing the second mixed solution with the aqueous solution of the toughener to obtain the final mixed solution.

3. The method as claimed in claim 2 , wherein a mass ratio of the one part of water to the other part of water is in the range of (1-2): 1.

4. The method as claimed in claim 1 , wherein the crosslinking reaction is performed for 0.5-2 hours.

5. The method as claimed in claim 1 , further comprising, after the crosslinking reaction, lyophilizing the resulting crosslinked product.

6. The method as claimed in claim 1 , wherein the raw materials comprises, in percentages by mass,
3.5-7% of carboxymethyl chitosan,
0.3-0.6% of gelatin,
0.2-0.5% of the initiator,
6.5-14.5% of the toughener, and
the balance of water.

7. The method as claimed in claim 4 , further comprising, after the crosslinking reaction, lyophilizing the resulting crosslinked product.

Assignees

• Univ Yangtze

Inventors

• Yang Huan
• Jiang Zhuyang
• Yu Xiaorong
• Su Gaoshen
• Wang Kailu
• Zhang Beibei
• Li Yang
• Xiao Chang

Classifications

• C09K8/426 Primary

  for plugging · CPC title

• C09K8/035 Primary

  Organic additives · CPC title

• C09K8/44

  containing organic binders only · CPC title

• C09K8/514 Primary

  of natural origin, e.g. polysaccharides, cellulose (C09K8/512 takes precedence) · CPC title

• C09K8/5086

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