Degradable polymer composition for use in downhole tools and method of manufacturing

Patent metadata

Field	Value
Publication number	US-11566097-B2
Application number	US-202016789946-A
Country	US
Kind code	B2
Filing date	Feb 13, 2020
Priority date	Feb 13, 2020
Publication date	Jan 31, 2023
Grant date	Jan 31, 2023

Abstract

A chemical composition for a degradable polymeric material includes an isocyanate terminated polyester prepolymer, including prepolymer units as a main chain with a plurality of isocyanates at ends of the main chain, and a cross-linking agent. The isocyanate terminated polyester prepolymer has a structural formula as follows:
ONC—R″—NH—[—CO—R—R′″-]n-NH—R″—CNO, wherein R′″ is selected from a group consisting of —O— and —CO—O—R′—O—,

wherein R, R′ and R″ are an aryl group or alkyl group and wherein n is a number of prepolymer units corresponding to length of the main chain. The composition degrades at a rate and at a delay depending on temperature and the composition for a component of a downhole tool. The composition has strength and elasticity for a component of a downhole tool.

First claim

We claim:

1. A chemical composition for a degradable polymeric material, the chemical composition comprising:
a reaction product of an isocyanate terminated polyester prepolymer, a cross-linking agent, wherein the isocyanate terminated prepolymer as a main chain with a plurality of isocyanates at ends of said main chain, said isocyanate terminated polyester prepolymer having a structural formula below:
ONC—R″—NH—[—CO—R—R′″-]n-NH—R″—CNO, wherein R′″ is selected from a group consisting of —O— and —CO—O—R′—O—,

wherein R is an aryl group,
wherein R′ is an aryl group,
wherein R″ is an aryl group, and
wherein n is a number of prepolymer units corresponding to length of said main chain, wherein said isocyanates are selected from group consisting of 2,4-toluene di-isocyanate, 2,6-toluene di-isocyanate, methylene diphenyl diisocyanate, para-phenyl diisocyanate (pPDI), wherein the cross-linking agent comprises at least one of dimethyl thio-toluene diamine; 4,4′ methylene-bis-(o-chloroaniline), and
wherein the reaction product reaches fracturing failure between 8 hours and 30 days in 0.3% KCl at 90° C., maintain less than 5% weight loss within 2 days and display more than 40% weight loss within 20 days in 0.3% KCl at 90° C., and maintain less than 5% hardness loss within 2 days in 0.3% KCl at 90° C.; and
a dissolution rate accelerating agent, wherein the dissolution rate accelerating agent comprises dibutyltin dilaurate.

2. The chemical composition of claim 1 ,
wherein the reaction product of said isocyanate terminated polyester prepolymer and said cross-linking agent reaches fracturing failure in 0.3% KCl at 90° C. within 15 days, in 1.0% KCl at 93° C. within 4 days, and in 0.3% KCl at 120° C. within 22 hours.

3. The chemical composition of claim 1 ,
wherein the reaction product of said isocyanate terminated polyester prepolymer and said cross-linking agent maintains less than 5% weight loss in 0.3% KCl at 90° C. within 2 days, and wherein said isocyanate terminated polyester prepolymer and said cross-linking agent display more than 40% weight change in 0.3% KCl at 90° C. within 20 days.

4. The chemical composition of claim 1 ,
wherein the reaction product of said isocyanate terminated polyester prepolymer and said cross-linking agent maintains less than 5% weight loss in 0.3% KCl at 90° C. within 2 days, and wherein said isocyanate terminated polyester prepolymer and said cross-linking agent delay more than 60% weight change in 0.3% KCl with said catalyst at 90° C. within 20 days.

5. The chemical composition of claim 4 ,
wherein the reaction product of said isocyanate terminated polyester prepolymer and said cross-linking agent maintain less than 5% hardness loss in 0.3% KCl at 90° C. within 2 days.

6. A chemical composition for a degradable polymeric material, the chemical composition comprising:
a reaction product of an isocyanate terminated polyester prepolymer, a cross-linking agent, wherein the isocyanate terminated prepolymer as a main chain with a plurality of isocyanates at ends of said main chain, said isocyanate terminated polyester prepolymer having a structural formula below:
ONC—R″—NH—[—CO—R—R′″-]n-NH—R″—CNO, wherein R′″ is selected from a group consisting of —O— and —CO—O—R′—O—,

wherein R is an aryl group,
wherein R′ is an aryl group,
wherein R″ is an aryl group, and
wherein n is a number of prepolymer units corresponding to length of said main chain, wherein said isocyanates are selected from group consisting of 2,4-toluene di-isocyanate, 2,6-toluene di-isocyanate, methylene diphenyl diisocyanate, para-phenyl diisocyanate (pPDI), wherein the cross-linking agent comprises at least one of dimethyl thio-toluene diamine, 4,4′ methylene-bis-(o-chloroaniline); and
wherein the reaction product has an average tensile strength over 5000 psi at room temperature with 84 Shore A, an average elongation break over 400% at room temperature with 84 Shore A, an average tensile strength less than 1300 psi with 84 Shore A at 90° C., an average elongation break over 300% at 90° C. with 84 Shore A, and a sealing element made of the material hold a 10000 psi differential over 24 hours; and
a dissolution rate accelerating agent, wherein the dissolution rate accelerating agent comprises dibutyltin dilaurate.

7. The chemical composition of claim 6 ,
wherein the reaction product of said isocyanate terminated polyester prepolymer and said cross-linking agent has an average tensile strength over 4500 psi with 84 Shore A at room temperature, an average tensile strength over 7000 psi with 93 Shore A at room temperature, an average elongation break over 500% with 84 Shore A at room temperature, and an average elongation break over 400% with 93 Shore A at room temperature.

8. The chemical composition of claim 6 ,
wherein the reaction product of said isocyanate terminated polyester prepolymer and said cross-linking agent has an average elongation break over 500% with 84 Shore A at 90° C. and an average elongation break over 300% with 93 Shore A at 90° C.

9. A method for formation of a degradable polymeric material, the method comprising the steps of:
vacuuming a prepolymer unit of claim 1 ;
vacuuming a cross-linking agent;
mixing said prepolymer unit and said cross-linking agent and said dissolution rate accelerating agent so as to form a mixture; and
molding said mixture so as to form a cured polymer as a component.

10. The method for formation, according to claim 9 ,
wherein the step of mixing said prepolymer unit, said cross-linking agent, and said dissolution rate accelerating agent is by centrifuge.

11. The method for formation, according to claim 9 ,
wherein the step of mixing said prepolymer unit, said cross-linking agent said dissolution rate accelerating agent is under vacuum.

12. The method for formation, according to claim 9 ,
wherein the step of mixing said prepolymer unit, said cross-linking agent said dissolution rate accelerating agent further comprises adding a filler.

13. The method for formation, according to claim 12 ,
wherein said filler is selected from a group consisting of carbon blacks, silica, nanographene, nanoclays, nanofibers, and nanotubes.

14. A method for removal, the method comprising the steps of:
forming a chemical composition according to claim 1 into a component;
installing said component in an assembly;
dissolving said component in a solution with salinity less than 0.3% at 90° C. into a degraded component; and
collapsing said assembly so as to remove said assembly and said degraded component.

15. The method for removal, according to claim 14 ,
wherein the step of dissolving said component further comprises a step of: adding a dissolution rate accelerating agent, and
wherein said dissolution rate accelerating agent is selected from a group consisting of: an acid and a base.

16. The method for removal, according to claim 15 , further comprising: dissolving said degraded component completely.

Assignees

• Cnpc Usa Corp
• Beijing Huamei Inc

Inventors

• Ren Jiaxiang
• Cheng Peng
• Wang Xu

Classifications

• C08G18/10 Primary

  Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step · CPC title

• C08G2230/00

  Compositions for preparing biodegradable polymers · CPC title

• E21B33/1208

  characterised by the construction of the sealing or packing means (E21B33/1277 takes precedence) · CPC title

• C08G18/73

  acyclic · CPC title

• C08G18/7628

  containing at least one isocyanate or isothiocyanate group linked to the aromatic ring by means of an aliphatic group · CPC title