Dual-mechanism thickening agents for hydraulic fracturing fluids

• US 10,654,960 B2
• Filed: 09/06/2017
• Issued: 05/19/2020
• Est. Priority Date: 08/30/2012
• Status: Active Grant

• Current Assignee: Pilot Polymer Technologies Incorporated
• Original Assignee: Pilot Polymer Technologies Incorporated
• Inventors: McCarthy, Patrick, Liao, Yuanxi, Huang, Liang
• Primary Examiner(s): Li, Aiqun
• Application Number:
  US15/697,179
• Publication Number:
  US 20180127531A1
• Time in Patent Office: 986 Days
• CPC Class Codes: C08F 220/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• CPC Class Codes: C08F 2438/01 Atom Transfer Radical Polymerization [ATRP] or reverse ATRP
• CPC Class Codes: C08F 293/005 using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent
• CPC Class Codes: C09K 8/035 Organic additives
• CPC Class Codes: C09K 8/64 Oil-based compositions
• CPC Class Codes: C09K 8/685 containing cross-linking agents
• CPC Class Codes: C09K 8/70 characterised by their form or by the form of their components, e.g. foams
• CPC Class Codes: C09K 8/88 macromolecular compounds
• CPC Class Codes: C09K 8/887 containing cross-linking agents
• CPC Class Codes: C09K 8/92 characterised by their form or by the form of their components, e.g. encapsulated material C09K8/70 takes precedence

Abstract

The present invention relates to multi-arm star macromolecules which are used as thickening agents or rheology modifiers, including use in hydraulic fracturing fluid compositions. In one aspect of the invention, a star macromolecule is capable of thickening via a dual mechanism comprising (1) self-assembly of the hydrophobic polymerized segments of the star macromolecules via hydrophobic interactions or associations, and (2) association, reaction, or combination of the hydroxyl-containing polymerized segments of one or more of the star macromolecules.

Claims

1. A dual-mechanism thickening agent comprising a gel-forming star macromolecule, wherein the gel-forming star macromolecule is represented by Formula (I):

2. The dual-mechanism thickening agent of claim 1, wherein the gel-forming star macromolecule has a molecular weight of between 150,000 g/mol and 5,000,000 g/mol, the gel-forming star macromolecule forming a homogeneous gel when dissolved in water at a concentration of at least 0.05 wt. %, wherein the gel has:

i) a dynamic viscosity of at least 20,000 cP;

ii) a shear-thinning value of at least 10;

iii) an increase in dynamic viscosity of at least 5,000 cP in a 0.2 wt. % Borax aqueous solution, according to Borate-Crosslinker Thickening Test;

or

iv) combinations thereof.

3. The dual-mechanism thickening agent of claim 1, wherein the gel-forming star macromolecule has an increase in dynamic viscosity in the range of between 5,000 cP to 30,000 cP, or an increase in dynamic viscosity of at least 12%, in a 0.2 wt. % Borax aqueous solution, according to the Borate-Crosslinker Thickening Test, relative to the dynamic viscosity of a homogeneous gel of the star macromolecule with 0.0 wt. % Borax aqueous solution.

4. The dual-mechanism thickening agent of claim 1, wherein the gel-forming star macromolecule has a viscosity of less than 5,000 cP at a shear rate of 4 sec⁻

1.

5. The dual-mechanism thickening agent of claim 1, wherein the gel-forming star macromolecule has a PDI in the range of between 1.0 to 8.0.

6. The dual-mechanism thickening agent of claim 1, wherein the gel-forming star macromolecule has a pH-induced break value of at least 50%.

7. The dual-mechanism thickening agent of claim 1, wherein the gel-forming star macromolecule has an emulsion value of >

12 hours.

8. The dual-mechanism thickening agent of claim 1, wherein the gel-forming star macromolecule is a water-soluble mikto star macromolecule.

9. The dual-mechanism thickening agent of claim 1, wherein the core comprises a hydrophobic crosslinked polymeric segment.

10. The dual-mechanism thickening agent of claim 1, wherein the sum total number of arms (r+t) is between 3 and 1000, or the sum total number of arms (s+t) is between 3 and 1000, or both sum total number of arms (r+t) and sum total number of arms (s+t) are each between 3 and 1000.

11. The dual-mechanism thickening agent of claim 1, wherein the molar ratio of r tot is in the range of between 8:

1 and 3;

1, or the molar ratio of s tot is in the range of between 8;

1 and 3;

1, or both the molar ratio of r to t and the molar ratio of s to t are each in the range of between 8;

1 and 3;

1.

12. The dual-mechanism thickening agent of claim 1, wherein:

i) both q2 and q3 have a value greater than 100, and q2 is greater than q3;

or

ii) both q5 and q3 have a value greater than 100, and q5 is greater than q3;

or

iii) both q2 and q3 have a value greater than 100, and q5 and q3 have a value greater than 100, and q2 and q5 are greater than q3.

13. The dual-mechanism thickening agent of claim 1, wherein

i) the molar ratio of r to s is in the range of between 40:

1 and 1;

40;

ii) the molar ratio of r to t is in the range of between 40;

1 and 1;

40;

iii) the molar ratio oft to s is in the range of between 40;

1 and 1;

40;

or

iv) combinations thereof.

14. A composition, comprising the dual-mechanism thickening agent of claim 1.

15. The composition of claim 14, wherein the composition comprises at least 0.05 wt. % of the gel-forming star macromolecule.

16. The composition of claim 14, wherein the composition is a fracturing fluid thickening additive, a drilling well fluid thickening additive, a gelling agent, or an additive to improve oil extraction from oil sands.

17. The composition of claim 14, wherein the composition is a rheology-modifying composition having a shear-thinning value of at least 6.

18. The composition of claim 14, wherein the composition further comprises one or more boric acid additives or borate-type additives.

19. The composition of claim 14, wherein the gel-forming star macromolecule is prepared by one or more star macromolecule processes, comprising:

one-pot process, the arm first process, ATRP, CRP, RAFT, TEMPO, Nitroxide, LRP, anionic polymerization, cationic polymerization, or combinations thereof.