Low Concentration Synthetic Polymer Fracturing Fluid with Ascorbic Acid

Patent metadata

Field	Value
Publication number	US-2024368460-A1
Application number	US-202318143840-A
Country	US
Kind code	A1
Filing date	May 5, 2023
Priority date	May 5, 2023
Publication date	Nov 7, 2024
Grant date	—

Abstract

A fracturing fluid for fracturing subterranean formations comprising ascorbic acid. The fracturing fluid can use ascorbic acid to delay increases in viscosity until desired. The viscosity increase can then be maintained over a period of time to perform fracturing operations.

First claim

1 . A method for well-stimulation through a wellbore in a rock formation, comprising the steps of:
preparing a fracturing fluid system, the fracturing fluid system comprising: a proppant, water, a gelling agent, a stabilizer comprising ascorbic acid, a cross linking agent, and a pH adjuster; cross-linking the gelling agent with the cross-linking agent; delaying cross-linking of the gelling agent with the cross-linking agent using the ascorbic acid; adjusting a pH of the fracturing fluid system with the pH adjuster to about 5.5 to 6.5; pumping the fracturing fluid system to the rock formation, wherein the fracturing fluid system is capable of maintaining a viscosity above about 100 centipoise (cP) for at least 90 minutes; fracturing the rock formation at a temperature between about 100 to 149 degrees Celsius; and recovering the fluid components of the fracturing fluid system from the wellbore; wherein the ascorbic acid ranges from about 0.5 to 2 parts per thousand (ppt).

2 . The method of claim 1 , wherein the proppant is comprised of a granular material to prevent fractures from closing.

3 . The method of claim 1 , wherein the gelling agent is comprised of a synthetic polymer resistant to hydrolysis.

4 . The method of claim 3 , wherein the fracturing fluid system further comprises an inverting surfactant to invert an emulsion polymer for the hydration of the emulsion polymer in the water, wherein the synthetic polymer is the emulsion polymer.

5 . The method of claim 1 , wherein the gelling agent is comprised of a copolymer derived from acrylamide, 2-Acrylamido-2-methylpropane sulfonic acid (AMPS), and vinyl phosphonate.

6 . The method of claim 3 , further comprising:
cross-linking the synthetic polymer with metal ions of the cross-linking agent so as to increase a viscosity of the fracturing fluid system.

7 . The method of claim 1 , wherein the cross-linking agent is a zirconium-based compound or a titanium-based compound.

8 . The method of claim 1 , wherein the fracturing fluid system further comprises a breaker to reduce the viscosity of the fracturing fluid system after the fracturing is complete.

9 . The method of claim 1 , further comprising:
forming the ascorbic acid in the fracturing fluid system by loading an ascorbate salt and an acid into the fracturing fluid system.

10 . The method of claim 1 , further comprising:
adding the cross-linking agent to the fracturing fluid system; and cross linking the gelling agent at a pre-set depth, after the step of delaying cross linking with the ascorbic acid.

11 . The method of claim 1 , further comprising:
delaying cross linking for an amount of time by adjusting an amount of ascorbic acid in the fracturing fluid system.

12 . The method of claim 8 , further comprising:
controlling timing and depth of release the breaker in order to break the fracturing fluid system.

13 . The method of claim 12 , wherein the breaker is encapsulated for controlling the timing and depth of release of the breaker into the fracturing fluid system.

14 . The method of claim 8 , wherein the breaker is comprised of an oxidizing breaker.

15 . The method of claim 14 , wherein the oxidizing breaker is sodium bromate, ammonium persulfate, or peroxide.

16 . The method of claim 1 , wherein the fracturing fluid system further comprises a buffer.

17 . The method of claim 16 , wherein the buffer is sodium bicarbonate or formic acid.

18 . The method of claim 1 , wherein the fracturing fluid system does not comprise sodium thiosulfate.

19 . The method of claim 14 wherein the oxidizing breaker is encapsulated ammonium persulfate.

20 . The method of claim 1 wherein the fracturing fluid system further comprises clay stabilizers, nonemulsifiers, surfactants aiding flowback, scale inhibitors, or biocides.

Assignees

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

Inventors

• Song Lulu
• Yu Stephanie

Classifications

• C09K8/68

  containing organic compounds · CPC title

• E21B43/26

  by forming crevices or fractures · CPC title

• C09K8/70

  characterised by their form or by the form of their components, e.g. foams · CPC title

• C09K8/80

  Compositions for reinforcing fractures, e.g. compositions of proppants used to keep the fractures open · CPC title

• C09K8/685 Primary

  containing cross-linking agents · CPC title