Method for a fracturing fluid system at high temperatures

Patent metadata

Field	Value
Publication number	US-10815419-B2
Application number	US-201916659192-A
Country	US
Kind code	B2
Filing date	Oct 21, 2019
Priority date	Nov 18, 2015
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

The method for well-stimulation through a wellbore in a rock formation is hydraulic fracturing under high temperature conditions. The method includes injecting a fracturing fluid system to the rock formation; fracturing the rock formation at a temperature between 150-260 degrees Celsius; and recovering fluid components of the fracturing fluid system from the wellbore and setting the proppant in the fractures. The fracturing fluid system includes proppant and a plurality of fluid components. The fluid components can include water, a gelling agent, and a stabilizer made of ascorbic acid ranging from 50-100 ppt so as to adjust pH and delay said cross linking agent.

First claim

The invention claimed is:

1. A method for well-stimulation through a wellbore in a rock formation, comprising the steps of:
preparing a fracturing fluid system, said fracturing fluid system comprising:
a proppant;
a plurality of fluid components, said fluid components being comprised of:
water;
a gelling agent;
a stabilizer comprising ascorbic acid;
a cross linking agent;
buffers including sodium bicarbonate or formic acid and

adjusting pH of said fracturing fluid system with said ascorbic acid, said fracturing fluid system having a pH ranging from about 3.1 to 3.5 as a linear gel before adding said cross linking agent to said fracturing fluid system;
cross linking said gelling agent with said cross linking agent;
delaying cross linking of said gelling agent with said cross linking agent using said ascorbic acid;
pumping the fracturing fluid system to said rock formation;
fracturing said rock formation at a temperature between 150-260 degrees Celsius; and
recovering said fluid components of said fracturing fluid system from said wellbore;
wherein said ascorbic acid ranges from 50-100 ppt so as to adjust pH and delay said cross linking agent.

2. The method for well-stimulation, according to claim 1 , wherein said proppant is comprised of a granular material to prevent fractures from closing.

3. The method for well-stimulation, according to claim 1 , wherein said gelling agent is comprised of a high molecular weight synthetic polymer resistant to hydrolysis.

4. The method for well-stimulation, according to claim 3 , wherein the step of cross linking said gelling agent comprises the step of: cross linking the polymer with metal ions with said cross linking agent so as to increase viscosity of said fracturing fluid system.

5. The method for well-stimulation, according to claim 1 , wherein said gelling agent is comprised of a copolymer derived from acrylamide, acrylamidomethylpropanesulfonic acid, and vinyl phosphonate.

6. The method for well-stimulation, according to claim 1 , wherein said fracturing fluid system further comprises a breaker.

7. The method for well-stimulation, according to claim 6 , further comprises controlling timing and depth of release the breaker in order to break the fracturing fluid system.

8. The method for well-stimulation, according to claim 7 , wherein said breaker is encapsulated for controlling the timing and depth of release of said breaker into the fracturing fluid system.

9. The method for well-stimulation, according to claim 6 , wherein said breaker is comprised of an oxidizing breaker.

10. The method for well-stimulation, according to claim 6 , wherein said oxidizing breaker is sodium bromate or peroxide.

11. The method for well-stimulation, according to claim 1 , wherein said cross linking agent is selected from at least one of a group consisting of boron based compounds, zirconium based compounds, and titanium based compounds; wherein the cross linking agent further comprises sodium thiosulfate or methanol as a stabilizer.

12. The method for well-stimulation, according to claim 1 , wherein said fracturing fluid system further comprises an inverting surfactant to hydrate the polymer in said water, the polymer being an emulsion polymer.

13. The method for well-stimulation, according to claim 1 , wherein the step of preparing said fracturing fluid system comprises: forming said ascorbic acid in said fracturing fluid system by loading an ascorbate salt and an acid into said fracturing fluid system.

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

15. The method for well-stimulation, according to claim 1 , wherein the step of delaying cross linking comprises: delaying cross linking for an amount of time by adjusting an amount of ascorbic acid in said fracturing fluid system so as to control said amount of time.

Assignees

• Cnpc Usa Corp

Inventors

• Song Lulu
• Yang Zhenzhou

Classifications

• C09K8/685 Primary

  containing cross-linking agents · CPC title

• E21B43/267

  reinforcing fractures by propping · CPC title

• C09K8/885

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

• C09K2208/26

  Gel breakers other than bacteria or enzymes · CPC title

• C09K8/887

  containing cross-linking agents · CPC title