Method for a fracturing fluid system at high temperatures

Patent metadata

Field	Value
Publication number	US-10066151-B2
Application number	US-201815948766-A
Country	US
Kind code	B2
Filing date	Apr 9, 2018
Priority date	Nov 18, 2015
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

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. The ascorbic acid stabilizes viscosity of the gelling agent, adjusts pH, and delays cross linking. Amount of components and additional components, such as a cross-linking agent, a breaker, another adjusting agent and an inverting surfactant adjust the fracturing fluid system for well conditions and a type of treatment to be completed.

First claim

The invention claimed is:

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

fracturing said rock formation at a temperature between 150-260 degrees Celsius;
adjusting pH of said fracturing fluid system with said ascorbic acid, said fracturing fluid system having a pH ranging from about 3.5 to 6.9 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 so as to increase viscosity of said fracturing fluid system;
delaying said cross linking of said gelling, agent with said ascorbic acid; and
recovering said fluid components of said fracturing fluid system from said wellbore, wherein the ascorbic acid is present as a fluid component of the fracturing fluid in a range of from about 1 ppt to about 50 ppt so as to adjust pH and delay cross linking of said gelling 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 said fracturing fluid system further comprises an inverting surfactant to hydrate the polymer in said water, the polymer being an emulsion polymer.

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 cross linking agent is selected from at least one of a group consisting of boron based compounds, zirconium based compounds, and titanium based compounds.

7. The method for well-stimulation, according to claim 1 , wherein said fracturing fluid system further comprises a breaker, and wherein the step of recovering said fluid components comprises loading said breaker into said fracturing fluid system, after the step of fracturing.

8. The method for well-stimulation, according to claim 1 , wherein the step of injecting 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.

9. The method for well-simulation, according to claim 1 , wherein said ascorbic acid ranges from about 3 ppt to about 25 ppt so as to adjust pH and delay said cross linking agent.

10. The method for well-stimulation, according to claim 9 , wherein said pH adjusting agent maintains said fracturing fluid system in a range of about 3.5 to about 6.9 as a linear gel.

11. A method for well-stimulation through a wellbore in a rock formation, comprising the steps of:
injecting a fracturing fluid system to said rock formation, said fracturing fluid system comprising:
a proppant; and a plurality of fluid components, said fluid components being comprised of:
water;
a gelling agent;
a cross linking agent; and
a stabilizer comprising ascorbic acid;

adjusting pH of said fracturing fluid system with ascorbic acid, said fracturing fluid system having a pH in a range of from about 3.5 to about 6.9 as a linear gel before adding said cross linking agent to said fracturing fluid system;
fracturing, said rock formation at a temperature between 150-260 degrees Celsius;
cross linking said gelling agent with said cross linking agent so as to increase viscosity of said fracturing fluid system without a spike in apparent viscosity;
delaying said cross linking of said gelling agent with said ascorbic acid; and
recovering said fluid components of said fracturing fluid system from said wellbore, wherein the ascorbic acid is present as a fluid component of the fracturing fluid in a range of from about 1 ppt to about 50 ppt so as to adjust pH and delay cross linking of said gelling agent.

Assignees

• Cnpc Usa Corp

Inventors

• Song Lulu
• Yang Zhenzhou

Classifications

• C09K8/887

  containing cross-linking agents · CPC title

• C09K8/685 Primary

  containing cross-linking agents · CPC title

• E21B43/267

  reinforcing fractures by propping · CPC title

• C08F220/56

  Acrylamide; Methacrylamide · CPC title

• C09K8/885

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