Method and composition for sealing a subsurface formation

Patent metadata

Field	Value
Publication number	US-10954427-B2
Application number	US-201815982048-A
Country	US
Kind code	B2
Filing date	May 17, 2018
Priority date	May 17, 2018
Publication date	Mar 23, 2021
Grant date	Mar 23, 2021

Abstract

A method for plugging and sealing subsurface formations using alkaline nanosilica dispersion and a delayed activation chemistry is disclosed. In accordance with one embodiment of the present disclosure, the method includes introducing a mixture with a first pH into the subsurface formation. The mixture comprises an aqueous solution, an alkaline nanosilica dispersion and a water-soluble hydrolyzable compound. The method further includes allowing the water-soluble hydrolyzable compound to hydrolyze in the subsurface formation to form an acid at 70° C. or greater, thereby acidizing the mixture to a reduced second pH and causing the alkaline nanosilica dispersion to gel into a solid and seal the subsurface formation. A composition for sealing a subsurface formation is also disclosed. The composition includes an aqueous mixture including water, an alkaline nanosilica dispersion, and a water-soluble hydrolyzable compound.

First claim

What is claimed is:

1. A method of sealing a subsurface formation comprising:
introducing a mixture with a first pH into the subsurface formation in which the mixture comprises:
an aqueous solution,
a filtration control additive comprising at least one of starch and polyanionic cellulose,
sodium hydroxide,
an alkaline nanosilica dispersion, and
a water-soluble hydrolyzable organic salt selected from diethylene glycol diformate, ethylene glycol diacetate, and diethylene glycol dilactate; and

allowing the water-soluble hydrolyzable organic salt to hydrolyze in the subsurface formation to form an acid at 70° C. or greater, thereby acidizing the mixture to a reduced second pH and causing the alkaline nanosilica dispersion to gel into a solid and seal the subsurface formation.

2. The method of claim 1 , in which the mixture further comprises a viscosifier comprising at least one of bentonite and xanthan gum.

3. The method of claim 1 , in which the aqueous solution comprises at least one of fresh water, salt water, brine, municipal water, formation water, produced water, well water, filtered water, distilled water, sea water, or combinations of these.

4. The method of claim 1 , in which the aqueous solution comprises total dissolved solids of from 150,000 to 300,000 mg/L.

5. The method of claim 1 , in which causing the alkaline nanosilica dispersion to gel into a solid and seal the subsurface formation thereby reduces an amount of fluid breakthrough from the subsurface formation.

6. The method of claim 1 , in which the subsurface formation has a temperature of from 70 to 250° C.

7. The method of claim 6 , in which the temperature of the subsurface formation activates the water-soluble hydrolyzable organic salt.

8. The method of claim 1 , in which the first pH is greater than 7.

9. The method of claim 1 , in which the second pH is less than 7.

10. The method of claim 1 , in which the water-soluble hydrolyzable organic salt is diethylene glycol diformate and the acid is formic acid.

11. The method of claim 1 , in which a gelation time of the mixture in the subsurface formation ranges from 2 minutes to 5 hours.

12. The method of claim 1 , in which the subsurface formation comprises carbonate or sandstone.

13. The method of claim 1 , in which a viscosity of the mixture is 5 cP or less when introducing the mixture into the subsurface formation.

14. The method of claim 1 , in which the alkaline nanosilica dispersion is from 30 to 60 wt. % silicon dioxide.

15. The method of claim 1 , in which the weight ratio of the alkaline nanosilica dispersion to the water-soluble hydrolyzable organic salt is from 50:1 to 80:1.

16. The method of claim 1 , in which the water-soluble hydrolyzable organic salt is selected from diethylene glycol diformate and diethylene glycol dilactate.

Assignees

• Saudi Arabian Oil Co

Inventors

• Kalgaonkar Rajendra Arunkumar
• Wagle Vikrant

Classifications

• C04B28/24

  containing alkyl, ammonium or metal silicates; containing silica sols {(reaction mixtures resulting in mineral polymers C04B28/006; polymeric reaction products of alkali metal silicates with isocyanates C08G18/3895)} · CPC title

• C09K8/506 Primary

  containing organic compounds · CPC title

• C09K8/487

  Fluid loss control additives; Additives for reducing or preventing circulation loss · CPC title

• C09K2208/10

  Nanoparticle-containing well treatment fluids · CPC title

• C09K8/467 Primary

  containing additives for specific purposes · CPC title