Encapsulated agent, method of manufacturing encapsulated agent, and variable viscosity fluid

Patent metadata

Field	Value
Publication number	US-10774259-B2
Application number	US-201615745968-A
Country	US
Kind code	B2
Filing date	Jul 29, 2016
Priority date	Jul 31, 2015
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

An encapsulated agent includes a central part and an outer part that covers a surface of the central part. The central part contains a viscosity-reducing material that reduces viscosity of a fluid to be used in a hydrofracturing technique. The outer part contains a plurality of particulate substances and a holding material that holds the plurality of particulate substances and enables gradual release of the central part in the fluid. The outer part involves distribution of the plurality of particulate substances that allows a content to have one or more local maxima in a direction away from the central part.

First claim

The invention claimed is:

1. An encapsulated agent comprising:
a central part containing a viscosity-reducing material that reduces viscosity of a fluid to be used in a hydrofracturing technique; and
an outer part that (1) covers a surface of the central part, (2) contains a plurality of particulate substances and a holding material, and (3) involves distribution of the plurality of particulate substances that allows a content to have one or more local maxima in a direction away from the central part, the holding material holding the plurality of particulate substances and enabling gradual release of the central part in the fluid,
wherein the outer part includes a large-content region and a small-content region, the content of the plurality of particulate substances in the large-content region is larger than the content of the plurality of particulate substances in the small-content region, and
the large-content region and the small-content region are disposed alternately in the direction away from the central part.

2. The encapsulated agent according to claim 1 , wherein the large-content region includes the plurality of particulate substances, and
the small-content region does not include the plurality of particulate substances.

3. The encapsulated agent according to claim 1 , wherein the small-content region is disposed at a position closest to the central part.

4. The encapsulated agent according to claim 1 , wherein the small-content region is disposed at a position farthest from the central part.

5. The encapsulated agent according to claim 1 , wherein the fluid contains a viscosity-thickening agent, and
the viscosity-reducing agent contains a material that decomposes the viscosity-thickening agent.

6. A variable viscosity fluid comprising:
a fluid body; and
one or more encapsulated agents including a central part and an outer part, the central part containing a viscosity-reducing material that reduces viscosity, the outer part (1) covering a surface of the central part, (2) containing a plurality of first particulate substances and a holding material, and (3) involving distribution of the plurality of first particulate substances that allows a content to have one or more local maxima in a direction away from the central part, the holding material holding the plurality of first particulate substances and enabling gradual release of the central part,
wherein the outer part includes a large-content region and a small-content region, the content of the plurality of first particulate substances in the large-content region is larger than the content of the plurality of first particulate substances in the small-content region, and
the large-content region and the small-content region are disposed alternately in the direction away from the central part.

7. The variable viscosity fluid according to claim 6 , further comprising a plurality of second particulate substances that are not held by the holding material.

8. The variable viscosity fluid according to claim 6 , further comprising a viscosity-thickening agent, wherein the viscosity-reducing agent contains a material that decomposes the viscosity-thickening agent.

9. The variable viscosity fluid according to claim 6 , wherein the variable viscosity fluid is to be used in a hydrofracturing technique.

10. A method of manufacturing an encapsulated agent, the method comprising:
preparing a coating solution containing a holding material; and
forming an outer part that (1) covers a surface of a central part, (2) contains a plurality of particulate substances and the holding material, and (3) involves distribution of the plurality of particulate substances that allows a content to have one or more local maxima in a direction away from the central part, the central part containing a viscosity-reducing material that reduces viscosity of a fluid to be used in a hydrofracturing technique, the holding material holding the plurality of particulate substances and enabling gradual release of the central part in the fluid,
by supplying the plurality of particulate substances to the surface of the central part to thereby repeatedly increase and decrease an amount of the plurality of particulate substances to be supplied to the surface of the central part, while applying the coating solution to the surface of the central part,
wherein the outer part includes a large-content region and a small-content region, the content of the plurality of particulate substances in the large-content region is larger than the content of the plurality of particulate substances in the small-content region, and
the large-content region and the small-content region are disposed alternately in the direction away from the central part.

11. The method according to claim 10 , wherein the plurality of particulate substances are supplied intermittently.

12. A method of manufacturing an encapsulated agent, the method comprising:
preparing a first coating solution and a second coating solution, the first coating solution containing a holding material and having a concentration of a plurality of particulate substances that is a first concentration, the second coating solution containing the holding material and having a concentration of the plurality of particulate substances that is a second concentration, the second concentration being higher than the first concentration; and
forming an outer part that (1) covers a surface of a central part, (2) contains the plurality of particulate substances and the holding material, and (3) involves distribution of the plurality of particulate substances that allows a content to have one or more local maxima in a direction away from the central part, the central part containing a viscosity-reducing material that reduces viscosity of a fluid to be used in a hydrofracturing technique, the holding material holding the plurality of particulate substances and enabling gradual release of the central part in the fluid,
by alternately applying, onto the surface of the central part, the first coating solution and the second coating solution one or more times,
wherein the outer part includes a large-content region and a small-content region, the content of the plurality of particulate substances in the large-content region is larger than the content of the plurality of particulate substances in the small-content region, and
the large-content region and the small-content region are disposed alternately in the direction away from the central part.

13. The method according to claim 12 , wherein the second coating solution contains the plurality of particulate substances, and
the first coating solution does not contain the plurality of particulate substances.

14. A method of manufacturing an encapsulated agent, the method comprising:
preparing a coating solution containing a holding material; and
forming an outer part that (1) covers a surface of a central part, (2) contains a plurality of particulate substances and the holding material, and (3) involves distribution of the plurality of particulate substances that allows a content to have one or more local maxima in a direction away from the central part, the central part containing a viscosity-reducing material that reduces viscosity of a fluid to be used in a hydrofracturing technique, the holding material holding the plurality of particulate substances and enabling gradual release of the central part in the fluid,
by alternately repeating, on the surface of the central part, a process of applying the coating solution and a process of attaching the plurality of particulate substances to the applied coating solution,
wherein the outer p

Assignees

• Adeka Corp

Inventors

• Homma Masatoshi
• Noda Kazuyuki
• Shinano Hirokatsu
• Akimoto Kensaku
• Sawamoto Daisuke

Classifications

• E21B43/267

  reinforcing fractures by propping · CPC title

• B01J13/043

  Drying and spraying · CPC title

• C09K8/706 Primary

  Encapsulated breakers · CPC title

• C09K8/92

  characterised by their form or by the form of their components, e.g. encapsulated material (C09K8/70 takes precedence) · CPC title

• C09K8/80

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