Disintegrating agglomerated sand frack plug

Patent metadata

Field	Value
Publication number	US-10018010-B2
Application number	US-201414163732-A
Country	US
Kind code	B2
Filing date	Jan 24, 2014
Priority date	Jan 24, 2014
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

The frack plug has a sealing element that reforms when set to hold differential pressure. The element is granular with adhesive to hold the granular particles together but allow the shape to reform under setting force. The adhesive can be broken down with a chemical agent or in other ways to allow the seal to reform to the sealing position at the desired depth. As a result the structural components can disintegrate and the seal assembly can fragment into small pieces that can be circulated out of the well or allowed to drop to the hole bottom. The seal can have particles of controlled electrolytic materials (CEM), natural or synthetic sand, swelling or non-swelling rubber. The assembly can contain pellets that selectively release to initiate the breakdown of the structural components of the frack plug.

First claim

We claim:

1. A removable plug for subterranean use, comprising:
a mandrel made of a mandrel material that can be structurally compromised after a predetermined time with exposure to existing well conditions upon running in or later created well conditions;
a sealing element comprising at least one granular material external to and in direct contact with said mandrel for a run in and a set position created by an actuation assembly in direct contact with said at least one granular material that defines the shape of said sealing element said actuation assembly remaining clear of a borehole wall while selectively axially crushing said sealing element against the borehole wall or crushing said sealing element axially while forcing said at least one granular material radially along a ramp to contact a surrounding borehole wall for resisting applied differential pressure in said set position;
whereupon setting said sealing element in said set position and application of said differential pressure, exposure of said mandrel to existing or subsequent well conditions causes said structural compromise of said mandrel to allow said granular sealing element material to disperse so that the plug is removed from a subterranean location.

2. The plug of claim 1 , wherein:
said sealing element granular material is retained with a binder.

3. The plug of claim 2 , wherein:
said binder is compromised when said sealing element is in said set position.

4. The plug of claim 2 , wherein:
said binder is compromised with a substance released from within said sealing element.

5. The plug of claim 4 , wherein:
said sealing element contains an encapsulated chemical that is released when said sealing element is axially compressed to said set position.

6. The plug of claim 1 , wherein:
said sealing element granular material is formed into multiple initial unit shapes defining gaps;
said unit shapes are broken when said sealing element is in said set position.

7. The plug of claim 6 , wherein:
a plurality of unit shapes are stackable to form an initial annular shape defining gaps;
said annular shape is reconfigured by breakage of said unit shapes into a shorter axial length and a greater diameter for said set position of said sealing element.

8. The plug of claim 1 , wherein:
said sealing element is formed principally of principally natural or synthetic sand but can also comprise at least some gravel, tempered glass, proppant, clay, Teflon®, swelling rubber or rubber or a combination thereof.

9. The plug of claim 1 , further comprising:
a cover over at least an exterior face of said sealing element and configured to begin failing with exposure to existing well conditions upon running in or later created well conditions;
wherein failing of said cover allows said material, which is granular, to disperse after a time of applied differential pressure against said plug so that the plug is removed from a subterranean location without further mechanical intervention at the subterranean location.

10. The plug of claim 9 , wherein:
said cover is over at least an exterior face of said sealing element.

11. The plug of claim 1 , wherein:
said mandrel is made from a material that disintegrates when exposed to existing or created conditions at the subterranean location.

12. The plug of claim 11 , wherein:
said mandrel is made from at least one controlled electrolytic material which is undermined by chemicals found at the subterranean location or added to the subterranean location from a surface or released from said sealing element being put into a set position.

13. The plug of claim 1 , wherein:
said sealing element comprises natural or synthetic sand held together by a binder that is selectively undermined when said sealing element is put into said set position.

14. The plug of claim 1 , wherein:
said mandrel comprises a through passage surrounded by a seat to accept an object that lands on said seat after said sealing element is in said set position.

15. The plug of claim 1 , wherein:
said sealing element is porous.

16. The plug of claim 1 , wherein:
said sealing element allows some or no leakage when set.

17. The plug of claim 1 , wherein:
said granular sealing element material grips in said set position.

18. The plug of claim 1 , wherein:
said sealing element is pushed radially with expansion of said mandrel.

19. The plug of claim 1 , wherein:
said sealing element is impervious.

20. A removable plug for subterranean use, comprising:
a mandrel made of a material that can be structurally compromised after a predetermined time with exposure to existing well conditions upon running in or later created well conditions;
a granular sealing element externally mounted to said mandrel for a run in and a set position created by an actuation assembly that selectively axially compacts said sealing element or pushes the sealing element radially to contact a surrounding borehole wall;
said sealing element essentially comprising at least one material, such that upon setting said sealing element in said set position said structural compromise of said mandrel allows said sealing element material to disperse after a time of applied differential pressure against said plug so that the plug is removed from a subterranean location;
said sealing element comprises pellets that encapsulate a chemical for release when said sealing element is placed in said set position;
said chemical undermines at least one of a binder for said granular sealing element, and said mandrel.

21. A removable plug for subterranean use, comprising:
a mandrel made of a material that can be structurally compromised after a predetermined time with exposure to existing well conditions upon running in or later created well conditions;
a sealing element externally mounted to said mandrel for a run in and a set position created by an actuation assembly that selectively axially compacts said sealing element or pushes the sealing element radially to contact a surrounding borehole wall;
said sealing element essentially comprising at least one material, such that upon setting said sealing element in said set position to a set position length and application of differential pressure against said plug while said sealing element maintains said set position length, said structural compromise of said mandrel from exposure to existing or subsequent well conditions allows said sealing element to disperse so that the plug is removed from a subterranean location;
a cover over an exterior face of said sealing element and configured to begin failing with exposure to existing well conditions upon running in or later created well conditions;
wherein failing of said cover allows said sealing element material, which is granular, to disperse after a time of applied differential pressure against said plug as said sealing element material maintains a length associated with the set position so that the plug is removed from a set subterranean location;
said cover fully surrounds said sealing element.

22. The plug of claim 21 , wherein:
said cover is porous.

23. The plug of claim 21 , wherein:
said cover comprises knitted Kevlar® or nylon.

24. The plug of claim 21 , wherein:
said cover is undermined by said sealing element when put into said set position.

25. The plug of claim 24 , wherein:
said sealing element contains particles that tear said cover.

Assignees

• Baker Hughes Inc
• Baker Hughes A Ge Co Llc

Inventors

• King James G
• Doane James C
• Harper Jason M
• Taylor Robert J
• Hernaez Erwin D

Classifications

• E21B33/1208 Primary

  characterised by the construction of the sealing or packing means (E21B33/1277 takes precedence) · CPC title

• E21B33/13

  Methods or devices for cementing, for plugging holes, crevices or the like · CPC title

• E21B43/14

  Obtaining from a multiple-zone well · CPC title

• E21B43/26

  by forming crevices or fractures · CPC title

• E21B2200/08

  Down-hole devices using materials which decompose under well-bore conditions · CPC title