Disintegrating Agglomerated Sand Frack Plug

• US 20150211324A1
• Filed: 01/24/2014
• Published: 07/30/2015
• Est. Priority Date: 01/24/2014
• Status: Active Grant

• Current Assignee: Baker Hughes Holdings LLC (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: King, James G., Doane, James C., Harper, Jason M., Taylor, Robert J., Hernaez, Erwin D.
• Granted Patent: US 10,018,010 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: E21B 33/1208 characterised by the construction of the sealing or packing means E21B33/1277 takes precedence
• CPC Class Codes: E21B 33/13 Methods or devices for cementing, for plugging holes, crevices or the like
• CPC Class Codes: E21B 43/14 Obtaining from a multiple-zone well
• CPC Class Codes: E21B 43/26 by forming crevices or fractures

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.

Claims

1. 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 supported by 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;

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 granular material to disperse after a time of applied differential pressure against said plug so that the plug is removed from its set subterranean location without further mechanical intervention at the subterranean location.

2. The plug of claim 1, wherein:

said material is a granular material and 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 material 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 material is granular and formed into at least one initial unit shape;

said unit shape is broken when said sealing element is in said set position.

7. The plug of claim 6, wherein:

said at least one unit shape comprises a plurality of unit shapes that are stackable to form an initial annular shape;

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, wherein:

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 material which is granular, said cover and said mandrel.

10. 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 its set subterranean location without further mechanical intervention at the subterranean location.

11. The plug of claim 10, wherein:

said cover is over at least an exterior face of said sealing element.

12. The plug of claim 11, wherein:

said cover fully surrounds said sealing element.

13. The plug of claim 11, wherein:

said cover is porous or impervious.

14. The plug of claim 13, wherein:

said cover comprises knitted Kevlar®

or nylon.

15. The plug of claim 10, wherein:

said cover is undermined by said sealing element when put into said set position.

16. The plug of claim 15, wherein:

said sealing element contains a chemical that is released.

17. The plug of claim 15, wherein:

said sealing element contains particles that tear said cover.

18. 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.

19. The plug of claim 18, wherein:

said mandrel is made from CEM 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 its set position.

20. 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.

21. 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.

22. The plug of claim 1, wherein:

said sealing element is porous or impervious.

23. The plug of claim 1, wherein:

said sealing element allows some or no leakage when set.

24. The plug of claim 1, wherein:

said material of said sealing element is granular and used to grip in set position.

25. The plug of claim 1, wherein:

said sealing element is pushed radially with expansion of said mandrel.

26. The plug of claim 1, wherein:

said sealing element is pushed radially with axial movement relative to a ramp.

27. A completion method for subterranean use, comprising:

running in at least one 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;

running in at least one sealing element supported by 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;

making said sealing element of at least one material;

setting said sealing element in said set position;

performing a completion operation against said sealing element in said set position;

initiating structural compromise of said mandrel to allow said granular material to disperse said performing so that the plug is removed from its set subterranean location without further mechanical intervention at the subterranean location.

28. The method of claim 27, comprising:

fracturing a formation during said completion operation.

32. The method of claim 27, comprising:

making said material granular.

33. The method of claim 32, comprising:

retaining said granular material with a binder.

34. The method of claim 33, comprising:

compromising said binder when said sealing element is in said set position.

35. The method of claim 33, comprising:

compromising said binder with a material released from within said sealing element.

36. The method of claim 35, comprising:

providing an encapsulated chemical in said sealing element that is released when said sealing element is axially compressed to said set position.

37. The method of claim 27, comprising:

providing said material in granular form and forming said granular material into at least one initial unit shape;

said unit shape is broken when said sealing element is in said set position.

38. The method of claim 37, comprising:

said at least one unit shape comprises a plurality of unit shapes that are stackable to form an initial annular shape;

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.

39. The method of claim 27, comprising:

forming said sealing element 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.

29. 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;

an anchor element supported by said mandrel for a run in and a set position created by an actuation assembly that selectively axially compacts said anchor element or pushes the anchor element radially against a surrounding borehole wall;

said anchor element resisting applied differential pressure thereto;

said anchor element essentially comprising at least one material, such that upon setting said anchor element in said set position said structural compromise of said mandrel allows said granular material to disperse after a time of applied differential pressure against said plug so that the plug is removed from its set subterranean location without further mechanical intervention at the subterranean location.

30. The plug of claim 29, wherein:

said anchor element at least partially seals to the borehole wall.

31. The plug of claim 30, wherein:

said anchor element fully seals to the borehole wall.

40. The method of claim 29, comprising:

said material is a granular material.