Casings for use in a system for fracturing rock within a bore

Patent metadata

Field	Value
Publication number	US-2016153272-A1
Application number	US-201414905361-A
Country	US
Kind code	A1
Filing date	Jul 15, 2014
Priority date	Jul 15, 2013
Publication date	Jun 2, 2016
Grant date	—

Abstract

In disclosed explosive units for use in a wellbore, the casing can include a tubular outer body comprising grooves, pockets, or other variances in thickness that create stress concentrations that promote shear and tensile fragmentation instead of ductile expansion of the casing, which can negatively impact permeability of a wellbore. In other embodiments, the casing can comprise non-ductile and/or reactive material which responds to explosive or high temperature loading by brittle failure, disintegration, melting, burning, and/or chemically reacting with the energetic materials and/or the borehole environment. Such embodiments can enhance the permeability of the wellbore after detonation.

First claim

We claim:

1 . A system comprising:
a plurality of casings coupled together for containing explosive material for detonation to fracture rock in a bore into which the plurality of coupled together casings have been inserted; the casings each comprising an elongated body comprising a wall having an interior surface and an exterior surface and comprising a casing material; and the casings being configured so as to prevent a substantially continuous and substantially impermeable coating of the bore by the casing material upon detonation of the explosive material.

2 . The system of claim 1 , wherein the casings are configured to at least partially decompose upon detonation of the explosive

3 . The system of claim 2 , wherein the casings are comprised of aluminum and wherein an aluminum oxidizer is positioned within the casing, the oxidizer being operable to at least partially oxidize and thereby at least partially decompose the casing upon detonation of the explosive.

4 . The system of claim 3 , comprising the casings in combination with an explosive and oxidizer in the form of a powder or a sponge-like material.

5 . The system of claim 2 , wherein the casings are comprised of an oxidizable material that oxidizes in the presence of an oxidizer to at least partially decompose the casing upon detonation of the explosive, the oxidizer reacting with the oxidizable material of the casings upon detonation of the explosive to at least partially decompose the casings.

6 . The system of any one of claim 3 , 4 or 5 wherein the oxidizer is provided at least in a layer adjacent to the interior surface of the wall of the casings.

7 . The system of claim 2 , wherein the casings are comprised of a polymer material that at least partially decomposes by melting upon detonation of the explosive.

8 . The system of claim 7 , wherein the casings are comprised of a thermoset or thermoplastic material.

9 . The system of claim 8 , wherein the casings are comprised of ABS plastic.

10 . The system of claim 8 , 9 or 10 , wherein the casings comprise a composite material reinforced with fibers.

11 . The system of claim 10 , wherein the fibers comprise one or more of fiberglass, carbon fibers, or aramid fibers.

12 . The system of claim 10 , wherein the fibers comprise flammable fibers that decompose by burning upon detonation of the explosive.

13 . The system of claim 12 , wherein the flammable fibers comprise cellulosic fibers.

14 . The system of claim 1 , wherein the casings comprise a body comprising a chemically reactive material that responds to detonation of the explosive material within the casing by chemically reacting with a reactive material contained within the body.

15 . The system of claim 1 , wherein the casings at least partially disintegrate in response to detonation of explosive material within the casings.

16 . The system of claim 1 , wherein each casing body comprises stress concentrations positioned such that the wall of the body is configured to fragment into a plurality of smaller pieces upon detonation of explosive material within the casing.

17 . The system of claim 16 , wherein the stress concentrations comprise grooves.

18 . The system of claim 17 , wherein the grooves comprise longitudinally extending grooves and circumferentially extending grooves that intersect one another.

19 . The system of claim 17 , wherein the grooves comprise helically extending grooves.

20 . The system of any one of claim 16 , 17 , 18 , 19 or 20 , wherein the casing bodies comprise a plurality of thick portions and a plurality of thin portions.

21 . The system of claim 20 , wherein transitions between the thick portions and the thin portions comprise the stress concentrations.

22 . The system of claim 21 , wherein the thin portions comprise recessed pockets in at least one surface of the interior and exterior surfaces of the wall of the body.

23 . The system of any one of claim 16 , 17 , 18 or 19 , wherein the casing bodies comprise a non-ductile material that responds to detonation of explosive materials within the casing by brittle failure.

24 . The system of claim 1 , wherein the casing bodies are configured to decompose into particulate or granular matter in response to detonation of the explosive materials.

25 . A casing for an explosive unit for use in fracturing a geologic formation around a bore, the casing comprising:
a tubular body having a first longitudinal end portion, a second longitudinal end portion, an outer surface, and an inner surface; first and second end caps secured to the first and second longitudinal end portions of the tubular body, such that the casing defines an internal region configured to contain an explosive material; wherein, upon detonation of explosive material within the casing within a bore in a geologic formation, the casing is configured to fracture or decompose to release explosive energy into the geologic formation without substantially limiting the permeability of the bore and the geologic formation around the bore.

26 . The casing of claim 25 , wherein the tubular body comprises stress concentrations such that the tubular body is configured to fragment into a plurality of smaller pieces upon detonation of explosive material within the casing.

27 . The casing of claim 26 , wherein the stress concentrations comprise grooves in the outer surface of the tubular body.

28 . The casing of claim 27 , wherein the grooves comprise longitudinally extending grooves and circumferentially extending grooves that intersect one another.

29 . The casing of claim 27 , wherein the grooves comprise helically extending grooves.

30 . The casing of any one of claim 25 , 26 , 27 , 28 or 29 , wherein the tubular body comprises a plurality of thick portions and a plurality of thin portions.

31 . The casing of claim 30 , wherein transitions between the thick portions and the thin portions comprise the stress concentrations.

32 . The casing of claim 31 , wherein the thin portions comprise recessed pockets in a surface of the tubular body.

33 . The casing of any one of claim 25 , 26 , 27 , 28 or 29 , wherein the tubular body comprises a non-ductile material that responds to detonation of explosive material within the casing by brittle failure.

34 . The casing of claim 33 , wherein the tubular body comprises a plurality of thick portions and a plurality of thin portions.

35 . The casing of claim 34 , wherein transitions between the thick portions and the thin portions comprise the stress concentrations.

36 . The casing of claim 35 , wherein the thin portions comprise recessed pockets in the outer surface of the tubular body.

37 . The casing of claim 25 , wherein the tubular body comprises a chemically reactive material that responds to detonation of explosive material within the casing by chemically reacting with energetic material released by the detonation.

38 . The casing of claim 25 , wherein the tubular body disintegrates in response to detonation of explosive material within the casing.

39 . The casing of claim 25 , wherein the tubular body comprises

Assignees

• Los Alamos Nat Security Llc
• Los Almos Nat Security Llc

Inventors

• Mace Jonathan Lee
• Bronisz Lawrence E
• Steedman David W
• Brandy Christopher Robert

Classifications

• E21B43/263 Primary

  using explosives · CPC title

• F42D3/00

  Particular applications of blasting techniques {(explosive welding B23K20/08; explosive bolts or actuators F42B3/006; explosive valves F16K13/06; cutting devices actuated by explosion B23D15/145; pyrotechnical actuators F15B15/19; switching devices actuated by explosion H01H39/00)} · CPC title

• F42D1/22

  Methods for holding or positioning for blasting cartridges or tamping cartridges · CPC title

• F42B3/02

  adapted to be united into assemblies · CPC title