Shock load mitigation in a downhole perforation tool assembly

• US 8,714,251 B2
• Filed: 08/25/2012
• Issued: 05/06/2014
• Est. Priority Date: 04/29/2011
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Glenn, Timothy S., Rodgers, John P., Nelson, Jeff A., Burleson, John D., Serra, Marco, Hales, John H.
• Primary Examiner(s): Ro, Yong-Suk (Philip)
• Application Number:
  US13/594,776
• Publication Number:
  US 20120318508A1
• Time in Patent Office: 619 Days
• Field of Search: 166/378, 166/55, 166/299, 166/297, 175/4.5, 175/4.55, 285/137.11, 285/141, 285/222, 285/331
• US Class Current: 166/297
• CPC Class Codes: E21B 17/07 Telescoping joints for varying drill string lengths; Shock absorbers
• CPC Class Codes: E21B 43/11 Perforators; Permeators
• CPC Class Codes: E21B 43/117 Shaped-charge perforators E21B43/118 takes precedence
• CPC Class Codes: G06F 30/17 Mechanical parametric or variational design

Abstract

A perforation tool assembly comprises an energy train, a first perforation gun, and a second perforation gun. The energy train comprises a moderator to reduce the speed of propagation of a detonation in a direction parallel to the axis of the perforation tool assembly. The first perforation gun comprises a plurality of explosive charges coupled to a first portion of the energy train. The second perforation gun comprises a plurality of explosive charges coupled to a second portion of the energy train, wherein the second portion of the energy train is coupled to the first portion of the energy train.

Claims

1. A perforation tool assembly, comprising:

a spacer;

an energy train comprising a first portion and a second portion, wherein the first portion of the energy train is disposed in the spacer, wherein the first portion of the energy train comprises a moderator, wherein the moderator is configured to reduce the speed of detonation through the first portion of the energy train in a direction parallel to the axis of the perforation tool assembly relative to the speed of detonation through the second portion of the energy train in the direction parallel to the axis of the perforation tool assembly, wherein the moderator reduces the speed of detonation through the first portion of the energy train relative to the speed of detonation through the second portion of the energy train by an amount in a range from 1% to 50%, and wherein the moderator comprises the first portion of the energy train having a longer length through the spacer than a straight path through the spacer;

a first perforation gun comprising a plurality of explosive charges coupled to a first portion of the energy train; and

a second perforation gun comprising a plurality of explosive charges coupled to a second portion of the energy train, wherein the second portion of the energy train is coupled to the first portion of the energy train.

2. The perforation tool assembly of claim 1, wherein the moderator is configured to reduce the speed of detonation in the direction parallel to the axis of the perforation tool assembly by an amount in a range from 15% to 30%.

3. The perforation tool assembly of claim 1, wherein the moderator further comprises a modified detonation cord comprising dilutants.

4. The perforation tool assembly of claim 3, wherein the dilutants comprise at least one of a sand or a fine clay.

5. The perforation tool assembly of claim 3, wherein the dilutants comprise a less energetic explosive compound.

6. The perforation tool assembly of claim 1, wherein the moderator further comprises delay elements incorporated in the energy train.

7. The perforation tool assembly of claim 1, wherein the perforation tool assembly comprises structures that alter a propagation of a shock wave through a tool body of the perforation tool assembly.

8. The perforation tool assembly of claim 7, wherein the structures that alter the propagation of the shock wave are selected from the group consisting of a mass energy absorber, a deformable energy absorber, a hydraulic shock absorber, a spacer providing an acoustic impedance mismatch, and a decoupler.

9. The perforation tool assembly of claim 7, wherein the structures that alter the propagation of the shock wave comprises the spacer, and wherein the spacer has a tool body composed of a composite material.

10. The perforation tool assembly of claim 7, wherein the perforation tool assembly is designed to offset a speed of shock wave propagation relative to the speed of detonation by at least 5%.

11. The perforation tool assembly of claim 1, wherein the perforation tool assembly comprises structures that alter the speed of detonation in the energy train in the direction parallel to the axis of the tool body of the perforation tool assembly relative to a speed of detonation in an energy train in a direction parallel to an axis of a tool body of a conventional perforation tool assembly.

12. The perforation tool assembly of claim 11, wherein the structures are selected from the group consisting of a spacer incorporating an indirect path into an energy train segment of the spacer, and a spacer incorporating a reduced speed detonation cord into an energy train segment of the spacer.

13. The perforation tool assembly of claim 11, wherein the structures are selected from a group consisting of a spacer incorporating a bullet firing gun as a portion of an energy train segment of the spacer, and a perforation gun incorporating a reduced speed detonation cord into an energy train segment of the perforation gun.

14. The perforation tool assembly of claim 1, wherein the first portion of the energy train is disposed through the spacer in at least one of a zig-zagged or a helical pattern.

15. The perforation tool assembly of claim 1, wherein the first portion of the energy train comprises a first portion of a detonation cord and the second portion of the energy train comprises a second portion of the detonation cord.

16. The perforation tool assembly of claim 15, wherein the moderator reduces the speed of detonation in the direction parallel to the axis of the perforation tool assembly through the first portion of the detonation cord.

17. The perforation tool assembly of claim 15, wherein the first portion of the detonation cord is in explosive communication with the second portion of the detonation cord.

18. The perforation tool assembly of claim 1, wherein the moderator is further configured to mitigate the shock load in the perforating tool assembly.

19. The perforation tool assembly of claim 1, wherein the energy train is parallel to the axis of the perforation tool assembly across the perforation tool assembly.

20. The perforation tool assembly of claim 1, wherein the second portion of the energy train comprises a detonation cord which is parallel to the axis of the perforating tool assembly across the perforating tool assembly.