Hydraulic underbalance initiated safety firing head, well completion apparatus incorporating same, and method of use

Patent metadata

Field	Value
Publication number	US-10865626-B2
Application number	US-201816190465-A
Country	US
Kind code	B2
Filing date	Nov 14, 2018
Priority date	Nov 29, 2017
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

A firing head assembly is described. The firing head assembly includes a tubular housing, upper piston and lower pistons, and a compressible member arranged within a lumen of the tubular housing and positioned between the upper and lower pistons. According to an aspect, the assembly includes a safety assembly that includes a sleeve having a zigzag shaped slot therein. The safety assembly may include a key that radially extends from a surface of one of the pistons, through the zigzag shaped slot. The distance between the upper and lower pistons may be adjusted by adjusting a pressure inside the tubular housing and a second pressure outside the tubular housing. The upper and lower pistons may function to operatively adjust the arrangement of the key within the zigzag shaped slot to activate the firing head assembly to either trigger an explosive reaction or to not trigger the explosive reaction.

First claim

What is claimed is:

1. A firing head assembly, comprising:
a tubular housing having a first end, a second end, and a lumen extending between the first end and the second end;
an upper piston slidably disposed proximate to the first end of the tubular housing and at least partially extending into the lumen of the tubular housing;
a lower piston secured proximate the second end of the tubular housing and at least partially extending into the lumen of the tubular housing;
a compressible member comprising a first end portion and a second end portion, wherein the first end portion abuts the upper piston and the second end portion abuts the lower piston, and wherein the compressible member is within the lumen of the tubular housing;
a safety assembly comprising a sleeve and a key, the sleeve comprising a substantially zigzag-shaped slot having a plurality of stop points, and the key radially extending from an external surface of the upper piston through the zigzag-shaped slot, wherein the key is slidably arranged within the zigzag-shaped slot and engages with at least one of the plurality of stop points of the zigzag-shaped slot;
a first securing element positioned along the second end of the tubular housing and operative for retaining the lower piston in the tubular housing; and
a firing pin positioned below the lower piston and retained in a spaced apart configuration from the lower piston by a second securing element, such that the first securing element releases the lower piston prior to the second securing element releasing the firing pin,
wherein the upper piston operatively adjusts the arrangement of the key within the zigzag-shaped slot to activate the firing head assembly.

2. The firing head assembly of claim 1 , wherein the compressible member is adjustable between a maximum length, a minimum length, and a plurality of intermediate lengths therebetween, each of the maximum length, the minimum length, and the intermediate lengths corresponding to a position of the key in the zigzag-shaped slot.

3. The firing head assembly of claim 1 , further comprising:
a percussion initiator positioned below the firing pin,
wherein the firing pin is retained in a spaced apart configuration from the percussion initiator by the second securing element.

4. The firing head assembly of claim 3 , wherein the compressible member comprises
a spring or a coil.

5. The firing head assembly of claim 3 , further comprising a plurality of sealing members, wherein:
at least one sealing member is positioned between the upper piston and the lumen of the tubular housing; and
at least one other sealing member is positioned between the lower piston and the lumen of the tubular housing,
wherein when the firing head assembly is positioned in a wellbore, the sealing members are operative for isolating the compressible member from a wellbore fluid within the wellbore, the wellbore fluid having a wellbore pressure.

6. The firing head assembly of claim 5 , wherein:
the upper piston and the tubular housing at least partially define an upper chamber of the lumen disposed above the upper piston, the upper chamber having a first pressure; and
the lower piston and the tubular housing at least partially define a lower chamber of the lumen disposed below the lower piston, the lower chamber having a second pressure, wherein
the compressible member is in an intermediate chamber of the lumen disposed between the upper chamber and the lower chamber, the intermediate chamber having a third pressure.

7. The firing head assembly of claim 6 , wherein:
the lower chamber comprises a port that fluidly connects the wellbore to the lower chamber, so that the second pressure is the same as the wellbore pressure, and the first pressure is different from the second pressure; or
the upper chamber and the lower chamber each comprise a respective port that fluidly connects the wellbore to the upper chamber and the lower chamber, so that the first pressure and the second pressure are each the same as the wellbore pressure.

8. The firing head assembly of claim 7 , wherein:
an increase of the first pressure moves the upper piston downwards and adjusts the compressible member to a compressed state and moves the key generally downwardly in the zigzag-shaped slot; and
a subsequent decrease of the first pressure adjusts the compressible member to a partially compressed state and moves the key generally upwardly into the next position of the zigzag-shaped slot.

9. The firing head assembly of claim 8 , wherein:
the compressible member is operative for generating a compressive force and applying the compressive force onto the lower piston; and
the lower piston is operative for contacting the firing pin, thus shearing the second securing element and moving the firing pin downwardly towards the percussion initiator to apply a downward force to the percussion initiator and trigger an explosive reaction.

10. The firing head assembly of claim 8 , wherein when the upper chamber and the lower chamber each comprise the respective port that fluidly connects the wellbore to the upper chamber and the lower chamber, the first pressure and the second pressure are adjusted by at least one of:
moving the firing head assembly downwardly or upwardly in the wellbore; and
adding or removing a fluid from the wellbore, wherein
a decrease of the first and second pressures until they are less than the third pressure generates a force across the first securing element, and when the force across the first securing element is less than the compressive force generated by the compressible member, the first securing element breaks and releases the lower piston, so that the lower piston moves downwardly to strike and break the second securing element, thus releasing the firing pin and allowing the firing pin to apply a downward force to the percussion initiator to trigger an explosive reaction.

11. The firing head assembly of claim 1 , wherein the compressible member comprises a pressurized gas disposed between the upper piston and the lower piston, the pressurized gas being isolated within the lumen of the tubular housing.

12. A well completion apparatus comprising:
a perforating gun; and
a firing head assembly operably associated with the perforating gun, the firing head assembly comprising;
a tubular housing having a first end, a second end, and a lumen extending between the first and second ends;
an upper piston disposed proximate the first end of the tubular housing, wherein the upper piston partially extends into the lumen of tubular housing and is slidably moveable within at least a portion of the lumen;
a lower piston secured proximate the second end of the tubular housing by a first securing element and at least partially extending into the lumen of the tubular housing;
a compressible member positioned within the lumen, wherein the compressible member is adjustable between a relaxed state, a compressed state and a partially compressed state, and comprises a first end portion and a second end portion, the first end portion abutting the upper piston and the second end portion abutting the lower piston;
a safety assembly comprising a sleeve and a key, the sleeve comprising a zigzag-shaped slot having a plurality of stop points, wherein each stop point is spaced apart from an adjacent stop point, and wherein the key radially extends from an external surface of the upper piston through the zigzag-shaped slot, is slidably arranged within the zigzag-shaped slot, and is moveable between each stop point to activate and deactivate the firing head assembly; and
a firing pin positioned below the lower piston and retained in a spaced apart

Assignees

• DynaEnergetics Europe GmbH

Inventors

• Preiss Frank Haron
• Mulhern Eric

Classifications

• E21B43/11852 Primary

  hydraulically actuated · CPC title

• E21B23/006

  "J-slot" systems, i.e. lug and slot indexing mechanisms · CPC title

• E21B43/11857

  firing indication systems · CPC title

• E21B23/04

  operated by fluid means, e.g. actuated by explosion (E21B23/08 takes precedence) · CPC title