Safety system for autonomous downhole tool

Patent metadata

Field	Value
Publication number	US-9903192-B2
Application number	US-201214005166-A
Country	US
Kind code	B2
Filing date	Mar 9, 2012
Priority date	May 23, 2011
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

A tool assembly for performing a wellbore operation including an actuatable tool, a location device, and on-board controller are together dimensioned and arranged to be deployed in the wellbore as an autonomous unit. The actuatable tool, such as a perforating gun having associated charges, perforates a wellbore along a selected zone of interest. The location device, such as casing collar locator, senses the location of the actuatable tool based on a physical signature provided along the wellbore. The on-board controller or micro-processor is configured to send an activation signal to the actuatable tool when the location device has recognized a selected location of the tool based on the physical signature. The tool assembly further includes a multi-gate safety system. The safety system prevents premature activation of the actuatable tool.

First claim

What is claimed is:

1. A tool assembly for performing a wellbore operation, comprising:
an actuatable tool;
a location device for sensing the location of the actuatable tool within a wellbore based on a physical signature provided along the wellbore;
an on-board controller configured to send an actuation signal to the actuatable tool when the location device has recognized a selected location of the tool based on the physical signature, wherein the actuatable tool, the location device, and the on-board controller are together dimensioned and arranged to be deployed in the wellbore as an autonomous unit;
a multi-gate safety system in communication with the on-board controller for preventing premature activation of the actuatable tool, the multi-gate safety system comprising;
(i) control circuitry having one or more electrical switches that are independently operated by the controller in response to separate conditions before permitting the actuation signal to reach the actuatable tool, and
(ii) a first on-board power supply for the on-board controller,
(iii) a second on-board power supply for actuating the actuatable tool; and

a firing capacitor in communication with the on-board controller, wherein at least one of the electrical switches of the multi-gate safety system controls charging of the firing capacitor by the second on-board power supply wherein the firing capacitor is insufficiently charged to activate the actuatable tool prior to the multi-gate safety system permitting the controller to initiate charging of the firing capacitor.

2. The tool assembly of claim 1 , wherein the multi-gate safety system comprises at least one of:
(i) the first on-board power supply includes a selectively removable battery pack, wherein the battery pack provides power to the control circuitry when the battery pack is installed into the assembly;
(ii) a mechanical pull-tab, wherein the control circuitry is configured to operate an electrical switch upon removal of the tab from the tool assembly;
(iii) a pressure-sensitive electrical switch that operates only when a designated hydraulic pressure on the tool assembly is exceeded;
(iv) an electrical timer that is configured to selectively operate an electrical switch at a designated times after deployment of the tool assembly in the wellbore;
(v) a velocity sensor configured to operate an electrical switch upon sensing that the tool assembly is traveling at a designated velocity;
(vi) a sensor configured to actuate an electrical switch when the tool assembly is substantially vertical; and
(vii) a sensor configured to actuate an electrical switch when the tool assembly is substantially horizontal;
wherein operating an electrical switch means either closing such a switch to permit a flow of electrical current through the switch, or opening such a switch to restrict a flow of electrical current through the switch.

3. The tool assembly of claim 2 , wherein:
the tool assembly is a perforating gun assembly; and
the actuatable tool comprises a perforating gun having detonators with associated charges that detonate in response to an electrical signal conveyed through one or more electrical wires, wherein the detonation is powered by the second on-board power supply charging the firing capacitor.

4. The tool assembly of claim 3 , wherein:
the one or more wires comprises a pair of wires that are configured to receive an electrical charge from the firing capacitor;
the multi-gate system comprises the electrical timer; and
the one or more switches operated by the electrical timer comprises a shunt switch.

5. The tool assembly of claim 4 , wherein:
during a first designated time, the shunt switch is closed; and
at a second designated time, the shunt switch is open.

6. The tool assembly of claim 5 , wherein:
the first designated time is about 1 to 5 minutes; and
the second designated time is about 4 to 60 minutes.

7. The tool assembly of claim 4 , wherein:
the multi-gate system comprises the electrical timer;
the one or more switches comprises a detonator switch that resides in an open state during a first designated period of time;
the electrical timer is configured to send a command signal to the detonator switch to close the detonator switch at a second designated time.

8. The tool assembly of claim 7 , wherein at a third designated time, the shunt switch is again open.

9. The tool assembly of claim 3 , wherein:
the perforating gun assembly is substantially fabricated from a friable material; and
the perforating gun assembly self-destructs in response to the associated charges detonating.

10. The tool assembly of claim 3 , wherein:
the multi-gate safety system comprises both the mechanical pull-tab and the timer switch; and
deployment of the tool assembly means that the tool assembly is configured for removal of the mechanical pull-tab.

11. The tool assembly of claim 10 , wherein:
the mechanical pull-tab is releasably connected to a cable;
the cable is tethered to a wellhead component over the wellbore; and
the mechanical pull-tab is configured to release upon movement of the tool assembly into the wellbore.

12. The tool assembly of claim 3 , further comprising:
a shunt comprising two leads, wherein the shunt is configured to direct electrical current through the leads in a closed position, and to permit a flow of current toward the actuatable tool in an open position.

13. The tool assembly of claim 12 , wherein:
the multi-gate system comprises the electrical timer; and
the one or more switches operated by the electrical timer comprises (i) a switch for closing a connection between the removable battery pack and the control circuitry, (ii) a switch for operating a connection between the firing capacitor and the two leads, (iii) or a combination of the two.

14. The tool assembly of claim 3 , wherein:
the multi-gate safety system comprises both the mechanical pull-tab and the pressure sensitive switch; and
the mechanical pull-tab is configured to provide a mechanical barrier for the activation of the pressure-sensitive switch.

15. The tool assembly of claim 14 , wherein the pressure-sensitive switch comprises either a diaphragm or a spring-biased connection.

16. The tool assembly of claim 3 , further comprising:
a fishing neck.

17. The tool assembly of claim 3 , wherein:
the on-board controller is part of an electronic module comprising onboard memory and built-in logic; and
the electronic module is configured to send a signal that initiates detonation of the perforating gun after the tool assembly has traveled to a pre-programmed location in the wellbore.

18. The tool assembly of claim 17 , wherein the built-in logic provides a digital safety barrier based on a predetermined value for (i) tool depth, (ii) tool speed, (iii) travel time, (iv) downhole markers, or (v) combinations thereof.

19. The tool assembly of claim 3 , wherein the multi-gate safety system comprises:
the electrical timer switch; and
a mechanical relay having a timer, wherein the timer for the mechanical relay is configured to activate after the electrical timer switch is closed, and to switch the mechanical relay after a pre-set period of time has passed in order to re-open the electrical timer switch.

20. The tool assembly of claim 3 , wherein the multi-gate safety system comprises:
the selectively removable battery pack; and
a relay that connects the battery pack to a discharge bank to draw down electrical power from the battery pack.

Assignees

• Entchev Pavlin B
• Angeles Boza Renzo M
• King George R
• Stanton Robert C
• Winemiller Elton
• Tolman Randy C
• Sauermilch Peter W
• Gahr Jason Z
• Exxonmobil Upstream Res Co

Inventors

• Entchev Pavlin B
• Angeles Boza Renzo M
• King George R
• Stanton Robert C
• Winemiller Elton
• Tolman Randy C
• Sauermilch Peter W
• Gahr Jason Z

Classifications

• E21B43/26

  by forming crevices or fractures · CPC title

• E21B33/1204 Primary

  permanent; drillable · CPC title

• E21B44/005

  Below-ground automatic control systems · CPC title

• E21B43/263 Primary

  using explosives · CPC title

• E21B43/119

  Details, e.g. for locating perforating place or direction · CPC title