Determining Perforation Orientation

• US 20140208843A1
• Filed: 08/24/2012
• Published: 07/31/2014
• Est. Priority Date: 08/26/2011
• Status: Active Grant

• Current Assignee: Optasense Holdings Limited (Luna Innovations, Inc.)
• Original Assignee: Optasense Holdings Limited (Luna Innovations, Inc.)
• Inventors: Godfrey, Alastair
• Granted Patent: US 9,945,215 B2
• Time in Patent Office: Days
• US Class Current: 73/152.58
• CPC Class Codes: E21B 43/119 Details, e.g. for locating perforating place or direction
• CPC Class Codes: E21B 47/0224 using seismic or acoustic means
• CPC Class Codes: E21B 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• CPC Class Codes: E21B 47/135 using light waves, e.g. infrared or ultraviolet waves
• CPC Class Codes: G01V 11/005 Devices for positioning logging sondes with respect to the borehole wall centralising devices for drilling rods or pipes E21B17/10; setting or locking tools in boreholes E21B23/00; locating objects in boreholes E21B47/09

Abstract

A method and apparatus for determining the relative orientation of objects downwell, and especially to determining perforator orientation, involves varying the orientation of an object, such as a perforator gun (302) in the wellbore (202) and activating at least one directional acoustic source (402a-c). Each directional acoustic source is fixed in a predetermined location to the object and transmits an acoustic signal preferentially in a known direction. The directional acoustic sources are activated so as to generate sound in a plurality of different orientations of said object. An optical fibre (104) is interrogated to provide distributed acoustic sensing in the vicinity of the object; and the acoustic signals detected by the optical fibre are analysed to determine the orientation of the at least one directional acoustic source relative to the optical fibre, for instance by looking at the relative intensity in the different orientations.

Claims

1. A method of orienting an object in a wellbore comprising:

varying the orientation of the object in the wellbore;

activating at least one directional acoustic source arranged in fixed relation to said object so as to generate sound in a plurality of different orientations of said object;

interrogating an optical fibre deployed down the wellbore to provide distributed acoustic sensing in the vicinity of the object; and

analysing acoustic signals detected by the optical fibre so as to determine the orientation of the at least one directional acoustic source relative to the optical fibre.

2. A method as claimed in claim 1 wherein the acoustic signals are analysed to determine the relative intensity of the detected acoustic signals.

3. A method as claimed in claim 2 comprising analysing the detected signals to determine the orientation of the object which leads to the greatest detected acoustic intensity.

4. A method as claimed in claim 1 comprising positioning the object at the required position in the well and monitoring the acoustic signals detected by the optical fibre as the object is rotated through various orientations.

5. A method as claimed in claim 1 wherein the at least one directional acoustic source comprises at least one of (i) a loudspeaker in a suitable housing to provide directionality (ii) an acoustic source fixed to or forming part of the object or (iii) an acoustic source configured to transmit preferentially in a direction relative to an orientation of the object.

8. A method as claimed in claim 1 wherein the at least one directional acoustic source transmits at a predefined frequency.

9. A method as claimed in claim 8 comprising analysing the detected signals for said predetermined frequency.

10. A method as claimed in claim 1 wherein the frequency transmitted by at least one directional acoustic source is varied over time.

11. A method as claimed in claim 10 wherein (i) the frequency is varied during a period of continuous transmission or (ii) said source transmits a first frequency for a first period and then at least a second frequency for at least a second period.

13. A method as claimed in claim 1 wherein (i) the at least one directional acoustic source is configured to transmit constantly as the object is re-oriented or (ii) the object is oriented to a first position and one or more acoustic sources activated and then stopped prior to changing the orientation of the object.

15. A method as claimed in claim 1 wherein the object is provided with more than one directional acoustic source with at least some acoustic sources being arranged to transmit in different directions.

16. A method as claimed in claim 15 wherein (i) each acoustic source is activated in a sequence and the acoustic signals corresponding to each source analysed together or (ii) at least some of the plurality of directional acoustic sources transmit at different frequencies to one another.

20. A method as claimed in claim 1 wherein (i) the at least one directional acoustic source is pre-programmed to activate at certain times or (ii) the at least one directional acoustic source is controlled from the surface via a data link.

22. A method as claimed in claim 1 wherein the optical fibre is attached to the outside of a well casing.

23. A method as claimed in claim 1 wherein the method is used in addition to magnetic anomaly techniques.

24. A method as claimed in claim 1 wherein the object is a well perforator.

25. A method of perforating a well comprising using the method as claimed in claim 1 which is a method of perforating a well that comprises determining the orientation of a perforator relative to the optical fibre, orienting the perforator to avoid the optical fibre and firing the perforator.

6-7. -7. (canceled)

12. (canceled)

14. (canceled)

17-19. -19. (canceled)

21. (canceled)

26. A method of processing signals acquired from a distributed acoustic sensor comprising:

taking a plurality of measurement signals acquired when an object having at least one directional acoustic source is located downwell and wherein said signals correspond to a plurality of orientations of said object and processing the measurement signals to determine the orientation of said object relative to the optical fibre.

27. (canceled)

28. The use of DAS sensing to determine the orientation of objects, having directional acoustic sources, in a wellbore.

29. A distributed acoustic sensing apparatus for determining the location of an object downwell comprising an interrogator unit configured to, in use, interrogator an optical fibre deployed downwell to provide distributed acoustic sensing and a processor configured to take a plurality of measurement signals acquired when an object having at least one directional acoustic source is located downwell wherein said signals correspond to a plurality of orientations of said object and process the measurement signals to determine the orientation of said object relative to the optical fibre.

30. A well perforator having at least one directional acoustic source located in a fixed orientation relative to a perforation detector.