DOWNHOLE DETECTION TOOL

• US 20160245947A1
• Filed: 10/07/2014
• Published: 08/25/2016
• Est. Priority Date: 10/07/2013
• Status: Active Grant

• Current Assignee: Guardian Global Technologies Limited (Core Laboratories NV)
• Original Assignee: Guardian Global Technologies Limited (Core Laboratories NV)
• Inventors: Clay, Oliver, Grigorov, Alexander, Moss, Paul, Maxted, Iain, Gore, Jonathan
• Granted Patent: US 10,520,634 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: E21B 43/116 Gun or shaped-charge perforators
• CPC Class Codes: E21B 47/09 Locating or determining the position of objects in boreholes or wells , e.g. the position of an extending arm; Identifying the free or blocked portions of pipes
• CPC Class Codes: E21B 47/092 by detecting magnetic anomalies
• CPC Class Codes: G01N 27/902 by moving the sensors
• CPC Class Codes: G01V 3/28 using induction coils

Abstract

The present invention concerns a downhole cable or control line detection tool. More particularly, but not exclusively, this invention concerns a method and apparatus for the downhole detection of a cable or control line associated with the external wall of a well casing. A downhole tool for the detection of downhole cable or control lines is provided. The downhole tool comprises an eddy current sensor, the eddy current sensor being arranged to be proximate to the internal wall of a well casing. The eddy current sensor is arranged for pulsed operation. The downhole tool further comprises a mechanism for rotating the eddy current sensor, with an axis of rotation parallel with the longitudinal axis of a well casing.

Claims

1. A downhole tool for the detection of downhole cable or control lines, the downhole tool comprising:

an eddy current sensor, the eddy current sensor being arranged to be proximate to the internal wall of a well casing, the eddy current sensor being arranged for pulsed operation, and

a mechanism for rotating the eddy current sensor, with an axis of rotation parallel with the longitudinal axis of a well casing.

2. A downhole tool as claimed in claim 1, the downhole tool comprising a control unit including a processing unit arranged to process the readings taken by the eddy current sensor.

3. A downhole tool as claimed in claim 2, wherein the control unit comprises a surface control unit.

4. A downhole tool as claimed in claim 2, the control unit being arranged to control the operation of the downhole tool.

5. A downhole tool as in claim 4, further comprising a telemetry cartridge.

6. A downhole tool as claimed in claim 5, wherein the telemetry cartridge is arranged to send data signals between the eddy current sensor and a control unit.

7. A downhole tool as in claim 2, comprising a control unit with a processing unit arranged to analyse the eddy current sensor readings and provide an indication of where downhole cable or control lines are detected at the outer wall of the well casing.

8. A downhole tool as claimed in claim 7, wherein the control unit comprises a memory unit arranged to record the location of any detected downhole cables or control lines.

9. A downhole tool as in claim 2, wherein the eddy current sensor comprises a receiver coil.

10. A downhole tool as in claim 9, wherein the eddy current sensor comprises a transmitter coil.

11. A downhole tool as in claim 10, wherein the receiver coil and transmitter coil are configured in a nested arrangement.

12. A downhole tool as in claim 1, wherein the downhole tool is configured to move the eddy current sensor in a longitudinal direction.

13. A downhole tool as in claim 1, wherein the downhole tool comprises a support arm, the eddy current sensor being located at a distal end of the support arm.

14. A downhole tool as claimed in claim 13, wherein the support arm is under bias, such that, in use, the eddy current sensor is pushed against the inner wall of a well casing.

15. A downhole tool as in claim 14, wherein the eddy current sensor comprises one or more rollers or skids, the rollers or skids configured to reduce friction with the inner wall of a well casing.

16. A method of detecting a downhole cable or control line running along the external wall of a well casing, comprising the steps of:

providing an eddy current sensor and locating the eddy current sensor in proximity to the internal wall of a well casing,

sending a pulse of current to the eddy current sensor, thereby generating a magnetic field, and creating eddy currents in the well casing,

measuring, using the eddy current sensor, the magnetic field generated by the eddy currents induced within the downhole cable or control line,

moving the eddy current sensor around the circumference of the internal wall of the well casing,

repeating the generating and measuring steps,

analysing the measurement results of the eddy current sensor, wherein the analysis identifies any readings which present a profile suggestive of a downhole cable or control line, and

recording the location corresponding any such readings.

17. A method as claimed in claim 16, wherein the analysis of eddy currents is performed by a computer processing unit, the computer processing unit comprising a computer program.

18. A method as claimed in claim 17, including the step of the eddy current sensor being calibrated prior to downhole deployment.

19. A method as claimed in claim 18, wherein the calibration comprises repeating the method steps on a well casing of known properties.

20. A method as in claim 19, including the step of moving the eddy current sensor in a longitudinal direction.

21. A method of planning a perforation pattern for a well casing, the method comprising the steps of detecting the location of downhole cable or control lines running along the external wall of the well casing according to the method as claimed in claim 16, and plotting a perforation pattern such that the perforations will not damage any of said downhole cable or control lines.

22. (canceled)

23. (canceled)