Observation of vibration of rotary apparatus

Patent metadata

Field	Value
Publication number	US-10550684-B2
Application number	US-201415031147-A
Country	US
Kind code	B2
Filing date	Oct 21, 2014
Priority date	Oct 21, 2013
Publication date	Feb 4, 2020
Grant date	Feb 4, 2020

Abstract

The operation of rotary equipment carried on elongate structure such as coiled tubing extending into a borehole from the Earth's surface is carried out by providing at least one optical fibre extending downhole to the rotary equipment from the surface, using optical time domain reflectometry to operating the optical fibre as a distributed vibration sensor while the rotary equipment is in operation, and thereby observing vibration created by the rotary equipment.

First claim

The invention claimed is:

1. A method of monitoring the operation of rotary equipment carried on elongate structure extending into a borehole from the Earth's surface, comprising:
providing at least one optical fibre extending downhole to the rotary equipment from the surface, the rotary equipment including a downhole motor coupled to a cutting tool;
operating the optical fibre as a distributed vibration sensor while operating the rotary equipment and using the downhole motor and cutting tool to mill materials within the wellbore, the materials within the wellbore including a plug positioned above a downhole end of the wellbore; and
observing vibration created by the rotary equipment, which includes:
detecting a change from a first signature of vibration of the downhole motor to a second signature of the vibration of the downhole motor;
correlating the change from the first signature to the second signature with a change in the materials of the plug being milled by the cutting tool; and
in response to the change from the first signature to the second signature, recommending a change in at least one of rotation speed or weight on bit;

wherein operating the optical fibre as a distributed vibration sensor is carried out with an optical time domain reflectometry system capable of:
transmitting pulses of coherent light into the at least one optical fibre; and
detecting backscattered light which is coherent Rayleigh noise.

2. The method of claim 1 wherein the elongate structure is coiled tubing.

3. The method of claim 1 wherein the at least one optical fibre extends downhole inside the elongate structure.

4. The method of claim 1 wherein the at least one optical fibre is single mode optical fibre.

5. The method of claim 1 wherein the at least one optical fibre is enclosed in a protective tube.

6. The method of claim 1 wherein the optical time domain reflectometry system:
provides a first optical signal output from a narrowband optical source in a first optical path and provides a second optical signal output from the narrowband optical source in a second optical path;
modulates the first optical signal to generate a plurality of pulses of light;
transmits the pulses along the at least one optical fibre;
mixes Rayleigh backscatter signals with the second optical signal to generate intermediate frequency (IF) signals;
determines phase of the IF signals at a plurality of locations along the optical fibre; and
detects change along the length of the optical fibre based on differences in the determined phases across a selected interval between the plurality of locations.

7. The method of claim 1 wherein processing data from the optical time domain reflectometry system comprises an action of comparing information from light backscattered from a succession of transmitted light pulses to observe strain along the length of the fibre, and carrying out that action repeatedly so as to observe changes in strain over time.

8. The method of claim 7 further comprising deriving one or more vibration frequencies from the changes in strain over time.

9. The method of claim 8 further comprising comparing the derived vibration frequencies with a database of recorded vibration frequencies.

10. The method of claim 1 wherein the at least one optical fibre is secured to the rotary equipment.

11. The method of claim 10 wherein a surface end of the at least one optical fibre is anchored at or near surface and a downhole end of the at least one optical fibre is anchored at a downhole end of coiled tubing forming the elongate structure.

12. The method of claim 11 wherein the at least one optical fibre is loose between the surface and downhole ends of the coiled tubing.

13. The method of claim 1 further comprising operating the optical fibre as a communication link.

14. The method of claim 13 wherein operating the optical fibre as a communication link is carried out with one or more sensors connected to an electronics package to encode signals from the one or more sensors to light signals, and transmitting the light signals to the surface along the at least one optical fibre.

15. The method of claim 1 wherein a portion of the at least one optical fibre is wound helically around the exterior of the rotary equipment.

16. The method of claim 15 wherein the helically wound portion of the at least one optical fibre is disposed about a motor of the rotary equipment and covered with a shroud.

17. The method of claim 1 wherein the at least one optical fibre is a plurality of optical fibres.

18. The method of claim 1 wherein observing vibration created by the rotary equipment further includes detecting stall of the downhole motor and in response, reducing the weight on bit or lifting the elongate structure until the downhole motor restarts.

19. The method of claim 1 wherein observing vibration created by the rotary equipment includes transforming the time and location vibration data into frequency, location, and intensity data.

Assignees

• Schlumberger Technology Corp

Inventors

• Humphrey Caroline
• Johnson Ashley Bernard
• Dickenson Paul Frederick Cilgrim
• Tunc Gokturk
• Barrett Michael Paul

Classifications

• E21B17/206 Primary

  with conductors, e.g. electrical, optical · CPC title

• E21B47/135 Primary

  using light waves, e.g. infrared or ultraviolet waves · CPC title

• E21B47/13

  by electromagnetic energy, e.g. radio frequency · CPC title

• E21B47/007 Primary

  Measuring stresses in a pipe string or casing (for locating blocked portions of pipes E21B47/09) · CPC title

• G01L1/103

  optical excitation or measuring of vibrations · CPC title