SYSTEM AND METHOD FOR MEASURING DEPTH AND VELOCITY OF INSTRUMENTATION WITHIN A WELLBORE USING A BENDABLE TOOL

• US 20090084546A1
• Filed: 10/02/2007
• Published: 04/02/2009
• Est. Priority Date: 10/02/2007
• Status: Active Grant

• Current Assignee: Gyrodata Incorporated
• Original Assignee: Gyrodata Incorporated
• Inventors: Ekseth, Roger, Weston, John Lionel, Mullin, Stephen Victor
• Granted Patent: US 8,065,085 B2
• Time in Patent Office: Days
• US Class Current: 166/255.100
• CPC Class Codes: E21B 47/022 of the borehole, e.g. using geomagnetism
• CPC Class Codes: E21B 47/04 Measuring depth or liquid level
• CPC Class Codes: G01V 9/00 Prospecting or detecting by methods not provided for in groups G01V1/00 - G01V8/00
• CPC Class Codes: G06F 17/00 Digital computing or data processing equipment or methods, specially adapted for specific functions information retrieval, database structures or file system structures therefor G06F16/00

Abstract

An apparatus and method for measuring depth, velocity, or both depth and velocity of instrumentation within a wellbore is provided. The apparatus includes a downhole portion movable within the wellbore in a direction generally parallel to the wellbore. The apparatus further includes a first acceleration sensor mounted at a first position within the downhole portion. The first acceleration sensor generates a first signal indicative of a first acceleration in a first direction generally parallel to the wellbore at the first position. The apparatus further includes a second acceleration sensor mounted at a second position within the downhole portion. The second acceleration sensor generates a second signal indicative of a second acceleration in a second direction generally parallel to the wellbore at the second position. The apparatus further includes a bend sensor generating a third signal indicative of an amount of bend of at least a portion of the downhole portion.

Claims

1. An apparatus for use in a wellbore, the apparatus comprising:

a downhole portion movable within the wellbore in a direction generally parallel to the wellbore;

a first acceleration sensor mounted at a first position within the downhole portion, the first acceleration sensor generating a first signal indicative of a first acceleration in a first direction generally parallel to the wellbore at the first position;

a second acceleration sensor mounted at a second position within the downhole portion, the second acceleration sensor generating a second signal indicative of a second acceleration in a second direction generally parallel to the wellbore at the second position; and

a bend sensor generating a third signal indicative of an amount of bend of at least a portion of the downhole portion.

2. The apparatus of claim 1, wherein the apparatus is a drill string.

3. The apparatus of claim 1, wherein the apparatus is a measurement-while-drilling string.

4. The apparatus of claim 1, wherein the apparatus is a logging string.

5. The apparatus of claim 1, wherein the apparatus is a logging-while-drilling string.

6. The apparatus of claim 1, additionally comprising a controller to calculate a depth, a velocity, or both a depth and a velocity of the downhole portion in response to the first, second, and third signals.

7. The apparatus of claim 1, wherein the bend sensor comprises an optical system comprising a light source and a light detector separated from the light source by a non-zero distance along the wellbore, the light source configured to direct light towards the light detector, the light impinging upon a first portion of the light detector when the downhole portion is in an unbent state and upon a second portion of the light detector when the downhole portion is in a bent state.

8. The apparatus of claim 1, wherein the bend sensor comprises an optical system which uses interferometry to detect the amount of bend.

9. The apparatus of claim 1, wherein the bend sensor detects an amount of deflection of at least one part of the downhole portion relative to another part of the downhole portion.

10. The apparatus of claim 1, wherein the bend sensor detects an amount of mechanical strain in a part of the downhole portion due to the amount of bend.

11. The apparatus of claim 1, wherein the third signal is indicative of an amount of bend in each of two generally orthogonal planes.

12. The apparatus of claim 1, wherein the first direction differs by a non-zero angle relative to the second direction when the downhole portion is in a bent state.

13. The apparatus of claim 1, wherein measurements are taken by the first acceleration sensor, the second acceleration sensor, and the bend sensor simultaneously.

14. The apparatus of claim 1, wherein the first position is separated from the second position by a distance larger than approximately 10 meters.

15. The apparatus of claim 1, wherein the bend sensor is mounted at a third position within the downhole portion, the third position between the first and second positions.

16. The apparatus of claim 15, wherein the third position is located approximately equidistant from the first position and the second position.

17. A method for generating information indicative of a depth or a velocity, or both a depth and a velocity, of a downhole portion of a tool movable within a wellbore, the method comprising:

providing a tool comprising;

a downhole portion movable within the wellbore in a direction generally parallel to the wellbore;

a first acceleration sensor mounted at a first position within the downhole portion, the first acceleration sensor generating a first signal indicative of a first acceleration in a first direction generally parallel to the wellbore at the first position;

a second acceleration sensor mounted at a second position within the downhole portion, the second acceleration sensor generating a second signal indicative of a second acceleration in a second direction generally parallel to the wellbore at the second position; and

a bend sensor generating a third signal indicative of an amount of bend of at least a portion of the downhole portion;

generating the first signal, the second signal, and the third signal while the downhole portion is at a first location within the wellbore; and

generating the first signal, the second signal, and the third signal while the downhole portion is at a second location within the wellbore.

18. The method of claim 17, further comprising calculating a depth, or a velocity, or both a depth and a velocity, of the downhole portion of the tool in response to the first, second, and third signals generated while the downhole portion is at the first location and the first, second, and third signals generated while the downhole portion is at the second location.

19. The method of claim 18, wherein calculating a depth, or a velocity, or both a depth and a velocity, of the downhole portion of the survey tool comprises using a recursive algorithm.

20. The method of claim 19, wherein the recursive algorithm employs measurements obtained at multiple locations to update estimates of the depth, the velocity, or both the depth and the velocity of the downhole portion.

21. The method of claim 17, wherein the downhole portion is stationary while at the first location or at the second location.

22. The method of claim 17, wherein the downhole portion is moving while at the first location or at the second location.

23. A method for determining a depth or a velocity, or both a depth and a velocity, of a downhole portion of a tool movable within a wellbore, the method comprising:

receiving one or more acceleration measurements from at least one acceleration sensor in the downhole portion of the tool;

receiving one or more measurements of an amount of bend of at least a portion of the downhole portion; and

calculating a depth, or a velocity, or both a depth and a velocity, of the downhole portion of the tool in response to the one or more acceleration measurements and the one or more measurements of the amount of bend.

24. A bendable tool for use in a wellbore, the tool comprising:

a first acceleration sensor mounted within the tool, the first acceleration sensor configured to generate a first signal indicative of a first acceleration of the first acceleration sensor in a first direction generally parallel to the wellbore;

a second acceleration sensor mounted within the tool, the second acceleration sensor configured to generate a second signal indicative of a second acceleration of the second acceleration sensor in a second direction generally parallel to the wellbore; and

a bend sensor configured to generate a third signal indicative of an amount of bend of at least a portion of the tool between the first acceleration sensor and the second acceleration sensor.

25. A system for use with an apparatus configured to be inserted into a wellbore, the system comprising:

one or more inputs configured to receive a first signal from a first acceleration sensor of the apparatus, a second signal from a second acceleration sensor of the apparatus, and a third signal from a bend sensor of the apparatus, the first acceleration sensor within a downhole portion of the apparatus, the second acceleration sensor within the downhole portion of the apparatus and spaced from the first acceleration sensor generally along the wellbore, the first signal indicative of a first acceleration of the first acceleration sensor in a first direction generally parallel to the wellbore, the second signal indicative of a second acceleration of the second acceleration sensor in a second direction generally parallel to the wellbore, the third signal indicative of an amount of bend of at least a portion of the apparatus between the first acceleration sensor and the second acceleration sensor; and

a controller configured to calculate a depth, a velocity, or both a depth and a velocity of the downhole portion within the wellbore in response to the first signal, the second signal, and the third signal.