EP0218328A2
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EP
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Methods of analyzing vibrations from a drilling bit in a borehole
Assignee: Services Petroliers Schlumberger SA
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Filing: 1986-08-07
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Granted: —
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Expires: 2006-08-07
Abstract
Abstract Information on tooth wear is obtained from the frequency distribution spectrum of a vibrational quantity influenced by the impact of cutter teeth on the bottom of a bore. In the illustrated example spectra are obtained from the product of torque and torsional acceleration and tooth wear is indicated by the shift upwardly in frequency of a pronounced peak occurring at T1 for a one eighth worn bit and at T5 for a five eighths worn bit. Other quantities which may be used, singly or together to enhance spectral information, are weight on bit, vertical acceleration, transverse acceleration, standpipe pressure. Abrupt changes in frequency distribution curves indicate abrupt occurrences such as broken teeth or stuck cones. A stuck cone is also indicated by unidirectional peaks in a plot of torsional acceleration against time.
Inventors
- 👤 Marc Lesage
- 👤 Michael Sheppard
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 20:28
CPC Classifications
E; E21; E21B; E21B49/00; E21B49/003; E21B12/00; E21B12/02; E21B44/00
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
53 words
A method of analysing the vibrations from a drilling bit in a borehole wherein an oscillatory signal is derived from one or more transducers sensing physical quantities associated with the bit, a frequency spectrum is derived from the oscillatory signal and the frequency spectrum is monitored to detect gradual or abrupt changes therein.
Claim 2
Independent Claim
53 words
A method of analysing the vibrations from a drilling bit in a borehole wherein an oscillatory signal is derived from one or more transducers sensing physical quantities associated with the bit, a frequency spectrum is derived from the oscillatory signal and the frequency spectrum is monitored to detect gradual or abrupt changes therein.
Claim 3
Dependent Claim
19 words
A method according to claim 1 wherein the frequency spectrum is normalized relative to the rate of bit rotation.
Claim 4
Dependent Claim
24 words
A method according to claim 1 or 2, wherein the oscillatory signal is formed from the product of signals from a plurality of transducers.
Claim 5
Dependent Claim
31 words
A method according claim 1, 2, or 3, wherein the transducer(s) sense one or more of weight on bit, torque, torsional acceleration vertical acceleration, transverse acceleration or stress and standpipe pressure.
Claim 6
Independent Claim
32 words
A method according to any of claims 1 to 4 wherein the signal from the or each transducer within a sampling interval is averaged or integrated over a succession of sampling intervals.
Claim 7
Dependent Claim
30 words
A method according to claim 5, wherein each signal is held as a plurality of digital samples and the frequency spectrum is obtained by means of a digital Fourier transform.
Claim 8
Independent Claim
28 words
A method according to any of claims 1 to 6, wherein shift of a peak or peaks in the frequency spectrum is detected to detect bit tooth wear.
Claim 9
Independent Claim
32 words
A method according to any of claims 1 to 7, wherein appearance or disappearance of peaks in the frequency spectrum is detected to detect loss of teeth or a stuck bit wheel.
Claim 10
Independent Claim
25 words
A method according to any of claims 1 to 8, wherein change in amplitude of one or more peaks is detected to indicate rock hardness.
Claim 11
Dependent Claim
28 words
A method according to claim 9, wherein indicated rock hardness is correlated with rate of penetration, weight on bit or torque to provide an indication of drilling conditions.
Claim 12
Independent Claim
21 words
A method according to claim g or 10, wherein the change of amplitude is detected in the frequency spectrum of torque.
Claim 13
Independent Claim
32 words
A method according to any of claims 1 to 12, wherein changes of peak amplitudes in the frequency spectrum of weight on bit are detected to detect a bit with bad cleaning.
Claim 14
Independent Claim
44 words
A method of analysing the vibrations from a drilling bit in a borehole wherein oscillatory signals are derived from a plurality of transducers sensing physical quantities associated with the bit, and the signals are correlated or compared to enhance the information obtained by analysis.
Claim 15
Independent Claim
44 words
A method of analysing the vibrations from a drilling bit in a borehole wherein oscillatory signals are derived from a plurality of transducers sensing physical quantities associated with the bit, and the signals are correlated or compared to enhance the information obtained by analysis.
Claim 16
Dependent Claim
20 words
A method according to claim 13 characterised in that signals are multiplied together to enhance features common to the signals.
Claim 17
Independent Claim
50 words
A method of analysing the vibrations from a drilling bit in a borehole wherein oscillatory signals are derived from a plurality of transducers sensing physical quantities associated with the bit, characterised in that unidirectional peaks in the torsional acceleration of the bit are detected to identify a stuck bit cutter.
Claim 18
Independent Claim
50 words
A method of analysing the vibrations from a drilling bit in a borehole wherein oscillatory signals are derived from a plurality of transducers sensing physical quantities associated with the bit, characterised in that unidirectional peaks in the torsional acceleration of the bit are detected to identify a stuck bit cutter.
References Cited (Backward Citations)
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