Patent US3697937A successfully refreshed from Google Patents.
US3697937A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic reflection coefficient logging
Assignee: Schlumberger Technology Corp
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Filing: 1969-07-09
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Granted: 1972-10-10
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Expires: 1989-07-09
Abstract
Abstract An illustrative embodiment of the present invention includes method and apparatus for performing acoustic reflection coefficient logging in a well borehole. An acoustic well logging tool having at least a pair of biradially mounted receivers disposed in a zero spacing configuration and each comprising a plurality of arcuate segments disposed in a one-to-one relationship with each other is moved through the well bore. The electrical outputs of corresponding receiver segment pairs are processed to extract their relative amplitude and phase at a plurality of frequencies over the acoustic spectrum. The amplitude and phase data are used to compute the acoustic reflection coefficient exactly at the said plurality of frequencies over the acoustic spectrum thereby providing a frequency spectrum of acoustic reflection coefficients as measured at each of the paired biradially mounted receiver segments at each borehole depth. Such acoustic reflection coefficient spectra may be utilized, among other things, for evaluating cement conditions in the well bore.
Inventors
- 👤 John D Ingram
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:37
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/40; G01V1/44
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
176 words
A method of acoustically logging a well bore to provide a frequency spectrum of the acoustic reflection coefficient comprising the steps of: transmitting a component of acoustic energy radially outwardly from the borehole into the cement and surrounding formations; receiving a reflected portion of the transmitted acoustic energy at two different radii in the borehole and generating first and second electrical signals representative thereof; passing said first and second signals through n, where n is an integer number, relatively narrow bandpass filters having different center frequencies spaced over the acoustic spectrum to provide n pairs of corresponding frequency components for said first and second signals; generating third electrical signals representative of the relative phase of each of said n pairs of corresponding frequency components; generating fourth electrical signals representative of the relative amplitudes of each of said n pairs of corresponding frequency components; and combining said third and fourth signals to generate n signals representative of the acoustic reflection coefficient for each of the n frequency components, thereby providing a frequency spectrum of acoustic reflection coefficients.
Claim 2
Independent Claim
176 words
A method of acoustically logging a well bore to provide a frequency spectrum of the acoustic reflection coefficient comprising the steps of: transmitting a component of acoustic energy radially outwardly from the borehole into the cement and surrounding formations; receiving a reflected portion of the transmitted acoustic energy at two different radii in the borehole and generating first and second electrical signals representative thereof; passing said first and second signals through n, where n is an integer number, relatively narrow bandpass filters having different center frequencies spaced over the acoustic spectrum to provide n pairs of corresponding frequency components for said first and second signals; generating third electrical signals representative of the relative phase of each of said n pairs of corresponding frequency components; generating fourth electrical signals representative of the relative amplitudes of each of said n pairs of corresponding frequency components; and combining said third and fourth signals to generate n signals representative of the acoustic reflection coefficient for each of the n frequency components, thereby providing a frequency spectrum of acoustic reflection coefficients.
Claim 3
Dependent Claim
28 words
The method of claim 1 and further including the step of recording said n signals representative of the acoustic reflection coefficient for each of the n frequency components.
Claim 4
Dependent Claim
45 words
The method of claim 1 wherein the steps are performed periodically while moving a logging tool vertically through the well bore and the frequency spectrum of acoustic reflection coefficients is recorded as a function of borehole depth at each level traversed by the logging tool.
Claim 5
Independent Claim
264 words
A method of acoustically logging a well bore to provide a frequency spectrum of the acoustic reflection coefficient comprising the steps of: transmitting a component of acoustic energy radially outwardly from the borehole into the cement and surrounding formations; receiving a reflected portion of the transmitted acoustic energy at a pair of biradially mounted acoustic receivers, each having l angular segments, where l is an integer number 2 or greater, and generating l pairs of electrical signals representative of the received acoustic energy at each corresponding pair of receiver segments; passing each of said l pairs of corresponding signals through n, where n is an integer number, relatively narrow bandpass filters having different center frequencies spaced over the acoustic spectrum to provide n pairs of corresponding frequency components for each of the l corresponding receiver segment pairs; generating electrical signals representative of the relative phase of each of said n pairs of corresponding frequency components for each of said l corresponding receiver segment pairs; generating electrical signals representative of the relative amplitudes of each of said n pairs of corresponding frequency components for each of said l corresponding receiver segment pairs; and combining said relative phase and relative amplitude signals for each of said n pairs of corresponding frequency components for each of said l corresponding receiver segment pairs to generate n signals representative of the acoustic reflection coefficient for each of the n frequency components thereby providing l frequency spectra of acoustic reflection coefficients corresponding to the reflection coefficient spectrum of each of the l angular segments of the biradially mounted acoustic receivers.
Claim 6
Independent Claim
264 words
A method of acoustically logging a well bore to provide a frequency spectrum of the acoustic reflection coefficient comprising the steps of: transmitting a component of acoustic energy radially outwardly from the borehole into the cement and surrounding formations; receiving a reflected portion of the transmitted acoustic energy at a pair of biradially mounted acoustic receivers, each having l angular segments, where l is an integer number 2 or greater, and generating l pairs of electrical signals representative of the received acoustic energy at each corresponding pair of receiver segments; passing each of said l pairs of corresponding signals through n, where n is an integer number, relatively narrow bandpass filters having different center frequencies spaced over the acoustic spectrum to provide n pairs of corresponding frequency components for each of the l corresponding receiver segment pairs; generating electrical signals representative of the relative phase of each of said n pairs of corresponding frequency components for each of said l corresponding receiver segment pairs; generating electrical signals representative of the relative amplitudes of each of said n pairs of corresponding frequency components for each of said l corresponding receiver segment pairs; and combining said relative phase and relative amplitude signals for each of said n pairs of corresponding frequency components for each of said l corresponding receiver segment pairs to generate n signals representative of the acoustic reflection coefficient for each of the n frequency components thereby providing l frequency spectra of acoustic reflection coefficients corresponding to the reflection coefficient spectrum of each of the l angular segments of the biradially mounted acoustic receivers.
Claim 7
Dependent Claim
61 words
The method of claim 4 and further including the step of recording said n signals representative of the acoustic reflection coefficients for each of the n frequency components and so doing for each of the l frequency spectra of acoustic reflection coefficients corresponding to the Reflection coefficient spectrum of each of the l angular segments of the biradially mounted acoustic receivers.
Claim 8
Dependent Claim
46 words
The method of claim 4 wherein the steps are performed periodically while moving a logging tool through the well bore and the resulting l frequency spectra of acoustic reflection coefficients are recorded as a function of borehole depth at each level traversed by the logging tool.
Claim 9
Independent Claim
228 words
A method for acoustically logging a cased borehole to determine the effectiveness of the cement disposed in the annulus between the casing and the formations comprising the steps of: moving an acoustic well logging tool having at least one acoustic transmitter and at least two acoustic receivers of different radii through the well bore; periodically firing said acoustic transmitter to propagate a component of acoustic energy radially outwardly from the borehole into the cement and surrounding formations; periodically activating said acoustic receivers in response to said transmitter firing to receive a reflected portion of the transmitted acoustic energy at, at least two different radii in the borehole and generating a plurality of electrical signals representative of said reflected portion of acoustic energy; separating each of said representative electrical signals into a plurality of signals representative of discrete frequency components, the frequency components of each representative signal being in a one-to-one correspondence with each other; generating electrical signals representative of the relative phases of corresponding pairs of said frequency component signals; generating electrical signals representative of the relative amplitudes of corresponding pairs of said frequency component signals; and combining said relative phase signals and said relative amplitude signals for each of the corresponding pairs of said frequency component signals to generate signals representative of the acoustic reflection coefficient in the frequency region of each of said discrete frequency components.
Claim 10
Independent Claim
228 words
A method for acoustically logging a cased borehole to determine the effectiveness of the cement disposed in the annulus between the casing and the formations comprising the steps of: moving an acoustic well logging tool having at least one acoustic transmitter and at least two acoustic receivers of different radii through the well bore; periodically firing said acoustic transmitter to propagate a component of acoustic energy radially outwardly from the borehole into the cement and surrounding formations; periodically activating said acoustic receivers in response to said transmitter firing to receive a reflected portion of the transmitted acoustic energy at, at least two different radii in the borehole and generating a plurality of electrical signals representative of said reflected portion of acoustic energy; separating each of said representative electrical signals into a plurality of signals representative of discrete frequency components, the frequency components of each representative signal being in a one-to-one correspondence with each other; generating electrical signals representative of the relative phases of corresponding pairs of said frequency component signals; generating electrical signals representative of the relative amplitudes of corresponding pairs of said frequency component signals; and combining said relative phase signals and said relative amplitude signals for each of the corresponding pairs of said frequency component signals to generate signals representative of the acoustic reflection coefficient in the frequency region of each of said discrete frequency components.
Claim 11
Dependent Claim
42 words
The method of claim 7 and further including the step of recording as a function of the borehole depth of said logging tool, said signals representative of the acoustic reflection coefficient in the frequency region of each of said discrete frequency components.
Claim 12
Dependent Claim
58 words
The method of claim 7 wherein the step of breaking each of said representative electrical signals down into a plurality of signals representative of discrete frequency components is performed by applying each of said representative signals to a plurality of relatively narrow bandpass frequency filters having different center frequencies disposed over a selected portion of the acoustic spectrum.
Claim 13
Dependent Claim
80 words
The method of claim 7 wherein said acoustic receivers are angularly segmented and have receiver segment pairs in one to one correspondence with each other, each corresponding receiver segment pair disposed adjacent the same angular arc of the borehole and the remaining method steps pertaining to the signal processing are each performed on the representative signals generated by each corresponding receiver segment pair, thereby providing an independent frequency spectrum of acoustic reflection coefficients for each angular arc of the borehole.
Claim 14
Dependent Claim
65 words
The method of claim 7 and further including the step of correcting said signals representative of discrete frequency components of the representative signals for any amplitude distortion introduced by the frequency response of the acoustic receivers by amplifying each signal representative of a discrete frequency component by an amount inversely proportional to the sensitivity of the acoustic receiver in the frequency region said signal represents.
Claim 15
Independent Claim
138 words
A method of acoustically logging a cased borehole with a longitudinally extending exploring device to provide a plurality of frequency spectra of acoustic reflection coefficients comprising the steps of: transmitting a component of acoustic energy radially outwardly frOm the exploring device into the cement and surrounding formations; receiving a reflected portion of the transmitted acoustic energy at two different positions within the borehole which are at two positions having different radii relative to the central axis of the exploring device and generating first and second electrical signals representative thereof; separating said first and second signals into a plurality of corresponding pairs of frequency component signals; and determining from said plurality of corresponding pairs of frequency component signals, the plurality of acoustic reflection coefficients corresponding to each of the pairs of frequency component signals, and generating signals representative thereof.
Claim 16
Independent Claim
138 words
A method of acoustically logging a cased borehole with a longitudinally extending exploring device to provide a plurality of frequency spectra of acoustic reflection coefficients comprising the steps of: transmitting a component of acoustic energy radially outwardly frOm the exploring device into the cement and surrounding formations; receiving a reflected portion of the transmitted acoustic energy at two different positions within the borehole which are at two positions having different radii relative to the central axis of the exploring device and generating first and second electrical signals representative thereof; separating said first and second signals into a plurality of corresponding pairs of frequency component signals; and determining from said plurality of corresponding pairs of frequency component signals, the plurality of acoustic reflection coefficients corresponding to each of the pairs of frequency component signals, and generating signals representative thereof.
Claim 17
Dependent Claim
29 words
The method of claim 12 and further including the step of recording said plurality signals representative of the acoustic reflection coefficient corresponding to each of the frequency component signals.
Claim 18
Dependent Claim
31 words
The method of claim 12 wherein the steps are performed periodically as a well tool is moved through the borehole and the signals are recorded as a function of borehole depth.
Claim 19
Dependent Claim
198 words
Apparatus for acoustically logging a cased well bore to provide an acoustic reflection coefficient spectrum comprising: an acoustic well logging tool having at least one acoustic transmitter and at least two acoustic receivers of different radii; means for periodically firing said transmitter to propagate a component of acoustic energy radially outwardly from the borehole into the cement and surrounding formations; means for periodically activating said acoustic receivers in response to said transmitter firings to receive a reflected portion of the transmitted energy at said different radii and to generate a plurality of electrical signals representative thereof; means for separating said plurality of representative electrical signals into a plurality of signals representative of discrete frequency components of said signals, said frequency components being in a one-to-one correspondence with each other; means for generating electrical signals representative of the relative phases of corresponding pairs of said frequency component signals; means for generating electrical signals representative of the relative amplitudes of corresponding pairs of said frequency component signals; and means for combining said relative phase signals and said relative amplitude signals to generate signals representative of the acoustic reflection coefficient in the frequency region of each of said discrete frequency components.
Claim 20
Dependent Claim
198 words
Apparatus for acoustically logging a cased well bore to provide an acoustic reflection coefficient spectrum comprising: an acoustic well logging tool having at least one acoustic transmitter and at least two acoustic receivers of different radii; means for periodically firing said transmitter to propagate a component of acoustic energy radially outwardly from the borehole into the cement and surrounding formations; means for periodically activating said acoustic receivers in response to said transmitter firings to receive a reflected portion of the transmitted energy at said different radii and to generate a plurality of electrical signals representative thereof; means for separating said plurality of representative electrical signals into a plurality of signals representative of discrete frequency components of said signals, said frequency components being in a one-to-one correspondence with each other; means for generating electrical signals representative of the relative phases of corresponding pairs of said frequency component signals; means for generating electrical signals representative of the relative amplitudes of corresponding pairs of said frequency component signals; and means for combining said relative phase signals and said relative amplitude signals to generate signals representative of the acoustic reflection coefficient in the frequency region of each of said discrete frequency components.
Claim 21
Dependent Claim
44 words
The apparatus of claim 15 wherein said means for separating said plurality of representative electrical signals into signals representative of discrete frequency components includes a plurality of relatively narrow bandpass filters having different center frequencies disposed over a selected portion of the acoustic spectrum.
Claim 22
Dependent Claim
52 words
The apparatus of claim 15 wherein said means for generating signals representative of the relative phases of corresponding pairs of said frequency component signals includes phase comparator means for comparing the phases of said signals and means for generating an output signal representative of the difference of the phases of said signals.
Claim 23
Dependent Claim
49 words
The apparatus of claim 15 wherein said means for generating electrical signals representative of the relative amplitudes of corresponding pairs of said frequency component signals includes means for comparing the ratio of the amplitudes of said signals and means for generating an output signal representative of said amplitude ratio.
Claim 24
Dependent Claim
61 words
The apparatus of claim 15 wherein said means for combining said relative phase and said relative amplitude signals includes means for combining a signal representative of the difference of the phases of said signals and the ratio of said amplitudes, together with means for generating signals representative of the acoustic reflection coefficient derived from the phase difference and amplitude ratio siGnals.
Claim 25
Dependent Claim
91 words
Acoustic apparatus for logging a well bore to provide acoustic reflection coefficient logs of the well bore comprising: acoustic transmitting transducer means; first piezoelectric acoustic receiver means of a hollow cylindrical shape having a radius r1; second piezoelectric acoustic receiver means of a hollow cylindrical shape having a radius r2 different from r1 and electrically distinct from said first acoustic receiver; and means adapted for repetitively energizing said transmitting transducer means and producing separate electrical signals from said first and second receiver means for use in producing acoustic reflection coefficient logs.
Claim 26
Dependent Claim
91 words
Acoustic apparatus for logging a well bore to provide acoustic reflection coefficient logs of the well bore comprising: acoustic transmitting transducer means; first piezoelectric acoustic receiver means of a hollow cylindrical shape having a radius r1; second piezoelectric acoustic receiver means of a hollow cylindrical shape having a radius r2 different from r1 and electrically distinct from said first acoustic receiver; and means adapted for repetitively energizing said transmitting transducer means and producing separate electrical signals from said first and second receiver means for use in producing acoustic reflection coefficient logs.
Claim 27
Dependent Claim
25 words
The apparatus of claim 20 wherein both of said acoustic receiver means are mounted on the exterior surface of plural cylinders of acoustic absorbent material.
Claim 28
Dependent Claim
55 words
The apparatus of claim 21 wherein both of said acoustic receiver means are divided into n, where n is an integer number 2 or greater, corresponding angular segments, whereby each of the n corresponding receiver segment pairs receive reflected acoustic energy from the angular portion of the borehole in front of the receiver segment pairs.
Claim 29
Dependent Claim
34 words
The apparatus of claim 20 wherein said first and second receiver means are disposed along the longitudinal axis of the transducer array on either side of the transmitting transducer in a zero spacing arrangement.
Claim 30
Dependent Claim
128 words
Apparatus for acoustically logging a cased well borehole to determine the effectiveness of cement disposed in the annulus between the casing and the formation comprising: means for transmitting a component of acoustic energy radially outwardly from the borehole into the cement and surrounding formations; means for receiving a reflected portion of the transmitted acoustic energy at two different radial positions in the borehole and generating electrical signals representative thereof; means for performing a Fourier analysis of said first and second electrical signals to separate said signals into a plurality of corresponding pairs of frequency component signals; and means responsive to said plurality of corresponding pairs of frequency component signals for determining the plurality of acoustic reflection coefficients corresponding to said frequency component signals and generating signals representative thereof.
Claim 31
Dependent Claim
128 words
Apparatus for acoustically logging a cased well borehole to determine the effectiveness of cement disposed in the annulus between the casing and the formation comprising: means for transmitting a component of acoustic energy radially outwardly from the borehole into the cement and surrounding formations; means for receiving a reflected portion of the transmitted acoustic energy at two different radial positions in the borehole and generating electrical signals representative thereof; means for performing a Fourier analysis of said first and second electrical signals to separate said signals into a plurality of corresponding pairs of frequency component signals; and means responsive to said plurality of corresponding pairs of frequency component signals for determining the plurality of acoustic reflection coefficients corresponding to said frequency component signals and generating signals representative thereof.
Claim 32
Dependent Claim
33 words
The apparatus of claim 24 and further including means for recording as a function of borehole depth said signals representative of the acoustic reflection coefficients corresponding to said pairs of frequency component signals.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-10 | 1976-04-10 | 1976-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-10 | 1980-04-10 | 1980-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-10 | 1984-04-10 | 1984-10-10 | $7700.00 | Window Closed / Lapsed |