EP0339746A2 - Support en forme de corne de Wood pour un transducteur acoustique - Google Patents

Support en forme de corne de Wood pour un transducteur acoustique Download PDF

Info

Publication number
EP0339746A2
EP0339746A2 EP89201068A EP89201068A EP0339746A2 EP 0339746 A2 EP0339746 A2 EP 0339746A2 EP 89201068 A EP89201068 A EP 89201068A EP 89201068 A EP89201068 A EP 89201068A EP 0339746 A2 EP0339746 A2 EP 0339746A2
Authority
EP
European Patent Office
Prior art keywords
transducer
backing
sound
acoustical
attenuating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP89201068A
Other languages
German (de)
English (en)
Other versions
EP0339746A3 (fr
Inventor
Frederick Henry Kreisler Rambow
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shell Internationale Research Maatschappij BV
Original Assignee
Shell Internationale Research Maatschappij BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shell Internationale Research Maatschappij BV filed Critical Shell Internationale Research Maatschappij BV
Publication of EP0339746A2 publication Critical patent/EP0339746A2/fr
Publication of EP0339746A3 publication Critical patent/EP0339746A3/fr
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/002—Devices for damping, suppressing, obstructing or conducting sound in acoustic devices
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators

Definitions

  • the present invention relates to borehole logging technologies, and more particularly to an improved acoustical transducer configuration and method for borehole logging applications.
  • acoustical techniques include the Borehole Televiewer, the Pulse Echo Tool, and the Cement Evaluation Tool, for example.
  • an acoustic pulse is generated, injected or directed into the target of the survey (depending upon the tool involved), subsequently received, and then analyzed to determine the effects which the target environment had upon the pulse. The analysis is then interpreted to provide a description of that environment. The steps are repeated for thousands upon thousands of such pulses to generate a permanent record or log, typically as a function of depth within the borehole.
  • an ideal pulse would be one cycle or waveform long.
  • real world physical systems cannot be started and stopped quite so sharply.
  • a common problem is the "ring-down" of the transducer after the electrical impulse has been dis­continued. Being a physical system, the acoustical inertia of the transducer will cause it to oscillate for a short period there­after. This increases the pulse width, which not only makes analysis of the subsequently received returning acoustical signal more difficult, but can also reduce the repetition rate at which distinct pulses can be generated.
  • trans­ducer backing which appears to be acoustically infinitely deep, or in other words, which will return no energy to the back of the transducer.
  • the present invention provides an acoustical trans­ducer provided with a sound attenuating backing for decreasing the ring-down time of the transducer, comprising a tapered backing having a face portion and a wall portion said, face portion being acoustically coupled to the transducer, said backing having an acoustical impedance substantially the same as the transducer, and the taper of said backing terminating substantially in a line or point on the backing substantially opposite the face, and comprising sound absorbing means acoustically coupled to the wall portion of said backing.
  • said backing is formed of substantially the same material as the transducer, the backing and the transducer being both ceramic material, the transducer being a poled ceramic and said backing being an unpoled ceramic of the same type as the transducer.
  • said backing has the form of a wedge.
  • the wedge has the shape of a cone, the cone being curved and tapered in the shape of a Wood's Horn.
  • the sound absorbing means is advantageously a tungsten loaded rubber, the wall portion of the backing being embedded in the sound absorbing means.
  • the present invention provides a method for attenuating sound from the back of such a transducer for decreasing the ring-down time of the transducer, comprising the steps of: - absorbing substantially all the acoustic energy from the back of such an acoustical transducer in a tapered backing having a face portion and a wall portion, the face portion being acoustically coupled to the transducer, the backing having an acoustical impedance substantially the same as the transducer, and the taper of the backing terminating substantially in a line or point on the backing substantially opposite the face; and - attenuating the sound in the backing with a sound absorber acoustically coupled to the wall portion of the backing.
  • Wood's Horn type device has not heretofore been used in acoustics, historically it is known from and has been used in optics. Its function is to reduce extraneous reflections in an optical device by trapping, attenuating, and ultimately extinguishing any light which enters it.
  • the optical Wood's Horn is typically made of glass, coated on the inside with carbon black, and otherwise hollow.
  • the sound attenuating backing for borehole logging applications is significantly different in several respects. First, it is not hollow. Secondly, the sound absorption does not all take place at the back wall of the Wood's Horn backing.
  • the Horn is preferably embedded in tungsten loaded rubber sound absorbing material, and the Wood's Horn itself is either a solid or liquid of the desired shape located within the sound absorbing material.
  • transducer and said method are suited to the widest possible utilization in acoustical type borehole logging applications.
  • FIG. 1 shows, somewhat figuratively, a borehole televiewer 10 suspended in a borehole 14 penetrating earth formations 16.
  • a motor 17 within the televiewer 10 drives a shaft 18 which in turn rotates a cylindrical transducer assembly 20 located on the bottom of the borehole televiewer 10.
  • the transducer assembly 20 includes a transducer 25 to which thin front and rear metallic electrodes 26 and 27 are attached in conventional fashion.
  • the transducer is a 1.0 inch (2.5 cm) diameter, 1 megahertz transducer of poled lead metaniobate ceramic, available from Keramos, Inc., Indianapolis, Indiana under the name Kezite K-81 (registered trademark).
  • the transducer has a mechanical Q measured in the thickness mode which is less than 15.
  • a backing 30 shaped in the form of a Wood's Horn.
  • Backing 30 has a face 31 in contact with electrode 27 and a tapered, curvilinear wall portion 32 extending rearwardly from the face 31 and ultimately terminating in a point 33 sub­stantially opposite the face 31.
  • Transducer 25 and the backing wall 32 are, in turn, embedded in a rubber sound absorber 35.
  • Backing 30 is also made from Kezite K-81 ceramic but is unpoled (i.e., does not have piezoelectric properties).
  • the acoustic properties of the backing 30 and the transducer 25 are as closely matched as possible.
  • the Wood's Horn shape of the backing wall 32 reduces multiple scattering in the backing 30 as much as possible.
  • the rubber sound absorber 35 is a high temperature tungsten loaded rubber which also has an acoustical impedance nearly identical to that of the transducer 25 and backing 30, and further is highly attenuating to sound energy which passes into it.
  • a suitable such loaded rubber for absorber 35 may be, for example, any high temperature silicone elastomer.
  • the backing 30 and absorber 35 combination provides essentially no opportunity for acoustical energy coupled thereto from the transducer 25 to find its way back to the transducer. That is, since the impedances of the materials are matched, the interfaces between and among the several materials are almost invisible to the sound energy, so very little is reflected. What reflections do occur in the Wood's Horn backing 30 cause the sound energy to travel deeper into the Horn and not to return to the transducer 25. Energy which enters the absorber 35 is quickly damped. Thus maximum attenuation for the transducer is provided, substantially shortening the ring-down time character­istics thereof.
  • a Wood's Horn configuration for the backing is preferred, it will be immediately apparent that other variations on the invention will conceptually and physically provide remarkably improved attenuation.
  • a wedge-shaped backing is much easier and less expensive to fabricate than one shaped as a Wood's Horn.
  • the attenuating characteristics of a suitably shaped wedge are extremely favorable. Such a wedge would terminate in most cases in a line defined by the intersection of the major planar surfaces on the rear of the wedge-shaped backing.
  • the important concepts here are the absence of a rear surface area which might reflect acoustic energy directly back to the front face of the backing, and a small reflection angle that maximizes the number of reflections suffered by the acoustic beam within the wedge before it can return to the front face.
  • the phrase "terminating sub­stantially in a line or point" is to be taken to mean that there is not a surface, as such, where the backing terminates opposite the transducer.
  • Such a line may be straight or curved, and the term "point” would be taken to be the extreme situation of a line infinitely short.
  • Fig. 4 is an example of such a wedge 40 that is easy to machine, yet very efficient in reducing unwanted energy returned to the transducer.
  • the representative ray or beam path 45 experiences six reflections before being reversed at the seventh to return back to the face 31 -- a total of thirteen reflections in all.
  • the total energy returned assuming even a large reflection coefficient of 0.1 (i.e., a poor match between the wedge and the tungsten-rubber absorber in which it is embedded), will be reduced by a factor of 10 ⁇ 13.
  • beam spreading and beam front curvature will cause a fraction of the energy to turn back before seven reflections.
  • reflection coefficients lower than 0.1 can be achieved with the result that the reflected signal returning to the transducer is reduced several orders of magnitude.
  • a cone may be considered to be a special case of a wedge, and the Wood's Horn a special case of a cone, all terminating substantially in a line or point opposite the face of the backing at the transducer.
  • the present invention provides numerous advantages. Principally, it significantly shortens the ring-down time of a transducer utilized in borehole logging applications while maintaining a very good signal-to-noise ratio for the transducer. With the present invention, a short pulse length of only about 2 cycles can be achieved without reduction in the transducer signal-to-noise ratio.
  • the acoustically matched backing and absorber, and the special shape of the backing, while of convenient finite physical length, appear acoustically to be virtually infinitely deep, so that essentially none of the acoustic energy coupled thereto from the transducer returns to the transducer.
  • a further advantage of the matched backing is the much lower Q, hence increased bandwidth of a transducer so backed. That is, by exactly matching the backing impedance to the transducer the length of the transducer is effectively extended to infinity.
  • the transducer can then be electronically tuned to operate efficiently over a broad band of frequencies. In tests, for instance, a 1 MHz transducer mounted on such a wedge has been run between 1 MHz and about 200 kHz with no noticeable change in peak voltage of the detected signal.
  • the invention can be readily and easily incorporated into many different types of borehole logging tools, such as the borehole televiewer illustrated generally in Fig. 1, in which acoustical transducers are utilized in a pulsed mode.
  • the invention is fully functional in borehole environments, is inexpensive, uncomplicated, durable, versatile, relatively easy and inexpensive to manufacture and implement, and thus readily suited to the widest possible utilization in such borehole logging applications.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
  • Geophysics And Detection Of Objects (AREA)
  • Transducers For Ultrasonic Waves (AREA)
EP19890201068 1988-04-29 1989-04-25 Support en forme de corne de Wood pour un transducteur acoustique Withdrawn EP0339746A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US18775488A 1988-04-29 1988-04-29
US187754 1988-04-29

Publications (2)

Publication Number Publication Date
EP0339746A2 true EP0339746A2 (fr) 1989-11-02
EP0339746A3 EP0339746A3 (fr) 1991-07-03

Family

ID=22690329

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890201068 Withdrawn EP0339746A3 (fr) 1988-04-29 1989-04-25 Support en forme de corne de Wood pour un transducteur acoustique

Country Status (2)

Country Link
EP (1) EP0339746A3 (fr)
NO (1) NO891761L (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2743653A1 (fr) * 2012-12-13 2014-06-18 Sick Ag Transducteur ultrasonore et procédé d'excitation et/ou de détection de signaux utrasoniques
WO2016108841A1 (fr) * 2014-12-30 2016-07-07 Halliburton Energy Services, Inc. Transducteurs acoustiques ajustables pour un outil de fond de trou
WO2024076351A1 (fr) * 2022-10-07 2024-04-11 Halliburton Energy Services, Inc. Support de coupe en coin de transducteur acoustique pour une meilleure atténuation

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB705080A (en) * 1951-06-06 1954-03-10 Marconi Wireless Telegraph Co Improvements in or relating to ultra-sonic wave absorption apparatus
GB869582A (en) * 1957-08-19 1961-05-31 Chirana Praha Mechanical damping member for an electroacoustic transducer
US3403271A (en) * 1966-02-09 1968-09-24 Hewlett Packard Co Ultrasonic transducer with absorptive load

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB705080A (en) * 1951-06-06 1954-03-10 Marconi Wireless Telegraph Co Improvements in or relating to ultra-sonic wave absorption apparatus
GB869582A (en) * 1957-08-19 1961-05-31 Chirana Praha Mechanical damping member for an electroacoustic transducer
US3403271A (en) * 1966-02-09 1968-09-24 Hewlett Packard Co Ultrasonic transducer with absorptive load

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
IEEE TRANS. ON SONICS AND ULTRASONICS, vol. SU-26, no. 2, March 1979, pages 140-142, New York, US; R.G. SWARTZ et al.: "An improved wedge-type backing for piezoelectric transducers" *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2743653A1 (fr) * 2012-12-13 2014-06-18 Sick Ag Transducteur ultrasonore et procédé d'excitation et/ou de détection de signaux utrasoniques
CN103868556A (zh) * 2012-12-13 2014-06-18 西克股份公司 超声波换能器和用于产生和/或吸收超声波的方法
WO2016108841A1 (fr) * 2014-12-30 2016-07-07 Halliburton Energy Services, Inc. Transducteurs acoustiques ajustables pour un outil de fond de trou
GB2547810A (en) * 2014-12-30 2017-08-30 Halliburton Energy Services Inc Adjustable acoustic transducers for a downhole tool
AU2014415593B2 (en) * 2014-12-30 2018-04-12 Halliburton Energy Services, Inc. Adjustable acoustic transducers for a downhole tool
US10443375B2 (en) 2014-12-30 2019-10-15 Halliburton Energy Services, Inc. Adjustable acoustic transducers for a downhole tool
WO2024076351A1 (fr) * 2022-10-07 2024-04-11 Halliburton Energy Services, Inc. Support de coupe en coin de transducteur acoustique pour une meilleure atténuation
US20240118446A1 (en) * 2022-10-07 2024-04-11 Halliburton Energy Services, Inc. Wedge-Cut Backing Of Acoustic Transducer For Improved Attenuation

Also Published As

Publication number Publication date
EP0339746A3 (fr) 1991-07-03
NO891761L (no) 1989-10-30
NO891761D0 (no) 1989-04-27

Similar Documents

Publication Publication Date Title
US6940420B2 (en) Drill string telemetry system
KR100732831B1 (ko) 초음파송수파기
US4382290A (en) Apparatus for acoustically investigating a borehole
US4649525A (en) Shear wave acoustic logging system
US3794866A (en) Ultrasonic search unit construction
EP0116244A1 (fr) Méthode et appareillage de détection des fractures par échographie ultrasonique le long de la paroi d'un matériau ou d'une formation
US5146050A (en) Method and apparatus for acoustic formation dip logging
JPH0477275B2 (fr)
Lane Absorption mechanisms for waterborne sound in Alberich anechoic layers
WO1993011528A1 (fr) Controle acoustique non destructif
Lafleur et al. Acoustically active surfaces using piezorubber
US5088327A (en) Phase cancellation enhancement of ultrasonic evaluation of metal-to-elastomer bonding
EP0339746A2 (fr) Support en forme de corne de Wood pour un transducteur acoustique
JP3672565B2 (ja) 小断面脈管超音波像形成トランスジューサ
US3051927A (en) Transducer assemblies
CN206020343U (zh) 超声波探头锣型晶片及使用超声波探头锣型晶片的探头
US4312052A (en) Method for identifying weak sands
WO2006017168A2 (fr) Appareil et procede permettant d'emettre et de recevoir l'energie d'ondes acoustiques
RU1793367C (ru) Пьезоэлектрический преобразователь
DE3401979A1 (de) Ultraschall-wandler
RU1772724C (ru) Пьезоэлектрический преобразователь
Zhu et al. Tool Wave in Acoustic Logging While Drilling
JP7429008B2 (ja) 粗い内部構造を有する対象物の計測用音波送受波器
SU1188646A1 (ru) Акустический зонд
CA1199718A (fr) Systeme de diagraphie acoustique par ondes de cisaillement

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE FR GB NL

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE FR GB NL

17P Request for examination filed

Effective date: 19911206

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19931103