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JP2005223925

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DESCRIPTION JP2005223925
PROBLEM TO BE SOLVED: To provide an improved acoustic source and sensor for subsurface
applications. An acoustic transducer configured with integrated electronics technology is adapted
to digitize signal data near the transducer. The transducers are packaged with a reduced number
of elements and sealed for exposure to harsh environments without oil correction. The
transducer assembly includes a frame, an acoustic transducer element disposed on the frame,
and an electronics module disposed on the frame and connected to the acoustic transducer
element. The pressure and heat resistant electronics module is adapted to process signals
associated with the transducer elements. [Selected figure] Figure 22
Integrated acoustic transducer assembly
[0001]
RELATED APPLICATIONS The present invention is directed to U.S. Provisional Patent Application
Serial No. 60 / 535,062 filed January 8, 2004 and U.S. Provisional Patent Application Serial
Number 60 / 534,900 filed January 8, 2004. It claims priority in accordance with 35 USC
35,119. The present invention relates generally to acoustic transducers. More specifically, the
present invention relates to improved acoustic sources and sensors for subsurface applications.
[0002]
In the oil and gas industry, exploration of subsurface formations is generally performed by
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borehole logging equipment to determine formation characteristics. Of these instruments, it has
been found that sonic tools provide valuable information about subsurface acoustic
characteristics that can be used to generate images of formations or derive related
characteristics. Sound waves are periodic vibrational disturbances that result from acoustic
energy propagating through media such as subsurface formations. Sound waves are generally
characterized in terms of their frequency, amplitude, propagation velocity. The acoustic
properties associated with the formation can include compression wave velocity, shear wave
velocity, borehole mode, and formation retardation. In addition, acoustic images can be used to
show the condition of the borehole wall and other geological features at a distance from the
borehole. These acoustic measurements have applications in seismic correlation, oil reservoir
rock physics, rock mechanics, and other fields.
[0003]
Recording acoustic properties as a function of depth is known as acoustic logging. Information
obtained from sonic logging can be used for correlation between wells, determination of porosity,
determination of mechanical or elastic rock parameters to indicate rock quality, detection of
overpressured formation zones, measurement of the velocity of sound in formations. It may be
useful in a variety of applications including conversion of seismic time traces based on depth to
depth traces. Sonic logging of the Earth's formation involves unloading a sonic logging device or
tool into a borehole that traverses the formation. The apparatus generally comprises one or more
sound sources (ie, transmitters) for emitting acoustic energy to the subsurface formations, and
one or more acoustic sensors for receiving the acoustic energy or Includes a receiver. The
transmitter is actuated periodically to emit a pulse of acoustic energy into the borehole, the pulse
travels through the borehole and enters the formation. After propagating through the borehole
and formation, a portion of the acoustic energy is transmitted to the receiver where it is detected.
Various attributes of the detected acoustic energy are then associated with the relevant
subsurface or tool characteristics.
[0004]
FIG. 1 shows a conventional downhole sonic tool. The tool 10 is shown disposed in a borehole 12
which traverses the earth formation 20. The borehole 12 is generally filled with drilling fluid
(drilling fluid) used during borehole drilling. The tool 10 is usually implemented with a scissorlike support 13 which, in the case of a drill collar, allows the drilling fluid 14 to be the mud
motor and / or the bottom of the drilling string (not shown) as known in the art. Or includes an
internal passage 13A for reaching the drill bit. The logging tool 10 includes one or more acoustic
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transmitters 16 and a plurality of acoustic receivers 18 disposed on the cage 13. The receivers
18 are shown spaced from one another at a selected distance h along the longitudinal axis of the
tool 10. One of the receivers 18 closest to the transmitter 16 is axially spaced from the
transmitter a selected distance a. Tool 10 also houses one or more conventional computer
modules 21 including a microprocessor, memory, and software for processing waveform signal
data as known in the art. As also known in the art, the computer module 21 can be located in the
apparatus or on the surface or can be combined between the two as shown in FIG. The acoustic
energy wave 22 is shown propagating through the borehole. Conventional acoustic downhole
tools are disclosed in U.S. Patent Nos. 5,852,587, 4,543,648, 5,510,582, 4,594,691, 5,594,706,
Nos. 6,082,484, 6,631,327, 6,474,439, 6,494,288, 5,796,677, 5,309,404, 5 , 521, 882, 5, 753,
812, RE 34, 975, and 6, 466, 513.
[0005]
Conventional acoustic tools are equipped with acoustic transducer elements, such as
piezoelectric elements. In general, acoustic transducers convert energy between electrical and
acoustic forms and can be adapted to act as an acoustic source or sensor. Acoustic transducers
are generally attached to the body of a logging tool as shown in FIG. Conventional sound wave
sources and sensors used in downhole tools are described in U.S. Patent Nos. 6,466,513,
5,852,587, 5,886,303, 5,796,677, Nos. 5,469,736 and 6,084,826. For a variety of reasons,
including space constraints, these transducers generally package together multiple components
and mount them on the tool, and front-end electronics and circuitry remote from the transducer
elements Be placed.
[0006]
Acoustic transducer elements are also incorporated into configurations using printed circuit
boards (PCBs). U.S. Patent No. 6,501,211 describes an ultrasonic transducer implemented on a
PCB for attachment to a bolt head. The proposed converter is coupled to the remote computer to
perform bolt identification using the converter. U.S. Pat. No. 4,525,644 describes a mechanism
using a piezoelectric element located next to a PCB connection pad to increase the engagement
between the connection pad and the connector. EP 1467060 A1 describes a flexing piezoelectric
transducer for telemetric measurement of an acoustic signal through this tool in conjunction with
a downhole tool. The disadvantages of these conventional acoustic transducer systems include
insensitivity and the need for large electronics packages (e.g., large preamplifier stages) located
elsewhere.
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[0007]
U.S. Provisional Application No. 60 / 535,062 U.S. Provisional Application No. 60 / 534,900 U.S.
Pat. No. 5,852,587 U.S. Pat. No. 4,543,648 U.S. Pat. No. 5,510 U.S. Pat. No. 5,594,691 U.S. Pat.
No. 5,594,706 U.S. Pat. No. 6,082,484 U.S. Pat. No. 6,631,327 U.S. Pat. No. 6,474,439 U.S. Pat.
No. 6,494,288 U.S. Patent No. 5,796,677 U.S. Patent No. 5,309,404 U.S. Patent No. 5,521,882
U.S. Patent No. 5,753,812 U.S. Patent No. RE 34,975 U.S. Patent No. 6,466,513 U.S. Patent No.
5,886,303 U.S. Patent No. 5,469,736 U.S. Patent No. 6,084,826 U.S. Patent No. 6,501, No. 11
U.S. Pat. No. 4,525,644 U.S. Pat. No. 6,351,127 U.S. Pat. No. 6,690,170 U.S. Pat. No. 6,667,620
U.S. Pat. No. 6,380,744 U.S. Pat. 6,208,031 U.S. Patent No. 6,788,065
[0008]
It would be desirable to have an improved acoustic transducer with integrated electronics and
processing means without sacrificing performance and sensitivity.
[0009]
One aspect of the invention provides an acoustic transducer assembly for subsurface
applications.
The assembly includes a frame, an acoustic transducer element disposed on the frame, and an
electronics module disposed in the frame and coupled to the acoustic transducer element, the
electronics module processing signals associated with the transducer elements It is supposed to
be.
One aspect of the invention provides an acoustic transducer assembly for subsurface
applications. The assembly is coupled to a disk-shaped acoustic transducer element having a first
surface opposite the second surface, the second surface of the transducer element to process
signals associated with the acoustic transducer element An acoustic transducer element, an
electronics module, and an attenuation material, comprising: an electronics module coupled with
at least one signal lead; and an acoustic damping material disposed about the electronics module
and the acoustic transducer element. Is encapsulated in the sealing material leaving at least one
lead exposed.
[0010]
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One aspect of the present invention provides a method of assembling an acoustic transducer. The
method comprises the steps of disposing an acoustic transducer element on the frame means,
disposing an electronics module on the frame means, acoustically to the electronics module
adapted to digitize signals associated with the acoustic transducer elements. Connecting the
transducer elements and covering the acoustic transducer elements and the electronics module
with a sealing material to contain no liquid.
[0011]
The acoustic transducer of the present invention includes electronics technology packaged to be
suitable for exposure to harsh environments such as subsurface wells. The converter of the
present invention can be configured with a reduced number of elements and associated
electronics as compared to conventional designs. The circuit is minimized and the signal data is
preferably digitized near the converter. Transducers used as acoustic receiver arrays for
measuring sound waves in boreholes are compact and preferably propagate boreholes such as
monopolar, bipolar, quadrupole and higher order modes Should be individual in order to
measure the sound wave mode. Likewise, these acoustic transducers should operate in different
modes so as not to accept unwanted modes. For example, in measurements in bipolar or
quadrupolar mode, better quality measurements can be obtained by not accepting unipolar
modes. Embodiments of the invention include active sensors with integrated electronics that are
self-contained and suitable for exposure to subsurface conditions.
[0012]
FIG. 2 shows an embodiment of the converter 30 of the present invention. Transducer 30
includes a front end electronics module 32 with analog / digital circuitry 34 integrated with
acoustic transducer element 36 and disposed in frame 38. The coupling between electronics
module 32 and transducer element 36 is described below. Transducer element 36 may comprise
a piezoelectric element, a lead titanate (PT) element, a lead zirconate titanate (PZT) element, a 1-3
piezoelectric composite element, or any other material known in the art be able to. The
transducer element 36 of the present invention can be placed on the frame 38 with a
conventional transducer to add reliability and performance.
[0013]
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The frame 38 is shown as being two-dimensional or flat for clarity. In some embodiments, the
frame 38 can be formed as a strip, also referred to as a flex circuit (US Pat. Nos. 6,351,127,
6,690,170, 6,667,620, and No. 6,380,744). Embodiments of the flex circuit frame have a
polyimide film or polyester film having a thickness selected to allow bending or flexing (e.g., to
surround or fit into the void of the wedge). Or any suitable non-conductive material or dielectric
film substrate. Techniques for producing strips to form a flexible frame are described in US Pat.
No. 6,208,031. In addition to the flexible frame 38, other embodiments can be implemented
using a single phase or multilayer PCB frame. The conductors on the frame 38 can be formed of
a narrow strip of copper or other suitable material disposed on the frame, as known in the art.
Embodiments of the transducer of the present invention can be made waterproof by covering or
sealing the module and transducer assembly with a suitable resin or compound 40 (e.g., a rubber
layer), as shown in FIG. One or more leads connected to electronics module 32 remain exposed
for signal / power transfer.
[0014]
Embodiments of the present invention can also be implemented with multiple transducer
elements 36 disposed on a single frame 38. FIG. 4 shows an array of individual acoustic
transducer elements separated from one another (e.g., a few millimeters). The transducer array
can be implemented with "n" elements 36 mounted on the frame 38. When implemented as a
receiver, multi-element transducer 30 can be used to measure any borehole acoustic mode. The
transducer embodiment of multi-element 36 preferably comprises an electronic multiplexer
module 44 to smooth signal communication to or from transducer element 36. As mentioned
above, the conductors and circuit elements (e.g., item 46 of FIG. 3) form signal paths between the
components. Conductors and circuit elements are not shown in all the figures for the sake of
clarity. In these embodiments, the number of acoustic channels per transformer array can be
increased as they can be digitally multiplexed.
[0015]
Transducer 30 can also be provided with an acoustic damping material to reject unwanted
vibrations. FIG. 5 shows a side view of a transducer embodiment that includes a damping element
48 located on one side of the transducer element 36. FIG. Damping element 48 can be formed of
a heavy mass material (eg, tungsten) or any other suitable material as known in the art. When
operating the transducer element 36 as an acoustic source, the damping element 48 helps to
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reduce the vibration at the side B of the transducer element while improving the directionality of
the sound from the side A. Attenuation element 48 is shown in FIG. 5 on one side of transducer
element 36, but other embodiments may be differently (eg, completely surround transducer
element and clear side A). It can be implemented using a damping material arranged. The
acoustic transducer / attenuating element assembly can be placed in a void or cutout on the
surface of or within the frame 38 or can be completely contained in the rubber compound
forming the frame (item 40 of FIG. 3) reference).
[0016]
FIG. 6 shows another transducer assembly 30 of the present invention. A plurality of frames 38
are connected with the leads 42 to form a transducer assembly extension. Each frame 38 may be
implemented with a plurality of transducer elements 36 and electronics module 32 to generate
an acoustic array of "n" digital channels. The array may include one or more multiplexer modules
44 disposed on one or more frames 38 to efficiently channel transmit signals associated with the
transducer elements / electronics modules. it can. The embodiment shown in FIG. 6 includes a
connector 50 (also referred to as a "bulkhead") connected to the assembly to provide a single
signal / power connection. Conventional connectors 50 may also be used to practice the present
invention, as known in the art.
[0017]
Structural reinforcement of the transducer assembly of the present invention can be achieved by
strengthening the frame 38. FIG. 7 shows a side view of a transducer 30 embodiment with a
support 52 forming a rigid base of the transducer element / electronics module. The support 52
is formed of any suitable material, such as metal. The support 52 can be bonded to the flexible
frame 38 using an adhesive, fasteners, or any suitable means known in the art. The embodiment
shown in FIG. 7 is formed of an assembly of transducer element 36, electronics module 32, and
multiplexer module 44 overmolded with a rubber compound similar to the embodiment shown in
FIG. The support 52 is attached to the bottom side of the rectangular transducer assembly. The
support 52 can also be incorporated into the rubber compound as required. Some embodiments
include a plurality of supports 52 joined to other surfaces (eg, on the top and bottom) on the
transducer assembly, or divided supports 52 necessary for a particular example (see FIG. Not
shown). The heavy mass support 52 may also provide vibration damping and aid in acoustic
directivity similar to the embodiment described with respect to FIG.
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[0018]
FIG. 8 shows the general schematic layout of the electronics module 32 in the converter of the
present invention. Module 32 includes a preamplifier stage 100, a filter stage 102, an analog to
digital converter (ADC) stage 104, and a power amplifier stage 106. Module 32 is shown
connected to an n-to-1 multiplexer (MUX) unit 44 adapted to stream "n" signals to one channel
for output through lead 42. A switch 108 connected to the transducer element 36 switches
between position 1 and position 2. In position 1, converter element 36 is activated by power
amplifier stage 106, and the converter is implemented as a transmitter. With switch 108 in
position 2, preamplifier stage 100 receives the analog acoustic energy signal detected by element
36, which is processed through module 32 to implement the receiver. The small package and low
power electronics module 32 integrated with the converter element 36 minimizes power
consumption and improves noise reduction as the digital signal is cleaner compared to the
analog signal. Also, digitized signal data can be routed remotely for additional processing without
unwanted noise, if desired.
[0019]
The dual purpose transducer (i.e., source-sensor) of the present invention allows for pulse echo
measurements. As known in the art, measurements of the bi-directional travel time of the pulse
echo signal reflected from the borehole 12 wall can be used to determine the borehole geometry,
such as its radius. FIG. 9 shows an embodiment of the invention operating in pulse echo mode.
The downhole cage 13 comprises the transducer 30 of the present invention distributed at
several axial and azimuthal angles. Using the electronics module 32, the transducer element 36
can switch between modes to obtain pulse echo measurements in the borehole 12. The measured
acoustic signal data can be processed using conventional techniques known in the art.
[0020]
FIG. 10 shows an embodiment of another acoustic transducer 30 of the present invention.
Although a side view of the transducer 30 is shown, the assembly is "cup" shaped with a
contained disk transducer element 36 having a first surface A and a second surface B.
Transducer element 36 may be comprised of a piezoelectric element, lead titanate (PT), lead
zirconate titanate (PZT), a 1-3 piezoelectric composite synthetic material, or any other suitable
material known in the art can do. An electronics module 58 including a charge amplifier stage
abuts the transducer element surface B and converts the acoustic energy detected at the
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transducer surface A into a voltage signal proportional to the detected sound pressure.
[0021]
The signal / power is sent along one or more leads 60 coupled to the electronics module 58 to
operate the transducer in pulse echo mode or as a digital receiver. Attenuating material 62
surrounds the electronics module / converter assembly to form a cup, leaving the transducer
surface A clear. Any suitable damping material known in the art can be used. The entire cup
assembly is placed or sealed in a material 64 (eg, a rubber compound) suitable for waterproofing
the sensor to form a pack in which the leads 60 are exposed. This transducer embodiment is
much smaller in package compared to conventional cup transducers, and can be used in rods of
any size. For example, the cup transducer 30 of the present invention can be assembled with
dimensions in the range of 2.54 cm in diameter by 1.3 cm in height. Also, the electronics module
58 of the transducer 30 embodiment of FIG. 10 can be configured with switching means and
processing circuitry 59 as described in FIG. 8 to implement the source or sensor as desired.
[0022]
The small size, high sensitivity, directionality, and low power consumption provided by the
converter of the present invention make implementation in an infinite number of environments
and applications feasible. 11 (A) -11 (C) show three downhole wedges 13 similar to the wedges
of FIG. 1 equipped with an embodiment of the acoustic transducer 30 of the present invention.
The embodiment of FIG. 11 (A) shows an azimuthal angle converter array. The transducers 30 in
these configurations can use the flex circuit frame 38, individual PCB frames 38, or connection
frames 38 described herein. The embodiment of FIG. 11 (C) shows an array using the
embodiment of the cup transducer 30 shown in FIG. The small cup converter 30 configuration
represents a point source. Any of these arrays can be used for multipolar acoustic measurements.
Other embodiments may be implemented using any combination of the disclosed transducer
configurations. For example, the wedge could be equipped with the axial and cup type
transducers (not shown) shown in FIGS. 11 (B) and 11 (C). In addition to providing multiple
measurements, such an arrangement is also considered to provide backup acoustic sources and
sensors in case of failure.
[0023]
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FIG. 12 (A) shows the azimuthal converter bands from the embodiment shown in FIG. 11 (A). The
transducer 30 is disposed in the shallow depression 66 formed in FIG. 11 (A). FIG. 12B shows a
top view of the transducer 30 in the recess 66. FIG. The transducer 30 can be waterproof sealed
and exposed in the borehole so that it can be mounted on the cage (eg, with the rubber
compound) using any suitable means known in the art ). Also, a shield assembly 68 may be
placed on the barb 13 to cover and protect the transducer 30 against wear. The shield 68 can be
formed of metal, a plastic compound (eg, “PEEK®”), or any suitable material known in the art.
U.S. Patent No. 6,788,065 describes various rods configured in a recess and shield configuration
that can be used to practice embodiments of the present invention. The shield 68 is preferably
configured with an air gap or opening (e.g., a hole or slot) to allow passage of borehole fluid in
the spacing between the shield and the face of the transducer 30. The shield 68 can be mounted
on the cage 13 using fasteners or any suitable means known in the art.
[0024]
The array of azimuthal angle converters 30 shown in FIGS. 11 (A) and 12 (A) encircles the entire
circumference of the cage 13 or a specific sector as shown in FIG. 12 (B), Alternatively, they can
be arranged in a staggered azimuthal sector (not shown) along the longitudinal axis of the cage.
FIG. 12C shows a top view of the array of transducers 30 arranged around the circumference of
the cage 13. The miniaturization of the transducer embodiment of the present invention allows
for placement within a smaller air gap within the cage 13 as compared to conventional
transducer designs. This provides a downhole tool with improved mechanical strength and
improved acoustic response. The miniaturization of the transducers 30 makes it possible to place
them on the cage with minimal spacing between the transducer elements 36. For example, using
a downhole tool equipped with an axial array of transducers 30 spaced by only a few centimeters
(e.g., 5-16 centimeters) as shown in FIG. 13, the desired length along the borehole Can transmit
and receive a narrower envelope of sound waves along the. Such measurements will provide
improved imaging and formation analysis functions.
[0025]
FIG. 13 shows an axial transducer array similar to the embodiment shown in FIG. 11 (B). One
transducer 30 or series of transducers 30 (see FIG. 6) can be arranged in a shallow channel or
recess 70 formed in a cage. As mentioned above, a shield 72 can be placed over the transducer
30 to protect against wear. The shield 72 can be formed of any suitable material, and preferably
consists of one or more openings. As shown in FIG. 13, the openings 74 can be formed at
different locations of the shield 72. From left to right in FIG. 13, the first shield 72 is comprised
04-05-2019
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of two half-moon shaped openings 74 formed in the edge of the shield. The middle shield 72 is
composed of an opening 74 formed at the center of the shield. The rightmost shield 72 is
configured with an opening 74 formed at the opposite end of the shield. Although not shown in
all the figures for clarity, as is known in the art, the transmission of signals / power to or from
the converter of the present invention may be provided using any suitable means.
[0026]
FIG. 14 shows a side view of an embodiment similar to that shown in FIG. In this embodiment,
the recess 70 is formed with a ramp at one end, and a series of coupling transducers 30 are
arranged in the recess. Transducer 30 can be covered using a one-piece shield 72 or several
individual shields (see FIG. 13). Transducers 30 are coupled together as described above, and
signal / power is routed through connector 50 as described in FIG. The connector 50 allows
signal / power transfer between the transducer 30 and other components (e.g., electronics,
telemetry, memory storage, etc.) as known in the art. One or more leads 82 connect to a passage
80, also referred to as a feedthrough.
[0027]
FIG. 15 shows a cross-sectional view of an embodiment of the transducer of the present
invention disposed in a cage 13. In this embodiment, the acoustic transducer elements 36 are
embedded or overmolded in a rectangular shaped rubber composite 40 (see FIG. 3). Composite
40 is formed with a central portion that is stepped or raised such that shoulder 84 is formed. A
rectangular shield 72 covers the transducer. The shield 72 conforms to the transducer composite
40 by means of the projections 85 fitted on the shoulders 84 and forms the same surface with
the exterior of the scissor 13. The recess 70 in the wedge 13 is formed with an extension or lip
that receives the transducer / shield structure and holds the shield 72. Optionally, a support 52
can be added to the composite 40 (see FIG. 7). Although one transducer element 36 is shown in
FIG. 15, the transducer can be implemented using a multi-element or segmented transducer (see
FIG. 6) array. Returning to FIG. 14, the transducer composite 40 structure of FIG. 15 and the
manner in which the shield 72 slides down the ramp 76 and into the recess 70 under the lip 86
is depicted. Once in the recess 70, the shield 72 can be fastened to the scissor 13 using fasteners
(eg, screws) or any suitable means known in the art.
[0028]
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FIG. 16 illustrates another transducer 30 embodiment of the present invention. The frame 38,
equipped with one or more transducer elements 36, electronics module 32, and an optional
multiplexer 44 as described herein, is an elongated, substantially rectangular transducer
assembly (FIG. 3 and FIG. The rubber composite 40 is sealed to form a similar. The overmolded
composite 40 is constructed using a plurality of extension tabs at opposing edges of the
rectangular assembly. Transducer 30 may be implemented using a support (see item 52 in FIG.
7) on any surface (not shown), as desired. Signal / power leads are not shown for clarity.
[0029]
FIG. 17 shows the downhole wedge 13 configured with a recess 70 to receive the transducer 30
shown in FIG. The recess 70 is stepped with the lower groove 75 for receiving the transducer 30
assembly. A series of recesses 77 are formed in the side of the lower groove 75 to match the tabs
41 extending from the side of the transducer 30. The tab 41 holds the transducer assembly when
placed in the lower groove 75 and prevents radial and axial movement. The recess 70 is also
configured with an extension or lip 86 that extends along the sides of the channel. FIG. 18 shows
a cross section of the wedge shown in FIG. 17 with the transducer embodiment shown in FIG.
[0030]
As shown in FIG. 18, the shield 72 is disposed above the transducer 30 in the recess 70. The
shield 72 is configured using the projecting portion 85, and forms the same surface with the
outside of the cage 13 as described above. The protrusions 85 on the shield 72 compress the
rubber tab 41 on the transducer 30 and secure the transducer in the recess 70. Also, the
compression on the tab 41 provides a reaction force that presses the shield 72 against the lip 86
to prevent backlash. FIG. 19A shows an embodiment of the shield 72 of the present invention.
FIG. 19 (B) shows another shield 72 embodiment of the present invention with smaller
projections 85. These shields can be configured with one or more openings 74, as described
above.
[0031]
Returning to FIG. 17, one segment of the recess 70 is shown as formed with a narrow channel C,
as compared to another segment having a channel width D. The segments of wide depressions 70
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are configured with enlarged depressions 78 formed on either side of the channel. With this
embodiment, the assembly of transducer 30 of FIG. 16 is simply dropped into recess 70 to
facilitate repair and replacement. With the transducer 30 placed in the recess 70 and the
appropriate signal / power connections made as known in the art, the shield 72 is simply
dropped into the wide recess 70 and the lip 86 Sliding down and into position just above the
transducer 30. Based on the length of the transducer 30, one or more shields 72 can be used to
cover the entire length of the transducer.
[0032]
FIG. 20 shows another shield 79 embodiment of the present invention. This shield 79 is shown in
FIG. 19A and FIG. 19A except that it includes a receptacle 81 formed without a flanged
projection (item 85 in FIGS. 19A and 19B) and extending from the side thereof. It is similar to the
shield shown in FIG. The shield 79 is configured with an appropriate width to fit snugly in the
wide channel portion D, and is configured using one or more openings 74 as described herein. It
can also be done. The shield 79 can be formed of any suitable material. The shields 72 and 79 of
the present invention can be constructed with smooth (i.e. flat) or rounded surfaces as required
and are suitable materials known in the art (e.g. metal, plastic, synthetic) Compounds,
composites).
[0033]
FIG. 21 shows a cage 13 equipped with an embodiment (see FIG. 11B) of a pair of axial direction
transducers 30 according to the invention. This embodiment is implemented using transducer
30, recess 70, and shields 72 and 79 as described in FIGS. 16-20. A plurality of individual shields
72 have been slid into recess 70 to cover transducer 30, as described above. Each set of shields
72 is held by shields 79 as shown in FIG. 20 so as not to slide out of the recess 70. The shield 79
is fixed on the collar 13 by means of fasteners (eg screws, rivets) inserted into the appropriate
orifices (see item 87 in FIG. 17) formed in the collar through the receptacle 81. Be done.
[0034]
Unlike conventional acoustic transducers (e.g., oil-corrected transducers), the disclosed
transducer 30 is mounted within the rod using various means known in the art due to its small
size and integrated construction Can be held. For example, when implemented in a wireline
04-05-2019
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instrument or other application where wear is not a determining factor, the transducer 30 can be
placed with the appropriate compound in the air gap of the instrument (not shown). The method
of assembling the embodiment of the acoustic transducer of the present invention involves
placing the acoustic transducer element on the frame means as described herein. Next, an
electronics module adapted to digitize the signals associated with the transducer elements is
placed on the frame means and connected with the acoustic transducer elements. The transducer
element and electronics module are then covered with a sealing material to provide a liquid free
assembly.
[0035]
FIG. 22 shows another embodiment of the present invention. This embodiment includes a cup
transducer 30 shown in FIG. Transducer 30 is attached to a downhole tool 90 disposed in
borehole 12 which passes through the Earth's formation. Transducer 30 is positioned such that
transducer element 36 is exposed in the borehole. Tool 90 also includes a multi-axis
electromagnetic antenna 91 for subsurface measurements and electronics 92 and 93 with
appropriate circuitry. The tool 90 is shown supported in the borehole 30 by a logging cable 59 in
the case of a wireline system and by a drilling string 95 in the case of a drilling system. For
wireline applications, the tool 90 is raised and lowered within the borehole 30 by a winch 97
controlled by the surface equipment 98. The logging cable or drill string 95 includes conductors
99 that connect the downhole electronics 92 and 93 to the surface equipment 98 for signal and
control communication. Alternatively, these signals may be processed or recorded in tool 90 and
the processed data may be communicated to surface equipment 98 as known in the art. The
transducer of the present invention can be attached to conventional downhole tools using a
variety of known techniques. The electrical leads from the converter of the present invention can
be routed as desired since the electronics module / multiplexer can extend the long cable. The
disclosed transducer embodiments can be implemented in measurement and communication
devices known in the art using conventional electronics, connecting components (eg, optical
fibers), and connectors. Those skilled in the art will appreciate that the present invention is
applicable to and practiced in any field where acoustic transducers are used, and the present
invention is not limited to subsurface applications. It is also recognized that the disclosed
converter is not limited to the operation of any particular frequency or frequency range.
[0036]
FIG. 1 is a schematic view of a conventional downhole sonic tool. FIG. 1 is a schematic view of a
converter according to the invention. FIG. 1 is a perspective view of a sealing transducer
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according to the invention. FIG. 1 is a schematic view of a multi-element converter according to
the invention. FIG. 1 is a side view of an attenuation converter according to the invention. Fig. 2
shows a split transducer array according to the invention. Fig. 2 is a side view of a reinforcement
transducer according to the invention. FIG. 5 is a schematic view of a converter electronics
module and a multiplexer module according to the invention. FIG. 1 shows a downhole cage
equipped with an acoustic transducer according to the invention. Fig. 1 is a schematic view of a
"cup" type transducer according to the invention. FIG. 1 is a schematic view of a downhole cage
incorporating an azimuthal configuration transducer according to the present invention. FIG. 5 is
a schematic view of a downhole cage incorporating an axial alignment transducer according to
the present invention. FIG. 1 is a schematic view of a downhole cage incorporating a cup-shaped
transducer according to the invention. FIG. 1 is a schematic view of an azimuthal configuration
converter according to the invention. FIG. 12B is a top view of the azimuthal transducer of FIG.
12A. FIG. 5 is a top view of the transducer of the present invention azimuthally disposed about
the circumference of the cage. FIG. 5 is a schematic view of an axial transducer arranged in a
bowl according to the invention. FIG. 5 is a side view of a coupling transducer arranged in a bowl
according to the invention. FIG. 5 is a cross-sectional view of a transducer arranged in a bowl
according to the invention. FIG. 1 is a perspective view of an encapsulation transducer according
to the invention. FIG. 17 is a perspective view of a cage configured to receive the transducer of
FIG. 16; FIG. 18 is a cross-sectional view of the transducer of FIG. 16 disposed in the trough of
FIG. 17; FIG. 1 is a perspective view of a transducer shield according to the present invention.
FIG. 7 is a perspective view of another transducer shield according to the present invention. FIG.
7 is a perspective view of another transducer shield according to the present invention. FIG. 5 is
a perspective view of a bowl and a shield and a transducer according to the invention; FIG. 1 is a
schematic view of a downhole tool incorporating an embodiment of a transducer according to the
present invention.
Explanation of sign
[0037]
12 borehole 30 cup type converter 90 downhole tool 91 multi-axis electromagnetic antenna 92,
93 electronic equipment 97 winch 98 ground equipment
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