CA2035606A1 - Borehole acoustic logging system having synchronization of acoustic transducer rotation and output - Google Patents
Borehole acoustic logging system having synchronization of acoustic transducer rotation and outputInfo
- Publication number
- CA2035606A1 CA2035606A1 CA002035606A CA2035606A CA2035606A1 CA 2035606 A1 CA2035606 A1 CA 2035606A1 CA 002035606 A CA002035606 A CA 002035606A CA 2035606 A CA2035606 A CA 2035606A CA 2035606 A1 CA2035606 A1 CA 2035606A1
- Authority
- CA
- Canada
- Prior art keywords
- transducer
- signal
- electrical signal
- rate
- hertz
- 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.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/40—Seismology; Seismic or acoustic prospecting or detecting specially adapted for well-logging
- G01V1/44—Seismology; Seismic or acoustic prospecting or detecting specially adapted for well-logging using generators and receivers in the same well
- G01V1/46—Data acquisition
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S367/00—Communications, electrical: acoustic wave systems and devices
- Y10S367/911—Particular well-logging apparatus
Abstract
ABSTRACT
An elongated borehole logging tool employs an acoustic energy transducer for directing acoustic energy pulses toward a bolehole wall at a repetition rate synchronised with rotational speed of the tool within the borehole.
An elongated borehole logging tool employs an acoustic energy transducer for directing acoustic energy pulses toward a bolehole wall at a repetition rate synchronised with rotational speed of the tool within the borehole.
Description
~ ~ 3 ;~
SXSrEM E~ A~C ID~G OP ~OE ~ra~
This invention relates to a system for acoustic logging of subsurface formations, and mGre part:icularly relate~ to a systRm for controlling an acoustic trar~ducer to direct pulses ~f acoustic energy toward a borehole wall at a repetition rate synchronised with ~he rotational speed of the transducer within the ~orehole.
In US-A-3,369,626; US-A-3,718,204; and US-A-3,728,672, ~here æ e disclosed methads of and apFaratus for scannir~ the walls of a borehole with accustic energy. In these patents a borehole televiewer lo~ging tool employs a trarEmitter and a receiver of acoustic en~rgy which are rotated within the bor~ehole. The transmitter is cyclically energized to pr~vide a ~e~m o~ acoustic energy pulses for scanning the walls of the borehole. Reflected acoustic pulses are received ky ~he receiver transmitted acoustic pulses and are converted to reflection signals for recondiog on an electron keam display device. A sweep signal is generated ~ach time the accustic energy beam is rokated through a 3~0 scanning pattern. Such sweep~;signal is applied to the harizontal deflection plates of , -the display device to sw~ep an elec*ron beam horizontally across he face of ~he display device~ The reflection signals are applied to the Z-;axis of the display deYioe to in~ensity modulate th2 electron keam as the beam is swept across the face of the display d v~ce to provid~ a picture which is a functi~n of the :.
tLme or dlst~nce from the transmitter and recs.iver to the wall oP
the bor~hole and o~ the density of the korehole wall.
~ In bGth 1he above-d~scribed pa~ents the ccmb.~nation of tr~n=lucer rota~ n along with vertical movffment of the borehole telev~eKer logg~ tool along the length of the borehole r~sults in a continuous spiral of the borehole wall being scann~d.
~ : .
: .
SXSrEM E~ A~C ID~G OP ~OE ~ra~
This invention relates to a system for acoustic logging of subsurface formations, and mGre part:icularly relate~ to a systRm for controlling an acoustic trar~ducer to direct pulses ~f acoustic energy toward a borehole wall at a repetition rate synchronised with ~he rotational speed of the transducer within the ~orehole.
In US-A-3,369,626; US-A-3,718,204; and US-A-3,728,672, ~here æ e disclosed methads of and apFaratus for scannir~ the walls of a borehole with accustic energy. In these patents a borehole televiewer lo~ging tool employs a trarEmitter and a receiver of acoustic en~rgy which are rotated within the bor~ehole. The transmitter is cyclically energized to pr~vide a ~e~m o~ acoustic energy pulses for scanning the walls of the borehole. Reflected acoustic pulses are received ky ~he receiver transmitted acoustic pulses and are converted to reflection signals for recondiog on an electron keam display device. A sweep signal is generated ~ach time the accustic energy beam is rokated through a 3~0 scanning pattern. Such sweep~;signal is applied to the harizontal deflection plates of , -the display device to sw~ep an elec*ron beam horizontally across he face of ~he display device~ The reflection signals are applied to the Z-;axis of the display deYioe to in~ensity modulate th2 electron keam as the beam is swept across the face of the display d v~ce to provid~ a picture which is a functi~n of the :.
tLme or dlst~nce from the transmitter and recs.iver to the wall oP
the bor~hole and o~ the density of the korehole wall.
~ In bGth 1he above-d~scribed pa~ents the ccmb.~nation of tr~n=lucer rota~ n along with vertical movffment of the borehole telev~eKer logg~ tool along the length of the borehole r~sults in a continuous spiral of the borehole wall being scann~d.
~ : .
: .
- 2 - 2~3~06 The resultLng display is a pic*ure of the density of the material for ~ the walls of the borehole at dif~er~nt depth points.
Ih~s scan mng of the borehole wall pe~mits the determination o~
the actual ccnfiguration o~ the borehole. In addition, it permits the determination of anomalies which may e~ist at different depkhs in the borehole. For example, these an Q lies ~ay be a fault or a fracture in the formations traversed ~y the borehole.
According to ~he present invention there is provided a system for the acoustic lo~gLng of iNbsurface formations surro ~ a borehole, ccmprising:
a) a ~r ~ cer for directing pulses of acoustic energy toward the wall of said borehole and for receiving direct reflections of said acoustic energy from said borehole wall;
b) n~ans for rokatin~ ~aid transducer about a rotational axis parallel to the axis of ~he barehole;
c) a ~heel rotated Ln synchronism with said transducer and having a plurality of teeth ~qually spaoed about its perip~ery;
d) a sensor spaoed Ln juxtapcsi~ion with said wheel for d~kecting ~he rate o~ mavement of said teeth past said sensor and ~or producing an electrical signal havin3 a plurality o~ pulses wit~ a repetition rate representative of the rate of mcvement of said tee~h Fast said sensor; and e) means responsive to said electrical signal for controlling said transducer to direct said F~S~s o~ acoustic energy~toward saicl borehole ~all at a repetition rate synchrom s~d with the rotational æpeed of said tran~duoer;
Pre~erably .said oontrol me3ns converts ~aid electrical signal to a tx~ r excitation signal hav ~ a p~l æ ~a~e synchroris~ i to the repeti~ion rate o~ the pulses comprising said electrical signal.
~ 3 203~fiO~
Desirably said oontrol means a~mprises:
(a) an oscill~tor for generat~ng said transducer excitation signal having a pulse rate that is a multiple N of the repetition rate of the pulses of said electrical signal, (b) me~ns fo~ dividing said transducer excitation signal by N; and .
(c) a detector ~or ccmp~r~ng the phase of said transducer excitation si~nal as di~ided by N with the phase ot`
said electrical signal to pxovide a phase error signal to said oscillator for synchronising said excitation 5ignal to said !". ' electrical 5ignal 50 that the rate at which said transducer directs p~lses of acoustic energy toward said borehole wall is synchronised with ~he rate of rctati~n of said transducer.
Preferably th~ means ~or rota~ing said transducer c~mprises a mokor ha~ing a plurali~y of ~paed variations during eac~ revolution.
In one embodi~ent the oQntrol mans comprises: :
(a3 an oscillator for produc mg a t~alsducer excitation si~nal having a E~se rat2 that is a mNl~iple N oR the pulse rate of said electrical si~nal; ~ : .
(b) a divide-by-N:coun~er that divides the pul æ r~te of :~
id trsnrducer e~ci~ation signal by said multiple N; and (c) a phase detector for OomparLng said electrical si~nal with ~ e ~ of sai~ ~ounter to provide a phase error signal for con~rolIing said oscillator so that the pulse r~e of said tre~ ducrr ex~i~ation si~nal is phase locked to the ~ul6e rate of said eleckrical signal whereby the rate a~ whi~h said txan~ducer dires~ acoustia ~nergy pulses tcward the borehole wall Ln synchron~ with the speed variakisns o~ said motor dh~ing each revolution ~ that said a ~ ic ~n~y pulses are directed from said ~ransduc~er ~t equall~ qpaced a~imuthal positions aboNt ~ e r~ta~ional aX~fi 0~ said ~ cer-:
~3~
In another O ~:
(a) the means for rokatLng the transducer ccmprises a motor for ro~ating the tLansduoer at a ;ra~e of R re~olutions per second with a plurality o~ aooeleration and deceleration cycles per revolution;
~ b) the wheel has T ~e~th ~ lly spaced about its ou~r periphery and is rotated in synchronism with said motor;
(c) the electrical signal p~oduced by tha sensor is a Rx~ hertz electrical signal repreæntative of the rate of movement o~ said teeth past said sensor ~ach second;
and said ~ further oomprises:
(d) a voltage contr~ll0d ~scillator ~r pr~ucing a P
hert2 trans~ucer excitation signal;
(e) a ocunter that divides said ~ransducer aYcitation signal by N to provide a P/N hertz ocun~er signal; an~
~ f) a phase de~ecto~ ~or comparing the phase o~ said RxT
hert3 electrical signal wi~h ~e ~hase o~ said P/N hertz si~nal to~provide a Fhase exror si~nal to con~rol the Yolta~e of said voltage contrDlled oscilla~r to cause said P hertz trar~ducer excitation signal to be phase locked tD :said ~xT hertz elec*rical slgnal;~so that ~aid trancducer excit~tion si~nal causes said tranc~Lcer~to dir0~t P/R acoustic energy Fulses toward the bcrehDl- wall at equall~ ~paos~ azimuthal ~ itions about said rotatlonal~axis for eadh rev~luti~n of said ~xansducer.
In ~his e~bcdi=:nt it is preferr0d th~t~
: a) R:r~pre#eY~:~ 6 rev~lutions per seoond, b) T represents 64 teeth, c) Rxr ~repre~ nts a 384 hertz electrical ~ignal, d3 P represents a 1536 hert2 transducer exci~a~ion : e1: N rep~esents a division o~ said txansducer e~citation si~nal by~4, : .
: ~: . , : -.
- 5 ~ O S
f3 PjN represents a 384 hertz cGunter signal, and g) P/R represents 256 accustic energy pulses per revolution of said transdu~er.
Reference is now made to ~he accompanyLng drawings Ln ~ich.
FIG. 1 illus*rates a bar.ehole logging tool with which the present invention may be uti.lized;
FIGSo 2~ 3 and 5 are electrical circuit di~gr~ms of the circuitry employed in the present invention for synchronising the generation of accu~tic energy pulses by the transmitting trans~ucer illustrated in FIG. 1 with the rotational speed o~ the trans~ucer as driven by the mo~or illustrated in FIG. 1; and FIG. 4 illustratRs a t~c-dlmensional light intensity ~ ion representing the display of acaustic reflection ~ignals recorde~ with ~he borehole 1 ~ tool o~ FIG. 1.
: Fo~ the purpose of illustratLng the type of borehole ~colstic logging system with ~ the apparabus o~ the present Lnvention nay be employ~d, a general de~cription~of the loggLng shc~n Ln FIG. 1 will be ~irst pYesen*ed, follownng which details of the apFsratus of:the present mvention will be described~
Referring now ~o FIGu 1, a bGrehole t~leviewer logging tool 11 is lcwered into bc~ehole 10 by means of a loggLng cable 12. IogqdnJ~tool 11 comprisss a transducer ~ss~m~ly 13 which acts as hoth a trans~Lttcr 14 an~ reoeiver 15 of acoustic energy.
m e beam of high ~requency accu~tic energy is xotated withLn ~he borehole to circNl æ ly scan the walls of the borehole. Such rotation is effected ~y ~ of n~or 16. While it is understood:that trenr~luc3r assembly 13 co~prises a æpara~e transmitt~r 14 and a reoei~ee lS, a sm gle trans~ucer acting bo~h as tlars~itter an~ receiver may ke utilized~ The transduce~
as~e~bly 13 is r ~ about the borehole axls by means o~ mokor :
, ::: :
:
, ; ; ,, , . ; , . . . . . .
:, :: . , .:, . . . . . . ..
.. : : .. . . .. ..
20~6~
16. m e frequency of the accus~ic en~ transmitted by way of beam path 21 toward the wall 22 of bor~lole 10 is determined by the pulser 17.
Logging tool 11 also incl~des a ~agnetometer 24, mounted for rotation wi~h the logging tool ll, which produces an output pulæ each time magnetic North is detected d~ring rotation. Such magnetometer output pulse is applied uphole to sawtooth sweep genexator 25 which pxovides a horizontal sweep signal to the horizontal deflection plates of an electron beam display device 26 for horizontally driving an electron beam across the face of display device 26.
Each horizontal sweep of the electron keam across the display device 26 is displaoed vertically ~rom the start of the sweep to ~he end of the s~eep in proportion to the v~rtical movement of the logging tool 11 within the borehole 10. Such displacement is proNided by means o~ a po~entiometer 27 which is coupled:by Plectm me~hanical li~kage 28 ~ a sheave 29 over which Ing cable:12 p~ssee. Vertical adnanoement of logging cable 12 alon~ the korehole a~ls ro~ates ~heave 29, such: rotation causing:eleotrcmech3ndcal linkage 28 to vary the location of the wi]~er arm on potenticmeter 27, thereby applyin3 ~o the vertical deflection pla~es of display device 25 a voltage which i~ :
;:prrpartio~al to the depth of the logging tool withun the borehole~ ~he resulting picture displayed on display device 26 is a series of side~by-side, substantially hor.iæ~ntal beams, the start of each beam traoe located at the vertical position on the : :
ace of the display ~evice where ~he preceding beam trao~
te~m~lted.
Reflected acoustic eneryy Eulses 23 æ e receiv~d by the ~ecelver 15 o~ tr~ns~uGer assembly 13, and signals representative ",:. :
of such reflections are appli~d to ~he Z~axis o~ display device 26 by ~ay of a si~nal amplifier 40 and detector 41, lccated : :
. , ,, , .. ,~. .. : :,,, : ": , . . ... . . . . . .
~0~6a~
F-5646-L ~.
downhole, and a pulse amplifier 34, g~te 35, and ~ r 36 located on the surface of the earth. Such input to the Z-input terminal of displa~ devîce 26 serv~s to int~sity m~dulate the electron beam in accordanoe wi~h the amplitudes of the refle~ion signals.
Ord ~ logging cabl~s are not suitable for transmission of high frequency signals, such as 2 mgahertæ, to the surface;
therefore, after bei~g amplified by signal amplifier 40, the refl~ction signals are applied to detector 41 which generates a lower ~r.equency ~ignal in ~he form o~ the envelope of the reflection signals. Such lower frequency signals, prefsrably in the range of 20-5n kilohertz, can be transmitted to the surface over ordlnary logging cable without a~preciable signal loss. The ou~put oP detestor 41 is a~plied to the input of pulse amplifier 34 by mRans of condu~tor 19.
Pulser 17 also prcvides an autput to a sync multivihrator 37, dslay monostable ~ lti ~ tor 38, a~d gating multivibrator;~.
39. The output o~ gating m~ltivi~rator 3g is an indication ~f the tIme period bebwaen transmltted acoustic energy pulses and : :
during which reflected acoustic energy pulses are expected ~ be receiv~d at receiver 15, such cutput being applied to gate 35 to allow reflecting signals to pass from pulse amplifier 34 through ~ate 35 and enhancer 36 to the m~dulating ~ t o~ display device 2~. :
~ hen pulser 17 generates an e~ci~atian pulse, a portion of this p~ cross-~eeds into re~eiv~r 15. A:Lso, ~hen a sync pulse is generatecl by pulsex 17 and sent uE*Iole via conductor 18, a portion of the ~æ crossf~ls ~to receiver c~nductor 19. rrO
E~ev~t ff~ese cro~;s-fe~d si~nals ~r~m intensity r~llat.~ng t~le :el~n bez~n o~ clis3play device 26, gate 35 is open only du~ing ~t portion of ~ime dur:in~ which reflected pulæs are expec~ed to be ~ frc:qn tha wall~; o~ t:he bQ~ole. Eac~ time a ~;ync . .
&
pulse is received by sync multivibr~dtor 37, it triggers into its unstable state for an output for a period of time almDst as long as the time period between transmitted acoustic pulses. At the same time that the output of sync multivi ~ator 37 goes positive, the delay moncstable multivibrator 38 is triggered into its uns~able stage for a period of tLme endin~ just prior to the anticipated arrival time of a reflected pulse at reoeiver 15. As :
the trailing edge of the outpu~ of delay multivi~rator 38 goes ~egative, the ga~ing monostable multivibrator 39 i5 triggered into its unstable state to generate a pcsitivergoing cutput, which triggers gating mwltiv;hrator 39 to provide a signal to gate 35 to allow passage therethrough of only those signals represen~ative of reflec~ed pulses. Therefore, only ~he envelopes of the reflection signals pa~s through gate 35 to enhancer 36.
HavLng now described a b~rehole televiewer logging system with which the present invention may be prackised, reference is made to FIGS. ~-5 along wi~h th~ following detailed description of the apparatus of the present invention for use in ~ controllin~ an aocustic tran~duoer to direct pulses of acoustic : ~ boward a ~or~hole ~all at a repetition rate synchronized with ffhe rotational s~peed o~ the transducer within ~he borehole.
Ref ~ firstly to FIG. 2, there is shown in block diagram form the ac~ustic tr ~ uoer synchronisation featuxe of the pres2nt inventi~n for use with the borehole televiewer loyging system of FIG. 1.
: A wheel 42 is rokated in synchronisation with the motor 16 ~ the transduce~ 13. m~ outer periphery of wheel 42 cantains i a~plur~lity of ex~lly spaoed ~ee~h. In juxtaposition with wheel :42 is a sensar 44 which detecks the mechanical rokation ~ wheel 42 by sens~ng the movement o~ ~eeth 43. Sensor 44 pre*erably ;:;
cc~prises an elex~ic coil wrapped around a magnatic core. AS
:.
, ~ , ' , '. !. ~ , . i. '. ' . .:
~5f~0~
each tooth passes ~he sensor 44, ~n electrical pulse is pro~lced ky sensor 44 and 6haped by pulse shaper 45. The rate at which such pulses are producsd is dependent ~pon motor speed ~uring each revolution which varies due to a number of acceleration ~nd decelera~ion cycles oorresponl~g to the number o~ poles present within the motor (i.e., a bwo pole moto:r having two acceleration and deceleration cycles p~r revolution). m ese pulses are utiliz~d by synchronisation unit 46 to control puls~er 17 so that the transducer 13 produces the same number of acoustic energy pulses ea~h revolution of motor 16 and ~he pul æ s are directed towand ~he borehole wall at equally spaced az.umuthal positions akout the rotational axis of the txansduc~r 13 regardless of motor speed ch3nges during each revolution.
~ eferring now to FIG. 3, ~here is shown in detail the ccmponents of the synchr~nisation unit 46 of F~G~ 2. Pulses from pulsQ shapar 45 are c3upled to the 1 input of phase lock locp 50 ha~ing a pbase detector 51, a low pass .filter 52 and a voltage :~
con~rolled oscilla~or (VCO) 53. In a pre~erred operation of the borehole loggin~ syst~m the mot~r 16 rota~es the transduc~r 13 at 6 revolutions per second and ~he wh0~1 42 empl~ys 64 teeth.
Iherefore, the sensor 44 and pulæ shaper 45 provide a 384 hert2 electrical signal to the 1 inpu~ of phase detector 51. The oscillator ~3 is vo~tage controlled to produced a 1536 hertz transducer excitation signal to ~he pulser 17. ~.his 1536 hertz transduoer e~citation signal is also coupled to a di~ide-~y-N
mter 54 which divides the 1536 hertz signal by 4 to provide a 384 hert2 signal to the 2 input oE phase detector 51a Phase differe~es between the paLr o~ 384 hRrtz signals input to phase detector 5~ æ e caused by motar speed variations that vary the phase of the 384 hertz electrical siynal fram sensor 44 and puls~
~haper 45. Dekector 51 provides a phase e~ror signal ~ ~e ~ tive of such Fhk~se dif~erences which passe~ thro~h low :
,~
~ o ~ Q ~
F-5646~L
pass filter 52 to control the vol~age applied to the oscillator 53. This voltage control causes oscillator 53 to vary its sutput to reduce the phase diffexence to zero so as to maintain phase lock within the lcop. m is output is also appli~d as the excitation signal to pulser 17 to cause pulser 17 to ~xcite trar~sducer 13 for the production of acoustic energy pulses.
Since this transducer excitation signal is derived from wheel 42 rotating with mo~or 1~ a~d transducer 13 by way of a phase lock loop, it is in synKhronism with transducer 13 rota~ion and causes transducer 13 to produce acoustic energy pulses at a repetition rate synchronised with mokor speed variations each revolution.
As~ordingly, an equal nu~ber o~ acoustic energy pulses are produced each rev~lution and they are azîmuthly egually spaced about the axls of ~Qr rotation despite the fact that the motor accelerates and decelerates a~ least twice ~i.e. for a dipole m~tor) durLng each revolution.
The importance of providing an exact number of acGustic ~ pulses for each trans~uGer rev~lution at equally spacad azimlthal positions can best be seen by re~erence to FIG. 4 which illustrates an aooustic aner~y re~lection signal being presented on display device 26 as a two dimensional light intensity function f(k, l~ where 1 is a row (line) number on the display k is a point (pixel) n~mber on a line. The total numb~r of lines in the im~ge is L and ~he tokal number of pixels p2r l.Lne ( ~ 1 t~ the tL~al number of c~lumns~ is K. The value of ~ ~t spa~ial coordinates (k, l) of FIG. 4 is e~ual to ~he ~mplitude (or time of arri~l~ of the re~ection si~nal received by the logging tcols rec~ er a~ azimuth k ~nd d~pkh l. This value f(k, 1) will determine ~he intensity o~ ~he pi~el (k~ l) on the display. The ima~e on ~he display consists of, for example, 256 horizontal lines }~ 256 pixels per line. '~his represents 256 scan line~ and 256 ev~nts per rev~lution of the transduoer. TbD
- :Ll 2Q3~0fi much or too little recorded reflection information during a given revolution will distort the 256 pixel image. Thus, it can be seen that synchronising the excitation, or pulsing, of the transducer to its rotation ~o that no mare or no less than the full display of 256 pixels is produced~sach revolution.
While a particular embcdim/nt of the present invention has been describ0d an~ shown in FIG. 3, it will be understood that the circ~ut components are merely repr~sent~tive of such particular embod~ment and various other types and values of circuit components may be utilized without departing fr~m the spirit and soope of the invention as se~ forth in the appended claims. In ac~7rbarce with such p~rticular embodiimnt, the phase detector 51, low pass ~i~ter 52 and VC0 53 may preferably be packaged in a single CD 4046 chip supplied ky ~ Q as shown in FIG. 5 with the circled numbers representing pin numkers. The following Table sets forth speci~.ic types ~nd values o~ circui*
elements for the enbodL~mnts o~ FIGS. 3 and ~.
Referense Desiqnation Description ~-~ Detec$or 51 CD 4046 ~RCA) Low Pass Filter 52 CD 4046 (RCA) VOO 53 CD 4046 (RCA) Divide-~y-Counter 54 CD 4520 (~CA) R~sisto~ 48 and 59 lOK
ResistQr 55 lOOK
Capacitor 49 0.047 uf Capacitor 57 0.1 uf , .
Capacit~r 58 820 pf ~V 5 vrc .
; , ;, , ~ , ", .
Ih~s scan mng of the borehole wall pe~mits the determination o~
the actual ccnfiguration o~ the borehole. In addition, it permits the determination of anomalies which may e~ist at different depkhs in the borehole. For example, these an Q lies ~ay be a fault or a fracture in the formations traversed ~y the borehole.
According to ~he present invention there is provided a system for the acoustic lo~gLng of iNbsurface formations surro ~ a borehole, ccmprising:
a) a ~r ~ cer for directing pulses of acoustic energy toward the wall of said borehole and for receiving direct reflections of said acoustic energy from said borehole wall;
b) n~ans for rokatin~ ~aid transducer about a rotational axis parallel to the axis of ~he barehole;
c) a ~heel rotated Ln synchronism with said transducer and having a plurality of teeth ~qually spaoed about its perip~ery;
d) a sensor spaoed Ln juxtapcsi~ion with said wheel for d~kecting ~he rate o~ mavement of said teeth past said sensor and ~or producing an electrical signal havin3 a plurality o~ pulses wit~ a repetition rate representative of the rate of mcvement of said tee~h Fast said sensor; and e) means responsive to said electrical signal for controlling said transducer to direct said F~S~s o~ acoustic energy~toward saicl borehole ~all at a repetition rate synchrom s~d with the rotational æpeed of said tran~duoer;
Pre~erably .said oontrol me3ns converts ~aid electrical signal to a tx~ r excitation signal hav ~ a p~l æ ~a~e synchroris~ i to the repeti~ion rate o~ the pulses comprising said electrical signal.
~ 3 203~fiO~
Desirably said oontrol means a~mprises:
(a) an oscill~tor for generat~ng said transducer excitation signal having a pulse rate that is a multiple N of the repetition rate of the pulses of said electrical signal, (b) me~ns fo~ dividing said transducer excitation signal by N; and .
(c) a detector ~or ccmp~r~ng the phase of said transducer excitation si~nal as di~ided by N with the phase ot`
said electrical signal to pxovide a phase error signal to said oscillator for synchronising said excitation 5ignal to said !". ' electrical 5ignal 50 that the rate at which said transducer directs p~lses of acoustic energy toward said borehole wall is synchronised with ~he rate of rctati~n of said transducer.
Preferably th~ means ~or rota~ing said transducer c~mprises a mokor ha~ing a plurali~y of ~paed variations during eac~ revolution.
In one embodi~ent the oQntrol mans comprises: :
(a3 an oscillator for produc mg a t~alsducer excitation si~nal having a E~se rat2 that is a mNl~iple N oR the pulse rate of said electrical si~nal; ~ : .
(b) a divide-by-N:coun~er that divides the pul æ r~te of :~
id trsnrducer e~ci~ation signal by said multiple N; and (c) a phase detector for OomparLng said electrical si~nal with ~ e ~ of sai~ ~ounter to provide a phase error signal for con~rolIing said oscillator so that the pulse r~e of said tre~ ducrr ex~i~ation si~nal is phase locked to the ~ul6e rate of said eleckrical signal whereby the rate a~ whi~h said txan~ducer dires~ acoustia ~nergy pulses tcward the borehole wall Ln synchron~ with the speed variakisns o~ said motor dh~ing each revolution ~ that said a ~ ic ~n~y pulses are directed from said ~ransduc~er ~t equall~ qpaced a~imuthal positions aboNt ~ e r~ta~ional aX~fi 0~ said ~ cer-:
~3~
In another O ~:
(a) the means for rokatLng the transducer ccmprises a motor for ro~ating the tLansduoer at a ;ra~e of R re~olutions per second with a plurality o~ aooeleration and deceleration cycles per revolution;
~ b) the wheel has T ~e~th ~ lly spaced about its ou~r periphery and is rotated in synchronism with said motor;
(c) the electrical signal p~oduced by tha sensor is a Rx~ hertz electrical signal repreæntative of the rate of movement o~ said teeth past said sensor ~ach second;
and said ~ further oomprises:
(d) a voltage contr~ll0d ~scillator ~r pr~ucing a P
hert2 trans~ucer excitation signal;
(e) a ocunter that divides said ~ransducer aYcitation signal by N to provide a P/N hertz ocun~er signal; an~
~ f) a phase de~ecto~ ~or comparing the phase o~ said RxT
hert3 electrical signal wi~h ~e ~hase o~ said P/N hertz si~nal to~provide a Fhase exror si~nal to con~rol the Yolta~e of said voltage contrDlled oscilla~r to cause said P hertz trar~ducer excitation signal to be phase locked tD :said ~xT hertz elec*rical slgnal;~so that ~aid trancducer excit~tion si~nal causes said tranc~Lcer~to dir0~t P/R acoustic energy Fulses toward the bcrehDl- wall at equall~ ~paos~ azimuthal ~ itions about said rotatlonal~axis for eadh rev~luti~n of said ~xansducer.
In ~his e~bcdi=:nt it is preferr0d th~t~
: a) R:r~pre#eY~:~ 6 rev~lutions per seoond, b) T represents 64 teeth, c) Rxr ~repre~ nts a 384 hertz electrical ~ignal, d3 P represents a 1536 hert2 transducer exci~a~ion : e1: N rep~esents a division o~ said txansducer e~citation si~nal by~4, : .
: ~: . , : -.
- 5 ~ O S
f3 PjN represents a 384 hertz cGunter signal, and g) P/R represents 256 accustic energy pulses per revolution of said transdu~er.
Reference is now made to ~he accompanyLng drawings Ln ~ich.
FIG. 1 illus*rates a bar.ehole logging tool with which the present invention may be uti.lized;
FIGSo 2~ 3 and 5 are electrical circuit di~gr~ms of the circuitry employed in the present invention for synchronising the generation of accu~tic energy pulses by the transmitting trans~ucer illustrated in FIG. 1 with the rotational speed o~ the trans~ucer as driven by the mo~or illustrated in FIG. 1; and FIG. 4 illustratRs a t~c-dlmensional light intensity ~ ion representing the display of acaustic reflection ~ignals recorde~ with ~he borehole 1 ~ tool o~ FIG. 1.
: Fo~ the purpose of illustratLng the type of borehole ~colstic logging system with ~ the apparabus o~ the present Lnvention nay be employ~d, a general de~cription~of the loggLng shc~n Ln FIG. 1 will be ~irst pYesen*ed, follownng which details of the apFsratus of:the present mvention will be described~
Referring now ~o FIGu 1, a bGrehole t~leviewer logging tool 11 is lcwered into bc~ehole 10 by means of a loggLng cable 12. IogqdnJ~tool 11 comprisss a transducer ~ss~m~ly 13 which acts as hoth a trans~Lttcr 14 an~ reoeiver 15 of acoustic energy.
m e beam of high ~requency accu~tic energy is xotated withLn ~he borehole to circNl æ ly scan the walls of the borehole. Such rotation is effected ~y ~ of n~or 16. While it is understood:that trenr~luc3r assembly 13 co~prises a æpara~e transmitt~r 14 and a reoei~ee lS, a sm gle trans~ucer acting bo~h as tlars~itter an~ receiver may ke utilized~ The transduce~
as~e~bly 13 is r ~ about the borehole axls by means o~ mokor :
, ::: :
:
, ; ; ,, , . ; , . . . . . .
:, :: . , .:, . . . . . . ..
.. : : .. . . .. ..
20~6~
16. m e frequency of the accus~ic en~ transmitted by way of beam path 21 toward the wall 22 of bor~lole 10 is determined by the pulser 17.
Logging tool 11 also incl~des a ~agnetometer 24, mounted for rotation wi~h the logging tool ll, which produces an output pulæ each time magnetic North is detected d~ring rotation. Such magnetometer output pulse is applied uphole to sawtooth sweep genexator 25 which pxovides a horizontal sweep signal to the horizontal deflection plates of an electron beam display device 26 for horizontally driving an electron beam across the face of display device 26.
Each horizontal sweep of the electron keam across the display device 26 is displaoed vertically ~rom the start of the sweep to ~he end of the s~eep in proportion to the v~rtical movement of the logging tool 11 within the borehole 10. Such displacement is proNided by means o~ a po~entiometer 27 which is coupled:by Plectm me~hanical li~kage 28 ~ a sheave 29 over which Ing cable:12 p~ssee. Vertical adnanoement of logging cable 12 alon~ the korehole a~ls ro~ates ~heave 29, such: rotation causing:eleotrcmech3ndcal linkage 28 to vary the location of the wi]~er arm on potenticmeter 27, thereby applyin3 ~o the vertical deflection pla~es of display device 25 a voltage which i~ :
;:prrpartio~al to the depth of the logging tool withun the borehole~ ~he resulting picture displayed on display device 26 is a series of side~by-side, substantially hor.iæ~ntal beams, the start of each beam traoe located at the vertical position on the : :
ace of the display ~evice where ~he preceding beam trao~
te~m~lted.
Reflected acoustic eneryy Eulses 23 æ e receiv~d by the ~ecelver 15 o~ tr~ns~uGer assembly 13, and signals representative ",:. :
of such reflections are appli~d to ~he Z~axis o~ display device 26 by ~ay of a si~nal amplifier 40 and detector 41, lccated : :
. , ,, , .. ,~. .. : :,,, : ": , . . ... . . . . . .
~0~6a~
F-5646-L ~.
downhole, and a pulse amplifier 34, g~te 35, and ~ r 36 located on the surface of the earth. Such input to the Z-input terminal of displa~ devîce 26 serv~s to int~sity m~dulate the electron beam in accordanoe wi~h the amplitudes of the refle~ion signals.
Ord ~ logging cabl~s are not suitable for transmission of high frequency signals, such as 2 mgahertæ, to the surface;
therefore, after bei~g amplified by signal amplifier 40, the refl~ction signals are applied to detector 41 which generates a lower ~r.equency ~ignal in ~he form o~ the envelope of the reflection signals. Such lower frequency signals, prefsrably in the range of 20-5n kilohertz, can be transmitted to the surface over ordlnary logging cable without a~preciable signal loss. The ou~put oP detestor 41 is a~plied to the input of pulse amplifier 34 by mRans of condu~tor 19.
Pulser 17 also prcvides an autput to a sync multivihrator 37, dslay monostable ~ lti ~ tor 38, a~d gating multivibrator;~.
39. The output o~ gating m~ltivi~rator 3g is an indication ~f the tIme period bebwaen transmltted acoustic energy pulses and : :
during which reflected acoustic energy pulses are expected ~ be receiv~d at receiver 15, such cutput being applied to gate 35 to allow reflecting signals to pass from pulse amplifier 34 through ~ate 35 and enhancer 36 to the m~dulating ~ t o~ display device 2~. :
~ hen pulser 17 generates an e~ci~atian pulse, a portion of this p~ cross-~eeds into re~eiv~r 15. A:Lso, ~hen a sync pulse is generatecl by pulsex 17 and sent uE*Iole via conductor 18, a portion of the ~æ crossf~ls ~to receiver c~nductor 19. rrO
E~ev~t ff~ese cro~;s-fe~d si~nals ~r~m intensity r~llat.~ng t~le :el~n bez~n o~ clis3play device 26, gate 35 is open only du~ing ~t portion of ~ime dur:in~ which reflected pulæs are expec~ed to be ~ frc:qn tha wall~; o~ t:he bQ~ole. Eac~ time a ~;ync . .
&
pulse is received by sync multivibr~dtor 37, it triggers into its unstable state for an output for a period of time almDst as long as the time period between transmitted acoustic pulses. At the same time that the output of sync multivi ~ator 37 goes positive, the delay moncstable multivibrator 38 is triggered into its uns~able stage for a period of tLme endin~ just prior to the anticipated arrival time of a reflected pulse at reoeiver 15. As :
the trailing edge of the outpu~ of delay multivi~rator 38 goes ~egative, the ga~ing monostable multivibrator 39 i5 triggered into its unstable state to generate a pcsitivergoing cutput, which triggers gating mwltiv;hrator 39 to provide a signal to gate 35 to allow passage therethrough of only those signals represen~ative of reflec~ed pulses. Therefore, only ~he envelopes of the reflection signals pa~s through gate 35 to enhancer 36.
HavLng now described a b~rehole televiewer logging system with which the present invention may be prackised, reference is made to FIGS. ~-5 along wi~h th~ following detailed description of the apparatus of the present invention for use in ~ controllin~ an aocustic tran~duoer to direct pulses of acoustic : ~ boward a ~or~hole ~all at a repetition rate synchronized with ffhe rotational s~peed o~ the transducer within ~he borehole.
Ref ~ firstly to FIG. 2, there is shown in block diagram form the ac~ustic tr ~ uoer synchronisation featuxe of the pres2nt inventi~n for use with the borehole televiewer loyging system of FIG. 1.
: A wheel 42 is rokated in synchronisation with the motor 16 ~ the transduce~ 13. m~ outer periphery of wheel 42 cantains i a~plur~lity of ex~lly spaoed ~ee~h. In juxtaposition with wheel :42 is a sensar 44 which detecks the mechanical rokation ~ wheel 42 by sens~ng the movement o~ ~eeth 43. Sensor 44 pre*erably ;:;
cc~prises an elex~ic coil wrapped around a magnatic core. AS
:.
, ~ , ' , '. !. ~ , . i. '. ' . .:
~5f~0~
each tooth passes ~he sensor 44, ~n electrical pulse is pro~lced ky sensor 44 and 6haped by pulse shaper 45. The rate at which such pulses are producsd is dependent ~pon motor speed ~uring each revolution which varies due to a number of acceleration ~nd decelera~ion cycles oorresponl~g to the number o~ poles present within the motor (i.e., a bwo pole moto:r having two acceleration and deceleration cycles p~r revolution). m ese pulses are utiliz~d by synchronisation unit 46 to control puls~er 17 so that the transducer 13 produces the same number of acoustic energy pulses ea~h revolution of motor 16 and ~he pul æ s are directed towand ~he borehole wall at equally spaced az.umuthal positions akout the rotational axis of the txansduc~r 13 regardless of motor speed ch3nges during each revolution.
~ eferring now to FIG. 3, ~here is shown in detail the ccmponents of the synchr~nisation unit 46 of F~G~ 2. Pulses from pulsQ shapar 45 are c3upled to the 1 input of phase lock locp 50 ha~ing a pbase detector 51, a low pass .filter 52 and a voltage :~
con~rolled oscilla~or (VCO) 53. In a pre~erred operation of the borehole loggin~ syst~m the mot~r 16 rota~es the transduc~r 13 at 6 revolutions per second and ~he wh0~1 42 empl~ys 64 teeth.
Iherefore, the sensor 44 and pulæ shaper 45 provide a 384 hert2 electrical signal to the 1 inpu~ of phase detector 51. The oscillator ~3 is vo~tage controlled to produced a 1536 hertz transducer excitation signal to ~he pulser 17. ~.his 1536 hertz transduoer e~citation signal is also coupled to a di~ide-~y-N
mter 54 which divides the 1536 hertz signal by 4 to provide a 384 hert2 signal to the 2 input oE phase detector 51a Phase differe~es between the paLr o~ 384 hRrtz signals input to phase detector 5~ æ e caused by motar speed variations that vary the phase of the 384 hertz electrical siynal fram sensor 44 and puls~
~haper 45. Dekector 51 provides a phase e~ror signal ~ ~e ~ tive of such Fhk~se dif~erences which passe~ thro~h low :
,~
~ o ~ Q ~
F-5646~L
pass filter 52 to control the vol~age applied to the oscillator 53. This voltage control causes oscillator 53 to vary its sutput to reduce the phase diffexence to zero so as to maintain phase lock within the lcop. m is output is also appli~d as the excitation signal to pulser 17 to cause pulser 17 to ~xcite trar~sducer 13 for the production of acoustic energy pulses.
Since this transducer excitation signal is derived from wheel 42 rotating with mo~or 1~ a~d transducer 13 by way of a phase lock loop, it is in synKhronism with transducer 13 rota~ion and causes transducer 13 to produce acoustic energy pulses at a repetition rate synchronised with mokor speed variations each revolution.
As~ordingly, an equal nu~ber o~ acoustic energy pulses are produced each rev~lution and they are azîmuthly egually spaced about the axls of ~Qr rotation despite the fact that the motor accelerates and decelerates a~ least twice ~i.e. for a dipole m~tor) durLng each revolution.
The importance of providing an exact number of acGustic ~ pulses for each trans~uGer rev~lution at equally spacad azimlthal positions can best be seen by re~erence to FIG. 4 which illustrates an aooustic aner~y re~lection signal being presented on display device 26 as a two dimensional light intensity function f(k, l~ where 1 is a row (line) number on the display k is a point (pixel) n~mber on a line. The total numb~r of lines in the im~ge is L and ~he tokal number of pixels p2r l.Lne ( ~ 1 t~ the tL~al number of c~lumns~ is K. The value of ~ ~t spa~ial coordinates (k, l) of FIG. 4 is e~ual to ~he ~mplitude (or time of arri~l~ of the re~ection si~nal received by the logging tcols rec~ er a~ azimuth k ~nd d~pkh l. This value f(k, 1) will determine ~he intensity o~ ~he pi~el (k~ l) on the display. The ima~e on ~he display consists of, for example, 256 horizontal lines }~ 256 pixels per line. '~his represents 256 scan line~ and 256 ev~nts per rev~lution of the transduoer. TbD
- :Ll 2Q3~0fi much or too little recorded reflection information during a given revolution will distort the 256 pixel image. Thus, it can be seen that synchronising the excitation, or pulsing, of the transducer to its rotation ~o that no mare or no less than the full display of 256 pixels is produced~sach revolution.
While a particular embcdim/nt of the present invention has been describ0d an~ shown in FIG. 3, it will be understood that the circ~ut components are merely repr~sent~tive of such particular embod~ment and various other types and values of circuit components may be utilized without departing fr~m the spirit and soope of the invention as se~ forth in the appended claims. In ac~7rbarce with such p~rticular embodiimnt, the phase detector 51, low pass ~i~ter 52 and VC0 53 may preferably be packaged in a single CD 4046 chip supplied ky ~ Q as shown in FIG. 5 with the circled numbers representing pin numkers. The following Table sets forth speci~.ic types ~nd values o~ circui*
elements for the enbodL~mnts o~ FIGS. 3 and ~.
Referense Desiqnation Description ~-~ Detec$or 51 CD 4046 ~RCA) Low Pass Filter 52 CD 4046 (RCA) VOO 53 CD 4046 (RCA) Divide-~y-Counter 54 CD 4520 (~CA) R~sisto~ 48 and 59 lOK
ResistQr 55 lOOK
Capacitor 49 0.047 uf Capacitor 57 0.1 uf , .
Capacit~r 58 820 pf ~V 5 vrc .
; , ;, , ~ , ", .
Claims (7)
1. A system for the acoustic logging of subsurface formations surrounding a borehole, comprising:
a) a transducer for directing pulses of acoustic energy toward the wall of said borehole and for receiving direct reflections of said acoustic energy from said borehole wall;
b) means for rotating said transducer about a rotational axis parallel to the axis of the borehole;
c) a wheel rotated in synchronism with said transducer and having a plurality of teeth equally spaced about its periphery;
d) a sensor spaced in juxtaposition with said wheel for detecting the rate of movement of said teeth past said sensor and for producing an electrical signal having a plurality of pulses with a repetition rate representative of the rate of movement of said teeth past said sensor; and e) means responsive to said electrical signal for controlling said transducer to direct said pulses of acoustic energy toward said borehole wall at a repetition rate synchronised with the rotational speed of said transducer;
a) a transducer for directing pulses of acoustic energy toward the wall of said borehole and for receiving direct reflections of said acoustic energy from said borehole wall;
b) means for rotating said transducer about a rotational axis parallel to the axis of the borehole;
c) a wheel rotated in synchronism with said transducer and having a plurality of teeth equally spaced about its periphery;
d) a sensor spaced in juxtaposition with said wheel for detecting the rate of movement of said teeth past said sensor and for producing an electrical signal having a plurality of pulses with a repetition rate representative of the rate of movement of said teeth past said sensor; and e) means responsive to said electrical signal for controlling said transducer to direct said pulses of acoustic energy toward said borehole wall at a repetition rate synchronised with the rotational speed of said transducer;
2. A system according to claim 1 wherein said control means converts said electrical signal to a transducer excitation signal having a pulse rate synchronised to the repetition rate of the pulses comprising said electrical signal.
3. A system according to claim 1 or 2 wherein said control means comprises:
(a) an oscillator for generating said transducer excitation signal having a pulse rate that is a multiple N of the repetition rate of the pulses of said electrical signal, (b) means for dividing said transducer excitation signal by N; and (c) a detector for comparing the phase of said transducer excitation signal as divided by N with the phase of said electrical signal to provide a phase error signal to said oscillator for synchronising said excitation signal to said electrical signal so that the rate at which said transducer directs pulses of acoustic energy toward said borehole wall is synchronised with the rate of rotation of said transducer.
(a) an oscillator for generating said transducer excitation signal having a pulse rate that is a multiple N of the repetition rate of the pulses of said electrical signal, (b) means for dividing said transducer excitation signal by N; and (c) a detector for comparing the phase of said transducer excitation signal as divided by N with the phase of said electrical signal to provide a phase error signal to said oscillator for synchronising said excitation signal to said electrical signal so that the rate at which said transducer directs pulses of acoustic energy toward said borehole wall is synchronised with the rate of rotation of said transducer.
4. A system according to claim 1, wherein the means for rotating said transducer comprises a motor having a plurality of speed variations during each revolution.
5. A system according to claim 4 wherein said control means comprises:
(a) an oscillator for producing a transducer excitation signal having a pulse rate that is a multiple N of the pulse rate of said electrical signal;
(b) a divide-by-N counter that divides the pulse rate of said transducer excitation signal by said multiple N; and (c) a phase detector for comparing said electrical signal with the output of said counter to provide a phase error signal for controlling said oscillator so that the pulse rate of said transducer excitation signal is phase locked to the pulse rate of said electrical signal whereby the rate at which said transducer directs acoustic energy pulses toward the borehole wall in synchronism with the speed variations of said motor during each revolution so that said acoustic energy pulses are directed from said transducer at equally spaced azimuthal positions about the rotational axis of said transducer.
(a) an oscillator for producing a transducer excitation signal having a pulse rate that is a multiple N of the pulse rate of said electrical signal;
(b) a divide-by-N counter that divides the pulse rate of said transducer excitation signal by said multiple N; and (c) a phase detector for comparing said electrical signal with the output of said counter to provide a phase error signal for controlling said oscillator so that the pulse rate of said transducer excitation signal is phase locked to the pulse rate of said electrical signal whereby the rate at which said transducer directs acoustic energy pulses toward the borehole wall in synchronism with the speed variations of said motor during each revolution so that said acoustic energy pulses are directed from said transducer at equally spaced azimuthal positions about the rotational axis of said transducer.
6. A system according to claim 1, wherein (a) the means for rotating the transducer comprises a motor for rotating the transducer at a rate of R revolutions per second with a plurality of acceleration and deceleration cycles per revolution;
(b) the wheel has T teeth equally spaced about its outer periphery and is rotated in synchronism with said motor;
(c) the electrical signal produced by the sensor is a RxT hertz electrical signal representative of the rate of movement of said teeth past said sensor each second;
said system further comprising (d) a voltage controlled oscillator for producing a P
hertz transducer excitation signal;
(e) a counter that divides said transducer excitation signal by N to provide a P/N hertz counter signal; and (f) a phase detector for comparing the phase of said RxT
hertz electrical signal with the phase of said P/N hertz signal to provide a phase error signal to control the voltage of said voltage controlled oscillator to cause said P hertz transducer excitation signal to be phase locked to said RxT hertz electrical signal so that said transducer excitation signal causes said transducer to direct P/R acoustic energy pulses toward the borehole wall at equally spaced azimuthal positions about said rotational axis for each revolution of said transducer.
(b) the wheel has T teeth equally spaced about its outer periphery and is rotated in synchronism with said motor;
(c) the electrical signal produced by the sensor is a RxT hertz electrical signal representative of the rate of movement of said teeth past said sensor each second;
said system further comprising (d) a voltage controlled oscillator for producing a P
hertz transducer excitation signal;
(e) a counter that divides said transducer excitation signal by N to provide a P/N hertz counter signal; and (f) a phase detector for comparing the phase of said RxT
hertz electrical signal with the phase of said P/N hertz signal to provide a phase error signal to control the voltage of said voltage controlled oscillator to cause said P hertz transducer excitation signal to be phase locked to said RxT hertz electrical signal so that said transducer excitation signal causes said transducer to direct P/R acoustic energy pulses toward the borehole wall at equally spaced azimuthal positions about said rotational axis for each revolution of said transducer.
7. A system according to claim 6 wherein:
a) R represents 6 revolutions per second, b) T represents 64 teeth, c) RxT represents a 384 hertz electrical signal, d) P represents a 1536 hertz transducer excitation signal, e) N represents a division of said transducer excitation signal by 4, f) P/N represents a 384 hertz counter signal, and g) P/R represents 256 acoustic energy pulses per revolution of said transducer.
a) R represents 6 revolutions per second, b) T represents 64 teeth, c) RxT represents a 384 hertz electrical signal, d) P represents a 1536 hertz transducer excitation signal, e) N represents a division of said transducer excitation signal by 4, f) P/N represents a 384 hertz counter signal, and g) P/R represents 256 acoustic energy pulses per revolution of said transducer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US475,547 | 1990-02-06 | ||
| US07/475,547 US4969128A (en) | 1990-02-06 | 1990-02-06 | Borehole acoustic logging system having synchronization |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2035606A1 true CA2035606A1 (en) | 1991-08-07 |
Family
ID=23888060
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002035606A Abandoned CA2035606A1 (en) | 1990-02-06 | 1991-02-04 | Borehole acoustic logging system having synchronization of acoustic transducer rotation and output |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4969128A (en) |
| EP (1) | EP0441546A2 (en) |
| AU (1) | AU7085291A (en) |
| CA (1) | CA2035606A1 (en) |
| NO (1) | NO910441L (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5519668A (en) * | 1994-05-26 | 1996-05-21 | Schlumberger Technology Corporation | Methods and devices for real-time formation imaging through measurement while drilling telemetry |
| US8270250B2 (en) * | 2006-01-03 | 2012-09-18 | Halliburton Energy Services, Inc. | Programmable data acquisition for tubular objects |
| US8903577B2 (en) | 2009-10-30 | 2014-12-02 | Lsi Industries, Inc. | Traction system for electrically powered vehicles |
| US8604709B2 (en) | 2007-07-31 | 2013-12-10 | Lsi Industries, Inc. | Methods and systems for controlling electrical power to DC loads |
| US7598683B1 (en) | 2007-07-31 | 2009-10-06 | Lsi Industries, Inc. | Control of light intensity using pulses of a fixed duration and frequency |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3369626A (en) * | 1965-10-23 | 1968-02-20 | Mobil Oil Corp | Methods of and apparatus for producing a visual record of physical conditions of materials traversed by a borehole |
| US3718204A (en) * | 1971-01-18 | 1973-02-27 | Mobil Oil Corp | Display of borehole wall configuration |
| US3728672A (en) * | 1971-08-09 | 1973-04-17 | Mobil Oil Corp | Method and apparatus for logging the characteristics of materials forming the walls of a borehole |
| US4575677A (en) * | 1984-05-25 | 1986-03-11 | Mobil Oil Corporation | Motor speed detector |
| US4736348A (en) * | 1986-08-21 | 1988-04-05 | Mobil Oil Corporation | Method and apparatus for logging the characteristics of materials forming the walls of a borehole |
| US4780862A (en) * | 1986-11-17 | 1988-10-25 | Shell Oil Company | Borehole televiewer |
| US4837753A (en) * | 1987-04-10 | 1989-06-06 | Amoco Corporation | Method and apparatus for logging a borehole |
| US4876672A (en) * | 1988-03-01 | 1989-10-24 | Atlantic Richfield Company | Ultrasonic logging tool with rotating exposed transducer |
-
1990
- 1990-02-06 US US07/475,547 patent/US4969128A/en not_active Expired - Fee Related
-
1991
- 1991-02-01 EP EP91300827A patent/EP0441546A2/en not_active Withdrawn
- 1991-02-04 CA CA002035606A patent/CA2035606A1/en not_active Abandoned
- 1991-02-05 NO NO91910441A patent/NO910441L/en unknown
- 1991-02-08 AU AU70852/91A patent/AU7085291A/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| AU7085291A (en) | 1991-08-08 |
| NO910441L (en) | 1991-08-07 |
| US4969128A (en) | 1990-11-06 |
| NO910441D0 (en) | 1991-02-05 |
| EP0441546A2 (en) | 1991-08-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3668619A (en) | Three-dimensional presentation of borehole logging data | |
| EP0031989B1 (en) | Shear wave acoustic well logging tool | |
| US3265151A (en) | Means and techniques useful in establishing quality of cement bonds in cased boreholes | |
| CA1316588C (en) | Method and apparatus for logging a borehole | |
| CA1281117C (en) | Method for driving a bender-type transmitter of a borehole logging tool to sequentially produce acoustic compressional and tube waves | |
| US2648056A (en) | Well logging method and apparatus | |
| US4780858A (en) | Borehole televiewer mudcake monitor | |
| CA2035606A1 (en) | Borehole acoustic logging system having synchronization of acoustic transducer rotation and output | |
| US3728672A (en) | Method and apparatus for logging the characteristics of materials forming the walls of a borehole | |
| US3553640A (en) | System for obtaining uniform presentation of acoustic well logging data | |
| USRE25928E (en) | Seismic well logging data display | |
| US3093810A (en) | Seismic well logging data display | |
| US3390377A (en) | Acoustical well logging methods and apparatus | |
| US3434568A (en) | Three-dimensional display of borehole logs | |
| US4172250A (en) | Acoustic well logging with threshold adjustment | |
| US3835953A (en) | Acoustic caliper logging | |
| US4542488A (en) | Method and system for producing a PPI display | |
| US4691307A (en) | AGC circuit for televiewer | |
| US4897646A (en) | Method and apparatus for reducing the effective bandwidth of ultrasonic waveform for transmission over a logging cable | |
| GB1116406A (en) | Method for detecting fractures in a formation penetrated by a borehole | |
| GB1292993A (en) | System for displaying time information in acoustic well logging system | |
| CA1149970A (en) | Method and apparatus for measuring neutron characteristics of material surrounding a borehole | |
| US4984221A (en) | Borehole acoustic logging system having automatic reflection signal level control | |
| US4904956A (en) | Linear digital frequency sweep synthesizer | |
| US3371313A (en) | Method and apparatus for producing a reflectivity log of formations traversed by a borehole |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |