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Патент USA US3086178

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April 16, 1963
G. o. BUCKNER, JR
3,086,168
SYNTHETIC ARRAY LOGGTNG SYSTEM AND METHOD
IN VEN TOR.
fT/G. Z.
BY
“Urge/<3
April 16, 1963
3,086,168
G. O. BUCKNER, JR
SYNTHETIC ARRAY I_.OGGING SYSTEM AND METHOD
Filed March 50, 1959 '
2 Sheets-Sheet 2
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INVENTOR.
BY í» ¿a
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United States Patent 0
3,086,l58
Patented Apr. 16, 1963
2
1
may be accomplished by changing the gain in an ampli
lier circuit, (2) that the effect of a change in polarity
3,086,168
SYNTHETIC ARRAY LOGGING SYSTEM
may be accomplished by changing the number of ampli~
AND METHÜD
fiers through which a signal undergoes a 180° phase
Guy 0. Buckner, Ir., Houston, Tex., assigner to Halli
change and (3) that the effect of a change in spacing
burton Company, a corporation oi Delaware
may be accomplished by changing the relative positions
Filed Mar. 3i), 1959, Ser. No. 802,765
of reproducing heads which reproduce the separate data
19 Claims. (Cl. S24-»Q
derived individually from the various receiver coils.
Another object of the present invention is to provide
The present invention relates to improved means and
techniques whereby various logs, of for example, the 10 improved means and techniques whereby characteristics
of earth formations may be indicated in the form of a
type produced in a multi coil induction logging system
log without movement of a logging tool.
may be synthesized, with the various logs so synthesized,
The features of the present invention which are be
reflecting such changes, as for example, change in coil
spacing, change in number of coil turns or turns ratio,
lieved to be novel are set forth with particularity in the
change in receiving coil polarity and other factors which 15 appended claims. This invention itself, both as to its
organization and manner of operation, »together with
enter into a multi coil induction logging system.
further objects and advantages thereof, may be best un
The term “multi coil induction logging system” has
derstood by reference to the following description taken
general reference to logging systems wherein a plurality
in connection with the accompanying drawings in which:
of transmitter coils and/or a plurality of receiver coils
are mounted in a logging tool for indicating either con
ductivity or resistivity of formations traversed by a bore
hole in which the logging tool is moved with the trans
mitter coil or coils inducing voltages in the formations,
and the receiver coil or coils having induced therein
FIGURE 1 illustrates a new system in accordance with
the present invention for recording separately the results
of a plurality of two coil logging systems.
FIGURE 2 also embodying features of the present in
vention illustrates one manner in which a composite log
voltages produced by the eddy currents in the forma 25 may be produced -from the data recorded in the system
tions.
shown in FIGURE l.
FIGURE 3 illustrates another system embodying fea
Thus, in some commercial multi coil logging systems
tures of the present invention.
there may be a plurality of transmitter coils spaced from
FIGURE 4 illustrtates the spacing and phase rela
each other and connected electrically to induce voltages
of opposite polarity in the formations; and simulta 30 tions of coils in a multi coil logging system assimilated
by the system in FIGURES l and 2.
neously therewith, there may be a plurality of receiver
FIGURES 5, 6 and 7 are helpful in explaining the
coils spaced from each other and connected electrically
manner in which the logging system shown in FIGURE
to produce the difference in their induced voltages with
4 is synthesized in FIGURES l and 2.
such difference serving as a measure of the formation con
35
Referring to FIGURE 1, there is included a single
ductivity or resistance.
transmitter coil Ii) and a plurality of receiver coils IZ,
Some disadvantages of such multi coil logging system
13, 14 and IS, all in axially spaced relationship with their
is that the tool containing the various coils is expen
axes, coaxial with the axis of the bore Vhole 16, and
sive to manufacture, and after manufacture, the same
cannot be changed without involving substantial recon 40 the same are considered to be mounted in a logging tool
or sonde which is caused to move in the bore hole. ln
struction. Furthermore, it is not economically feasible
formation in the form of voltages induced in the re~
to run induction logs using a plurality of logging tools
ceiver coils 12-'15 are recorded separately or in
in which the number of coils, their spacing and the num~
dividually in corresponding individual channels I8,
ber of turns on each are different to satisfy customer
demands in various oil producing areas.
45 19, 20 and 21 respectively on, for example, a mag~
In accordance with an important feature of the pres
ent invention the results of any multi coil logging sys
tem -may be assimilated by the proper use of data, taken
in a single logging run, by a logging tool containing a
single transmitter coil and a plurality of receiver coils 50
having their outputs recorded individually.
It is therefore an object of the present invention to
provide improved means and techniques for achieving
the results indicated in the preceding paragraph.
netizable tape 22 which is driven synchronously or in
timed relationship with the logging tool containing
coils 12-15 using conventional means for that purpose
represented by the synchro tie 24 in FIGURE l.
As illustrated, the recording medium 22 is driven in
timed relationship with, for example, a pulley 26
over which the logging line 28 is reeled. Also, suit
able means involving such synchro tie 24 is provided
to effect a recording in channel 29 in the form of, for
In the furtherance of such object, a further object 55 example, coded pulses representative of the depth of
of the present invention is to provide a logging tool in
a predetermined reference plane in the logging tool as, for
example, a plane midway between coil I0 for reasons
which several two coil induction logs with various spac
ings between the coils is obtained in a single run through
explained later.
For example, the coils 12, 13, 14 and 15 may be spaced
the bore hole.
Another object of the present invention is to provide 60 respectively 30, 40, 50 and 60 inches from the transmit
means and techniques whereby the data obtained as in
-ter coil 10 and for purposes of reference the various
channels through which the corresponding signals pass
dicated in the preceding paragraph is combined to as
are designated with corresponding numbers as indicated
similate the results of -a multi coil log using the con
in the drawings with the designation, T_S. meaning trans
cept that (l) the effect of a change in coil turn ratio
essaies
3
¿Il
mission system and the designation RC. meaning record
ing channel.
ners in which the recordings made on the medium
in
FÈGURE l may be combined to produce the dii’ferent
effects enumerated above in a logr represented by the log
which
'l'he receives
voltage induced
its current
directly
from by
oscillator
transmitter
Sil, into
coil cor
responding receiver coils ELLES, due to the mutual in
ductance, oftentimes referred to as the quadrature com
ponent, is balanced out by corresponding balancing means
MA, lÉiA, lift-A and ' ' s.
rthese balancing means may
each comprise a transformer having some of the trans~
mitter coil current flowing through its primary winding
for inducing a balancing or bucking voltage in the sec
5
S3' on a second recording medium
in FIGURE 2 the original tape 22 which may, for ex
ample, comprise a magnetizable tape is driven in timed
or synchronous relationship with respect to tape or film
fill, using suitable means for that purpose. For example,
tape 22 and hlm 5l may be driven by a common driving
.means S5 at the same or different speeds, preferably how
ever such that the lilm 5l moves slower than
22,
ondary winding thereof to balance out the corresponding
but however in corresponding relationsáp therewith; and
quadrature component induced in corresponding receiver
coils so that substantially only the socalled in phase
or resistivity component, ic., that component which is
due substantially entirely to the eddy currents in the
formation is applied to the corresponding transmission
the depth recording 29 previously made on tane
in
the form of coded pulses are reproduced by r‘oroducing
means 57 and applied to suitable depth recording rnc-"ni
Sii for photographing onto film Si the series of indicia
channels MB, lSB,
by depth recordings are thus made using a printing proc
and 35B, each having their output
representing predetermined depths. Processes whcrc~
ess wherein the indicia on a prerecorded negative film is
circuits coupled to the mixer stage 32 which in turn, has
optically printed on tape 5l! are well-known and have
its output applied to the inner conductor
of the log
been used for this purpose.
ging line 2.8.
The recording in channel i8 produces variations in
The transmission channels lâh-“53, for these purposes
the reproducing head 6d and such variations are ampli
may include subcarriers of dirierent frequencies, which
lied in amplifier 63 containing a single amplifying device
are modulated by corresponding resistivity components
and such subcarriers may be applied to the mixer stage 25 before being applied to the potentiometer type resistance
65 having one of its terminals grounded.
32. which may include a carrier frequency modulated by
A second reproducing head 66 cooperating with the
the individual subcarriers.
same channel i8, i.e., 3() inch channel, has the variations
These individual subcarriers are detected and dernodu~
produced therein applied to a single amplifier stage 68
lated at the surface using suitable equipment for that pur
pose at the surface, such equipment at the surface being 30 containing only one amplifying device and the output
thereof is applied to the potentiometer type resistance
represented, for purposes of simplicity as corresponding
oh having one of its terminals grounded.
filtering networks ElZC, lSC, 14C and lSC and recording
A reproducing head oi reproduces the variations or
channels lil), lBD, MD and 115D having their individual
outputs applied to corresponding recording heads lZlâ,
13E, ME and llSE for producing the corresponding 1n
phase or resistivity recordings in channels ifi-2l.
The oscillator 3d operates at a frequency of, for ex
ample7 2() kilocycles per second. in some cases it is de
signal recorded in the 40 inch channel i9 and the same
is applied successively to the two amplifying stages 64
and 67, each containing a single amplifying device be
fore being applied to the potentiometer type resistance ‘70
having one of its terminals grounded.
The voltages thus appearing on each of the taps 79A,
in response to a different frequency and in such cases the 40 65A and 69A. of corresponding resistances 7d, 65 and
sired, as explained later, to make simultaneous recordings
69 are mixed in the mixer and converter stage 72 which
system previously described in FEGURE 1 is supple
has a unidirectional output applied to recording means
mented by the equipment indicated in dotted lines to
73 to record the log 5@ which indicates the resultant of
produce simultaneously recordings 3d, 3‘), dit and di also
the three voltages appearing on these three taps.
indicated in dotted lines. in this latter instance the
It will be seen that the logl 5€) may be altered in many
oscillator 44 operating at a frequency different from the
frequency of oscillator 3d »is connected to transmitter coil 45 dilferent ways to assimilate various conditions.
First, it should be noted that the phase of the voltage
44B which is spaced, for example, live inches below trans
applied to mixer '72 depends on the number of stages
mitter coil itl and as explained previously the quadrature
through which the signal has been previously amplified, it
component is balanced out also using means for that
being remembered that a signal changes its phase i8()
purpose as indicated above. When two oscillating sources
are used, then preferably iiltering means indicated at 50 degrees every time the signal is amplified in a vacuum
tube amplifier. Thus, in the exempliiication in FIGURE
BEA and 44A in series respectively with sources 3G and
2 the phase of the signal derived from track or channel
4d- are provided. When source d4 is of higher frequency
i9 is reversed with respect to the phase of the signal de
than source 3d then the band pass characteristics of the
rived in either reproducing head oil or 66. Thus, in
filters 30A, 44A are as indicated in the rectangles repre
senting the same, it being noted that 'filter ESA passes 55 effect, the log Sil represents as an integral part thereof
only the frequency corresponding to source 3d and that
a condition wherein the receiver coils l2 and 13 are so
iilter 44A passes only the frequency corresponding to
connected in a multi log system with the outputs of such
source dd and that these iilters each attenuate greatly
coils l2 and i3 bucking each other, i.e., with their out
the frequency of the other source.
puts in 180 degree phase relationship. Thus the number
For purposes of simplifying FIGURE l, the same only 60 of amplifying stages comprise a means whereby the po
shows the association of receiver coil l5 with the supple
larity of a coil may be changed.
mentary 65 inch transmission system ESSE (correspond
Secondly, it should be noted that the positions of the
ing to lSB) and the 65 inch recording channel ÍLS’DD
adjustable taps 76A, 65A and 69A determine the ampli
(corresponding to ESD) but it is understood that the
tude of corresponding signals applied to mixer stage 72.
transmission systems and recording channels associated 65 This means that the voltage induced in each receiver
with the other three coils i2, i3, and M follow this same
coil may be effectively changed with respect to its iniiu
pattern.
ence on the shape of log Sil, and by the same token, the
number of turns on each coil may thus be altered since
It Will be thus understood that the recordings in chan
from theoretical considerations explained more fully in
nels 33, 39,
and ¿il are recordings of the in phase or
resistivity component developed substantially entirely by 70 by copending application Serial No. 798,624, filed March
the formation eddy currents produced at a frequency es
1:1, 1959, the voltage in a receiver coil varies generally
tablished by the frequency of oscillator 4.4, ie., a fre
in direct proportion to the number of turns comprising
quency different from the frequency that causes the other
the receiver coil. Thus, the adjustable taps 70A, 65A
group of recordings in channels ’i3-2l.
and 69A exemplify a means whereby the number of turns
FIG RE 2 illustrates one of the many did-ferent man 75 in an assimilated multi coil induction logging systems
3,086,168
d
may be changed with respect to vtheir effect on the shape
of log 50, and by the same token, the turns ratio of two
different receiver coils in the assimilated or synthesized
responses are combined with the response obtained in
FIGURE 5 to obtain the net response in FIGURE 4.
tween any two coils may be effectively changed with re
As indicated previously, the response of the auxiliary
v30 inch auxiliary pairs may be subtracted from the re
sponse of the main 40 inch pair either by reversing the
leads to the coils as in FIGURE 4 or by passing the
spect to their influence on the shape of log Sil. This is
voltage of the 30 inch pairs 81, $3 and 82, 80 through
log.
Thirdly, it should be noted that the relative spacing be
one more stage of amplification than the voltage derived
yfrom the 40 inch pair 80, S1 to obtain a 180 degree phase
the reproducing heads 6d, 61 and 66, a closer spacing of
the same corresponding to a closer spacing of the coils 10 relationship before combining the signals in an adding or
mixing circuit 72 (FIGURE 2).
being assimilated in a synthesized multi coil logging
Thus, in accomplishing this result it is noted that the
system. The means whereby the reproducing heads 6d,
response of the 40 inch pair 80, 81 corresponding to the
61, 66 may be thus adjusted along corresponding chan
40 inch spaced pair 10, 13 in FIGURE 1 and the cor
nels 18, 19 and 18 is represented by the corresponding
adjusting means 60A, 61A and 66A and it will be under 15 responding recording 19 in FIGURE 2 and also the re
spouse of the 3G inch pairs 81, 83 and 82, 89 correspond
stood that the same exemplifies a means whereby the as
ing to recording 18 are played back in FIGURE 2 at dif
similated coils may be adjustably spaced.
ferent depths, i.e., the reproducing heads 60, 61 and 66
-Fourth1y, it should be noted that the reference point
are not aligned in a direction perpendicular or transverse
of measurement may also be adjusted with respect to the
center of transmitter coil 10 by adjustment of reproduc 20 to the direction of tape movement indicated by arrow
22A.
ing head 57 along the “depth” channel 29, the means for
In other words, the net voltage recorded in FIGURE 2
adjusting the same being indicated at 57A; and in such
corresponds vto a recording of the 40 inch spaced pair less
case, assuming the tape drive means 5S to be ineffective
(because of amplifier 67) the sum of the 30 inch record
under this condition as contemplated, the relative posi
tions of the tape 22 and nlm Sil may be adjusted. Thus 25 ing 1S produced by reproducing means 60 located at a
position corresponding to 35 inches a‘bove the 40L inch
the adjusting means 57A constitutes a means whereby
spaced pair and the 30 inch recording 18 produced by
the reference point in a bore hole may be adjusted in the
reproducing means 66 located at a position corresponding
assimilated multi coil logging system.
to 35 inches -below the Át() inch spaced pair. Stated also
It should also be noted that each one of these four
in different words, reproducing means 61 reproduces the
adjustments described in the preceding four paragraphs
condition shown in FIGURE 5, reproducing means 60
are and may be made independently of each other.
reproduces the condition shown in FIGURE 7 and re
Instead of adding all of the voltages from taps 76A,
producing means 66 reproduces the condition illustrated
65A and 69A in the mixer stage 72 and producing a single
in FIGURE 6, and the proper subtraction corresponding
composite log 5d, as shown in FIGURE 2, it is con
templated also that these voltages may be recorded sep 35 to the bucking relationship of the coils shown in FIGURE
accomplished by adjustment of the relative positions of
arately on a iilm or tape when it is desired to produce a
visual representation of the same.
The above description is perhaps made clearer by ref
5 is accomplished «by providing the single additional am
pliiier 67 in FIGURE 2.
The dimension of 35 inches above and 35 inches below
is referenced with respect to a reference line or plane mid
erence to FIGURE 4 illustrating a multi coil logging
40 way -between the main coils 80 and 81 corresponding to
system which is desired to be assimilated or synthesized
coils 1o and 13 in FIGURE 1, and corresponds to one
using the arrangements shown in FIGURES 1 and 2.
half the distance between main coils 80 and 81, i.e., 20
FIGURE 4 illustrates a multi coil logging system which
inches plus one-half the distance between coils 80 and 82
in essence includes the main pair of coils, i.e., main
transmitter coil 8d and main receiver coil 81 spaced 4G 45 i.e., l5 inches, and correspondingly one-half the distance
between coils S1 and 83 i.e., l5 inches. In some cases it
inches apart, with auxiliary 30 inch spaced coils d2 and
may be desired to produce indications with respect to a
S3 above and below, coil 82 being a receiver coil and
different reference line or .plane other than midway be
coil 83 being a transmitter coil. It is noted that trans
tween main coils 8€) and 81 as in a system previously
mitter coils 30 and S3 are connected in series with oscil
indicated wherein the individual voltages on taps 70A,
lator 84 for producing flux of opposite polarity in the
65A and @A are recorded separately in which case the
formations. Also, receiver coils S1 and S2 are connected
reproducing head 57 (FIGURE 2) may be adjusted to a
in bucking relationship so that suitable voltage indicating
different position with respect to reproducing head 60
means represented yfor purposes of illustration as volt
and if desired reproducing heads 60 and 66 may be also
meter 85 indicates the difference in the in phase or re
sistivity component.
readjusted. Thus, `as shown, the tape 51 is controlled by
the depth pickup head 57 such that the output recording
The signals induced or received by the 30 inch coils
or log indicates depth in a fixed relation to the original
83 and 82 respectively are small in comparison to cor
recording on tape 22. When, as described above, the
responding signals induced by the main coils d@ and 81
original recording on tape or film 22 is made with rc
respectively. This arrangement may be used for good
thin bed definition, with the results obtained being in 60 spect to the center of coil 10, the depth reference may be
changed in FIGURE 2 with reproducing heads misaligned
fluenced only to a small extent by bore hole mud.
by 2O inches, i.e., reproducing head 57 is moved up in
An analysis of the arrangement shown in FIGURE 4
FIGURE 2 «a distance corresponding to a 20 inch distance
reveals that essentially the net response is that due to the
in the bore hole with respect to reproducing head 60 with
sum of the response of the main 40 inch pair and the two
30 inch pair as indicated in FIGURES 5, 6 and 7, it 65 the relative positions of heads 60, 61 and 66 remaining
being noted that the voltage induced in auxiliary receiver
unchanged.
As indicated previously, the formations may have in
coil S2 by auxiliary transmitter coil 33 is small in com
duced therein currents of two different frequencies estab
parison to the voltages produced in FIGURES 5-7.
lished by oscillators 30 and 44 in FIGURE 1 for study
The response of the arrangement shown in FIGURE 4
is thus a summation of the responses of FIGURES 5, 6 70 ing or indicating the effect of frequency in a multi coil
logging system using means and techniques described
and 7. It is considered substantially immaterial as to
above or in some cases for studying `or indicating the ef
whether the coil pair of FIGURE 6 and/ or the coil pair
fects of two `asymmetrically spaced transmitter and re
of FIGURE 7 is a part of the logging sonde since the
ceiver coils in a multi coil system assuming that in this
same may be considered to be located at different dis
tances and corrected for depth before their respective 75 last instance that the frequencies are sufficiently close to
3,086,168
7
tl
gether and produce substantially the same eftects in the
formations. Also, by using different transmitting coils
operating at dii’ierent frequencies the number of receiver
coils may be reduced, i.e., the addition of the single trans
movable arms are in their upper positions, a presentation
mitter coil
has the effect of the addition of four more
receiver coils, each `spaced five inches with respect to cor
responding receiver coils 12, 13, 1d and 15.
FÍGURE 3 illustrates a modified system in simplified
form for producing a visual presentation of the character
illustrated at 9d and 91 on a cathode ray tube or scope
92 with, for example, the logging tool remaining station
ary in the -bore hole or traveling at a relatively small
speed in comparison to the rate at which the series of
switches 12S, 13S, 14S and 15S are operated while si
exemplified at 91A is produced by the scope 92. The
persistency of the screen of the scope 92 is made suf
ficiently long so that an observer may see both presenta
tions 9ÜA and 91A simultaneously on the same screen
for comparison purposes.
For these purposes, the taps 12T-1ST are so adjusted
hat the portion S’tlA is substantially a horizontal straight
ine, the other portion 9MB, in the form of a Calibrating
ulse is the same in both cases and is produced when and
s the tap 95 engages the target electrode 101, the same
eing accomplished irrespective of the position of switches
t28-15S. The other variation 91A which is due .to the
character of the formations being observed, studied or
multaneously scanning of a conductor or electron beam
indicated is thus indicated with respect to the pre-estab
lished horizontal portion 90A.
indicated at 95 in the direction indicated by the double
arrow 94 progresses at a relatively high rate.
The height of the calibration pulse 90B corresponds
The same oscillator Sti, oscillator coil Il@ and balancing
to a predetermined conductivity. In accordance with at
means 12A-15A are associated with each receiver coil
least theoretical considerations which are detailed in my
l2, 13, 14, 15 in the same manner as in FlGURE l. ln 20 above mentioned copending application Serial No. 798,
this case, however, the oscillator 3h is also connected in
624 the in phase or resistivity component of the voltage
series with a voltage dividing circuit including the serially
induced in the receiver coils as a result of eddy currents
connected resistances 97 and 98, the resistance 98 having
a series of taps 12T, 13T, 14T and 15T, adjustable for
calibration purposes, which are connected to a corre
sponding stationary contact of single pole, single throw
switches `12S-15S respectively. The other stationary con
tact of these switches having applied thereto respectively
flowing in a homogeneous formation varies generally in
inverse proportion to their spacing from the transmitter
coil. Thus to produce the straight line portion 90A,
the gains of the receiver coil amplifier circuits are ad
justed accordingly; and this in general involves the ad
justment of taps 12T~15T and adjustment of taps on re~
the in phase or resistivity component of the coils 1.2-1.5.
sistances 12W-15W. Thus, in homogeneous formation,
The movable contacts of switches 12S-15S are ganged 30 the presentation 91A would also be a straight line corre
as indicated by the dotted line 98 for simultaneous move
sponding to line 96A and coinciding therewith. Any
ment by, for example, a relay coil 99 energized by a
variations in homogeneity are thus indicated by devia
pulse source 100 for recurrently operating the series of
tions of trace 911A from being parallel with the straight
switches 12S-15S, which art used for calibration.
line 90A. Such deviations vary linearly with formation
The movable switch arms are connected respectively
conductivity, the particular magnitude of which can be
to corresponding amplifying means 12V-15V located in
ascertained by interpolation using a linear scale factor
the bore hole which thus alternately amplify the output
established by the Calibrating pulse 90B.
of the receiver coils and corresponding adjusted voltages
Thus, in FIGURE 3 the straight line 9tlA may be con
established by taps lZT-lST.
sidered to be a graph in which the ordinates are apparent
The output of amplifying means 12V-15V is applied to
conductivity and the abscissae are distances measured
a corresponding series of potentiometer resistances 12W
along the bore hole; and this straight line represents con
15W across which corresponding signals are developed.
ditions in a homogeneous formation while curve 91A
The A.C. voltages appearing on the adjustable taps on
represents conditions in non-homogeneous formations.
these resistances are converted into a unidirectional volt
The calibration pulse 9MB corresponds to a predetermined
age in corresponding converters 12Y-15Y -which have 45 voltage applied to target electrode 101 based on meas
their unidirectional outputs connected to different points
urements or theoretical considerations and may, for ex
The taps on resistances 12W-15W are
ample, correspond to approximately a voltage represent
adjusted so that the voltages on each (in a homogeneous
formation condition) are progressively higher in that or
ing 50 millivolts for a formation conductivity of l() milli
on resistance 107.
ohms per meter.
der. For example, the gain setting of the tap or resist 50
The system shown in FIGURE 3 may also be alter
ance 13W is higher than the setting of the tap on resist
nately used in conjunction with the recording 22 in which
ance 12W.
case the reproduced outputs of channels 18, 19, 20 and
The electrical connector 95 indicated as a resistance
21 are applied respectively to corresponding upper sta
tap is recurrently swept over such resistance 107 and a
tionary contacts of switches 12S-15S as indicated in FIG
target electrode 101 by sweep producing means indicated 55 URE. 3. In such case the reproducing heads for these
at 103 which may, for example, be a sixty-cycle syn
chronous motor.
channels are all positioned with respect to tape move
ment to provide alignment with respect to a common
This target electrode 101, for purposes of providing a
depth reference of the subsurface tool and the tape 22
moves at a relatively small speed compared to the high
established by converting in converter 104 an `A.‘C. volt 60 rate at which the scanning indicated at itil` occurs; and
age derived from the oscillator Btl.
also, of course, the same patterns 96B and 90A may be
The unidirectional voltage signal thus developed on
produced using in this instance an oscillator comparable
the tap 95 during its recurrent movement modulates a
to oscillator 3h in FIGURE 3.
carrier in modulator stage 1h15 having its modulated out
While the particular embodiments of the present in
put transferred over logging line 28 to surface equipment 65 vention have been shown and described, it will be obvi
which includes the demodulator 166, the unidirectional
ous to those skilled in the art that changes and modifi
output of which is applied to the Y deflection axis of the
cations may be made without departing from this inven
scope 92. The time base sweep of such scope is syn
tion in its broader aspects and, therefore, the aim in the
chronized by a synchronizing pulse 90B which operates
appended claims is to cover all such changes and modifi
the sweep means 103 in the bore hole so that such time 70 cations as fall within the true spirit and scope of this
base sweeps are synchronized with movement of the tap
invention.
95.
I claim:
Calibrating pulse, has a predetermined D.C. potential
Thus, when the movable arms of switches 12S~15S are
1. ln a bore hole logging system in which a transmitter
in their lower position, the scope 92 produces the cali
bration presentation indicated at 90A; and when such
coil induces eddy currents in ambient formations and
such eddy currents in turn induce voltages in a plurality
3,086,168
10
of receiver coils, the improvement which resides in re
cording quantities representative respectively of different
means including means for »adjusting the effect of each
of said voltages induced in said receiver coils to said
voltages induced in said receiver coils in individual re
composite recording whereby effectively the spacing be
cordings and combining information derived from the
individual recordings.
tween receiver coils is adjusted.
2. In a bore hole logging system wherein a transmitter
coil induces eddy currents in ambient formations and
such eddy currents in turn induce voltages in a plurality
of receiver coils, the improvement which resides in mak
ing individual recordings each corresponding to a record
ing of the voltage induced in the corresponding receiver
coil, reproducing the individual recordings to derive cor
responding voltages, combining said voltages to produce a
combined voltage and recording said combined voltage.
l0. An arrangement as set forth in claim 9 in which the
last mentioned means includes means whereby the po
larity of the voltage of a particular one of said receiver
coil voltages is inverted prior to making said composite
recording.
ll. In an induction bore hole logging system wherein
a -tr-ansmitter coil induces eddy currents in ambient for
mations and such eddy currents in turn induce voltages in
a plurality of receiver coils, the steps comprising making
individual recordings of corresponding voltages induced
3. A system as set forth in claim 2 in which a second 15 in said receiver coils, reproducing said recordings to pro
duce signals representative of corresponding receiver coil
transmitter coil induces currents in the ambient forma
voltages and altering said signals to achieve the effect of
tions at a frequency different from the eddy currents pro
different receiver coil spacings, and recording said signals
duced by the iirst mentioned transmitter coil, said second
transmitter coil causing the induction of additional volt
so altered.
12. In an induction bore hole logging system wherein
ages in said receiver coils, the additional steps compris 20
a transmitter coil induces eddy currents in ambient for
ing making individual recordings of each of said addi
mations ‘and such eddy currents in turn induce voltages in
tional voltages induced in corresponding receiver coils,
a plurality of receiver coils which are mounted rigidly in
reproducing said recording to derive other voltages repre
spaced mechanical relationship with each other and with
sentative of said additional voltages, combining said other
voltages with said combined voltage and making a single 25 respect to said transmitter coil, means for producing a
recording of said voltages induced in said receiver coils,
recording in accordance with said combined voltage and
said means including means whereby eifectively the spac
said other voltages.
ing of said receiver coils is altered by adjusting the effect
4. ln a bore hole logging system wherein a transmitter
of said induced voltages to said recording by altering the
coil induces eddy currents in ambient formations and
such eddy currents in turn induce voltages in a plurality 30 polarity of certain »of said induced voltages.
13. In a bore hole logging system wherein a transmit
of receiver coils, the steps comprising making individual
ter coil induces eddy currents in -ambient formations and
recordings of corresponding voltages induced in corre
such eddy currents in .turn induce voltages in a plurality
sponding receiver coils, reproducing the individual re
-of receiver coils, íirst recording means effective to pro
cordings at different reference points to produce corre
sponding reproduced voltages, combining said reproduced 35 duce individual recordings of the voltages induced in cor
voltages to produce a combined voltage, and recording
responding receiver coils on a recording medium, second
recording means comprising a plurality of adjustable re
said combined voltage.
5. The method as set forth in claim 4 involving the ad
producing heads adjustably mounted with respect to cor
responding recordings on said recording medium, said
ditional step of inverting the polarity of one of said repro
duced voltages prior to combining the same with the other 40 second recording means comprising a phase inverting am
plifying means `and variable gain means effective to pro
reproduced voltages so that -said combined voltage in
duce a composite recording on a second recording medium
cludes the effect of said polarity inverted reproduced volt
of a voltage which is the composite of the voltages re
corded on said first recording medium and which are
6. In an induction bore hole logging system wherein a
transmitter coil induces eddy currents in ambient forma 45 subjected to said phase inverting means »and said variable
tions and such eddy currents in turn induce voltages in a
gain means.
14. A method as set forth in claim 4 involving the ad
plurality yof receiver coils, the combination comprising
means for producing a single recording representative of
ditional step of controlling the amplitude of one of said
age.
the combined voltages induced in said receiver coils, said
means comprising means for effectively changing the spac
ing of said receiver coils by predetermined adjustment of
the effect of said induced volt-ages to said recording.
7. In an induction bore hole logging system wherein
a transmitter coil induces «eddy currents in ambient forma
tions and such eddy currents in turn induce voltages in a
plurality of receiver coils, the combination comprising
reproduced voltages prior to combining the same with
the other reproduced voltages so that said combined volt
age includes the eiîect of changing the number of turns of
a corresponding receiver coil.
l5. A system as set forth in claim 12 in which said
producing means includes means whereby effectively
the number of turns of a receiver coil is altered by pre
determined adjustment of the amplitude of said induced
means for producing a recording representative of the
voltages.
16. In a system of the character described wherein
combined voltages induced in said receiver coils, said
individual signals are produced representative of voltages
means including means whereby the polarity of one of
said receiver coil voltages is inverted before being com 60 induced in corresponding receiver coils, the combination
comprising a storage means adapted to store individual
bined with the other receiver coil voltages.
8. An arrangement as set forth in claim 7 including
signals from said coils, read-out means adapted to re
means for adjusting the effect of said receiver coil volt
produce selected ones of said signals from said storage
ages to said recording whereby the effective spacing be
means, individual signal channels having correspond
65 ing ones of said signals from said read-out means applied
tween individual receiver coils is adjusted.
9. ln an induction bore hole logging system wherein
to the inputs thereof, the output of said channels being
a transmitter coil induces eddy currents in ambient for
coupled to common impedance means, visual indicating
mations and such eddy currents in turn induce voltages
means, means scanning said common impedance means
in a plurality of receiver coils, the combinati-on compris
and developing a composite voltage representative of the
ing means for producing individual recordings representa 70 selected signals in selected -ones of said channels, means
tive of each of the voltages induced in corresponding re
applying said composite voltage to said visual indicating
ceiver coils, means for reproducing said individual re
means,
said visual indicating means including time base
cordings to produce the corresponding receiver coil volt
deflection means for sweeping a cathode ray beam in a
ages, means for m-aking a composite recording of said
reproduced receiver coil voltages, the last mentioned 75 ñrst direction while said composite voltage serves Ito
3,086,168
11
simultaneously deflect said cathode ray beam in a sec
ond direction which is perpendicular to said first direc
tion.
17. A system as set forth in claim 16 in which at
leas-t one of said channels includes means whereby the
gain of the signal passing therethrough may be ad
justed and also includes means whereby the polarity
of a signal passing therethrough ymay be inverted.
18. A system as set forth in claim 16 including means
12
recording is used in orientinga composite recording made
in accordance with the voltages induced in said receiver
coils.
.
References Cited in the ñle of this patent
UNITED STATES PATENTS
l2,220,070
2,642,477
2,782,364
controlled by said scanning means for producing a calibra 10
~2,790,158
tion pulse in said visual indicating means.
2,842,735
19. A system as set forth in claim 1 in which the
2,882,988
recordings rof vol-tages induced in 4the individual receiver
2,884,589
coils are produced simultaneously With a depth record«
ing,7 of depth of the coils in a bore hole, and said depth
Aiken _______________ __ Nov. 5, 1940
Puranen etal _________ __ June 16, 1953
`Shuler et al. _________ __ Feb. 19, 1957
Poupon _____________ __ Apr. 23, 1957
«Martin ______________ __ July 8, 1958
Dobrin ______________ __ Apr. 21, 1959
Campbell ___________ __ Apr. 28, 1959
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