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`June 1, 1965
`
`P. W. MARTIN
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`WELL SIGNALING SYSTEM
`
`Filed July 28, 1960
`
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`ATTORNEYS
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`~ LIBERTY EXHIBIT 1027, Page 1
`
`LIBERTY EXHIBIT 1027, Page 1
`
`
`
`
`
`
`
`
`
`

`

`P. W. MARTIN
`
`3,186,222
`
`WELL SIGNALING SYSTEM
`
`Filed July 28, 1960
`
`4 Sheets-Sheet 2
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`LIBERTY EXHIBIT 1027, Page 2
`
`LIBERTY EXHIBIT 1027, Page 2
`
`
`
`
`
`

`

`June 1, 1965
`
`P.W. MARTIN
`WELL SIGNALING SYSTEM
`
`3,186,222
`
`Filed July 28, 1960
`
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`LIBERTY EXHIBIT 1027, Page 3
`
`
`LIBERTY EXHIBIT 1027, Page 3
`
`

`

`June 1, 1965
`
`Filed July 28, 1960
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`WELL SIGNALING SYSTEM
`
`3,186,222
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`
`INVENTOR.
`PHILIP W. MARTIN
`
`BY
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`
`ATTORNEYS
`
`LIBERTY EXHIBIT 1027, Page 4
`
`LIBERTY EXHIBIT 1027, Page 4
`
`
`
`
`
`
`
`

`

`United States Patent Office
`
`3,186,222
`Patented June 1, 1965
`
` 1
`
`3,186,222
`WELL SIGNALING SYSTEM
`_.
`Philip W. Martin, Whittier, Calif.
`(% McCullough Tool
`Co.,. 5820 S. Alameda St, Les Angeles 58, Calif.)
`Filed Yuly 28, 1960, Ser. No. 45,857
`12 Claims,
`(Cl. 73—151)
`
`ot
`
`60
`
`65
`
`70
`
`LIBERTY EXHIBIT 1027, Page 5
`
`2
`Still another object of the present invention is to pro-
`vide a novel transmission system for well logging which
`is more economical to operate than any of those employed
`heretofore.
`One important bit of data which is sought to be trans-
`mitted, from the bottom of the well to the top, is the
`weight applied by the drill string on the drill bit. The
`reason is that it has been found that excessive weight on
`the drill bit can cause the drill stem to flex, whereby drill-
`ing will take place at an angle to the vertical. A crooked
`well is'extremely costly to the oil industry, since it pro-
`duces serious wear on both the drilling and producing
`equipment, making it impractical to produce some other-
`wise productive wells, and sometimes causes the total loss
`of a valuable oil well. Often a hole already drilled is sub-
`sequently lost because the hole is so crooked that the
`drill string will not re-enter the hole.
`Althoughit is desirable not to apply excessive weight to
`the drill bit because of the possibility of drilling a crooked
`hole, on the other hand, the drilling of the hole does re-
`quire a sufficient weight to be applied for obtaining the
`maximumefficiency. All the devices which have been
`produced heretofore attempt, not very successfully,
`to
`solve the problem of preventing a crooked hole by meas-
`uring the weight on the drill bit.
`Yet another object of this invention is the provision of
`an arrangement whereby an indication is achieved at the
`bottom of the well, which can be transmitted to the top
`of the well, as to when a drill bit is about to make a
`crooked hole whereby preventive measures may be taken.
`Still another object of this invention is the provision of
`a simple and improved sensing arrangement which indi-
`cates when the drill bit deviates from a straight hole.
`These and other objects of this invention may be
`achieved in a transmission system which transmits pulses
`wherein the time between successively transmitted pulses
`of opposite polarity is a measure of the quantity sought
`to be transmitted. Repeater stations for these pulses are
`provided along the drill string. Further, a sensing ar-
`rangement for determining when a crooked hole is about
`to occur is achieved by placing two sensing devices, such
`as strain gages, crystals, or electromagnetic transducers,
`on opposite sides of the pipe close above the drill bit to
`indicate the lateral stress on the pipe. The electrical
`outputs of these sensing elemenis may be balanced by op-
`posing one against the other, whereby whenever the pipe
`begins to bend as the result of starting to travel in a path
`other than the vertical path there is a difference in com-
`pression which is measured by the sensing elements and
`which provides a resultant signal, indicating that a crooked
`hole is about to be drilled. This enables the drill opera-
`tor to take the necessary steps to avoid the drilling of such
`crooked hole.
`The novel features that are considered characteristic
`of this invention are set forth with particularity in the
`appended claims, The invention itself, both as to its
`organization and method of operation, as well as addi-
`tional objects and advantages thereof, will best be under-
`stood from the following description when read in con-
`nection with the accompanying drawings, in which:
`FIGURE 1 is a drawing illustrating an arrangement
`for transmitting data from the bottom of the well to the
`top in accordance with this invention;
`FIGURE2 is a schematic circuit diagram of a trans-
`mitter in accordance with this invention;
`FIGURE3 is a block diagram of another type of trans-
`mitter in accordance with this invention;
`FIGURE 4 is a circuit. diagram of a repeater station
`in accordance with this invention;
`FIGURE 5 is a block schematic diagram of a receiver
`in accordance with this invention;
`
`This invention relates to a well signaling system and,
`more particularly, to improvements therein.
`The desirability of having available at the surface of
`a well, while it is being drilled, information concerning
`conditions at and in the vicinity of the drill at the bot-
`tom of the well has long been established. A:consider-
`able number of well signaling systems have ‘been devel-
`oped for the purpose of transmitting the information
`measured at the bottom of the well to the surface. The
`transmission of data from the bottom to the top of the
`well has not proved to be an easy task. The rotating metal
`drill string causes the generation of noise signals which
`adds to the problems attendant those of signal transmis-
`sion. A considerable number of expedients have been
`tried. For example, cables have been lowered tothedrill-
`ing string to contact the bit. The extremely rapid flow of
`fluid down the well with high mud pressures caused by
`mud pumps having on the order of hundreds of horse-
`power, cause terrific strain on such a line, cause stretch,
`and consequently slack in the line. The abrasive muds
`wearthe line rapidly, and very high pressure differentials
`along the length of the drill pipe make this process quite
`impractical.
`Another method which has been tried has been to sig-
`nal, by pressure, pulses on the drill string set up by a puls-
`ing device on the bottom. This has proven to be an
`economic failure and to be unreliable because of its ex-
`treme complexity and high noise level on a drilling rig.
`Still another method has been to use a fixed conductor
`and a series of connections at each joint down the well.
`These have also not been successful. The trouble with
`using joints may be appreciated from the fact that in an
`average drilling string of 10,000 feet there are somewhere
`on the order of 250 joints, or connections, that must be
`made up. This means 250 places for shorts or open cir-
`cuits; consequently, this, again, has not proven successful.
`Industry still very much desires a process of logging-while-
`drilling, because the most important time to obtain lith-
`ological information from the drilling well is while that
`formation is uncontaminated and fresh and immediate
`contact is made with the virgin formation, at which time
`one may withdraw the drill pipe and test that formation
`for productivity, or even spot oil in it immediately as it
`is open, to prevent water from reaching the clays in the oil
`sands and blocking all future production. This inability
`of the oil-drilling industry to realize what it is drilling
`through has probably’ cost the oil industry on the order
`of hundreds of millions of dollars a year, and itis entirely
`probable that the drilling rate per rig could double if a
`successful method of logging-while-drilling and deviation-
`determination-while-drilling entered the field. While the
`industry has spent millions of dollars trying to develop
`apparatus for logging-while-drilling and while large num-
`bers of patents have been issued on logging-while-drilling
`overthe last thirty years, not one commercially successful
`logging-while-drilling apparatus has been obtained.
`An object of this invention is to provide a practical and
`operative well-logging system.
`Another object of this invention is to provide a well
`signaling system wherein the effects of noise signals are
`obviated.
`Yet another object of this invention is to provide a well
`signaling system which is simpler than those employed
`heretofore.
`.
`
`20
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`LIBERTY EXHIBIT 1027, Page 5
`
`

`

`3,186,222
`
`or
`
`10
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`40
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`50
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`60
`
`65
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`70
`
`bottom of the well such quantities as the deviation of the
`drill pipe from the vertical, employing a “pipe-deviation
`transducer” 34, to be subsequently described herein, and
`the earth’s self potential, using an “earth’s self-potential
`transducer” 36, a number of arrangements for which are
`described, shown, and claimed in an application for patent
`by this inventor, entitled “Means and Techniques for
`Logging Well Bores,” Serial No. 670,326, filed July 5,
`1957, now Patent No. 3,079,549 and also in Patent No.
`2,568,241. One embodiment of a transmitter, in accord-
`ance with this invention, will include two pairs of input
`terminals, one pair 38A, 38B of which are respectively
`connected to the collector and emitter of a transistor.39,
`ihe-current-conducting ability of which is controlled by
`the signal applied from the pipe-deviation transducer 34.
`The other. pair 40A, 48B of terminals are respectively
`connected to the collector and emitter of a transistor 41,
`the current-conducting ability. of which is controlled by
`signals received from the earth’s self-potential (SP) trans-
`ducer 36,
`Terminals 38A, 469A are connected to a capacitor 42,
`and also to the emitter 46 of a unijunction transistor 48,
`which also has base-1 and base-2 electrodes, respectively
`50, 52. The base-1 electrode 59 is connected through a
`resistor 54 to the capacitor 42. The base-1 electrode is
`connected through a resistor 56 to the control electrode
`68 of a silicon-controlled rectifier 58. The silicon-con-
`trolled rectifier also has a cathode 62 and an anode 64.
`The cathode 62 is connected through a resistor 66 to
`resistor 54 and capacitor 42. A capacitor 68 is connected
`between the control electrode 60 and resistor 54. The
`anode 64 of silicon-controlled rectifier 58 is connected
`through a diode 78 to input terminal 40B and through
`a resistor 72 to a battery 74. Base-2 of the unijunction
`transistor 48 is connected to the battery 74 through a
`resistor 76.
`Base-1 of the unijunction transistor 48 is connected
`through a resistor 78 to the control electrode 82 of a
`second silicon-controlled rectifier 80, which also has a
`cathode electrode 84 and an anode electrode 86. The
`cathode electrode 84 of silicon-controlled rectifier 80 is
`connected through a resistor 88 to the negative terminal
`of battery 74, as are also resistors 54 and 66, and capacitor
`68. The anode electrode 86 is connected through a re-
`sistor $8 to the positive side of battery 74.
`It is also
`connected through a diode $2 to terminal 38B, and
`through a capacitor $4 to anode 64 of silicon-controlled
`rectifier 88.. A capacitor 96 couples control electrode 82
`to the positive side of the battery 74.
`,
`A third silicon-controlled rectifier 100 has a control
`electrode 102 connected to the cathode 62 of the first
`silicon-controlied rectifier 58. The cathode 104 is con-
`nected to the positive terminal of a bias battery 105.
`The anode 106 is connected to one end of a winding
`108A, which is one-half of a center-tapped transformer
`winding 168 having another half 108B, and a center tap
`1ié. The center tap 116 is connected through a resistor
`112to the positive terminal of the battery 74 and through
`a capacitor 114 to the negative terminal of the battery.
`A fourth silicon-controlied rectifier 146 has its control
`electrode 118 connected to the cathode 84 of the second
`silicon-controlled rectifier 86.
`Its cathode 128 is con-
`nected to the positive terminal of the bias battery 105,
`and its anode is connected to the end of winding 198B.
`A capacitor 124 is connected between the anodes 122 and
`&6 of silicon-controlled rectifiers 86 and 116. Similarly,
`capacitor 124’ is connected between anodes 186 and 64
`of silicon-controlled rectifiers 100 and 58.
`The transformer windings 108A, 108B are wound on
`a laminated core 126, which is toroidal in shape and which
`surrounds the drill pipe. These windings are wound on
`the core to pass through the toroidal aperture. Thus,
`the winding 188 comprises the primary of a transformer,
`of which the secondary comprises the pipe drill stting and
`the carth. The winding 108 corresponds to the winding
`
`LIBERTY EXHIBIT 1027, Page
`
`°B
`
`e)
`FIGURE 6 illustrates recordings illustrative cf what
`is obtained with the use of the invention;
`FIGURE 7 is a block diagram illustrating another
`receiver in accordance with this invention;
`FIGURE8 is a section through a drill string showing
`repeater and transmitter component placementtherein;
`FIGURE 9.is a schematic section through the drill
`string attached to the drill bit illustrating transducer dis-
`position.
`In addition, FIGURE 9 illustrates the place-
`ment of sensing elements to detect the deviation of the
`drill string from the vertical
`in accordance with this
`invention;
`.
`FIGURE 10 illustrates another placement for sensing
`elements to detect drill-string deviation from vertical; and
`FIGURES 11 and 12 are schematic drawings showing
`circuit arrangements of the deviation-measuring apparatus
`in accordance with this invention.
`In FIGURE 1 there is a representation of a well 16
`with a string of drill pipe £2 lowered therein in order to
`drill the hole deeper in accordance with the customary
`rotary drilling practice. The usual derrick and mud
`circulation system and other features attendant to these
`types of wells are not shown to preserve clarity in the
`drawing.
`It will be assumed that by some means, either
`by actual contact of the drill with the earth or by a con-
`ducting material, such as drill mud, there is electrical
`contact between the conducting drill pipe 12 and the earth
`itself, In the lower end of the drill string is the drill col-
`lar section 16. This section serves to apply weight to the
`drill bit 7 and to stiffen the lower section of the drill pipe
`so that a straighter hole may be bored. A portion of the
`wall of the drill collar is hollowed out, as will be shown
`in greater detail hereinafter, in order that the well-logging
`apparatus, incuding the deflection-sensing equipment and
`transmitter in accordance with this invention, will be pro-
`tected and maintained at the bottomof the well.
`Tn accordance with this invention, signals from trans-
`ducing apparatus 17, which convert phenomena sought to
`be logged into such signals, are applied to transmitting
`apparatus 18. The transmitting apparatus 18 is connected
`to a transformer winding 20. The transformer winding
`29, which surrounds the drill casing, serves as the primary
`of a transformer whose secondary comprises the conduc-
`tive drill pipe 12, the drill mud, not shown, and the earth.
`The output of the transmitter may be transmitted by elec-
`tromagnetic induction and appears as a flow of current up
`the drill string, which may be detected by a receiving
`transformer winding 22, which has its output connected
`to the repeater apparatus 24. The output of the repeater
`apparatus 24 is applied to an output transformer winding
`26 to be again transmitted up thedrill string, thus adding
`to or reinforcing the signal already going upthedrill pipe.
`While only two are shown, the receiving-transformer wind-
`ing, repeater apparatus, and output-transformer winding
`are periodically provided, as often as is required along the
`drill string, for insuring transmission of clear signals to
`the surface. Thus, the two repeater arrangements shown
`are by way of exemplification, and not to be construed as
`a limitation. For picking up the transmitted signals, a
`receiver 32 is provided which is conductively coupled
`between the drill string and the earth.
`As will be shown hereinafter, this invention, in opera-
`tion,
`transmits powerful pulses of alternate polarity at
`spaced intervals. The duration of these intervals is deter-
`mined by the quantity sought to be transmitted from the
`bottom of the well.
`In view of this mode of operation,
`substantially no power is required except during the trans-
`mission of the pulse. The actual pulse width is made
`short, so that the actual power drain during the pulse-
`transmission interval is a minimum and pulse amplitude
`is a maximum during transmission.
`Reference is now made to FIGURE 2, which shows a
`circuit diagram of a transmitter. in accordance with this
`invention.
`Let it be assumed that itis desired to transmit from the
`
`LIBERTY EXHIBIT 1027, Page 6
`
`

`

`3,186,222
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`20
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`25
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`30
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`40
`
`10
`:
`
`8
`5
`its cathode goes positive,
`rendered conductive,
`first
`20 represented in FIGURE 1. The transducing appara-
`thereby applying an enabling signal to control electrode
`tus 17 in FIGURE 1 corresponds to the transducers 34
`118, whereby silicon-controlled rectifier 116 can dis-
`and 36 in FIGURE 2. The transmitter apparatus 16 in
`charge capacitor 114, and a pulse of opposite polarity to
`FIGURE1is represented by the circuitry in FIGURE 2.
`said onepolarity is applied to said pipe drill string. Each
`For a description of the operation of the circuit shown
`of the silicon-controlled rectifiers 100, 116. becomes non-
`in FIGURE2,letit first be assumed that, wpon the first
`conductive upon discharge of capacitor 114, since this
`application of potential by battery 74 to the circuit, ca-
`drops the voltage across them below the conduction-sus-
`pacitor 96 applies a positive pulse to the control electrode
`taining value.
`In the event both silicon-controlled recti-
`82 of the second silicon-controlled rectifier 80, rendering
`fiers 100, 116 are turned oninitially, capacitor 124 assists
`it conductive and dropping the potential of its anode 86.
`in reducing the potential at anode 122, in the manner de-
`Capacitor 68 simultaneously applies a negative pulse to
`scribed for capacitor 94;
`to turn off silicon-controlled
`the control electrode 60 of the first silicon-controlled
`rectifier 89. Bias battery 105 assists in turning off silicon-
`rectifier 58, holding it nonconductive. When the second
`controlled rectifiers 100 and 116.
`silicon-controlled rectifier 80 is rendered conductive, ca-
`The silicon-controlled rectifiers 160 and 146 are alter-
`pacitor 42 commences to charge up from the battery 74
`nately enabled to discharge capacitor 114 through the
`controlled by the transducer 36 over a path which in-
`transformer windings. 108A, 108B at intervals determined
`cludes resistor 72, diode 70, terminal 40B, the transistor
`by the amplitude of the signals derived from transducers
`41, terminal 40A, to capacitor 42.. Since the amount of
`36, 34, whereby pulse signals of opposite polarity are
`charging current allowed to flow through transistor 41 is
`transmitted with the information desired being repre-
`determined by the amplitude of the earth’s self-potential
`sented by the interval between these pulses. Although
`transducer signal, the time required to elapse before uni-
`transmission can be performed using unipolar pulses, this
`junction transistor 48 will conduct. depends upon the
`is to be considered within the scope of this invention; the
`signal potential received from the transducer 36.
`reason successive pulses of opposite polarity are used is
`When capacitor 42 reaches a potential sufficiently high
`because it is desired to transmit successive pulses at high-
`to enable unijunction transistor 48 to conduct, the ca-
`powerlevels. The transformer cores would soon saturate
`pacitor 42 is discharged over a path through the emitter
`with unidirectional pulses unless a very, very large amount
`46, base-1 50, and resistor 54. As a result, a positive
`of iron in the core were used. When successive pulses of
`pulse is applied to the control electrodes 60, 82 through
`opposite polarity are used,
`then the full extent of the
`the respective resistors 56,-78. However, since silicon-
`core hysteresis characteristics is used, and. much less iron
`controlled rectifier 86 is already conducting, silicon-con-
`in the core is necessary for transmitting power. Using
`trolled rectifier $8 can and does respond by becoming con-
`pulse spacing to carry intelligence eliminates the effects
`ductive. Capacitor 94 discharges through silicon-con-
`of noise and amplitude modulation.
`trolled. rectifier 58 which reduces the potential at anode
`Thus far there has been described an embodiment of
`86, which cuts off silicon-controlled rectifier 80.
`the invention for transmitting signals from two trans-
`When capacitor 52 has discharged below the potential
`ducers at the bottom of a well to the surface. Those
`required to maintain unijunction transistor 48 conductive,
`skilled in the art, with the teachings provided herein,
`it again begins to charge up, this time over a path in-
`will be able to transmit one or more than two signals
`cluding resistor 90, diode 92, terminal 38B, transistor 39,
`from the bottom of a well, without departing from the,
`and terminal 38A.
`‘This time the interval required for
`spirit and scope of this invention. For example, FIG-
`capacitor 42 to charge up to a potential required to
`UR3 illustrates a block schematic diagram of an ar-.
`render unijunction transistor 48 conductive again depends
`rangement fer transmitting more than two signals from
`upon the signal voltage of the pipe deviation transducer.
`the bottom of a well..This includes a typical pulse-posi-
`When. the unijunction transistor 48 conducts again,
`it
`tion-modulater arrangement, also known as “PPM,”
`operates to switch conduction between the silicon-con-
`which drives a flip-flop circuit or bistable-state circuit 130,
`trolled rectifiers again. Thus, the intervals of conduction
`which drives an opposite polarity pulse transmitter 132.
`of the first and second silicon-controlled rectifiers is de-
`This latter circuit will be recognized as that portion of
`termined by the amplitudes of the signals being produced
`FIGURE 2 which includes the silicon-controlled recti-
`by the transducers. Effectively, the operation of the cir-
`fiers 100, 116,
`the transformer winding 108, and the
`cuit described thus far is that of a bistable-state flip-flop
`capacitor 114.
`circuit which is driven from oneto the other ofits stable
`it
`that
`Assume, for the purpose of exemplification,
`states at a rate determined by the amplitude of two sepa-
`is desired to transmit from the bottom of a well, while
`rate signals derived from two separate transducers. The
`it is being drilled, information from an earth’s self-poten-
`remainder of the circuit in FIGURE 2 emits a positive
`tial transducer 134, a pipe-deviation transducer 136, an
`and then negative pulse into the pipe drill string each time
`earth’s resistivity transducer 138, and an earth’s radio-
`a transfer of conduction between the two silicon-con-
`activity transducer 146. An oscillator 142 drives a saw-
`trolled rectifiers 58, 8@ occurs.
`It is also within the scope
`tooth generator 144. The output of the saftooth gener-
`of this invention for certain purposes to replace trans-
`ator drives a counter 146 and is also applied to a voltage
`ducers 34 and 36, respectively, with variable resistances
`comparator 148, The counter outputs, consisting of the
`and to eliminate transistors 39 and 41. The variable re-
`sampling frequency, are applied to channel-input circuits
`sistances are respectively connected between terminals
`159 and chanel-collector circuits 152 which comprise gate
`38A, 38B and 460A, 49B.. The resistance of these variable
`circuitry, which gates are successively enabled,
`in re-
`resistances is then varied in accordance with the quantity
`sponse to the output of the counter, to successively sample
`being measured, thus varying the timing of the unijunction
`the outputs of cach of the transducers 134-146 and to
`transistors. For example, a pressure transducer can di-
`serialize these outputs. These outputs are applied to the
`rectly vary the timing of these transistors, thus eliminating
`voltage comparator 148.
`transistors 39 and 41.
`The input to the voltage comparator 148 will comprise
`A capacitor 114 is charged up from battery 74 through
`a train of pulses having amplitudes. representative of the
`resistor 112. When silicon-controlled rectifier 58 is
`different
`transducer-output signals, The voltage com-
`rendered conductive,
`its cathode 62 goes positive, thus
`parator 148 converts these amplitude-modulated pulses
`applying an enabling pulse to the control electrode 162 of
`into pulse-width modulated pulses.. The pulse-width mod-
`silicon-controlled rectifier'10@, which is connected thereto.
`ulated pulses are applied to differentiator and clipper cir-
`This enables capacitor 114 to discharge over a path in-
`cuits 154, wherein these are differentiated and clipped
`cluding winding 198A andsilicon-controlled rectifier 100.
`and thus converted to pulse-position modulation pulses.
`Thus, a pulse of onc polarity is applied to the pipe drill
`These are then applied to a mixer 156,
`string. Similarly, when silicon-controlled rectifier 8@ is
`
`50
`
`55
`
`60
`
`65
`
`70
`
`75
`
`LIBERTY EXHIBIT 1027, Page 7
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`LIBERTY EXHIBIT 1027, Page 7
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`

`

`3
`
`18
`
`20
`
`40
`
`8
`t
`It will be appreciated that no standby
`that received.
`The last count of the counter 146 is applied to a triple
`poweris required by the repeater station.
`It operates only
`pulse generator 158, which generates three clasely spaced
`when called upon and in response to pulses of opposite
`pulses in response thereto. These are inserted in the
`polarity. As many of these repeater stations as are re-
`pulse-position pulse train by the mixer 156. The output
`quired may be employed. They insure that the pulses
`of the mixer is applied to the flip-fiop circuit 130, to drive
`it from one to the other stable state in response to each
`spaced by the meaningful intervals are of a sufficiently
`high level that they are not masked or disterted by noise.
`successive pulse. Each of the flip-flop circuit bistable ont-
`The amplitude of these pulses and to a large extent their
`puts is applied to the opposite-polarity pulse generator 132
`shape are not significant. What
`is significant
`is that
`to alternatelytrigger it to generate opposite-polarity pulses,
`pulses occur which exceed the noise levels and which
`which may be in the manner described wherein silicon-
`demark data intervals,
`controlled rectifiers 189 and 116 were alternately triggered
`FIGURE 5 is a block schematic of a receiver (32 in
`for this purpose. Thus, the output of the opposite-polarity
`FIGURES 1) in accordance with this invention for receiv-
`pulse transmitter 132, which is transmitted up the pine
`ing information from the transmitter shown in FIGURE
`drill string, will consist of a train of seven pulses of alter-
`2. The data represented by the interval between two
`nate polarity which is repeated. The spacing between the
`transmitted pulses may be identified by the polarity of
`last three pulses of a train is closer than that of the re-
`either of these pulses. Although pulse polarities alter-
`maining pulses and is always constant. The spacing
`nate, there is a fixed association between the polarity of
`between the last of these three pulses and the first of the
`a pulse generated by the transmitter and a transducer sig-
`succeeding four pulses, as well as the spacing between
`nal, Thus, by way ofillustration, the carth’s self-potential
`the remaining three of these succeeding four pulses, rep-
`data is represented by the interval between a positive and
`resents the amplitudes of the respective signals derived
`from the four transducers 134-148.
`a negative pulse, and the pipe-deviation data is represented
`by the interval between the negative pulse terminating the
`The portion of the block diagram bearing reference
`self-potential data interval and a succeeding positive pulse.
`numerals 142 through 156 is illustrative of an encoder of
`This association is maintained by the repeater stations.
`PPMsignals, which are well-known in the communica-
`The receiver shown in FIGURE5includes a flip-flop
`tion art. For example, see pages 98-101 in a text en-
`or bistable-state circuit 200 which is connected to be
`titled “Telemetering Systems,” by Borden and Mayo-Wells,
`driven from one to the other of its stable states by the
`published in 1959 by the Reinhold Publishing Corp. The
`alternative positive and negative polarity pulses. The in-
`flip-flop circuit 130 is of a type well known in the art.
`The transmitter 132 has been described in connection
`put to the flip-flop circuit is derived by way of suitable
`with FIGURE 2.
`amplifying and filtering equipment either from a pickup
`FIGURE4 is a circuit diagram of the repeater appa-
`transformer winding, such as 36 in FIGURE 1, or froma
`ratus 24 and the receiving-transformer winding 22 and
`connection between the pipe casing and ground. One
`output of the flip-flop circuit is connected to energize two
`transmitting-transformer winding 26. The receiving-trans-
`relay coils 202, 204, Relay coil 282 is part of a fast-
`former winding is center tapped, thus having two halves,
`respectively 22A, 22B.
`The transmitting-transformer
`acting relay having double-pole, double-throw contacts,
`respectively contacts 202A, 282B with swinger 202E, and
`winding is also center tapped, having two halves 26A,
`contacts 202C, 282D with swinger 202F. Relay coil 204
`268. These transformer windings are of the same gen-
`eral
`type as those described for the transmitter, being
`js part of a slower-acting relay having double-pole, double-
`toroidal in form and placed around the pipe drill string
`throw contacts, respectively contacts 264A, 204B, swinger
`204E, and contacts 284C, 264D with swinger 204F.
`to which they are inductively coupled. One end of the
`winding 22A is connected to the control electrode 162
`As flip-flop 260 is operated from one to the otherof its
`of a first silicon-controlled rectifier 169. The opposite
`stable states by the alternate polarity input pulses, it will
`end of the transformer winding 22B is connected to the
`alternately energize and de-energize the relay coils 202,
`control electrode 172 of a second silicon-controlled rec-
`294. Of course,
`the intervals between such energiza-
`tifier 178. The center tap of the winding 22 is connected
`tion and de-energization are directly determined by the
`to cathodes 164, 174 of the silicon-controlled rectifiers,
`intervals between the pulses driving flip-flop 209. Relay
`respectively 160, 170. The opposite ends of the center-
`cecil 262 operates its contacts from the normaly open to
`tap windings 26A, 26B are respectively connected to the
`the normally closed state at a sufficiently higher rate than
`anodes 176, 166 of the silicon-controlled rectifiers 178,
`does relay coil 204 to effectuate a normally open state
`160, The center. tap of the winding 26 is connected to
`while relay 204 is still operated and a closed or operated
`a capacitor 180, the other end of which is connected to
`state while relay 204is still in its normally open state and
`the cathodes 164, 174 of the silicon-controlled rectifiers.
`before it can begin to operate. Alternative to using two
`Across the capacitor 188 there is connected a battery
`relays 262, 294, a single magnetic latching relay of