EP0098779B1 - A single-wire selective perforation system having firing safeguards - Google Patents

A single-wire selective perforation system having firing safeguards Download PDF

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Publication number
EP0098779B1
EP0098779B1 EP83401358A EP83401358A EP0098779B1 EP 0098779 B1 EP0098779 B1 EP 0098779B1 EP 83401358 A EP83401358 A EP 83401358A EP 83401358 A EP83401358 A EP 83401358A EP 0098779 B1 EP0098779 B1 EP 0098779B1
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EP
European Patent Office
Prior art keywords
module
firing
firing line
pulse
time interval
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.)
Expired
Application number
EP83401358A
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German (de)
English (en)
French (fr)
Other versions
EP0098779A2 (en
EP0098779A3 (en
Inventor
Ernesto E. Bordon
Joseph E. Chapman Iii
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Services Petroliers Schlumberger SA
Schlumberger NV
Schlumberger Ltd USA
Original Assignee
Societe de Prospection Electrique Schlumberger SA
Schlumberger NV
Schlumberger Ltd USA
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Publication date
Priority claimed from US06/394,949 external-priority patent/US4527636A/en
Priority claimed from US06/394,948 external-priority patent/US4496010A/en
Application filed by Societe de Prospection Electrique Schlumberger SA, Schlumberger NV, Schlumberger Ltd USA filed Critical Societe de Prospection Electrique Schlumberger SA
Publication of EP0098779A2 publication Critical patent/EP0098779A2/en
Publication of EP0098779A3 publication Critical patent/EP0098779A3/en
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Publication of EP0098779B1 publication Critical patent/EP0098779B1/en
Expired legal-status Critical Current

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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/11—Perforators; Permeators
    • E21B43/116—Gun or shaped-charge perforators
    • E21B43/1185—Ignition systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42D—BLASTING
    • F42D1/00—Blasting methods or apparatus, e.g. loading or tamping
    • F42D1/04—Arrangements for ignition
    • F42D1/045—Arrangements for electric ignition
    • F42D1/05—Electric circuits for blasting
    • F42D1/055—Electric circuits for blasting specially adapted for firing multiple charges with a time delay

Definitions

  • This invention relates to perforating guns used in well completion operations. More particularly, the present invention relates to a single-wire selective gun perforating system capable of selecting and firing in an arbitrary order each gun in a plurality of guns connected in a firing string.
  • Typical prior-art perforating guns generally used in well completion operations consist of a plurality of guns connected vertically to form an assembly orfiring string suitable for lowering into a well borehole.
  • Each gun will contain one or more shaped charges.
  • Each charge will have a detonator or blasting cap connectable to a firing wire for receiving an electrical firing pulse to detonate the charges.
  • each gun selectable for firing rather than having all guns firing at the same time. Firing all guns at the same time produces perforation spacing determined by the spacing of the guns in the string, usually in a closely-spaced arrangement.
  • individual detonation of the charges permits perforations to be made at various selected depths, and in various selected (often widely separated) zones.
  • the string can be repositioned to the next level where another perforation is desired, and another gun fired. This process can continue until the proper perforation spacing is obtained with the desired number of shots.
  • a further benefit is obtained from the single detonation of the guns a verification that each gun fired and that the proper number of perforations was obtained.
  • the selection and firing of a single gun in the string may involve failures which would prevent the proper firing of the modules.
  • a failure could occur in the gun to be selected that would prevent it from firing; a failure could occur causing the firing of a wrong gun which will be eventually detected; or a failure could occur which caused the undetected firing of a wrong gun. Any one of these failures, especially in many of the prior art devices, would defeat the purposes of having selective firing of the guns in the perforation operations.
  • U.S. Patent 4,051,907 discloses one such system comprising a surface control unit for controlling the selection and firing of the guns in a firing string comprised of a subsurface master unit operatively connected to a plurality of identical slave sub units or firing modules that may be armed and fired in an arbitrary order under control of the master unit and an operator.
  • Sequencing through the firing modules for selection of a module to be fired is under control of the surface located control unit.
  • the selection process begins at the uppermost firing module closest to the master unit.
  • Each firing module contains a pulse counter which receives pulses from the surface via the master slave unit when that module has been connected to the firing line power.
  • a predetermined number of pulses (8 pulses) sequences the counter through nine counts. At selected counts, certain operations are effected in the module.
  • a current pulse is placed on the firing line
  • a switch is closed to charge a firing capacitor with the voltage currently on the firing tine
  • a firing pulse whose amplitude is equal to the current voltage on the firing line is applied to a blocking zener diode which is connected to a firing switch (the firing switch is not closed because the voltage on the firing line is not greater than the break over voltage of the zener diode)
  • a pass-through switch is closed to pass the firing line power on down to the next lower module in the string.
  • a single-wire selective perforating system which provides for the automatic sequencing through the firing modules in a sequence, one at a time, under control of the modules themselves until a module to be selected is receiving power from the firing line. At that time the module can be selected and armed for firing. It would also be advantageous to provide a single-wire selective perforating system which includes safeguards for determining if a single module has been connected in the sequence to the firing line and is operating within predicted power limits thereby insuring that one module is being selected for firing and that only that module will be fired by the firing pulse.
  • One aspect of the present invention is directed to in a single-line selective perforating system having a single firing line for electrically connecting a firing control unit to each of a plurality of shot modules, one at a time in a predetermined sequence, where each module is adapted for connecting the connected control unit to a next module, a method of selecting a module for firing characterized by the step of connecting each module one at a time in the predetermined sequence to the firing line under control of module active time intervals internally generated in the modules, where each module generates its active time interval in response to being connected to the firing line with the next module in the sequence automatically connected to the firing line at the end of the active time for the last connected module if that module was not selected for firing during its active time interval.
  • Another aspect of the present invention is directed to a single-wire selective perforating system for selectively detonating the charges in a plurality of firing modules, one at a time, comprising: (a) a control unit operatively connected to the modules by a single firing line which carries both power and control signals between said control unit and the modules; and (b) a plurality of selectable firing modules vertically connected one to another for form an elongated assembly suitable for lowering into a well borehole, the assembly including said control unit, and characterized in that each module, (i) containing at least one charge and where each module is automatically connected one at a time to the firing line in a predetermined sequence to receive power therefrom, and (ii) in response to receipt of power on the firing line, internally generates a module active time interval during which the module and its charge may be selected for firing by said control unit, each module not selected for firing during its active time interval automatically connecting the firing line to the next module in the sequence.
  • a firing string 10 according to the present invention is shown suspended by a cable 12 in well borehole having a well casing 2.
  • the firing string 10 includes a control unit 14 connected to the cable 12 at the uppermost end.
  • Control unit 14 functions to generate the control signals and firing line 3 power needed by the firing modules to select and arm their charges for firing.
  • Connected one to another below the control unit 14 is a plurality of identical firing modules 5 to form an elongated assembly suitable for lowering into the well borehole.
  • Control -unit 14 contains a current detection means 6 for detecting the amount of current in the firing line 3; a control signal generator 7 for generating control signals to the firing modules to select and arm for firing a module to be selected and to generate a firing pulse to detonate the module selected and armed for firing; and, a controllable power supply 8 for generating the voltage and current needed to power the firing modules.
  • Each of the firing modules 5 contains at least one shaped charge 26 (see Figure 2) with an associated detonator 24 to form a shot or gun for blasting a hole through the well casing 2 into the subsurface formations. Also included in each module is a module logic circuit 18 which functions in cooperation with the control unit 14 and the signals on the firing line 3 generally indicated in Figure 1 by the segmented signal leads 16, 22 contained in each of the modules 5. As will be discussed below, the firing line from the control unit 14 to the various modules 5 consists of a series of segmented leads which are electrically connected together in sequence to form a single firing line 3 as the various modules are connected one at a time in a prescribed sequence to the control unit 14.
  • Each module 5, when physically connected to another module in the string 10 makes electrical contact with a portion of the firing line of the module to which it is connected. That is, the portion 16 of the firing line of the module just connected makes electrical contact with portion 22 of the next higher module to which it is connected.
  • each firing module 5 contains a controllable switch means illustrated as switches 20 and 21, which responds to the module logic circuit 18 to either pass the input portion 16 of the firing line 3 coming into the firing module onto the output portion 22 of the firing line 3 which passes the firing line power on down to the next module in the string (switch 20), or connects the input portion 16 of the firing line 3 to the detonator 24 of the shaped charge 26 (switch 21). If switch 21 is closed in a module, that module would be the module selected for firing and the module logic circuit 18 of that selected module would inhibit further sequencing of lower modules in the string 10 by inhibiting switch 20 from being closed to pass the firing line power on through to the next lower module. In those modules sequenced but not selected during their respective active time intervals, the pass-thru switch 20 could also include switching to ground their detonator so that accidental firing cannot occur.
  • switches 20 and 21 which responds to the module logic circuit 18 to either pass the input portion 16 of the firing line 3 coming into the firing module onto the output portion 22 of the firing line 3 which passes
  • Sequencing of the selectable firing modules begins with the uppermost module connected to the control unit 14.
  • the uppermost module receives power from the control unit 14 when power is first applied to the firing line 3. Thereafter, as each firing module completes its selection process and is not selected for firing, the next lower module in the string is then connected to the firing line. This process continues until the lowermost module has executed its selection sequence.
  • each firing module 5 is best described with reference to Figure 2 which illustrates the functional block diagram for a typical firing module.
  • the input portion 16 of the firing line 3 is connected to a constant current power supply 29 for regulating the voltage on the firing line 3 to produce the supply voltage for the circuits of the module.
  • the firing line is also connected to a firing line pulse detector 37.
  • the output from firing line pulse detector 37 is connected to a flip-flop 41.
  • pulse detector 37 and flip-flop 41 comprise a stop pulse detector 34 for generating a stop pulse to terminate the module active time interval if the module is to be selected and armed for firing.
  • the firing line pulse detector 37 responds to voltage pulses on the firing line to detect when the control unit 14 has issued selection and arming pulses on the firing line 3.
  • each module is a counter circuit means 32 which responds to an internal oscillator clock 28 to produce internally to the module a module active time interval during which the selection of the module for firing is possible.
  • the oscillator clock 28 in conjunction with the number of bits in the binary counter 35 included in the counter means 32, determines the length of the module active time interval.
  • a power reset pulse generator 30 is also included in each module 5 for generating a reset pulse upon the initial receipt of power on the firing line 16. The power reset pulse initiates the start of the active time interval by resetting counter 35.
  • the power reset pulse has an additional function of generating a current increase pulse on the firing line 3 back to the control unit 14 to indicate that a next module has been connected to the firing line 3.
  • This current pulse is the identification pulse for the module, and must meet certain requirements.
  • the magnitude of the increase in the firing line 3 current must be within a predetermined range to indicate that the just connected module is operating in acceptable limits and that only one module is responding to the firing line power.
  • the occurrence of the identification pulse must be within a predetermined window measured from the last identification pulse on the firing line.
  • the control means 14 includes (not shown) a means for detecting the amount of current on the firing line. There are several reasons for monitoring this current. First, by counting the number of identification pulses generated on the firing line, the control means 14 can determine which of the modules has just been connected to the firing line. In this manner, the module to be selected can be detected as the modules automatically sequence through their active times. The control means 14 also includes a means for generating both the selection and arming signals as well as the firing pulse which will detonate the module which has been selected and armed for firing.
  • the stop pulse detector 34 is shown comprised of a firing line pulse detector 37 which responds to signals on the input portion 16 of the firing line 3, and a flip-flop 41 that, in turn, responds to the output of the firing line pulse detector 37 and the binary counter 35, to generate two control signals.
  • a STOP CLOCK signal is outputted by flip-flop 41 on line 50 to one input of an AND gate 33. Also inputted to AND gate 33 is the output from oscillator clock 28. AND gate 33, when enabled, outputs the clocking signal to counter 35.
  • the signal STOP CLOCK functions as a disable signal to inhibit further clocking of the counter 35 when the selection pulse is received on the firing line 3.
  • the improved single-wire selective perforating system referred to above has separated the selection and arming functions to improve the feedback safeguards to avoid failures during firing that result in faulty operations.
  • a single pulse is used to select a module and a sequence of three arming pulses is used to arm the module in a predetermined sequence.
  • the first arming pulse causes the module to be armed to produce a current increase in the firing line 3 current. This current increase must be within a predetermined range.
  • a second arming pulse will remove this current increase. If the value of the current increase is acceptable and the increase was cleared by the second arming pulse, then a third pulse is issued to arm the module for firing. The firing pulse to detonate the charge can then be issued with the assurance that one and only one module will be fired.
  • the flip-flop 41 of the stop pulse detector 34 functions as a set-reset type flip-flop where the set signal comes from the firing line pulse detector 37 and the reset signal comes from the counter 35.
  • the reset signal to flip-flop 41 is labeled ENABLE and is at a logic one state when the Q11 output from the 12-bit binary counter 35 is true.
  • the flip-flop can be "set" to a logic one by a pulse on the set input.
  • a pulse detected by the firing line pulse detector 37 will cause flip-flop 41 to change states (logic zero to logic one) only if the signal ENABLE on signal lead 46 from counter 35 is true.
  • the signal ENABLE will not be at a logic one. After a certain number of clock pulses have been counted, ENABLE goes true making the start of the second portion of the module active time interval. It is during this second portion that the module may be selected and armed.
  • Also inputted to the AND gate 33 is another output from the binary counter 35 (Q12) which represents the most significant bit from the 12-bit counter.
  • the signal on the Q12 output, PASS-THROUGH also controls the pass-through switch 20 which functions to connect the input portion 16 of the firing line 3 to the output portion 22. Additionally, the signal PASS-THROUGH disables clock signals from the oscillator clock 28 from reaching the counter 35.
  • the flip-flop 41 enables the AND gate 33 to pass clock pulses from oscillator 28 to the counter 35 irrespective of whether any pulses are detected by the firing line pulse detector 37 during the first portion of the active interval.
  • the lapsing of the first portion of the time interval is indicated when the signal ENABLE on signal lead 46 goes to a logic one thereby permitting any subsequent pulses detected by the firing line pulse detector 37 to set the flip-flop 41 and disable AND gate 33.
  • the Q12 output of counter 35 will eventually go true and produce the signal PASS-THROUGH to inhibit further clocking of the counter 35.
  • the pass-through switch 20 is closed to pass the firing line power on to the next module down the sequence. Closure of the pass-through switch 20 represents the end of the selection process for the module with the module thereafter connected to the firing line power. Further clocking of the counter 25 is inhibited until the module is reset by removal of power on the firing line 3.
  • FIG 3 The timing relationships between the signals of the control unit 14 and the plurality of firing modules during the sequencing of the modules is illustrated in Figure 3.
  • the voltage and current on the firing line are illustrated for a typical selection sequence involving three firing modules with the third module representing the module to be selected.
  • module No. 1 With application of power in the form of voltage and current on the firing line, module No. 1 will begin to internally generate its module active time interval.
  • the active time interval for each module is illustrated in Figure 3 as composed of two portions, a first and second portions T1 and T2, respectively.
  • the first portion T1 represents the time interval from the initial receipt of power in the module to the time when Q11 of binary counter 35 goes true.
  • the second portion of the time interval T2 represents the remaining portion of the active time interval and represents the time that Q11 fropm counter 35 is true.
  • the end of the second portion T2 of each module time interval is indicated when the Q12 output of the binary counter 35 goes true and Q11 goes false (a true state is represented by a logic one and a false state represented by a logic zero).
  • an identification pulse is generated on the firing line 3.
  • the pulse is shown as a current increase in the firing line current.
  • the increase indicates to the control unit 14 that a module has been connected to the firing line. If the amplitude of the current increase on the firing line for the identification pulse does not fall within a predetermined range, the control unit 14 will cease sequencing of the modules because a faulty operation, such as more than one module 5 responding to the application of power on the firing line 3 or that the module just connected is not operating within predetermined limit, is indicated.
  • the signal for the firing line current shown in Figure 3 indicates, there is an increase in the firing line current each time that another module is connected to the firing line apart from the superimposed current increase pulse for the identification pulse.
  • module 1 At the end of the module active time interval for module 1, its pass-thru switch 20 is closed to connect module 2 to the firing line power. As shown in Figure 3, module 2 and module 1 are now connected to the firing line resulting in a net increase in the amount of current on the firing line. This is generally illustrated as a step function increase. Superimposed on this step increase is the identification pulse for module No. 2.
  • control unit 14 monitors the time interval as measured from the receipt of the last identification pulse to receipt of the next identification pulse. Unless each identification pulse falls within a predetermined time window measured from the last pulse on the firing line 3, the control unit 14 will terminate further sequencing of the firing modules because a faulty situation is indicated.
  • An additional function of the identification pulses to the control unit 14 is to function as a clocking pulse to enable the control unit 14 to count which of the modules has just been connected to the firing line 3 power. Thus, when the identification pulse for module 3 is received and the identification pulse conditions are met, control unit 14 will know that the module to be selected, module 3, has just been connected to the firing line 3.
  • any pulses occurring on the firing line during the first portion of the time interval will have no effect on the selection anti arming of a module. Only during the second portion of the active time interval T2 will the flip-flop 41 be enabled to receive setting pulses detected by the firing line pulse detector 37 to select and arm the module.
  • the control unit 14 will generate a selection and arming pulse on the firing line indicated as a voltage pulse on the firing line voltage during T2 for module No. 3.
  • flip-flop 41 will be triggered to terminate further counting of the counter 35 and to generate ARM CONTROL to the firing switch 21. With ARM CONTROL true, firing switch 21 will be closed connecting the detonator 24 in module No. 3 to the firing line through its zener diode 43.
  • the module Since further clocking of counter 35 has been terminated by receipt of the selection pulse and the setting of flip-flop 41, the module will no longer be in an active time interval generation operation, but will have to be in a selected state. Further selection of lower modules is terminated and detonation of module No. 3 can occur at any time control unit 14 wishes to apply a firing pulse on the firing line. Should detonation of the selected and armed module not be desired, the selection sequencing process can be repeated by resetting all of the modules back to the initial state by removing the firing line voltage and current momentarily. When the power is removed, all the pass-through switches 20 and the firing switch 21 in module 3 will be switched to their open position so that only the first module connected to the control unit 14 will receive power on the firing line 3 once power is again returned.
  • a single-wire selective perforating gun system in which a plurality of identical firing modules are connected, one to another, to form an elongated assembly suitable for lowering into a well borehole. Included in the assembly is a control unit for generating power and firing line signals to each of the firing modules as each module is connected one at a time in a sequence to the control unit.
  • Each of the firing modules generates internally an active time interval during which the module can be selected and armed for firing by the control unit.
  • the active time interval begins when power is applied to the module by connection of the module to the firing line.
  • Each firing interval has a first and a second portion.
  • the firing module generates an identification pulse to the control unit to indicate that a next module has been connected to the firing line.
  • the control unit counts the modules as they are connected to the firing line to determine when the module to be selected is generating an active time interval.
  • the control unit may select a module for firing by issuing a selection control pulse onto the firing line. Pulses on the firing line during the first portion of the active time interval are disregarded by the module since a module may only be selected and armed during the second portion of the time interval.
  • each module generates an identification pulse on the firing line which the control unit monitors to determine if the module is operating within acceptable power limits and that the sequencing through the modules has occurred within prescribed time limits. Only when conditions are proper will the control unit select and arm for firing the module to be selected.
  • each firing module 5 is best described with reference to Figure 5 which illustrates the functional block diagram for a typical firing module 5.
  • Figure 5 illustrates the functional block diagram for a typical firing module 5.
  • the input portion 16 of the firing line 3 is shown connected to a regulated power supply 29 which produces the supply voltage for the circuits of the module.
  • a regulated power supply 29 which produces the supply voltage for the circuits of the module.
  • the firing line is also shown connected to a control pulse detector 34.
  • the control pulse detector 34 consists of a R-C network to shift the DC level of the control pulse which is applied directly into the clock input of a 4-bit shift register 38.
  • the shift register's clock input stage acts as a comparator to detect the control pulses.
  • the control pulse detector 34 generates on the Q1 output of shift register 38 the signal STOP CLOCK in response to a selection control signal on the firing line during the active time interval.
  • the selection control signal if received at the proper time during the active time interval, selects the module for firing by terminating the module's active time interval which prohibits switch 20 from thereafter closing and passing power to the modules below the selected module.
  • the control pulse detector 34 detects the sequence of arming control signals from the control unit 14. This sequence of arming control signals is used as a safeguard detection method for determining if one and only one firing module 5 is responding to the arming sequence.
  • the lastthree stages of the 4-bit register 38 comprise an arming circuit which responds to the sequence of arming control signals detected by the control pulse detector 34 to generate a feedback current pulse to the control unit 14.
  • This feedback current pulse on the firing line 3 functions to indicate to the current detection means 6 in the control unit 14 that one and only one firing module is responding to the sequence of arming control signals.
  • this feedback current pulse acts as a safeguard detection method for potential problems which would result in the improper firing of the perforation guns.
  • the arming sequence feedback current pulse on the firing line 3 has a predetermined amplitude of current increase over the firing line steady state current to indicate that only a single firing module is responding.
  • the 4- bit shift register 38 operates to produce this predetermined current pulse in the firing line as follows: As long as the signal on line 46 into shift register 38 (the data (D) input) is at a logic 0, any detected control signals or pulses on the firing lines will sequentially shift logic Os onto the various stages of the shift register 38. Logic Os in the stages of the shift register 38 represent the reset condition. Thus, any pulses detected by pulse detector 34 when the D input to shift register 38 is at a logic 0 will result in no change in the logic state of the shift register, and thus no action by the arming circuit.
  • the first control signal detected by the stop pulse detector 34 on the firing line will shift a logic 1 into the first stage of the register.
  • the output of the first stage, Q1 is the signal STOP CLOCK which is applied to signal line 50.
  • the function of STOP CLOCK is to inhibit an oscillator clock 28 which is the internal time base for the logic circuits 18 from generating further clocking signals. The absence of further clocking pulses terminates the generation of the module's active time interval and further sequencing of any lower modules.
  • This first received control signal represents the selection control signal for selecting a module for firing. In other words, if STOP CLOCK goes to a logic 1, this module will be selected for firing.
  • the conditions under which the D input shift register 38 is at a logic 1 are discussed in more detail below.
  • any further control signals detected by the stop pulse detector 34 when the D input is at a logic 1 will cause a corresponding logic 1 to be shifted into each of the stages of the shift register 38, with the logic 1 shifted for each control signal detected.
  • a resistor R2 Connected between the output of the second stage, Q2, and the third stage, Q3, of the shift register 38 is a resistor R2.
  • a series of arming pulses will then be generated by the control unit 14 to the arming circuit of the selected module 5 to generate the arming status feedback current pulse indicating that a single module is responding.
  • This sequence of arming control signals consists of three pulses on the firing line. The first pulse causes the Q2 output of shift register 38 to go to a logic 1. At this time, the Q3 output of the shift register 38 is at a logic 0 thereby causing the 4-bit register 38 to supply current through R2 in the direction Q2 to Q3. This results in an increase in the amount of current drain on the power supplied by the firing line in an amount determined by the magnitude of R2. If a single firing module is responding, a predetermined current increase results.
  • Arming ofthe module forfiring is accomplished by issuing a third arming control signal on the firing line 3. This results in the fourth stage, Q4, of shift register 38 becoming a logic 1.
  • the Q4 output of shift register 38 is applied to signal line 39 as the signal ARM CONTROL.
  • the signal ARM CONTROL is supplied to the controllable arming switch 21.
  • arming switch 21 and pass-through switch 20 are each solid state switches manufactured by International Rectifier as its model IRSC 232. Closure of switch 21 connects the detonator 24 for the shaped charge 26 to the input portion 16 of the firing line 3 thereby arming the module for firing.
  • a clock oscillator circuit 28 is provided as the module time base for generating clock pulses that will be counted by a 14-bit binary counter 34 to generate the active time interval for the module.
  • the active time interval for each module is divided into two equal portions, T1 and T2 (see Figure 3). During the first portion T1, the module will perform an identification process whereby the module 5 generates a plurality of feedback pulse to the control unit 14. The pulses are processed by the control unit 14 to uniquely identify which module 5 is currently generating an active time interval.
  • the D input to shift register 38 is a logic 0 during the first portion T1 of the active time interval and prevents any selection of the module for firing.
  • the module is "enabled” to be selected, armed and fired by the control unit 14.
  • the D input to shift register 38 is at a logic 1.
  • the D input logic level is controlled by the 14-bit binary counter 35 whose operation is described in more detail below.
  • a uniquely identifying pulse is generated in the control unit 14 to identify which module 5 is currently generating an active time interval.
  • the generation of this uniquely identifying pulse occurs as follows: An identification signal generator comprised of the power-up reset circuit 30 and a 4-bit shift register 33 is provided with each firing module 5 for generating a plurality of feedback current pulses to the control unit 14 during the first portion of a module's active time interval.
  • the power-up reset circuit 30 produces a power reset pulse to clear the logic 18 circuits on receipt of power on the input portion 16 of the firing line.
  • the 4-bit shift register 33 functions in a similar way to the shift register 38. That is, if the data input D is at a logic 1, clock pulses will cause a logic 1 to be shifted through the various stages of the register.
  • the clock source for the shift register 33 is the output of the oscillator clock 28.
  • the data input for shift register 33 comes from a 14-bit binary counter 35 which also responds to the clock 28.
  • the Q6, or the output of the sixth stage of the binary counter 35 is applied as the data D input to the shift register 33.
  • a resistor R3 is connected between the Q1 and the Q3 output of the shift register 33 and operates in a manner similar to R2 to create a current increase in the firing line power when there is a difference in the logic states of Q1 and Q3.
  • resistors R2 and R3, acting in cooperation with the shift registers 38 and 33, respectively, represent a first and a second load connect means for generating current increases on the firing line 3.
  • the Q13 output of the binary counter 35 is also applied to signal line 48 as the control input to the solid state by-pass switch 20 which responds to the logic state of Q13 to connect the input portion 16 of the firing line to the output portion 22 thereby powering up the next lower module in the string.
  • the stopping of oscillator clock signals on the occurrence of a logic 1 on the Q13 output will thereafter keep the pass-through switch 20 closed until the power on the firing line is removed.
  • the active time interval for the module will be determined by the time required to count a predetermined number of clock cycles of the clock 28.
  • the first portion of the module active time interval T1 is measured from the application of the firing line power to the module (the occurrence of the power reset pulse) up to the time that the Q12 output of the binary counter 35 goes to a logic 1.
  • the second portion T2 of the module active time interval is measured by the length of time that Q12 is at a logic 1 (the length of time from when Q12 goes to a logic 1 until when Q13 goes to a logic 1).
  • the output Q13 of the binary counter 35 is applied as a second enable input to the oscillator clock 28 to also inhibit the generation of any clock signals when Q13 is at a logic 1.
  • the disabling of the clock 28 when Q13 is true (logic 1) indicates that the module active time interval for this module has been completed without this module being selected for firing, and until the power on the firing line is removed, this module will be in a by-passed state.
  • the control unit 14 can know precisely if the module currently generating an active time interval is the module to be selected and armed for firing.
  • a faulty module which does not generate downhole an active time interval can be detected from the absence of its uniquely identifying pulse envelope in the sequence of envelopes for the modules when all the modules are sequenced and none is selected for firing.
  • each module generates 64 current pulses on the firing line during T1.
  • the control unit 14 will count the pulses received during T1 of each module's. active time interval to determine the amount of time required by the module to generate the 64 pulses.
  • the time interval thus developed represents the envelope of the feedback identification signal from a particular module. Since the oscillator clock circuits will vary somewhat, each module is likely to produce a pulse envelope that is unique to the module.
  • each firing module oscillator clock 28 can be slightly altered to produce unique envelope pulses for each module, and this envelope can be measured uphole or downhole to uniquely identify each module. In this way, there is no need to count how many modules have been connected to the firing line in the selection sequence.
  • the uniquely identifying pulse determines when a given module is connected to the firing line and generating an active time interval. Isolated noise pulses on the firing line will not generate an error condition because 64 pulses must be received.
  • 64 pulses is the ideal number, it is possible to permit a small band or variation of total pulses received and still result in a unique identification of the module. Thus 64 ⁇ n pulses are permitted and still be able to uniquely identify a given module.
  • the shift register 33 Connected to the reset input of the shift register 33 is the Q12 output of the binary counter 35.
  • the shift register 33 acting in combination with the.Q6 output of the binary counter 35 and the clock 28, produces a predetermined number of short duration current pulses onto the firing line 3 until such time as Q12 goes to a logic 1.
  • the shift register 33 is reset and inhibited from further generating any current pulses on the firing line.
  • the Q12 output of binary counter 35 is also applied as the data D input to the shift register 38 as the signal labeled ENABLE.
  • FIG 4 a timing diagram of various signals within the single-wire perforating system according to the present invention is shown.
  • the third module down from the control unit 14 is the module to be selected.
  • FIG. 4 illustrates the first and second portions of each module active time interval, T1 and T2, respectively.
  • T1 and T2 During the first portion T1 of each module active time interval, 64 current pulses are generated in the current signal on the firing line 3.
  • the time interval required to generate the 64 pulses by each of the modules is different so that the width of the resulting envelope pulse, labeled t1 through t4, are different and each pulse uniquely identifies its associated module.
  • the noise pulses occurring between module No. 1 and module No. 2 results in a narrow pulse envelope for an identification pulse, and because it didn't contain the correct number of current pulses, it will be disregarded by the control unit 14 and reported to the surface for possible action.
  • the control unit 14 will generate the module selection control signal and the sequence of three arming selection control signals during the second portion T2 of the module active time interval. These control signals are applied as voltage pulses on the power voltage of the firing line. The first control signal received during the second portion of module No. 3's active time T2 will select the module for firing and thereby terminate further generation of the module active time. This, in turn, prevents further sequencing of any lower modules.
  • the module With receipt of a selection control pulse during T2 of the module active time for module No. 3, the module will enter into a selected state during which it can be armed for firing if the safeguard feedback detection sequence determines that the modules are operating properly.
  • This safeguard detection sequence begins with receipt of the first arming control signal by the arming circuit.
  • the arming circuit produces the predetermined current pulse increase in the firing line current illustrated in Figure 4 as the arming status pulse.
  • the second arming pulse will be issued by the control unit 14 to remove the arming status current pulse if the proper value for the current increase was detected.
  • the control unit 14 proceeds to issue a third arming control signal to cause the arming switch 21 (see Figure 2) to close connecting the detonator 24 to the firing line 3. With the closure of the arming switch 21, the control unit 14 can then issue a firing pulse on the firing line at any time it desires to fire the module. Rather than detonating the module, however, the control unit 14 can reset the modules to select a different module by simply removing the power on the firing line without generating a firing pulse.
  • This safety feature can be used to sequence through each of the firing modules to determine if all modules are operating properly, and to further define the unique identifying envelope for each pulse as a function of the given operating conditions that the gun is currently experiencing, since temperature variations encountered downhole may cause fluctuations in the time base in each firing module. A time base variation will change the time required to generate the 64 pulses that uniquely identifies the module.
  • control unit 14 can determine if the modules are operating as expected by measuring the amount of current increase as each module is added to the firing line.
  • the increase in the firing line current as each module is added to the firing line is illustrated in Figure 4 at the start of each module active time interval as a step function.
  • redundant safeguard detection methods are provided for determining faulty conditions or failures in the firing system before any attempt to fire the guns is made. These failures may be classified as failures resulting in the firing of a wrong gun which could be noticed or the failures which cause the undetected firing of a wrong gun.
  • the response from every module during the first portion of the module's active time interval is a train of 64 feedback current pulses.
  • the control unit 14 detects these feedback pulses and forms the envelope of the pulse train to uniquely identify the modules as they are connected to the firing line.
  • the 64 pulses generated during the first portion of each module active time interval is recognized as correct if the number of pulses detected in the sequence is within a certain number of the correct number.
  • false pulse trains such as the noise pulses illustrated in Figure 4 will be discarded, and the surface equipment could be informed about their occurrence.
  • the envelope of the feedback pulses during the first portion of the active time interval is a measurable time interval of approximately half the active period of the module.
  • the control unit 14 is built to accept a wide range of active period values and is able to measure them with high resolution. Every module 5 in the gun string 10 can be individualized through a dispersion in their various clock 28 frequencies. Even if the frequencies are not made different, the frequency distribution of the various frequencies represents a random process where the difference between adjacent modules may not always be measurable, but the probability of this condition to leave a failure undetected is sufficiently low. Otherwise, the modules could be trimmed to different values of their active periods and placed sequentially in the string.
  • the present invention is able to sequence through each of the modules without firing any module, it is possible to measure, before the guns are fired, the time intervals for each of the modules. These values can form a reference table of active times versus module position which can be used later to verify the selections during the perforation operations.
  • the control unit 14 includes a high resolution measurement of the current supplied to the firing line. After a module is selected, the current on the firing line is proportional to the number of modules connected to the line, and therefore, indicative of the module selected.
  • the total current drain produced by all the firing modules connected to the firing line may not be precise enough to indicate the number of modules, but the single addition or subtraction of a module on the firing line produces a predictable change in the current.
  • reference values of supply current can be measured with selection cycles of progressive length. In other words, a selection cycle to select module No. 1 followed by a selection cycle for module No. 2, etc., can be run to determine how this increase in firing line current occurs for each module. These measurements can be made simultaneously with the identification pulse measurements.
  • the verification of the active time interval and line current is a safeguard in situations where a failure reduces the active period of a module to zero and the failed module powers up together with the next lower module, and is by-passed without being accounted for.
  • the number of interconnected modules is measured by a selection cycle of unrestricted length.
  • the control unit 14 will count the feedback pulse trains, and therefore the number of modules. As the last module is bypassed, the measurement of the supply current will indicate the condition of the line below the last unfired gun. The same measurement can locate any failure in the wiring between modules.
  • the control unit 14 can detect an open or short circuit in the line and determine up to which gun the string is still operable.
  • the active module should be able to forward the firing current to the blasting cap. But any of the by- passed modules could be defective and remain "active" after being by-passed. The module with the faulty circuitry could fire in parallel with the selected one, and eventually go undetected. As a safeguard against this failure, the selected module is not ready to accept the firing current immediately after the selection control signal is applied to the firing line 3, but requires an arming sequence of several arming control signals.
  • arming is implemented in accordance with the present invention with three additional control pulses on the firing line 3 similar to the one used in the selection process. Only the selected modules should be able to receive these pulses.
  • the first arming pulse will increase by a fixed amount the supply current drain in the active module with the second pulse returning the current to its previous value. If the increase in current was within acceptable limits, a third pulse will finally close the arming switch 21 between the detonator or blasting cap 24 and the firing line 3. Simultaneously, or sometime after the third arming control pulse, the control unit 14 will connect a firing capacitor to the firing line and produce the firing current.
  • a single-wire selective perforating gun system in which a plurality of identical firing modules are connected, one to another, to form an elongated assembly suitable for lowering into a well borehole. Included in the assembly is a control unit for generating power and firing line signals to each of the firing modules as each module is connected, one at a time, in a sequence to the control unit.
  • Each of the firing modules generates internally an active time interval during which the module can be selected and armed for firing by the control unit.
  • the active time interval begins when power is applied to the module by connection of the module to the firing line.
  • Each firing interval has a first and a second portion. During the first portion, a unique identification pulse is generated in the control unit to indicate that a particular module from among the plurality of modules is connected to the firing line and is generating an active time interval. In this way, the control unit is able to determine when a particular module is available for selection.
  • the control unit may select a module for firing by issuing a selection control pulse onto the firing line. Pulses on the firing line during the first portion of the active time interval are disregarded by the module since a module may only be selected and armed during the second portion of the time interval.
  • the control unit will issue a sequence of three arming signals to arm the module.
  • the first and second arming control pulses will produce a current pulse increase on the firing line power of a predetermined amplitude to indicate to the control unit if one and only one module is responding to the arming sequence. If the current increase is within acceptable limits, the control unit will then issue a third arming control signal to connect the detonator of the charge in the module to the firing line.
  • the control unit 14 can issue a firing pulse to detonate the charge or can remove the firing line power to reset all of the modules and permit the selection process to be repeated to select a different module.

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EP83401358A 1982-07-02 1983-07-01 A single-wire selective perforation system having firing safeguards Expired EP0098779B1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US06/394,949 US4527636A (en) 1982-07-02 1982-07-02 Single-wire selective perforation system having firing safeguards
US06/394,948 US4496010A (en) 1982-07-02 1982-07-02 Single-wire selective performation system
US394948 1982-07-02
US394949 2003-03-21

Publications (3)

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EP0098779A2 EP0098779A2 (en) 1984-01-18
EP0098779A3 EP0098779A3 (en) 1985-11-06
EP0098779B1 true EP0098779B1 (en) 1987-09-30

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EP (1) EP0098779B1 (da)
AU (1) AU564471B2 (da)
DE (1) DE3373939D1 (da)
DK (1) DK168168B1 (da)
IN (1) IN162141B (da)
MX (1) MX158750A (da)
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EG19633A (en) * 1983-12-22 1995-08-30 Dynamit Nobel Ag Process for chronologically staggered release of electronic explosive detonating device
SE458721B (sv) * 1984-04-05 1989-04-24 Saab Training Systems Ab Anordning foer uppsoekning och avfyrning av en pyroteknisk laddning
US4860653A (en) * 1985-06-28 1989-08-29 D. J. Moorhouse Detonator actuator
US4869171A (en) * 1985-06-28 1989-09-26 D J Moorhouse And S T Deeley Detonator
AU595916B2 (en) * 1986-08-29 1990-04-12 Ici Australia Operations Proprietary Limited Detonator system
FR2660749B1 (fr) * 1990-04-05 1994-07-08 Lacroix E Tous Artifices Systeme de declenchement sequentiel controle et automatique d'une pluralite de charges utiles pyrotechniques.
US7870825B2 (en) * 2003-07-15 2011-01-18 Special Devices, Incorporated Enhanced method, device, and system for identifying an unknown or unmarked slave device such as in an electronic blasting system
CN109115060B (zh) * 2018-10-15 2023-09-19 中国工程物理研究院电子工程研究所 一种冲击片雷管可调通用型脉冲电流发生装置及其控制方法

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US4051907A (en) * 1976-03-10 1977-10-04 N L Industries, Inc. Selective firing system

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US3010396A (en) * 1957-12-31 1961-11-28 Western Co Of North America Selective firing apparatus
US3495212A (en) * 1968-09-05 1970-02-10 Schlumberger Technology Corp Methods and apparatus for detecting the sudden movement of a tool in a well
US3517757A (en) * 1968-09-23 1970-06-30 Schlumberger Technology Corp Switching apparatus for selectively actuating explosive well-completion devices
DE2945122A1 (de) * 1978-02-01 1980-05-22 Ici Ltd Elektrische verzoegerungsvorrichtung
NZ199616A (en) * 1981-02-12 1985-11-08 Aeci Ltd Sequential activation of detonators:timing mode controllers respond sequentially to signals from shot exploder

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Publication number Priority date Publication date Assignee Title
US4051907A (en) * 1976-03-10 1977-10-04 N L Industries, Inc. Selective firing system

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OA07480A (en) 1984-12-31
IN162141B (da) 1988-04-02
EP0098779A2 (en) 1984-01-18
DK305583D0 (da) 1983-07-01
DE3373939D1 (en) 1987-11-05
NO167995B (no) 1991-09-23
DK305583A (da) 1984-01-03
MX158750A (es) 1989-03-10
EP0098779A3 (en) 1985-11-06
AU1648483A (en) 1984-01-05
NO832177L (no) 1984-01-03
AU564471B2 (en) 1987-08-13
NO167995C (no) 1992-01-02
DK168168B1 (da) 1994-02-21

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