Methods and apparatus for selectively operating multi-charge well bore guns

Well-bore apparatus adapted for operation in a well bore and comprising:

• body means adapted for suspension in a well bore;
• a plurality of electrically-detonatable explosive means on said body means and respectively adapted to be sequentially detonated;
• a suspension cable including electrical-conductor means and having a lower end connected to said body means and an upper end extending to the surface;
• switching means on said body means and adapted for movement to successive switch positions in response to selected switch-operating signals and including first switch means cooperable for sequentially establishing electrical communication with each of said electrically-detonatable explosive means, voltage-responsive diode means operative for conducting electrical current only in response to DC voltage of at least a predetermined potential level, and second switch means cooperable at least at a selected one of said switch positions for electrically connecting said diode means to said electrical-conductor means adjacent to said lower cable end;
• and
• surface-instrumentation means connected to said electrical-conductor means adjacent to said upper cable end and including electrical-source means operatively arranged whenever said switching means are at said selected switch position for passing a constant alternating current through said electrical-conductor means to produce an AC measurement signal representative of the overall IR drop in said electrical-conductor means and for simultaneously passing a constant direct current at no less than said predetermined potential level through said electrical-conductor means and said diode means to produce a DC measurement signal representative of the summation of the IR drop in said electrical-conductor means and said predetermined potential level, and means operable in response to said AC and DC measurement signals for providing a confirming output indication representative of said predetermined potential level whenever said switching means are in said selected switch position.

Apparatus adapted for controlling and monitoring the operation of a plurality of electrically-detonatable explosive devices suspended in a well bore by an electrical cable and respectively adapted to be sequentially detonated and comprising:

• body means adapted for connection to an electrical cable;
• switching means on said body means selectively movable to individual operating positions in response to successive switch-actuating signals and including first switch means adapted for sequentially establishing electrical communication at different ones of said operating positions with electrically-detonatable explosive devices coupled to said body means, and second switch means having a plurality of individual switch contacts at selected ones of said operating positions which are respectively adapted to be electrically connected to an electrical cable supporting said body means;
• means adapted for establishing a plurality of distinctive DC voltage levels respectively characteristic of each of said selected operating positions of said switching means and including a plurality of voltage-responsive Zener diodes respectively chosen to conduct only in response to DC voltage greater than a predetermined minimum voltage level and which collectively are selectively oriented with respect to polarity and operatively interconnected to one another in a serial array with tap connections therebetween respectively connected to said individual switch contacts for collectively defining said distinctive voltage levels;
• and
• surface-instrumentation means including constant-current electrical-source means adapted for selective connection to the surface end of an electrical cable supporting said body means and cooperatively arranged for simultaneously applying thereto a selected AC voltage and a selected DC voltage for obtaining one measurement signal representative of the AC IR drop in an electrical cable supporting said body means and for obtaining another measurement signal representative of the arithmetical summation of the DC IR drop in an electrical cable supporting said body means and of that one of said distinctive DC voltage levels respectively corresponding to the present selected operating position of said switching means, means operatively arranged for correlating said measurement signals to provide at least one output signal as said switching means are moved to each of said operating positions which is representative of that one of said distinctive DC voltage levels, and indicating means operable in response to said output signal and adapted for providing an indication at each of said operating positions which is representative of the present operating position of said switching means.

Well-bore apparatus comprising:

• body means adapted for movement through in a well bore;
• a suspension cable coupled to said body means and including electrical-conductor means adapted to extend between said body means and the surface;
• a plurality of electrically-detonatable explosive devices mounted at spaced intervals on said body means, with at least a first one of said explosive devices being adapted for detonation independently of at least a second one of said explosive devices;
• switching means on said body means including a plurality of ganged multi-contact switches adapted to be successively advanced in unison to corresponding switch positions in response to selected switch-advancing signals, one of said ganged switches being cooperable at a selected first switch position for establishing independent electrical communication with said first explosive device and cooperable at a selected second switch position for establishing independent electrical communication with said second explosive device, and another one of said ganged switches having individual first and second contacts respectively cooperable at said first and second switch positions for establishing independent electrical communication with said electrical-conductor means adjacent to the sub-surface end of said suspension cable;
• first and second voltage-responsive Zener diodes respectively connected to said first and second contacts, with each of said Zener diodes adapted to conduct in response to DC voltage of a given polarity at a predetermined DC voltage potential and operatively defining distinctive first and second operating voltage levels;
• and
• surface-instrumentation means adapted for selective connection to said electrical-conductor means adjacent to the sub-surface end of said suspension cable including constant-current electrical-source means cooperatively arranged for applying AC voltage to said electrical-conductor means to produce one output signal representative of the AC IR drop therein and for simultaneously applying DC voltage of said given polarity in excess of said predetermined DC voltage potential to said electrical-conductor means to produce another output signal representative of the summation of the DC IR drop therein and of said operating voltage level respectively, and signal-combining means cooperatively arranged and adapted for combining said output signals and providing characteristic first and second signals at the surface respectively representing which of said first and second switch positions said switching means are then in.

Well-bore perforating apparatus comprising:

• body means including a plurality of enclosed charge housings tandemly coupled together;
• a suspension cable coupled to said body means and including means defining two electrical conductors;
• perforating means including an electrically-responsive detonator and at least one shaped-explosive charge cooperatively arranged in each of said charge housings;
• switching means on said body means including a plurality of multi-contact switches adapted to be successively advanced to different operating positions in response to selected switch-advancing signals, one of said switches being cooperable at two or more of its said operating positions respectively for independently connecting each of said explosive detonators to said electrical conductors in a predetermined sequence, and another one of said switches having a plurality of contacts respectively cooperable at preselected ones of said operating positions for establishing electrical communication with said electrical conductors;
• voltage-responsive diode means including a plurality of Zener diodes operatively connected to said contacts of said other switch and respectively adapted for conducting in response to DC voltage of a selected polarity and potential for defining distinctive voltage levels respectively representative of each of said preselected operating positions;
• and
• surface-instrumentation means adapted for selective connection to said electrical conductors including constant-current electrical-source means adapted for simultaneously applying AC and DC voltages to said electrical conductors and cooperative whenever said switching means are advanced to each of said preselected switch switch positions for producing one output signal representative of the AC IR drop in said electrical-conductors and for producing another output signal representative of the summation of the DC IR drop in said electrical conductors and said distinctive voltage level corresponding to that one of said preselected operating positions, and signal-combining means cooperatively arranged and adapted for combining said output signals for producing an output signal which is sufficiently independent of said IR drop in said electrical conductors to be representative of said corresponding distinctive voltage level and thereby designate which of said preselected operating positions said switching means are then in.

Well-bore perforating apparatus comprising:

• body means including a plurality of enclosed charge housings tandemly coupled together to provide upper and lower assemblies of said charge housings;
• a suspension cable coupled to said body means and including means defining two electrical conductors;
• perforating means including an electrically-responsive explosive detonator and at least one shaped-explosive charge cooperatively arranged in each of said charge housings;
• switching means on said body means including first and second multi-contact switch assemblies respectively adapted for selective advancement to different operating positions and each having a contact cooperable at a selected operating position for respectively establishing electrical communication with said electrical conductors, one of said switch assemblies being cooperable at two or more of its said operating positions for sequentially connecting said electrical conductors to each of said detonators in said upper assembly of charge housings and the other of said switch assemblies being cooperable at two or more of its said operating positions for sequentially connecting said electrical conductors to each of said detonators in said lower assembly of charge housings;
• voltage-responsive diode means including first and second Zener diodes respectively connected to said selected contacts of said first and second switch assemblies, each of said Zener diodes being respectively adapted to conduct in response to DC voltage of a selected polarity and potential defining a distinctive operating voltage;
• and
• surface-instrumentation means adapted for selective connection to said electrical conductors including constant-current electrical-source means adapted for simultaneously applying AC and DC voltages to said electrical conductors and cooperative upon advancement of said first switch assembly to its said selected operating position for producing a first set of output signals respectively representative of the AC IR drop in said electrical conductors and of the summation of the DC IR drop in said electrical conductors and of the summation of the DC IR drop in said electrical conductors and said distinctive operating voltage of said first Zener diode and cooperative whenever said second switch assembly is advanced to its said selected operating position for producing a second set of output signals respectively representative of the AC IR drop in said electrical conductors and of the summation of the DC IR drop in said electrical conductors and said distinctive operating voltage of said second Zener diode, and signal-correlating means cooperatively arranged and adapted for correlating each set of said output signals to provide a first characteristic indication which is sufficiently independent of said IR drop in said electrical conductors to be representative of said distinctive operating voltage of said first Zener diode and thereby designate whenever said first switch assembly is in its selected operating position as well as for providing a second characteristic indication which is sufficiently independent of said IR drop in said electrical conductors to be representative of said distinctive operating voltage of said second Zener diode and thereby designate whenever said second switch assembly is in its said selected operating position.

Apparatus adapted for operation with a well tool carrying at least one explosive device and comprising:

• body means adapted to be cooperatively associated with a well tool carrying one or more explosive devices adapted to be detonated;
• shot-monitoring means including a transducer cooperatively arranged on said body means for producing at least one output signal having a characteristic parameter functionally related to the magnitude of an explosive force imposed thereon in response to the detonation of such explosive devices;
• and
• oscillator means responsive to said transducer output signal and adapted for producing an oscillator output signal having a characteristic parameter which is in turn representative of said characteristic parameter of said transducer output signal, and means responsive to said oscillator output signal and operatively arranged for producing output indications representative of said characteristic parameter of said transducer output signal.

Apparatus adapted for controlling and monitoring the operation of a plurality of electrically-detonatable explosive devices respectively adapted to be separately detonated in a well bore and comprising:

• body means adapted for suspension in a well bore;
• voltage-responsive diode means operative for conducting electrical current in response to DC voltage at one or more predetermined potential levels;
• switching means on said body means movable to successive switch positions in response to selected switch-operating signals and adapted for sequentially establishing electrical communication with electrically-detonatable explosive devices supported by said body means and with said diode means at one or more selected ones of said switch positions;
• shot-monitoring means including a transducer cooperatively arranged on said body means for producing at least one output signal having a characteristic parameter functionally related to the magnitude of an explosive force imposed thereon in response to the detonation of such explosive devices;
• and
• means adapted for connection to said switching means and said shot-monitoring means by way of electrical-conductor means and including electrical-source means operative whenever said switching means are in one of said selected switch positions for passing alternating current through such electrical-conductor means to obtain an AC measurement representative of the IR drop therein and for simultaneously passing direct current at a voltage level no less than said predetermined potential level through such electrical-conductor means and said diode means to obtain a DC measurement representative of the summation of the corresponding one of said predetermined potential levels and the IR drop in such electrical-conductor means, first means responsive to said AC and DC measurements for providing a first confirming output indication representative of the corresponding one of said predetermined potential levels whenever said switching means are in one of said selected switch positions, and second means responsive to said transducer output signal for providing a second confirming output indication representative of said characteristic parameter of said transducer output signal.

Well-bore apparatus adapted for operation in a well bore and comprising:

• body means adapted for suspension in a well bore;
• a plurality of electrically-detonatable explosive devices on said body means and respectively adapted to be sequentially detonated;
• a suspension cable having a lower end connected to said body means and an upper end extending to the surface and including means defining electrical conductors extending between said body means and the surface;
• control means on said body means including voltage-responsive diode means operative for conducting electrical current only in response to DC voltage of one or more predetermined potential levels, and switching means operable in response to selected switch-operating signals for selectively connecting said electrically-detonatable explosive devices and said diode means to said electrical conductors at one or more selected switch positions;
• shot-monitoring means including a transducer cooperatively arranged on said body means and adapted for producing an output signal having a characteristic parameter representative of the magnitude of explosive forces imposed on said body means upon detonation of one of said explosive devices;
• and
• surface-instrumentation means connected to said electrical conductors and including electrical-source means operatively arranged whenever said switching means are successively moved to each of said selected switch positions for passing a constant alternating current through said electrical conductors to produce an AC measurement signal representative of the overall IR drop in said electrical conductors and for simultaneously passing a constant direct current at no less than said predetermined potential level through said electrical conductors and said diode means to produce a DC measurement signal representative of the summation of the IR drop in said electrical conductors and that one of said predetermined potential levels corresponding to that one of said selected switch positions, means operable in response to said AC and DC measurement signals for providing a first confirming output indication representative of that one of said predetermined potential levels to show that said switching means are in that one of said selected switch positions, and means operable in response to said transducer output signal for providing a second confirming output indication representative of said characteristic parameter of said transducer output signal to signify the relative magnitude of the explosive forces imposed on said body means upon detonation of that one of said explosive devices connected to said electrical conductors in that one of said selected switch positions.

A method for monitoring the operation of an electrically-detonatable explosive device which is supported by a suspension cable having means defining at least two electrical conductors and respectively arranged for selective connection to a source of detonating current by movement of switching means to a selected operating position and comprising the steps of:

• operating said switching means for supposedly moving said switching means to said selected operating position and connecting sub-surface portions of said electrical conductors to the input and output terminals of voltage-responsive diode means arranged to conduct electrical current only in response to DC voltage of at least a predetermined potential level;
• connecting surface portions of said electrical conductors to a DC constant-current electrical source and to an AC constant-current electrical source for obtaining a DC measurement representative of the summation of the IR drop in said electrical conductors and said predetermined potential level and for simultaneously obtaining an AC measurement representative of the IR drop in said electrical conductors;
• and
• correlating said AC and DC measurements for obtaining an output indication which is at least sufficiently independent of said IR drop to be representative of said predetermined potential level and thereby confirm that said switching means are in said selected operating position.

A method for monitoring the sequential operation of two or more electrically-detonatable explosive devices which are supported by a suspension cable having means defining at least two electrical conductors and respectively arranged for selective connection to a source of detonating current by successive advancement of multi-position switching means to different operating positions thereof respectively corresponding to different ones of said explosive devices and comprising the steps of:

• advancing said switching means to each of said selected operating positions for successively connecting sub-surface portions of said electrical conductors to the input and output terminals of a selected different ones of two or more voltage-responsive diode means respectively arranged to conduct electrical current only in response to DC voltage of a predetermined potential level;
• at different ones of said selected operating positions, connecting surface portions of said electrical conductors to a DC constant-current electrical source and to an AC constant-current electrical source for obtaining a DC measurement representative of the summation of the IR drop in said electrical conductors and said predetermined potential level of said selected diode means corresponding to that selected operating position and for simultaneously obtaining an AC measurement representative of the IR drop in said electrical conductors;
• and
• correlating said AC and DC measurements for obtaining an output indication which is at least sufficiently independent of said IR drop to be representative of said predetermined potential level and thereby confirm that said switching means are then in said one selected operating position corresponding to said selected diode means.