High voltage explosive assembly for downhole detonations
View Patent ↗A downhole explosive detonation comprises a high voltage electro-explosive initiator comprising an input high voltage power supply with a low impedance shunting fuse, a flexible electrical link and a capacitor discharge unit. Explosive is initiated in a direction approximately parallel, or in another version perpendicular to the capacitor discharge unit. A unique configuration and construction of the assembly allows installation through a small service port in the gun housing structure for more efficient gun arming. A real time downhole voltage monitoring is described that transmits voltage readings to the surface during a firing sequence.
1. A downhole explosive tool firing assembly comprising two rigid support structures connected by a flexible link comprising:
a first support structure for first circuitry that increases an input voltage;
a second support structure for an electrically active second circuitry charged by said increased voltage, said second circuitry including a capacitor, switch and an electro-explosive initiator, a barrel for an electro-explosive initiator driven flyer and a secondary explosive, wherein the switch is adapted to cause electrical power to flow from the capacitor to the electro-explosive initiator, and where the electro-explosive initiator is adapted to detonate an explosive; and,
a flexible, electrically conductive link between said first and second circuitry.
2. A downhole explosive tool firing assembly as described by claim 1 wherein said electro-explosive initiator is of the class comprising a semiconductor bridge (SCB), an exploding bridge wire (EBW) and an exploding foil initiator (EFI).
3. A downhole explosive tool firing assembly as described by claim 1 wherein said first circuitry that increases the input voltage is a flyback transformer followed by a diode rectifier.
4. A downhole explosive tool firing assembly as described by claim 1 wherein said flexible link comprises an electrically conductive, high voltage flexible ribbon cable.
5. A downhole explosive tool firing assembly as described by claim 1 further comprising a surface positioned computer and surface positioned controller operatively connected to said tool firing assembly by a cable extending into a wellbore; a control unit adapted for downlink communication with said surface positioned computer and said surface positioned controller over said cable, wherein the controller comprises a receiver and microprocessor that recognizes a low-voltage activation signal and allows power to said first circuitry.
6. A downhole explosive tool firing assembly as described by claim 1 wherein said first circuitry that increases the input voltage is a charge pump.
7. A downhole explosive tool firing assembly as described by claim 1 wherein said flexible link comprises two or more electrically conductive wires.
8. A downhole explosive tool firing assembly as described by claim 1 wherein said second support structure contains a housing that encompasses said second circuitry, barrel and secondary explosive whereby said housing positions said barrel and secondary explosive at an angle subtending between substantially parallel and substantially perpendicular to the remainder of said second circuitry, which, when activated, causes detonation of an explosive train containing detonating cord.