High voltage explosive assembly for downhole detonations
A downhole explosive detonation assembly with a high voltage electro-explosive initiator having an input high voltage power supply with a low impedance shunting fuse, a flexible electrical link and a capacitor discharge unit. The explosive detonation assembly is adapted to detonate detonating cord from the side.
1. A downhole explosive tool firing assembly comprising two rigid support structures connected by a flexible link comprising:
a first support structure for a first circuitry that increases an input voltage;
a second support structure for an electrically active second circuitry charged by said increased input 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
a flexible, electrically conductive link between said first and second circuitry, wherein the electro-explosive initiator comprises an explosive pellet, a stripper washer, and a flyer, the flyer being initially located between the explosive pellet and the stripper washer, and is adapted to detonate a detonating cord by propelling the flyer into the side of the detonating cord.
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 the flyer is a metallic plate.
7. A downhole explosive tool firing assembly as described by claim 6 wherein the flyer is an aluminum plate.
8. A downhole explosive tool firing assembly as described by claim 7 wherein the flyer is an aluminum plate approximately 0.010 inch thick.
9. A downhole explosive tool firing assembly as described by claim 7 wherein the detonating cord is located within approximately 0.4 inch of the flyer.