Apparatuses and methods for supplying electrical power to an electrocrushing drill

Abstract

Methods and apparatuses for directly charging capacitors in a down-hole pulsed power system used for electrocrushing drilling. An above ground power supply is directly connected to the capacitors. The power supply can be a switching power supply, a DC supply, or an AC supply. Capacitor voltage is monitored and controlled. The system reduces noise caused by coupling control signal cables and the power cable, and does not have the ground swing control problems of other charging schemes. The power may alternatively be provided by microwave transmission.

What is claimed is: 
     
         1 . An apparatus for providing power to a down-hole pulsed power system, said apparatus comprising:
 an above-ground power supply;   a down-hole pulsed power system; and   a cable directly connected to said above-ground power supply and said down-hole pulsed power system.   
     
     
         2 . The apparatus of  claim 1  wherein said cable is between approximately 500 feet and approximately 30,000 feet in length. 
     
     
         3 . The apparatus of  claim 1  wherein said down-hole pulsed power system comprises one or more capacitors which are directly charged from said power supply. 
     
     
         4 . The apparatus of  claim 3  wherein said power supply comprises a switching power supply. 
     
     
         5 . The apparatus of  claim 4  wherein said switching power supply utilizes controlled high-frequency current pulses to progressively increase a voltage of the one or more capacitors. 
     
     
         6 . The apparatus of  claim 5 , said switching power supply measuring the voltage and adjusting the current to achieve a desired end state voltage on said capacitors. 
     
     
         7 . The apparatus of  claim 3  wherein said power supply comprises a DC power supply. 
     
     
         8 . The apparatus of  claim 7  further comprising a separate second cable for monitoring the capacitor voltage to control the end state voltage. 
     
     
         9 . The apparatus of  claim 8  further comprising a high voltage probe for monitoring the capacitor voltage, said probe located in the down-hole and transmitting control signals to the surface via said separate second cable. 
     
     
         10 . The apparatus of  claim 3  wherein said power supply comprises an AC power supply. 
     
     
         11 . The apparatus of  claim 10  further comprising a rectifier in said down-hole pulsed power system and a separate second cable for monitoring voltage and/or transmitting voltage monitoring data at a different frequency along said second cable. 
     
     
         12 . The apparatus of  claim 3  further comprising above-ground voltage control circuitry for receiving voltage data from said capacitors and controlling a current output and/or voltage output from said power supply. 
     
     
         13 . A method for providing power to a down-hole pulsed power system, the method comprising directly charging one or more capacitors in a down-hole pulsed power system from an above-ground power supply. 
     
     
         14 . The method of  claim 13  further comprising connecting a cable between the above-ground power supply and the down-hole pulsed power system. 
     
     
         15 . The method of  claim 14  wherein the power supply comprises a switching power supply and the method further comprises utilizing controlled high-frequency current pulses to progressively increase a voltage of the one or more capacitors. 
     
     
         16 . The method of  claim 15 , further comprising measuring the voltage and adjusting the current to achieve a desired end state voltage on the capacitors. 
     
     
         17 . The method of  claim 13  wherein the power supply comprises a DC power supply and the method further comprises monitoring the capacitor voltage to control the end state voltage. 
     
     
         18 . The method of  claim 17  further comprising transmitting control signals to the surface via a signal cable. 
     
     
         19 . The method of  claim 17  further comprising transmitting control signals to the surface on the power cable as an AC signal superimposed on the DC power current. 
     
     
         20 . The method of  claim 19  comprising inductively coupling the control signals into the power cable down-hole and inductively extracting the control signals from the power cable at the surface. 
     
     
         21 . The method of  claim 13  wherein the power supply comprises an AC power supply and the method comprises rectifying the AC power down-hole and monitoring voltage and/or transmitting voltage monitoring data at a different frequency along a signal cable. 
     
     
         22 . The method of  claim 13  further comprising receiving voltage data from the capacitors and controlling a current output and/or voltage output from the power supply. 
     
     
         23 . A method for providing power to a down-hole pulsed power system, the method comprising:
 transmitting microwaves from an above-ground microwave transmitter to a down-hole microwave receiver; and   charging one or more capacitors in a down-hole pulsed power system.   
     
     
         24 . The method of  claim 23  further comprising providing a microwave bandwidth sufficient for transmitting both data and bower to the down-hole pulsed power system. 
     
     
         25 . The method of  claim 23  further comprising transmitting data back to the surface using a down-hole low power transmitter. 
     
     
         26 . The method of  claim 23  further comprising using a metallic drill pipe used to provide drilling fluid as a microwave waveguide, thereby minimizing losses and improving power transmission. 
     
     
         27 . The method of  claim 23  further comprising using a drilling fluid comprising a property selected from the group consisting of non-conductive, non-aqueous, insulating, and dielectric.