High-voltage drilling methods and systems using hybrid drillstring conveyance

Abstract

In at least some embodiments, a high-voltage drilling system includes a power supply to output high-voltage power to an electrical conductor, a bit that extends a borehole based on the high-voltage power, and a hybrid drillstring that transports a fluid flow from the bit to convey detached formation material out of the borehole. At least part of the electrical conductor resides within the hybrid drillstring to convey power to the bit. The hybrid drillstring includes a coiled tubing section and a jointed pipe section.

1 . A high-voltage drilling system that comprises:
 a power supply to output high-voltage power to an electrical conductor;   a bit that extends a borehole based on the high-voltage power; and   a hybrid drillstring that transports a fluid flow from the bit to convey detached formation material out of the borehole, where at least part of the electrical conductor resides within the hybrid drillstring to convey power to the bit,   wherein the hybrid drillstring comprises a coiled tubing section and a jointed pipe section.   
     
     
         2 . The system of  claim 1 , wherein the hybrid drillstring further comprises a connection interface between the coiled tubing section and the jointed pipe section, wherein the connection interface enables fluid flow continuity between the coiled tubing section and the jointed pipe section. 
     
     
         3 . The system of  claim 2 , wherein the connection interface comprises at least one of a double slip connector, a splined quick connector, and a safety valve through which an insulated cable associated with the electrical conductor extends. 
     
     
         4 . The system of  claim 2 , wherein the connection interface comprises at least one electrical interface to connect multiple insulated cables associated with the electrical conductor. 
     
     
         5 . The system of  claim 2 , further comprising a conductor management unit that performs pump down operations to convey the electrical conductor through at least some of the hybrid drillstring. 
     
     
         6 . The system of  claim 2 , further comprising a conductor management unit that performs reel-based operations to extend to convey the electrical conductor through at least some of the hybrid drillstring. 
     
     
         7 . The system of  claim 1 , further comprising a downhole electrical converter that receives the high-voltage power and outputs a converted power for use by the bit. 
     
     
         8 . The system of  claim 1 , wherein the high-voltage power has a voltage level of at least 1000 volts. 
     
     
         9 . The system of  claim 1 , further comprising a bottomhole assembly with the bit coupled to the jointed pipe section, wherein the bit performs pulsed-power drilling operations based on the high-voltage power and wherein the bottomhole assembly does not include a drill collar. 
     
     
         10 . The system of  claim 1 , further comprising a bottomhole assembly with the bit coupled to the jointed pipe section, wherein the bit performs energy-injection drilling operations based on the high-voltage power and wherein the bottomhole assembly includes a drill collar. 
     
     
         11 . A pulsed-power drilling method that comprises:
 connecting a hybrid drillstring to a bottomhole assembly having a bit that detaches formation material based on a high-voltage power;   lowering the drillstring into a borehole;   conveying the high-voltage power to the bit via an electrical conductor, wherein at least part of the electrical conductor resides within the hybrid drillstring; and   flushing fluid to the bit using the hybrid drillstring to convey detached formation material out of the borehole,   wherein the hybrid drillstring comprises a coiled tubing section and a jointed pipe section.   
     
     
         12 . The method of  claim 11 , further comprising connecting the coiled tubing section to the jointed pipe section via a connection interface that enables fluid flow continuity between the coiled tubing section and the jointed pipe section. 
     
     
         13 . The method of  claim 12 , wherein connecting the coiled tubing section to the jointed pipe section via a connection interface employing at least one of a double slip connector, a splined quick connector, and a safety valve through which an insulated cable associated with the electrical conductor extends. 
     
     
         14 . The method of  claim 11 , wherein the high-voltage power has a voltage level of at least 1000 volts. 
     
     
         15 . The method of  claim 11 , further comprising moving the electrical conductor through at least some of the hybrid drillstring using pump down operations. 
     
     
         16 . The method of  claim 11 , further comprising moving the electrical conductor through at least some of the hybrid drill string using reel-based operations. 
     
     
         17 . The method of  claim 12 , further comprising concealing part of the electrical conductor within a surface portion of the coiled tubing section. 
     
     
         18 . A high-voltage drilling system that comprises:
 a bottomhole assembly having a bit that extends a borehole using pulsed-power drilling or energy injection drilling;   a jointed pipe section coupled to the bottomhole assembly;   a coiled tubing section coupled to the jointed pipe section by a connection interface, wherein the jointed pipe section and the coiled tubing section are configured to transport a fluid flow from the bit to convey detached formation material out of the borehole;   an electrical conductor within at least part of the coiled tubing section, the connection interface, and the jointed pipe section;   a rig platform for raising and lowering the bottomhole assembly, the jointed pipe section, and the coiled tubing section; and   a power supply coupled to the electrical conductor to provide high-voltage power via the electrical conductor, wherein a surface portion of the coiled tubing section conceals a surface portion of the electrical conductor between the power supply and the rig platform.   
     
     
         19 . The high-voltage drilling system of  claim 18 , wherein the bit performs energy injection drilling operations based on the high-voltage power having a voltage level of at least 1 k volts, and wherein the bottomhole assembly includes a drill collar. 
     
     
         20 . The high-voltage drilling system of  claim 18 , wherein the bit performs pulsed-power drilling operations based on the high-voltage power having a voltage level of at least 20 k volts, and wherein the bottomhole assembly does not include a drill collar.