Systems and Methods for Directional Pulsed-Electric Drilling

Abstract

Pulsed-electric drilling systems can be augmented with a steering mechanism that shifts at least a portion of a bit relative to a borehole centerline. Illustrative mechanisms include ball-and-socket joints, pivot-and-hinge joints, rotary steerable systems, and bent subs. As the bit detaches formation material using electric pulses, the detached material being flushed away by a flow of drilling fluid, the shifting of the bit from the centerline causes the borehole to turn in the direction of the bit.

1 . A steerable pulsed-electric drilling system that comprises:
 a bit that extends a borehole by detaching formation material with pulses of electric current;   a drillstring that defines at least one path for a fluid flow to the bit to flush detached formation material from the borehole; and   a steering mechanism that causes at least a portion of the bit to shift relative to a centerline of the borehole.   
     
     
         2 . The system of  claim 1 , wherein the steering mechanism comprises a ball-and-socket joint. 
     
     
         3 . The system of  claim 1 , wherein the steering mechanism comprises a rotary steerable system. 
     
     
         4 . The system of  claim 1 , wherein the steering mechanism comprises a hinge joint. 
     
     
         5 . The system of  claim 1 , further comprising an orientation unit attached to the drillstring near the bit. 
     
     
         6 . The system of  claim 5 , wherein the orientation unit includes sensors for determining orientation of the unit relative to a geomagnetic field. 
     
     
         7 . The system of  claim 5 , wherein the orientation unit includes accelerometers for determining orientation of the unit relative to gravity. 
     
     
         8 . The system of  claim 5 , wherein the orientation unit includes inertial or gyroscopic sensors for estimating a position of said unit. 
     
     
         9 . The system of  claim 1 , wherein the steering mechanism is electrically powered. 
     
     
         10 . The system of  claim 1 , wherein the steering mechanism is hydraulically powered. 
     
     
         11 . A steerable pulsed-electric drilling method that comprises:
 extending a borehole with a bit that detaches formation material using pulses of electric current;   flushing detached formation material from the borehole with a fluid flow through a drillstring attached to the bit; and   shifting at least a portion of the bit relative to a centerline of the borehole to steer the extending of the borehole.   
     
     
         12 . The method of  claim 11 , wherein said shifting includes flexing a ball-and-socket joint. 
     
     
         13 . The method of  claim 11 , wherein said shifting employs a rotary steerable system. 
     
     
         14 . The method of  claim 11 , wherein said shifting includes flexing a hinge joint. 
     
     
         15 . The method of  claim 11 , wherein said shifting includes determining a present orientation of the bit using an orientation unit attached to the drillstring near the bit. 
     
     
         16 . The method of  claim 15 , wherein the orientation unit includes sensors for determining orientation of the unit relative to a geomagnetic field. 
     
     
         17 . The method of  claim 15 , wherein the orientation unit includes accelerometers for determining orientation of the unit relative to gravity. 
     
     
         18 . The method of  claim 15 , wherein the orientation unit includes inertial or gyroscopic sensors for estimating a position of said unit. 
     
     
         19 . The method of  claim 11 , further comprising altering a firing pattern of pulses from said bit to favor a higher frequency on an inside of a curve.