Methods and system for controlling downhole pulse power operation are disclosed. A method may include detecting a pulse signal discharged between pulse power drilling (PPD) electrodes and determining an arc characteristic of the pulse signal. The method may further include adjusting pulse power applied to the PPD electrodes based, at least in part, on the determined arc characteristic of the pulse signal.

Methods and system for controlling downhole pulse power operation are disclosed. A method may include detecting a pulse signal discharged between pulse power drilling (PPD) electrodes and determining an arc characteristic of the pulse signal. The method may further include adjusting pulse power applied to the PPD electrodes based, at least in part, on the determined arc characteristic of the pulse signal.

A method for drilling a geothermal well in a subterranean zone includes drilling, with a drill string, a wellbore of the geothermal well in the subterranean zone. An inherent temperature of the rock adjacent a rock face at a downhole end of the wellbore is at least 250° C. While drilling, a drilling fluid is flowed at a temperature at the rock face such that a difference between the inherent temperature of the rock adjacent the rock face and the temperature of the drilling fluid at the rock face is at least 100° C.

An apparatus includes a tube including an inner surface, an inner diameter, and a length. The apparatus also includes a coil spring. The coil spring includes an outer surface, an outer diameter, and a plurality of coil elements arranged along a length of the coil spring. The coil spring can be positioned within the tube and the outer diameter of the coil spring can be less than the inner diameter of the tube. The coil spring can form a waveguide. Related methods of manufacture and systems are also described herein.

An apparatus includes a tube including an inner surface, an inner diameter, and a length. The apparatus also includes a coil spring. The coil spring includes an outer surface, an outer diameter, and a plurality of coil elements arranged along a length of the coil spring. The coil spring can be positioned within the tube and the outer diameter of the coil spring can be less than the inner diameter of the tube. The coil spring can form a waveguide. Related methods of manufacture and systems are also described herein.

A first characteristic of a first discharge of electrodes of a pulse power drilling assembly in a borehole of a subterranean formation is determined. The first characteristic is based on a measurement of the first discharge. A second characteristic of a second discharge of the electrodes is determined. The second discharge occurs after the first discharge, and the second characteristic is based on a measurement of the second discharge. A difference between the first characteristic and the second characteristic is determined. A boundary layer of the subterranean formation is determined based on the difference.

A first characteristic of a first discharge of electrodes of a pulse power drilling assembly in a borehole of a subterranean formation is determined. The first characteristic is based on a measurement of the first discharge. A second characteristic of a second discharge of the electrodes is determined. The second discharge occurs after the first discharge, and the second characteristic is based on a measurement of the second discharge. A difference between the first characteristic and the second characteristic is determined. A boundary layer of the subterranean formation is determined based on the difference.

A drill bit for downhole pulsed-power drilling is disclosed. A pulse-power drill bit may include a bit body; an electrode coupled to a power source and the bit body; a ground ring coupled to the bit body, the electrode and the ground ring positioned such that an electric field produced by a voltage applied between the ground ring and the electrode is enhanced at a portion of the ground ring proximate to the ground ring; a reinforcement material forming portions of the ground ring; a binder material infiltrated through the reinforcement material to form a composite material and forming a first portion of the ground ring; and an machinable material forming a second portion of the ground ring, wherein the composite material has a first resistance to abrasion greater than a second resistance to abrasion of the machinable material.

A drill bit for downhole pulsed-power drilling is disclosed. A pulse-power drill bit may include a bit body; an electrode coupled to a power source and the bit body; a ground ring coupled to the bit body, the electrode and the ground ring positioned such that an electric field produced by a voltage applied between the ground ring and the electrode is enhanced at a portion of the ground ring proximate to the ground ring; a reinforcement material forming portions of the ground ring; a binder material infiltrated through the reinforcement material to form a composite material and forming a first portion of the ground ring; and an machinable material forming a second portion of the ground ring, wherein the composite material has a first resistance to abrasion greater than a second resistance to abrasion of the machinable material.

The systems and techniques described herein may allow for optimized boring through a variety of geologies. A plurality of different boring techniques may be utilized for boring through a geological formation, in order to suit the characteristics of various portions of the geological formation. The systems and techniques described herein includes determining geological features and adjusting operation of boring based on the geological features. In certain such embodiments, boring systems may include a bore head that includes a plurality of boring elements. Such boring elements may be contact and/or non-contact boring elements.