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.

A horizontal boring rig that may be used for the excavation of horizontal bores in soil or other substrates without the use of tracks or other supporting equipment. The boring rig may include a hydraulic motor or other powered device for turning an auger or other excavation tool. The hydraulic motor may be pivotally mounted to the boring rig and drive the bore string through an intermediate shaft including a universal joint. The degree of freedom provided by the universal joint and motor mounting prevents breakage of the boring string from deflection or kickback. A front guide may be used to prevent excessive deflection of the universal joint. The boring rig may ride on skids that allow the rig to follow a working grade and may incorporate spoil channels for directing excavated material around or away from the skid feet for improved accuracy in following the working grade.

Jet grouting involves injecting grout into geological material to improve its quality; however, use of jet grouting is limited to situations in which the injection systems can be positioned relatively close to the region to be improved. This can be impractical (for example in heavily built up areas, rough terrain or beneath the seabed) or inconvenient (for example where closing a tunnel would be required). The present invention enables deployment equipment 41 to be passed down a bore in order to deploy material and/or equipment through a hole in the lining of a bore 43 into the underlying geology. In this way, underground assets may be repaired from a location external to the asset, allowing repair in situations where it would be impossible or cost-prohibitive to do so with conventional ground treatment techniques.

Embodiments of the present disclosure relate generally to underground horizontal directional drills and, more particularly, to aspects of drill operation, ground anchoring, and operator assistance features. In some embodiments, a drill is provided that includes an anchor assembly and/or a rear stabilizer that may pivot relative to a carriage frame of the drill. In other embodiments, a roller bearing system that permits the carriage to translate along the carriage frame is provided. In still other embodiments, rests to support the drill rod during makeup and breakout are described.

A rotary drill bit for use with a horizontal directional drill string. A coupler at a proximal axial end is configured to attach the rotary drill bit to a drill head at a distal end of the drill string. A cutting portion at a distal axial end is provided with a plurality of vanes with respective cutters that operate to cut a hole in earth when the rotary drill bit is rotated about a central axis. The plurality of vanes project radially outwardly from a surface of the cutting portion such that the surface forms respective troughs circumferentially interspersed with the plurality of vanes. A plurality of engagement features is positioned axially within the cutting portion and radially inward of an outer cutting diameter to facilitate attachment of a product pullback device between the plurality of vanes without removing the rotary drill bit, or any portion thereof, from the drill head.

Method for installing a geothermal system, comprising: arranging a drilling equipment, including a support structure and a terminal module, mounted on the support structure; by means of the drilling equipment, drilling the soil in succession along a substantially vertical first tract, a substantially horizontal second tract and a substantially vertical third tract, the first, second and third tracts forming a substantially U-shaped well, the first tract having a surface inlet, where the drilling is started, the third tract having a surface outlet, where the drilling is finished, the well crossing a geothermal zone; arranging a casing in the well, so that the casing extends between the inlet of the first tract and the outlet of the third tract; arranging a heat utilization system, associated with an axial end of the casing; arranging a hydraulic system configured to cause a heat transfer fluid to circulate in the casing, so that the heat transfer fluid will absorb heat from the geothermal formation and will release it at the heat utilization system.

A housing defines a through passage along its length and is configured to support a group of electrical isolators surrounding the through passage to form an electrically isolating break in a drill string such that each isolator of the group of isolators is subject to no more than a compressive force responsive to extension and retraction of the drill string. The housing defines a housing cavity to receive an electronics package having a signal port and is configured for electrical connection of the signal port across the electrically isolating break. A housing lid can cooperate with a main housing body to define elongated slots for purposes of enhancing the emanation of a locating signal. A housing arrangement can support electrical connections from an electronics package to bridge an electrically isolating gap.

A controllable drilling head for a drill string for ground drilling with a drilling head tip and a locating pin that carries the drilling head tip, the drilling head tip having a bore slanted to the longitudinal axis and the locating pin being angled to the longitudinal axis, wherein the drilling head tip can rotate on the locating pin, the drilling head tip and the locating pin being arranged in a first angular position relative to one another for straight drilling, and the drilling head tip and the locating pin being arranged in a second angular position relative to one another for drilling that deviates from straight drilling.

A rod section of a ground drilling rod configured at its end to form at least one plug connection and having at one end (a) a connecting plug with an outer contour; or (b) a connecting socket with an inner contour, the outer contour or the inner contour being essentially sinusoidal in cross section.

A sonic-powered method is provided for horizontal directional drilling. The method includes positioning a drilling apparatus at one end of a desired path for a generally horizontal bore to be formed, and attaching a drill bit and a drill rod to a drill head. The method also includes advancing the drill bit and the drill rod into and through the ground along the desired path by advancing the drill head to move along the drill mast. A sonic oscillator of the apparatus applies sonic energy in the form of high frequency vibrations to the drill rod and the drill bit to cause the drill bit to penetrate through an underground formation in front of the drill bit along the desired path. The sonic vibrations help efficiently penetrate through different materials in underground formations. The drilling apparatus can also use sonic vibrations to install drill casings to stabilize the bore.