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.

A piston for use in a rotary steerable system includes a body formed from a first material. A sealing surface extends around the circumferential wall of the body. The sealing surface is formed from a plurality of layers of a second material. The second material is harder than the first material. The piston can be within a downhole piston assembly that also includes a housing, and the piston being longitudinally movable in a bore in the housing. A method for producing a piston includes preparing a piston formed from a first material, with the piston including a first end. A sealing surface is applied to the piston using laser cladding, with the sealing surface including a second material harder than the first material. The sealing surface is finished to a sealing surface diameter.

A tunable wellbore pulsation valve reduces drillstring friction in a wellbore. An upper valve plate and a lower valve plate, and upper valve plate orifice and lower valve plate orifice enabling throughflow. A Moineau motor rotates the upper valve plate while the lower valve plate remains stationary. Fluid flow causes a first fluid state of fluid passing through both the upper valve plate and the lower valve plate when the fluid passing causes rotation of the upper valve plate to align the upper valve plate orifice with the lower valve plate orifice. Increased flow efficiency produces more powerful fluid pressure pulsations and axial vibrations without increasing pump pressure at the surface of the wellbore, yielding increased wellbore friction reduction while expending the same or less energy at the surface pump than would be expended in the absence of the reduced turbulent and shear conditions and increased laminar conditions.

A spallation drill head can include a drill head body having a primary face substantially oriented facing in a primary drilling direction along a longitudinal axis of the drill head body. A liquid inlet can be on the drill head body. The liquid inlet can be connected or connectable to a liquid supply line. An internal liquid connection can be oriented within the drill head body and fluidly connected to the liquid inlet. A plurality of liquid jets can be oriented on the primary face of the drill head. The liquid jets can be fed by the liquid inlet through the internal liquid connection. A mass flow controller can be associated with the liquid jets to control delivery of liquid by the liquid jet, and flowrates to at least two of the liquid jets can be independently controllable.

An acid tunneling system for forming lateral tunnels from a central wellbore. The acid tunneling system includes an acid tunneling tool having an acid injection nozzle which can be steered and oriented in response to downhole parameters that are detected and sent to surface in real time.

A jet flow adjustment method for rotary steerable downhole release relates to a technical field of downhole drilling equipment for oil wells, which includes steps of: defining a diversion ratio p of a jet nozzle (2) by a ground control system according to a cleaning requirement of a cuttings bed; and sending the diversion ratio p of the jet nozzle (2) to a control unit of a downhole rotary steerable system; and determining an opening area s of the jet nozzle (2) by the control unit of the downhole rotary steerable system according to the diversion ratio p of the jet nozzle (2) and an equivalent channel area S of a drilling tool, wherein a calculation formula is: s=p*S/(1−p); controlling an adjustable bypass valve (3) by the control unit of the downhole rotary steerable system according to the calculated opening area s of the jet nozzle (2), so as to control an overlapping area between sector holes (9) of a rotor end (7) and a stator end (8), thereby opening the jet nozzle (2) for release. The present invention has simple control and strong release ability, which can effectively solve the jamming problem of the rotary steerable downhole tool.

A tunable wellbore pulsation valve reduces drillstring friction in a wellbore. An upper valve plate and a lower valve plate, and upper valve plate orifice and lower valve plate orifice enabling throughflow. A Moineau motor rotates the upper valve plate while the lower valve plate remains stationary. Fluid flow causes a first fluid state of fluid passing through both the upper valve plate and the lower valve plate when the fluid passing causes rotation of the upper valve plate to align the upper valve plate orifice with the lower valve plate orifice. Increased flow efficiency produces more powerful fluid pressure pulsations and axial vibrations without increasing pump pressure at the surface of the wellbore, yielding increased wellbore friction reduction while expending the same or less energy at the surface pump than would be expended in the absence of the reduced turbulent and shear conditions and increased laminar conditions.

The present disclosure describes various embodiments, as well as features and aspects thereof, of an improved drill bit assembly for a percussion boring system. More specifically, one non-limiting embodiment of an improved drill bit assembly for a percussion boring system comprises a bit and a product engagement member. The bit comprises a slant faced head and at least one exhaust port. The product engagement member comprises a product coupling portion and at least one fluid restriction portion. This improved drill bit assembly is such that, when the product engagement member is detachably engaged with the slant faced head of the bit, a first portion of the fluid stream expelled from the bit is directed substantially forward of the slant faced head and a second portion of the fluid stream is directed substantially rearward from the slant faced head.

A spallation drill head can include a drill head body having a primary face substantially oriented facing in a primary drilling direction along a longitudinal axis of the drill head body. A liquid inlet can be on the drill head body. The liquid inlet can be connected or connectable to a liquid supply line. An internal liquid connection can be oriented within the drill head body and fluidly connected to the liquid inlet. A plurality of liquid jets can be oriented on the primary face of the drill head. The liquid jets can be fed by the liquid inlet through the internal liquid connection. A mass flow controller can be associated with the liquid jets to control delivery of liquid by the liquid jet, and flowrates to at least two of the liquid jets can be independently controllable.

A multi-functional jetting tool can be installed within a tubular work string, or attached to the distal or leading end of the tubular work string, in order to facilitate improved cleaning of downhole and/or subsea equipment—and particularly equipment with internal recesses, cavities or crevasses. A bull nose cap member, which can be constructed of plastic or other non-abrasive material, can be attached when the jetting tool is run on the distal end of a tubular work string. Fluid jetting ports can be selectively equipped with standard-sized or adjustable nozzles, thereby permitting customized fluid jet flow pattern from the jetting tool along the tool body in multiple directions for desired applications.