A wireline system includes a control system, a downhole tool, and a wireline cable coupling the downhole tool and the control system. The wireline cable includes a plurality of conductors, which includes a core conductor and a concentric conductor disposed around the core conductor, wherein two of the plurality of conductors form a conductor pair, and wherein each of the plurality of conductors is configured to transmit power, data, or both, between the control system and the downhole tool. The wireline cable further includes one or more insulative layers, wherein at least one insulative layer is disposed between any two conductors.

An improved gap sub assembly that can withstand the rigors of directional drilling, while still being cost effective and easy to deploy at the drill site. Embodiments can be assembled by sliding a mandrel into a housing without any threading or clocking, filling the gap between the housing and mandrel with an electrically isolating material, and curing the electrically isolating material to mechanically couple the housing and mandrel. In some embodiments, the interior surface of the housing and the outer surface of the mandrel comprise a plurality of complimentary axial sections having staggered diameters so that a constant dielectric gap is maintained. In some embodiments, the interior surface of the housing and the outer surface of the mandrel comprise non-overlapping right- and/or left-handed helical grooves that, when filled with a cured electrically insulating material, forms a complex 3D shear resistance mechanism optimized to resist torsion or twisting.

An electromagnetic perforation device for well casings includes a coil disposed around a core carried by a mandrel. The device further includes a power supply coupled to a current supply device, which is coupled to said coil. A stabilizing member extends from the mandrel and spaced apart on the mandrel from the coil core. The electromagnetic performance device may be positioned in a well casing, and the current supply device may rapidly supply a current to the coil to created an electromagnetic field in the coil and simultaneously induces a magnetic field in the well casing. The coil, current, and well casing may be selected such that electromagnetic field and the magnetic field produce repulsive magnetic forces that are sufficient to overcome a yield strength of the well casing and perforate the well casing.

A drilling system including a drill string, an EM telemetry assembly, and an electric contact assembly that defines an electrical connection with the drill string. The electric contact assembly permits a portion of the EM tool to slide along a portion of the drill string during drill string assembly.

A radio frequency (RF) and fluid coupler is for a subterranean assembly. The assembly may have a fluid passageway therein, and may include an RF antenna and a coaxial transmission line connected thereto. The coupler may include an electrically conductive hollow body that includes electrically conductive segments connected together in end-to-end relation at respective joints to provide an outer electrical pathway to connect to the outer conductor of the coaxial transmission line. An elongate conductive member may extend within the electrically conductive hollow body to provide an inner electrical pathway to connect to the inner conductor of the coaxial transmission line. A respective dielectric pressure barrier may be between the elongate conductive member and adjacent portions of the electrically conductive hollow body adjacent each of a pair of joints to define a fluid chamber to connect to the fluid passageway. A fluid port may be connected to the fluid chamber.

A safety waveguide apparatus includes a waveguide segment body sealed by a respective dielectric plug on each end of the waveguide body. The waveguide segment body, or at least one of the dielectric plugs, are configured to divert an oil flow from within the waveguide segment body.

The invention addresses protecting the free ends of communication lines from debris during downhole wet-mate connection in a wellbore, with protection of the lines upon disconnection as well. A reciprocating debris exclusion device is provided for use with upper and lower tools to be connected. The lower tool has a reciprocating cover member mounted for sliding engagement with the housing of the lower tool, the cover member shielding the free end of a communication line. An upper tool has a bladder-type cover member attached to the upper tool and protecting the free end of a communication line. The reciprocating cover member is moveable between a closed and an open position and is moved in response to contact with the upper tool. The bladder cover is movable between closed and open positions and is moved to the open position by contact with the reciprocating cover member of the lower tool.

A subterranean radio frequency (RF) heating system includes a first tubular member having a first end, a second end, and an inner surface. A second tubular member is arranged radially inwardly of the inner surface of the first tubular member. The second tubular member includes a first end portion, a second end portion, and an outer surface portion. A first electrically insulated spacer is arranged between the inner surface of the first tubular member and the outer surface portion of the second tubular member adjacent the first end and first end portion. A second electrically insulated spacer is arranged between the inner surface of the first tubular member and the outer surface portion of the second tubular member adjacent the second end and the second end portion.

An electric cable for powering a downhole tool in a wellbore. The electric cable includes a core including one or more electrically conductive wires and one or more electric insulating layers surrounding the conductive wires; a metal inner tube surrounding the core, where the metal inner tubing and the core includes one or more undulated segments with one or more curved outer extensions projecting outwards from a longitudinal axis of the electric cable; and an outer encapsulating tube surrounding the core and metal inner tube, where the outer surface of the metal inner tube has outermost portions at the curved outer extensions of the undulated segments that touch an inner surface of the outer encapsulating tube. A well system including the electric cable and a method of assembling the electric cable are also disclosed.

Downhole electrical energy harvesting and communication in systems for well installations having metallic structure carrying electric current, for example CP current. In some instances there is a harvesting module (4) electrically connected to the metallic structure (2) at a first location and to a second location spaced from the first location, the first and second locations being chosen such that, in use, there is a potential difference therebetween due to the electric current flowing in the structure (2); and the harvesting module (4) being arranged to harvest electrical energy from the electric current. In addition or alternatively, there may be communication apparatus (4, 5, 6) for communication by modulation of the current, for example CP current, in the metallic structure (2).