A subsea hydrocarbon flowline system (300) is disclosed. The flowline system has a hydrocarbon flowline (302); an electric trace heating system (304) arranged along at least a part-length of the flowline to control the temperature of hydrocarbon fluid flowing in the flowline; and a power input connector (Pin) configured for receiving electrical power from an electrical power providing system for powering the electric trace heating system. The electric trace heating system has a first three-phase trace heating cable (C′) and a second three-phase trace heating cable (C″), each trace heating cable extending between the power input connector and a cable termination (T′; T″) where phase conduits (L1′, L2′, L3′; L1″, L2″, L3″) of the trace heating cable are Y-connected and terminate in a neutral connection point (L.sub.N′; L.sub.N″). Further, the flowline system has a power output connector (Pout) for providing electrical power to a subsea hydrocarbon production system; a first electrical conduit (306′) extending between the neutral connection point of the cable termination of the first trace heating cable and the power output connector; and a second electrical conduit (306″) extending between the neutral connection point of the cable termination of the second trace heating cable and the power output connector, wherein the first and the second electrical conduits are electrically accessible at the power output connector for powering the subsea hydrocarbon production system.

A power and communications cable may include an electromagnetic waveguide, an inner metallic tubular surrounding the electromagnetic waveguide, an electrically conductive material surrounding the inner metallic tubular, an electrically insulating material surrounding the electrically conductive material, and an outer metallic tubular resistant to corrosion and abrasion surrounding the electrically insulating layer. The example system may include an electrical device locatable in the wellbore and coupleable to the cable and a control unit coupleable to the cable and operable to supply power to and communicate with the electrical device via the power and communications cable.

A method comprises monitoring a resistance over time of a tubing encased conductor (TEC) that electrically connects a first downhole gauge to a second downhole gauge positioned in a borehole deeper than the first downhole gauge. The method includes detecting that a first TEC fault has occurred in the TEC, in response to a change in the resistance being greater than a fault occurrence threshold and in response to an amount of the time of the change being smaller than a fault time threshold.

An electrical tool for well stimulation includes a first electrode and a second electrode. The second electrode being at the level of a first segment and a second segment of the tool. A peripheral electrode insulated electrically from the first electrode. The first segment and the second segment are linked by an articulated link inside which is arranged a coaxial cable running from the first segment to the second segment. The coaxial cable includes an electrically conducting outer envelope insulated electrically from an electrically conducting central core. The tool includes a first electrical contact between the central core of the coaxial cable and the first electrode, and a second electrical contact between the outer envelope of the coaxial cable and the second electrode.

An apparatus for communicating a signal to or from a downhole tool includes a drill pipe configured to be rotated to drill a borehole, a tubular under axial tension and secured in the drill pipe, and a retention device secured to the tubular and configured to maintain the tubular under the axial tension. The retention device includes a portion extending from a body of the device in a direction that is non-inward-radial with respect to a longitudinal axis of the drill pipe. The apparatus further includes a transmission line disposed in the tubular and in an opening of the retention device and in communication with the downhole tool.

Systems including wellbore tubing having an anchor assembly, an upper control line connector coupled to the anchor assembly, a first housing, and a first connector. The first connector provides a first angular mating face that faces tangentially with respect to the first housing, an upper control line operatively coupled to the first housing, and first communication media that extend through the first housing to the first angular mating face. A completion assembly within a wellbore has a completion receptacle to receive the anchor assembly, a lower control line connector coupled to the completion receptacle and a second housing and a second connector. The second connector provides a second angular mating face that faces tangentially with respect to the second housing, and a lower control line operatively coupled to the second housing and one or more second communication media that extend through the second housing to the second angular mating face.

A gap sub assembly for electromagnetic telemetry used in downhole drilling. The gap sub comprises a female part comprising a female mating section and a male part comprising a male mating section. The male mating section is matingly received within the female mating section and electrically isolated therefrom. One or more electrically insulating bodies secure the male part axially and torsionally relative to the female part. The electrically insulating bodies also electrically isolate the male part from the female part. The electrically insulating bodies can be installed through apertures in the female part or at least some of the electrically insulating bodies can be installed before the male mating section is inserted into the female mating section. The electrically insulating bodies can be held in place on the male mating section using a retention apparatus such as a ring, a scarf, pods or an adhesive.

The disclosure relates to an electrocrushing drilling fluid with an electrocrushing drilling base fluid including a non-polar oil, water, and glycerin. The base fluid may further include a polar oil and an alkylene carbonate. The electrocrushing drilling fluid may further contain at least one additive. The electrocrushing drilling fluid may have a dielectric constant or dielectric strength of at least a set amount, an electric conductivity less than a set amount, or a combination of these properties. The disclosure further relates to an electrocrushing drilling system containing the electrocrushing drilling fluid and an electrocrushing drill bit.

A downhole communication system includes a gap sub located at an RSS. The gap sub is located on the outer, independently rotating member of the RSS. This allows the RSS to receive electromagnetic downlink communication signals from the surface or from an MWD. The RSS transmits electromagnetic uplink signals to a second gap sub located above the RSS or to the surface.

A carrier pipe is protected from corrosion by being received inside a casing at a location above ground. The casing, which can be formed from a polymer, defines a gap extending around an exterior surface of the carrier pipe. In one embodiment, the gap is substantially filled with a potting material having a corrosion-resistant property. In another embodiment, a self-contained impressed current cathodic protection system is received in the gap. A pull head is installed on the carrier pipe and/or casing for pulling the pipe assembly, including carrier pipe, casing, and elements received in the gap, into an underground bore as a single unit. In some embodiments multiple pipe assemblies are pulled together into the same bore.