Rigid wound or reelable pipe (1) for transporting hydrocarbons having a single-walled or double-walled envelope comprising two coaxial pipes, internal (2) and external (3), respectively, separated by an annular space, comprising at least one electrical heating cable (10) capable of being subjected to an elongation of 0.5% without sustaining damage and produced, for example, in the form of a central conducting braided cable surrounded by an electrically insulating sheath. The materials comprising the cable are subjected to elastically deformation by remaining below 15% of their elastic limit and preferably below 5%.

An elongated object for use in subsea having a heating pipe and an electrical cable fixed to the surface of the heating pipe. The electrical cable has a protective sleeving for surrounding the electrical cable, composed of a series of elongated synthetic plastics components arranged end-to-end. Each component is an extruded frame work type hollow profile suitable for slowing down the impact over a long deformation path. A hollow space is disposed between the electrical cable and the protective sleeving allowing the cable to move into the protective sleeving.

A method for manufacturing an electrical cable provides an electrical cable suitable for use in heating wells. An elastomeric jacket is extruded over insulated conductors. A stainless steel plate is rolled around the jacket to form a cylindrical coiled tubing having a seam. The seam is welded, then the tubing is swaged down to a lesser diameter to cause the tubing to frictionally grip the jacket. A recess maybe formed in the jacket adjacent the seam to avoid heat damage from the welding process.

Wellhead assembly and method for providing power connection to downhole electrical device. Wellhead body members support vertically stacked isolated tubing hanger and grounding tubing hanger. The isolated tubing hanger suspends a conducting tubing string, while the grounding tubing hanger suspends a grounding tubing string concentrically spaced from the conducting tubing string. The isolated tubing hanger has an outer housing, an inner electrically conducting portion supported by the outer housing to provide electrical connection with, and suspend, the conducting tubing string, and insulation between the housing and conducting portion to electrically isolate the housing. Hot electrical connection is made through a conduit in the wellhead body member, for electrical connection to the conducting tubing string. Grounding connection is provided to the wellhead body members.

Wellhead assembly and method for providing a power connection to a downhole electrical device, such as a heater. Pressure-containing wellhead body members enclose a vertical wellbore and support therein an isolated tubing hanger and a grounding tubing hanger. The isolated tubing hanger suspends a conducting tubing string, while the grounding tubing hanger suspends a grounding tubing string concentrically spaced from the conducting tubing string. The isolated tubing hanger has an outer housing, an inner electrically conducting portion supported by the outer housing operative to provide electrical connection with, and suspend, the conducting tubing string, and insulation between the housing and conducting portion to electrically isolate the housing portion. Hot electrical connection is made for electrical connection to the conducting portion of the isolated tubing hanger or the conducting tubing string. Electrical isolation seals and electrically isolates the hot electrical connection from the wellhead body members. Grounding connection is provided to a wellhead body member. A source of current provides a first connection to the hot electrical connection and a second connection to the grounding connection.