An umbilical (2) has a center tube (4) that is a steel tube, and that the cross section of the center tube (4) at the extremity of the umbilical (2) is made corrugated on a length that extends substantially from the extremity to a distance from the extremity so that fatigue strain on non corrugated parts of the steel tube is avoided when the extremity of the umbilical (2) is inserted into a bend stiffener (1).

An application tool may be coupled to a coiled tubing for performing an operation in a wellbore includes a rigid outer body and at least one flow tube. The rigid outer body includes a first material. The flow tube defines a flow path through the outer rigid body for receiving a corrosive fluid from the coiled tubing after the coiled tubing is coupled to the application tool. The flow tube includes a second material that is corrosion resistant and different than the first material.

The present invention provides a method for producing hydrocarbon gas from a wellbore and a control valve assembly for said wellbore. The wellbore comprises a wellhead, a production zone, a production tubing, and a velocity string installed inside the production tubing. The method comprises allowing gas to flow from the production zone through the velocity string, said gas forming a primary gas stream, and controlling the flow of gas from the annulus between the outer wall of the velocity string and the inner wall of the production tubing to the primary gas stream by means of the control valve wherein a controlled mass flow of said gas is combined with the primary gas stream.

Systems and methods for managing pressures present in an annular space defined between casing strings contained within a subterranean well. These systems and methods may include providing a pressure distribution casing that includes a plurality of pressure distribution passages and distributing fluids present within the annular space along a length of the pressure distribution casing and/or between the annular space and the subterranean formation using a portion of the plurality of pressure distribution passages. Pressure distribution passages may be present on an inner surface of the pressure distribution casing, on an outer surface of the pressure distribution casing, and/or within a wall of the pressure distribution casing and may distribute the fluids along the length of the pressure distribution casing without distributing the fluids across and/or through a wall of the pressure distribution casing, such as between the inner surface and the outer surface of the pressure distribution casing.

An application tool may be coupled to a coiled tubing for performing an operation in a wellbore includes a rigid outer body and at least one flow tube. The rigid outer body includes a first material. The flow tube defines a flow path through the outer rigid body for receiving a corrosive fluid from the coiled tubing after the coiled tubing is coupled to the application tool. The flow tube includes a second material that is corrosion resistant and different than the first material.

A method of making a fluid conduit includes at least one tubular metal fitting in fluid communication with metal tubing. The conduit is apt to be incorporated into a subsea umbilical. The fitting is made by cold-forming a workpiece in a spinning operation. The workpiece material initially has a yield strength below that of the tubing material. The invention corrects or reduces this mismatch between the yield strength of the tubing material and the initial yield strength of the workpiece material by: assessing the yield strength of the tubing material; assessing the increased yield strength of the workpiece material by virtue of the spinning operation; and before welding the fitting to the tubing, comparing the increased yield strength of the workpiece material with the yield strength of the tubing material.

A length of tubing and related apparatus and methods are described, where the length of tubing is deployable from a coiled configuration to an uncoiled configuration for performing a coiled tubing operation in a wellbore. The length of tubing includes a pipe of metal, and a liner of composite material that lines the pipe. The liner or the lined pipe includes a wall structure that incorporates means to communicate at least one service along the tubing.

Disclosed are methods and apparatus for preventing corrosion within the annulus of a flexible pipe used in a riser in an offshore hydrocarbon production facility. Buffer fluid comprising a passivating agent is introduced into the annulus to form protective layers on metal surfaces within the annulus to resist corrosive materials from contacting the metal surfaces. The passivating agents may be one or more of a polyalphaolefin, a polybutene, or a polysiloxane. A corrosion inhibitor may be combined with the passivating agent in the buffer fluid. Pretreating of the metal surfaces within the annulus prior to introduction of the buffer fluid can be performed with a pretreating corrosion inhibitor.