Method for lightening a riser pipe with optimized wearing part

摘要

A riser pipe for drilling an offshore well comprises a main tube extending the well up to a floating support, an auxiliary line being arranged parallel to main tube (4a, 4b). The auxiliary line comprises tubular sections (7a, 7b) made of steel and assembled end to end with a sliding fit by means of a tubular end part (25). According to the invention, a material, a titanium alloy for example, having an elastic limit at least 25% higher than that of the steel tubular sections (7a, 7b), is selected to manufacture said end part (25), and the end part as well as the end of said sections are dimensioned by taking account of the elastic limit of said material so as to reduce the sealing section of the end part.

主权项

1. A method for producing a lightweight riser for offshore well drilling, the riser comprising a main tube extending up to a floating support, at least one auxiliary line being arranged parallel to the main tube, the at least one auxiliary line comprising tubular steel sections assembled end to end, each section of the tubular steel sections being connected to an adjacent section of the tubular steel sections by an end part, each end of the tubular steel sections being provided with a female connection, the end part being secured inside the female connection of the end of a section of the tubular steel sections and mounted with a sliding fit in the female connection of the end of another section of the tubular steel sections wherein the ends of the adjacent tubular steel sections are spaced apart by the end part, a seal being arranged between the end part and the section of the tubular steel sections at a level of the sliding fit, wherein the end part is selected to comprise a material having an elastic limit at least 25% higher than the elastic limit of the steel of the tubular steel sections, and the end part and the ends of the tubular steel sections are dimensioned by accounting for the elastic limit of the material so as to reduce an outer section of the end part at the level of the seal.