Abstract: A method and apparatus for unplugging a well or pipe obstructed by a gas hydrates. According to the invention, a moving heating element is applied against one end of the hydrate plug, and is displaced axially in the tube or the pipe towards the other end, so as to cause the plug to melt progressively from one end to the other. Application to the oil industry, in particular in off-shore wells.

Abstract: A radially deformable inflatable tubular sleeve for tubing or obturating a well (P) or a pipe. The sleeve includes a tube and a series of breakable restraining rings positioned along the tube. The rings are arranged so that each ring breaks one after the other in the longitudinal direction of the sleeve when the tube is inflated by an internal fluid under pressure. As a ring breaks, liquid (B) present in the well is moved progressively forward so as to prevent pockets forming on the outside of the tubing.

Abstract: The device includes a radially deformable flexible tubular preform (1) that can be expanded by internal pressure and hardened in situ by heating its wall to polymerize it, the preform is formed of a rectilinear main section (10 and a rectilinear secondary section (11) at an acute angle (.alpha.) to the main section (10) and joined and sealed to the latter in a middle area (10c), temporary restraining bindings being provided to hold the secondary section initially in a radially folded condition, pressed against the main section (10), the combination then constituting a rectilinear preform, whereas after removal of the temporary restraining bindings (3), and due to internal pressure, the secondary section (11) separates from the main section (10), the combination then constituting a generally "y" shape preform adapted to be polymerized in the area of bifurcation of the well.

Abstract: A casing is cemented within a well bore (P) or pipe by means of a radially expandable tubular preform (1). For this purpose, a) folded preform (1) is inserted into the well (P) or pipe down to the required level; b) the well is sealed off at the bottom of the preform (10 by means of an inflatable hydraulic retainer (4); c) a curable fluid cement is injected onto the retainer so that it surrounds the lower portion of the preform; d) the preform is gradually unfolded from the top towards the bottom to press the cement against the wall of the well or pipe along the full length of the preform; e) the preform is cured to form a casing while the cement is allowed to set; and f) the retainer (4) is deflated and withdrawn from the well or pipe.

Abstract: The tubular structure comprises at least a braid of flexible strands (10) comprising fibers (100) that cross over with a certain amount of play so that the structure is capable of expanding radially while shrinking axially when pressure is applied to the inside of the preform or the matrix.

Abstract: To seal the connection between an internal lining and external borehole, casing or pipeline, one or more elastically deformable annular seals are placed on the preform in a contracted state, in a configuration which does not impede insertion of the preform into the borehole, casing or pipeline. During expansion of the preform the seal itself forms an annular groove for receiving it in the exterior surface of the preform. After hardening of the preform a rigid lining is obtained having an integral seal. Applications include repair of boreholes, casings, especially in oil wells, or pipelines, by internal lining.