Abstract: A downhole apparatus comprises a plurality of tubing sections. Each tubing section has substantially cylindrical end portions initially of a first diameter for coupling to end portions of adjacent tubing sections. The end portions are expandable to a larger second diameter. Each tubing section also has an intermediate folded wall portions initially in a folded configuration. The intermediate folded wall portions are unfoldable to define a substantially cylindrical form of a third diameter.

Abstract: The present invention provides a method and apparatus for deforming a tubular body, running the tubular body through a restriction in a wellbore, reforming the tubular body, and expanding at least a portion of the tubular body past its elastic limit. In one aspect, the present invention provides a method for forming a substantially monobore well involving deforming a tubular body, running the tubular body below a restricted inner diameter portion, reforming the tubular body, and expanding at least a portion of the tubular body past its elastic limit. The restricted inner diameter portion may comprise a casing string previously disposed within the wellbore or a casing patch. The at least the portion of the tubular body expanded past its elastic limit may be a lower portion of the tubular body. Subsequent tubular bodies may be reformed and expanded below previous tubular bodies.

Abstract: A method of increasing the collapse resistance of a tubular comprises locating a tool having at least one, and typically three, bearing members within a tubular. The bearing members are positioned in engagement with a wall of the tubular to apply a radial force to a discrete zone of the wall. This radial force is then applied to further discrete zones of the wall, the level of radial force being selected such that the collapse resistance of the tubular is increased.

Abstract: A downhole apparatus comprises a plurality of tubing sections. Each tubing section has substantially cylindrical portions initially of a first diameter for coupling to end portions of adjacent tubing sections. The end portions are expandable to a larger second diameter. Each tubing section also has an intermediate folded wall portions initially in a folded configuration. The intermediate folded wall portions are unfoldable to define a substantially cylindrical form of a third diameter.

Abstract: An expandable coupling arrangement for coupling first and second tubulars includes a male thread portion on an end of the first tubular and a female thread portion on an end of the second tubular. The thread portions comprise dovetail threads having flanks, roots and crests, wherein the flanks are inclined at an angle of greater than 10°.

Abstract: A method of lining and drilling a bore (10) comprises the steps: mounting a first section of bore-lining tubing (20) on the lower end portion of a drill string (18); running the drill string and tubing into a bore having an unlined section and an existing tubing lined section; locating the first tubing section (20) in the unlined section: uncoupling the first tubing section (20) from the drill string (18); and drilling the bore beyond the first tubing section.

Abstract: A method of lining a drilled bore comprises running an expandable first tubular into a bore and locating part portion of the first tubular in an unlined section of the bore and another portion of the first tubular overlapping a portion of an existing second tubular. The first tubular is secured relative to the second tubular while retaining the provision of fluid outlets to permit displacement of fluid from an annulus between the first tubular and the bore wall. An expansion device is then run through the first tubular to expand the first tubular to a larger diameter. Cement is then circulated into the annulus between the expanded first tubular and the bore wall. The fluid outlets are then closed.

Abstract: A downhole apparatus comprises a plurality of tubing sections. Each tubing section has substantially cylindrical portions initially of a first diameter for coupling to end portions of adjacent tubing sections. The end portions are expandable to a larger second diameter. Each tubing section also has an intermediate folded wall portions initially in a folded configuration. The intermediate folded wall portions are unfoldable to define a substantially cylindrical form of a third diameter.