A downhole valve assembly including a valve mounted in a tubular body, the valve moveable between an open and closed position. Movement is achieved by a fluid operated valve actuation mechanism located downhole of the valve having a fluid inlet port located uphole of the valve. A method of controlling fluid flow downhole is also described allowing the valve to be moved between the open and closed positions and between closed and open positions.

A drilling method comprises advancing a drill string through a cased section of a wellbore. The drill string comprises an expandable tubular, a drill assembly having a drill bit, and a tubing expander. The expandable tubular is advanced through the wellbore below the cased section, and at least a portion of the expandable tubular is expanded into the drilled wellbore using the expander. The expandable tubular does not overlap the cased section of the wellbore.

Methods and apparatus for shaping pipes, tubes, liners, or casing (200) at downhole locations in wells. Use is made of rollers (116) bearing radially outwards against the inside wall of the pipe (etc.), the rollers being rolled around the pipe to cause outward plastic deformation which expands and shapes the pipe to a desired profile. Where one pipe (180) is inside another (190), the two pipes can be joined without separate components (except optional seals (208)). Landing nipples and liner hangers can be formed in situ. Valves can be deployed to a selected downhole location and there sealed to the casing or liner without separate packers. Casing can be deployed downhole in reduced-diameter lengths and then expanded to case a well without requiring larger diameter bores and casing further uphole. The invention enables simplified downhole working, and enables a well to be drilled and produced with the minimum downhole bore throughout its depth, obviating the need for large bores. When expanding lengths of casing, the casing does not need to be anchored or made pressure-tight. The profiling/expansion tools (100) of the invention can be deployed downhole on coiled tubing, and operated without high tensile loads on the coiled tubing.

A method of providing a downhole seal in a wellbore having a lined portion is provided. A tubular having a polished bore portion and an expandable portion is run into the wellbore and suspended at a selected depth within the wellbore, such that at least the expandable portion of the tubular is in an overlapping relationship with the lined portion of the wellbore. The expandable portion of the first tubular is expanded into frictional engagement with the lined portion of the wellbore.

Apparatus for completing a subterranean wellbore and associated methods of using provide relatively uncomplicated and convenient access to a parent wellbore lower portion from a lateral wellbore liner which extends into the parent wellbore above the lower portion. The apparatus is utilized to form an opening through a portion of the liner which overlies the parent wellbore lower portion, thereby providing access thereto. In a preferred embodiment, the apparatus includes a milling guide having an axially extending guide profile formed therein, which guide profile is capable of directing a mill toward the liner portion to form the opening. The milling guide is capable of being anchored in the liner to thereby fix its axial and rotational alignment relative to the liner portion.

A method for milling within a whipstock set in a wellbore comprises introducing a mill guide (30) having a channel therethrough into the wellbore above the whipstock. The mill guide is moved into stabilising contact with the whipstock and a mill is guided by the mill guide to mill down into the whipstock. The mill has at least a portion thereof in contact with the mill guide while milling into the whipstock.

Apparatus for completing a subterranean wellbore and associated methods of using provide relatively uncomplicated and convenient access to a parent wellbore lower portion from a lateral wellbore liner which extends into the parent wellbore above the lower portion. The apparatus is utilized to form an opening through a portion of the liner which overlies the parent wellbore lower portion, thereby providing access thereto. In a preferred embodiment, the apparatus includes a milling guide having an axially extending guide profile formed therein, which guide profile is capable of directing a mill toward the liner portion to form the opening. The milling guide is capable of being anchored in the liner to thereby fix its axial and rotational alignment relative to the liner portion.