Downhole apparatus and methods

A well construction apparatus for use in lining a drilled bore, the well construction apparatus comprising:

• a liner having a wall and a fluid port in an upper portion of the wall;
• an inner string for extending to a distal end of the liner;
• and
• a telescopic section in the inner string between extended and retracted configurations, in one of the configurations the telescopic section being capable of transferring torque and in the other of the configurations the telescopic section permitting independent rotation of portions of the inner string above and below the telescopic section;
• whereby fluid may be pumped through the inner string, through a distal end of the liner to at least partially fill an outer annulus surrounding the liner, and from the outer annulus through the port in the liner and into an inner annulus between the inner string and the liner;
• and
• wherein the fluid port is configurable in an open configuration and in a closed configuration.

A well construction method comprising:

• providing a tubing assembly comprising bore-lining tubing and an inner string extending to a distal end of the tubing;
• advancing the tubing assembly into a drilled bore;
• permitting fluid displaced from a distal portion of the bore by the advancing tubing assembly to flow from an outer annulus surrounding the bore-lining tubing through a port in the tubing and into an inner annulus between the inner string and the tubing;
• locating the port in the liner such that when the liner is run into the bore the port is located below a section of overlap between a distal end of a previous casing and a proximal end of the liner;
• opening or closing the port;
• and
• providing a telescopic section in the inner string and reconfiguring the telescopic section between extended and retracted configurations, in one of the configurations the telescopic section being capable of transferring torque and in the other of the configurations the telescopic section permitting independent rotation of portions of the inner string above and below the telescopic section.

A well construction apparatus comprising:

• a tubing assembly including:
• bore-lining tubing having a wall and a fluid port in the wall, and
• an inner string extending to a distal end of the bore-lining tubing,
• whereby fluid displaced by advancing the tubing assembly into a drilled bore flows from an outer annulus surrounding the bore-lining tubing through the port in the tubing wall and into an inner annulus between the inner string and the tubing;
• wherein the fluid port is configurable in an open configuration and in a closed configuration;
• and
• wherein the bore-lining tubing is run into the tubing assembly with the fluid port in the closed configuration.