Liner hanger

Abstract

Liner hanger to be placed in an existing casing with a flexible expansion seal ( 180 ) and a metallic gripping element ( 190 ) disposed on inclined surfaces such that they are moved radially when a leadscrew nut ( 130 ) is moved axially relative to an inner, hollow shaft ( 150 ). The lead screw nut is moved axially when a lead screw is rotated therein, and the lead screw is rotatably disposed around the inner, hollow shaft ( 150 ).

1 - 4 . (canceled) 
     
     
         5 . A liner hanger to be placed in an existing casing, the liner hanger comprising an inner, hollow shaft, having, in a first end, grooves configured to receive second latching dogs for latching to an external drive shaft and having, in a second end, threading for connecting a section of pipes, wherein the inner shaft is supported coaxially in an outer housing comprising a flexible expansion seal and a radially movable metallic gripping element disposed on inclined surfaces configured to be moved axially by a leadscrew nut which is axially movable relative to the inner shaft, and wherein the leadscrew nut is provided with lead screw threading on an inner surface, characterized in that
 the inner shaft is rotation locked relative to the outer housing,   that the liner hanger further comprises a torque transmitting sleeve rotatably disposed around, and axially locked relative to, the inner shaft, and   that the torque transmitting sleeve has external lead screw threads disposed in the lead screw nut and additional grooves adapted to first latching dogs for rotational locking against a separate part of the external drive shaft.   
     
     
         6 . The liner hanger according to  claim 5 , wherein the flexible expansion seal is preloaded by spring elements. 
     
     
         7 . A method for suspending a section of pipes from an existing casing, comprising:
 connecting an inner hollow shaft to a section of pipes,   suspending the shaft from a drive shaft using second latching dogs and corresponding grooves,   lowering the inner shaft until its upper end overlaps the lower end of the casing,   rotating a leadscrew on a torque transmitting sleeve around the inner hollow shaft using first latching dogs rotatably fixed to the leadscrew, the leadscrew having threads engaging corresponding threads on a lead screw nut rotationally locked to the shaft, thereby moving the leadscrew nut axially along the shaft, the leadscrew nut causing a metallic gripping element and an expandable seal to engage the inner surface of the casing,   transferring the weight of the section of pipes from the second latching dogs to the metallic gripping element,   releasing the latching dogs, and   retracting the drive shaft axially from the assembly comprising the inner hollow shaft.