Liner hanger with improved bite and method

Abstract

An improved liner hanger is provided suitable for use with conventional slips to interconnect a downhole casing with a smaller-diameter liner. The hanger comprises an outer cone sleeve and an inner locking sleeve, with the cone sleeve interconnected with the conventional slips, and the locking sleeve having right-hand and left-hand inner biting threads for engagement with the outer surface of a tubular liner section. Improved mating threads are provided on the outer surface of the locking sleeve and the inner surface of the cone sleeve. The cone sleeve and locking sleeve are initially made up at the surface with the apexes of the tapered thread profiles substantially in axial alignment. After the liner hanger is initially positioned downhole, an axially directed downward force on the locking sleeve causes the locking sleeve to slide along the tapered surface of its thread profile with respect to a corresponding tapered surface on the thread profile of the cone sleeve, thereby shifting the apexes out of alignment and moving the biting threads radially inward for increased gripping engagement with the tubular liner section. Stop surfaces on both the locking sleeve and the cone sleeve limit axial movement of the locking sleeve with respect to the cone sleeve and thus prevent excessive radial force, which could otherwise cause failure of the liner hanger components or crush the liner.