Telescoping casing joint for landing a casting string in a well bore

摘要

A casing joint is provided for use in landing a casing string in a well bore for an oil or gas well in a controlled manner so that movement of the casing string relative to the well bore does not cause the casing string to become damaged. The casing joint includes an inner tubular member disposed within an outer tubular member. The casing joint also includes a means for causing the inner tubular member to move axially relative to the outer tubular member in response to differential fluid pressures. The casing joint further includes a plurality of shear pins attaching the inner tubular member to the outer tubular member. The shear pins are selected to shear at a predetermined load so as to enable the inner tubular member to move axially relative to the outer tubular member. The casing joint also includes a pair of anti-rotation lugs which prevent the inner tubular member from rotating relative to the outer tubular member. In landing the casing string, the casing joint is placed into the well bore a predetermined distance above the bottom of the well bore. Mud is pumped through the casing joint at a high enough pressure to rupture the shear pins and cause the inner tubular member to extend to the bottom of the well bore. An annular stop ring limits the axial movement of the inner tubular member in the extended condition. Next, the casing joint is cemented into the well bore. The cement is then allowed to harden so that the casing joint bonds to the subsea formation surrounding the bottom of the well bore.