Method and apparatus for aligning a BOP stack and a mast

摘要

A method and apparatus for aligning a wellhead or BOP stack with a mast assembly comprising a sensor which provides an initial alignment between a mast and a wellhead or BOP stack. A mast assembly is transported to a well site by a rig carrier and positions the mast assembly adjacent a wellhead, or BOP stack. The mast assembly is raised to an upright position whereby a rear portion of the mast extends over the wellhead. In one embodiment, at least one sensor is mounted to a top drive and/or crown located within the mast assembly. The top drive has a predetermined path of movement and the sensor aligns itself with the wellhead. In another embodiment, at least one sensor is mounted to the wellhead and aligns itself with a laser alignment target fastened to a crown and/or top drive of the mast. In yet another embodiment, at least one sensor is located on a lower portion of the mast assembly to align the mast with the wellhead. The apparatus is designed to achieve an accuracy of alignment which in different embodiments could be less than 5 degrees, less than 3 degrees, or less than 1 degree.

主权项

1. An apparatus for aligning a mast assembly, comprising:
a rig carrier; a blow out preventer (BOP) stack comprising a bore, wherein said BOP stack is positioned above a wellhead and below said mast assembly; said mast assembly pivotally mounted to said rig carrier, wherein said mast assembly is moveable between a lowered position and an upright position with respect to said rig carrier, and wherein said mast assembly extends over a back end of said rig carrier when raised to said upright position; a top drive mounted on said mast assembly, wherein said top drive is constrained to move along a fixed axial path; and at least one sensor for aligning said fixed axial path of said top drive with an axis of said bore of said BOP stack for drilling operations, wherein said at least one sensor comprises a sender and a receiver respective of which are mounted to different elements selected from a group consisting of said mast assembly, said wellhead, a snubbing stack, a pressure control equipment, said BOP stack, and said top drive.