Drilling assembly

Abstract

A drilling machine and relatively small mast are mounted on a pivotal support which permits the drilling machine, mast and drill pipe employed in the assembly to be inclined as required to drill a non-vertical bore hole. The drilling machine is preferably a fluid pressure-operated snubber device which includes a stationary lower gripping head and a vertically reciprocable, upper gripping head operable for rotating drill pipe and for running the drill pipe into and out of the well bore. An internal drill string anchor carried by a traveling block suspended in the mast engages and supports the upper end of the drill string extending from the snubber and also provides drilling fluids to the string. A rotatable seal and support assembly in the anchor maintains a fluid seal and permits the drill pipe to rotate relative to the non-rotating traveling block. The anchor is equipped with slips which grip the internal surface of the drill string and are positively moved into and out of gripping engagement with the drill string by hydraulic controls. A spring bias is provided on the slips to urge the slips into their gripping position and means are provided which increase the gripping force of the slips in response to an increase in the forces tending to separate the drill string from the anchor.