Hydraulic drilling rig

摘要

A multi-purpose drilling rig has a movable pipe support cradle which moves horizontally to transfer drill pipe from a storage area to the well being drilled, and vice versa. The cradle travels along a roof platform supported by load-bearing hydraulic lifting rams. Raising or lowering the lifting rams raises or lowers the roof platform, along with the drill pipe suspended from the cradle. Structural towers stabilize the lifting rams against buckling and lateral loads. Supplementary lifting capacity is provided cradle-mounted roof rams having pistons which may extend downward from the cradle, with the drill pipe suspended from a yoke interconnecting the roof ram pistons. For offshore drilling, a control system senses fluctuations in rig elevation due to wave action, and automatically adjusts extends or retracts the rams as required to maintain constant load on the drill bit. Also disclosed is a method of drilling which utilizes vertical and lateral movement of the cradle and top drive.