Abstract: A diverter or rotary drill head has a rubber stripper assembly mounted to a stinger flange. An annular retaining collar is releasably received within the upper marginal end of the drill head main body. the retainer collar is axially spaced from a shoulder formed on the main body to form an annular area therebetween within which the stinger flange is rotatably received in low friction relationship. The retainer collar is held in assembled position by a plurality of retractable radially spaced dogs. The dogs are retracted to permit the stripper rubber, stinger flange, and stinger to be lifted free of the main body. This enables repairs to be rapidly and economically effected on the rotating parts of the diverter and provides a seal means by which well blow-outs can be diverted away from the drilling rig.

Abstract: A semi-submersible drill rig structure includes a ring-like enclosure surrounding a central drilling axis. In the structure are magazines holding drill string elements vertically. Lifting means on the structure raise the vertical drill string elements from their magazines and carry them to the drilling axis. A guide ring is displaceable to and from the drilling axis, in synchronism with the lifting means, to restrain the lower end of each raised element against pendulation. The magazines are rotatable about vertical axes to bring the individual elements under the line of movement of the lifting means and guide ring. Well casing elements are similarly restrained by the guide ring as they also are carried in a vertical orientation to the drilling axis. The disposition of the magazines in a structure surrounding the drilling axis provides a relatively calm region through which the drilling operations can be conducted.