Abstract: A drill rig installation has, for handling the elongate tubular well elements, a handling boom provided with grabs to lift the tubulars from the strongbacks and present them at the drilling axis. For this purpose the boom has pivot mountings for movements about a vertical axis and a horizontal axis respectively, and the grabs are displaceable transversely of the boom. A support pad for the tubular elements is transversely displaceable on the boom jointly with the grabs. The installation further comprises a grid-form base providing a fixed platform on which a drilling derrick can be slid to different grid positions to drill a series of bore holes. The base grid also carries the store of tubular elements and trolleys that register the elements with the handling boom, and other ancillary equipment such as slips and torque wrench machines for assembling and dismantling drill strings.

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.