Importance

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Abstract

This invention involves a modification of the prior art subsea drilling system in which a carousel is positioned on a central post surrounded by a coaxial circular array of well slots and is adapted to be rotated by drill pipe through conventional means, from the floating platform. The carousel utilizes a fixed support platform spaced from the axis of rotation a distance equal to the radius of the array of well slots. The platform has its own well slot and a bearing concentric with the well slot. A well slot platform, or support post platform, is journaled in this bearing and supports a plurality of guide posts on a circle centered at the axis of the well slot. The support posts support cables hanging from the drilling vessel, which are used to guide the drill bit down from the surface to the carousel well slot. The carousel is adapted to revolve while supported by circular rails concentric with the central guide post. Means are provided, such as two gears of equal diameter, one fixed to the template concentric with the turning post, the other fixed to the well slot platform, with an intervening pinion so that as the carousel revolves in one direction by a selected angle, the well slot platform and support rods will rotate through an equal angle with respect to the carousel, in the reverse direction. Thus the guide posts and guide cables will always remain with the same azimuth as that of the drill ship. In this way the twisting and tangling of the support cables is avoided.

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First Claim