Patent ID: 6196322
Filing Date: 2001-03-06
Classification: E21B

Abstract:
An underwater installation for offshore drilling of a hydrocarbon well or wells in the seabed in deep and moderately deep water for the production of hydrocarbons from a reservoir below the seabed, the well or wells having an exposed casing or casings on the seabed, said installation comprisingan intermediate station in the form of a buoyancy based hollow body, said body being totally submerged below the surface of the water and above the seabed at a depth at which the influence from waves is small, said hollow body being positioned over the well or wells;a tension leg anchoring means for anchoring the hollow body to the seabed over the well or wells, said anchoring means comprising at least one hydrocarbon conveying pipeline formed of a casing extension pipe string extending between, and being coupled to, the exposed casing or casings of the well or wells on the seabed and the hollow body for forming a tension leg anchoring means for the hollow body and for transferring hydrocarbons from the reservoir in the seabed to the hollow body, said tensioning leg anchoring means forming the sole means for anchoring said submerged hollow body to the seabed; andmeans for supplying hydrocarbons from the hollow body to the surface of the water.