Verfahren und Vorrichtung zum Durchfuehren von Arbeiten an Unterwasser-Tiefbohrungen

982,496. Wells &c. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. May 21, 1963 [May 23, 1962], No. 20247/63. Heading E1F. [Also in Division H4] Operations are carried out on an underwater well by mounting a submersible self propelled pipe manipulator on the lower end of a pipe string, moving the string and manipulator through the water in the vicinity of the wellhead of the well, determining the position of the string relative to the wellhead, moving the lower end of the string into alignment with the top of the wellhead, lowering the manipulator to slot on the well head, and lowering the pipe into the well. One form of slightly buoyant manipulator shown in Fig. 12 comprises propeller unit 42, 43, 51, 52, adjustably mounted television cameras 53, 54, flood-lights 63, 64, sound-transmitting and sound receiving means 65, 66 for locating the well, remotely operable latches 120, 121 for engagement with a flange 75 on a drill string 20, and a cable 50 electrically connected to the components. The wellhead 27 comprises an aligning cone 36, gas filled spheres (not shown) forming acoustic reflectors, and a transponder (not shown). Fig. 5 shows a manipulator 38 having a tendency to sink supported from a vessel 11 by a drill string 20. The manipulator is brought into axial alignment with the wellhead by means of the cameras and propellers, the string is lowered into the well for drilling and the manipulator is slid along the string to the vessel. In jet driven modifications of the manipulator a radial slot extends from the string receiving bore to permit removal of the manipulator from the string, and a sleeve for engaging the string is supported by arms from the manipulator which is adapted to engage an aligning cone at the side of the well. A non-buoyant manipulator having slips instead of latches is adapted to centre casing over a well prior to release and hanging within the well.