Abstract: A system for running riser pipes from a floating vessel to each of a plurality of conductors set in the sea floor in a circular pattern. A vertically mooring guidance riser is first connected between the center of the pattern and the floating vessel. A permanent riser pipe is guided down to one of the conductors by use of a guide frame positioned on the guidance riser. When all of the permanent riser pipes are run, the guidance riser may be removed. Special running tools and guide frames are described.

Abstract: A sea floor template with vertical well guides or slots is lowered to the sea floor. Guide rails, such as a railroad track, are supported on top of the frame of the template in a path which extends along each well slot. A drilling guidance carousel is lowered to the template. Rollers on the drilling guidance carousel engage guide rails so that the carousel can be moved to each template well slot. Guidelines extend from the drilling guidance carousel to a floating drilling vessel for guiding drilling equipment from the vessels down through the template well slot which is aligned with the carousel well slot. Preferably, the template well slots are arranged in a circle at each corner of a rectangular sea floor template. The guide rails are arranged concentrically with the central axis of the circle of template well slots. Locking means are provided to hold the carousel drilling frame well slot aligned with any selected one of the well slots in the sea floor template.

Abstract: A latching and unlatching system for connecting a riser pipe to the casing in a subsea well. A split-circumferential ring fits into mating grooves in the male end of the casing and the female end of the riser. A releasing tool runs on a drill pipe suspended within the riser pipe and has a number of radially extendible pistons actuated by hydraulic pressure through the drill pipe to expand the split ring out of the casing groove to the grooved recess of the riser pipe. This releases the riser pipe from connection with the casing so it can then be raised.