GB772082A - Improvements in or relating to methods of constructing a foundation for an underwater drilling rig and foundation units for use in carrying out this method - Google Patents

Abstract

772,082. Subaqueous buildings. NAAMLOOZE VENNOOTSCHAP DE BATAAFSCHE PETROLEUM MAATSCHAPPIJ. Sept. 29, 1955 [Oct. 1, 1954], No. 27755/55. Class 68 (2). A foundation for an underwater drilling rig is constructed by positioning over the site, a unit consisting of a number of watertight tanks 13 in buoyant condition, the tanks being hinged together at their ends to form a closed loop, sinking the tanks by flooding, and filling the space enclosed by the unit with solid material 16. A submersible drilling barge 11 is sunk upon the solid material and may be secured by piles 43 driven through the barge into the sea bed. The tanks are each provided with one or two air valves 41, the valves of adjacent tanks being connected by flexible conduit 42 so that, air which is pumped into the system enters all the tanks and expels the water to restore buoyancy to the assembly. The tanks are provided also one or more flooding valves 35 which are by handwheels 37 in recesses 38 which accommodate the valves 41. The valves 35 may likewise be accommodated in the recesses 38 or in other recesses. The tanks 13 are connected by pins 28 in hinge lugs 26, 27, or piles 31 may act as pivot pins, the piles being driven through the lugs 26, 27 into the sea-bed, or piles 34 may be driven through guides 33 in or on the tanks. A pin hole 32 in each pile 31 enables the pile to be supported in a raised position whilst the unit is being floated into position, a pin inserted in the hole resting upon the top of the tank. After drilling has been completed, the piles 31, 34, and hinge pin are removed, and the tanks are floated and towed away, the solid material then sliding to its angle of repose at the edges.