Patent GB-756826-A (GB)
Title: Deepwater oil drilling and storage craft
IPC: E21B15/02
Filed: 1954-11-09
Abstract: 756,826. Boring earth and rock; landing- stages. NELSON, F. N. Nov. 9, 1954, No. 32367/54. Classes 68(2) and 85 Oil drilling gear 52 is mounted on the top 43 of a column 25, 60, 42 which rests upon and is secured to the sea-bed, and a floating breakwater and storage vessel 2 rises and falls and pivots upon the part 42 of the column. The vessel 2 has a bow which faces the weather, and shoulders behind outwardly curved sides 4a to form shelters for small craft. The stern of the vessel 2 is flared outwardly at 5a and a longitudinal gap 10 extends to the pivot point which is in the bows. The part 42 of the column is retained in the pivoting position by a dry-dock barge 12 which is floated into the gap 10 and has sliding connection with key ways on the sides of the gap. In use, the parts 25, 42 of the column. fitting one within the other as shown in Fig. 4, are retained by their own buoy-  a ncy in the well formed by opposed semicylindrical plates 23, 24 on the vessel 2 and the barge 12 respectively, and are moved with the vessel 2 to the desired location. Alternatively, the parts 25, 42 are floated, by opening the end gates 14 of the dry-dock barge 12, into the barge and transported to the location. The barge is then partly withdrawn from the gap 10 to permit the plate 24 to be removed and the end gates 14a to be opened. The parts 25, 42 are then floated out of the barge against the plate 23, and the plate 24 is re-secured to the barge which is moved fully into the gap 10 to secure the part 42 pivotally. The barge is then clamped to the vessel 2. The intermediate section of the column is built upon the base part 25, and consists of metal tubes 60 screwed into one another as the base 25 is lowered, by controlled flooding, from the position shown in Fig. 4. The tubes 60 pass through tubes 62, welded in the base 25, and project downwardly therefrom to act as piles. The lengths of tubes 60 are added until the base 25 rests upon the sea-bed, and as the base 25 sinks an axially disposed shaft 65 is also built up together with an adjacent duct 70 in two halves, rigidly joined with the shaft 65 as shown in Fig. 10. The duct 70 serves for the operation of elevators and as ventilation, escape and access trunks to the interior of the base 25. The tubes 60, 65 are cross braced at 66 and guys 95 steady the 'pivot structure. Piles 36 peripherally arranged around the base 25 are clamped thereto by tightening straps 35 from within the base. In shallow water, the intermediate section of the column may be dispensed with, the base 25 being simply lowered within the part 42 to rest on the sea-bed. The base 25 may be lengthened to provide greater internal working space and limits of movement within the part 42. Alternatively, the base 25 and the part 42 may be combined in one integral unit. Drilling is effected through the bottom of the base 25, tubes 100, Fig. 12, being set at the required angle for this purpose. The tubes are fitted with valves 101, 102 for the passage of a drill pipe 103 and/or casing and to permit change in the angular direction of the drill pile. The vessel 2 is propelled by swivelling units 110. A wave screen 96, on the fore-deck, and divers' hatches 115 are provided. Small craft can shelterin the harbour 8.