The structure of the unmanned platform in Danish STAR system consists of a central column joined by a pulled out tripod of downward pipes forming the angle of 18 degrees to vertical line. The sloping pipes in the tripod form also the stiffening of the central column and a guide for piles angularly driven into the sea bed. In the central column there are passages with guiding sockets for production risers. Deck modules are situated in the upper part of the central column.

The foundation of the unmanned platform according to the Danish system is based on the principle that the basic construction, i. e the central column with the tripod, is barged to the cantilever jack-up. A protractile mounting crane lifts the basic platform structure over the barge which is then pulled away. The lifted unmanned platform structure is lowered onto the sea bed and then piles are driven into the pipe columns at an obtuse angle and deck modules are placed on the upper part of the central column.

The essence of the present invention in the field of construction is an unmanned platform, which has a bottom plate with the main carrying pillars braced together by clippers through segment wedge inserts.

Above the sea level there is a deck module consisting of a mooring platform, stay-ropes maintenance deck, nose deck and upper deck with crane. In the lower part the carrying pillars, dependently of conditions, form a combination with the stiffening pillars by filling the space between them with cement inject and stay-ropes moored by mooring plates. Bracing clippers of the main carrying pillars have passages for the pillars and the production risers. At the end of the passages there are sockets mating with upper and lower segment wedge inserts.

The essence of the present invention in the field of unmanned platform foundation, is based on the principe that the bottom plate is placed on the sea bed, clippers are underslung in the platform operating space and the main carrying pillars connected by connectors are introduced, guided to the bottom plate and lowered down to the sea bed. Clippers with wedge segments are spaced and wedged on the main carrying pillars, which is followed by the placement of the deck module elements. After wedging clippers by wedge segments on the main carrying pillars, stiffening pillars are inserted, the pillars are placed on the sea bed and spaces between them are filled by cement inject. Additionally stay-ropes are established, tightened with hydraulic cylinders and locked by chain stoppers on the stay-ropes maintenance deck.

According to the present invention the unmanned platform for the recovery of minerals from the sea bed, especially oil and natural gas, allows surface heading of four exploratory holes and one hole for water compression. Distribution of a couple of unmanned platforms in the radius of 4000 m from the production centre on the main platform is enough for the effective deposit exploitation. The construction affords possibilities for the deposit drilling in automatic mode without working personnel participation during platform exploitation. Scheduled maintenance and repairs, made by a maintenance team transported by sea, are completed during the period of up to 12 hours. Control is provided by high frequency radiolink from the main platform. Environment protection against pollution by crude oil spill is provided by leakproof head deck construction with sump tank. The platform has inflatable life rafts, evacuation equipment, life buoys, thermal suits. Cranes, designed in the form of gantry, assure vertical transportation and possibility to measure bottom-hole pressures and easy work like stamping, templeting. The platform and its foundation on the sea bed are adapted for the Baltic Sea conditions and after the exploitation has been completed it can be disassembled by ordinary equipment. without the necessity to use specialised equipment and induced expenses.

The object of the present invention is presented on the drawing, where fig. 1 presents schematic overview of the unmanned platform, founded and anchored in the sea bed, fig. 2 presents end view of the clipper, fig. 3 top view of the clipper, fig. 4 longitudinal section of the lower part of the main pillar with stiffening pillars, fig. 5 cross-section of the main pillar, fig. 6 cross-section of the main pillar with stiffening pillar, fig. 7 cross-section of the main pillar with the stiffening pillars, fig. 8 cross-section of the stiffening pillars.

Object of the present invention in the field of construction in the effect example consist of the bottom plate 8, with four main support pillars 15 joined by clippers 6 through lower 13 and upper 14 wedging inserts. It has the deck module 23 over the sea level, which consist of mooring stage 5, stay-ropes deck 4, heading deck 3 and upper deck 2 with crane 1 in form of gantry. Main support pillars 15 in the lower part form a complex with stiffening pillars 11 and 12 by filling the space between them by cement inject 16. The unmanned platform has stay-ropes 7 anchored by anchoring plates 9, fixed to the sea bed by pillars 10. Distributed on the main support columns 15, clippers 6, have connected through construction elements 19, main support pillars 15 passages 18 and production risers 20 passages 17, which are ended by seats 21 and 22 co-operating with upper 14 and lower 13 segmented wedging inserts.

Object of the present invention in the field of foundation of the unmanned platform, in the effect example is based on the bottom plate 8 lying on the sea bed. Clippers 6 are underslinged in the operating field of the drilling platform and into its passages 18 main support pillars 15 are introduced and joined by connectors which are next guided onto holes in the submerged bottom plate 8 and lowered onto the sea bed. On the length between sea bed and sea level of main support pillars 15, clippers 6 are placed and wedged by lower 13 and upper 14 wedge segment. After wedging stiffening pillars 11 and then the stiffening pillar 12 are introduced into the main support pillars 15 and lowered down onto the sea bed and the space between them is filled by cement inject 16. On the main support pillars 15, in overwater part, parts of deck module are placed. Next stay ropes 7 are established and then tightened by hydraulic cylinders and fixed by chain stoppers on the stay ropes deck 4.