Ice-resistant offshore platform for seismic regions
(57) Abstract:The invention relates to the construction of offshore marine structures designed for drilling and/or production of oil or gas in seismic areas with ice period. Ice-resistant platform has a floating hull with ballast tanks, equipped at the bottom of a vertically oriented farm, and the mooring system with inclined anchor links, located in the star order hawse and bottom of pile anchors. In addition, it is equipped with extra suspension system with inclined links that through the hawse holes in the lower part of the farm is based floating body, with angled connection of the suspension is stretched vertically in the direction opposite to the direction of tension of the mooring system with inclined anchor links and rely on the Central beams piles piles with elevation above the bottom of the sea more than the distance from the bottom of the sea the hawse suspension with inclined links on the bottom of the farm. The buoyancy of the hull of the platform is made less than the sum of its weight and the vertical projection downward force from the mooring system with inclined anchor links. The proposed design allows you to provide simultaneously against the practical progress of the seabed and Umilenie movements from the effects of rough seas. 1 Il. The invention relates to the field of construction of offshore marine structures designed for drilling and/or production of oil or gas from offshore fields in seismic areas of the ice age.Known for numerous marine structures (see, for example, D. A. Mirzoev. Oil and gas resistant construction of the shallow shelf. - M.: VNIIEM, 1992, page 15, 26 or So Dawson. Design of offshore structures. Leningrad: Sudostroenie, 1986), installed on the bottom of the sea: the gravitational - presses to the ground due to the ballast, pile on pile Foundation and pile-gravity. Solid construction (steel or concrete), made of slabs, forming a tight loop, reliably withstand the ice fields, giving them the power to the ground, but at a depth of more than 60-80 m platform of this type become cumbersome and bulky, and their cost increases in cubic degree from the depths of the sea. In addition, for gravity platforms in seismic areas need a lot of ballast to ensure stability, along with the growing pressure from the ice loads can lead to invalid razrushauschiesa.Much less sensitive to the seismic impact of the platform on a floating base for tension ties (foreign terminology TLP), anchored gravitational or pile anchors (see, for example, Recommended Practice for Planning, Designing and Constructing Tension Leg Platforms, API RP 2T, American Petroleum Institute, 1997, S. 3, 12-28, 55). These platforms are used mainly for medium and large depths of the sea, and classifying their characteristic is that anchor ties are strained by excess buoyancy of the hull. The specified type platforms feel the seismic shift of the ground only through the bottom, usually in the form of piles or beams piles, anchors, support which is easy to prevent.Closest to the proposed decision of a kind specified type platforms platform type Spar (see J. E. Halkyard, J. Murray "Spar As a Production Platform in the Arctic Environment", Proceedings of the Third International conference "Development of the Arctic seas of Russia" RAO'97, S. Petersburg, 1997, S. 17-22, 25, 31, 34), "truss" option which is taken as a prototype. Floating anchored platform - prototype (see Fig. 2), has to support the upper structure 1 floating body 2 in the form of a vertically extended column with ballast tanks and attached to the chassis bottom vertical (if necessary). Farm 3 ballast ensures the stability of the platform as floating structures in operational working position of the platform. The mooring system of this platform with inclined anchor links 5, located in the star order, hawse holes 6 and the bottom of pile anchors 7 holds the platform above the wells so that movement of the floating body 2 from the effects of external disturbances did not exceed the allowable use of drilling and production risers 8. Such platforms are installed at relatively large depths (200 m and more), along with the seismic disturbance and can easily withstand the effects of rough seas, having a small amplitude of pitching due to the substantial differences in the period of natural oscillations (as inverse pendulum on strained ties) and periods of the waves.However, this type of structures is poorly resists the global ice load, because the drifting ice its pressure displaces the floating body structure in a horizontal direction to an invalid value, nakrekal and protoplanet it due to the strong tension ties located from the application of the ice load, and the small area of the waterline. To prevent excessive source of Finance for load i.e. the "vicious circle" in the design.The present invention is to solve the problem of providing ledostojkoj structures, i.e., preservation of body movements of the platform in a valid (riser) limits when exposed to ice, preserving, at the same time, sufficient resistance to seismic and wave impact.To achieve the desired results support the base platform is made, as in the prototype, of the vertically stacked: a buoyant hull (for example, a vertical waterproof columns) and a vertically oriented farm abuts the bottom end farm in additional mooring system - a suspension system, while the lower end of the farm does not reach the bottom of the sea to a distance defined by the mounting technology, but not less than the maximum in the area of sea-level change (caused, for example, the tide-the tide and/or storm surge). Thus, the platform has two mooring system. The upper mooring system (prototype) has the hawse holes, placed on the floating body or the upper part of the farm, and inclined (to oppose the ice load) tension connection, fixed bottom anchors, and additional the e farm and inclined (oriented vertically opposite relations top systems that the total force is directed upwards) short communications, located in the horizontal projection of the stellar image is fixed on the pile anchors. Pile anchors represent clusters (fascicles) of piles fastened together, the Central of which rises above the bottom to the height, the greater the distance the hawse on the farm from the bottom of the sea. The total buoyancy of the column and farms with less weight structures (together with superstructure) in the amount of vertical projection forces of the tension ties the top of the mooring system so that part of the weight of the structure was perceived lower suspension system. The resulting so negative buoyancy of the platform (the value of which must be greater than the amplitude of the vertical lifting force from the maximum wave), is provided by a corresponding limitation of the floating volume of the body and is additionally regulated by the admission of water into the ballast tanks.Due to the presence of such a design is achieved, firstly, sufficient ledostojkoj platform due to the fact that the floating bearing housing through the farm to the additional lower suspension prevents peoplenew and the inclination of the support base and, thus, the conditions DOPOMOGA base and overturning moment. Secondly, remains characteristic for floating structures low sensitivity to seismic shock through the free bearing of the lower end of the farm. Third, increases resistance to wave loads as by maintaining a small area of the waterline of the hull, and by the possible regulation of the period of oscillations of the structure by choosing the optimal tension of the upper links with the transfer of part of the load on the lower link.The proposed structure is illustrated in the drawing.The drawing shows a General view of the platform in operational working position. The platform consists of the upper structure 1 (modules for various purposes, rig etc), the support base including a floating body 2 with ballast tanks 3 and supporting farm 4, and two mooring systems. Top (traditional) system includes hawse 5, the floating body 2, the anchor connection 6 and bottom anchors 7 (preferably pile type). The lower the mooring system - a suspension system includes hawse holes 8 on the lower end of the farm 4, the beams piles 9 and the tension connection 10. Both the upper and lower links can be composed of steel beams or synthetic ropes, or chains, or cords t the sediment structures may be regulated due to ballast tanks 3 floating body 2 when you install the platform and in the process of operation depending on the load, environmental conditions, season, sea level to optimize counter external loads.The resistance of the platform with respect to external loads and its stability is ensured in the following way. When earthquakes shake the ground, manifested in the form of vertical and horizontal accelerations and motions. When this occurs predominantly horizontal displacement of pile anchors 7 and 9, leading thanks to the free suspension farm 4 and the damping effect relationships 6 and 10 only to a small safe (for the upper structure 1 and equipment ties with wells) the concussion of the housing 2. All vertical efforts from the earthquake and from the sea or periodic fluctuations in the level of amortized vertical compliance of the links 6 and 10 and the freedom of the suspension 10. In the case of a violent storm arising wave forces and moments do not lead to large amplitude oscillations of the floating body 2 due to the selection of such tensions links 6 and 10, which provide the periods of oscillations of the structure, far from the resonant periods of rough seas. And, finally, in the event of exposure drifting ice fields the existence of two systems mooring allows komiya and heavy loads on the bottom of the sea. A characteristic property of the proposed design (absent in the prototype) is that when exposed to ice (approximately at the level of the waterline) the top of the mooring system to counter panning and tilting is provided by the maintenance side of the lower suspension system that prevents peoplenew the substructure.The reaction of plants to the load may be regulated due to the optimal (for the season) the ratio between the buoyancy body 2 and the tension of the top 6 and the bottom 10 ties. So, for example, to better address the ice load tension ties should be strengthened to increase the rigidity of the system, and during the summer ice-free period, the tension must be, on the contrary, weakened, which will increase the period of your own pitching structures and, consequently, to avoid resonant vibrations in the band main periods of rough seas. Regulation of buoyancy of the hull is made by appointment or removal of ballast water from the ballast tanks 3.Thus, the proposed design allows you to achieve a new result, providing (previously unattainable) to execute simultaneously four qualities necessary for obespechenie fixing structure as in the top, and in the lower part (the two systems, mooring and suspension), 2) prevent unacceptable impacts on the ground - due to the partial compensation of the weight of the structure and vertical loads buoyancy of the case support base 3) repayment of accelerations from seismic movements of the sea floor due to the rolling of elastic knot fastening anchor farm, 4) Umilenie movements from the effects of rough seas due to the adjustable buoyancy of the hull and pull the anchor links of the upper and lower systems. Ice-resistant offshore platform for seismic regions, containing the supporting base in the form of a buoyant hull with ballast tanks, equipped at the bottom of a vertically oriented farm, and the mooring system with inclined anchor links, located in the star order, hawse and bottom of pile anchors, characterized in that the ice-resistant platform equipped with an additional mooring system in the form of a suspension with inclined links that through the hawse holes in the lower part of the farm is based floating body, with angled connection of the suspension is stretched vertically in the direction opposite to the direction of tension of the mooring system with inclined anchor links and rely on the Veski with inclined links on the bottom of the farm, thus the buoyancy of the hull is less than the sum of its weight and the vertical projection downward force from the mooring system with inclined anchor links.
FIELD: hydraulic engineering, particularly building bases and foundations, namely bridge piers, in water.
SUBSTANCE: method involves monitoring water obstacle in support building place, including investigating water parameters, recording water level in the course of year, determining floor shape, investigating floor ground, influence of outer disturbing forces and calculating weight and dimensions of support foundation case on the base of above parameters; producing hollow case with several cavities; moving case to installation place; submerging case in water; pacing thereof on floor; fixing case by piles and smoothing floor. Case submerging and placing operations are performed simultaneously with stabilizing vertical case position by performing control and filling of corresponding cavities. Bottom smoothing process is carried out by forcing artificial material, such as concrete layers with crushed stone interlayers, under case bottom. During case placing case is secured by blades built in case bottom and by piles inserted in cavities. Correspondence between case weight, number of blades, head resistance and side friction thereof for particular ground is determined to provide case stability on ground. Upper edge of submerged case is located above maximum possible water wave height. Rock fill is formed around underwater case part.
EFFECT: reduced time of support erection, increased reliability and stability, safety and service life, reduced labor inputs, possibility to erect supports in Arctic basin.
3 cl 1 ex
FIELD: stationary sea oil platforms.
SUBSTANCE: block has underwater support, made in form of two-level bench, formed by vertical beam cases and horizontal links, and also has support columns, connected to support. Horizontal links of bench are made in form of floating tanks, while links, placed along perimeter of lower level of bench, are separated by water-impenetrable walls on sections, provided with ballasting means. Method for mounting support block at the bottom of continental shelf includes transporting, ballasting of floating tanks and fixing support block at the bottom of water body. Support block is transported into wells drilling zone in planned position, sections of floating tanks are ballasted until lower level of support lowers into bottom of water body for 0.3-0.7 of its height, different and slants are evened and holding beams are inserted into cases of support with their following forcing into hard bottom portion and fixing in cases. Ballasting of sections of floating tanks and forcing of holding beams can be performed in pairs in diagonal planes relatively to center of lower level of support.
EFFECT: simplified assemblage, higher reliability.
2 cl, 12 dwg
FIELD: hydraulic engineering, particularly for forming temporary structures for enclosing closed in plane water area bottom part and space above the bottom part through the full water thickness.
SUBSTANCE: method of shallow tunnel construction involves forming structure enclosing closed in plane bottom part; removing water from the structure; performing works in dry structure and demounting above structure. Method of enclosing structure forming involves producing bottomless hydraulic enclosure with controlled floatability; transporting and moving thereof to tunnel path; immersing the enclosure in water up to reaching water area bottom by reducing floatability thereof and fixing enclosure with fastening means and anchor system; leveling upper enclosure part with horizon line and arranging cranage and platforms for building material storage on upper enclosure part; erecting cutoff walls inside space defined by enclosure; removing water from the enclosure; developing bottom ground by trench digging; constructing pile tunnel base; building foundation grill on pile tunnel base; locating composite or precast reinforced concrete tunnel sections on foundation grill; recovering initial floatability of the enclosure. Enclosure structure has movable fastening means formed as blades along vertical walls thereof.
EFFECT: increased tunnel reliability, reduced time of erection thereof.
4 cl, 4 dwg
FIELD: production of ice.
SUBSTANCE: method comprises producing a hollow near the ship's side, delivering air under the ice cover, the air volume does not exceeding the volume of the space defined by ice covering from the top, water from the bottom, and ice walls from the sides over the contour of the future hollow. The walls are frozen from top to bottom by means of direct nonseparable heat exchangers mounted in advance into the covering immediately behind the contour up to the bottom of the future hollow. The delivery stops and the bottom of the future hollow is frozen with the use of L-shaped nonseparable heat exchangers set into the covering simultaneously with the direct heat exchangers. As a result, a closed space is defined, which is stripped, and ice blocks are removed.
EFFECT: enhanced efficiency.
FIELD: hydraulic engineering, particularly underwater structures adapted for oil and gas well operation, preferably on shallow continental shelf having bottom covered with thick silt layer and in ice-covered period.
SUBSTANCE: platform comprises base, vertical pile holders connected with the base and positioning unit for drilling string and well-control equipment fixation. Base is formed as a structure with cavities filled with ballast. The structure is composed of hollow members and functionally divided into two areas. Positioning unit is arranged in the first area, another area including catching opening. Platform is additionally provided with removable mounting frame with production equipment installed on the frame. Arranged in lower frame part are inclined guiding means to provide access into catching opening during mounting frame connection with support platform base in underwater position.
EFFECT: reduced labor inputs for production equipment mounting and maintenance, increased reliability.
FIELD: offshore oil-field hydraulic structures, namely for building fixed platforms.
SUBSTANCE: support substructure comprises three-dimensional latticed structure having prismatic shape and composed of tubular members. The structure has vertical panels with posts, cross-pieces, struts and horizontal diaphragms connected one to another. Horizontal diaphragms have guiding nets for marine risers. The structure is secured to ground by main piles arranged in vertical posts and by foundation having additional piles, which is rigidly connected to tubular members of side edges of above structure. The structure is provided with ice-protection means formed as two truncated prisms of sheet steel and having beveled side ribs rigidly connected one to another by major bases. Marine risers are arranged inside prisms. Each prism of ice-protection means is rigidly connected with tubular members of corresponding diaphragms of three-dimensional latticed structure.
EFFECT: increased resistance to wave, seismic and ice loads, improved manufacturability and, as a result, reduced cost of permanent offshore structure building.
3 cl, 2 dwg
FIELD: offshore oil-field hydraulic structures, namely for building fixed platforms.
SUBSTANCE: method for forming support substructure by welding large blocks involves producing and serially connecting precast members to create flat units, namely panels and diaphragms; connecting flat units by tubular inserts and tubular links to create three-dimensional latticed structure. All operations are divided into four stages in accordance with technological order. The first stage includes forming tubular links and tubular inserts, pile sections and marine riser sections. The second stage includes assemblage of flat panels and diaphragms in horizontal position on corresponding mats. The third and the forth stages include simultaneous installation of flat panels and diaphragms and rigid connection thereof.
EFFECT: reduced labor inputs, time and cost for assembly work performing due to elimination of complicated tubular joints used as assembly units.
3 cl, 7 dwg
FIELD: ground hydraulic structure erection, particularly to decontaminate silt or bottom sediments in water bodies.
SUBSTANCE: method involves building protective dam along perimeter of silt and/or bottom sediment area to be protected; laying waterproofing layer along inner dam perimeter, wherein waterproofing layer height is 2 times as much as silt and/or bottom sediment layer; forming artificial ground massif of watertight ecologically friendly natural ground in water area inside the dam, wherein artificial ground massif thickness is equal to at least three thicknesses of silt and/or bottom sediment layer; forming above-water relief area having 2.5 m height over water surface; forming surface flow discharge system and planting greenery in artificial ground massif.
EFFECT: increased reliability, reduced contamination concentration, prevention of hazardous substances ingress in ambient space and improved ecological safety.
2 cl, 1 dwg
FIELD: marine hydraulic structures, particularly fixed marine oil and gas production platforms.
SUBSTANCE: method for pile installation with the use of handling machine involves driving each pile in conical hole made in guiding means fixedly secured to marine platform base; installing pile and guiding means in coaxial position by guiding device having body installed on guiding members of the base so that the body may be displaced and fixed in predetermined position; lowering pile to working position; installing guiding device above water level on guiding members of platform base in predetermined position, wherein the guiding device is made as cylindrical body part and cylindrical part of guiding member secured one to another and having crossing axes so that cylindrical part of guiding means and cylindrical part of guiding member of guiding device are brought into coaxial state by corresponding linear and angular guiding member displacement; securing guiding device body with guiding members of platform base.
EFFECT: extended technological capabilities and simplified method of pile installation in working position.
5 cl, 4 dwg
FIELD: marine oil production hydraulic structure building, particularly marine platform assemblage.
SUBSTANCE: method involves forming assembly units, namely support unit, load-bearing deck and block units of upper structure, at subassembly site; docking floating vehicle to subassembly site; serially installing assembling units on stockpile carts; moving assembly units from subassembly site to floating vehicle with the use of above stockpile carts; transporting thereof to assemblage site and performing successive mounting thereof with the use of crane-and-mounting ships. The successive mounting operation involves installing support unit on previously prepared ground; installing piles in corresponding bell-shaped guiders of the support unit; driving the piles and cementing thereof to create pile foundation; arranging load-bearing deck on struts and installation guiding bars having different heights and previously formed on support unit, wherein the load-bearing deck has seats for struts and bars receiving and connection thereof is carried out by successive alignment of above bars and seats.
EFFECT: increased efficiency of building equipment and floating vehicle usage; reduced building time, decreased number of operations to be performed at sea, reduced labor inputs and decreased costs of marine fixed platform building.
7 cl, 17 dwg