US20040052586A1 - Offshore platform with vertically-restrained buoy and well deck - Google Patents

Offshore platform with vertically-restrained buoy and well deck Download PDF

Info

Publication number
US20040052586A1
US20040052586A1 US10/616,399 US61639903A US2004052586A1 US 20040052586 A1 US20040052586 A1 US 20040052586A1 US 61639903 A US61639903 A US 61639903A US 2004052586 A1 US2004052586 A1 US 2004052586A1
Authority
US
United States
Prior art keywords
platform
buoyancy apparatus
risers
deck
tendon
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US10/616,399
Other languages
English (en)
Inventor
Edward Horton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DeepWater Technologies Inc
Original Assignee
DeepWater Technologies Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US10/213,967 external-priority patent/US6854933B2/en
Application filed by DeepWater Technologies Inc filed Critical DeepWater Technologies Inc
Priority to US10/616,399 priority Critical patent/US20040052586A1/en
Priority to AU2003257153A priority patent/AU2003257153A1/en
Priority to BRPI0313324-9B1A priority patent/BR0313324B1/pt
Priority to EP03784895A priority patent/EP1540127B1/en
Priority to DK03784895T priority patent/DK1540127T3/da
Priority to PCT/US2003/024320 priority patent/WO2004015239A2/en
Priority to OA1200500034A priority patent/OA12898A/en
Assigned to DEEPWATER TECHNOLOGIES, INC. reassignment DEEPWATER TECHNOLOGIES, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HORTON III., EDWARD E.
Publication of US20040052586A1 publication Critical patent/US20040052586A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
    • B63B21/50—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers
    • B63B21/502—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers by means of tension legs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
    • B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
    • B63B35/4406—Articulated towers, i.e. substantially floating structures comprising a slender tower-like hull anchored relative to the marine bed by means of a single articulation, e.g. using an articulated bearing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
    • B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
    • B63B35/4413—Floating drilling platforms, e.g. carrying water-oil separating devices
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/01—Risers
    • E21B17/012—Risers with buoyancy elements
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/20—Flexible or articulated drilling pipes, e.g. flexible or articulated rods, pipes or cables
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B19/00—Handling rods, casings, tubes or the like outside the borehole, e.g. in the derrick; Apparatus for feeding the rods or cables
    • E21B19/002—Handling rods, casings, tubes or the like outside the borehole, e.g. in the derrick; Apparatus for feeding the rods or cables specially adapted for underwater drilling
    • E21B19/004—Handling rods, casings, tubes or the like outside the borehole, e.g. in the derrick; Apparatus for feeding the rods or cables specially adapted for underwater drilling supporting a riser from a drilling or production platform
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
    • B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
    • B63B2035/442—Spar-type semi-submersible structures, i.e. shaped as single slender, e.g. substantially cylindrical or trussed vertical bodies

Definitions

  • the present invention relates to offshore platforms, and specifically to offshore platforms designed for dry tree applications. More particularly, the present invention relates to a new production and/or drilling riser system used in deep draft dry tree offshore platforms.
  • Conventional dry tree offshore platforms are low heave floating platforms, such as spars, TLPs (Tension Leg Platforms), and deep draft semi-submersible platforms. These platforms are able to support a plurality of vertical production and/or drilling risers. These platforms can comprise a well deck, where the surface trees (arranged on top of the riser) will be located, and a production deck where the petroleum product (e.g., crude oil or natural gas) will be distributed to a processing facility to separate water, oil and gas. These two decks are part of the hull of the offshore platform.
  • vertical risers running from the well head to the well deck are supported by a tensioning apparatus. These vertical risers are called Top Tensioned Risers (TTRs).
  • TTRs Top Tensioned Risers
  • FIGS. 10A and 10B There are two conventional designs for applying tension to the TTRs respectively illustrated in FIGS. 10A and 10B.
  • the first design shown in FIG. 10A, uses one or more passive buoyancy cans 10 to independently support a riser 12 .
  • FIG. 10A shows a top tensioned riser arrangement 12 with buoyancy cans 10 , of a type that is mainly employed on spar-type floating platforms, as disclosed and claimed in U.S. Pat. No. 4,701,321—Horton.
  • Each riser 10 extends vertically from a wellhead 14 on the seabed to the top of a well deck 18 of the offshore platform. The riser passes from the wellhead 14 through a keel joint 20 into the center well 22 of the buoyancy cans 10 .
  • the riser 12 passes through a stem pipe 24 that passes through the center of the buoyancy cans 10 .
  • the stem pipe 24 extends above the buoyancy cans 10 and supports the well deck 18 to which the riser 12 and a surface tree 26 are attached.
  • the buoyancy cans 10 and the stem pipe 24 are guided at several locations in the center well 22 by a plurality of riser guides 28 . Because the risers 12 are independently supported by the buoyancy cans 10 (relative to the hull), the hull is able to move up and down relative to the risers 12 , and thus the risers 12 are isolated from the heave motions of the offshore platform.
  • the buoyancy cans 10 need to provide enough buoyancy to support the required top tension in the risers 12 , as well as the combined weight of the cans 10 , the stem pipe 24 , and the surface tree 26 . With increased depth, the buoyancy required to support the riser system will correspondingly increase, requiring larger buoyancy cans 10 . Consequently, the size of the center well 22 will increase proportionately. Designing and manufacturing individual buoyancy cans 10 for each riser 12 is also costly.
  • the second conventional design uses an active hydraulic tensioning mechanism to independently support the risers 12 .
  • Each riser 12 extends vertically from the wellhead 14 to the production deck 32 of the offshore platform.
  • the riser 12 is supported by active hydraulic cylinders 30 connected to the well deck 18 of,the offshore platform, allowing the hull to move up and down relative to the risers 12 and thus partially isolating the risers 12 from the heave motions of the hull.
  • a surface tree 26 is connected to the top of the riser 12 .
  • the required tension and stroke increase in magnitude, the size of the hydraulic cylinders 30 correspondingly increases and may become prohibitively expensive. Furthermore, the loads have to be supported by the offshore platform.
  • the tensioning device allows the isolation of the risers from the heave motions of the offshore platform.
  • the well deck as well as the production deck will move up and down relative to the surface trees. Consequently, in order to absorb these motions, high pressure flexible jumpers 34 (FIG. 10A and 10B) are required to connect each surface tree in the well deck area to a manifold (not shown) on the production deck 32 which carries the liquid petroleum product to a processing facility to separate water, oil and gas.
  • the high pressure flexible jumpers 32 are expensive compared to rigid piping and can lead to design problems, especially in high pressure/high temperature environments.
  • the tendons will have to be designed to limit the horizontal motion of the small well deck TLP.
  • These concepts will require at least four tendons arranged on the outer periphery of the small well deck TLP, and risers will be arranged in between these tendons.
  • risers will be arranged in between these tendons.
  • one must solve the problem of collision between the risers themselves, and between the risers and tendons, by providing sufficient spacing between the several risers, and between the risers and the tendons. This leads either to a large buoy to accommodate several risers, or a small number of risers supporting by the small well deck TLP.
  • high pressure jumpers are still required to connect each surface tree to the manifold of the production deck.
  • the present invention addresses the problems just described and proposes a new passive tensioning system for top-tensioned risers in dry tree floating platforms, most advantageously spars and deep draft semi-submersible platforms.
  • the present invention provides for tensioning all the risers with a single buoyancy apparatus, which can be a large single buoyancy can or a multi cellular buoyancy apparatus.
  • a “deep draft” semi-submersible floating platform is defined as a low-heave platform having a draft of at least about 150 ft. (45 m), and able to guide or receive top-tensioned risers.
  • a first unique feature of the present invention is that, contrary to prior art (where the well deck is supported by the offshore platform), the single buoyancy apparatus includes the well deck arranged on its top surface. Since the risers are connected to the same buoyancy apparatus, they act as a single riser system, and surface trees on top of the risers can be rigidly attached on top of the buoyancy apparatus. Consequently, all the surface trees can be connected to a manifold on the w ell deck (not the production deck) with rigid piping.
  • the crude oil will be choked down in the entry of the manifold, and, contrary to the prior art, one or just a few low pressure flexible jumper(s) (or rigid articulated arms) can be used to carry the liquid petroleum product (e.g., crude oil) to the processing equipment on the production deck.
  • the use of a small number (as low as one) of low pressure flexible jumpers or articulated rigid arms will considerably reduce the cost of the riser system as well as the required deck room.
  • a second unique feature is the use of concentric tendons attached at the well deck (or top of the single buoyancy apparatus) on the center line of the single buoyancy apparatus. When one tendon is used, it will be connected to the well deck on the centerline of the buoyancy apparatus. When more tendons are used, their centroid will be close to the vertical centerline of the apparatus.
  • the use of central tendons limits the over-stressing of the risers and the requirement for a reinforced wellhead foundation, as tension loads will be withstood principally by the tendons themselves and their foundation.
  • the use of concentric tendons will provide much flexibility in the design of the tendons to achieve the required dynamic behavior.
  • Three factors are important in the design of the tendons: (1) The tendons must be strong enough to withstand the maximum static and dynamic loads imparted to them by the spar. (2) The buoyancy apparatus must impart sufficient upward tension at the top of the tendons to prevent them from going slack at the base. (3) The tendons must have sufficient axial stiffness to keep the riser system from going into resonance due to cyclic wave forces.
  • the present invention avoids the need to have several tendons arranged in the outer periphery of the buoy, and thus reduces the cost of the riser system and simplifies the resolution of the problems of riser and riser/tendon collisions.
  • FIG. 1 shows a cross-sectional view of one exemplary embodiment of a floating platform in which the risers are supported by a single buoyancy system and are coupled to a central tendon assembly for restraining the vertical motion of a single buoyancy system;
  • FIG. 2 shows a cross-sectional view of the floating platform in which the risers are supported by a single buoyancy system, vertically restrained by central tendons, the riser being independent from the central tendon;
  • FIG. 3 shows a cross-sectional view of the floating platform in which the risers a re supported by a single buoyancy system
  • FIG. 4 shows a cross-sectional view of the floating platform in which the single buoyancy system also supports the drilling rig and its associated equipment;
  • FIG. 5 shows a top view of the well deck arrangement
  • FIG. 6A is an elevational view, partially in axial cross-section, showing one exemplary embodiment of the tendon riser arrangement
  • FIG. 6B is a cross-sectional view taken along line 6 B- 6 B of FIG. 6A;
  • FIG. 7 shows another exemplary embodiment for the single buoyancy system wherein the buoyancy system comprises a plurality of vertical tubes closely spaced and connected together through elongated vertical webs;
  • FIG. 8 shows the use of the invention in a deep draft semi-submersible platform
  • FIG. 9 shows one exemplary embodiment of the well deck arrangement on top of the buoyancy system.
  • FIGS. 10A and 10B show prior art riser systems.
  • FIG. 1 shows one exemplary embodiment of the invention used in a spar type floating platform 100 .
  • FIG. 1 shows the spar type platform 100 having a spar hull 102 defining a center well 104 .
  • a vertically restrained buoyancy apparatus 106 is guided in at least two locations (upper and lower) within the center well 104 of the spar hull 102 .
  • This specific spar type platform 100 comprises an upper hull and a lower hull.
  • the upper hull and the lower hull share the continuous hollow center well 104 , which surrounds and guides the center well buoyancy apparatus 106 .
  • the upper hull includes a cellular structure comprising several compartments 108 for buoyancy purpose (void tanks and variable ballast tanks).
  • the lower hull includes a sleeve 110 with a fixed ballast 112 near the bottom of the lower hull to lower the center of gravity and thus improve the stability of the platform 100 .
  • the spar type platform 100 supports a work platform 114 comprising a production deck 116 , compartments 118 for crew quarters and utilities, and a drilling deck 120 for drilling equipment, such as a drilling rig 122 .
  • the floating platform 100 is moored with lateral mooring lines 124 in a taut leg mooring configuration or catenary mooring configuration.
  • the lateral mooring lines 124 are designed to limit the horizontal movement of the floating platform 100 relative to seabed wellheads to specified limits to prevent the risers (described below) from being over stressed.
  • the buoyancy apparatus 106 can be a single large buoyancy can or a multi-cellular buoyancy system (described below and shown in FIG. 7).
  • the center well buoyancy apparatus 106 is itself free floating within the center well 104 . Because the spar hull 102 and the center well 104 are each free-floating, the spar hull 102 moves to accommodate the environmental forces acting on it, and thus moves with respect to the vertically restrained center well buoyancy apparatus 106 .
  • the spar hull 102 heave motion is decoupled from the center well buoyancy apparatus 106 .
  • at least first and second pluralities of guides 128 are provided in the center well 104 at selected, axially-spaced locations, and at least at upper and lower locations, to guide the buoyancy apparatus 106 within the center well 104 .
  • the buoyancy apparatus 106 and the guides 128 are in actual physical contact.
  • the guides 128 advantageously include compliant pads (such as elastomeric pads) (not shown) that are positioned to be compressed against the buoyancy apparatus 106 .
  • a unique feature of this invention is that a well deck 130 is positioned on top of the buoyancy apparatus 106 , and all the risers 126 extend from the well deck 130 to wellheads 132 on the seabed.
  • At least one central tendon assembly 134 secures the buoyancy apparatus 106 to the seabed.
  • the tendon assembly 134 is attached at its upper end to the center of the well deck 130 , and it extends down along the centerline of the buoyancy apparatus 126 to a tendon foundation in the seabed.
  • the tendon foundation is of conventional design, described more fully below, comprising a caisson pile 138 anchored in the seabed, and a connective sleeve 140 connecting the tendon assembly 134 to the caisson pile 138 .
  • the advantage of using a central tendon assembly 134 is that it can be designed (in terms of the physical characteristics of the tendons the tendon foundation) to withstand most of the tension load, thereby reducing the tension loads in the risers 126 .
  • the requirement for reinforced foundations for the wellhead 132 will be further reduced, which is particularly advantageous in ultra deep water where the tension requirement can be quite critical.
  • the tendon assembly 134 may be designed specifically as a tendon, or it may be designed as a riser that functions as a tendon with a reinforced wellhead foundation.
  • the tendon assembly 134 and a plurality of surrounding risers 126 are coupled together with a plurality of vertically-spaced riser spacers or guides 144 , only one of which is shown in the drawings.
  • the coupling of the risers 126 with the tendon assembly 134 helps prevent the risers 126 and the tendon assembly 134 from clashing or colliding with one another due to floating platform movement.
  • the upper portions of the risers 126 are uncoupled from the tendon assembly 134 within the upper portion of the center well 104 , to allow the connection of each riser 126 to a respective surface tree 170 , and the connection of tendon assembly 134 to a tendon socket or slot 146 (FIG. 5) in the well deck 130 .
  • the bottom portions of the risers 126 are uncoupled from the tendon assembly 134 to allow the connection of the risers 126 to their respective wellheads 132 and the connection of the tendon assembly to the tendon foundation.
  • FIG. 2 shows another exemplary embodiment of the invention used in a spar type floating platform 200 , which includes risers 226 that are uncoupled from a tendon assembly 234 .
  • This embodiment provides a simplified riser and tendon construction (no need of riser spacers or guides), but the risers 226 and the tendon assembly 234 will have to be sufficiently spaced and will have to be tensioned sufficiently to avoid any collision between the risers 226 themselves and between the risers 226 and the tendon assembly 234 . Accordingly, this embodiment requires a center well 204 that must be larger than that of the embodiment of FIG. 1.
  • FIG. 3 shows another exemplary embodiment of the invention used in a spar type floating platform 300 .
  • this particular embodiment there is no specific tendon used for vertically restraining the single buoyancy apparatus 306 .
  • this embodiment employs risers 326 and wellhead foundations 346 that are designed to vertically restrain the center well buoyancy apparatus 306 .
  • FIG. 4 shows another exemplary embodiment of the invention used in a spar type floating platform 400 .
  • This particular embodiment employs a center well buoyancy apparatus 406 that, in addition to a well deck 430 , supports a drilling deck 420 with a drilling rig 422 and its associated equipment (drilling and work over), while the work platform supported by the floating structure comprises a production deck 416 with compartments 418 for crew quarters and utilities.
  • the decks 416 , 420 are conventional decks used on floating structures such as spars, TLPs or deep draft semi-submersible platforms. As the buoyancy apparatus 406 is vertically restrained, the drilling and work over operations will be less weather dependant.
  • FIG. 4 In some embodiments, because there will be no relative vertical motion between the drilling riser and the drilling rig, there will be no requirement for a slip joint arranged on the drilling riser to absorb these vertical motions.
  • the embodiment of FIG. 4 employs risers 426 and tendons 442 that are coupled; however, the risers and the tendons can be uncoupled as shown in FIG. 2, or the buoyancy apparatus can be vertically restrained by the riser itself, as shown in FIG. 3.
  • the embodiment of FIG. 4 does, however, require additional buoyancy to support the extra weight of the drilling/work over equipment.
  • the tendons and/or the risers are secured to the seabed at one end (wellhead or tendon foundation), and to the well deck on the center well buoyancy apparatus at the other end.
  • FIG. 5 shows a horizontal cross sectional view of an example of a well deck assembly 500 .
  • the well deck assembly includes a well deck 130 having a tendon socket or slot 146 in its center to receive a tendon assembly 134 .
  • Around the tendon slot 146 are several riser sockets or slots 548 .
  • a drilling well or moon pool 552 On either side of the tendon riser center well 550 is a drilling well or moon pool 552 .
  • the moon pools 552 also provide space for performing drilling and work over operations or for running equipment down to the seabed.
  • the center well buoyancy apparatus 106 is guided with a plurality of guides 128 (four guides, in this example), arranged around its perimeter.
  • the number of guides 128 may be varied from as few as two to five or more, depending on the loads they are to absorb.
  • FIGS. 1 to 5 only one tendon assembly 134 attached to the well deck 130 and extending down the centerline of the buoyancy apparatus 106 is shown. However, in other embodiments, there may be more than one tendon assembly aligned and/or parallel with the vertical centerline of the buoyancy apparatus. The various other embodiments may employ multiple tendon assemblies (not illustrated), closely arranged around the central tendon assembly.
  • the tendon assembly 134 is secured to the seabed by a caisson pile 138 , which is alternatively called an anchor caisson or a suction pile.
  • the caisson pile 138 secures the tendon assembly 134 to the seabed.
  • the tendon assembly 134 may optionally be connected to the caisson pile by the tendon connection sleeve 140 , which is located in the center of the caisson pile 138 , through which the bottom end of the tendon assembly 134 is fixed to the seabed.
  • Radial plates 154 connect the tendon assembly 134 to the interior wall of the connection sleeve 140 .
  • the caisson pile 138 is pushed into the seabed by pumping water out of its interior. As water is pumped out, the ambient external water pressure pushes the caisson pile 138 down into the seabed. In other embodiments, the caisson pile 138 is pushed into the seabed by means of submersible pumps (not shown), airlifts (not shown), or any other method that may suggest itself to those of ordinary skill in the art. With the caisson pile 138 firmly anchored in the seabed, the tendon connection sleeve 140 connects the tendon assembly 134 to the caisson pile 138 , thereby securing the tendon assembly 134 to the seabed.
  • At least one of the tubular tendon elements 136 of the tendon assembly 134 is drilled into the seabed and anchored therein by cement. This increases the pullout resistance of the tendon assembly 134 .
  • the tendon connection sleeve 140 is extended out of the bottom of the caisson pile 138 , thereby providing a connector through which the tendon elements 136 are drilled and connected.
  • the tendon assembly 134 may be secured to the seabed by any other method that may suggest itself to those of ordinary skill in the art.
  • FIGS. 6A and 6B show the structural details of one exemplary embodiment of a tendon assembly 134 .
  • the tendon assembly 134 comprises multiple (at least two) concentric tubular tendon elements 136 .
  • the concentric tubular elements 136 are secured to the well deck 130 on the vertical centerline of the center well buoyancy apparatus 106 , and they extend down to an anchor assembly at the seabed, as discussed above.
  • the use of concentric tubular tendon elements 136 provides great flexibility in the design of the tendons to achieve the required dynamic behavior.
  • the tendon assemblies 134 must be strong enough to withstand the maximum static and dynamic loads imparted on them by the buoyancy apparatus 106 .
  • the buoyancy apparatus 106 must impart sufficient upward tension at the top of the tendon assemblies 134 to prevent them from going slack at the bottom.
  • the tendon assemblies 134 must have sufficient axial stiffness to keep the riser/tendon assembly system from going into resonance due to cyclic wave forces.
  • the tubular tendon elements 136 may further comprise conventional oilfield casing joints with a flanged coupling 156 .
  • the casing joints are of various sizes, depending on the required tensile loads. These loads vary on a case-by-case basis, as will occur to those of ordinary skill in the art.
  • the tendon assembly 134 is installed in sections, in a section-by-section sequence, using the drilling rig 122 on the platform. Each section is installed on the deck and lowered using the rig, and the sections are connected using the flanged couplings 156 .
  • the advantages of installing the tendon assembly 134 in sections in this manner using the platform's own drilling rig will be readily apparent to those skilled in the art.
  • FIG. 6B shows a cross section of the tendon assembly 134 of FIG. 6A, showing one of the riser guides or spacers 144 , which is also shown in FIG. 6A.
  • Each of the riser guides 144 couples each tendon assembly 134 to the adjacent risers 126 .
  • the riser guides 144 separate the risers 126 from one another and from the central tendon assembly 134 , thereby preventing the risers 126 and the tendon assembly 134 from clashing or colliding with each other.
  • Each of the riser guides 144 comprises a central tendon conduit 158 , through which the tendon assembly 134 passes, and a plurality of riser conduits 160 through which the risers 126 pass.
  • the riser guides 144 are secured to the tendon assembly 134 , and they may or may not be secured to the risers 126 . As mentioned above, in the preferred embodiments of the invention, there are several vertically-spaced riser guides or spacers 144 , separated by a vertical distance of about 15 ft. (4.5 m) to about 70 ft. (21 m), depending on the design parameters of the particular platform.
  • the tendon conduit 158 and the riser conduits 160 are rigidly connected and separated by a web of separation members 162 .
  • the risers 126 passing through the riser conduits 160 are separated from the central tendon 134 assembly passing through the tendon conduit 158 .
  • the risers are not coupled to the tendon assembly by means such as the riser guides 144 .
  • riser types may be used to connect the wellhead to the platform.
  • the various types of risers include those used for drilling, production, and workover, as will occur to those skilled in the pertinent arts.
  • the risers are drilling risers used with full sub-sea blow-out preventor (BOP) stacks, pressure risers with surface BOPs, and those used with split BOPs (e.g., a surface BOP for well control and a limited function BOP on the seabed).
  • BOP blow-out preventor
  • Still further embodiments may employ production risers and workover risers used with surface trees, sub-sea trees, split trees, wet trees, dry trees, or any other type of tree that may suggest itself to those skilled in the pertinent arts.
  • the platform is designed for vertical entry into the well.
  • the platform may be designed for any other directional entry into the well.
  • the spring characteristics of the risers and/or tendons when acting together, have to be such that the riser system does not respond significantly to the waves, taking into account the mass of the system and the draft of the floating platform.
  • a plurality of risers and/or tendons will act together with a spring characteristic and a strength characteristic for the group of risers and/or tendons. Said differently, the risers and /or tendons act as a system, and their structural and spring properties achieve a uniform behavior for the group of riser and/or tendons.
  • One of the key aspects of this invention is the interaction between the risers or of the risers with the tendons when subjected to the movement of the floating support.
  • the distance between the wellhead on the seabed and the riser slot at the keel increases for the upstream riser and decreases for the downstream riser. Should a tendon be used, these distances will be also different.
  • the spring characteristics in consideration of the hydrodynamic and gravitational forces, have to be selected so that the riser system will act in unison, and the separation between the risers will be maintained to avoid clashing and collisions: as the floating platform moves.
  • FIGS. 1 - 4 illustrate the use of the present invention in a spar type floating platform.
  • the invention may be applied to any deep draft floating platform, such as for example, conventional deep draft submersible platforms or self-installing deep draft submersible platforms.
  • FIG. 8 shows the use of the present invention in a deep draft semi-submersible platform 600 .
  • a vertically restrained buoy 606 which supports a plurality of top-tensioned risers (TTRs) 608 , is guided within the hull of the deep draft semi-submersible platform 600 by a lower guide assembly 610 provided in the base 612 of the floating platform 600 , and an upper guide assembly 614 provided in a work deck 616 supported by the hull.
  • the single buoy 606 supports only a well deck 618 and the TTRs 608 .
  • the buoy 606 can be designed to support the drilling deck and the drilling equipment as shown in FIG. 4 for a spar-type platform.
  • the buoy 606 is vertically restrained by the TTRs 608 only (as shown in FIG. 3 for a spar-type platform).
  • a tendon assembly coupled or uncoupled with the riser can be used to vertically restrain the buoy 606 .
  • this vertically restrained buoy 606 will not be protected by a center well in the splash zone, and will be subjected to wave and current action which can lead to VIV problems.
  • the tension of the riser system can be designed to limit the VIV problem, or VIV strakes (not shown) can be provided on the outer periphery of the buoy 606 .
  • the vertically restrained buoy is guided by guide assemblies provided in the floating platform in at least two locations (upper and lower), whether the platform is a spar-type platform or a deep draft semi-submersible platform. While the floating platform is pitching, the contact loads between the buoy and the guide assemblies provide to the floating platform a restoring moment. This restoring moment allows an improvement (reducing the pitch angle) in the pitch motion of the floating structure. Indeed, this resulting moment is proportional to the weight of the risers supported by the buoy (which can be quite important, especially in deeper water).
  • FIG. 7 shows another embodiment of the vertically restrained buoy.
  • the vertically restrained buoy comprises a single, large buoyancy can.
  • the buoy must be divided into compartments by a plurality of internal lateral bulkheads, thereby increasing the cost of manufacturing the buoy.
  • the intersections between the risers and the bulkheads must be sealed by welding using a heavy welding procedure.
  • a vertically restrained buoyancy apparatus 700 comprises an assembly of a plurality of vertical tubes 702 closely spaced and connected together by vertically-elongated webs 704 .
  • the risers 126 can be arranged around the vertical tubes 702 (i.e. in the interstices defined in between the vertical tubes) and will not have to cross through any buoyancy compartment, thereby avoiding the problem of sealing the intersections of the risers with the bulkheads.
  • the well deck is supported directly by the vertically restrained buoy, the surface trees are attached on the well deck, and there are no relative motions between the surface trees and the well deck.
  • high pressure flexible jumpers can be used to connect each sub-sea tree to the production deck manifold.
  • the single buoyancy apparatus 106 includes the well deck 130 arranged on its top surface. Since the risers 126 are connected to the same buoyancy apparatus 106 , they act as a single riser system, and surface trees 170 connected to upper ends of the risers 126 can be rigidly attached to the top of the buoyancy apparatus 106 .
  • all the surface trees 170 can be connected to a manifold 172 situated on the well deck 130 (rather than the production deck) with rigid piping 174 .
  • the crude oil will be choked down by a pressure-reduction choke 176 in the inlet of the manifold 172 , and, contrary to the prior art, as few as one low pressure flexible jumper 178 (or, alternatively an articulated rigid arm, not shown) can be used to carry the crude oil to the processing equipment on the production deck 116 .
  • the use of just one flexible jumper 178 or perhaps a few flexible jumpers (or articulated rigid arms) will considerably reduce the cost of the riser system as well as the required deck room.

Landscapes

  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Ocean & Marine Engineering (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Earth Drilling (AREA)
US10/616,399 2002-08-07 2003-07-09 Offshore platform with vertically-restrained buoy and well deck Abandoned US20040052586A1 (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US10/616,399 US20040052586A1 (en) 2002-08-07 2003-07-09 Offshore platform with vertically-restrained buoy and well deck
AU2003257153A AU2003257153A1 (en) 2002-08-07 2003-08-05 Offshore platform with vertically-restrained buoy and well deck
BRPI0313324-9B1A BR0313324B1 (pt) 2002-08-07 2003-08-05 "sistema de tubo ascendente para uso em uma plataforma flutuante de calado profundo".
EP03784895A EP1540127B1 (en) 2002-08-07 2003-08-05 Offshore platform with vertically-restrained buoy and well deck
DK03784895T DK1540127T3 (da) 2002-08-07 2003-08-05 Offshore platform med vertikal-holdt böje og vertikal-holdt brönddæk
PCT/US2003/024320 WO2004015239A2 (en) 2002-08-07 2003-08-05 Offshore platform with vertically-restrained buoy and well deck
OA1200500034A OA12898A (en) 2002-08-07 2003-08-05 Offshore platform with vertically-restrained buoy and well deck.

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US10/213,967 US6854933B2 (en) 2002-08-07 2002-08-07 Vertically restrained centerwell SPAR
US47891403P 2003-06-16 2003-06-16
US10/616,399 US20040052586A1 (en) 2002-08-07 2003-07-09 Offshore platform with vertically-restrained buoy and well deck

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US10/213,967 Continuation-In-Part US6854933B2 (en) 2002-08-07 2002-08-07 Vertically restrained centerwell SPAR

Publications (1)

Publication Number Publication Date
US20040052586A1 true US20040052586A1 (en) 2004-03-18

Family

ID=31721404

Family Applications (1)

Application Number Title Priority Date Filing Date
US10/616,399 Abandoned US20040052586A1 (en) 2002-08-07 2003-07-09 Offshore platform with vertically-restrained buoy and well deck

Country Status (7)

Country Link
US (1) US20040052586A1 (da)
EP (1) EP1540127B1 (da)
AU (1) AU2003257153A1 (da)
BR (1) BR0313324B1 (da)
DK (1) DK1540127T3 (da)
OA (1) OA12898A (da)
WO (1) WO2004015239A2 (da)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006077310A1 (fr) * 2005-01-21 2006-07-27 D2M Consultants S.A. Structure de guidage de canalisations reliant le fond marin a un support flottant
WO2008012358A1 (en) * 2006-07-27 2008-01-31 Single Buoy Moorings Inc. Deep water hydrocarbon transfer system
US20100307762A1 (en) * 2009-06-04 2010-12-09 Diamond Offshore Drilling, Inc. Riser floatation with anti-vibration strakes
CN102050212A (zh) * 2009-11-04 2011-05-11 烟台来福士海洋工程有限公司 一种结构合拢导向装置
US20110240305A1 (en) * 2008-12-15 2011-10-06 Per Herbert Kristensen Floating well intervention arrangement comprising a heave compensated work deck and method for well intervention
WO2011137061A1 (en) * 2010-04-26 2011-11-03 Aker Field Development Inc. Dry-tree semi-submersible production and drilling unit
EP2388189A1 (en) * 2010-04-28 2011-11-23 FloaTEC, LLC Spar hull centerwell arrangement
US20120125250A1 (en) * 2010-11-24 2012-05-24 John James Murray Spar hull centerwell arrangement
US20140027124A1 (en) * 2012-07-26 2014-01-30 Cameron International Corporation System for Conveying Fluid from an Offshore Well
US8764346B1 (en) * 2010-06-07 2014-07-01 Nagan Srinivasan Tension-based tension leg platform
US9051782B2 (en) 2010-09-13 2015-06-09 Christopher Magnuson Multi-operational multi-drilling system
US20150315853A1 (en) * 2014-04-30 2015-11-05 Seahorse Equipment Corp Bundled, articulated riser system for fpso vessel
EP2636588A4 (en) * 2010-11-01 2017-04-26 Daewoo Shipbuilding&Marine Engineering Co., Ltd. Drilling ship for a polar region
EP2636587A4 (en) * 2010-11-05 2017-04-26 Daewoo Shipbuilding&Marine Engineering Co., Ltd. Drilling ship for polar region
US11591051B1 (en) 2019-11-21 2023-02-28 NuEnergy Partners, LP Tendon support buoyancy system and method
EP4283092A3 (en) * 2017-06-21 2024-01-10 Horton Do Brasil Tecnologia Offshore, LTDA. Offshore production systems with top tensioned tendons for supporting electrical power transmission

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013062736A1 (en) 2011-10-05 2013-05-02 Seahorse Equipment Corp Method and apparatus for drilling multiple subsea wells from an offshore platform at a single site

Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4217848A (en) * 1976-09-11 1980-08-19 Marine Service Gmbh Floating gas liquefaction installation
US4456073A (en) * 1982-08-24 1984-06-26 Exxon Production Research Co. Flexible connection apparatus
US4606673A (en) * 1984-12-11 1986-08-19 Fluor Corporation Spar buoy construction having production and oil storage facilities and method of operation
US4702321A (en) * 1985-09-20 1987-10-27 Horton Edward E Drilling, production and oil storage caisson for deep water
US4735267A (en) * 1985-03-11 1988-04-05 Shell Oil Company Flexible production riser assembly and installation method
US4740109A (en) * 1985-09-24 1988-04-26 Horton Edward E Multiple tendon compliant tower construction
US4895481A (en) * 1987-01-29 1990-01-23 Doris Engineering Non-rigid marine platform with surface wellheads
US4913238A (en) * 1989-04-18 1990-04-03 Exxon Production Research Company Floating/tensioned production system with caisson
US4995762A (en) * 1988-07-19 1991-02-26 Goldman Jerome L Semisubmersible vessel with captured constant tension buoy
US5147148A (en) * 1991-05-02 1992-09-15 Conoco Inc. Heave-restrained platform and drilling system
US5150987A (en) * 1991-05-02 1992-09-29 Conoco Inc. Method for installing riser/tendon for heave-restrained platform
US5439321A (en) * 1993-03-11 1995-08-08 Conoco Inc. Interruptive mobile production system
US6092483A (en) * 1996-12-31 2000-07-25 Shell Oil Company Spar with improved VIV performance
US6113314A (en) * 1998-09-24 2000-09-05 Campbell; Steven Disconnectable tension leg platform for offshore oil production facility
US6364021B1 (en) * 2000-07-11 2002-04-02 Halliburton Energy Services, Inc. Well management system and method of operation
US6712560B1 (en) * 2000-12-07 2004-03-30 Fmc Technologies, Inc. Riser support for floating offshore structure

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4701321A (en) 1982-05-06 1987-10-20 Soft Sheen Products, Inc. Liquid detergent with sunscreen agent
NO995239D0 (no) * 1999-10-27 1999-10-27 Applied Manufacturing Technolo Momentfritt oppheng for stigerör

Patent Citations (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4217848A (en) * 1976-09-11 1980-08-19 Marine Service Gmbh Floating gas liquefaction installation
US4456073A (en) * 1982-08-24 1984-06-26 Exxon Production Research Co. Flexible connection apparatus
US4606673A (en) * 1984-12-11 1986-08-19 Fluor Corporation Spar buoy construction having production and oil storage facilities and method of operation
US4735267A (en) * 1985-03-11 1988-04-05 Shell Oil Company Flexible production riser assembly and installation method
US4702321A (en) * 1985-09-20 1987-10-27 Horton Edward E Drilling, production and oil storage caisson for deep water
US4740109A (en) * 1985-09-24 1988-04-26 Horton Edward E Multiple tendon compliant tower construction
US4895481A (en) * 1987-01-29 1990-01-23 Doris Engineering Non-rigid marine platform with surface wellheads
US4995762A (en) * 1988-07-19 1991-02-26 Goldman Jerome L Semisubmersible vessel with captured constant tension buoy
US4913238A (en) * 1989-04-18 1990-04-03 Exxon Production Research Company Floating/tensioned production system with caisson
US5147148A (en) * 1991-05-02 1992-09-15 Conoco Inc. Heave-restrained platform and drilling system
US5150987A (en) * 1991-05-02 1992-09-29 Conoco Inc. Method for installing riser/tendon for heave-restrained platform
US5439321A (en) * 1993-03-11 1995-08-08 Conoco Inc. Interruptive mobile production system
US6092483A (en) * 1996-12-31 2000-07-25 Shell Oil Company Spar with improved VIV performance
US6113314A (en) * 1998-09-24 2000-09-05 Campbell; Steven Disconnectable tension leg platform for offshore oil production facility
US6364021B1 (en) * 2000-07-11 2002-04-02 Halliburton Energy Services, Inc. Well management system and method of operation
US6712560B1 (en) * 2000-12-07 2004-03-30 Fmc Technologies, Inc. Riser support for floating offshore structure

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006077310A1 (fr) * 2005-01-21 2006-07-27 D2M Consultants S.A. Structure de guidage de canalisations reliant le fond marin a un support flottant
GB2454409B (en) * 2006-07-27 2011-07-20 Single Buoy Moorings Deep water hydrocarbon transfer system
GB2454409A (en) * 2006-07-27 2009-05-06 Single Buoy Moorings Deep water hydrocarbon transfer system
US20090264033A1 (en) * 2006-07-27 2009-10-22 Single Buoy Moorings Inc. Deep water hydrocarbon transfer system
US7997947B2 (en) 2006-07-27 2011-08-16 Single Buoy Moorings Inc. Deep water hydrocarbon transfer system
WO2008012358A1 (en) * 2006-07-27 2008-01-31 Single Buoy Moorings Inc. Deep water hydrocarbon transfer system
US20110240305A1 (en) * 2008-12-15 2011-10-06 Per Herbert Kristensen Floating well intervention arrangement comprising a heave compensated work deck and method for well intervention
US20100307762A1 (en) * 2009-06-04 2010-12-09 Diamond Offshore Drilling, Inc. Riser floatation with anti-vibration strakes
US8443896B2 (en) * 2009-06-04 2013-05-21 Diamond Offshore Drilling, Inc. Riser floatation with anti-vibration strakes
US9845644B2 (en) 2009-06-04 2017-12-19 Diamond Offshore Company Riser floatation with anti-vibration strakes
CN102050212A (zh) * 2009-11-04 2011-05-11 烟台来福士海洋工程有限公司 一种结构合拢导向装置
WO2011137061A1 (en) * 2010-04-26 2011-11-03 Aker Field Development Inc. Dry-tree semi-submersible production and drilling unit
US8807874B2 (en) 2010-04-26 2014-08-19 Aker Solutions Inc. Dry-tree semi-submersible production and drilling unit
AU2011201823B2 (en) * 2010-04-28 2014-01-16 Keppel Floatec, Llc Spar hull centerwell arrangement
US9422027B2 (en) 2010-04-28 2016-08-23 Floatec, Llc Spar hull centerwell arrangement
EP2388189A1 (en) * 2010-04-28 2011-11-23 FloaTEC, LLC Spar hull centerwell arrangement
CN102320357A (zh) * 2010-04-28 2012-01-18 弗罗泰克有限公司 立柱式平台中心井装置
US8764346B1 (en) * 2010-06-07 2014-07-01 Nagan Srinivasan Tension-based tension leg platform
US9051782B2 (en) 2010-09-13 2015-06-09 Christopher Magnuson Multi-operational multi-drilling system
EP2636588A4 (en) * 2010-11-01 2017-04-26 Daewoo Shipbuilding&Marine Engineering Co., Ltd. Drilling ship for a polar region
EP2636587A4 (en) * 2010-11-05 2017-04-26 Daewoo Shipbuilding&Marine Engineering Co., Ltd. Drilling ship for polar region
US8770131B2 (en) * 2010-11-24 2014-07-08 Floatec, Llc Spar hull centerwell arrangement
US20120125250A1 (en) * 2010-11-24 2012-05-24 John James Murray Spar hull centerwell arrangement
US9133670B2 (en) * 2012-07-26 2015-09-15 Cameron International Corporation System for conveying fluid from an offshore well
US9500046B2 (en) 2012-07-26 2016-11-22 Cameron International Corporation System for conveying fluid from an offshore well
US20140027124A1 (en) * 2012-07-26 2014-01-30 Cameron International Corporation System for Conveying Fluid from an Offshore Well
US9562399B2 (en) * 2014-04-30 2017-02-07 Seahourse Equipment Corp. Bundled, articulated riser system for FPSO vessel
US20150315853A1 (en) * 2014-04-30 2015-11-05 Seahorse Equipment Corp Bundled, articulated riser system for fpso vessel
EP4283092A3 (en) * 2017-06-21 2024-01-10 Horton Do Brasil Tecnologia Offshore, LTDA. Offshore production systems with top tensioned tendons for supporting electrical power transmission
US11591051B1 (en) 2019-11-21 2023-02-28 NuEnergy Partners, LP Tendon support buoyancy system and method

Also Published As

Publication number Publication date
EP1540127A2 (en) 2005-06-15
EP1540127B1 (en) 2006-11-22
AU2003257153A1 (en) 2004-02-25
AU2003257153A8 (en) 2004-02-25
WO2004015239A2 (en) 2004-02-19
BR0313324B1 (pt) 2013-09-10
DK1540127T3 (da) 2007-03-26
BR0313324A (pt) 2005-06-21
WO2004015239A3 (en) 2004-06-03
OA12898A (en) 2006-10-13

Similar Documents

Publication Publication Date Title
US6161620A (en) Deepwater riser system
EP1540127B1 (en) Offshore platform with vertically-restrained buoy and well deck
US6309141B1 (en) Gap spar with ducking risers
US6227137B1 (en) Spar platform with spaced buoyancy
US6092483A (en) Spar with improved VIV performance
US6263824B1 (en) Spar platform
US6854933B2 (en) Vertically restrained centerwell SPAR
AU2008239913B2 (en) Spar structures
US9562403B2 (en) Riser tensioner conductor for dry-tree semisubmersible
US6884003B2 (en) Multi-cellular floating platform with central riser buoy
US20080213048A1 (en) Method for fabricating and transporting an integrated buoyancy system
US8764346B1 (en) Tension-based tension leg platform
US20040182297A1 (en) Riser pipe support system and method
US5575592A (en) TLP tension adjust system
US20040251029A1 (en) Bottom tensioned offshore oil well production riser
US6896062B2 (en) Riser buoyancy system
US6632112B2 (en) Buoyancy module with external frame
US6805201B2 (en) Internal beam buoyancy system for offshore platforms
US20150337514A1 (en) Offshore System with Subsea Riser
US6854516B2 (en) Riser buoyancy system
WO1998029299A1 (en) Spar with features against vortex induced vibrations
KR102477560B1 (ko) 복합 해양구조물
Wanvik et al. Deep water moored semisubmersible with dry wellheads and top tensioned well risers
Xu et al. Design Features of Risers for the Extendable Draft Platform (EDP)
Xu et al. Conceptual Design for Utilizing Buoyancy Can to Support Spar Drilling Riser

Legal Events

Date Code Title Description
AS Assignment

Owner name: DEEPWATER TECHNOLOGIES, INC., TEXAS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:HORTON III., EDWARD E.;REEL/FRAME:014621/0486

Effective date: 20030804

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION