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
  • B63B21/507—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers with mooring turrets
  • B63B21/508—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers with mooring turrets connected to submerged buoy
• • 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
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B22/00—Buoys
  • B63B22/02—Buoys specially adapted for mooring a vessel
  • B63B22/021—Buoys specially adapted for mooring a vessel and for transferring fluids, e.g. liquids
  • B63B22/023—Buoys specially adapted for mooring a vessel and for transferring fluids, e.g. liquids submerged when not in use
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B43/00—Improving safety of vessels, e.g. damage control, not otherwise provided for

Definitions

• Floating support comprising a drum equipped with two mooring line anchor buoys and bottom / surface connection lines
• the present invention relates to a floating support anchored on a disconnectable drum.
• the technical sector of the invention is more particularly the field of underwater oil production in extreme weather-ocean weather zone and more particularly in the Arctic and Antarctic, from floating supports.
• a floating support for oil production generally includes anchoring means to remain in position despite the effects of currents, winds and waves. It also generally comprises means for drilling, storage and treatment of oil and means of unloading to removing tankers, the latter occurring at regular intervals to perform the removal of production.
• the usual name for these floating supports or vessels is the Anglo-Saxon term “Floating Production Storage Offloading” (meaning “floating medium of storage, production and unloading") which we use the abbreviated term "FPSO” as a whole of the following description, or "FDPU” or “Floating Drilling & Production Unit” (meaning “buoyant means of drilling and production”), when the floating support is also used to perform drilling operations with well deviated in height of the slice of water.
• the FPSO When the ocean-weather conditions, ie swell, wind and current are important, even extreme, in the case of storms, it is preferable to anchor the FPSO at a reel, usually located at known manner in the forward third of the ship and in the axis, the vessel being free to turn around said drum in the wind, the current and the swell.
• wind, current and swell exert efforts specific to the hull and superstructures, the FPSO because of its degree of freedom of rotation around the vertical axis ZZ, coming naturally to the position of least resistance.
• the pipes connecting the wellheads are generally connected on the underside of the drum and connected to the FPSO via a rotary joint integrated in the axis of said drum.
• weather conditions can become extreme, such as in the North Sea, in the Gulf of Mexico or in the Arctic or Antarctic zone, the FPSO is generally disconnectable so that it can be sheltered waiting for acceptable operational conditions.
• the present invention relates more particularly to a floating support for submarine oil production in the Arctic or Antarctic zone equipped below its hull with a disconnectable drum from which anchor lines extend to the seabed and pipes. connecting bottom / surface, said shell having in its longitudinal direction substantially flat lateral edges and vertical, and optionally, with, known manner of the proues (front part of the ship) and, preferably stern (rear part of the ship), inclined relative to the horizontal and preferably profiled to form a reinforced pointed bow, capable of breaking the pack ice by simple bending when said pack ice engages force under said reinforced bow.
• the floating supports advantageously have a hull with longitudinal edges substantially vertical to give them optimum oil storage capacity, and better behavior in case of high sea. But a hull with vertical edges is particularly disadvantageous in terms of behavior. facing the pack ice.
• floating supports having, among other means, curved or inclined profile planks for promoting ice breakage are proposed, as is the case for the known bow profiles of the bow. ship with bow inclined to the horizontal.
• a floating oil production support comprising a disconnectable mooring system of anchoring lines at the bottom of the sea and bottom / surface connection pipes comprises in known manner:
• a mooring buoy of said anchor lines and bottom / surface connection lines preferably said buoy being an annular buoy
• said mooring buoy being fixed below the hull of the floating support, to a rotary device comprising a tower-like structure called a "reel", said reed cooperating with the hull within a cavity passing through the hull of the floating support on its entire height, said drum being articulated in rotation with respect to said shell by means of at least one rolling or friction bearing, preferably a rolling bearing so as to allow the rotation of said floating support around a substantially vertical axis ZZ 'of said drum and of said cavity, without causing rotation of said mooring buoy with respect to the same vertical axis ZZ', and
• said bottom / surface connection pipes going up within the cavity to a connection of a plurality of said pipes, said connection being integral with the floating support at the level of the bridge of the floating support, said connection being articulated in rotation so as to allowing rotation of said floating support without causing rotation of said rotary joint fitting.
• the rolling bearing is either located at the level of the floating support bridge or located in the lower part in a wet zone, that is to say that the bearing is immersed, or else in combination of the two previous configurations.
• Embodiments in which the rolling bearing is located exclusively at the level of the bridge are valid only for floating supports of relatively low height, especially less than 15 m. Beyond this, for floating supports, particularly 20 to 25 m height, the horizontal force on the drum resulting from the rotation of the floating support creates a bending of the structure of the drum in its length solicits the mechanical strength of the upper bearing bearing and thus affects the mechanical reliability of operation. On the other hand, when the rolling bearing is immersed in the lower part of the drum, this immersion affects the reliability of operation and the durability of said rolling bearing and in addition creates difficulties in carrying out maintenance operations.
• WO 94/15828 describes a system for quick connection and disconnection of a mooring buoy, in which the mooring buoy comprises an upper part connected to the bottom of the hull of the floating support, more precisely at the level of a mooring cavity extending annularly at the lower end of a cavity passing through the hull of the floating support over its entire height and through which the bottom / surface connection lines rise.
• the mooring buoy also includes a lower portion to which anchor lines are anchored and lower portions of bottom / surface connection lines extending to the bottom of the sea, this lower portion of the mooring buoy. is rotatable through a completely immersed rolling bearing, allowing the rotation of this lower part relative to the upper part of the mooring buoy secured to the hull.
• This type of system with a fully submerged rotating part and fully immersed rolling bearings is not suitable for mooring a large number of bottom / surface connection pipes, for which it is desirable to provide a system in which at least a portion of the rolling bearings is located in an out-of-water zone, so that it can be easier to maintain and operate under less stringent operating conditions.
• a mooring buoy consisting of two independent parts consisting of a first annular buoy on which are moored exclusively said anchoring lines of the floating support and a second coaxial buoy integral with said first buoy. reversible manner, that is to say disconnectable, within the central orifice of said first buoy, said bottom / surface connection lines being moored exclusively on said second buoy.
• the two buoys are entirely contained in a cavity within the shell of the floating support and are thus connected and therefore disconnectable, exclusively by complicated mechanical locking means and very delicate to implement when the efforts become considerable, these being able to reach and to exceed 5 to 6000 tons.
• the object of the present invention is to provide a mooring device reversibly connected to the floating support comprising at least one mooring buoy, device on which are fixed said anchoring lines and bottom / surface connection lines, said mooring device cooperating with a drum, the structure and operation of said docking device being such that the device allows an independent disconnection of the bottom / surface connection pipes, without risk of damaging them, while maintaining the floating support anchored by said anchor lines.
• Another object of the present invention is to provide a system for connection / disconnection of said mooring device, which is fast and based on the principle of creating a positive buoyancy between a mooring buoy and the anchor lines and and / or mooring / mooring connecting lines moored thereto, the buoy connection / disconnection system to be further adapted to an embodiment in which said mooring device is secured under a rotating drum within a cavity extending preferably over the entire height of the hull of the ship, said docking device being articulated in rotation relative to said hull with the aid of at least one rolling bearing, preferably which is not susceptible to be immersed in operation.
• the present invention provides a floating support for oil production comprising:
• said device for anchoring comprising at least one annular mooring buoy, said mooring device being reversibly connected to a drum, and said drum comprising at least one sealed tubular structure, preferably of circular section along said vertical axis ZZ ', having a bottom wall tightly assembled to the lower end of the tubular side wall of said tubular waterproof structure, said drum extending within a cavity passing through the shell of the floating support preferably over its entire height, said drum being articulated in rotation with respect to said shell by means of at least one rolling or friction bearing preferably located above the waterline and / or out of water, preferably a rolling bearing, so as to allow the rotation of said floating support around a substantially vertical axis ZZ 'of said drum and of said cavity, without causing rotation of said docking device with respect to the same vertical axis ZZ', and
• a plurality of links such as lifting ropes attached to each said mooring buoy, preferably to the upper edge of said tubular upper wall of said second mooring buoy, said links preferably extending to the inside the drum while sealingly passing through the bottom wall of the drum, and
• - H 2 is the height of the part of the bottom wall of the drum delimiting said first chamber or respectively second chamber
• S 1 being the cross-sectional area of said first chamber or so-called second chamber
• the weight of the volume of water V 1 corresponds to the pressure of Archimedes applying to the horizontal section S, of said first or second chamber.
• the mooring device of the present invention makes it possible to disconnect and descend to a certain immersion depth below the floating support the second buoy alone, in order to put the first lines of bonds away from turbulence surface and subsurface, while now connected the first buoy on which the anchor lines are moored and thus without undoing the floating support.
• connection / disconnection system is particularly easy to implement, according to the following principle.
• said first or second chamber is filled with water, said vent and guide tube or tubes keeping said first or second chamber substantially at atmospheric pressure during filling, until the water level in said guide tubes is at a height slightly greater than Hi 1 .
• the floating support comprises a plurality of said hoisting cables extending from winches preferably arranged at the deck of the ship or at the top of said reel, above the waterline, said hoisting ropes. optionally extending into a plurality of vent and guide tubes extending vertically within the drum, from a level above the waterline to the bottom wall of the drum which they cross in a sealed way.
• connection / disconnection system comprises at least three said cables and at least three said guide tubes, arranged, preferably, symmetrically with respect to the center of the circular bottom wall of said drum and, preferably, along and near the outer surface of said tubular structure of said drum for said first buoy or respectively close to the inner surface of said tubular structure of said reel for said second buoy, the lower ends of said cables being fixed at the upper face of said first buoy or respectively at the upper edge of said upper tubular wall of said second buoy.
• said upper tubular bottom wall of said second buoy comprises, at its lower end, a bottom wall to which it is sealingly assembled, forming the bottom wall of the chamber of the valves supporting said valves and / or automatic connector parts, and said second buoy comprises, in the lower part, a box constituting a float on the underside of the bottom wall of the valve chamber.
• the upper tubular wall of the second buoy has a height necessary and sufficient to install said valves and connectors automatic connection of the first and second pipes.
• the floating support comprises at least one said pump located preferably in the lower part inside said sealed tubular structure constituting the drum, said pump cooperating with a suction pipe sealingly passing through said bottom wall of the drum, said suction pipe arriving close to the wall of each said first or second chamber when said first or second buoy is in position against said bottom wall of the drum, and said pump cooperating with a discharge pipe for each said first or second chamber, each said discharge pipe opening into said cavity preferably through the wall tubular side of said tubular waterproof structure constituting the drum, preferably in the lower part of said drum.
• the bottom wall of said drum comprises:
• a central preferably circular portion sealingly assembled with said lateral tubular wall of said drum inside thereof and above the lower end of said lateral tubular wall and a peripheral portion surrounding said central portion, preferably an annular peripheral portion sealingly assembled at the lower end of said lateral tubular wall or on the outer face of said tubular side wall of the drum, offset in height downward with respect to said central portion so that the ends lower portions of said second connecting conduits preferably comprising connector portions, on the underside of said central portion of the bottom wall, being located above the lower end of the tubular side wall of the tubular sealed structure of the drum .
• This embodiment is particularly advantageous in that it allows that said first buoy is not likely to damage, when disconnected, the lower end of the second connecting lines, including the part of automatic connectors, when the said first buoy is dropped, given the considerable booster forces to which said first buoy is subjected, when the FPSO undergoes significant horizontal displacements due to swell, wind, current, or drifting ice.
• the first buoy is thus disconnected only after disconnecting and releasing said second buoy relative to the central orifice of said first buoy.
• This offset between the central portion and the peripheral portion of said bottom wall forms a cavity delimited by the lower end of the inner surface of the tubular side wall of the drum and the underside of the central portion of the bottom wall.
• This cavity forms a centering catch so that it can hold and wedge in position said second mooring buoy when it is pressed on the underside of said bottom wall to allow the connection of said first and second lines of connection using said connectors.
• centering means make it possible to facilitate the centering of the upper tubular wall of said mooring buoy with respect to said drum, in approaching movement against the underside of said bottom of the drum and, if necessary, facilitate the connection.
• the floating support comprises:
• each of said first or second mooring buoy comprises abutments or protective cleats limiting the crushing of said seal and ensuring the vertical load transfer between said first or second buoy and the drum when said first or second buoy is applied. against the bottom wall of said drum, said O-rings being compressed between the underside of the bottom wall of said drum and said first or second mooring buoy, said protective catch being capable of cooperating with an articulated movable safety lock secured to the underside of the bottom wall of said reel, such that said first or second mooring buoy is made integral. said drum when said safety lock is engaged below said protective catch.
• said upper tubular wall of the second buoy and / or the tubular side wall of the sealed tubular structure of said reel comprises (s) a filling valve cooperating with filling pipes connecting the sea water and the interior of said valve chamber, and, preferably, said tubular wall of said valve chamber having a large-sized watertight hatch, adapted to allow an almost instantaneous filling of said valve chamber with seawater when one opens said hatch.
• the bottom wall of the drum comprises a inspection hatch of said valve chamber.
• valve chamber Since it is possible to empty the valve chamber, it allows the personnel to intervene dry in said chamber for maintenance and, if necessary, the implementation of the valves and automatic connectors ensuring the connection between said first and second conduits.
• the present invention also provides a method of implementing a floating support according to the invention, in which the connection of a said first or second buoy is carried out on the underside and against the bottom wall of a said drum, and the following steps are carried out: a- one immersed a said first or second mooring buoy, to which are anchored said anchor lines or respectively said first connection lines bottom / surface, and b- attaching the lower end of the hoisting ropes to said first or second buoy, said floating support being positioned such that said first or second buoy is substantially oriented in the vertical axis ZZ 'of said cavity, and c- operating said winches to raise said first or second buoy until said seals, including O-rings for the first said mooring buoy or said seal for said second mooring buoy ( en) t applied against and on the underside of the bottom wall of said drum, thereby forming a said first or respectively second chamber filled with seawater, said guiding tubes cooperating with said first or second chamber also being filled with sea water to a height H 0
• H 2 b represents the height with respect to the seabed of the upper edge of the upper tubular wall of the second buoy and that of the underside of the bottom wall portion of the reel when in contact and S b is the cross-sectional area of the upper tubular wall of said second buoy or the surface of the bottom wall of the drum delimited by the upper edge of the upper tubular wall of the drum when in contact.
• H 2a represents the height, with respect to the seabed, of the upper face of the first buoy and that of the underside of the peripheral portion of the bottom wall of the reel when in contact
• S 3 is the section of the annular surface of the cross section of said second chamber delimited by the two joints of the upper face of the first buoy when in contact with the underside of the peripheral portion of the wall of bottom of the drum.
• the lower ends of said lifting cables are detached from said first or second mooring buoy and, preferably, mechanical locking means of said first or second buoy are engaged.
• mooring making it integral with the bottom wall of said drum, preferably with the aid of an articulated movable safety lock adapted to cooperate with protective stops preventing crushing of said seals or said compressed gasket between said first or respectively second mooring buoy and the underside of the bottom wall of the drum.
• said first or second mooring buoy and said bottom wall of the drum, and d-it finishes filling the guide tubes in communication with the chamber, which causes the disconnection of said buoy.
• This two-stage disconnection mode is advantageous because, after step b- and up to step d-included, the second buoy is held in position by the hydrostatic thrust and the release process. the second buoy is always reversible by simply emptying the chamber. This allows to provide a phase of intermediate disconnection or waiting phase, in case we are not sure of wanting to disconnect the second mooring buoy but that, if necessary, we want to be ready to be able to do this disconnection as quickly as possible, by simply filling the guide tubes in accordance with step e-above.
• the preparatory phase which is still reversible is calmly carried out, this phase possibly taking several hours in the case of burning of the iceberg. depressurization gas by the edge flare.
• the second phase (step e-), the latter being irreversible, lasts only a few tens of seconds, or even a few minutes, to obtain the release of the buoy, and therefore the almost instantaneous release of the FPSO of its bottom / surface links, or in the case of the first mooring buoy, its anchorage.
• FIG. 1 represents in section and in side view of a floating support of the FPSO type anchored on a reel within an ice floe
• FIG. 2 represents in section and in side view an FPSO subjected to extreme horizontal thrust from drifting ice floe 31,
• FIG. 3 shows a side view the release of a second buoy supporting the flexible connection lines 14, the FPSO being held in position by the anchoring lines integral with a said first buoy,
• FIG. 4 is a side view of the subsequent release of said first buoy in order to release the FPSO from the pack ice
• FIG. 5 represents, in side view, an FPSO taking up a position vertically of said first and second buoys, in order to reconnect with said first buoy comprising the anchoring lines 13, then with said second buoy secured to said first connection lines; bottom-surface type flexible pipes,
• FIG. 6 shows in section and in side view, the drum passing right through the FPSO, the bottom wall of the drum supporting a said first annular buoy to which the anchor lines are moored and a second buoy 1-2. having a valve chamber in which said first bottom-to-surface connection lines are connected, said valve chamber in continuous operation being made accessible to the personnel 10 2 since it is then at atmospheric pressure, - Figure 7 shows in section and in side view the disconnection of said second buoy of the drum by flooding said second valve chamber with sea water, during the release procedure with accompanying handling cables 20b, 21 b,
• FIG. 8 shows in section and in side view the reconnection of the second buoy on the drum by means of winches and cables
• FIG. 9 represents a sectional view along II of FIG. 8 at the level of an upper rolling bearing 5 2 .
• FIG. 10 shows in section and in side view the drum and deballasting by means of a bilge pump, the upper part of the second buoy corresponding to the valve chamber 30,
• FIG. 11 shows in section and in side view of the initial step of the disconnection of the second buoy with respect to the reel by flooding the valve chamber with sea water, during the drop procedure,
• FIG. 12 shows in section and in side view the fastening elements between the underside of the drum and the upper part of the second buoy, and means for flooding the valve chamber by sea water.
• FIG. 13 shows in section and in side view the deballasting device by means of a bilge pump, of the upper part of the chamber of the first buoy,
• FIG. 14 shows in section and in side view the flooding device of the chamber of the first buoy, the disconnection of said first buoy has occurred.
• FIG. 15 shows a top view of the two first and second buoys arranged coaxially.
• FIG. 1 shows in section and in side view, a FPSO type floating vessel or support 10 anchored on a disconnectable mooring system 1 fixed on the underside of a drum 2 comprising a first buoy 1-1 on which are moored anchor lines 13 and a second buoy 1-2 connected to underwater wellheads, not shown, by flexible pipes called first bottom-surface connection lines 14 in plunging chain configuration 14a until to a subsurface float 15 supporting said hose.
• the float 15 is held by a cable 15a connected to a dead body 15b at the bottom of the sea, then said flexible pipe 14a is extended in chain configuration 14b to the bottom of the sea 50, then to the said heads. well.
• connection / disconnection modes of said first and second buoys on the underside of the drum 2 independently of each other are described below.
• FIG. 2 shows in side view an FPSO pushed by a drifting ice floe 31, which causes an offset ⁇ L which has the effect of modifying the configuration of the chains 14a of the connecting lines 14 on the left, to the extreme, a force F applying to the first buoy 1-1 is transmitted to the drum 2 of the FPSO, now the latter in position.
• FIG. 5 shows, in side view, an FPSO coming to take up position vertically from the first and second stabilized buoys respectively at heights Hb-Ha above the seabed 50, the FPSO will recover and connect successively the first mooring buoy 1-1, then the second buoy 1-2.
• FIG. 6 represents in section and in side view the docking device 1. It comprises two buoys 1-1, 1-2 arranged coaxially with respect to each other and with respect to the axis ZZ 'of the bottom wall 2b of said drum, a first buoy 1-1 being an annular buoy on which are anchored said anchoring lines 13, and said annular buoy having a central orifice 1-3 containing a second buoy 1-2 on which are moored said first bottom-surface connection lines 14, said second mooring buoy 1-2 comprising an upper tubular wall la, hereinafter referred to as a valve chamber, inside which said valves 8 and connectors 7 at the upper end of said first connecting lines 14.
• Said docking device 1 is reversibly connected to a drum 2.
• Said drum comprises a sealed tubular structure 2, with a circular section along said vertical axis ZZ ', comprising a bottom wall 2b sealingly assembled at the lower end. of the tubular side wall 2a of said tubular waterproof structure.
• Said drum 2 extends within a cavity 4 passing through the hull of the floating support over its entire height.
• Said drum is articulated in rotation relative to said shell by means of 3 rolling bearings 5i, 5 2 , 5 3 , one of which is situated above the waterline 32 and / or out of water.
• Second connecting lines 14c extend between the upper end of said first bottom / surface connection conduits 14 to which they are connected and the bridge of the floating support 10i. Said second connecting ducts 14c pass sealingly through the bottom wall 2b of the drum 2 and up through the cavity 4 to a coupling 3 of a plurality of said second pipes 14c, said coupling 3 being integral with the floating support at the level of the bridge 10i of said floating support.
• Said connector 3 is of the type with a rotating joint, articulated in rotation on the bridge so as to allow the rotation of said floating support without causing the rotation of said coupling.
• the lower ends of said second connecting lines on the underside of said bottom wall of the drum are connected to the upper ends of said first connecting pipes 14 via connectors 7 cooperating with isolation valves 8.
• the seawater is present inside said cavity 4 of the FPSO and outside the drum.
• the drum 2 comprises at its upper end an upper platform 2c, of larger diameter than the lateral tubular wall 2, said platform bearing, in its peripheral parts protruding from the lateral tubular wall 2, against the step 10a at the end upper cavity 4.
• the mooring system at the reel comprises three rolling bearings, namely: an upper support bearing 5i, and
• Said bearings 5i, 5 2 , 5 3 are friction bearings or rolling bearings, preferably rolling bearings. It may be more particularly rollers or rollers interposed between: the inner wall A 1 of the cavity 4 and the external surface of the lateral tubular wall 2, with regard to the rollers or the lateral guide rollers 5 2 and 5 3 , and
• said tubular structure 2 and said inner cavity wall A 1 have a circular section.
• the rollers or rollers of the lower and upper lateral guide bearings 5 2 and 5 3 are more particularly arranged with their axes of rotation in a vertical position.
• said rollers or rollers are arranged with their axes of rotation in a horizontal position bearing on the redan la, the platform 2i resting on the edge of said rollers 5i.
• the diameter outside said tubular structure of the drum 2 may exceed 25m, more particularly from 10 to 20m and its wet height is generally greater than 20 m, can reach 25 m, or more in the case where the hull of the floating support extends over a height of 50 m as in some cases.
• connection / disconnection system of said first and / or respectively second mooring buoy (s) 1-1, 1-2 with respect to said bottom wall 2b of the drum allows the connection / disconnection of each of said first and / or respectively second mooring buoy independently of one another.
• the bottom wall 2b of said drum comprises:
• the FPSO is in cold waters in which icebergs or large, large ice sheets floating on the surface of the sea can move. 32
• said second buoy is disconnected to lower the said first pipes to a certain depth And, disconnects the said first buoy, commonly called “spider buoy”, that is to say “spider buoy”.
• the internal buoyancy of said first and second buoys that is to say the volumes of the annular casing 40b voids inside the first buoy 1-1 and the volume of the box 30b on the underside of the valve chamber 30 of the second buoy are adjusted so that said first and second buoys stabilize at depths Ha and respectively Hb above the seabed, corresponding for example to distances of 50 to 100m with respect to the surface of the sea 32, thus putting all the anchoring lines and hoses safe, as shown in the same figure 5.
• FIGS. 6 to 11 there is shown, for the sake of clarity, the second buoy 1-2 with a single said second conduit 14c passing through the inside of the drum from a female portion 7b of automatic connector 7 on the underside of the bottom wall 2c of the drum.
• the second buoy is handled thanks to the cables 20b, at least two cables, preferably three cables, preferably, regularly and uniformly distributed inside said drum close to the cylindrical surface. internal wall of the tubular structure 2, and connected to winches 20a, secured to the drum and installed in the upper part, largely above the waterline 32, preferably on the platform 2c. Said cables 20b each pass through a guide tube 20c-2, the latter protruding by several meters, for example 5m, the maximum level of the maximum swell striking the side of the ship, said maximum level being well above the level of the sea at rest 32 as shown in said FIG. 7.
• Said guide tube 20c-2 extends vertically downwards and passes in a sealed manner through the central portion 2b1 of the bottom wall 2b of the drum 2.
• the level of the seawater inside the guide tubes 20c-2 remains substantially the same as at the ship's side, that is to say at the corresponding level H 0 , in said figure, at the level of the sea 32.
• the level of water in the guide tube 20c-2 can not reach the top of the tube 20c-2, and the seawater is not likely to invade the inside of the drum 2.
• the tubular side wall 2a of the drum is traversed in its structure by guide tubes 20c-I, preferably at least 3 regularly distributed, which extend from the platform 2c to the lower end of the side tubular wall 2a through the peripheral portion 2b2 of the bottom wall 2b of the drum.
• guide tubes 20c-I preferably at least 3 regularly distributed, which extend from the platform 2c to the lower end of the side tubular wall 2a through the peripheral portion 2b2 of the bottom wall 2b of the drum.
• cables 21b hooked at their upper end on winches 21a resting on the platform 2c and hooked at their lower ends on the upper surface 40a of said first annular ring buoy.
• the first mooring buoy is therefore handled by the cables 21b, at least two cables, preferably three cables, preferably regularly and evenly distributed inside the tubular wall 2a of said drum.
• the FPSO is positioned substantially vertically to the two buoys, and a ROV (automatic submarine intervention piloted from the surface) is connected to said first buoy 1-1, the end of the cables 21b down to the depth desired by deviating winches 21a.
• the first buoy is then raised towards the bottom 2b of the drum by synchronized winding of all the winches, until the upper part of the buoy comes into contact with the lower part 2b2 of the drum.
• the first chamber 40 is then unglazed as detailed in FIG. 13 using a pump 22 and said first buoy is then secured to the reel thanks to the buoyancy force acting on the surface delimited by the two seals 200a-200b. because said first chamber 40 is then substantially at atmospheric pressure.
• the ROV connects the upper edge Ib of said second buoy 1-2, the lower end of the cables. 20b, descended to the desired depth by unscrewing the winches 20a.
• the second buoy is then raised towards the bottom of the drum by synchronized winding of all the winches, until the upper part of the buoy comes into contact with the lower part of the drum.
• the chamber of the valves 30 is then unpacked as detailed in FIG. 10 using a pump 22 and said second buoy is then secured to the reel thanks to the buoyancy force acting on the surface delimited by the gasket 100, since said chamber 30 is then substantially at atmospheric pressure.
• the upper part of the second buoy 1-2 is constituted by an upper tubular wall la, preferably of circular section, delimiting a first chamber or chamber of the valves 30 enclosing the upper ends of the first ducts 14 sealingly crossing the bottom 30a of the chamber 30, as well as the buoyancy chamber 30b located on the underside of said chamber of the valves 30.
• Said upper ends of the first ducts 14 being equipped with valves 8 and and / or male 7a or female 7b parts of automatic connectors 7.
• the valves 8 and male parts 7a of automatic connectors 7 at the upper end of the first conduits 14 are supported by the bottom of the valve chamber 30a.
• the circular seal 100 preferably an O-ring, is applied to the upper edge Ib constituting the edge of the upper tubular wall of the second buoy 1-2.
• the circular elastomer seal 100 integral with the buoy 1-2 is compressed between the under-face of the drum of the upper part of the second buoy, a tab 101 secured to said second buoy, limits the crushing of said seal and ensures the transfer vertical load due to buoyancy, between said second buoy and the drum.
• tabs 101 are applied against the outer surface of the tubular wall 1a and extend below it, that is to say below the level of the underside of the bottom wall 2c of the tubular structure 2, in order to allow the recovery of the horizontal forces experienced by the mooring buoy 1-2.
• the lower end 27 of the tubular side wall 2a of the drum below the central portion 2b2 of the bottom wall serves as a guide means 27 for centering the second buoy relative to the drum, and thus facilitate the connection male parts 7a and female 7b automatic connectors.
• the lower end 27 of the tubular side wall 2a of the drum allows the recovery of horizontal forces experienced by the mooring buoy 1-2.
• the tension is maintained in the cables 20b, 21b and the deballasting of the valve chamber 30a is carried out as detailed in FIG.
• a pump 22 draws water through a suction pipe 22a sealingly through the bottom 2c of the drum and discharging the water into the sea through the discharge pipe 22b sealingly passing through the reel 2.
• the water inside the guide tubes 20c-I is at level H 0 , corresponding substantially to sea level, but as soon as the pump has evacuated a few hundred liters, the The water will reach the Hib level because the diameter required for the pipes is related to the diameter of the lifting cables 20b and is advantageously reduced to a minimum.
• an internal diameter of 300 mm guide tube and a height H 0 -H 2 b 20m, within which is installed a lifting cable of 150mm in diameter corresponds to a volume of water about Im3, i.e., an overall volume of about 4m3 for a four-strand lifting system.
• a deballasting pump of 500m3 / h will thus empty the entire height of the said guide pipes in approximately 30 seconds, and then begin to empty the valve chamber whose volume is approximately 2,000 m3 for a 5m chamber. height and 22.5 m in diameter.
• the valve chamber 30 When the valve chamber 30 is empty, it is at atmospheric pressure and is made accessible by a manhole 24 provided with a sealed hatch 24a in the closed position when the second buoy is disconnected, or the valve chamber is being purged or refilled.
• a safety latch device 14 consisting, for example, of an articulated mobile part 102 integral with said under face of the drum, cooperating with a catch 101 integral with the annular buoy, said cleat being for example common with the stop limiting the crushing of the elastomer seal 100.
• the access hatch 24b is sealed in the chamber of the valves, and
• the valve 25, shown in FIG. 11 is opened which puts in communication , through the filling lines 25a-25b respectively passing through the tubular side wall 2 at the bottom of the drum and the central portion 2b1 of the bottom wall 2b of the drum, the sea and said valve chamber, and thus begins the filling of the valve chamber, the guide tubes 20c-2 serving as vent by maintaining the valve chamber substantially at atmospheric pressure during all said filling, and - the filling is stopped by closing the valve 25, when the valve chamber 30 is completely filled, which represents a volume of seawater of about 2000 m 3 in the previously described example, that is to say when the water level H2b of the level within the the chamber of valves is reached.
• the safety latches 102 are unlocked by pivoting them from their engaged position 102a to their retracted position 102b, and
• At least one of the valves 25 is opened in large so as to complete the filling of the guide tubes 20c-2, which represents a small volume, of the order of a few cubic meters in the example described above.
• Vib S b x (H 0 -Hib).
• the second buoy begins to naturally release the drum and the fact that said second buoy begins its descent down, the seal 100 is not waterproof and then leaves between sea water with almost infinite flow.
• the second buoy is found with a hydrostatic level corresponding to the level of the sea, that is to say at the level HO, and said second buoy is precipitated down with a considerable force corresponding to its own weight, c ie 500-1500 tons, thus freeing the FPSO from its anchorage on a drum, almost instantaneously.
• a gasket with a thickness of 25 mm will require, in the above-mentioned example of a chamber with valves of 22.5 m in diameter, a complementary supply of seawater of approximately 10 m 3, which does not dramatically increase the disconnection time.
• valve chamber 30a It is also possible to fill the valve chamber 30a with valves 26 and lateral filling lines 26a-26b passing through said upper tubular wall 1a of the second mooring buoy 1-2, as shown in FIG. 12. .
• said tubular upper wall 1a of the second mooring buoy has been described as being defined by a cylindrical surface of vertical axis ZZ ', preferably of circular section.
• said upper tubular wall la can be defined by a surface of revolution of vertical axis ZZ 'whose right generator is inclined relative to the axis ZZ', said upper tubular wall then having a frustoconical shape, or said generator may be curved, the essential part being to define a side wall whose upper edge Ib is able to come into contact with the underside of the central portion 2b2 of the bottom wall 2b of the drum 2, on the one hand , and, on the other hand, whose lower end is sealingly assembled on the periphery of the bottom wall of the chamber 30, so as to define a chamber of the valves 30a sealed when the upper edge of the side wall of said valve chamber comes into contact with the central portion 2b1 of the bottom wall 2b of the drum 2.
• the winches 20a-21a are installed at the deck of the FPSO and the corresponding lifting cables 20b-21b pass through the guide tubes 20c-1, 20c-2, the latter also playing the role of vent, but it remains in the spirit of the invention if we integrate the winches in the structure of the drum at its bottom.
• the winches are then directly into the water and the cables connected directly to the buoy: there is then at least one pipe 20c-l, 20c-2 which then has a role of vent.
• the system and method of connecting / disconnecting said first buoy 1-1 is similar to that of the second buoy described above.
• the pumping means cooperating with a suction pipe 22a passing through the peripheral portion 2b2 of the bottom wall 2c and a discharge pipe 22b passing through the tubular side wall 2a and opening into the of the cavity 4, allow emptying the interstitial chamber 40 between the two seals 200a and 200b delimiting said second chamber 40, when the first buoy is pressed against the bottom wall of the drum.
• the two elastomeric seals 200a-200b, integral with the first ring buoy 1-1 are compressed between the underside of the drum and the upper part of the first buoy.
• Cleats 101a, 101b comprising a male portion 101a secured to the upper face 40a of the first buoy cooperates with complementary male parts 101b in which they can be wedged under the side of the peripheral portion 2b2 of the bottom wall 2b of the drum.
• stops or cleats 101a, 101b can limit the crushing of the seals 200a and 200b and these cleats can cooperate with safety locks (not shown) making the first buoy integral with the peripheral portion 2b2 of the bottom wall 2b of the drum.
• cleats 101a, 101b serve as centering means of the first buoy relative to the bottom wall of the drum and allow to take up at least part of the horizontal forces experienced by the first buoy.
• a valve 25 and pipes 25a, 25b passing through the side wall 2a of the drum allow to fill the chamber 40 with the water coming from the inside of the cavity 4.
• the buoyancy pressure is applied to the limited area respectively by the seal 100 in the case of the second buoy, and limited by the joints 200a-200b in the case of the first buoy.
• the upward vertical thrust is a function of the difference H 0 -H, where H is the level of free water within the guide tubes 20c-1, 20c-2.
• the pumping 22 will very quickly lower the water level in the guide tubes 2Oc-I, and as soon as the Hia level is reached, said buoy 1-1 is plated the continuation of the pumping will have the effect of increasing the buoyancy of Archimedes and the safety factor of the system is then a function of the height Hi 3 -H 23 .
• the second buoy which will be, in calm weather, connected or disconnected at a level Hi b , and in case of extreme conditions will be dropped to a level H between the level Hi b and the level H 2b .
• a first buoy 1-1 having an internal peripheral seal 200a of 25m in diameter and an external peripheral seal 200b of 42m, a value of H2a of 22m, is subjected, when the plane of the joints is at a distance of depth of 20m, with an Archimedes pressure of about 20,000 tonnes directed upwards.

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• 2008
  • 2008-09-05 FR FR0855984A patent/FR2935679B1/fr not_active Expired - Fee Related
• 2009
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  • 2009-08-28 US US13/057,630 patent/US8449341B2/en active Active
  • 2009-08-28 CA CA2731070A patent/CA2731070C/fr active Active
  • 2009-08-28 DK DK09740502.1T patent/DK2318267T3/da active
  • 2009-08-28 EP EP09740502.1A patent/EP2318267B1/de active Active
  • 2009-08-28 WO PCT/FR2009/051641 patent/WO2010026334A1/fr active Application Filing
  • 2009-08-28 RU RU2011101937/11A patent/RU2485003C2/ru active

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