NO802427L - OFFSHORE OIL PRODUCTION. - Google Patents

Description

The present invention relates to the storage and transfer of

oil from an offshore well.

At present, oil is mostly produced from offshore wells

led to pipelines for crude oil, which pipelines extend along the seabed to a suitable point on land. Oil from the pipeline is usually stored in large oil storage facilities at or near the coast. Construction of large oil storages on land and in particular

construction of submerged crude oil pipelines entails a very large capital expenditure. One purpose of the present invention is to provide means for the delivery of oil from one or more offshore wells, e.g. an oil field, which does not require the construction of large pipelines on the seabed to land and which makes it unnecessary, or at least reduces, the necessity of building storage on land.

According to one aspect of the present invention there is provided

a method for delivering oil from an offshore well to land, which method comprises the steps of (a) supplying oil from the well to a floating storage vessel stationed near the well; and (b) transferring oil by means of a flexible pipeline from the floating storage vessel to a tanker that runs between land and the floating storage vessel.

According to another aspect of the invention, an oil storage vessel is provided which is provided with (a) a flexible hose for the delivery of oil, one end of which is arranged for connection with the vessel's oil storage; and (b) a support system which can be used to carry said flexible hose or a further hose connected to the flexible hose so that it extends from the stern of the oil storage vessel towards another

vessel. The vessel preferably comprises a disk mounted in

a guiding device for movement mostly along the ship's side

axis, which disk is constructed and positioned so that the flexible hose can be passed around the disk and fed out from it.

According to a third aspect of the invention, there is provided an apparatus for mooring a vessel at sea, which apparatus comprises a base placed on the seabed; a fluidic swivel;

at least one universal joint; and a distance buoy with at least one mooring chain attached to it by means of which the vessel can be moored to the apparatus.

Oil is preferably supplied continuously to the oil storage vessel and removed from it in portions (with the help of the tanker).

The oil is preferably supplied directly to the oil storage vessel from an underwater wellhead, but it can however also be supplied to the vessel from an oil production platform.

The floating storage vessel will mainly be moored to a location on the seabed at or near the wells using means that allow the vessel to assume a position in accordance with the prevailing weather conditions. The mooring may consist of several anchor chains or other systems that provide a connection with the bottom. It is preferred to use a submerged anchoring arrangement, preferably in the form of a buoyancy chamber connected to a gravity base and/or piled base in shallow water or a buoyancy chamber connected to one or more buoyancy-provided riser columns which in turn are connected to a gravity base for large water depths for both the shallow and deep water systems, "mooring chains" are attached to the uppermost buoyancy chamber called a "distance buoy" and are fed into the ship at a point at its keel. The "mooring chain" can be. a mooring line consisting entirely of chain, or it may be a combination of chain and wire. The importance of the chain lies in its weight and size-changing ability due to changes in the length and shape of its chain link. Eh procedure for mooring a vessel at sea using

of such an apparatus is also provided. Dynamic positioning can be used if necessary by the storage vessel to ease disproportionate loads in the mooring and to keep

the vessel in the most appropriate position when wind, waves and current create difficult sea conditions. Three references are

preferably available to hold the storage vessel, e.g.

a ship, in position relative to the mooring.

. For shallow and deep water applications, the yawing movements of the vessel are taken into account in the hose couplings in the storage vessel (e.g. a ship) to avoid twisting of the hose(s). This can be done in the case of a single riser or a single underwater hose by means of a removable seal or as described below. When several hoses are used, a rotating plate built into the ship above the waterline can be used. The risers or submerged hoses are connected to suitable connecting ports on its underside. rotating disc. Flexible, helically coiled tubing is attached to the connection ports on the top of the rotating plate. These flexible hoses form an orderly helical arc. That will be enough flexibility in the curvature and bending of the hoses to allow the ship to turn out of position relative to the rotating plate 90° both to starboard and port without the need to use rotatable seals for the hoses. When mooring in shallow water, oil will pass into the base and to the fluid swivel mounted immediately above it, from where it will continue in one or more hoses to the storage vessel. When mooring in deep water (mostly over 55 m), oil will . pass from a collector pipe on the seabed through a flexible pipe to the riser above the shelf. The oil will then be passed through the riser or a pipe attached to the riser

and runs along its entire length. At the top of the riser, the oil will continue through the fluid swivel and out to one or more flexible hoses leading to the storage vessel. In the preferred system for shallow water there is one joint connection, while in the system for deep water there are preferably two or more joint connections. The fluid swivel is arranged above the plinth in the shallow water system and at the top of the riser in the deep water system. In both cases, the fluid swivel is preferably placed at a depth that is not

greater than that divers can reach it without using anything but

air as breathing gas. Before connection to the storage vessel can

the mooring chain hangs vertically from the top of the chain beam on the distance buoy, its end being attached to a down-hanging line and a marking buoy on the surface. The underwater hose(s) attached to the fluid swivel is advantageously hung from a chain line and held with its end at approx. 20 m deep below SWIi using a line and a marker buoy.

Both the shallow and deep water systems can be provided with an additional section so that they will break the surface. In this case, the additional section is preferably flange-connected. with the spacer buoy, and the mooring shackle is attached to the top of the further section. With such a surface-breaking section, it is advantageous to use a mooring cable instead of a chain beam and a chain. The reason for incorporating this duality is so that an oil operator can only use transport vessels in the initial and final production phases of the field's development and can use a storage vessel when the size of the oil production makes this necessary.

In shallow water, the preferred arrangement for mooring the floating storage vessel uses a chain tube which is built into the vessel and which guides the chain to a winch mounted on the back deck. The chain tube advantageously has a bell-shaped mouth to distribute the mooring load and can be located between the bow and the vessel's center of rotation. The vessel will thus be able to rotate or adjust according to the weather around the mooring chain pipe - when the weather conditions change.

In deep water, a preferred arrangement for mooring the floating storage vessel utilizes a spindle cylinder built into the vessel, which cylinder contains the mooring equipment, underwater hose handling equipment, and diving equipment. The spindle cylinder in the ship is placed in one suitable place, mainly a. or elsewhere between the bow and 1/3 aft, preferably just forward of the center of rotation. The vessel will thus be able to rotate or align itself according to the weather around the chain tube in the spindle cylinder when the weather conditions change.

The collecting pipe on the seabed is attached to the oil line at the riser above the bottom link connecting the riser and the plinth. The hose guide for the hose leading from the fluid swivel is balanced and/or supported. Before connecting to the tanker, the mooring chain hangs vertically from the chain boom at the top of the distance buoy, and its end is attached to a line and marker buoy. The underwater hose attached to the swivel hangs in a chain line with its end approx. 20 m water depth using a line and a marking buoy. The distance buoy in both the shallow and deep water systems is particularly diminutive. sioned and shaped for optimum resistance and restoring forces and is usually submerged. A section can be added to this so that it will break the surface. In this case, the added section is preferably flanged to the spacer buoy, and the mooring shackle may be attached to the top of the additional section. When using the surface breaking section, a mooring line can preferably be used instead of a chain. The reason for incorporating this duality is to give an oil operator the opportunity to use only tankers in the initial and final production phases of field development and to use one storage vessel when the size of the oil production dictates such a vessel.

The floating storage vessel can moor with its own help

. the submerged mooring as soon as it has been established that the underwater hose has not wrapped itself around due to current action.the vertically down-hanging mooring chain.

In the shallow water system, the storage vessel will approach the mooring between the marking buoy for the hose and the marking buoy for the mooring chain. The mooring chain buoy and its line will then be hoisted aboard one side of the ship and the hold. The mooring chain is attached to a continuous wireline that passes around the hull in a cleat and into and through the mooring chain tube. When the chain reaches the top of the tension chain it will be passed over a play and the excess chain will be stored in a chain box.' The buoy and the line marking the underwater hose will then be hauled aboard the other side of the storage vessel just ahead of the hose-disc system which is preferably mounted on the ship's bulkhead.

A precursor extending the length of the disc system from an on-board oil sump and through the hose control is attached to the hose which is currently attached to a puller on the redoubt. The hose is lowered and led through the hose guide, above

the disk and along the track to the collector pipe where its end is connected by a coupling. Depending on how many fluids

is fed from/to the mooring's fluid swivel, a multiple hose system using hose sheave systems on both sides of the ship can be used. In the deep water system, the storage vessel will approach the mooring between the mark buoy for the hose and the mark buoy for the mooring chain. The mooring chain buoy and its line are hauled aboard to one side and stowed. The mooring chain is attached to a continuous wireline which is routed around the hull in a knot and into and through the mooring pipe.

When the chain reaches the top of the mooring pipe, it is secured while the end is passed over a play. Surplus chain is stored in a chain box. The buoy and connecting line that marks

. the underwater hose is then hoisted aboard the other side of the ship.

The hose or hose bundle is attached to a continuous wireline which is led around the hull in a knot and into and through the hose pipe. When the connecting end(s) of the hose(s) are reached to the connection point, the connection is made.

In both the shallow water and deep water systems, the length of the mooring chain in the water would depend on the weather conditions and the vessel's draft. In the shallow water system, the length of hose in the water is adjustable, while in the deep water system the length of hose in the water remains fixed.

The means for transferring oil from the storage vessel to a transport tanker preferably comprise 1) manual or automatically controlled tension release mooring winch with line, a mechanical clamping device and 2) one or two oil hoses. ■ The mooring line is preferably provided with "colour marking" so that the length of line that has been issued at any time can be seen by the visible colour. The line is attached to the cargo tanker by means of a towing winch and/or stoppers. 01jeovering hoses run over appropriately raised A-frames and hang in chain lines between the top of the A-frames and the bow of the cargo tanker. Other arrangements can be used if desired. The oil lines from the A-frames can have a fixed length in system "a" or variable length in system "b". Other arrangements can be used such as a single boom mounted on a rotating table.

In system "a", the oil line transports crude oil from the pump room to the base of the A-frame(s) where there is a flexible link, e.g. a kiksan joint. The oil pipe continues up the A-frame where there is another flexible link, e.g. a kiksan joint, approximately midway on the A-frame. The flexible oil hose follows the curved surface above the top of the A-frame and forms a catenary between this and the bow (and intake coupling) of the transport tanker. The shape of the oil hose chain line and adjustment

for "chain line in water" or "chain line in air" can be adjusted by lowering or raising the top of the A-frame to a suitable level.

The A ranim in system "a"<p>g system "b" are identical in all respects. It is of eh construction with each leg hinged about halfway along its length so that one part of the A-frame can be folded back on top of the other part using hydraulic cylinders mounted at

each leg too soft to be able to lower a part onto the other. In the extended position, the A-frame can be raised or lowered., either hydraulically or by a hoist system comprising a rigid leg.. By. the top of the A-frame is provided with a curved device with a suitable radius for bending the hose and an extension to allow lateral movement of the hose.

■In system "b", the oil line transports the crude oil from the pump room to a collection pipe on deck just in front of the superstructure. Flexible pipelines (oil hoses) are preferably fed from the collecting pipe in static troughs to washers (cross heads) which are designed so that they can move in fixed tracks forward and aft in a given length of the floating storage vessel, under the influence of self-tightening devices, f .ex. self-tightening winches. The two or more flexible pipelines and associated equipment can be arranged on the floating storage vessel so as to increase the oil delivery quantity from it or to use a hose to transfer oil to the transport tanker and to transfer polluted ballast water from the transport tanker to the floating storage vessel where the ballast water is processed.

The storage vessel may be provided with a stand pipe arrangement connected to the header from the flexible hose as an alternative to the disc mounted on guides which preferably,

is fixed or fixable with a constant tensioning device and which in use connects the collecting pipe with flexible hose to the transport tanker.

Where a disc is used, this is preferably constructed and positioned so that the oil hose can be guided around the disc when fed out from the storage vessel, preferably under constant tension, during which the disc and its guide device move in or on a track.

Preferably, the guide device for the disk has the shape of a

sled. The disc is advantageously provided with a hose control device to control the movement of the hose around the disc.

For a better understanding of the invention and to show how it can be implemented, reference should be made to the design examples shown in the drawing.

Fig. 1 and 2 respectively show a schematic elevation of a floating oil storage vessel according to the invention and a perspective sketch of a section of the vessel;

fig. 3 shows a deep water mooring system and parts of an oil transfer arrangement;

fig. 4 illustrates a surface breaking modification of the mooring shown in fig. 3;

fig. 5 illustrates a shallow water underwater hose handling system from the mooring to the storage vessel;

fig. 6 illustrates a surface breaking modification of the system shown in fig. 5;

fig. 7 illustrates in greater detail parts of the mooring system in fig. 3; and

fig. 8 shows on an enlarged scale a section of the system illustrated in fig. 5 and 6.

In fig. 1 and 2 an oil storage vessel is shown which is preferably between 210,000 and 255,000 tonnes and which is provided with a collection pipe 1 which constitutes the outlet for oil from the vessel's tanks via the pump room. In system "a", an oil line H is attached to the header pipe 1 and is passed through or around a number of structures before being attached to the flexible oil hose which is passed over the top of the A frame.

In system "b", an oil line H is attached to the header 1 and a flexible hose runs in a "static" trough to a guided disc (crosshead) and then into an "active" trough to and over the A-frame aligned aft. The collecting pipe is arranged at such a height that the extension pipe in system "a" or the hose in system "b" does not need an unnecessary bend.

In system "b", the trough 3 is deep enough to accommodate any hose diameter that is used. The hose H is led out of the trough 3 and around a disk 5 which is mounted on a guide slide 7. A stroke control tongue 5 is arranged to control the hose.

out of the static trough 3 and onto the disc 5, or vice versa. The hose guide tongue can have the form of a concave shell with spindle bearings on which the hose can slide, which bearings are secured to a foot that slides in the bottom of the static trough 3. A similar hose guide tongue 4' is arranged on the other side of the disk 5

bg serves to lead the oil hose into a second hose trough designated as active trough 12.

The hose sheave can be mounted on the guide slide by means of a ball bearing arrangement 8. The diameter of the hose sheave 5 is mainly determined by the smallest bend radius that can be tolerated by the oil hose-:- The tangential edge of the sheave's circumference is placed as close as possible to the hose troughs 3 and 12 to minimize deformation and wear of the hose. When the disc is not in use, it can be mechanically attached to the vessel.

The trailer sled 7 comprises a frame mounted on wheels which are steered

of two rails overlapping the tops of the wheels. The hose guide tongues 4 and 4' are attached to the guide slide 7. Furthermore, brake shoes 6 are attached to the guide slide and serve, firstly, to prevent the hose from jumping out of the disc 5, and secondly to. to act as an emergency braking system in the event of a malfunction, e.g. loss of tension in the constant tension anchoring which will be described in the following, or breakage of the oil hose.

A self-tightening winch 10 is arranged on the vessel and is connected via a wire 10' to the guide sled 7 when the nappy delivery apparatus is in use. The winch 10 ensures that the sheave 5 is held with a largely constant tension when oil is delivered through the hose H and further provides driving force for movement of the sheave 5 along the rail passage 50 when the oil delivery via the hose H has ended and the hose is hauled back from the transport tanker. An auxiliary winch can be arranged to assist with movement of the disk 5 in the opposite direction, if necessary.

A shaft 9 passes through the disc 5 and the guide slide 7 and

serves to reduce the stress on the ball bearing 8 when pressure is exerted against the disc 5.

The brake shoes 6 can be operated by any suitable mechanism. In an exemplary embodiment, a hydraulic line 11' becomes

which is fed out from a further winch 11, used to add the brake shoes 6. The hydraulic line is not self-tightening, and the winch 11 is operated so that it cannot pull tight. Thereby, the risk of breaking the hydraulic line is prevented, which would otherwise be possible if it were exposed to tension that exceeds its strength.

The active hose trough 12 comprises concave spindle bearings at the bottom of the trough and cylindrical roller bearings along the side walls of the trough.

These are arranged to reduce the friction between the hose and the trough 12, but are not necessary in the static hose trough 3

because there is no relative movement between the hose H

and the 3 surfaces of the trough. The trough 12 extends along the vessel from the disc's 5th location and its track to the part of the vessel from which the flexible oil hose is fed out. The end of the trough 12 remote from the disk 5 is provided with either an extended hose outlet 17 at deck level (see fig. 1) or with an A-frame as the hose

passes over the vertex of (see fig. 3). Such an A-frame facilitates the routing of the hose and allows a displacement of more than 34° more

port and starboard of the floating storage vessel in relation to a transport tanker to which oil is transferred. The A-frame is designed so that half of it can be folded back on

its lower part by means of a hinge that can be locked or unlocked, by means of a hoist system with a rigid leg and the use of

two hydraulic cylinders that allow the top section to be gently lowered onto the base section. In the folded position, the equipment can be considered stowed, and maintenance can be carried out on the top section. The top of the A-frame has a radius of curvature that is adapted to the bending radius of the hose, and this part is extended so that the hose can move laterally within certain limits from the center without obstruction or wedging of the hose. This allows gearing of the transport tanker. The length of the extended, extended and locked A-frame depends on the .available

space at the stern of the ship and how much overhang the folded A-frame can be allowed to have beyond the stern of the ship. A • horizontal puller 13 (see fig. 1) above the hose and the trough is arranged in front of the bottom part of the A-frame in system "b". and serves to keep the oil hose in place in the trough 12. The mooring system must not necessarily be placed in the position shown in the drawing. The mooring equipment includes a tension release and/or manually controlled device for a mooring line, e.g. a winch and a damping roller. In cases where the hose is transferred to the transport tanker using mooring

line as control, a number of blocks can be arranged, which

. blocks are fitted with a clamp and ride along the mooring line

in use. The clamps serve ten 1 to attach the oil hose via the blocks to the mooring line. The blocks and clamps can be stored in any convenient position when not in use' and this is . for the sake of simplicity indicated by 15 in fig. 1

In the design example shown in fig. 1, the hose is passed through one or more pairs of vertical hose pullers 16 which may be located near the extended hose outlet 17. These pullers 16

can take the form of vertical rolling cylinders- like spring pressure against the hose. It is assumed that the bollards will be approximately 1.8 m high. The bollards should be made of a material capable of

to hold the hose sufficiently without damaging it. Instead of rolling cylinder pullers, concave spindles can be arranged to

provide a tighter grip on the hose and thereby prevent vertical movement.

In fig. 1, the mooring line is indicated generally at 19, and a single block and clamp 20 is shown. The blocks are lightweight constructions attached so that they can move freely on the mooring line. The clamps can be attached to the respective blocks by means of a rod with limited movement at the block. The clamps can be of an easily adaptable and adjustable type for retaining the oil hose. The material on the inside of the clamp should be such that it provides sufficient grip on the hose without

give rise to wear and tear.

Before the oil hose H runs over to the floating storage vessel,

it passes in system "b" over one or more rollers 18 which

.serves to prevent the hose from hitting the ship's rail and which prevents wear and undue stress on the hose

when significant movements occur in bad weather. Similar rollers may be located at the apex of the A-frame.

In the embodiment of an oil storage vessel shown in fig. : 3, the hose H is freely suspended from the top of the A frame above

to the transport tanker. The chain line can be adjusted so that it is completely in the air or runs through the sea.

An alternative arrangement (not shown) is that the oil transfer hose H is completely submerged between the oil storage vessel and the transport tanker. Other hose handling arrangements can also be used where this is desirable - e.g. using cranes.

The floating storage vessel also comprises precursor equipment 21 and means for allowing the lines to move freely on the surface behind the storage vessel. or hang the lines up behind the storage vessel, e.g. using a telescopic boom. The precursor can also be shot over. A cage may be provided to protect the precursor's throwing position.

One. preferred mooring system for shallow water for use in the invention is shown in fig. 5. The mooring system comprises a plinth 30' placed on the seabed, to which plinth one fluid swivel 39' is attached. This is connected with a universal joint which in turn is connected with a distance buoy 4.1',

and on top of this there is a chain boom 42'.

An oil line placed on the seabed is connected (directly or via a collecting pipe) to the shelf 30'. The shape of the distance buoy may deviate from the largely cylindrical shape shown in fig.

5. A hose guide tongue, as shown in fig. 3 and 7, can be attached to the fluid swivel in a balanced and/or supported state. The tongue ensures that the hose clears of the mooring socket and that sufficient torque arm is available to rotate the fluid swivel as required. Oil hose(s) 44'

is located in the hose guide tongue and serves to transfer oil to the storage tanks in the storage vessel.

In contrast to the deep-water system, where the underwater oil line passes up through a hose pipe in the ship and the length of hose in the water is fixed, the ground service system provides the opportunity to

raise the underwater hose 44' up along the side 60 of the ship through a "stinger" 51 to a vertically placed disk 52 which slides in rails 53 along the side of the ship 60 (see fig. 8). The position of the disc regulates the amount of hose in the water and thus allows adjustment within certain limits of the hose chain line in relation to the length of mooring chain from the storage vessel to the mooring. Rollers 54 are arranged to smooth the path of the hose against the disc

52. On the ship, the hose runs over the disc 52 and along rollers

55 to the amidships header where its coupling end connects with a quick release coupling.

One or more hoses can be handled in this way on one or

.both sides of the storage vessel. The distance buoy of the mooring

is placed sufficiently deep that it is not significantly affected by wave action and so that it provides optimal effect of the mooring chain.

In fig. 3a shows a preferred design example

a deep water mooring system for use with the invention. The mooring system comprises a plinth 30 placed on the seabed, bg a riser pipe 32 is attached to the plinth by means of a universal joint 31. An oil pipeline 33 placed on the seabed is connected via a collection pipe 34 and a flexible bottom hose 35 to an oil line 36 which is arranged on the outside or inside of the riser 32. At the top of the riser a platform 37 is arranged around a coupling 38, and on top of this a fluid swivel 39 is arranged which is connected to

"a universal joint 40. A distance buoy 41 is attached to the uriiver saddle joint 40, and a mooring chain 42 extends from 1

a chain boom, which can rotate about two axes on top of the distance buoy, to the oil storage vessel. The shape of the distance buoy may deviate from the largely cylindrical construction shown in fig. 3a. A hose guide tongue 43 is attached to the fluid swivel 39 and forms a channel through which the oil hose (e) 44 is guided. The hose guide tongue is supported or balanced so that it serves as a rocker arm for rotation of the fluid swivel. The hose serves to carry oil from the oil line 36 to the storage tanks in the storage vessel. The distance buoy is placed sufficiently deep so as not to be exposed to strong wave action.

In the design example shown in fig. 4, the spacer buoy is modified to change its characteristics and it is here extended up to the surface by means of a cylindrical member 45. This is connected above the waterline by means of a mooring 46 to the bow of the oil storage vessel or transport tanker. This modification can be used for both shallow-water and deep-water mooring.

The storage capacity of the floating storage vessel can be as large as necessary, and the aim is generally to allow a constant supply of oil from the oil wells to the floating storage vessel at the same time as the oil is delivered in batches from the floating storage vessel to the transport tankers. The transport tankers can be thought to have a capacity of between 80,000 and 100,000 tonnes, but smaller vessels, e.g. with a capacity of 60,000 tonnes, can be just as useful in certain cases.

The floating storage vessel may have a main propulsion machinery of approximately 26,000 - 28,000 hp. The vessel may be equipped with "dynamic assistance" propulsion to ease mooring forces built up by the vessel's movement or yaw movements and to keep the vessel in an optimal equilibrium position in relation to the acting forces.

Dynamic assistance differs from dynamic positioning in that its function is not to keep the ship in a fixed location relative to the seabed. Dynamic assistance will use any one or more of a large number of selected points and directions given certain environmental criteria, mooring parameters, and the vessel's draft and size.

In addition to acting as a main oil storage vessel, it can

floating storage vessels are also used for oil production facilities in cases where underwater well completion is used. Facilities for cleaning the oil prior to transport to a refinery may be included in the floating storage vessel. Use of. the storage vessel as described could possibly allow oil production without the use of a production platform with self-supporting or floating construction.

The proposed method for supplying oil from the floating storage vessel to a transport tanker shall be described below with reference to fig. 3a, b. First, the transport tanker will steer on a safe course until it is approx.

60 m from the storage vessel. The transport tanker already has

picked up the floating or discarded precursor from batch 21. Alternatively, the precursor can be transferred, at this stage using

of a telescoping boom mounted under one of the A-frames (see fig. 3b). The mooring line and file chain 19 attached to the forerunner are towed from the floating storage vessel over to the transport tanker. At this stage, in system "b", the disk 5 and the guide slide 7 together with the oil hose H will be in the front

position towards amidships as shown in fig. 3a. In system "b" will

45 m or so of hose be attached to the storage vessel. When

the mooring line. is attached, the transport tanker will stay in position approximately .45 - .75 m behind the floating storage vessel, depending on the weather conditions, the transport tanker's load and hose length, for safety reasons. As soon as a suitable distance between the floating storage vessel and the transport tanker has been achieved, the transport tanker, if its propeller steering is fine enough, will reverse and give a certain tension in the mooring line so that jolts are avoided. A for-

runner attached to the mooring line and attached to the delivery

the end of the oil hose H is then slowly pulled over to the transport tanker, taking the oil hose H with it. During this process, in the case of system "a", the hose is carefully lowered from

his stowed position into the water and limped to the transport tanker.

With system "b", the disk'5 moves from the midship area on

the floating storage vessel in the direction aft towards the stern of the storage vessel. Gradually as the oil hose is fed out from the trough

12 and are guided when suspended in the mooring line become clamps

20 fixed around its circumference at regular intervals, which clamps are carried along by their blocks which can move freely along the mooring line. When the oil hose has arrived on board the transport tanker, a quick-release coupling is inserted into a corresponding coupling on the transport tanker to thus complete the oil flow line. Where an A-frame is used,

the hose is led from the trough 12 over the A-frame which has a built-in continuation of the trough 12 and a suitable radius of curvature above its apex. The oil hose is hauled aboard the transport tanker, and a quick-releasable coupling is put in place in a corresponding coupling. The disc 5 is then tightened using the winch 10 so that the oil hose is kept in constant tension. Below these

conditions, the connection between the floating storage vessel and the transport tanker is springy and can allow an extra 4 5 m of separation movement between the vessels. Sideways drifting of a vessel in relation to the others can be tolerated from the side of the hose as long as the bow of the transport tanker does not move laterally more than 30 m to port or starboard of the storage vessel's longitudinal axis. Oil is pumped through the oil hose from the tanks in the floating storage vessel to the tanks in the transport tanker. When the transfer is finished, the above operations are carried out in reverse order so that the oil hose is pulled back from the transport tanker bg its length, which can be 300 m, is handled by movement of the disc 5 along its track in a direction away from the transport tanker.

For faster transfer of oil, the floating storage vessel is equipped with a double delivery system as shown in the drawing. The oil hose can advantageously be up to 50 or 60 cm in diameter, which allows a high oil transfer rate. Easier handling and the transport tanker's maneuverability may, however, require 30 cm cables.

Delivery of oil from the line 33 on the seabed to the oil storage vessel can take place continuously. Thus, problems associated with rapid pressure changes in the oil lines are eliminated.

A method of installing the mooring arrangement shown in fig. 3 shall be described in the following example.

After the base and the riser have been brought into place, the device consisting of the fluid swivel with flange or Graylock type coupling, hose guide tongue, the universal joint and the distance bend is connected to the riser separately or together in the following manner, as follows. use is made of either an anchored barge, a vessel with dynamic positioning or a dynamically assisted one

storage tank which will later be moored to the mooring. An extendable bridge crane is used which has a reach from the vessel of 7.5 - 9 m and which is large enough to lift and move the device individually or in parts. This crane is used to swing the parts or the device into a vertical position in a controlled manner using winches and a "tipping sled" which is mounted on guide rails and whose position is regulated by means of a winch. (This sled can be the sleds

7 shown in.fig..1 and 2). In the vertical position is maintained

the top of the spacer in a frame to avoid oscillations.

Steering wires from two self-supporting winches or other heave-compensating devices are routed from their respective disc positions on the bridge crane frame through carabiner-type fixtures that are attached to the spacer buoy. Two divers take these wires down to the diving platform at the top of the riser and secure them in predetermined positions opposite each other. The wires are tightened using self-tightening winches or other tensioning devices.

Two gates that can be opened using valves on the spacer buoy

have by this time been opened, one at the bottom of the buoy and the other near or at the top. On the buoy structure itself

is there a specially constructed buoyancy section which is not displayed by the buoyancy room which is in connection with the two ports. This special buoy section serves to keep the device vertical when in the water, but it does not keep the device afloat, i.e. it does not provide any positive buoyancy for the distance buoy or the complete device.

When the device is lowered into the water, which is done slowly to allow the water to flow in and drive air out from the main body of the buoy, it is controlled by two tension wires attached to

diving platform 37 at the top of the riser. The divers, who

has connection with the surface, controls the final immersion of the device and its connection with the riser. The flange type or Graylpck type coupling is attached. The line that was used to lower the device is slackened. It

the upper port' on the spacer buoy is closed, and a predetermined quantity of water is forced out through the lower port by pumping air into the spacer buoy by means of an air line from the surface. The lifting/lowering wire is separated from the buoy, and the two guide wires are released from the carabiner guides on the buoy. The bottom gate then closes properly. The chain is lowered and attached to the distance buoy. The oil hose is lowered and attached to the swivel. The guide wires be-

is used to lower both the chain and the hose. The guide wires are released from the diving platform. The type of vessel on the

the surface used when attaching the device determines the final method for attaching lines and marker buoys or chain and hose attachment to the mooring and hose positions in the storage vessel.

After the facility is brought into position, it will usually be maintained by a team of air divers from the floating storage vessel mooring to the shallow or deep water mooring.

When a major overhaul or replacement is necessary

parts that cannot be moved under water or the mooring must

dismantled, the device can be lifted to the surface and lifted

on board either by means of an anchored barge, a dynamically positioned auxiliary vessel or the dynamically assisted storage vessel that has been moored to the mooring. If one. anchored barge or a dynamically positioned auxiliary vessel is used, the mooring chain and oil hose are released from the storage vessel and attached to wires with marker buoys. The mooring chain hangs straight down along the side of the mooring, and the oil hose hangs in a chain line. In cases where the dynamically assisted storage vessel is to lift the device,

is it not first necessary to release the mooring chain and the oil hose from the vessel.

Two divers release the control cables attached to the diving platform. They guide the wires through the carabiner fixtures that are part of the distance buoy. The oil hose and chain are released at this point and lifted to the surface. The lifting line is attached to the top of the buoy and hung slack. The oil line on the riser is closed or will have been closed before lifting the hose, chain or device begins. The main body of the spacer buoy is filled using a water inlet valve and an air valve at the bottom, respectively. the top or near the top of the buoy. There is enough buoyancy in the specially designed buoyancy section at the top of the buoy to keep it in a vertical position. When the main body is filled with water, the two large gates are opened, one at the top and one at the bottom. The Graylock-type or flange-type coupling under the fluid swivel is loosened, and the slack in the lifting line is tightened. The device is lifted to the surface, after which water will automatically drain from the distance buoy when the device is lifted clear of the water. At the top of the lifting movement, the buoy is fed into a holding frame to avoid oscillations. The guide wires are released from the carabiner fishing trips on the buoy, and they are also released from the diving platform at the top of the riser. A marker buoy is set out to mark the position of the riser. The bridge crane that holds the device is retracted until the device is in such a position that it can be attached to the "tipping slide" which is in a semi-vertical position.-When the device is attached, the tipping slide is lowered to a horizontal position. The lifting line is released from the device. The tipping sled is then guided inwards on its rails to a place where maintenance on the device or replacement of parts can be carried out. The lifting tackle on the bridge crane can be used to move large parts of the installation.

When necessary, e.g. in case of emergency, the underwater hose will be automatically released or routed out through the bottom of the ship by means of a continuous wire hanging from a chain line, and identified by means of a surface buoy released from the side of the ship. The mooring line attached to the winch is released and passed through the cable tube and marked using the surface buoy attached to the chain by means of a line. The chain hangs in a vertical position.

In an embodiment of the invention, the distance buoy is constructed as follows. that it can be modified to form the construction shown in fig. 4. This comprises a two-part construction, the upper part of which can be changed to provide an extension to the surface as shown in fig. 4. This extension can be used as follows. The transport tanker will approach the surface extension of the device which has a floating line and a leader. The underwater hose suspended in a chain line with the connecting end at a depth of 20 m water is provided with a buoy and its leader is attached to the leader of the floating line . The forerunner will be caught from the ship's bow and brought aboard, after which it will be hauled in so that the hawser follows and can

attached using a winch or puller. The precursor for the oil hose is brought on deck, and the oil hose will follow this. The coupling end of the oil hose is attached to the quick-release coupling. After the plastering of the tanker is completed, the procedure is carried out in reverse order and the lines are released into the water.

The connection between the storage vessel and the transport tanker is, as explained above, springy and allows significant damping of the mooring forces between the vessels. This is important, especially in emergency situations such as the loss of the mooring line between the vessels. Under such conditions, the crew will have time to carry out an orderly unwinding and/or disconnection of the oil hose H.

To help the "dynamic assistance operation" and to contribute to the directional control of the storage vessel, air tubes can be used whose angles in relation to the wind can be changed. One or more rudders can be arranged on the ship's stern to help control the storage vessel's gear inclination and increase the longitudinal stability of the vessel in relation to the environmental conditions. The possibility that the ailerons can contribute with a forward force vector in the same way as a sail is foreseen and can help to reduce the forces to which the mooring and the mooring chain are exposed. The Coanda effect can also be used to improve the efficiency and power of the ailerons. Where more than one aileron is used, their angle of attack may be the same or different to provide optimum efficiency of the required power. The rudders can be adjusted manually or automatically. They can be made of canvas or metal, depending on what turns out to be best in relation to. the built-in Coanda effect and total efficiency and cost.

The rudders are preferably placed where they are from the outside of the ship

given shape will make the best use of the laminar flow of air above and around the ship. Turbulent air will be avoided as much as possible.

The Coanda effect can be exploited in three ways. The first exploitation involves shielding the front section of each rudder.

The screens on either side of the rudder can be fixed, rotatable and/or retractable. The push-out operating mechanism

or retraction of the screens may be manual or automatic, mechanically, hydraulically or electrically operated.

The second utilization of the effect directs air at high velocity along the surface of the airfoil by incorporating air nozzles suitably oriented and located, the number of which will allow coverage of the entire surface of either one or both sides of the airfoil. The design of the surroundings around the opening of each air nozzle has a critical shape that allows the most efficient distribution of the air into the laminar flow of air at high speed along the rudder. The high velocity airflows will come from a long tube-like chamber arranged in connection with the vertical axis around which the rudder rotates, i.e. its mast. The air in the tube-like chamber will be kept below a minimum of pressure that must be determined, which pressure can be maintained either naturally or by means of a fan via an air duct.

The third utilization of the effect can be achieved by means of the shape of the surface of the airfoil itself.

The control of the device, (the relative device) of the ailerons can. be done by mechanical, hydraulic or electrical means. Pressure transducers can be used to measure forces that can be analyzed mathematically to optimize the desired force effect.

In preferred embodiments, the mooring between the storage vessel and the transport tanker will consist of: (a) a file chain;

(b) a synthetic fiber rope; and

(c) wire. At the stern of the storage vessel. will there be placed a wire wine.sj . Above this there will be one winding drum. for the fiber rope. Aft of the wire winch, which may be a yielding winch, there will be a concave roller with thick ends over which the mooring line will pass. The roller is held at a given height above and aft of the wire winch by means of two arms which revolve around an axis. The arms are held in position by means of springs or hydraulically controlled jacks. The concave roller, the arms and the operating mechanism are called the damper. The damper is designed and adjusted so that it absorbs part of the cyclic shock loads in mooring the linen. This prevents extraordinary movements of the transport tanker and avoids accentuated movements of it. The fiber rope is not attached to a puller or winch, and for this reason its life is extended.

Claims (16)

Procedure for delivering oil from an offshore well to land, characterized by the steps of (a) supplying oil from the well, or from a production facility associated with the well, to a floating storage vessel moored near the well or production facility; (b) bring a transport tanker from shore to the oil storage vessel; (c) moor the transport tanker to the oil storage vessel; (d) transfer oil from the oil storage vessel to the transport tanker by means of a flexible hose which is connected at one end to the oil storage vessel's oil storage and which at its other end extends directly or via hose extensions to the transport tanker; (e) stabilizing the transfer of oil by causing the flexible hose to travel in a generally U-shaped path before leaving the oil storage vessel, which path is formed by a first hose support channel, a movable disk around which the flexible hose is guided , and a second hose support channel, which movable sheave is mounted on a steering device to move along a path extending generally along the axis of the vessel, and is attached to a device that provides constant tension so that relative movement between the oil storage vessel and the transport tanker can is recorded by means of the disk's movement along its path so as to feed out a greater or lesser length of flexible hose according to the distance at any time between the oil storage vessel and the transport tanker; (f) disconnecting the supply of oil when a predetermined quantity has been transferred to the transport tanker; and (g) bring the transport tanker back to shore. 2. Method according to claim 1, characterized in that during the transfer of oil from the floating storage vessel to the transport tanker, the positioning of at least the vessel or the tanker in relation to each other is assisted of steering rudder arranged on the vessel or tanker. 3. A storage vessel which is provided with (a) a flexible hose (H) for the delivery of oil, one end of the hose being arranged to be connected to the oil storage (1) in the vessel; and (b) a hose guide system which is designed to receive and support the flexible hose, characterized in that the hose guide system comprises (i) a movable disk (5) which is arranged so that the flexible hose can be passed over it, which disk is mounted on a control device (7) to move along a path, for example a pair of parallel rails (50), which extends mainly along the vessel's axis, preferably for a larger part of the vessel's length, which disk is preferably attached to a device that provides a constant then stretch like a self-tightening winch (10); (ii) a first hose support channel (3) which is positioned on one side of said track for supporting the flexible hose between its connection with the oil storage in the vessel and the movable disc' (5); and (iii) a second hose support channel (12) located on the opposite side of the track relative to the first hose support channel, to support the flexible hose between the movable disk (5) and an end of the vessel, whereby the flexible hose can be supported in a large set U-shaped path formed by the first hose support channel (3), the movable disc (5) and the second hose support supported channel (12) between its connection with the oil storage in the vessel and said one end of the vessel. 4. Vessel according to claim 3, characterized in that the control device for the movable disk has the form of a sled (7) which is arranged to move on said track (50). 5. Vessel according to claim 4, characterized in that the disk is supported on the slide by means of a ball bearing arrangement (8). 6. Vessel according to claim 3, 4 or 5, characterized in that hose guide tongues (4, 4') are arranged on the disc (5) and are designed to guide the flexible hose between the disc and the first and second hose-supporting channels (3, 12 ). 7. Vessel according to claim 3, 4, 5 or 6, characterized in that the flexible hose is connected at one end to a fixed manifold (1) which is in connection with the vessel's oil storage, which manifold is located next to a of the first hose support channel (3).. 8. Vessel according to one of claims 3-7, characterized in that bearing elements are arranged in the second hose-supported channel, against which bearing elements the flexible hose can slide when the movable disc moves. 9. Vessel according to one of claims 3-8, characterized in that each of the first and second hose-supported channels is designed as an elongated trough on the vessel's deck. 10. Vessel according to one of claims 3-9, characterized in that the vessel is provided with an additional .support system which the flexible hose or a hose connection connected to the flexible hose can be carried to extend from the stern of the oil storage vessel towards another vessel located behind the oil storage vessel. 11. Vessel according to claim 10, characterized by a hose dispensing device, for example several horizontal and vertical control parts, arranged to lead the hose from the hose control system to the further support system. 12. Vessel according to claim 10 or 11, characterized in that said additional support system comprises an extendable framework in the form of an A-frame which, in the extended state, is designed to hold said flexible hose above the level of the vessel's stern, preferably by projecting upwards in an acute angle over the vessel's stern. 13. A vessel according to one of claims 3 - 12, characterized in that the vessel is further provided with a mooring pipe (T) with a bell-shaped mouth, which pipe is advantageously placed in the front part of the vessel, whereby the vessel can be held in position by using a mooring. 14. Vessel according to claim 13, characterized j .in that the mooring pipe forms part of a spindle arrangement (S) which is also designed to receive a hose or hoses (44) which in use carry oil from the well to the vessel. 15. A vessel according to et.ay claims 3-14, characterized in that the vessel is also equipped with a rudder. 16. A vessel according to one of claims 3 - 15, characterized in that the vessel is further provided with means to dampen cyclic forces which tend to occur in a mooring between the vessel and a transport tanker.