KR20170084374A - Offshore structure and mooring arrangement - Google Patents

Abstract

An offshore structure comprising an outer hull having a longitudinal side surface, wherein the offshore structure further includes at least one fairlead disposed adjacent the longitudinal side, and at least one of a fairlead connected to the structure, And a hook that is displaced along the hull in the longitudinal direction from the pair lead so that a displacement angle between the tangent to the outer hull at the center of the pair lead and the hook is 45 degrees or less.

Description

[0001] OFFSHORE STRUCTURE AND MOORING ARRANGEMENT [0002]

The present invention relates to an offshore structure and a mooring device.

Offshore structures may be used to produce hydrocarbon fluids from seabed or underwater wells while treating such fluids in a transportable form. In some cases, for example, if the oil pipeline is not technically and / or commercially feasible, the treated hydrocarbon fluid must be transported to the oil tanker for transportation from the offshore structure to the receiving location. In the case of natural gas, for example, it may first be liquefied to produce LNG, and the LNG thus produced may be carried by an LNG tanker, commonly referred to as a LNG carrier (LNGC).

Alternatively, the offshore structure may be used to receive the hydrocarbon fluid transported by the carrier from somewhere else, and optionally may be used to store and / or treat the thus received hydrocarbon fluid.

Natural gas is cooled with cold colorless liquid at -160 ° C (-256 ° F) to produce liquefied natural gas ("LNG"). LNG storage requires much less volume than equivalent natural gas. A considerable number of storage tanks have been developed to store cryogenic LNG. To use LNG as a power source, the LNG is converted to vapor using a revaporization process. The regasification LNG can then be distributed to various end users through pipelines.

As an advantage of LNG, LNG can be transported to the market using a ship rather than being transported by an oil pipeline. The ability to produce LNG offshore and the ability to transport LNG to the tanker allowed the development of gas storage tanks that were too far away from natural gas consumers. LNG imports using shelves have enabled the establishment of LNG storage and re-gasification facilities at land locations close to the shipping route. In addition, the industry needs to provide offshore capabilities to accommodate LNG and LPG products from carriers. As an example, WO 2006/052896 discloses a floating LNG storage and regasification unit ("FSRU").

Both types of offshore structures described above may advantageously employ a mooring arrangement to enable mooring of the carrier to the offshore structure during loading and / or unloading of the hydrocarbon fluid (s).

WO 2006/101395 discloses a mooring device provided on an offshore structure for mooring an oil tanker side by side on an offshore structure. The disclosed mooring arrangement is a structure that uses a quick release releasable hook. A rather short mooring line is used because the mooring distance is short due to the geometric configuration arranged side by side compared to land mooring such as breakwaters. A relatively short nylon rope can be used since the hook is provided with a stretchable shock absorber in the form of a hydraulic cylinder and an extendable arm. The mooring line may be curled around the guide means disposed on the oil tanker deck, and both ends of the mooring line are directly attached to the shock absorber on the offshore structure.

 US-2008/0295526 discloses a floating LNG terminal consisting of a mooring turret, an LNG storage vessel and a re-gasified vessel. The LNG carriers may be docked adjacent to the re-gasified vessel. The disclosed technique for docking an LNG carrier uses a mooring line to connect an LNG carrier to a re-gasified ship. The mooring line is arranged on the carrier and may be curled around the guide means disposed on the deck of the carrier. Both ends of the mooring line are directly attached to the re-gasified ship.

FR-2916732 discloses a floating LNG producing vessel and a carrier moored using a mooring line at a location adjacent to the LNG producing vessel. The mooring line is disposed on the carrier, and both ends of the mooring line are directly attached to the LNG production vessel.

US 2007/0289517 discloses a more sophisticated mooring system for mooring a carrier adjacent to a floating LNG re-gasification vessel. In order to maintain a predetermined distance between these vessels, a plurality of fenders are provided on the LNG regasification vessel. The carrier is attached to the mooring arm provided on the player of the regasification vessel. The coarse sling is extended from the winch on the carrier to the winch on the regasification vessel through the pulley of the mooring arm end. The winch acts as a force component to maintain a constant tension.

All of the above-mentioned offshore mooring systems are substantially different from land-based mooring systems typically comprised of breakwaters and mooring line devices. Such breakwaters are, for example, manufactured by harbor & Marine Engineering Pty Ltd. Thus, in addition to docking with land-based breakwaters, the carrier should be configured to be pivotable to each offshore mooring system.

It is an object of the present invention to provide a simple form of an offshore mooring system, generally suitable for a carrier.

SUMMARY OF THE INVENTION In a first aspect, the present invention provides a hull structure comprising an outer hull having a longitudinal side, at least one fairlead disposed adjacent to the longitudinal side, and a hull connected to the structure, And a hook displaced longitudinally from the fairlead along the hull so that a displacement angle alpha between the tangent to the outer hull at the center of the pair lead and the hook is less than or equal to 45 degrees.

In one embodiment, the offshore structure includes a plurality of fair leads and associated hooks, the fairways being spaced apart along the outer hull and configured to provide a mooring point for the carrier, each hook having an associated pair of leads And is displaced along the hull in the longitudinal direction from the pair lead. Preferably, the displacement of each hook relative to the associated fairlead is suitable to accommodate the length of the mooring line of the land-land mooring system. Thus, the offshore mooring system of the present invention is suitable for mooring a conventional tanker, and does not require additional shock absorbers or additional modifications.

In a second aspect, the present invention provides a mooring device comprising an offshore structure according to the first aspect of the invention and at least one mooring line having a pennant at one end, wherein the at least one mooring line Is attached to the hook so that the displacement angle of at least one mooring line between the tangent to the outer hull at the center of the pair of hulls and the hook is less than or equal to 45 degrees, It is possible.

The invention and its advantages will now be illustrated by way of example with reference to the accompanying drawings, in which: FIG.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic plan view of an offshore structure showing a fairlead and a hook positioned relative to a longitudinal side of the structure;
Figure 2 is a schematic plan view showing a section of the mooring deck of the offshore structure of Figure 1;
3 is a cross-sectional view of an offshore structure according to an embodiment of the present invention in which a mooring deck is disposed within an outer hull and bounded by a hull;
4 is a schematic view of a mooring device according to one embodiment of the present invention;
5A is a schematic view of a mooring device with mooring points A to P according to mooring operation of an LNGC;
Figure 5b is a schematic diagram showing the mooring arrangement of Figure 5a in accordance with the mooring operation of a further LNGC;
Figure 6a is a schematic diagram showing the mooring arrangement of Figure 5a according to the mooring operation of the LPGC;
Figure 6b is a schematic diagram showing the mooring arrangement of Figure 5a according to the mooring operation of a further LPGC; And
Figure 7 is a schematic view of a mooring device of the present invention for illustrating LNGC mooring locations relative to an offshore structure in the form of a FLNG;

Although the present invention has been described in connection with specific embodiments, it will be understood that various elements of the specific embodiments of the invention are applicable to all disclosed embodiments.

An improved mooring device for mooring a carrier to an offshore structure, usually placed in water, is proposed. This mooring arrangement is particularly suitable for use in offshore liquefied natural gas production units and / or offshore liquefied petroleum gas production units. The offshore structure may be a floating structure, and preferably it may be moored in the form of a device moving in the direction of wind blowing, so that the mooring procedure of the carrier for such an offshore structure can be facilitated.

1 shows an embodiment of an offshore structure embodying an embodiment of the present invention. In some embodiments, the offshore structure may be a floating liquefied natural gas production unit ("FLNG"). In another embodiment, the offshore structure is a liquefied petroleum gas production unit ("FLPG"). Often, offshore structures produce liquefied natural gas (LNG) as well as liquefied petroleum gas (LPG) and / or other condensate (s). For the purposes of this specification, floating units producing LNG and / or LPG will be considered as FLNG / FLPG structures. The present invention may also be embodied as an offshore structure capable of receiving and / or optionally storing and / or treating LNG or LPG or other hydrocarbon fluids from a carrier. One example of a unit for receiving, storing and regasifying LNG is a floating storage gasification unit ("FRSU").

An offshore structure may be used, for example, to allow an LNG and / or LPG carrier (LNGC and / or LPGC) to be anchored directly to the side of the structure, while loading and / or unloading hydrocarbon fluids such as LNG and / . Such an LNGC or LPGC may be moored side by side along the starboard of an offshore structure, optionally using a Yokohama floating room current to prevent contact between hulls (rigid bodies). Mooring of LNGC or LPGC using offshore structures may be achieved using mooring lines. As mooring lines develop from LNGC / LPGC to offshore structures, carriers and offshore structures can be moored next to each other for transporting hydrocarbon fluids.

In the present embodiment, the offshore structure 1 is regarded as the FLNG / FLPG structure 1, although the basic principle of the present invention is not limited to this type of offshore structure. The FLNG / FLPG structure 1 comprises an outer hull with two longitudinal sides 2. The fore and aft sections are connected to the longitudinal side 2 to form the outer perimeter of the outer hull. In a particular embodiment, the outer hull comprises two parallel longitudinal sides 2, a curved bow 12 and a stern 13, which are not necessarily essential to the invention, Section having a substantially rectangular shape. In an alternative embodiment, the stern and / or bow section may be, for example, a straight hull section between the longitudinal sides of the structure.

The FLNG / FLPG structure 1 may be moored at a mooring point in the form of a turret 17 provided, for example, Preferably, the FLNG / FLPG structure 1 can move in the wind-blowing direction about the mooring point.

At least one fairlead (3) is arranged adjacent to one longitudinal side (2). The hook 4 is connected to the structure 1 so that the displacement angle alpha between the tangent 5 of the outer hull and the hook 4 at the center of the pair lead 3 is 45 [ (3).

Selecting a displacement angle less than or equal to 45 ° allows the use of longer mooring lines compared to the case of a conventional side-by-side mooring device with considerably less lateral depth between the fairlead and the hook. In addition, since the mooring line can be formed in a length long enough to absorb impact in a conventional manner, a special hook with shock absorbing properties may not be needed, or at least the shock absorbing capacity may be reduced. Here, the conventional method refers to a land mooring system using a breakwater. Since the mooring line has a predetermined long enough length to absorb the impact due to its inherent elasticity, it is possible to exclude the additional shock absorbing device . The offshore mooring system of the present invention enables the use of a mooring line having the same predetermined length as the mooring line for land mooring as the mooring line extends past the pair lead or guide mounted in the ship. The hooks are arranged at a predetermined distance from the guide so that the total length of the mooring line is similar to the predetermined length of the mooring line for the land mooring system.

The lateral space reduction between the fairlead and the hook may be interpreted as a reduction of the space required for the mooring deck within the limits of the outer hull of the structure and because of the deck space required for the upper hydrocarbon treatment equipment, Are particularly preferred for FLNG / FLPG structures or FSRU structures. Alternatively, the space savings may be interpreted as a reduction in the need for outboard space (i.e., the space protruding out of the hull), which is considered to improve safety during approach operations of the carrier to the offshore structure.

Further, by increasing the inboard line length of the fairlead beyond the conventional mooring device, the offshore mooring device of the present invention exhibits stability comparable to the stability of the land mooring device in a more limited special environment. A displacement angle of less than 45 degrees permits a longer pennant than the known offshore mooring systems of the prior art so that the offshore mooring device can be applied to a land mooring device that provides a more secure mooring operation, So that it can be formed in a close form.

The term "pannant " as referred to herein is the mooring line or the rear end of the rope. The mooring line or the rear end of the rope is attachable to a hook on an offshore structure or to a hook on a liquefied natural gas carrier and / or a liquefied petroleum gas carrier. In a preferred embodiment, the pannel is reinforced over a predetermined length that is resistant to friction between the pannel and the respective pair of leads. Such a reinforcement treatment of the pattern includes, for example, a protective coating or a liner. The predetermined length over which the protective liner is covered is a length that exceeds the length of the protective liner applied to the terrestrial mooring system to include the displacement between the associated hook and fairlead of the present invention.

Preferably, the distance from the center of the fairlead to the hook is 10 m to 22 m. This distance is a distance that exceeds the distance of a typical off-shore mooring device, while a typical off-shore mooring device is dependent on a pontine length of 11 m and thus does not typically employ hooks over 10 m from the fairlead. In the case of side-by-side offshore mooring, the additional effective length in excess of 10 meters offshore is advantageous for shock absorption, since the length required to be connected by mooring lines from offshore structure to the carrier is relatively short. It is generally recommended that the length of the in-line of about 15 m, in other words, the distance from the center of the fairlead to the hook is preferably about 15 m.

It is preferable that the displacement angle alpha is not more than 25 degrees. At the same time, the length of the mooring line between the fairlead and the hook can be maintained at about 15 m with the lateral depth of the mooring deck less than 7 m. This range is considered an acceptable lateral space for the mooring deck on the FLSO / FLPG.

On the other hand, the displacement angle? Is preferably at least 4 degrees. By maintaining at least 4 [deg.], The mooring line extending through the fairlead to a length of approximately 15 m from the fairlead to the associated hook is displaced to a sufficient extent into the hull of the longitudinal side of the structure, Thereby enabling secure hooking work by the operator, which may be located away from the longitudinal side of the hook. In addition, by ensuring that the mooring line passing through the fairlead does not suddenly turn toward the longitudinal side as in the case where the displacement angle is less than 4 DEG, the stress applied to the mooring line is within the operating limit.

Hooks and fairways as shown in Figure 1 may also be provided on the mooring deck. Figure 2 shows a schematic plan view of an example of such a mooring deck 7 disposed within the perimeter of the outer hull 2 of the FLNG / FLPG structure 1. The pair lead 3 is arranged on the longitudinal side of the mooring deck of the outer hull 2 and the associated hook 4 is formed on the mooring deck on the longitudinal side of the outer hull 2 and on the mooring deck of the FLNG / And is disposed at an offset position from the position of the pair lead 3 in the X direction. The operator performing the pulling operation of the mooring line deployed from the LNGC / LPGC onto the mooring deck of the FLNG / FLPG for attachment to the hook 4 is located away from the longitudinal side of the outer hull 2, There is no risk of falling from the FLNG / FLPG to the sea while being protected from the components.

2, the inboard displacement of the hook 4 from the associated pair lead 3 is less than 1 m, which permits safe access to the hook provided within the ship of the outer hull 2 of the FLNG / FLPG To 5 m. In the preferred FLNG / FLPG of the present invention, the inboard displacement of the hook from the associated pair lead is 3 m. The lateral width of the mooring deck 7 may be 1 m to 7 m, preferably 1 m to 6 m.

3, the mooring deck 7 is delimited by two sides 8a, 8b of the outer hull 8 and the longitudinal sides 8c, 8b of the outer hull 8 are delimited by the two sides 8a, 8b of the outer hull 8. In some embodiments, Is open. The outer hull 8c may have a guard means 9, which may be a guard rail, a rope, a forced panel wall or a combination thereof on its open longitudinal side. Thus, the operator can be further protected from the components, thereby eliminating the risk of the operator falling to the sea.

3 showing FLNG / FLPG also shows a hook 4 arranged on the mooring deck 7 and a fairlead 3 arranged on the longitudinal side of the outer hull 8. In this embodiment, the mooring deck 7 is included in the range of the side ballast tank 10 of the FLNG / FLPG, and therefore the capacity of the FLNG / It does not depend on the presence of the mooring deck (7). In addition, the provision of a mooring deck in the recess provided in the outer hull line ensures additional safety of the operator who performs the operation of pulling the mooring line to the hook as compared to when the deck device is exposed.

By providing a mooring deck within the outer hull of the FLNG / FLPG and forming it integral with the structure, a clean hull line of FLNG / FLPG is provided and no protruding configuration is provided on the deck. Therefore, the risk of collapsing the protruding configuration of the outer hull due to collision with the LNGC / LPGC is reduced or even eliminated.

The present invention is also provided with one or more LNG / LPG storage tanks, and preferably these tanks may be implemented for FLNG / FLPG which are thermally insulated to maintain LNG or LPG at cryogenic temperatures. In some embodiments, the offshore structure is formed with a length that is at least equal to the length required to provide a sufficiently stable anchorage of the tanker alongside the side of the offshore structure, for example, a tank having a capacity of greater than about 200,000 m ³ .

A mooring line may be guided from the carrier to the fairlead 3 and the associated mooring hook 4 on the FLNG / FLPG as generally shown in Fig. The hook may be a quick release hook operable to receive the mooring line from the pair lead on the FLNG / FLPG side. The quick release hook may be combined with an electric capstan used to pull the mooring line from the LNGC / LPGC to the FLNG / FLPG structure. In some embodiments, the hook is a twin set type quick release hook having an associated electric capstan set.

For embodiments in which all mooring lines extend through the LNGC / LPGC to the FLNG / FLPG, the remote operation of the quick release hook promotes the release of the carrier from the offshore structure via a single operation in an emergency situation.

The hook may also include a load cell for monitoring the mooring line. The load cell is operable to transmit data relating to the load applied to the hook by the mooring line to the FLNG / FLPG control room to provide a real time indication and recording function of the mooring loads applied to each hook set and all hook sets. The remote release of the mooring hook may be provided by the control room. The mooring line may be released from the hook under the influence of tension.

The loading force of the mooring line is preferably kept below about 55% of the minimum breaking load. A chafing phenomenon may be caused if the length of the mooring line is increased by guiding the line through the pair lead 3 on the FLNG / FLPG to achieve the remote quick release hook (QRH). In some embodiments, the flexibility of the mooring line may be provided by a nylon tailpiece. The mooring line may be guided directly from the carrier through the fairlead 3 to the associated hook 4, as shown in Fig. The mooring line may be designed to meet the OCIMF guidelines.

In some embodiments, the flexibility of the mooring line is provided by a later-stage pannel. Exemplary materials suitable for use in the downstream pannant include, for example, polyamide and PET. As can be seen, as the length of the downstream pennant increases, the load on the line decreases and the fatigue life increases. By using a more elastic posterior material, the line lifetime of the main mooring line can be increased thanks to the reduced line load.

If the length of the mooring line between the fairlead (3) and the QRH is at least approximately 15 m, it may also be possible to ensure that the nylon pant and the connecting shackle are not close to the ship's fairlead, have. In one embodiment, the minimum safe operating load of each mooring hook may be greater than the minimum breaking load of the strongest mooring line anticipated. In some embodiments, the load on the operating mooring line may not exceed 2.5 times the winch brake holding capacity or 2500 KN. The maximum mooring load may not exceed 2.5 times the minimum breaking line load or 3125 KN. The capstan barrel may be provided at a suitable height to permit safe handling of the messenger line. The QRH assembly may be electrically isolated from the platform deck. This isolation process may provide an electrical resistance of at least about 10 ⁶ ohms.

The QRH may be placed on the FLNG / FLPG. The mooring line may be led from the carrier to the fairleads 3 and QRH on the FLNG / FLPG. In order to prevent chaffing of the mooring line, the edge of the deck at the front of the mooring hook may be formed in a circular shape. In some embodiments, at least one pair lead is connected to the structure. Such at least one fairy may be connected to a structure adjacent to the longitudinal side.

The fairlead may be an open fairlear with the top open. However, in order to prevent the mooring line from being lifted out of the fairlead, for example, a so-called Panama type closed fairlead may be preferred. The mooring line may pass through the opening of the pair lead. In particular, the Panama Design's closed fairways are designed to accommodate the LNGC / LPGC mooring line while delivering the mooring line in the longitudinal side lane to the quick release mooring hook located on the mooring deck of the FLNG / FLPG. It may be fitted on the side surface. The specification of the fairlead preferably matches the safe operating load (SWL) of the quick release hook set. As an example, considering the minimum breaking stress (MBL) of the LNGC / LPGC mooring line, the SWL is 125 t.

In some embodiments, a single fairy may provide only a single mooring line and a hook.

The fairy may be mounted adjacent to the longitudinal side of the FLNG / FLPG and also in line with the streamlined side of the longitudinal side. It is preferred that these fairings do not have protrusions or sharp edges onboard or outboard sides to prevent further wear of the mooring line that occurs as the mooring line passes through the fairlead.

A closed fairyard of Panama design typically has a base that is attachable to an offshore structure. The fairy is formed in the form of a ring extending upwardly from the base and having an annular hole in its center. The annular hole is generally oval. The base is typically 1300 mm long and 560 mm wide. The distance from the base to the center of the annular hole is typically 505 mm and the height of the pair lead is 930 mm. The annular hole is typically 450 mm high, 600 mm long, and approximately 225 mm in radius. The inner radius of the fairlead is large enough to effect the stress reduction applied to the mooring line.

The friction ladder or material may be formed in a line in the pair lead. The friction reducer may be a Nylacast ^TM protective insert for reducing chaffing of the synthetic mooring line pannel. The Nylacast ^TM material is a synthetic material containing a lubricant that minimizes chaffing damage to the fairlead LNGC / LPGC mooring pennants.

To detect the approach speed of the carrier; To monitor the mooring line load through the stress gauges of QRH; And / or a pressure monitoring system may be provided in the offshore structure to serve as a pressure monitoring system for the air block room. Data from these surveillance systems may be collected and displayed centrally in the control room.

FIG. 4 shows an embodiment of FLNG / FLPG according to the present invention. The FLNG / FLPG 1 includes a plurality of pairs of leads 3 and an associated hook 4. In the illustrated embodiment, the fairleads 3 are spaced along the outer hull 8 of the FLNG / FLPG and provide a mooring point for the liquefied natural gas carrier 11 and / or the liquefied petroleum gas carrier 11 . For ease of reference, fairies may be numbered from bow to stern using alphabet letters A to P in this embodiment. A mooring deck may be formed along the starboard side of the hull to accommodate the side fair lid 3 and the mooring hook 4, which are generally constructed as shown in Figure 4 (FLNG / ). FLNG / FLPG mooring devices may typically include a mooring line developed from LNGC / LPGC. A typical mooring line may include a headline, a sternline, a breastline, and a springline.

The FLNG / FLPG may include a loading / unloading connection for transferring the hydrocarbon fluid (s). Such connections may include a manifold of one or more transfer arms. Such manifolds are known, and typically the LNG transfer manifold consists of three arms, the middle arm being a steam arm. The LPG transfer manifold may also include one or more transfer arms. Typically, the vapor transfer lines may be combined with other arms to provide no separate vapor arms. Such a transfer arm may be a Chiksan unloading arm commercially available from FMC Energy System. Typically, the LNG / LPG transport equipment includes a power pack, a control unit, a piping and piping manifold, a piping guard from mechanical damage, a vessel / coastal access gangway with operating room, a gas detector, (ERS), a quick connect / disconnect unit (QCDC), a surveillance system and / or a drainage system.

Assuming the mooring on the turret located at the bow, the loading / unloading manifold is located at a suitable position between the middle and rear portions of the offshore structure, for safety reasons, to be placed as far back as possible from the processing equipment and turret . Ideally, however, the manifold is also located further away from the crew chamber on the offshore structure, as compared to the case of a conventional carrier.

For purposes of example of the present invention, it is assumed that the transport manifold includes an LPG manifold as well as an LNG transport manifold. In the example below, it is assumed that the LNG steam arm is placed on the FLNG / FLPG at a distance of 185 m from the stern of the structure and the LPG connection is located about 10 m behind the LNG steam arm. Thus, an LNGC / LPGC manifold offset interval of 25 m (based on the middle of the carrier) is accommodated. The location of the fairlead, which is considered to be the location of the LNG / LPG steam arm, is to accommodate a mooring line from LNGC with a capacity of 75,000 m ³ to 217,000 m ³ and LPGC with a capacity of 74,000 m ³ to 84,000 m ³ . May be set.

Referring to Figures 5A, 5B, 6A and 6B, in certain embodiments of the present invention, the position of the mooring point, relative to the LNG steam arm 6, as indicated by the fairlead 3, (A to P) are as shown in Table 1.

lead Distance to LNG steam arm Number of leads / hooks The direction of the lead to the hook Distance from lead to hook A 175.0 double Forward 15m B 155.0 double Forward 15m C 140.0 double Forward 15m D 120.0 double Forward 15m E 100.0 double Forward 15m F 70.0 double Towards the steam 15m G 40.0 double Towards the steam 15m H 20.0 double Towards the steam 15m I -30.0 double Towards the steam 15m J -55.0 double Towards the steam 15m K -80.0 double Towards the steam 15m L -110.0 double Towards the steam 15m M -125.0 double Towards the steam 15m N -145.0 double On board 15m O -155.0 Three times On board 15m P -175.0 Three times On board 15m

Positive values of the distance between the mooring points (A to P) and the LNG vapor manifold in Table 1 indicate that the position of the mooring leads is forward of the LNG vapor arms (A to H), and negative values indicate that the position of the mooring leads And the rear of the LNG steam arms (I to P).

In the embodiment of Table 1, a plurality of pair leads are accommodated in respective lead positions. In the lead positions A to N, two pairs of leads are housed and three pairs of leads are housed in the lead positions O and P, respectively. The direction of the leads to the hook is indicated in the direction in which the mooring line passes through the fairlead and leads to the associated hook set. The three sets of leads (N, O, P) located within the acceptance / service area of the FLNG / FLPG are guided into the ship of the FLNG / FLPG towards the associated set of hooks. In an embodiment as described in Table 1, the distance between the hooks associated with the pair leads is 15 meters. According to this distance, the total length of the LNGC / LPGC mooring line is combined with the nylon / polyester pannel so that the length of the LNGC / LPGC mooring line is sufficient to absorb the peak mooring load when the sea level reaches 3 m The line can be expanded.

In some embodiments, the length of the downstream pennant is 11 m. However, in some embodiments, the length of the rear end pennant is preferably 22 m.

According to the embodiment of the present invention in which the distance from the lead to the hook is 15 m and the length of the pannel is 22 m, according to the distance from the lead to the hook of 15 m, a mooring pennant of 22 m is placed on the lead on the FLNG / FLPG side To prevent damage due to collision of LNGC / LPGC composite HMPE and wire mooring line alternately arranged on the same lead. In addition, the distance from the lead to the hook of 15 m provides increased mooring line length (length from the LNGC / LPGC winch to the FLNG / FLPG hook) as compared to the conventional case. For typical coastal terminal marinas, the length of the mooring line is typically 35m to 50m, and this typical mooring line length is not valid in a typical side-by-side marine mooring configuration.

In order to maximize the length of the in-line mooring line of the fairlead, the distance from the fairlead to the associated hook is preferably as long as possible.

As shown in Figs. 5A, 5B, 6A and 6B, the mooring device is also capable of moving the corresponding manifold on the FLNG / FLPG structure and the loading / unloading manifold of the carrier on the FLNG / FLPG structure even when the manifold of the carrier is not located on the centerline of the carrier So that carriers of various types and sizes can be moored side by side.

5A and 5B are FLNG mooring layouts using the mooring points A to P. As shown in the figure, the FLNG is a 290 m long LNGC 11 having a loading / unloading manifold at different positions with respect to the center line of the carrier ) Can be anchored side by side. 5A, the manifold 16 is located on the center line c of the carrier, whereas in Fig. 5B the manifold 16 is located about 15 m in front of the centerline c of the carrier. In both cases, good alignment between the manifold 16 of the carrier and the target indicated by the LNG vapor arms 6 is achievable.

Experimental results using the Optimoor analysis tool show that even if the LNG manifold on the 290m long LNGC is displaced 24m forward of the centerline of the carrier, the carrier can be safely anchored next to the mooring device. In this case, the mooring point P is employed. Although the mooring device may also accommodate a carrier provided with the LNG manifold behind the centerline of the carrier, in the industrial sector this is extremely rare, because the manifold requires to be located as far as possible from the crew chamber Lt; / RTI >

6A and 6B, the offshore structure 1 is shown in a mooring configuration with mooring points A to P, with LPGCs of length 203 m and 214 m respectively moored side by side . The LPG loading / unloading manifold 16 'of the carrier is located relatively close to the centerline c of the carrier, but the target manifold 6' on the offshore structure 1, which serves as the LPG connection, 'Are disposed at a distance of about 10 m behind the LNG steam arm 6. Likewise, excellent alignment is achievable.

Thus, the offshore structure 1 that accommodates the proposed mooring arrangement is configured to accommodate LNGCs and / or LPGCs of considerably different sizes and shapes, including manifold offset spacing.

In certain embodiments, the FLNG / FLPG according to the present invention may comprise at least three spring fair leads and associated hook sets. Therefore, the mooring plan of FLNG / FLPG includes spring expansion from LNGC / LPGC. Where weather conditions are to be taken into account, the LNGC / LPGC will develop two springs from the main deck and one spring from the other deck, taking into account the inevitable requirements for corresponding spring leads and hook sets on the FLNG / FLPG. It is possible.

FIG. 7 shows another example FLNG / FLPG 1 that is fixed to the turret 17 at the bow 12. A mooring deck (7) is provided on the starboard side of the outer hull of the FLNG / FLPG. As shown generally in Fig. 7, the mooring deck extends approximately 380 m forward from the stern of the FLNG / FLPG 1 and is located 14.5 m above the active water surface. In some embodiments, the FLNG / FLPG (1) allows secure access between the rear of the mooring hook set and the front and rear bulkheads, and while the operator pulls the mooring line to the FLNG / FLPG using, for example, Mooring decks with a width of 1 m to 6 m may be included to allow sufficient space to collect the mooring messenger. In one embodiment, the FLNG / FLPG may include a mooring deck having a width of 4 m. As shown further in Fig. 7, a plurality of rooms < Desc / Clms Page number 10 > between the FLNG / FLPG and the LNGC / LPGC are provided between the FLNG / FLPG and the LNGC / LPGC to prevent damages that occur while the carriers 11 are moored and moored next to the offshore structure 1 (22).

For example, in the case of FLNG / FLPG, offshore structures may contain LNG / LPG storage tanks and may contain LNG / LPG vaporization equipment and / or liquefaction equipment, gas treatment equipment (eg, , Mercury removal equipment, etc.), intake separator and slug trapping equipment, agglomerate stabilization equipment, etc., can be placed on top of the FLNG / FLPG, and LNG / LPG can be safely and safely placed next to the FLNG / FLPG To be anchored. Further, it is possible to consider the provision of equipment for seizing carbon (carbon dioxide) and then combustion equipment for trapping the generated gas and / or treatment of the separated CO ₂ from the hydrocarbon feed.

In the case of FSRU, the offshore structures may accommodate other options such as regeneration, heating value control and metering equipment and, for example, as described in WO 2006/052896, the entire contents of which is incorporated by reference.

The external turret system 17 may be a preferred option for anchoring an offshore structure at normal water depths exceeding 30 m. An external turret may be desirable for the Yoke Mooring System (YMS), although it may depend on depth and may require a complete riser configuration as a concept of selection. An arrangement of a bimodal riser arrangement may be feasible.

Another mooring system of the FLNG / FLPG of the present invention may be a device that moves as the wind blows to achieve a sufficiently high connection limit for the anchoring operation of the LNGC / LPGC. Another mooring system and a high pressure gas discharge line may be disposed at the front end of the FLNG / FLPG of the present invention. After the positioning of the FLNG / FLPG of the present invention, an evaluation of the technical feasibility of another mooring system including, for example, an external turret system, an internal turret system, a yawmilling system (YMS) . An example YMS may include, for example, a jacket (the jacket may include a tubular structure with four legs, which may be fixed to the seabed via four or more piles, driven through an edge tubular body, The mooring head (the mooring head may be disposed on top of the jacket and may be configured to be freely rotatable, and the mooring head may also support an oil pipeline and equipment including the plying laminate), a yoke A permanent ballast tank may form part of the yoke structure to provide the requirements of the mooring leg), a mooring leg (the mooring leg may be a single And may include a tubular forcing member connected to the adjacent structure through the connecting portion, Mooring structures on the FLNG / FLPG (mooring structures on the FLNG / FLPG may be FLNG / FLPG mooring structures on the FLNG / FLPG) And this structure may also protrude from the bow of the ship to provide a clearance for the yoke and elevating means may be provided for handling one or more jumper hoses) , And gas delivery may be performed through one or more, generally two, 16 "flexible jumper hoses that may provide a capacity of 2 x 100%.

Another mooring system including YMS may include a gas swivel for transferring the discharge gas from the FLNG / FLPG moving in the wind direction to the fixed oil line riser. An " N + 1 " arrangement of fluid delivery systems may be obtained through additional annular swivel modules, although an in-line swivel is expected to provide sufficient reliability (typically 20 years MTTF). While the inline swivel may be used as the main operating element, the annular module may provide a complementary function. The in-line swivel can be replaced in the event of a fault, in which case the off-gas may be moved through the annular swivel path.

In some embodiments, for example, the height from the surface of the upper surface on which the mooring equipment, such as a quick release hook (QRH), is disposed, is such that the angle of the mooring line extending from the mooring equipment to the liquefied natural gas carrier on the water is approximately 30 ≪ / RTI >

The centerline of the cargo arm may be arranged to achieve the maximum degree of protection for all types of general LNG / LPGC / LPGCs.

Although three loading arms of the concept as described above are technically acceptable, the four loading arms may represent an overfeeding concept. Overfilling may increase integrity and / or reliability levels. An extra cargo arm may be used as a day to day concept. This may ensure proper functioning of the equipment. The installation of one or more extra cargo arms may increase the nominal loading capacity of the entire LNG / LPG. The shape of the FLNG / FLPG may be determined in consideration of a plurality of weather conditions.

The transfer of LNG / LPG between LNGC / LPGC and FLNG / FLPG may be based on conventional rigid arms, which are currently used for land-based terminals for ship-to-shore LNG / LPG transport. A guide-wire system may be used to guide the loading arm to the ship manifold, so that safe and reliable connection and disengagement movements can be made along the course for transport between float.

The appropriate overall length of the offshore structure to which the present invention is applied may be a length to provide for the storage and / or treatment of a hydrocarbon fluid, such as LNG / LPG, as described herein, Specifically at least about 200 m, more specifically at least about 300 m, generally not more than about 1000 m, more specifically not more than about 750 m, and more specifically not more than about 500 m.

The appropriate width of the offshore structure may be wide enough to provide for the storage and / or treatment of hydrocarbon fluids, such as LNG / LPG, as described in the present invention, and is generally at least about 20 m, More specifically at least about 40 m, and generally not more than about 300 m, more specifically not more than about 200 m, and more specifically not more than about 100 m.

A suitable draft of an offshore structure may be a draft to provide for the storage and / or treatment of hydrocarbon fluids, such as LNG / LPG, as described herein, generally at least about 5 m, At least about 7 m, more specifically at least about 10 m, and generally not more than about 25 m, and preferably not more than about 20 m. In one embodiment, the draft may be approximately 17.6 m.

The ratio of the proper length to the depth of the offshore structure may be a ratio of length to depth to provide storage and / or treatment of the LNG / LPG as described in the present invention and is generally at least about 5, About 7, more specifically at least about 10, generally not more than about 20, in particular not more than about 18, and more specifically not more than about 15.

In the case of a yoke mortising system ("YMS"), it may be an example of another mooring system of an offshore structure, since the water depth at the offshore location may be approximately 15 m to approximately 30 m have. It can be ensured that this other mooring system used only when the maximum marine conditions have been met can meet the maximum marine conditions.

According to one example of the present invention, the approach of the LNGC / LPGC to the FLNG / FLPG is such that both the FLNG / FLPG and the LNGC / LPGC provide information about the predominant weather conditions and conditions for approximately 12 hours prior to the estimated arrival time ≪ / RTI > For example, preparations such as LNG / LPG arm, mooring equipment, current inspection and selection of LNGC / LPGC approach are performed for approximately 1 hour before ETA, and LNGC / LPGC is approximately 2 to 3 Harry arrives at a negotiated entry point, usually at a forward speed of 4 knots; The anchoring master is pulled up to the ship and ready for connection to the tugboat, and the LNGC / LPGC is moved toward one position on the starboard side of the FLNG / FLPG and is completely in parallel with the FLNG / FLPG at a distance of about 100 m After stopping, the LNGC / LPGC is moved sideways at a predetermined approach speed towards the FLNG / FLPG while monitoring the applied thrust / force attraction; If control of the LNGC / LPGC position and forward movement is difficult, the approach should be stopped and pneumatic equipment may be used to launch the IM line from the FLNG / FLPG. It can be expected that the mooring line will pass after touching the room current.

Currently, the critical digging threshold value Hs for anchoring the LNGC / LPGC alongside the FLNG / FLPG may be regarded as approximately 2.0 m to approximately 2.5 m and may be considered to be moored next to the FLNG / FLPG of the present invention It may be regarded as approximately 2.5 m to approximately 3.0 m.

The starting operation of one example is done in a substantially reverse order of the example approach procedure. At the beginning of the actual start operation, the ESD link system with the integral system maintenance radio link needed for a secure start is disconnected. The LNGC / LPGC enters the ready state for starting the start operation. Thereafter, the mooring lines are separated and this separation may be made one by one according to the prevailing weather conditions and the final operating procedure.

According to one exemplary starting operation, the player of the LNGC / LPGC may be moved to separate from the FLNG / FLPG using the tugboat or the carrier thrust device of the carrier, in combination with wind / wave / current conditions. When the hulls are separated from each other, the LNGC / LPGC is separated and moved using its main propulsion system and the tug is separated.

Mooring of the LNGC / LPGC may occur at the foremost and last locations. The mooring device of the present invention may be used with a bristle line and a spring line.

As can be clearly understood from the foregoing description, in an offshore structure having a mooring device as described above, carriers of different sizes and shapes can effectively be pierced in most sea conditions, where the critical wave height is 2.5 m or 3.0 m have.

This mooring device also mimics a land mooring device; In other words, the mooring line deployed from the carrier shows a planar layout similar to that provided on land terminals.

Various modifications and variations of the present invention are possible, and specific embodiments as illustrated in the figures are described in detail as described above. The drawings and detailed description are not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined in the appended claims, Equivalents, and variations.

Claims (1)

An offshore structure characterized by the description of the present invention.

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