JPS60157985A - Self-propelling type carrier vessel and method for transporting spare preparing offshore structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the transportation of prefabricated offshore structures, and in particular to the loading and unloading and transportation of drill jackets and other prefabricated offshore structures for offshore oil drilling and other purposes. relating to self-propelled marine carriers for

BACKGROUND OF THE INVENTION A drill jacket is an elongated offshore structure constructed from a plurality of tubular members with cross braces that are lowered from the ocean to the ocean floor for installation on the ocean floor. The jacket is fixed in this position and serves to support the deck unit and hydrocarbon production equipment above sea level. Deck units, typically consisting of a flat deck area with a plurality of legs extending downwardly, provide support for oil drilling and recovery equipment. These elements constitute the offshore facility.

The manufacture of prefabricated parts for such offshore equipment has heretofore required that a fabrication yard be constructed relatively close to the final desired location for the equipment.

Currently, many of these yards are located near shallow waters. When parts are made in these yards, they are loaded onto barges with shallow water. The barge will then be towed to its final location for equipment installation.

Such transport methods can be accomplished safely and reliably if the river is gentle and the towing period does not exceed 1-2 days, although weather forecasts for such short periods are usually fairly reliable. . However, even short-term towing operations can result in long delays while waiting for seas to calm. When the tugboat arrives at the installation site, the barge is moored alongside construction equipment at the site and moored in shallow water. Examples of construction equipment include cranes installed on flatbed ships.

Offshore equipment components are often more economically constructed in fully completed fabrication yards. However, due to existing favorable conditions in such fabrication yards and their number being limited by their construction costs, such fabrication yards are often located at locations remote from the final offshore facility location. However, the technical and safety hazards of long tows make it difficult for these remote yards to be advantageous over fabrication yards located near the final offshore installation site. Shallow barges, typically used for loading offshore structures in shallow water, are unstable in the open ocean due to the size and bulk of such structures and are therefore required during periods of calm weather for safe towing. and therefore risk long delays while waiting for these milder weather conditions. Due to long towing journeys, such as across oceans, there is no guarantee that good weather and calm seas will be maintained throughout the journey.

In addition, rough seas are causing damage to offshore vessels being towed by barges.
'It may also cause severe fatigue or other damage to the structure.

Fatigue stress during such transportation increases at an accelerating rate during rolling motion of the transportation structure. Barges exhibit low period rolls resulting in higher fatigue acceleration during roll than self-propelled marine carriers. Furthermore, the total fatigue stress in an offshore structure during transportation for a specified length is related to the duration of transportation. The speed of a towed barge is typically slow compared to the speed of a self-propelled marine carrier, resulting in more than twice as many fatigue cycles when an offshore structure is towed by a barge. Therefore, in rough as well as calm seas, the number and severity of fatigue stresses in an offshore structure being towed by a barge will be greater than if the offshore structure were to be transported by a self-propelled marine carrier over the same distance. , which increases the risk of damage.

In addition to loading pre-fabricated offshore structures in these fabrication yards for transport by sea, the same ship also loads pre-fabricated offshore structures that are left floating in the ocean after completion of their work for transport from one area to another. It is also desirable to have the ability to load the structure at sea. For example, jack-up drilling rigs are commonly used for exploration drilling and are therefore designed to be moved from one location to another depending on exploration needs.

In order to position the ship in the fabrication yard for the loading of prefabricated offshore structures, the main deck on which the structure is to be loaded must extend all the way to the forward or aft end of the ship, so that either the forward or aft end of the ship must be It is desired that there be no raised deck in either case. However, in order to load floating offshore structures, the main deck needs to be submerged below sea level to allow floating guidance of the offshore structure onto the main deck. To achieve this objective, the ship must have sufficient stability, such as that provided by raised decks both fore and aft, to maintain itself in a stable floating condition.

In order to achieve the above objectives, we have developed a system that is both quick and safe, thus ensuring that parts arrive on time without damage, and loading structures in fabrication yards near shallow waters or floating in deep waters. What is desired is a method of long-distance marine transportation of prefabricated offshore structures and a transport vessel therefor that provides flexibility to accommodate the loading of such structures.

OBJECTS OF THE INVENTION It is an object of the present invention to provide rapid, stable and reliable sea transport of prefabricated offshore structures from fabrication yards near shallow waters.

Another object of the present invention is to minimize the number and severity of fatigue stresses imposed on an offshore structure during its maritime transport so as to minimize the risk of damage to the offshore structure.

Yet another object of the present invention is to provide flexibility in the loading operations on the same carrier so that it can handle both the loading of offshore structures from fabrication yards near shallow waters and the loading of floating offshore structures in deep waters. Illustrative Example Referring to FIG. 1, a sea-going self-propelled vessel 10 is shown for transporting large, bulky prefabricated offshore structures 12, such as drill jackets. ing. Ship 1
0 includes a main deck 14 extending aft of the ship between its port side 16 and starboard side 18 to the stern 20 for providing suitable power equipment for propulsion and for housing and supporting offshore structures. (See Figure 3.4). Ship 10 also includes an elevated foredeck 22 on which various crew quarters, bridges, etc. are located. In this specification, the main deck is defined as the uppermost continuous deck of the ship, and the raised deck is defined as the deck higher than the main deck, and up to that height the hull is of water-sealed construction.

FIG. 2 illustrates loading a prefabricated offshore structure 12 onto a ship from a fabrication yard 24 adjacent to a shallow body of water 26. FIG. The ship 10 is operated to a point where its stern 20 meets the fabrication yard 24 and its main deck 14 is illustrated.
is at substantially the same height as the fabrication yard 24. The offshore structure 12 may be loaded onto the ship by sliding using suitable skid means, shown schematically at 25 in FIGS. 2 and 4. In FIG. 2, the offshore structure 12 has been partially slid onto the ship.

As shown in Figure 2, the depth and height of the ship is indicated by 2B).
is reasonably small to allow the vessel to operate in typically shallow waters near the fabrication yard. 28 is the depth of the main deck at the center of the ship, preferably not more than 10.7 m (gsrt). For example, the depth 28 on the main deck is 9. am(g2ft)
and the ship can take a maximum operating water load of 6, ym (22 ft).

Typical cargo handling vessels are 1/of that depth! It can be twice as wide. However, for shallow waters in which a carrier embodying the present invention is expected to operate, the inside of the ship (i.e., the maximum length of the hull in the direction parallel to the pitch axis indicated by 30 in FIG. 4) is , to give adequate stability to the ship's depth and further to give the ship greater stability than would be required to carry prefabricated offshore structures on a typical operating vessel. It should be at least 28 times as large as 28. For example, for a ship with a depth of 98111 (32ft), its width is 5t7WL (104ft).
It can be done. These ships also have a 115.9 m
ft) total length, 1000 shaft horsepower, 65.61 rL x 31
．． 7m (215ft x 104.ft) luggage deck space, 210kg/(3,0001b/ln”)
It has a maximum deck carrying capacity of 14 knots and an operating speed of 14 knots.

The main frames and bulkheads are spaced 10.20 and 40 ft apart to provide useful hull space loading conditions. Alternatively, the total length is 152.511L (500f1)
It can also extend to These ships, which have a speed of 14 knots,
It can operate more than twice as fast as a typical barge/tugboat combination towboat, thus reducing the number and severity of fatigue stresses on offshore structures.

Vessel 10 is preferably equipped with a pair of pivotable supports 32 extending aft from skid 25 for lowering the offshore structure, eg, jacket 12, into the water when completed transport to a desired location. This is accomplished in a manner well known to those skilled in the art by sliding the jacket 12 back so that the center of gravity of the jacket is transferred onto the support 32. With proper ballasting, while maintaining stability, the jacket 12 is rotated into the water through the pivoting of the support 32 and thereby lowered into the sea at the desired location. Smaller structures may be lifted using a derrick from a derrick tower barge and lowered into the water.

The jacket 12 illustrated in FIG. 1 extends over the entire area of the main deck 14. Therefore, there must be no high protruding structures on the main deck 14 during loading and transport of such jackets. In addition, no protruding structures should be present on the main deck 14 during the lowering of the jacket into the sea. On the other hand, it is mainly used for loading offshore structures such as power plants or exploration jack-up drilling rigs loaded on barges onto the main deck and floating them on the main deck for transport to another offshore location. If it is desired to submerge the deck, ships typically have surface areas at both the bow and stern ends to provide sufficient stability during the submersion of the main deck and the loading of structures thereon. I need. In the preferred embodiment shown, such water surface area is preferably provided forward of the ship by a raised deck 22.

6 and 4, at the rear of the ship 10, such a water surface area is provided, according to the invention, by one or more stabilization tanks as illustrated in pairs at 34. Each of the stabilizing tanks 34 typically has a 20 ton capacity.
It is portable so that it can be installed and removed using a crane and can be removably secured to the main deck in the manner described below. As used herein, a "stabilization tank" is defined as having a water-sealed structure to the surface when the vessel in which it is placed is submerged to a selected depth, and having a surface protrusion on the main deck for stabilizing the submersible vessel. It is defined as a part that is dimensioned to give an area. Although such tanks typically may be hollow to reduce weight and ease handling, they may also be solid tanks. tank 64
5) is sufficient to provide freeboard when the main deck 14 is submerged to the desired depth. For ships with the characteristics already mentioned, the third and fourth
Two such tanks 54 can be installed as shown in the figure, each with a height 66 of s, s m (1a t
t) and its length and width are, for example, each s, a
m (19ft). The specific dimensions and shape of such stabilization tanks can be calculated for a particular vessel using technical principles in the art.

For example, the tank 34 may be rectangular or circular in plan.

In a preferred embodiment of the present invention, as shown in FIG. 4, the ship 10 is equipped with two such portable stabilization tanks 34, one on each side, with the space between the tanks indicated at 38. leaving space.

This space 38 is 1s, s in the representative example already mentioned.
m (soft), tank 34 is installed on the ship (
18.3 (if that is preferable or necessary)
Allows loading and unloading of small structures with IJs smaller than 6 ft.

The aft end 40 of the main deck 14 as shown in FIGS.
With the stabilization tank 34 installed in the third
The water is lowered by suitable ballast tanks (some of which are shown as 42 in FIG. 2) to submerge the main deck 14 to a suitable depth as indicated by water level 41 in the figure. In this way, for example, the power generation plant 43 on board the barge 45
It is possible to float a wood-based structure such as the following on the main deck 14 for loading (R'2 or unloading). The structure is then loaded onto the main deck by raising the water.

In one example, the ship 10 is located 4.9 meters above the main deck 14.
The forward structure 44 and stabilizing tank filter 4 up to the ship's raised deck 22 have a two-part structure height of 5.5 Tn (18 ft) above the main deck. In the end, the main deck was given a diving width of about 2 feet of freeboard. Thereby, the forward structure 44 and the stabilization tank 34 functioned as stabilizing members for the ship 10. 15
For a ship having a total length of 2.5 m (500 ft) and otherwise as described above, the distance between the tank 64 and the forward structure may include a structure having a length of up to approximately 869 m (2 asrt). Enough to float and translocate.

A preferred means for installing the portable stabilization tank 34 on the main deck 14 is shown in FIGS. 5-7. A housing 46 is welded or otherwise secured to the main deck 14 and is recessed a suitable distance below the surface 48 of the main deck and reinforced by members 50. Housing 46 is configured to provide upwardly opening holes 52 and 54. Hole 52
and 54 are designed to accommodate and hang a stub point member 56 and a restraining pin 58 at the corner of each tank 64, respectively, as will be described later.

Stub point member 56 is welded or otherwise affixed to tank 64 by members 60 and 62 and is similarly shaped with a lower frusto-conical tip 64 converging to a small cross-sectional area at its lower end. is inserted into the hole 52 of. The tank 34 is guided and aligned at a desired position on the main deck 14 by the pusher so as to install the tank 34 on the main deck 14.

A member 66 having a slot 6B is welded or otherwise secured to the tank 34. The slot 68 is located directly above the hole 54 in the main deck when the tank 34 is properly aligned with the main deck and receives the shank of the hold-down pin ~58. The pin 58 is threaded at an end 72 projecting upwardly from the slot 68 to receive a locking nut 71 and a nut 70 and a washer 73. The bin 58 is formed with a T-shaped end 74 for engagement with the hole 54 in the main deck 14. Extensions 76 and 78 of housing 46 partially overhang the opening of hole 54 to form slot 80. Slot 84 engages pin shank 82 and T-shaped end 74 engages the underside of extensions 76 and 7B;
The bin 58 thereby allows the tank '54 to be secured to the main deck 14 by engaging the slots 68 and 80 with the bin shank 82 and tightening the nut 70. Such tank attachment means may be provided at each corner of the tank 54. In this way, the tank 54 is attached to the main deck 14.
The tank 64 can also be easily removed from the main deck 14 for storage.

In accordance with the present invention, to load a floating offshore structure, the stabilization tank 34 is suspended by a derrick or other suitable means to the approximate location for installation on the main deck 14; A stub point member 56 is aligned with each hole 52 and inserted therein. Thereafter, the hold-down bottles 58 are inserted into the respective slots 6B and 80 of the tank 34 and main deck 14, and the washers 73,
Fixing nuts 71 and nuts 70 are installed and tightened to securely secure the tank to the main deck. Thereafter, the ship 10 is lowered so that the main deck 14 is sunk to a suitable depth for loading the structure. In this case, the forestructure 44 and stabilization tank 34 act as freeboard and provide adequate stability to the vessel 10 during main deck 14 diving and structure loading. Thereafter, the offshore structure is floated and guided onto the main deck 14, after which the ship raises water and the main deck 14 floats above the water surface with the offshore structure on board, and is used for continuous shooting. The stabilization tank is left installed on the main deck 14 unless it becomes a nuisance. However, if it becomes necessary to load a large offshore structure in a fabrication yard near shallow water, or if the tank 34 gets in the way for other reasons, such as lowering the offshore structure into the sea, the tank 34
is removed and stored for later use.

Although the invention has been particularly described, it should be understood that many modifications may be made within the scope of the invention. For example, a raised deck can be placed toward the stern and a stabilization tank installed at the bow, allowing the main deck to extend forward of the ship and allowing offshore structures to be installed in the forward portion of the ship. As another example,
Other means for attaching tank 34 than those described herein may be used.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a ship embodying the present invention carrying a prefabricated offshore structure. FIG. 2 is a side view of a vessel loading prefabricated offshore structures from a fabrication yard near shallow water. FIG. 3 is a side view of the ship with the main deck submerged and attempting to accommodate floating structures. FIG. 4 is a plan view of FIG. 3. FIG. 5 is a plan view of a portion of the main deck with means for mounting a stabilization tank. FIG. 6 is a plan view of a portion of the tank corner showing the attachment of the stabilization tank to the main deck. FIG. 7 is a partially sectional side view showing the means for attaching the stabilization tank. 10: Self-propelled transport ship 14: Main deck 22: Elevated deck 42: Ballast tank (diving means) 34: Stabilization tank 52.54: Hole 56: Stub point member 58: Holding bottle 68.80 Varnish field 74: T-shaped Shape end 70. 71: Nut 12: Prefabricated offshore structure 24: Fabrication yard 43. 45: Floating structure drawing engraving (Schiff procedural amendment (method) with changes to the content Patented on February 26, 1985 Indication of the case of Director General Jishi W. Manabu, 1981, Patent Application No. 191892, 4f.
Name of fi Relationship with the case of a person who amends a self-contained ship and method for transporting a prefabricated offshore structure 6 Same address of the patent applicant's agent Same address Same as the notice of amendment order attached to ``1'' Showa January 29, 1960==My W
↑ε吃トカツツクス＊ＧＧＧＧＩ'='1:'-'
-＼Drawings to be amended 1 Corporate citizenship certificate and its translation 1 copy each Contents of amendment Engraving of drawings as shown in the attached sheet (no change in content)

Claims (1)

[Claims] 1) A sea-operating self-propelled vessel for loading, unloading, and transporting prefabricated offshore structures, comprising a main deck for supporting the prefabricated offshore structures, and a prefabricated offshore structure. means for submerging the main deck to a selected depth to provide flotation of the structure onto and off the main deck for loading and unloading of the offshore structure; and one end of the ship. a raised deck, at least one portable stabilization tank optionally installed on said main deck at the other end of the ship, and means for attaching said tank. 2) A ship according to claim 1, wherein the ship has a width at least 2j/2 times its depth. 3) The ship according to claim 1, wherein the ship has a depth of 1 o.7 m (+5 rt) or less. 4) A ship according to claim 1, which is equipped with means for slidingly transporting a prefabricated offshore structure on board. 5) The tank mounting means includes means for defining a first hole in the main deck for receiving a stub point member attached to the tank for alignment to install the tank on the main deck. Ships listed in section. 6) The tank attachment includes means defining a slotted second hole in the main deck for engaging and receiving a holding bottle having one end engageable with the tank for securing the tank to the main deck. A ship according to claim 5. 7) A ship according to claim 6, wherein the tank includes at least one stub point member engageable with the first hole and a restraining bottle engaged with the slotted second hole. 8) A ship according to claim 1, wherein the raised deck and the stabilization tank each have a height sufficient to provide freeboard when the main deck is submerged to a selected depth. 9) A ship according to claim 8, wherein the ship has a width at least 2 to 2 times its depth. 10) The ship according to item 9, wherein the ship has a depth of 10,7 m (gsft) or less. 11) The ship according to claim 1, wherein the raised deck is located at the forward part of the ship. 12) The ship according to claim 1, which is equipped with a pivoting support for lowering offshore structures into the sea. 16) A pair of stabilization tanks are installed at a distance from the raised deck so that offshore structures can be floated on the main deck between the raised deck and the stabilized tank pair, and the stabilized tank pair is manufactured. A ship according to claim 1, spaced apart from each other to permit loading of offshore structures from a yard through a pair of tanks.4) comprising means for slidingly transferring a prefabricated offshore structure onto the ship. A ship according to claim 13. 15) A method of submerging the main deck of a ship to a selected depth for loading or unloading structures, the method comprising providing a ship with a raised deck at one end and at least one submersion at the other end of the ship. Install two stabilization tanks, in which case each raised deck and stabilization tank shall be of sufficient height to provide freeboard when the main deck is submerged to the selected depth, and the main deck shall be A method of submerging to a selected depth, thereby floating the structure on or off the main deck. 16) The step of installing the stabilization tank includes inserting a stub point member from the tank into a first hole in the main deck;
Thereby aligning the tank for installation on the main deck, inserting one end of the holding bottle into and engaging the second hole slot, and securing the other end of the bottle to the tank. The method according to claim 15. 17) The method of claim 15, wherein the stabilization tank is removed from the main deck so that the prefabricated offshore structure is slid onto the main deck from the fabrication yard. 18) A method according to claim 17, wherein the vessel has an lj of at least 23/2 times the depth.