JPS58180393A - Mooring structure - Google Patents

Abstract

PURPOSE:To reduce the force of floating ice, by forming the horizontal cross- section of a movable hull in the vicinity of the draft of the hull into a substantial oval shape. CONSTITUTION:A movable hull 8 has a deck 10 formed on the upper surface of the hull 8 and a draft-cross section 11 both in substantial oval shapes in a plane view. The horizontal cross-section of the hull in the vicinity of the draft thereof is formed in the shape which has a circular bow draft part 12 having its center on a mooring member guiding hole 9 and a stern draft part 13 that extends taperingly from the bow draft part to the stern. With this arrangement, the force of floating ice may be reduced in comparison with its deck area or its displacement, thereby a mooring structure with high efficiency may be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mooring structure, and in particular to a mooring structure that has a small drift ice force relative to its working deck area or displacement, and that can rotate smoothly in response to changes in the flow direction of drift ice. This is what we provide.

As demand for oil soars, offshore oil fields are being developed to great advantage. Research and development of other seabed resources is also being carried out fruitfully. Mooring structures are used as movable drilling equipment to facilitate these developments.

This type of mooring structure is, for example, a large structure with a diameter of nearly 100 m and a displacement of 30,000 to 40,000 tons, and uses a large number of mooring ropes (for example, 12) and anchors connected to the tips of the mooring ropes. It is moored at a predetermined location on the sea.

This conventional pond mooring structure has a circular or substantially circular polygonal cross section.

For this reason, when drilling in cold waters where drift ice exists, the structure has no directionality against the drift ice force (collision force of drift ice) and is not affected by the flow direction. However, on the other hand, since it has a circular cross section (3), the width of the impact of the ice floes is relatively large compared to the effective area of the deck, and the force of the ice floes increases accordingly.

The present invention was made in view of such conventional problems,
To provide a mooring structure that can make the drift ice force smaller than conventional ones compared to the deck area, can rotate smoothly even when the flow direction of the drift ice changes, and does not cause the drift ice force to increase. The purpose is to

According to the first aspect of the present invention, in a mooring structure in which a mooring cable and an anchor connected to the tip thereof are moored at a predetermined position on the sea surface to perform seabed excavation work from a deck, an excavation drill pipe and a mooring cable are inserted through the mooring structure. A mooring body is provided with a mooring body in which a vertical through hole is formed and a mooring element winding machine is installed, and a movable hull is connected to the mooring body so as to be rotatable in a horizontal direction, and the movable hull is connected to an outer wall of the mooring structure. The mooring body is inserted into a mooring body insertion hole formed at a position near the bow of the ship, and is connected to the hull.
The horizontal section (4) near the draft of the movable hull has an arcuate bow draft centered on the mooring body insertion hole, and a stern draft that tapers from the bow draft toward the stern. A mooring structure is provided which is characterized by a generally oval shape, and with such a configuration the above object is achieved.

According to the second invention, by the mooring rope and the anchor connected to the tip thereof! In a mooring structure that is moored at a predetermined position on the sea to perform seabed excavation work from a deck, a mooring body is formed with a vertical through hole through which a drill pipe for excavation and a mooring cable are inserted, and in which a mooring hoist is installed. , a movable hull that is horizontally rotatably connected to the mooring body, and the hull that forms the outer wall of the mooring structure has a substantially rotating body shape that has a vertical axis, and the mooring body has a vertical axis. and the mooring body rotatably connected to the center, and the horizontal cross section near the draft of the hull is formed by the arc-shaped bow draft formed by the mooring body and the movable hull, and the horizontal cross section near the draft of the hull is A mooring structure is provided which is characterized in that it is shaped with a narrow rlJ stern draft, and by such a configuration the above object is achieved.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIGS. 1 to 3 are diagrams showing an embodiment of a mooring structure according to the first invention.

In FIGS. 1 to 3, a plurality of (for example, 12) mooring cables 1 extend radially toward the seabed from substantially equidistant positions in the circumferential direction, and anchors 2 are connected to the tips of each mooring cable.
The mooring body 3 is moored at a predetermined position on the sea. The mooring body 3 has a generally cylindrical shape with an overhanging upper end surface, and a hoist 4 for winding in and unwinding each mooring rope 1 is installed on the upper end surface. As shown in the figure, each mooring line 1 is inserted through a vertical through hole 5 of a mooring body 3, and is stretched under the sea while being guided by a pulley 6 installed near the lower end of the through hole.

A movable hull 8 is horizontally rotatably connected to the mooring body 3 via a low friction means 7 such as a bearing 7. In the illustrated example, a mooring body insertion hole 9, which is a vertical through hole, is formed near the bow of the movable hull 8 (toward the left side in FIG. 1), and the mooring bodies 3 are connected to each other when inserted into the insertion hole. ing.

In other words, the movable hull 8 is constructed as a hull forming the outer wall of the mooring structure, and is assembled in such a manner that the mooring body is accommodated in the insertion hole 9 formed therein.

As shown in FIGS. 1 and 3, the movable hull 8 has a deck 10 formed on its upper surface and a draft cross section (cross section at the water surface W) 11, both of which have a substantially egg-shaped planar shape. . %, the draft cross section, that is, the horizontal cross section near the draft part, includes a bow draft part 12 having an arc shape (radius R) centered on the mooring body insertion hole 9, and a stern tapering from the bow draft part toward the stern. It has an oval shape with a draft part 13. In the illustrated example, the stern draft section 13 has an arc shape with a radius r smaller than the radius R of the bow draft section 120, but the shape of the stern section can be straight or any other shape. can.

The outer wall of the movable hull 8 is tilted downward and inward (7) like a normal hull.In particular, by tilting the outer wall near the bow draft 12, drift ice flowing from the bow in the direction indicated by the arrow can be prevented. Efforts are being made to reduce the impact force (drift ice force) on the ice.

In FIG. 2, a deck 1 formed on the upper surface of the movable hull 8
Reference numeral 0 designates a work deck for oil drilling or other offshore drilling, where various facilities and equipment necessary for the work are installed, such as a tower 14 on which a drilling machine (not shown) is installed. From the excavator, the excavation drill pipe 1 is passed through the vertical through hole 5 of the mooring body 3.
A pipe 5 extends toward the seabed, and a drill is installed at the tip of the pipe to perform the drilling.

According to the embodiment described above, when drift ice (for example, thickness 1771 mm) flows in the direction of arrow A as shown in Fig. 4 when moored in a sea of water and excavation work is carried out, the drift ice force is shown by the dotted chain line in Fig. 4. Although it is the same as a circular structure,
The deck area and displacement can be increased only in the portion that protrudes toward the stern. In other words, the drift ice force can be made smaller compared to the deck area or displacement, and a mooring structure with high efficiency (8) can be obtained.

In addition, the bow draft section 12 is made into an arc with a constant radius, and the width of the stern draft section is reduced to create a protruding draft cross section, so the flow of drift ice changes and moves in the direction of arrow B, as shown in Figure 4. When the mooring body 3 is the center, the movable hull 8
can rotate smoothly. That is, since there is no need to break the ice when changing direction, it is possible to change direction according to the direction of the drift ice without experiencing significant resistance even in the direction of arrow B or even against large changes in the drift ice. Note that when changing the direction of the movable hull 8, the side thrusters 16 can be used as necessary.

As shown in the figure, this side thruster is normally used for movable hull 8.
It consists of a propeller mounted under the water near the stern of the ship.

Further, since the outer wall of the movable hull 8 is inclined downwardly and inwardly at least in the area near the bow draft, the resistance value due to drift ice can be reduced. The resistance value decreases as the inclination angle θ increases, but it is actually set within the range of 25 degrees to 70 degrees.

In the above description, it is assumed that the shape of the bow draft portion 12 is a circular arc, but in reality, it may be a polygon with a large number of vertices. The details will vary depending on the roundness of the apex, the number of apexes, the hardness of the ice, etc., but the arc-shaped bow draft of the present invention may be any of the above-mentioned shapes as long as it does not interfere with implementation in view of the purpose, action, or effect of the present invention. This also includes square shapes.

Figures 5 to 10 are diagrams showing various embodiments of the second invention, and parts corresponding to the embodiments of the first invention explained with reference to Figures 1 to 4 are the same. It is displayed with a sign.

FIG. 5 and FIG. 6 are diagrams showing an embodiment of the second invention.

In this embodiment, the hull forming the outer wall of the mooring structure is formed by both the mooring body 3 and the movable hull 8.

A mooring body 3 having a vertical through hole 5 through which an excavating drill pipe 15 and a mooring cable 1 are inserted has a shape of a rotating body (approximately a conical body in the illustrated example) centered on the axis of the through hole, Its upper surface is a stationary deck 17 on the bow side. A mooring rope winding machine 4 and a tower 14 for an excavator are installed on this stationary deck.

The movable hull 8 is rotatably connected to the mooring body 3 around the center of the through hole 5 . In this example,
It is assembled by forming a hole 18 in the i-shaped bottom extension 17A of the movable hull 8 below the water surface and protruding to the bow, and inserting the mooring body 3 through the hole through the bearing 7.

As shown in FIG. 6, the horizontal cross section near the water surface W of the hull is formed by the arc-shaped bow draft section 12 formed by the mooring body 3 and the movable hull 8.
It has a generally oval shape with a narrow stern draft portion 13 projecting from the stern in a tapered manner.

In addition, the mooring body 8 has a substantially conical shape that expands upward,
The outer wall of the bow section is inclined downward and inward (angle θ).

As explained above, the mooring structures shown in FIGS. 5 and 6 differ from those shown in FIGS. 1 to 4 in that both the mooring body 3 and the movable hull 8 constitute the hull (11). and
In other respects they are substantially the same.

Therefore, according to this embodiment, when mooring in drift ice, the ice force can be made smaller compared to the deck area or displacement, as in the case described above. If you can change direction smoothly without breaking, you can always achieve the effect.

In addition, in this embodiment, when the direction changes, there is a relative rotation between the front half of the deck on the mooring body 3 and the rear half of the deck on the movable hull 8, so the equipment and equipment on the deck are designed with this in mind. need to be placed.

FIGS. 7 and 8 are diagrams showing other embodiments of the second invention.

In this embodiment, a movable hull 8 is rotatably connected above the water surface to a mooring body 3 in the shape of a rotating body, and the draft part of the movable hull 8 is made to have a substantially circular cross section, as shown in FIGS. 5 and 6. different from, and substantially the same in other respects.

Therefore, the horizontal section 11 in the vicinity of the draft has a shape in which the bow and stern parts of the vessel are separated, as shown in FIG. 8 (12).

This embodiment can also provide the same effects as the embodiments shown in FIGS. 1 to 4 or the embodiments shown in FIGS. 5 and 6.

FIG. 9 and FIG. 10 are diagrams showing still another embodiment of the second invention.

In this embodiment, a movable hull 8 is connected to a mooring body 3 at two locations above and below the water surface, and a deck is formed on the upper surface of the movable hull, and the mooring body 3 and movable hull 8
This differs from the embodiments shown in FIGS. 7 and 8 described above in that bulges 19 and 20 are formed on the bottom of the ship to suppress vertical movement, and other parts are substantially the same.

According to this embodiment, in addition to the above-mentioned effects, the movable body 8
The strength design of the connection structure, that is, the upper overhanging part 21 and the lower overhanging part 22, is relatively easy, and it is possible to effectively suppress the vertical movement of the ship during rough weather, as well as the six degrees of freedom movements such as pitching and rolling. It is possible to achieve such effects.

Although the present invention (the first invention and the second invention) has been specifically explained above by giving several examples, the scope of the present invention is not limited by these examples. , it also covers all modifications derived from the concept of the claims.

As is clear from the above description, according to the present invention, it is possible to obtain a mooring structure that has a smaller drifting ice force than the deck area or displacement, and can smoothly change direction in response to changes in the flow direction of drifting ice.

[Brief explanation of drawings]

Fig. 1 is a plan view of an embodiment of the first invention, Fig. 2 is a longitudinal sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is a line of the mooring structure in Fig. 2. Draft cross section along II[-11[, 4th
The figure is a draft cross-sectional view illustrating the condition of ice floes around a mooring structure, FIG. 5 is a vertical cross-sectional view of an embodiment of the second invention, and FIG.
The drawings are a draft sectional view of FIG. 5, FIG. 7 is a vertical sectional view of another embodiment of the second invention, FIG. 8 is a draft sectional view of FIG.
The figure is a longitudinal cross-sectional view of still another embodiment of the second invention;
0 is a draft cross-sectional view taken along line XX in FIG. 9. 1... Mooring rope, 2... Anchor, 3... Mooring body,
4... Winding machine, 5... Vertical through hole, 7... Bearing, 8... Movable hull, 9... Mooring body insertion hole, 1o
... Deck, 11... Draft cross section, 12... Bow draft, 13... Stern draft, 15... Excavation drill pipe, 17... Stationary deck, 18... Hole, ■ 9.2
o...bulge. Agent Tatsuyuki Unuma (and 2 others) ``× 1 shi531- Contest

Claims (4)

[Claims] (1) In a mooring structure that is moored at a predetermined position on the sea using a mooring line and an anchor connected to its tip and performing seabed excavation work from a deck, a vertical through hole is formed through which the excavation drill pipe and mooring line are inserted. and a mooring body on which a mooring winding machine is installed, and a movable hull rotatably connected to the mooring body in a horizontal direction, the movable hull being configured as a hull forming an outer wall of the mooring structure. At the same time, the mooring body is inserted into a mooring body insertion hole formed at a position near the bow of the ship and connected, and the horizontal cross section near the draft of the movable hull forms an arc-shaped bow centered on the mooring body insertion hole. 1. A mooring structure characterized by having a substantially oval shape having a draft portion and a stern draft portion tapering toward the stern from the bow draft portion. (2) The mooring structure according to claim (1), wherein at least a portion of the outer wall near the bow draft is inclined downwardly and inwardly. (3) In a mooring structure in which a mooring cable and an anchor connected to its tip are moored at a predetermined position on the sea surface to conduct seabed excavation work from a deck, a vertical through-hole through which the excavation drill pipe and mooring cable are inserted is provided. A mooring body is formed and on which a mooring element winding machine is installed, and a movable hull is connected to the mooring body so as to be horizontally rotatable, and the hull forming the outer wall of the mooring structure has a vertical axis centered on the mooring body. The mooring body has a substantially rotating body shape, and the movable hull is rotatably connected around the vertical axis, and the horizontal cross section near the draft of the hull is in the shape of an arc formed by the mooring body. A mooring structure having a shape having a bow draft section and a stern draft section formed by the movable hull and having a width narrower than the bow draft section. (4) The mooring structure according to claim (3), wherein at least a portion of the outer wall near the bow draft portion is inclined downwardly and inwardly.