JPS5811290A - Riser pipe for float type platform - 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 a riser pipe for a floating platform for conveying oil produced from equipment installed on the seabed to a floating platform on the ocean.

Base 2 is used to produce oil on the seabed using equipment installed on the seabed, and to transport the oil from base 2 installed on the seabed 1 shown in Figure 1 to an offshore floating platform 3 floating on the water surface W. The method in which the and platform 3 are simply connected by a flexible pipe f4 is called the Chinese lantern shape, and has been widely adopted. As a result, the movement of the flexible pipe 4 becomes extremely unstable, and excessive force is applied.

For this reason, the flexible pipe 4, which is flexible but inherently weak in strength compared to metal pipes, is less durable and has a shorter lifespan, requiring frequent replacement, and is prone to sudden breakage. The problem was that the possibility was high.

In addition, as shown in Figure 2, if a buoy 5 is installed in the middle of the flexible soig 4 suspended from the platform 3 to serve as the intermediate point, it is better to use a flexible pipe instead of using only the flexible pipe 4 without an intermediate point. However, the movement of platform 3 at the connection point with platform 3 is greatly affected by the movement of platform 3 due to wind and waves, and excessive force and bending are applied.
In general, the closer the lower part is to the water surface W, the more the flexible pipe 4 is directly subjected to the force of the higher tidal current velocity, reducing the durability of the flexible pipe 4.

Next, as shown in Figure 3, in order to connect the offshore platform 3, which moves due to wind and waves, and the pace 2, which is fixed on the seabed 1, it is necessary to use a metal pipe, regardless of the flexible mi9iso4. A riser pipe similar to that of a drilling ship using a riser pipe 6 is also used.

This is done by pulling the suspension rope 1o of the riser pipe 6 through a pulley 8 attached to the tower 7 on the platform 3, using a hydraulically driven automatically adjustable tensioning device 9 so that the tension of the suspension rope 10 is always within a certain range. It is a method in which it is always hung,
The vertical movement of the platform 3 moored by the mooring line 11 prevents excessive tension from being applied to the riser pipe 6 or buckling due to negative tension, and prevents horizontal movement and other rotational movements. The rotary joint 12 is interposed on the 4-seat 2 side, and the live pipe 60 is made of metal but is sufficiently long and thin.
This is done through elastic deformation.

This method is used temporarily, such as on a drilling ship, and when removed to change tools, it is easy to repair or replace parts, and it does not require large-capacity tensioning equipment to disconnect even in rough weather. There is an advantage.

However, if it is to be used semi-permanently and while connected even during stormy weather, long-term durability is required, and since the movement of the platform 3 becomes extremely large during stormy weather, an automatically adjustable tensioning device can follow this. 9 has a very large capacity, making it impractical.

If this self-adjusting tensioning device 9 fails, it will be destroyed almost instantaneously due to excessive tension or buckling, so it is necessary to have a standby device that has sufficient reliability and can be activated immediately in the event of a failure. It has the disadvantage of being dependent on the dog.

Therefore, the present invention was made to solve the above-mentioned conventional problems, and it prevents excessive force from being applied to the flexible pipe that connects the seabed pace and the offshore platform, and improves its durability. The object of the present invention is to provide a riser tube for a floating platform that makes it possible to increase the

That is, the live tube for a floating platform of the present invention is
In a riser pipe that sends oil from a pace installed on the seabed to a floating platform on the ocean, an intermediate point in the water above the pace that communicates with the pace and has relatively little movement is provided, and The platform is held at a sufficient horizontal distance from an intermediate point in the water, and a trumpet-shaped guide having a sufficiently large radius of curvature is provided at the bottom of the conduit suspended via a rotary joint at the bottom of the platform. It is constructed by connecting the lower part of the conduit, through the lattice-shaped guide, and up to the intermediate point in the water with a flexible knot or ino that maintains sufficient slack. The flexible pipe is connected to a flexible pipe that connects from
It is also an effective configuration to install the guide.

The present invention will be described in detail below with reference to the drawings, in which the same parts as in the conventional example shown in Figs. 1 to 3 are indicated by the same part numbers.

First, a method of establishing 10 paces 2 on the seabed and an underwater intermediate point indicated by arrow M that communicates with pace 2 and is relatively less likely to move due to tidal currents, etc. in the water above the pace 2 is as follows. Many types can be considered depending on usage conditions and economical efficiency, and the safest type of conduit is the 4th type.
As shown in Embodiment 1 in the figures, a fixing column 13 fixed to the base 2 is provided, but this type is the most expensive, and if the height is large, problems such as easy to fall occur.

Therefore, in the case of deep water, as shown in Embodiment 2 in FIG. , there is a type that stands upright while allowing some inclination in the water to reduce the overturning moment, and the tops of the fixed column 13 in Fig. 4 and the inclined column 14 in Fig. 5 are the intermediate points in the water indicated by arrow M. It is said that

Embodiment 3 of the present invention shown in FIG. 6 is the cheapest type, and instead of the rigid pillars in Embodiments 1 and 2,
Here, too, a flexible pipe is used alone as the riser pipe 16, and an underwater buoy 17 moored to the seabed 1 by a mooring line 11 and a sinker 21 is used at the intermediate point in the water indicated by arrow M. , as the tidal current speed decreases as the water depth increases, this method may also be possible.

Next, the riser tube for a floating platform of the present invention,
The connection between the platform 3 moored to the seabed 1 by the mooring line 11 and the sinker 21 and the intermediate point indicated by the arrow M will be explained based on the third embodiment shown in FIG. This problem can be similarly applied to each of the embodiments 1 and 2 shown in FIG.

First, the lower part of a conduit 18 of sufficient length is suspended via a rotary joint 12 from the lower part of a floating platform 3 moored at a sufficient horizontal distance from an intermediate point in the water indicated by arrow M. and the intermediate point M in the water are connected by a flexible via °4 that maintains sufficient slack, and a trumpet-shaped guide 19 having a sufficiently large radius of curvature is provided at the bottom of the conduit 18, By penetrating the flexible piping f4 into the trumpet-shaped guide 19, excessive bending occurs in the flexible piping 4 at the lower part of the conduit 18 when the platform 3 and the conduit 18 move due to waves, wind, currents, etc. I try not to.

In FIG. 6, oil produced on the seabed is transported from a submarine pipeline 20 to a platform i via a conduit 18 and a rotary joint 12 by a flexible pipe f4 penetrating the base 2, an underwater intermediate point M and a trumpet-shaped guide 19. Refueled.

Here, the rotary joints 12 provided between the platform 3 and the conduit 18 in FIG. 6 and between the base 2 of the seabed 1 and the inclined column 14 in FIG. 5 may be a ball joint or a universal joint. Can be done.

In addition, if the ball joint is a single pipe, it is possible to use the inside of it as a conduit, but because it is a big pipe, etc.
It is inappropriate if the cross-sectional shape of the pipe is made uniform and the minimum radius of curvature is given.

In the case of multiple pipes or a universal joint, the flexible pipe 4 is used to pass through the center or the periphery of the pipe, and in the case of a universal joint, each pipe is passed along the axes of the two orthogonal axes of the cross bin. It is also possible to perform piping without using the flexible pipe f4 via the two arranged swivel pipe joints.

Furthermore, in the case of large water depths, in order to reduce the trouble of repair and inspection, the conduit for the rotary joint 12 on the base 2 of the seabed 1 is made of metal pipe wound in a spiral shape to reduce the slope of the small corner of the pillar. It is also possible to connect while allowing.

On the other hand, in the riser pipe for a floating platform of the present invention, there is also a flexible pipe connected to the flexible pipe 4 connected from the lower part of the pipe 18 to the intermediate point M in the water, and communicating with the platform 3 side. Vias may also be used, in which case the conduit 18 is not necessarily of a closed type, but may simply be constructed to support the flexible via 4.

Next, the following action of the flexible pipe f4 connecting the lower part of the conduit 18 and the intermediate point M in the water to the movement of the conduit 18 will be explained with reference to FIGS. 7 and 8. The shaped guide 19 damps the movement of the conduit 18 due to the movement of the platform 3, and averages out the tidal current forces acting directly on the conduit 18, so that only the movement of the lower part of the conduit 18 occurs between the lower end of the conduit 18 and the midpoint in the water. It acts on the flexible via "4" that connects with the platform 3, but since the flexible pie f4 in that part retains sufficient slack and has a U-shape with a large radius of curvature, it is suspended from the platform 3 and is used as a pendulum. The movement of the conduit 18 which acts as shown in FIG. 7 and FIG. 8 can be easily absorbed.

Moreover, since the U-shaped flexible pipe 4 is located in a sufficiently deep sea, the force of the tidal current is small, and the force acting on the flexible pipe f4 is also small.

Furthermore, a trumpet-shaped guide 19 provided at the lower part of the conduit 18
This works to prevent excessive bending at the connection between the conduit 18 and the U-shaped flexible motherboard 4.

Therefore, in the riser pipe for a floating platform of the present invention, the connecting part with the platform that moves while being exposed to the harshest conditions for flexible pipes, and the part below that which is close to the water surface and receives the force of fast currents, are the conduit. Since the flexible via is protected or supported by a trumpet-shaped guide, it has the advantage that excessive force is not applied to the flexible via and its durability is not impaired, and as a result, its reliability as a riser tube is improved. Can be done.

[Brief explanation of drawings]

Figures 1, 2, and 3 are schematic layout diagrams of different conventional examples of equipment for transmitting oil from a base on the seabed to an offshore platform, and Figures 4, 5, and 6 are different diagrams, respectively. FIG. 4 is a schematic layout diagram of a riser pipe for a floating platform in an embodiment of the present invention. Fig. 5 shows the second embodiment, Fig. 6 shows the third embodiment, and Figs. 7 and 8 are schematic layouts of main parts showing the movement of the conduit and the following action of the flexible pipe in the live pipe of Fig. 6. It is a diagram. 1... Seabed, 2... Pace, 3... Platform, 4... Flexible hoe, 11... Mooring line,
DESCRIPTION OF SYMBOLS 12... Rotating joint, 18... Conduit, 19... Trumpet-shaped guide, M... Midway point in water, W... Water surface. Figure W&1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a live pipe that transports oil from a base installed on the seabed to a floating platform on the ocean, a pipe in the water above the base that communicates with the base and has relatively little movement. a trumpet having a sufficiently large radius of curvature at the bottom of a conduit suspended via a rotary joint; For a floating platform, characterized in that a shaped guide is provided, and a flexible pipe with sufficient slack is connected from the lower part of the conduit through the inside of the brim-shaped guide to the intermediate point in the water. live tube. 2. A flexible pipe is installed inside the conduit and is connected to a flexible pipe connecting the lower part of the conduit to an intermediate point underwater, and communicates with the platform side, as claimed in claim 1. Riser tube for the floating platform described.