JP2005121077A - Submarine pipe laying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a submarine pipe laying method capable of efficiently executing the laying work without using anchors even in the very deep sea area, with respect to the submarine pipe laying method by a submarine towing method. <P>SOLUTION: In this submarine pipe towing method for laying pipe bodies connected on land or at a long pipe manufacturing yard on a salvage barge, at the bottom of the sea by towing out the pipe bodies to a sea side by a tug-boat positioned at the offing through launching equipment, the DPS tug-boat 4 equipped with GPS 12 and a propelling machinery 11 is placed at the offing, and moved along a laying line, while measuring a position of the tug-boat by the GPS 12 and keeping the DPS tug-boat 4 at a fixed position by the propelling machinery 11, to lay the submarine pipes such as intake pipes 2 while towing the pipes without anchoring the DPS tug-boat 4. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a remote island water supply method and a construction method for constructing a submarine pipe for transporting oil and gas. In particular, the construction of a submarine pipe is advantageous when laying a submarine pipe at a large depth, such as a deep-sea water intake pipe. Concerning construction method.

  Typical examples of conventional methods for laying submarine pipes are (1) laying method, (2) floating towing method, and (3) submarine towing method. Each of these methods is introduced in “Nippon Steel Submarine Piping” issued by Nippon Steel Corporation (pages 16 to 25). The outline is as follows.

(1) Laying ship method This is a construction method in which a pipe is moved by moving a laying ship while welding a short pipe on the laying ship. It is suitable for laying long submarine piping of several tens to several hundred km, and has a lot of experience in oil and gas submarine piping. In order to increase work efficiency, multiple stages of welding, inspection, anticorrosion, etc. are used, and in order to obtain an appropriate laying curve in the water, a dedicated laying ship equipped with a tensioner and stinger is used. In addition, a fleet with a normal pipe transport ship, tug boat, and anchor boat is formed.

(2) Floating tow method Long pipes connected by a number of short pipes are joined on land or on a marine carrier on one side of the laying line, and then levitated on the opposite shore or offshore towing on the surface of the water. After that, it is an economical method for laying a relatively small scale (several kilometers) submarine pipe that is submerged in the bottom of the water.

(3) Submarine towing method A long-boat production yard is used as a long pipe anchored on land or at sea, and a 10-20 m short pipe is welded and joined in this long pipe production yard to make a long pipe, or produced in an adjacent yard. This is a construction method in which the long pipe is towed and laid on the seabed with a winch on the opposite shore or by a dredger winch placed offshore through a launching facility with guide rollers.

  This submarine tow method can be constructed efficiently with relatively simple equipment, and because it is towed along the bottom of the sea, it is relatively unaffected by meteorological conditions and the traffic of ships such as in the channel can be reduced. There is a feature that can be applied to frequent places.

  In addition, there is an invention filed by the applicant in Japanese Patent Application Laid-Open No. 2003-194259 (Japanese Patent Application No. 2001-391065) regarding a method of laying a deep-sea water intake pipe. The present invention belongs to the seabed towing method, and as shown in FIG. 4, the intake pipe 2 elongated in the long pipe production yard 1 on the ground is moved on the roller 3 and launched to the seabed. Then, the towline 5 attached to the tip of the intake pipe is wound up by the winch 15 installed on the offshore work ship 14 and the intake pipe is laid down to deep water at a deep ocean water intake depth (200 m or deeper). In addition, a frame 6 is provided to hold the tube tip 2a at a predetermined height from the sea bottom surface 7, and the water stop lid 10 temporarily attached to the tube tip 2a is removed by remote control.

At the time of laying the intake pipe, the anchor wire 15 is lowered from the work ship 14 to the sea bottom surface 7 and the work ship 14 is stopped at a fixed position for laying work.
Booklet published by Nippon Steel Co., Ltd. “Nippon Steel Submarine Piping” (pages 16-25) JP 2003-194259 A

  In the prior art, (1) the laying method is not efficient because a short pipe of about 12 m or 24 m is laid while being welded on the laying ship, and if a large number of welding stages are provided to increase efficiency, the equipment cost is low. There was a problem that would be expensive. Moreover, it is necessary to assemble a fleet such as a tug boat and an anchor boat in addition to the laying ship, which is a large-scale work organization.

 (2) The floating towing method is effective for field work because it joins the long pipes, but it is necessary to restrict the traffic of the ship in the construction, and the route crosses the route where there are many traffic of the ship. There were issues that could not be applied. In laying work, relatively calm weather and sea conditions are required.

 (3) The submarine towing method is a relatively advantageous method without the disadvantages described above. However, when laying using a dredger placed offshore, there is a problem in maintaining the position of the dredger if the laying water depth is deep. . In other words, in the conventional method of drawing a long pipe with a dredger, as shown in FIG. 4, the pipe body is towed and laid by winding a towing line fed from a winch mounted on a dredger anchored with a dredger on the seabed. Therefore, if the water depth is deep, the anchor will not be effective and the hull position will not be maintained accurately, and the reaction force when the piercing force is applied to the pipe will be insufficient or the catenary shape of the anchor wire will change. Because of the movement, there is a problem that it is difficult to control the tension applied to the tube body.

  In addition, even when the laying water depth is not so deep, if the laying extension distance becomes long, the weight of the towline (wire rope) will increase, and the frictional resistance with the sea floor will increase, so a large pulling force will be required. There is a problem of frequently changing anchors of dredgers in order to provide a large-scale winch and anchor equipment or to shorten the laying extension distance.

An object of the present invention is to provide a submarine pipe laying method that can be efficiently constructed even in a large deep water area without using an anchor in a submarine pipe laying method by a submarine towing method.

  In order to achieve the above object, the present invention is configured as follows.

  The first invention relates to a submarine pipe towing method in which a pipe added in a long pipe production yard on land or on a base boat is laid out on the sea floor by drawing out to the sea side by a dredger placed offshore through a launching facility. A DPS dredger equipped with GPS and a propulsion device is placed offshore, and the dredger position is held by the propulsion device while moving the dredger position in place while positioning the dredger position with the GPS. It is characterized by laying and laying a pipe.

  According to a second invention, in the first invention, a towline fed from a winch provided at the stern of a DPS dredger equipped with GPS and a propulsion device is connected to the tip of the tubular body, and the DPS dredger is connected to an offshore laying line. It is characterized by holding the position in the same place and rolling out the pipe body by a winch operation.

  According to a third invention, in the first invention, a towline connected to the stern of a DPS tow ship equipped with GPS and a propulsion device is connected to the tip of the tubular body, and the tow ship is moved along an offshore laying line. It is characterized by rolling out the tube.

The fourth invention is the first invention, in which the DPS dredger is connected to the tip of the tubular body while unwinding the DPS dredger offshore with the winch provided at the stern of the DPS dredger equipped with GPS and propulsion equipment offshore. The pipe body is laid and extended by repeatedly rolling out the pipe body by a winch operation while moving along the laying line, and stopping at a predetermined position and holding the position.

  According to the present invention, in a submarine pipe towing method, a pipe added in a long pipe production yard on land or on a base boat is drawn out to the sea side by a dredger placed offshore via a launching facility and laid on the seabed. A DPS dredger equipped with a water depth machine is placed offshore and the dredger is held in place with a propulsion unit while measuring the dredger position with GPS, or the submarine pipe is spread and laid while moving along the laying line. is there. Therefore, since the dredger is not anchored, the anchor does not work well in the deep waters, which has been a problem with the conventional laying method, and the accuracy of the hull position is deteriorated. It is possible to solve problems such as that the reaction force is insufficient, and that the catenary shape of the anchor wire changes and the hull moves, making it difficult to control the tension applied to the tube.

  In addition, according to the second invention, the DPS dredger is held at a predetermined position offshore by using a GSP and a propulsion device, and the tubular body is operated by the winch equipped on the stern. It can be performed with good responsiveness.

  According to the third invention, the length of the towline can be shortened because the towline having the tube connected to the tip thereof may be directly connected to the DPS dredger. Therefore, since a long towline is not used, the towline material can be saved and the frictional resistance of the towline at the time of laying a submarine pipe can be significantly reduced.

Further, according to the fourth aspect of the present invention, while unwinding the towing line of the pipe wound around the winch of the DPS dredger, the DPS dredger is moved a distance in the direction of the laying line, stopped at a predetermined position, measured by GPS, and the propulsion unit The length of the towing line can be made relatively short because the laying method repeats the work of rolling out and laying the pipe body by the winch operation while maintaining the position. Thus, when the laying extension is applied to a submarine pipe laying over a long distance, the towline material can be saved and the frictional resistance of the towline at the time of laying the submarine pipe can be advantageously reduced. Moreover, since the winching operation of the pipe body is superior in operability (responsiveness) compared to dredgers, laying work can be facilitated.

  Next, the present invention will be described in detail based on the illustrated embodiment.

  1 and 2 show a first embodiment of the present invention, and are a side view and a plan view in which the present invention is applied to a construction method in which a deep-sea water intake pipe is laid on the seabed.

  In the long tube production yard 1 on land, a plurality of short pipes (single pipes) 2a of about 12 m are connected in series, and the intake pipe 2 is made into a long pipe by making it long, and a plurality of rollers 3 are directed to the sea side. It is placed on each roller 3 of the launching facility arranged diagonally. The end portion of the towline 5 fed from the winch 8 mounted on the DPS dredger 4 disposed offshore is connected to the tip connecting portion 2 c of the intake pipe 2 via a connector 13. The frame 6 attached to the tip of the intake pipe 2 is for taking water at a predetermined height from the sea bottom 7. In order to reduce the weight in water, the water intake pipe 2 is attached with a water stop lid at the tip and laid in a dry state. However, after the laying is completed, the water stop cover at the tip water intake must be removed. However, since the intake pipe of the deep sea water has a large water depth of 200m or more, normal diver work is not possible. After laying is completed at the tip of the intake pipe 2, water is poured into the intake pipe on the ground. Temporary lid 10 that is pressed and removed by remote operation is mounted

  In laying the intake pipe 2, the conventional laying work was performed by stopping the dredger (work ship) at a fixed position using an anchor, so that the hull moves due to the change in the catenary shape of the anchor wire. However, the present invention improves this point.

  That is, in the present invention, the DPS dredger 4 that draws out the intake pipe 2 is equipped with the GPS 12 and the propulsion device 11. A DPS (Dynamic Positioning System) uses a GPS (Global Positioning System) 12 that measures a ship position (longitude, latitude) in real time using an artificial satellite 12a, and a propulsion unit 11 that freely controls the propulsion direction of the hull 360 degrees. While the ship position is measured and confirmed by the GPS 12, the dredger is controlled by the propulsion unit 11 and automatically held at a fixed point. 12b in the figure is a GPS antenna that receives radio waves from the artificial satellite 12a.

  The propulsion device includes a plurality of the propulsion devices (thrusters) 11 capable of controlling the propulsion direction at the bottom side ship bottom of the hull. The DPS dredger 4 shown in FIG. 2 is an example in which one propulsion device 11 is provided on the bow / stern side.

  The DPS dredger 4 inputs the designated coordinates (longitude, latitude) of the laying route of the intake pipe 2 determined in advance and drives the propulsion unit 11, whereby the DPS dredger 4 moves to the designated coordinate position. The position can be automatically held. Coordinates can be input using pre-programmed data, input from a keyboard, or maneuvered with a joystick.

  To draw out the intake pipe 2, the towline 5 connected to the tip of the intake pipe 2 is wound around the winch 8 on the DPS dredger 4 while the DPS dredger 4 is held in the same place offshore, and is taken by winch operation. The water pipe 2 can be laid out and laid. (The dotted line in FIG. 1 indicates the towing state during the laying of the intake pipe 2)

  If a tension winch capable of changing the set tension is used as the winch 8, the intake pipe 2 can be laid with a constant tension applied to the towline 5 at all times. It is possible to prevent excessive tension from being generated in the cable 5 and the intake pipe (submarine pipe).

  As a means for laying a submarine pipe using the DPS dredger 4, there is a method shown in FIG. In this laying method, the tip connecting portion 2c of the intake pipe 2 is connected to the DPS dredger 4 by the towline 5, and the hull is positioned by the GPS 12 toward the laying line of the intake pipe 2 as shown by the solid line from the dotted line in FIG. However, the DPS dredger 4 is moved by the propulsion unit 11.

  In this laying method, it is only necessary to directly connect the towline 5 connected to the tip of the intake pipe 2 to the DPS dredger 4, so that the length of the towline 5 can be shortened, and the frictional resistance of the towline 5 when the submarine pipe is laid. This is advantageous in extending the laying over a long distance in terms of being able to remarkably reduce the distance.

  In addition, the pipe towing line 5 wound around the winch 8 of the DPS dredger 4 is unwound and the DPS dredger 4 is moved in the direction of the laying line, stopped at a predetermined position, measured by the GPS 12, and held by the propulsion unit 11. However, it is also possible to repeat the work of rolling out and laying the tube by a winch operation to extend the laying.

This laying method can shorten the length of the towline 5, so when applied to a submarine laying pipe whose laying extension extends over a long distance, the towline material can be saved and the frictional resistance of the towline 5 when laying the submarine pipe is significantly reduced. This is advantageous in that it can be done. In addition, since a winch that is excellent in operability (responsiveness) is used for the tube-out operation, laying work can be facilitated.

It is explanatory drawing which shows the aspect which enforces the submarine pipe laying construction method which concerns on Embodiment 1 of this invention. It is a top view of FIG. It is explanatory drawing which shows the aspect which enforces the submarine pipe laying construction method which concerns on Embodiment 2 of this invention. It is explanatory drawing which shows the aspect of the submarine pipe laying construction method in the deep water of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Long pipe production yard 2 Intake pipe 2a Intake pipe short pipe 2b Intake pipe tip 2c Intake pipe tip connection part 3 Roller 4 DPS dredger 5 Towing rope 6 Frame 7 Sea bottom 8 Winch 10 Temporary lid 11 Propulsion machine 12 GPS
12a Artificial satellite 12b GPS antenna 13 Connector 14 Work ship 15 Anchor wire

Claims (4)

  GPS and propulsion equipment are installed in the submarine pipe towing method where pipes added on the long pipe production yard on land or on a trolley are laid out on the ocean floor by dredging offshore via a launching facility. Place the DPS dredger offshore, hold the dredger at a fixed position with the propulsion device while moving the dredger position with the GPS or move along the laying line, and lay out the submarine pipe without anchoring the dredger Submarine pipe laying construction method characterized by this.   A towline that is fed from a winch at the stern of a DPS dredger equipped with GPS and a propulsion unit is connected to the tip of the pipe, and the DPS dredger is held at the same location on the offshore laying line. The submarine pipe laying method according to claim 1, wherein   A towline connected to the stern of a DPS charter equipped with GPS and a propulsion unit is connected to the tip of the pipe, and the pipe is spun out while moving the towed ship along an offshore laying line. 1. Submarine pipe laying method according to 1.   Connect the towing line that is fed from the winch at the stern of the DPS dredger equipped with GPS and propulsion equipment to the tip of the pipe, move the DPS dredger along the offshore laying line while unraveling the tow line, and put it in place 2. The submarine pipe laying method according to claim 1, wherein the pipe body is laid and extended by repeatedly rolling out the pipe body by a winch operation while stopping and holding the position.

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