JPS6139172Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to towing fittings attached to the front and rear ends of a flowline when the flowline is towed from a land yard to a laying site by a towing vessel when a submarine pipeline called a flowline is laid by the submarine towing method or the floating submarine towing method, and this device transmits the towing force to the flowline during towing and protects the connecting fittings at the end of the flowline from damage, and when removing the towing fittings to connect the flowline to a well or a platform at the laying site underwater after towing, it makes it possible to use a disconnecting hook that can be operated by, for example, an ultrasonic signal without using heavy machinery or divers. Conventionally, in order to produce oil from the seabed, a platform was first constructed at the oil extraction site, and then a well was drilled from this platform. However, recently, particularly in the North Sea, a method of subsea completion of wells has begun to be adopted. This subsea completion method does not dig a well from a platform, but instead drills a well directly into the seabed without constructing a platform, and completes the well on the seabed. A pipeline called a flow line is then connected to the well, and the oil and petroleum gas are collected on a platform located a short distance away, from which point they can be transported further. Although the flow line essentially constitutes a pipeline, its structure is not limited to being a production line through which oil and gas pass, but also includes hydraulic lines that control the wellhead equipment,
It is a complex system that also includes important auxiliary equipment such as power cables and instrumentation cables, and is usually 1 to 3 km long. The entire length is prefabricated on land, and the production line, hydraulic lines, power cables, instrumentation cables, etc. are integrated together. It is then towed by a towing ship from the onshore yard to the site (between the subsea completion well and the platform installed in the center of the well).
The flow line d is towed to the destination and its both ends are connected to the well and platform as shown in Fig. 5. In Fig. 5, a is the oil layer, b is the seabed completion well, c is the platform, and d is the flow line. Fig. 6 shows the state where the flow line d is towed to the destination. By attaching a buoy i and a heavy water chain j over the entire length of the flow line d, it is possible to tow the flow line d to a depth of 1 to 2 m above the seabed surface.
The flow line is floated with the gap between the well and the flow line maintained, and a towing wire f is attached to the front and rear ends of the well, which are fixed to a towing vessel g and towed. As shown in Fig. 5, in order to connect the end of the flow line d to the completion well b on the seabed, a wet connection method is being developed that connects the production line, hydraulic line, power cable, instrumentation cable, etc. underwater with one touch. This is done by providing male and female connecting fittings on the well side and the flow line side, respectively. Note that e shown in Fig. 6 is the towing fitting of this invention, which will be explained in detail later, and this towing fitting has not been used in the past. Therefore, when towing a flow line in the past, the pipe ends of the flow line are exposed, and when these pipe ends come into contact with the seabed surface, the connecting fittings at the pipe ends are damaged or are inevitably soiled with sludge, which results in frequent failure to connect, which has been a problem. The present invention relates to a towing fitting that has been invented in order to solve the above problems. The characteristics and functions required for the towing fitting are as follows: (i) A towing force of several tens of tons is required due to the friction between the heavy water chain attached to the flow line and the seabed during towing, and therefore the towing fitting at the end of the flow line must have sufficient strength to transmit the towing force from the towing wire to the flow line. (ii) The towing fitting must have a structure that can protect the connecting fitting at the end of the pipe from being damaged or soiled with sludge even if the end of the flow line contacts the seabed during towing. (iii) The towing fitting must be easily removable without using heavy machinery or divers when connecting the flow line to the seabed completion well. The towing fitting of the present invention will be described below based on the embodiment shown in Figures 1 to 3. In the figures, reference numeral 1 denotes a flow line, and reference numeral 2 denotes a connecting fitting for the flow line. Although not shown in the figure, production lines, hydraulic lines, power cables, instrumentation cables, etc. are arranged inside this connection fitting 2. Also, although not shown in the figure, at the tip of this connection fitting 2, the connection joints for each of the lines, cables, etc. are lined up inside the flange.
It serves as a casing (sheath tube) for the connection joints of each cable, etc. In this invention, this part is simply referred to as the tube end, and this is within the scope of the flow line. 3 is the towing fitting body of this invention, 4 is a watertight can part provided at one end, and 4' is a cap part provided at the other end. 5 is a wire stopper piece for fixing the towing wire, which is provided at the tip of the watertight can part 4. The cap part 4' is fitted to cover the connection fitting 2 of the flow line 1 , so that the said part can be protected from damage and contact with the seabed. The watertight can part 4 is provided to obtain buoyancy, and offsets the steel weight of the towing fitting body 3 when towing, making its underwater weight zero or close to zero. As an example of a preferred embodiment, the outer diameter of the connection fitting 2 of the flow line 1 is
When the towing lug body 3 has a length of 1195 mm, the inner diameter of the cap portion 4' and the watertight can portion 4 of the towing lug body 3 is 1205 mm, the thickness of the steel material constituting the body is 16 mm, and the cap portion 4'
If the length of the towing hardware is 1300 mm and the length of the watertight can 4 is 2200 mm, the steel weight of the towing hardware body 3 is approximately 2082 kg.
The weight of the watertight can 4 underwater is -219 kg due to the buoyancy of the can. 6 and 7 are fasteners for fastening the breakaway hooks.
At least two pairs of are provided symmetrically on the outer peripheral wall of the cap portion 4', and at least two pairs of 7 are provided symmetrically on the outer peripheral wall of the connecting fitting 2. Two pin holes 8, 8' are drilled in the fastener 6, and a pin 9 is provided in the fastener 7. This relationship may be reversed. The pins are inserted into the pin holes 8, 8'. The breakaway hooks used to fasten the fasteners 6, 7 for fastening the breakaway hooks may be, for example, the normal breakaway hooks 10 shown in FIG. 4.
Reference numerals 11 and 11' of 10 are pin holes, and 12 is a hook. The pin holes 11 and 11' are aligned with the pin holes 8 and 8' of the fastener 6, and the hook 10 is fixed to the towing fitting body 3 by pinning it, and the hook 12 grips the pin 9 of the fastener 7, and locks the hook 10 , thereby fixing the towing fitting body 3 of the present invention to the pipe end of the flow line 1 , i.e., the connecting fitting 2. As is well known, the hook 10 utilizes the principle of releasing the lock by igniting the gas filled in the hook 10 using an ultrasonic signal. However, the applicant of the present application previously filed a utility model application 1981-1986, which discloses a method for releasing the lock.
If the underwater disconnecting device proposed in No. 142611 is used, the towing flowline and the towing fitting of the present invention can be removed more effectively. Next, the method of using the towing fitting of the present invention will be explained. First, the flowline 1 and the connecting fitting 2 forming the pipe end are fabricated on land, and at that point the towing fitting 3 of the present invention is placed over the connecting fitting 2 and the two are fixed together by the disconnecting hook 10. Next, the towing wire is tied to the wire hole 5' of the towing wire stopper piece of the towing fitting 3 , and the towing vessel is towed to the destination as shown in Fig. 6. The towing force in this case is approximately 15 tons, depending on the total length and pipe diameter of the flowline 1 , of course, but the towing wire stopper piece 5 → towing fitting body 3 → disconnecting hook fastener 6 → disconnecting hook 10 → disconnecting hook fastener 7 → connecting fitting 2
The signal is transmitted in this order. Even if the tip (pipe end) of the flow line 1 sinks into the seabed soil due to a loss of wire tension in the towing wire during towing, the tip of the connecting fitting 2 is safely protected because it is covered by the cap 4' of the towing fitting 3 of the present invention. In this way, when connecting one end of the flow line 1 to the seabed completion well after towing, the disconnecting hook 10 can be unlocked by an ultrasonic signal from a remote location, allowing a one-touch connection using the wet connection method described above. Disconnecting hook 1
When the lock 0 is released, the towing wire is pulled up to the towing vessel, where the towing fitting 3 and the release lock 10 are retrieved while still fixed in series. The towing fitting of this invention (a) perfectly transmits the towing force, and (b) perfectly protects the connecting fittings. In addition, since a release hook that is activated by an ultrasonic signal or the like is used to remove the towing fitting, it can be removed without a diver even at great depths. Furthermore, in order to prevent any change in the floating/sinking balance of the end of the flow line before and after the removal of the towing fitting, a watertight can section is provided in the towing fitting itself so that its underwater weight is zero or close to zero, and other effects are achieved.

[Brief explanation of drawings]

Figures 1 to 3 show an embodiment of the towing fitting of the present invention, in which Figure 1 is a front view, Figure 2 is a partially cutaway side view, and Figure 3 is a side view of the tip. .
FIG. 4 is a plan view of the separation hook. FIG. 5 is a cross-sectional explanatory diagram when a submarine pipeline is laid by the flow line method, and FIG. 6 is a cross-sectional explanatory diagram when the flow line is towed. 1 ...Flow line, 2...Connection fittings, 3 ...
Towing metal fitting body, 4... Watertight can part, 4'... Cap part, 5... Towing wire stopper piece, 5'... Wire hole, 6, 7... Breaking hook fixing fitting, 8,
8'...Pin hole, 9...Pin, 10 ...Separation hook, 11, 11'...Pin, 12...Hook.

Claims (1)

[Scope of utility model registration request] A towing fitting for an undersea pipeline, characterized in that one end of the towing fitting body is provided with a wire fastener for fixing the towing wire and a watertight can section for obtaining buoyancy, and the other end is provided with a cap section for protecting the pipe end of the pipeline to be towed, and hook fasteners are provided on the outer peripheral wall of the cap section and on the outer peripheral wall of the connecting fitting at the end of the pipeline to be towed, and these two hook fasteners are fixed between each other with a disconnecting hook, and the disconnecting hook is filled with gas that is ignited by an ultrasonic signal, and the lock is released by ignition of the gas.