GB2153332A

GB2153332A - Submarine conduit connection apparatus

Info

Publication number: GB2153332A
Application number: GB08426013A
Authority: GB
Inventors: Kenji Yamada
Original assignee: Mitsui Ocean Development and Engineering Co Ltd
Current assignee: Mitsui Ocean Development and Engineering Co Ltd
Priority date: 1984-01-28
Filing date: 1984-10-15
Publication date: 1985-08-21
Also published as: JPS60158100A; GB8426013D0; GB2153332B; JPH0255320B2

Abstract

A buoy (3) is anchored in the sea above the sea bottom (B) but below the wave action at the surface (S) of the sea, the buoy carrying interconnection means (4) between a lower section (5) of at least one feed conduit which is connected to a submarine device (6) on the sea bottom and an upper section (8) of the feed conduit which is connected to equipment (7) floating at the surface of the sea. A rigid body (9) projects upwardly from the buoy and supports the upper section(s) of the feed conduit(s) to limit the displacement of the upper section(s) where wave action occurs. The interconnection means are detachable to enable the upper section(s) to be separated from the lower section(s) when the floating equipment is to be moved. <IMAGE>

Description

SPECIFICATION Submarine conduit connection apparatus The present invention relates to apparatus for anchoring submarine feed conduits of which one ends are connected to submarine devices on the sea bottom and the other ends are attached to equipment floating on the sea.

In the past, for example where fluids such as crude oil or natural gas are fed from a submarine oil well to facilities on the sea such as boats anchored on the sea, or where driv ing fluids are fed to equipment installed un dersea, hoses for feeding the fluids are con nected between the submarine oil well or the submarine equipment at one end and facilities floating on the sea at the other end. However, the hoses are liable to be affected by sea weather conditions such as waves or wind as the hoses come close to the surface of the sea and, as a result, the hoses are caused to sway, leading to fatigue and short service life.

In addition, when the facilities floating on the sea are evacuated in stormy weather, the hoses have to be raised from the bottom of the sea and moved, and considerable labour and time is required to pull up the hoses.

Moreover, since the connection for detachably connecting the hoses to the submarine de vices is located on the bottom of the sea, it has been difficult to maintain and check the connections.

In accordance with the invention, apparatus for providing connection between at least one submarine device and equipment floating on the surface of the sea comprises a a buoy, an anchor which is arranged to lie on the bottom i of the sea, flexible tension members extending from the buoy to the weight for suspending the buoy, in use, in the sea at a level substan tially below wave action at the surface of the sea, interconnection means on the buoy, at least one lower conduit section which is ar ranged to be connected at its lower end to the submarine device and connected at its upper end to the interconnecting means, at least one upper conduit section which is connectible at its lower end to the interconnecting means, and extends upwardly for engaging and con necting with the floating equipment, the up per conduit section having at least one flexible part permitting, in use, the floating equipment to move up and down relatively to the buoy without disconnecting the upper conduit sec tion from the buoy or from the floating equip ment, and the interconnecting means provid ing interconnection between the lower and upper conduit sections to afford, in use, com munication between the device or devices and the equipment.

The disadvantages noted above with respect to prior art are thus removed by the present invention. The buoy which, in use, is an chored in the sea above the sea bottom but below the wave action at the surface of the sea, provides releasable interconnection means between the lower section(s) of the feed conduit(s) which is/are connected to the submarine device(s) and the upper section(s) of the feed conduit(s) which is/are connected to the floating equipment.

Preferably, a rigid support means projects upwardly from the buoy and the upper section(s) of the feed conduit(s) is/are mounted thereon to limit the displacement of the upper sections of the conduit(s) in the part of the sea where wave action occurs.

A marine work station incorporating equipment in accordance with the invention is illustrated in the accompanying schematic drawing.

As illustrated conduits are connected between a ship or other floating structure 7 which floats at the surface S of the sea and submarine devices 6 mounted on the sea bottom B. The floating structure may be on oil barge, a drilling rig, or other suitable equipment, and the submarine devices may be well structures or other equipment for collecting crude oil or natural gas from a submarine oil well. Alternatively the submarine devices may comprise other devices which are useful for collecting material from the sea bottom, for example harvesting equipment for harvesting flora or fauna, or salvage equipment for salvaging materials which have fallen to the sea bottom. In collecting oil and gas, the devices are connected to the floating structure by hoses to permit the transfer of fluids.In the case of harvesting or salvage, the structures may be connected to the floating structure by cables or electronic connecting devices which permit manipulation of the submarine devices to accomplish their purpose. Thus the conduits may comprise either hoses or electrical conductors, depending upon the submarine equipment to which they are connected.

Means is provided to permit disconnection of the conduits between the submarine devices 6 and the floating equipment 7, for example when the floating equipment is subjected to severe wave action, as in storms or when it is desirable or necessary to remove the equipment for servicing.

A conduit-interconnecting means 4 is provided between lower sections 5 and upper sections 8 of the conduit. The lower ends of the sections 5 are connected to the submarine devices 6 and are connected at their upper ends to the interconnecting means 4. In like manner the upper ends of the conduit sections 8 are connected to the floating equipment 7 and the lower ends of thse conduits are connected to the interconnecting means 4.

The conduit-interconnecting means 4 is mounted on a buoy 3 which is anchored above the sea bottom B at a level of the sea which is not affected by wind and waves.

Preferably the buoy is anchored by wire ropes or other tension members 2 to a weight or other anchor 1 sunk on the floor of the sea bottom B. As is well known, the buoyant force of the buoy 3 will hold the wire ropes generally upright, depending upon any transverse currents which may apply a lateral force upon the buoy as it floats. The length of the wire ropes 2 determines the level at which the buoy 3 is suspended, and this level is sufficient to provide slack in the lower conduit sections 5 extending from the interconnecting means 4 to the submarine devices 6.

The upper conduit sections 8 extend from the floating equipment vessel 7 to the interconnecting means 4 and rigid support means 9 is provided between the floating structure 7 and the buoy 9. As shown in the drawing, the rigid structure comprises an upright mast detachably mounted on the buoy 3 at its lower end and extending through a well 10 in the body of the floating structure 7. The upper conduit sections 8 extends along the mast 9 and are provided with loops 11 at their upper end which are enclosed in the well 10 to enable the floating structure 7 to move under wave action without stressing the conduit sections 8. At the upper end, the conduits are connected to pumps, in the case of fluid conduits, or power supplies in the case of electrical conduits so as to enable the conduits to feed either fluid or power between the equipment 7 and the submarine devices 6.

The presence of a rigid mast extending from the buoy to the floating structure, and the mounting of the conduit section 8 along the length of the mast isolates the major extent of the conduit section 8 from flexing and from contact with debris or fish which might be floating in the sea immediately below the surface. The isolation of the section from damage by waves or impact, extends the service life of these conduit sections by eliminating bending or fatigue.

Since the buoy 3 is suspended near the surface of the body but just below the area subject to wave action, the buoy is readily accessible to permit connection and disconnection of the upper conduit sections 8 and the rigid mast 9 from the interconnecting means and the buoy. Thus in stormy weather it is a relatively simple procedure to disconnect the upper conduit sections from the interconnecting means 4 and to withdraw these sections into the vessel 7. At the same time the rigid mast 9 may also be disconnected from the buoy, or it may be left in place if it is desired to provide a marker for identifying the location of the buoy.

Claims

1. Apparatus for providing connection between at least one submarine device and equipment floating on the surface of the sea, the apparatus comprising a buoy, an anchor which is arranged to lie on the bottom of the sea, flexible tension members extending from the buoy to the weight for suspending the buoy, in use, in the sea at a level substantially below wave action at the surface of the sea, interconnection means on the buoy, at least one lower conduit section which is arranged to be connected at its lower end to the submarine device and connected at its upper end to the interconnecting means, at least one upper conduit section which is connectible at its lower end to the interconnecting means, and extends upwardly for engaging and connecting with the floating equipment. the upper conduit section having at least one flexible part permitting, in use, the floating equipment to move up and down relatively to the buoy without disconnecting the upper conduit section from the buoy or from the floating equipment, and the interconnecting means providing interconnection between the lower and upper conduit sections to afford, in use, communication between the device or devices and the equipment.

2. Apparatus according to claim 1, wherein the flexible tension members are wire ropes.

3. Apparatus according to claim 1 or claim 2, including rigid support means extending upwardly from the buoy, in use, towards the surface of the sea. and having means for mounting the upper conduit section on the support means to limited flexure of the section.

4. Apparatus according to claim 3, wherein the rigid support means comprises an upstanding mast which is arranged to project above the surface of the sea to constitute a marker for the buoy.

5. Apparatus according to claim 3 or claim 4, wherein the rigid support means is detachably connected to the buoy.

6. Apparatus according to any one of claims 3 to 5, in conjuncton with floating equipment having a well which receives, in use, the upper end of the rigid support means, the flexible part of the upper conduit extending from the upper end of the rigid support means to the floating equipment within the well.

7. A marine installation comprising apparatus according to any one of the preceding claims, wherein the anchor is lying on the bottom of the sea and the buoy is suspending in the sea at a level substantially below wave action at the surface of the sea.

8. A marine installation, substantially as described with reference to the accompanying drawing.