WO1999035513A2 - Marine devices - Google Patents

Abstract

A submarine exploration system comprising at least one submarine assembly having (3) at least one signal detector; and a buoy (5) connected to said submarine assembly, said buoy having wireless communications means for transmitting said detected signals. A submarine assembly, a buoy and a marine vessel are also described.

Description

MARINE DEVICES

This invention relates generally to marine devices.

A first aspect of the invention relates, more particularly, to submarine sensing systems, such as seafloor seismic exploration systems. There are currently two principle seafloor seismic exploration systems. A first system employs hydrophones that each comprise a crystal that is compressed by sound waves to generate a voltage signal. A second system employs geophones (typically in combination with hydrophones) that each comprise a magnet which is movable within a coil to generate a voltage. The voltages are then interpreted to build-up a picture of the submarine structure of the earth in the test location.

In the first system, a vessel tows a number of streamers (typically between 6 and 20, each of six kilometres or more in length) each containing a plurality of hydrophones. The hydrophones record reflected sound waves generated by a pneumatic source, for example, which is towed either behind the same vessel or behind another following vessel. The source generates sound waves that travel through the water medium and are reflected by boundaries between different rock formations below the seabed. By recording the reflected soundwaves, it is possible to build a diagrammatic representation of the structure of the earth beneath the seabed, and to locate oil traps, reservoirs or foimations that are likely to contain such traps or reservoirs.

Although this arrangement has been successfully commercially employed for many years, it cxliibits a number of serious disadvantages. The chief disadvantage is that this arrangement does not permit the recording of shear waves, as these waves are not transmitted through the water medium. The recording of shear waves is particularly desirable as a means for further determining rock properties, that determination not being particularly successful with P or compressional waves alone.

A further disadvantage is that this system is particularly susceptible to noise, such as submarine noise or noise generated at the surface of the sea during stormy weather, for example. Furthermore, the vessels towing the streamers are very difficult to control as they cannot easily stop and must undertake long, time-consuming turns to reduce the likelihood of the deployed streamers becoming tangled. A further disadvantage is that sophisticated tracking and positioning equipment is required to determine the exact location, in real time, of each of the hydrophones on the streamers. To alleviate these problems, the second system - .known in the art as OBS (Ocean Bottom Seismic) - was developed. OBS involves the placing of a large number of geophones, usually in combination with hydrophones, on the seabed. The geophones and hydrophones are typically deployed in pairs at locations spaced 50m apart along linear arrays that can be as much as twelve kilometres in length. A plurality of arrays are deployed and are connected to a stationary recording vessel which records signals from the 'phones and supplies power thereto.

Whilst the OBS system alleviates some of the problems associated with the first system, it also exhibits a number of serious disadvantages. The chief disadvantage associated with the OBS system is cost. In order for the system to be operated effectively, it typically must employ a minimum of four separate vessels - a first pair to deploy the arrays, a third to cairy and operate the signal generating equipment and a fourth, stationary, vessel for recording signals from the arrays. The fourth recording vessel is connected to the arrays by jumpers which are extremely vulnerable to breakage, and thus it is essential for the recording vessel to be kept in the same position at all times when connected to the arrays. A further problem is that the repeated deployment and storage of the arrays can cause the cables to be broken or frayed, thereby increasing the amount of maintenance required to keep the system operational.

It is apparent therefore that a need exists for a system that alleviates some or all of the problems associated with the above mentioned systems. Accordingly, it is an aim of the present invention to provide just such a system.

-In accordance with this first aspect of the invention, there is provided a submarine exploration system comprising: at least one submarine assembly having at least one signal detector; and a buoy connected to said submarine assembly, said buoy having wireless communications means for transmitting said detected signals.

Preferably, the system comprises a remote station for receiving said transmitted detected signals and/or signal generating means. Preferably, the signal generating means is mounted on a vessel which is capable of deploying said buoy and said submarine assembly. Alternatively, the signal generating means may be mounted on a separate vessel to that which is capable of deploying said buoy and said submarine assembly.

Preferably, the submarine assembly comprises at least one hydrophone and/or at least one geophone. More preferably, the submarine assembly comprises three geophones. Most preferably, the submarine assembly comprises an elongate mounting arm and a first of said geophones is mounted in parallel to said arm, a second of said geophones is mounted substantially perpendicularly to said arm, and a third of said geophones is mounted at right angles to said first and second geophones. This arrangement enables shear waves to be detected. Preferably, said submarine assembly also comprises tlxree hydrophones mounted at spaced locations on said arm.

Preferably, said submarine assembly comprises means for indicating the location of the assembly. The indicating means may further indicate the alignment of the assembly. The indicating means may comprise a pair or transponders mounted on said assembly at spaced locations from one another.

Preferably, the buoy comprises an impact resistant housing having an internal cavity sealed against water ingress; power means for powering said wireless communications means; and an antenna by means of which said signals are transmitted to said remote station. Preferably, the buoy comprises float means for maintaining the buoyancy of the buoy. Preferably, the wireless communications means comprises a UHF radio transmitter and/or the power means comprises one or more batteries and/or the power means comprises one or more solar cells foπning an integral part of the housing. Preferably, the solar cells form at least part of a lid that is capable of closing the internal cavity of the housing. The antenna may be mounted on the buoy via a spring loaded mounting.

Preferably, the underside of the buoy is provided with an eyelet to which a kelum grip may be attached. Preferably, the impact resistant housing is of tough ABS plastic. Preferably, the float means comprises closed cell polyurethane foam. The float means may be integrally formed with the housing.

Preferably, the system comprises a submarine cable attached at one end to said transmitting means and at the other end to the submarine assembly, the signals detected by said detecting means being passed to said transmitting means for transmission.

The wireless communications means may comprise a receiver for receiving signals transmitted from said remote station. The receiver may be a UHF receiver.

Preferably, the submarine assembly is installed, in use, on the seabed and/or the buoy is capable of floating on or near the surface.

In accordance with the first aspect of the invention, there is also provided a method of submarine exploration comprising: deploying at least one submarine assembly connected to a buoy; detecting signals with one or more signal detectors provided on said submarine assembly; and transmitting said detected signals from said buoy with wireless communications means provided within said buoy.

A second aspect of the invention relates to marine buoys, and more particularly to buoys that are suitable for use with the above mentioned exploration system.

A large number of different types of buoys have previously been proposed. However, none of these buoys .are suitable for use with the above mentioned exploration system, nor are they generally suitable for use in the extreme conditions often encountered during marine exploration.

If buoys are to be deployed during marine exploration, then these buoys should be extremely hardy and capable of withstanding rough weather. They should also be able to withstand collisions with shipping without adversely affecting the operating capacity of the buoy. Furthermore, they should be relatively maintenance free as they are typically deployed far from shore and thus cannot easily be returned to shore, or on-board ship, for maintenance.

In accordance with this second aspect of the invention, there is provided a buoy for a submarine exploration system, the buoy comprising: an impact resistant housing having an internal cavity sealed against water ingress; wireless transmitting means provided within said housing for wireless transmission of signals to a remote station; power means for powering said transmitter; and an antenna by means of which said signals are transmitted to said remote station.

Preferably, the buoy comprises float means for maintaining the buoyancy of the buoy. Preferably, the transmitting means comprises a UHF radio transmitter.

Preferably, the power means comprises one or more batteries. Preferably, the power means also comprises one or more solar cells forming an integral part of the housing. Preferably, the solar cells farm at least part of a lid that is capable of closing the internal cavity of the housing.

The antenna is preferably mounted on the buoy via a spring loaded mounting. Preferably, the underside of the buoy is provided with an eyelet to which a kelum grip may be attached.

The impact resistant housing may be of tough ABS plastic. The float means may comprise closed cell polyurethane foam. The float means is preferably integrally foimed with the housing.

Preferably, the buoy comprises a submarine cable attached at one end to said wireless communications means and at the other end to a submarine assembly having signal detecting means, the signals detected by said detecting means being passed to said transmitting means for transmission to said remote station.

A third aspect of the invention relates, more particularly, to submarine assemblies and to submarine seismic sensing assemblies. As described above, it has previously been proposed to provide a large number of signal detectors connected at spaced linear intervals to a line towed behind a vessel. As an alternative to this system, it has been previously proposed to lay long signal detector arrays on the seafloor (the OBS system). Both of these systems exliibit a number of disadvantages. The OBS system is disadvantageous as it requires a large number of vessels in order to be effectively employed. Furthermore, the laying of long arrays is inconvenient and expensive. The other previously proposed system is inconvenient as the lines towed behind the vessel severely reduce the manoeuvrability of the vessel and can become tangled. Furthermore, neither of these previously proposed systems provide particularly accurate results.

In accordance with this third aspect of the invention, there is provided a submarine sensing assembly comprising: an elongate mounting arm having one or more signal detectors connected thereto. Preferably, the assembly comprises: at least three signal detectors connected thereto, the first signal detector being aligned substantially perpendicularly to the mounting arm, the second signal detector being aligned substantially in parallel to the mounting arm, and the third signal detector being aligned substantially at right angles to the first and second signal detectors and to the mounting arm.

This aspect of the invention alleviates the problems associated with previously proposed systems as it does not require the laying of long linear submarine detector arrays. Instead, a plurality of the submarine assemblies can be deployed, each of the submarine assemblies being more easily laid and subsequently recovered than previous systems. Furthermore, the particular arrangement of detectors employed in this aspect of the invention enables the accuracy of the readings taken to be improved.

Preferably, the first, second and third signal detectors are geophones. In this way, the detection of signals can be improved as the geophones allow the detection of shear waves. Preferably, the elongate mounting arm is of brass.

Preferably, one end of the arm is provided with an eyelet to which an anchor or the like may be connected to reduce drifting of the assembly. Preferably, the detectors are each mounted on the arm via a gimbal. Preferably, the submarine assembly comprises a housing within which said detectors are provided. Preferably, the housing is provided with an eyelet to which a kelum grip or other suitable connector may be attached.

Preferably, the assembly comprises an umbilical connected at one end to the detectors of the assembly and at the other end to a buoy. Preferably, the umbilical is braided over its full length in kevlar fibre. Preferably, the arm is connected to a spring rod and/or the spring rod is approximately 2m in length. Preferably, an acoustic transponder is provided on the end of the rod furthest from the arm. A second acoustic transponder may be provided on the other end of the submarine assembly.

Preferably, the submarine assembly comprises one or more hydrophones. More preferably, the assembly comprises three hydrophones. Preferably, the hydrophones are spaced from one another along the assembly.

A fourth aspect of the invention relates to marine vessels and in particular to marine vessels which are operable to recover the above described buoys and submarine assemblies. As discussed above, there are two principal previously proposed submarine exploration systems. Both of these systems require long, linear arrays to be handled. Towed Hydrophone Arrays are recovered onto large reels at the stern, for storage. Maintenance has to be performed in water, usually whilst deploying or fully deployed from a smaller vessel. OBS cables are recovered over the bow, via a large diameter drum, acting as a cable-bend restrictor. Storage of the cable is in large 'bins', (usually the vessels main deck, divided into one or more sections) and require to be fed into the bin via the stem to allow redeployment in the correct manner (in a first on last off sequence.). Maintenance here occurs whilst the cables are onboard. OBS cables allow access to individual arrays, which can be replaced if they fail. Towed streamer arrays require entire sections to be replaced. However, due to the nature of streamer work, where the equipment can be deployed and remain out for weeks or months without recovery, failures are less. OBS cables, on the other hand, due to daily recovery and deployment, suffer very great failure rates.

In accordance with this fourth aspect of the invention, there is provided a marine vessel comprising a conveyor belt that is operable to convey items from the surface to the vessel. This aspect of the invention provides an arrangement which removes the need for a large diameter rotating drum and thus addresses the inefficiencies associated with the previously proposed arrangement.

Preferably, the vessel is a catamaran. Preferably, the conveyor belt extends from the surface, or from just below the surface, to the vessel. Preferably, the conveyor belt has a coarse mesh. Preferably, the conveyor belt is of kevlar.

Preferably, the conveyor belt is provided with engaging means that rotate with the belt and can engage with items floating at or near the surface to subsequently convey them within the vessel. Preferably, the engaging means comprises a series of stainless steel wire hoops. More preferably, the engaging means comprise two rows of hoops that extend from either lateral edge of the belt to leave a channel therebetween.

Preferably, a rail is provided either side of the belt to reduce the likelihood of retrieved items being washed off the belt. Preferably, the conveyor belt is attached at one end to one or more arms that are operable to move the end of the conveyor belt away from the surface. Preferably, the end of the belt is lowerable to an angle of up to 45° below the horizontal. Preferably, the end of the belt is lowered to an angle of approximately 32° below the horizontal during use. Preferably, the conveyor belt extends, in use, downwardly towards the bow of the vessel. o

Preferably, a wheeled drive mechanism is provided within the vessel. Preferably, the drive mechanism comprises four close coupled driven tyred wheels that can engage and transport any items retrieved by the conveyor belt. Preferably, the vessel comprises a storage rail mechanism within the vessel so that items retrieved can be stored. Preferably, the storage mechanism comprises a plurality of trolley units movably mounted on a rail, each trolley unit comprising a first trolley for supporting a buoy, a second trolley for supporting an umbilical and a third trolley for supporting a submarine assembly.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic representation of a submarine exploration system;

Figure 2 is a schematic representation of a buoy;

Figure 3 is a schematic representation of a submarine assembly;

Figure 4 is a schematic representation of a marine vessel; and Figure 5 is a schematic representation of a unit of a rail storage mechanism.

Figures 6 and 7 are schematic representations of an illustrative catamaran.

The various aspects of the invention will now be described with reference to an illustrative deployment at sea. However, it should be noted that the invention may be employed in any marine environment, whether that environment be a freshwater environment or a saltwater environment. Accordingly, any reference herein to a marine environment or to a sea environment should be understood to include both fresh and salt water environments.

As in the .known OBS system, two linear arrays spaced by 50m, for example, are set up. In accordance with this example of the invention, each array comprises a plurality of submarine assemblies each connected to a respective buoy.

With reference to Figure 1, the submarine exploration system 1 comprises a plurality of submarine assemblies 3 each connected to a respective buoy 5. Each of the buoys is provided with an antenna 7 and transmitting means.

illustrative example of a suitable submarine assembly and a suitable buoy will be later described. The submarine assemblies detect reflected soundwaves and generate signals indicative thereof which are subsequently passed to the buoys for transmission to a remote station 9. y

The remote station 9, which in this example is a marine vessel, is equipped with an antenna 11 and the appropriate equipment to permit reception of signals transmitted from the various buoys 5. The remote station may solely be employed as a signal receiving station, or more preferably may also be employed as a deployment vessel for deploying the submarine assemblies,

illustrative example of a suitable vessel will be later described.

In use, signal generating means (not shown) are employed to generate signals, for example soundwaves, which travel through the marine medium and through a portion of the earth therebelow. The soundwaves are reflected by transitions between different rock types and by other underground formations. These reflected soundwaves are subsequently detected by the submarine assemblies and signals are generated in response thereto. The detected signals are passed to the transmitters for transmission to the remote station. The sound generating means may comprise a pneumatic pulse generator, an explosive source or any other suitable signal generating means. Advantageously, the signal generating means could be mounted on the remote station so that a single vessel may be employed for the generation and reception of signals, and for the deployment of submarine assemblies and buoys.

.An illustrative example of a suitable buoy will now be described with reference to Figure 2. It should be noted however, that this buoy may be utilised with systems other than those described above.

As shown in Figure 2, the buoy 5 comprises an impact resistant housing 20 having an inner cavity 22. The cavity is sealable against water ingress by a lid 24 which in one embodiment may comprise one or more solar cells. .An antenna 26 is spring-mounted on the lid 24 of the buoy and is connected to a signal transmitter 28 provided within the sealed cavity 22 of the buoy 5. The antenna may be provided with reflective tape 30 or other reflective devices to improve the visibility of the buoy. Power means 32, for example batteries, are provided within the sealed cavity and are preferably connected to the underside of the lid 24 for easy removal therewith. The batteries are connected to the transmitter and to the solar cells, if provided, to supply power to the transmitter. The solar cells are provided to extend the time between battery charges particularly for those situations where battery recharging cannot easily be accomplished. The transmitter preferably includes a flash memory so that a number of readings may be taken and then subsequently transmitted, rather than making large numbers of individual transmissions. Preferably, the number of available transmission channels corresponds to the number of signal detectors provided on the submarine assembly. In the preferred embodiment, the transmitter has six channels and utilises 24 bit delta-sigma transmission to provide a two way communications link to the remote station. Preferably, the transmitter uses a digital modulation technique to transmit data at a very high data rate over a reduced spectrum (for example between 68 to 88 MHz or 220 to 238 MHz). The transmitter is preferably a low power transmitter with a range of 4kms at 100 mW, 20.kms at 1 W and 351 ms at 10W.

The underside of the buoy 5 is provided with an eyelet 34 to which a suitable connector such as a kelum grip 36 may be attached. The kelum grip 36 supports an umbilical 38 which is connected at one end to the transmitter 28 and at the other end to the submarine assembly (to be later described). The umbilical is attached to the buoy via the kelum grip to reduce the likelihood of the umbilical capsizing the buoy, and to reduce the strain placed upon the connection between the umbilical and the transmitter. The composition of the umbilical will later be described in conjunction with the submarine assembly.

The impact resistant housing 20 of the buoy 5 is preferably of ABS plastic, or some other suitably tough material. The interior cavity is preferably filled with a buoyancy aid, such as closed cell polyurethane foam, that also defines suitably shaped cavities into which the batteries and transmitter may be inserted. The housing and buoyancy aid may be formed at the same time by an injection moulding process, for example, or may be formed separately and then subsequently joined. Preferably, the batteries are located towards the base of the buoy so that the centre of gravity of the buoy is kept as low as possible in the water.

space above the batteries may then be filled with removable sections of closed cell polyurethane foam. illustrative example of a submarine assembly will now be described with reference to Figure 3. However, it should be noted that the submarine assembly described below could be utilised with exploration systems or buoys other than those described above.

With reference to Figure 3, the submarine assembly 40 comprises an elongate mounting arm 42 which is preferably of brass or another dense corrosion resistant material. The mounting arm helps to keep the submarine assembly in close contact with the seafloor, and thus helps the geophones to couple effectively with the seabed. One end of the arm 42 is provided with an eyelet 43 to which an anchor or the like (not shown) may be connected to reduce drifting of the assembly.

A first geophone 44 is connected to the arm 42 and is aligned parallel thereto. A second geophone 46 is connected to the arm 42 and is aligned substantially perpendicularly thereto. A third geophone 48 is connected to the arm 42 and is aligned at right angles to the other geophones and to the arm 42. In this way, the three geophones are aligned along the x, y, and z axes with respect to the arm. The geophones may be directly mounted on the arm or, more preferably, they may be secured within a housing 50 that is mounted on the arm. It is further preferred that the geophones are each mounted on the arm via a gimbal so that they are correctly oriented with respect to the vertical. The housing 50 is provided with an eyelet 52 to which a kelum grip or other suitable connector may be attached. An umbilical 54 (which may be the same umbilical shown in Figure 2) is connected at one end to the various detectors of the submarine assembly and at the other end (not shown) to a buoy, for example. The umbilical 54 is braided over its full length in kevlar fibre which is supported by the kelum grip so that the umbilical may be used to lift the submarine assembly upon the retrieval thereof..

The arm 42 extends beyond the housing and is connected to a spring rod 56 that is preferably approximately 2m in length. An acoustic transponder 58 is provided on the end of the rod 56 furthest from the housing 50. A second acoustic transponder 60 is provided on the other end of the submarine assembly close to the housing 50. The acoustic transponders 58, 60 enable the location and alignment of the submarine assembly to be accurately determined. A spacing of 2m meters between the two transponders enables the alignment of the assembly to be determined to a resolution of better than 10 degrees. In addition to the three geophones, it is preferred that three hydrophones are also provided. The first hydrophone 62 is preferably provided within the housing 50 and the second and third hydrophones 64, 66 are preferably spaced from one another along the rod 56. The combination of hydrophones and x-y-z aligned geophones enable particularly accurate readings to be taken.

.An illustrative example of a marine vessel that is operable to retrieve the above described buoys and submarine assemblies will now be described with reference to Figure 4. However, it should be noted that the marine vessel described below could be used to recover a variety of alternative items.

Figure 4 shows a schematic cross-sectional view of a vessel 70. In the preferred embodiment, the vessel is a catamaran and only one hull 72 is shown in Figure 4. As shown, the vessel 70 includes a conveyor belt 74 which extends from the surface, or just below the surface, to the interior of the vessel 70. The conveyor belt 74 is provided with engaging means 76 that rotate with the belt and can engage with buoys or other items floating at or near the surface to subsequently convey them within the vessel 70. Preferably, the conveyor belt has a coarse mesh and is of kevlar. In this way, the belt allows the water to flow freely though it so that any possibility of damage being caused to the belt is reduced.

The engaging means 76 comprises, in the preferred embodiment a series of stainless steel wire hoops that extend from either edge of the belt to leave a channel therebetween. A rail (not shown) is provided either side of the belt to reduce the likelihood of retrieved items being washed off the belt.

The conveyor belt is attached at one end to one or more pneumatic or hydraulic arms 78 that are operable to lift the end of the conveyor belt up out of the sea. The end of the belt may be lowered to any angle of up to 45°, but the normal operating angle of the belt is approximately 32°. In this way, the belt can be lifted out of the sea when it is desired to move the vessel at an increased speed.

A wheeled drive mechanism 80 is provided within the vessel and comprises, in the preferred embodiment, four close coupled driven tyred wheels that can engage and transport any items retrieved from the sea. A storage rail mechanism 82 is provided within the vessel so that the items retrieved from the sea can be stored. Figure 5 illustrates a group of trolleys which comprise one unit of the rail mechanism 82 and which are particularly suited for the storage of a buoy and submarine assembly as described herein. As shown, the rail mechanism 82 comprises a rail 84 and three trolleys 86 per unit. A first trolley 86(i) supports the buoy 5, a second trolley 86(H) supports the umbilical and a third trolley 86(iii) supports the submarine assembly 3. The trolley storage system is advantageous as it requires only a small amount of room on-board the vessel. Thus, a large number of buoys, umbilicals and submarine assemblies can be stored on board.

When used to collect buoys and submarine assemblies as described herein, the vessel is manoeuvred until the buoy is caught by the engaging means 76, whereupon the buoy is conveyed from the sea to the vessel. At the top of the conveyor belt, the buoy is lifted onto the first trolley 86(i) and the wheeled drive mechanism draws the umbilical along the channel between the engaging means up the belt. The umbilical is then looped onto the second trolley 86(ii) and as it is drawn into the vessel, so the submarine assembly is lifted from the seafloor and drawn towards the vessel 70 whereupon it will eventually be engaged by the engaging means 76 and lifted up onto the belt. The assembly will then be drawn up the belt within the vessel and then can be hung upon the third trolley 86(iii) to complete the loading process for that buoy and submarine assembly. The process can then be repeated until all of the buoys have been collected or until the vessel has reached maximum capacity, whichever should occur the earlier.

Referring to Figures 6 and 7, there is shown an example of the vessel 70 showing optional booms carrying signal generating equipment. As mentioned above, it is conceivable for the present system to be employed from a single vessel. However, to improve the operating efficiency, it is preferred that the buoys etc. are deployed from and recovered onto a first vessel, and that the signal generating means is provided on a second separate vessel. As shown in Figure 6, the vessel comprises a catamaran having a storage area

100 between the two hulls 72. The catamaran also has booms 101, the ends of which are at least 60m apart. The booms are retractable and are provided with signal generating means 102 which, in use, generate signals for detection by the submarine assemblies.. As shown in Figure 7, the conveyor belt 74 of Figure 4 is arranged between the hulls 72. In the embodiment of Figure 7, two conveyor belts are provided - but a single belt or a greater number of belts may be provided if desired. It will be understood, of course, that the invention has been described above by way of example only and that modifications may be made within the scope of the invention. It should also be noted that further preferred features of aspects of the invention are described in the attached appendix, and that the particular combination of features claimed is not limiting in that further combinations and/or permutations of features other than those specifically enumerated may be claimed. In other words, any of the features described herein (whether in the appendix or the main body of the description) may be claimed either alone, or in combination with any one or more other features described anywhere in the application.

APPENDIX

A Brief. Lavmaπ's ovei-view of the McABS projects.

It is proposed to create a new company, operating two field crews equipped with Marinised Syntron Poiyseis radio teiemetry seismic equipment.

What does this mean?

Background: Seismic Exploration:

Currently, oil companies explore for oil and gas by drilling, often very deep- and expensive -holes. This is not 'blind'; they have many tools to assist in determining where to drill. Principal among these is the seismic section, a cross section of the reflective layers of rock beiow the .surface. Generally, a change in rock formation will act as a reflective iayer- and sedimentary rocks, often many miles thick, will contain many rock changes. This is both in mateπal- limestone to sandstone, for example- or density, aggregates to siltones, etc.. The medium used to locate these reflective layers is sound- acoustics; low frequency noise created by explosives, or pneumatic sources like .high pressure tuned 'air gun arrays', which simply make a very large bang under water. In the Marine environment, Seismic is the principal tool for looldng beneath the earth's surface. The tool for Hastening to the returned reflected sounds is a series of phones buried in the ground. From these recorded returns, a picture of the sub surface is constructed, showing structures, hopefully with OH traps' (reservoirs).

The Opportunity for new technology: McABS.

The marine environment has a peculiar problem for seismic- the water medium is ideai for detecting the returning, reflected sound waves with towed a ays of hydrophones, devices that when compressed by pressure waves- the returning sound waves- generate a very smail electrical impulse. Tiiis is performed by compressing a crystal in the 'hydrophone'. The problem is only certain pressure waves can travel titrough water- if the Geophysicists require more information; they employ Geophones, which are directly coupled to the sea floor. These units empioy a magnet suspended inside a coil, which when moved creates a smail electrical current. However, a significant problem is, that aithou.gh the geophones have many advantages over the hydrophones, logistically it's a lot more difficult to deploy. .And thus more expensive.

The nature of the Marine environment - often deep, frequently hoaile, rarely quiet, and usually full of boats, ships, and fismng equipment- means care and thought is required to deploy any equipment to record the returning sound waves.

Currently, the bulk of the M.arine seismic Industry employs towed hydrophone aιτays. usually many of them, in streamers (up to 12, currently, with plans for 20, six or more Kilometres long, 50 or 100m apart, from speci ised, expensive, purpose built vessels.) The Problem:

However, a small market has developed, where Geophones are deployed, in long (currently 12 Kilometres maximum) arrays, with dual sensors every 50 m. (Dual sensors are employed, one hydrophone, one Geophone, per point receiving location, to overcome 'ghosts'^' in the received sound waves, caused by the sea surface acting as a refection layer.) This tecr-mque is cailea OBS, or Ocean Bottom Seismic' Currently world wide there are less than 1 crews, due to the hieh costs. This market couid develop hugely, if the costs- currently more than twice that of ths towed hydrophone arravs- could be reduced. The market is calling for geophone systems, (hence the expensive OBS crews), however if a superior system couid be estώlished, then the market would respond with expansion of the number of crews. The Solution:

The McABS ( Multi-component Array Bottom Seismic) is a solution to the 'stagnation' seen in the current Geophone placing technology, whereby four vessels are required. OBS requires a recording vessei, with Dynamic Positioning to hold its location, in any seas, wiiiist connected to the cabies on the sea floor via vulnerable 'jumpers' in the water column. A second vessel is required for the seismic source, to create the puises of energy, UaSuaily pneumatic air guns, sometimes dyn.aιnite. Two more vesseis are required to handle the huge lengths of heavy, expensive cables, now at > 70 .kHo.mete.rs per crew.

McABS requires no dynamically located vessel- the recorder is on the second vessei, no longer required to be hard wired, but linked via telemetry buoys. So the relocation of the recording .synem onto the source vessei removes an entire, expensive, siiip with crew, and associated duplication of effort. .An .Immediate reduction in ccst.

By eliminating the need for cabies to link the receiver -arrays together, the second cable vessel is removed. We now have a logisticaily simpler crew with only half the operating overhead, doing die same tiling!

And the other advantages:

But - its potentώly much better, because:

1. Employs 3 vari-axiai geophones and three hydrophones PER .ARRAY. A Geophysical improvement over received signals from the deep su.ύ surface obtained currently.

2. .Arrays can be varied to suit the requirement, not the cable dimensions.

3. Dragging long, heavy cables onto ships and spi ting them off the ^em every day wrecks die cables- this is no longer required! Reliability is vastly improved.

.4. Grater flexibility in marine environments- reaH.mc.aily, OBS is limited to

120 meters depm- tiiis method can go as deep as the client can pay for! hv hasn't his been done before? -

1. This telemetry buoy technology is πewiy evoived - previous systems were single channel, not appropriate to a marine, muiti component array.

2. Concern over catching the surface radio buoys, - McABS designed concepts removes this possibility.

3. .Another problem is the h.aπdling of a l.arge number of discrete buoys with arrays- again McABS has a fast, reliable solution to this. Other, more minor problems exist, but solutions for these are conπiiπed in tiύs plan.

Conclusion:

Borrorπ line of this project: A superior product, more flexibly delivered, at h^f the cost. AND with the Industries most experienced personnel. Title: Rapid Buoy Recovery Device.

1. ABST RACT. In order to safely but rapidly recover heavy, cumbersome telemetry buoys from die sea. a particular technique employing specialized equipment is required. It is essential that this operation is totally hands free, to reduce or eliminate any possible ha^rd to the Ships' crew whilst operating frequently difficult conditions.

By the use of a constantly moving mesh belt, deployed from the vessels main deck line_, parallel to the ships hull, die buoys can be 'scooped' out of the water, lifted to die ships mam deck, where buoy is safely attached to an overhead rail for stacking inside die ship.

Recovery of the Umbilical, often in lengths of greater than 30m. also needs to be hands free, this is achieved by use of conventional four ATV tyred direct dπve hydraulic wheels. Again, the cord is stacked on an overhead rail trolley.

Final item to come onboard, now lifted by die 4-vvheel puller, is the multi- component array, again lifted by the broad gap mesh conveyor system, deposited onboard onto the guides, and attached to the overhead rails.

2. Background of the Invention. Seismic Companies have to respond their customers requests for more sophisticated products, die principal amongΛ these is to deploy Geophones on the seafloor, as an alternative to towed hydrophone arrays. There are many advantages to the use of geophones instead of hydrophone arrays. Prime amongst which is the geophones ability to couple directly to the solid sea floor. Thus the bottom placed Gecphone can receive and respond to sheer waves, which do not travel d rough water and dius cannot be recorded by hydrophones. However the increased cost of the bottom placed Geophone normally precludes it being selected for use by most oil companies to survey their sectors. The majority of all marine seismic surveys are still recorded by the use of towed array of hydrophones.

Sufficient interest however in the advantages of the geophone m the marine environment. has lead to the support of a number of crews dedicated to the deployment of the Geophone. (Usually in combination with a close-coupled hydrophone, to create what is termed a 'dual sensor' phone array ) These crews are called 'Ocean Bottom Seismic^' or OBS crews, and fill an important mche m the seismic survey market.

One aspect of the OBS operation that marks it out .as difficult, is the need to frequently recover the ends of the cables deployed at sea. This is achieved by maneuvering the cable vessel as close to the surface marker buoy as possible, usually a Norwegian buoy, or a Sonardvnc ORT. an acoustically released device. Once close enough, a crewman must launch from the bow of the vessel a grapple hook, catch die rope below the buoy, and haul it onboard. The rope is then placed into a four or eight-wheeled puller, over a large diameter wheel. All this is labour intensive and can pose quite a ha.zard. particularly if die weather is rough, or die currents strong. Trapped fingers arc common whilst pulling the buoy rope over the bow.

It is also very inefficient, taking up to 10- 15 minutes to recover each buoy Evidentially, there is a requirement for a faster, safer more efficient rccovei-y method Technical features: In order to produce long periods of totally reliable service whilst working in very harsh, abrasive and frequently hostile environments, requires some over -engineering of construction and high specification materials As such, the lower roller of the conveyor belt is mounted in heavy duty, fully sealed marine roller bearings Constructed of thick wall schedule 80 stainless steel, it is perforated widi 30-ccntιmeter wide 6 centimeters deep slots to allow water to pass through with minimal resistance Diameter of 60 centimeters is required to prevent an undue bending strain on the umbilical cord connecting the surface control buoy with the Multi-component array on the sea floor, during recovery

Over the lower free wheeling roller is a wide mesh chain mail conveyor belt. This again must be designed to offer minimal resistance to the passage of water through the belt. Attached to the underside of the belt at 25 -centimeter spaces across the width, are 40-centimeter long prongs. These are stiff 'catching' prongs, to - rest the buoy and carry it up the belt to the vessel mam deck. Teflon covered side rollers on the rail sides reduce the drag on the buoy in its journey up the belt, mounted in strong Stainless I beam supports for the lower roller.

The top roller is smaller diameter than the lower, and is constantly driven. Direct drive from a hydraulic motor ensures reliability and compact operation.

The buoy is carried to die top of die roller where it is dropped onto Teflon guides. A hook from the overhead rail system is attached to the buoy, and it is earned to the rear, using the same mechanism as employed on the ski lift T bar system. The Umbilical cord is caught between rotating tyres of a four-wheel puller, and pulled onboard. The Cord is looped onto a frame below the second roller as it is spat out of the puller; tliis is retrieving the array from the seafloor Once the array is caught by the belt probes, and carried to the main deck level, the vessel can move onto the next buoy where the operation is repeated. A third trolley is employed to carry the array, which is moved into the mam deck for maintenance prior to re-deployment.

Diagram 1.

1. Coπvevor belt to 'scoop^' Buoys from the water Constructed from strong and wide mesh Stainless steel to offer minimum resisrance to the passage of water- it has to wi_thstand being driven through the water at up to 6 knots whilst still deployed

2. A ^"large Diame_ter roller freely rotates on die lower end. driven by ie large gap mesh, stainless steel chain mail. Constructed light but strong, is perforated to allow free passage of water through the roller, to reduce to a minimum possibility of damage from heavy usage.

3 Four-wheel puller to recover the umbilical cord, as it follows the buoy over the belt. The buoy is suspended above the wheel by Teflon guides above the wheels, whilst die Umbilical falls dirough the guides between the ATN tyres of the puller Recovery of the cord shoots it in ioops into a bin. which is attached to an overhead trolley

4 Probes, attached to the underside of the stainless steel mesh of the conveyor belt. Strong enough to take the weight of the buoy without being bent backwards. Located every- 25 cms across die width of the belt, in rows 2 meters apart to catch the buoy

5. Activating arm of hydraulic recovery ram. to lift the entire conveyor belt up to die main deck level when not in use. Required for high-speed transits and bad weather periods. Constructed from Stainless steei to offer maximum protection from corrosion, bearing is fully sealed.

6. Bπdge extended over side of vessei. with Storm proof windows located to allow full view of the lowered conveyor belt. Thus recovery of die buoy is remote and totally hands free, allowing maximum maneuverability of the vessei to position for the buoy scooping.

7. Trolley on overhead rail system, similar to the T bar recovery system for Sid slopes Removes the equipment to the main deck, where it can be worked before re-deployment.

8 Surface control Telemetry. Norwegian or ORT (acoustic release) buoy

9 Multi-Component buoy being recovered up the conveyor belt, pulled by the Umbilical cord being recovered by the four-wheel puller

i. Ti_tle: Multi-Component Array seafloor Seismic Instrumentation.

2. ABSTRACT: To place on die Sea .Floor devices to record returning sound waves gencra_tcα m a con_trolled manner, m order to determine die ray path from die energy source _to i c recording device, requires expensive tcciiniqucs with sophisticated dcpiovmεnt and recovery mechanisms.

By employing a much-modified six-channel radio Telemetry product in the maπne environment allows the recording from a single point on the sea floor of six discrete recording devices, with any combinauon of geophones and hydrophone. 2 meters separation of two attached but discrete transponders allows detcππinauon of geophone orientation as well as accurate location (sub meter) on die sea door of the geophone and hydrophone array. Data .recorded is stored in internal Hash memory cards until downloaded via UHF radio, located on die .surface in a control buoy. This buoy, powered by batten- and soiar panels, receives control commands from the Source Vessel. No separate recording vessel is required, the multichannel recorder being iocated on the buoy-handling vessel. An umbilical, selected to be 1.5 tunes the deepest water depth of the survey area, connects the array on die sea floor via 12-core cable, to the control buoy. Kevlar braiding of die Umbilical, with Keium Clamp artac rπcnts to the buoy and the arrav, allows the umbilical to be strong enough to lift the array from Sea floor.

3. Background of the Invention.

Maπne Seismic Ξxplorauon is currently divided into two discrete methods.

A. / Principal method is for a vessel to tow streamers coπtauuπg arrays of Hydrophones, wiiich record returned sound waves generated, usually, by a pneumauc source, either also towed behind the same vessei or a second vessel. Altiiough very -successful, and accounting for the majority of all seismic surveys recorded to date, this mediod does have some disadvantages. The largest disadvantage is die use of Hydrophones precludes die recording of sheer waves, which do not travel dιrou.eh the water medium.

Otiier disadvantages mclude die susceptibility to sea surface generated noise m poor weather conditions. Awkward navigational control of a vessel usually towing multiple suea ers. making it impossible to come to a stop, and also long tune consuming turns to prevent die towed streamers tangling. Very sophisucated acoustic and tracking mechanisms arc required to determine die exact locauon in πzύ u e of the dynamically moving arrays in die towed streamers.

B/. In response to die Oil

Industry requirement for more detailed recorded information, a second system, called Ocean Bottom Seismic (OBS. l is evolved, to piace geophones (usually in comoinauon widi Hydrophones), at die .same location on the sea floor. Vast numbers of arrays are deployed, which require to be connected to stauoπary recording vessei. to feed both power down die long - often 12 .Kilometers - cables, and record die array signals generated from sound sources. Most of die significant problems associated widi die towed streamers arc answered by the adoption of OBS systems, but other prooicms .result.

The ma_jor problem with a Boilom Cable is cost- it requires four vessels, as opposed to die one or two of towed streamer, to facilitate rccorαing. due to die rccorαmg vessel now not bemg able to tow the seismic source. The Huge amounts of cable required also require uiuiuple vessels to deploy and recover the cables.

To overcome these problems, a ilurα teciinique is required. Tliis is dic suoicπ of tins Patent.

C Raαio Tc.icmc_t.rv buoys, deployed in the aπnc or frcsn water environment, to record muiiicie ci-ai-πcis. The πumocr of vessels required is halved, unreliable caolcs arc removed, ana niuiupic com-Jiπaucπs of ecp_tioncs _/ Hvdropiioncs c::n be dcpioycα. Orientation of the Gcopnonc axis in the horizontal oianc :s requires, ana _tlus is accomplished by use of two ≤onarαvnc TΣ 7315 transponders or Digicourrc 2-110 equivalents. Technical features:

Details of the Multi-Component Array Bottom Seismic system:

Diagram 1.

Shows the surface buoy, constructed to survive impact from the recording vessel, and rough treatmen_t on recovery and deployment. A tough ABS plastic skin surrounds Polyurediane. closed cell flotauon medium. A molded anchor point on the underside is for the attachment of the Kelum gπp, (Chinese Finger) to impart forces direct from die Kevlar braid on the Umbilical to die buoy body. This dieπ prevents undue strain on the umbilical connecuon. whilst maintaining a direct pull central on the buoy vertical -txis.

Inset into the top surface of the buoy are large area solar panels, to maintain batten' life for extended periods of operation over many days. They are sufficient for Duller Northern latitudes. The buoys, in periods of non-use. have a 'sleep^' facility to preserve batter}' life. Quickly removable batteries are employed, to be changed and re-charged every time a buoy is recovered at the end of its recording period. The .Antenna is a nigged, fully aππe UHF unit, capable of witl standing some hareh treatment without damage. All connections, for the batteries, antenna and umbilical, are fully i.n-irinized bulkhead connectors.

Diagram 2. Shows detail of the Umbilical cord, used to connect the array on the sea floor with the floating conuol buoy on die surface. A fully waterbiocked 12 core cable. 16 AWG tinned cadmium Bronze 7 x 6 x 32 strand cable is used. End connections are fully maπnized bulkhead connectors, being double 0 ring sealed. Pins are gold plated to prevent corrosion from seawater when opened for maintenance on the vessel decks. Length of the Umbilical is to be 1.5 times the water depth. This will allow the cord to respond to current pulls without lifting die array from the sea floor. Excessive length will prevent the approximate location of the buoy to be known, and make navigating past the buoy without impact by the source vessel very difficult For example, in 30 meters of water, maximum, 45 meters of cord will be required. Thus for surveys in different areas, an inventory of different length cords will be required. Maximum water depth of operation is only restricted by the build specifications of die Umbilical and array units, as die surface buoy, although fully maiinized is not required to be pressure sealed. This improves reliability enormously, and extends die operating depUi of the system beyond those normally encountered in OBS surveys.

Diagram 3. Shows the detail of the array employed on the seafloor. Three Geophones. aliened in U_tree different axes, are employed. All diree geophones will be gimbaled. to remove die requirement of the array to land horizontally, not always a practical possibility. To prevent the array being moved once selded on the sea floor, and improve coupling of die Geophones with the bottom medium, a heavy, πon-magneUc, non-corrosive metal rod is molded into die array, along die axis of one of the geophones. One end of die rod has an eye, for attacliment of a small sand or Bruce anchor to also resist movement, parucuiarly in areas of strong tidal currents. A mount for the acousuc uansponder is also incorporated here. This allows accurate location of the array when it has settled on the sea floor, to better than i meter resoiuuon. ordinarily. Two hull mounted transducers on the buoy deployment, or source, vessels arc required, and d is operation is independent of die seismic operauoπ. (For Interest, seismic acoustic frequencies are in the range of 3 to 12S Hz: die transponders operate in 40 kHz frequency range.)

A spring rod. plastic covered spπng steel, is attached to the other end of die brass rod. to allow it to always be orientated in die direction of die rod. This is 2 meters long, widi a second transponder located on die far end. This second unit is required to produce a second location for the aixay. from which via established RGPS algoπduns the orientation of the rod and hence the Pππcipal array Geophone. is determined to better than ten degrees. Also located on this rod are two Hydrophones. These extra two channels are recorded to improve the signai/πoisc ratio of the final product, reduce die effect of mulliples. by combination of die signals with the opposite polaπty geophones. and improve the flexibility of the arrays usage. 1. Tough. High Visibility ABS impact resistant tough piasuc ^'skin^' for die body of the control buov Tliis is to contain die electronics and die UHF radio, protect the flotation mateπal. and offer a platform to mount die electronics, soiar paneis and die batteries. A molded eyelet on die underside of the buoy allows for attacliment of die umbilical Kelum gπp, (Chinese Finger).

2. Closed cell Polyuathene foam, to maintain buoyancy and foπn for the conuol buoy. Easily repairable on die crew if damaged.

3. Large capacity, sealed battcπes. attached to the underside of die soiar panels for quick release and replacement, extend down deep inside die buoy, to maintain die center of gravity of the buoy to be as low in d e water as possible. This will maintain an upπght oπentation at all times for die maximum range of the antenna. Spare volume above die battery is closed cell polyuathene foam, molded as part of the battery.

4. Solar paneis mounted to d e top of the buoy, with a large O ring seal undemeadi to act as die top plate and prevent seawater mgress into die buoy body. A singie cable connects the panel battery to the elecuonics box, via a fully maπnized bulkhead connector. This to expedite rapid changeout of the batteries, and maximum reliability. The Batteπes are secured directly to the underside of the panels. Attachment to die buoy body is via quick release single turn stai.rdess connectors.

5. Elecuonics: Minimum 6 Channel system, with flash memoiy, and d e latest leading edge low power UHF radio. 24 bit Delta-Sigma technology with two-way communicauoπs. The central Recording unit, located on the Buoy vessel, can remoteiy program the Buoy, coπuolling die K-Gains, complete lns umentauoπ and seismic Quality Conuol onitoπng, and customize the processing software. Single Interface cable connector for die Umbilical Cord, mounted on the top of die anodized .Aluminum case body, widi a second connection for die manne antenna. Download of the stored data is at die convenience of the Buoy vessel, being at the compleuon of the designed shooting patch array lme, whereby die buoys are recovered pπor to re-deployment at die odier side of the roiling patch.

6. Antenna. Fully marinized. nigged and flexible, built to withstand die haπh environment, accidental running over of the buoy by the survey vessels, and for maximum range. Being mounted at sea level; die ground plane effect will maximize the range attainable.

7. Reflective tape on antenna, to allow detection of die buoys at night by use of the vessel searchlights. Reflecuve tape is also bonded to die outside of the ABS plastic buoy bodies.

8. Umbilical Cord. This feeds the signals from die six phones located on die sea floor to die electronics in die conuol box, where it is stored in die flash memory. Connecuon is via a fully aπiuzed Bulkhead connector. To prevent any strain on diis connector, and prevent any turning moment of the top mounted cord tending to pull the buoy over, d e cord is attached to die eyeiet under die buoy The Cord is braided its full lengdi in Kevlar fiber, to allow the umbilical to be a strain member, and the lifting mechanism for die array on die seafloor. It is important that no strain is imparted to die conductor m the Cord.

9. Kelum gπps. or Chinese Fingers, .are used on die top and bottom of the Cord to attach. via a quick release Carabina Stainless Connector, die grip to the eyelet. This maintains die buoy in a vertical oπentation. even in poor weather, improving visibility of the buoy and die radio range. Fi_gur_e i_.The Surface control buoy^.

Fi_gu_re

10 Hydrophone 4 1, built in, pan of the 4C (four Component ) array Rated for 400m or deeper if

Industry requires.

11. Hydrophone 4 2, on flylead from array body. Attached to die spring rod claim 13 12. Hydrophone 4 3, on end of flylead. Attached to the spπng rod claim 13.

13. Spπng rod. Plasuc coated stainless spring steel, firmly attached to brass rod. claim 14, parallel.

This is a support for die acoustic transponder located on die spring rod end Length two meters.

Can be increased if required, but shorter iengdi is advantagous in on board*handhng of array.

14. Brass rod. Non metallic, non corrosive dense mateπal. Weight approxunady 10 Kg. To aid coupling with the sea-floor. To allow spπng rod to be attached parallel to die prune Geophone axis. Claim 14. Eyelet on one end for attachment of Bruce or sand anchor to prevent dragging by surface buoy in currents, and attachement for acoustic unit Claim 18. Odier end of Brass rod is extended to allow attacliment of ie Spπng rod. Claim 13.

15. Gimbaled Geophone 4\. Vertical axis, Conventional response to imparted energy from earth, opposite to diat of Hydrophone, (for flat seafloors, it's not πessisary to Gi bal this Geophone.)

16. Gimbaled Geophone 42. Hoπzoπtal axis, parallel to die Brass Rod, claim 14. 17. Gimbaled Geophone 41. Hαπzoπial axis, at πght angles to that of the Brass Rod. ciaim 14. 13. Acousuc transponder. To locate the array on die sea floor, using high frequency acoustic pinging mediods, whereby as die source or Buoy vessel passes the transponder, ranges are recorded to die uiut. Deterπunauoπ of die ..Array location is deπved by .knowing accurady the locations of the Hull uansducεr in die Vessel employed to ping the unit Multiple ranges increase die accuracy of die deπved fix.

19. Second acousuc transponder. This unit is required to determine die oπentauoπ of die Geophone arrays, required to process the imparted energy waves impinging on the Geophone. A Resolution of better dun 10 degrees is obtained with a seperauon of 2 meters.

Opuonal attachment for sand anchor, for heaw

1 9m overall when stacked.

0 8 m

Rail required 0 8 m for buoy, 1 1 m for loops and anav, = 1 9m / unit- 625 units requires 1190 m of rail, with 40 m of deck, require 32 raili 0 8 m apart Source vessel will have backup but t.άmZmά rail capacity, for backup buov coUecuon and transits, with .spares (125 of )

Convevor belt. S S. mesh with 8 inch pins to catch Buov, totally hands free This lavout is for the rnvnnnn π ιvι-τ* hunv rn αttiri._*-!

pπor to the catamaran being

Rails required; 4c anav, loops & Buoy require 1. 9m of πnl; assume working deck delivered. .Props will need

40m long, rail to be 36m long, I e. 19 arrays. This is sufficient for 3.7 Kms of laylme shrouding, as will rudders. with 200m .spacing. For 10 sq,Jαns requires 10 rails, at 400m receiver lme. Thus Jet dπve on cats will can lav 190 arrays. eliminate this concern.

If require 100 m x 400 m aπavs, require 20 rails for 380 aπavs.

Vessel loaded for 500 arrays, requires 27 rails. For this vessel needs to be 30 m working beam.

Λltemairv e is two boats, to aα as buoy vessels. Too expensive.

Soluuon: upper deck of rails I e. two decks. With powered trolley del.rve.ry between decks. Spares and damaged buovs on upper deck.

To collect Polyseis buoys from the sea, hands free, during inclement weather, and allowing fast operating speeds.

The system is a strong, stainless steel frame, 11 metres long, 1.2 meter wide. The pivot point is 1.5 meters inside the top, where the direct drive hydraulic motor is located above. This drives a coarse mesh conveyor belt, of Kevi.ar weave. This construction impaπs minimal frontal ar-a, and thus resistance, to the sea action, allowing water to flow directly tlirough the mesh, reducing the possibility of sweil damage. Attached to the underside of the mesh and projecting tlirouώ 45 cms long, are stainless steei wire loops, 9mm diameter, extending half the width of the belt. Two loops are side by side, with a gap between of 12 cms to ailow the Umbilical to trail througL These will catch the Telemetty buoys on the underside, and convey up to the 4-wheel puller on the vessel main deck.

A .rail system 1 -meter tall ejcteπds the leπ.gth of the platform, to prevent the buoy being washed off the side.

Hydraulic recovery of the piatform, for stowage whilst underway, is effected by a beam action on the lower free rotating drive pulley. A hydraulic ram located above the ships moulded side acts on the be-am, to force the piatfomi up. This keeps the ram out of the water, and prevents corrosion.

Angles of 45 degrees are available, but normal operating angle will be 32 degrees.

beftjust below mesn sea swfees.

This system replaces the Large diameter drum on a conventional Ocean Bottom seismic vessel. This drum is vun-yabie, requires manhandling of the buoys, aπα quite inefficiant.

The system composes a retractable conveyor belt which is safely stowed in very bad weather, offers little resistance to water passage, and totally hands free. The buoy is collected at the wateriine, and deposited onto the 4 wheel puller, (guides over, to sit the buoy on whisi the buoy is attached to the rail trolley and pulled .aft). The puller then recovers the umbilical cord. Booms instead of Baravanes:

Extra wide catamaran

has the solution for spread.

meters 12 meters 9 meters

S <S <G O-ϊ S

t t>el1:_

Claims

1. A submarine exploration system comprising at least one submarine assembly having at least one signal detector; and a buoy connected to said submarine assembly, said buoy having wireless communications means for transmitting said detected signals.

2. A system according to Claim 1, comprising a remote station for receiving said transmitted detected signals.

3. A system according to Claim 1 or Claim 2, comprising signal generating means.

4. A system according to Claim 3, wherein the signal generating means is mounted on a vessel which is capable of deploying said buoy and said submarine assembly.

5. A system according to Claim 3, wherein the signal generating means is mounted on a separate vessel to that which is capable of deploying said buoy and said submarine assembly.

5. A system according to any of Claims 1 to 4, wherein the submarine assembly comprises at least one hydrophone.

6. A system according to any of Claims 1 to 5, wherein the submarine assembly comprises at least one geophone.

7. A system according to Claim 5 or Claim 6, wherein the submarine assembly comprises three geophones.

8. A system according to Claim 7, wherein said submarine assembly comprises an elongate mounting arm and a first of said geophones is mounted in parallel to said arm, a second of said geophones is mounted substantially perpendicular to said arm, and a third of said geophones is mounted at right angles to said first and second geophones.

9. A system according to Claim 8, wherein said submarine assembly comprises three hydrophones mounted at spaced locations on said arm.

10. A system according to any preceding claim, wherein said submarine assembly comprises means for indicating the location of the assembly.

11. A system according to Claim 10, wherein said indicating means further indicates the alignment of the assembly.

12. A system according to Claim 10 or Claim 11, wherein said indicating means comprises a pair or transponders mounted on said assembly at spaced locations from one another.

13. A system according to any preceding claim, wherein the buoy comprises an impact resistant housing having an internal cavity sealed against water ingress; power means for powering said wireless communications means; and an antenna by means of which said signals are transmitted.

14. A system according to Claim 13, wherein the buoy comprises float means for maintaining the buoyancy of the buoy.

15. A system according to Claim 13 or Claim 14, wherein the wireless communications means comprises a UHF radio transmitter.

16. A system according to any of Claims 13 to 15, wherein the power means comprises one or more batteries.

17. A system according to any of Claims 13 to 16, wherein the power means comprises one or more solar cells forming an integral part of the housing.

18. A system according to Claim 17, wherein the solar cells form at least part of a lid that is capable of closing the internal cavity of the housing.

19. A system according to any of Claims 13 to 18, wherein the antenna is mounted on the buoy via a spring loaded mounting.

20. A system according to any of Claims 13 to 19, wherein the underside of the buoy is provided with an eyelet to which a kelum grip may be attached.

21. A system according to any of Claims 13 to 20, wherein the impact resistant housing is of tough ABS plastic.

22. A system according to Claim 14 and to any of Claims 15 to 21 when dependent on Claim 14, wherein the float means comprises closed cell polyurethane foam.

23. A system according to Claim 22, wherein the float means is integrally formed with the housing.

24. A system according to any preceding claim, comprising a submarine cable attached at one end to said wireless communications means and at the other end to the submarine assembly, the signals detected by said detecting means being passed to said transmitting means for transmission.

25. A system according to any preceding claim, wherein the wireless communications means comprises a receiver for receiving signals transmitted from a remote station.

26. A system according to Claim 25, wherein the receiver is a UHF receiver.

27. A system according to any preceding claim, wherein the submarine assembly is installed, in use. on the seabed.

28. A system according to any preceding claim, wherein the buoy is capable of floating on or near the surface.

29. A method of submarine exploration comprising: deploying at least one submarine assembly connected to a buoy; generating signals with one or more signal generators provided on said submarine assembly; detecting signals with one or more signal detectors provided on said submarine assembly; and transmitting said detected signals from said buoy.

30. A buoy for a submarine exploration system, the buoy comprising: an impact resistant housing having an internal cavity sealed against water ingress; wireless communications means provided within said housing for wireless transmission of signals to a remote station; power means for powering said wireless communications means; and an antenna by means of which said signals are transmitted to said remote station.

31. A buoy according to Claim 30, comprising float means for maintaining the buoyancy of the buoy.

32. A buoy according to Claim 30 or Claim 31, wherein the wireless communications means comprises a UHF radio transmitter.

33. A buoy according to any of Claims 30 to 32, wherein the power means comprises one or more batteries.

34. A buoy according to any of Claims 30 to 33, wherein the power means comprises one or more solar cells forming an integral part of the housing.

35. A buoy according to Claim 34, wherein the solar cells form at least part of a lid that is capable of closing the internal cavity of the housing.

36. A buoy according to any of Claims 30 to 35, wherein the antenna is mounted on the buoy via a spring loaded mounting.

37. A buoy according to any of Claims 30 to 36, wherein the underside of the buoy is provided with an eyelet to which a kelum grip may be attached.

38. A buoy according to any of Claims 30 to 37, wherein the impact resistant housing is of tough ABS plastic.

39. A buoy according to Claim 31 and to any of Claims 32 to 38 when dependent on Claim 31, wherein the float means comprises closed cell polyurethane foam.

40. A buoy according to Claim 39, wherein the float means is integrally formed with the housing.

40. A buoy according to any of Claims 30 to 31, comprising a submarine cable attached at one end to said wireless communications means and at the other end to a submarine assembly having signal detecting means, the signals detected by said detecting means being passed to said wireless communications means for transmission to said remote station.

41. A submarine sensing assembly comprising: an elongate mounting arm having one or more signal detectors connected thereto.

42. A submarine assembly according to Claim 41, comprising at least three signal detectors connected thereto, the first signal detector being aligned substantially perpendicularly to the mounting arm, the second signal detector being aligned substantially in parallel to the mounting arm, and the third signal detector being aligned substantially at right angles to the first and second signal detectors and to the mounting arm

43. A submarine assembly according to Claim 42, wherein said detectors comprise geophones.

44. A submarine assembly according to any of Claims 41 to 43, wherein the elongate mounting arm is of brass.

45. A submarine assembly according to any of Claims 41 to 44, wherein one end of the arm is provided with an eyelet to which an anchor or the like may be connected to reduce drifting of the assembly.

46. A submarine assembly according to any of Claims 41 to 45, wherein the one or more detectors are mounted on the arm via a gimbal.

47. A submarine assembly according to any of Claims 41 to 46, comprising a housing within which said detectors are provided.

48. A submarine assembly according to Claim 47, wherein the housing is provided with an eyelet to which a kelum grip or other suitable connector may be attached.

49. A submarine assembly according to Claim 48, comprising an umbilical connected at one end to the detectors of the assembly and at the other end to a buoy.

50. A submarine assembly according to Claim 49, wherein the umbilical is braided over its full length in kevlar fibre.

51. A submarine assembly according to any of Claims 41 to 50, wherein the arm is connected to a spring rod.

52. A submarine assembly according to Claim 51, wherein the spring rod is approximately 2m in length.

53. A submarine assembly according to Claim 52, wherein an acoustic transponder is provided on the end of the rod furthest from the arm.

54 A submarine assembly according to Claim 53, wherein a second acoustic transponder is provided on the other end of the submarine assembly.

55. A submarine assembly according to Claim 53 and Claim 54, wherein the acoustic transponders enable the location and alignment of the submarine assembly to be accurately determined.

56. A submarine assembly according to any of Claims 41 to 55, comprising one or more hydrophones.

57. A submarine assembly according to any of Claims 41 to 56, comprising three hydrophones.

58. A submarine assembly according to Claim 57, wherein the hydrophones are spaced from one another along the assembly.

59. A marine vessel comprising a conveyor belt that is operable to convey items from the surface to the vessel.

60. A vessel according to Claim 59, wherein the vessel is a catamaran.

61. A vessel according to Claim 59 or Claim 60, wherein conveyor belt extends from the surface, or from just below the surface, to the vessel.

62. A vessel according to any of Claims 59 to 61, wherein the conveyor belt has a coarse mesh.

63. A vessel according to any of Claims 59 to 62, wherein the conveyor belt is of kevlar.

64. A vessel according to any of Claims 59 to 63, wherein the conveyor belt is provided with engaging means that rotate with the belt and can engage with items floating at or near the surface to subsequently convey them within the vessel.

65. A vessel according to Claim 64, wherein the engaging means comprises a series of stainless steel wire hoops.

66. A vessel according to Claim 65, wherein the engaging means comprise two rows of hoops that extend from either lateral edge of the belt to leave a channel therebetween.

67. A vessel according to any of claims 59 to 66, wherein a rail is provided either side of the belt to reduce the likelihood of retrieved items being washed off the belt.

68. A vessel according to any of Claims 59 to 67, wherein the conveyor belt is attached at one end to one or more arms that are operable to move the end of the conveyor belt away from the surface.

69. A vessel according to any of Claims 59 to 68, wherein the end of the belt is lowerable to an angle of up to 45° below the horizontal.

70. A vessel according to Claim 69, wherein the end of the belt is lowered to an angle of approximately 32° below the horizontal during use.

71. A vessel according to any of Claims 59 to 70, wherein the conveyor belt extends, in use, downwardly towards the bow of the vessel.

72. A vessel according to any of Claims 59 to 71, comprising a wheeled drive mechanism provided within the vessel.

73. A vessel according to Claim 72, wherein the drive mechanism comprises four close coupled driven tyred wheels that can engage and transport any items retrieved by the conveyor belt.

73. A vessel according to any of Claims 59 to 73, wherein the vessel comprises a storage rail mechanism within the vessel so that items retrieved can be stored.

74. A vessel according to Claim 73, wherein the storage mechanism comprises a plurality of trolley units movably mounted on a rail, each trolley unit comprising a first trolley for supporting a buoy, a second trolley for supporting an umbilical and a third trolley for supporting a submarine assembly.

75. A submarine exploration system substantially as hereinbefore described with reference to the accompanying drawings.

76. A submarine assembly substantially as hereinbefore described with reference to the accompanying drawings,

77. A buoy substantially as hereinbefore described with reference to the accompanying drawings.

78. A vessel substantially as hereinbefore described with reference to the accompanying drawings.