U.S. patent application number 13/396094 was filed with the patent office on 2012-12-13 for buoyancy system.
Invention is credited to Tim LYONS.
Application Number | 20120312215 13/396094 |
Document ID | / |
Family ID | 45816044 |
Filed Date | 2012-12-13 |
United States Patent
Application |
20120312215 |
Kind Code |
A1 |
LYONS; Tim |
December 13, 2012 |
BUOYANCY SYSTEM
Abstract
The present invention provides a buoyancy system for moving an
object in a body of water. The system includes at least one
inflatable body which, when inflated, increases the buoyancy of the
object, and an inflation apparatus to inflate the at least one
inflatable body. The system also includes an activation system to
activate the inflation apparatus. Upon activation of the activation
system the inflation apparatus causes a gas to flow to the at least
one inflatable body, causing the object to move.
Inventors: |
LYONS; Tim; (Shoalwater,
AU) |
Family ID: |
45816044 |
Appl. No.: |
13/396094 |
Filed: |
February 14, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/AU2009/001599 |
Dec 9, 2009 |
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13396094 |
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Current U.S.
Class: |
114/54 |
Current CPC
Class: |
E21B 19/002 20130101;
B64D 25/18 20130101; B63C 7/10 20130101; B63G 8/14 20130101 |
Class at
Publication: |
114/54 |
International
Class: |
B63C 7/12 20060101
B63C007/12 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 14, 2009 |
AU |
2009903837 |
Claims
1. A buoyancy system for moving an object in a body of water, the
system comprises: at least one inflatable body which, when
inflated, increases the buoyancy of the object; at least one
inflation apparatus to inflate each of the at least one inflatable
body, the inflation apparatus comprises a gas generation system; an
activation system to activate each of the at least one inflation
apparatus; where upon activation of the activation system the
inflation apparatus causes a gas to be generated from the gas
generation system and flow to the at least one inflatable body,
which once inflated to the required volume enables the object to be
moved.
2. The buoyancy system according to claim 1 wherein the at least
one inflatable body is secured to the object.
3. The buoyancy system according to claim 1 wherein the at least
one inflatable body inflates external of the object.
4. The buoyancy system according to claim 1 wherein the at least
one inflatable body has a release means so that the at least one
inflatable body may be detached from the object.
5. The buoyancy system according to claim 1 wherein the at least
one inflatable body comprises at least one upper pressure relief
valve to release excess gas from the inflatable body.
6. The buoyancy system according to claim 5 wherein the pressure
relief valve is locked in a closed condition when the object has
reached the required depth.
7. The buoyancy system according to claim 1 wherein the at least
one inflatable body also comprises at least one lower pressure
relief valve located at the bottom of the inflatable body, wherein
the at least one lower pressure relief valve may vent any increases
in the pressure within the inflatable body.
8. The buoyancy system according to claim 5 wherein the pressure
relief valve has a valve piston which is biased to a closed
position, whereby pressure acting on the valve piston causes the
valve piston to move to allow the excess gas to vent from the
inflatable body, a locking means incorporated in the pressure
relief valve is released upon movement of the valve piston, such
that upon the valve piston returning to its closed position, the
locking means locks the valve in said position.
9. The buoyancy system according to claim 1 wherein the at least
one inflatable body also comprises a one way valve between the
inflation apparatus and an opening into the inflatable body.
10. The buoyancy system according to claim 1 wherein the at least
one inflatable body is at least partially made from a material
being heat resistant and having high tensile strength
properties.
11. The buoyancy system according to claim 1 wherein the inflation
apparatus comprises a regulatory apparatus to regulate the amount
of gas passing in to the at least one inflatable body.
12. The buoyancy system according to claim 11 wherein the
regulatory apparatus is hydrostatically governed whereby the
regulatory apparatus will provide the required volume of gas in
order to account for the external pressure and allow the inflatable
body to inflate to provide the desired amount of buoyancy.
13. The buoyancy system according to claim 1 wherein the inflation
apparatus also comprises a gas storage system and/or is connected
to an active gas generating system for supplying a gas.
14. The buoyancy system according to claim 13 wherein the gas
generation system comprises a gas generating medium contained
within at least one vessel, wherein the medium is an explosive,
propellant or other chemical compound which undergoes a chemical
reaction, producing a gas.
15. The buoyancy system according to claim 14 wherein a charge
activates the medium to create a gas within the at least one vessel
at pressure, the medium is activated by at least one initiator or
at least one detonator which is operably connected to the
activation system.
16. The buoyancy system according to claim 14 wherein the gas
generated from the medium is cooled prior to being delivered to the
at least one inflatable bag.
17. The buoyancy system according to claim 13 wherein the gas
storage system comprises a gas storage cylinder containing the gas,
the gas storage cylinder being in fluid communication with the at
least one inflatable body through an outlet passage, the outlet
passage has one or more pressure retaining disks to prevent the gas
leaving the gas storage cylinder, wherein each of the one or more
pressure discs may be ruptured to allow the gas to flow to the
inflatable body.
18. The buoyancy system according to claim 1 wherein the inflation
apparatus comprises a reservoir for supplying gas into the at least
one inflatable body to ensure it retains the desired inflation
during descent.
19. The buoyancy system according to claim 18 whereupon the
reservoir reaching a predetermined pressure the gas supply or gas
generators are activated to supply further gas to maintain the
pressure in the reservoir at a pressure equal or greater than the
predetermined pressure.
20. The buoyancy system according to claim 1 wherein the activation
system activates automatically when the object is at a
predetermined depth.
21. The buoyancy system according to claim 20 wherein the
activation system is hydrostatically activated when the object
reaches a predetermined depth, the automatic activation system
comprising one or more hydrostatically operated devices fitted
external of the object.
22. The buoyancy system according to claim 1 wherein the activation
system is manually operated from within and/or external the
object.
23. The buoyancy system according to claim 22 wherein the
activation system is activated by a remote operating vehicle (ROV),
the external manual activation system comprising a docking mount
external of the object to which the ROV dock.
24. A buoyancy system for raising a submerged object, such as a
submarine, mining infrastructure, towards the surface of a body of
water, the system comprises: at least one inflatable body which,
when inflated, increases the buoyancy of the submerged object; at
least one inflation apparatus to inflate the at least one
inflatable body, the inflation apparatus comprises a gas generation
system; an activation system to activate the inflation apparatus;
wherein upon activation of the activation system the gas generation
system produces a gas to inflate the at least one inflatable, which
once inflated to the required volume enables the submerged object
to move toward the surface of the body of water in which it is
submerged.
25. The buoyancy system according to claim 24 wherein the objected
is connected to a guide wire extending between the ocean floor and
surface, whereupon ascent the guide wire guides the ascent allowing
the recovery location of the equipment to be predicted.
26. A buoyancy system for lowering production infrastructure or
drilling equipment to the ocean floor, the buoyancy system being
adapted to be connected to the equipment, the system comprises: at
least one inflatable body which, when inflated, increases the
buoyancy of the equipment; at least one inflation apparatus to
inflate the at least one inflatable body, the inflation apparatus
comprises a gas generation system which produces a gas for
inflation; an activation system to activate the inflation
apparatus; wherein upon activation of the activation system the
inflation apparatus causes the at least one inflatable body to
inflate, partly offsetting the weight of the equipment and
controlling the rate of descent towards the ocean floor.
27. The buoyancy system according to claim 26 wherein the system
comprises a reservoir which contains a gas, the reservoir supplying
gas into the at least one inflatable body.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to a buoyancy system
for raising or lowering objects within a body of water.
[0002] In one application of the invention the buoyancy system is
designed to raise malfunctioning or damaged objects, such as
submarines and aircraft, from a depth, and/or to maintain them at
the surface.
[0003] In another application of the invention the buoyancy system
is designed to raise and/or lower objects from deep water enabling
them to be raised and recovered at the surface of the water, or
lowered into position. The object includes submerged ocean floor
infrastructure such as sub-sea trees, manifolds and platform
anchors.
BACKGROUND ART
[0004] There are inherent difficulties associated with operations
conducted in deep water. These problems are typically associated
with the increasing pressure encountered at increased depths, as
well as the weight of infrastructure, such as cables, which
increase the deeper the operations are conducted.
[0005] At increased depths, the recovery of an object is
increasingly difficult. This has been highlighted by several marine
accidents in which rescue equipment was not available for
situations in which a damaged submarine or aircraft was submerged
in water beyond a certain depth. As a result, these accidents have
resulted in fatalities.
[0006] Submarine escape and rescue/abandonment safety technology
has evolved over the last few decades. The first generation
consisted of a means of escape, which saw submarines being fitted
with escape tower/hatches, and specially designed escape suits that
would provide an escaping Submariner with both buoyancy and
breathing air to reach the surface. This technique was, and indeed
still is, limited by the depth at which the vessel lies. The second
generation consisted of rescue using a submersible or rescue bell.
This significantly increased the depth at which personnel can be
extracted from a submarine and is also much safer than using escape
suits.
[0007] However, both of these methods have significant limitations.
If the submarine malfunctions or is damaged when operating in water
deeper than its collapse/crush depth, then the current escape or
rescue methods cannot be employed to save the occupants. Moreover,
it takes many days to affect a rescue. During this time an increase
in the internal pressure of the submarine, the consumption of vital
survival stores (oxygen candles, carbon dioxide absorption devices,
etc) and the deterioration and contamination of the atmosphere
sustaining life (hydrogen sulphide, chlorine gas, etc) could be
fatal.
[0008] Another industry in which operations are increasingly
occurring at greater depths is the oil and gas industry. In this
industry equipment is frequently employed on the ocean floor for a
number of varied reasons and functions. The offshore oil and gas
industry use equipment on the sea floor to extract fossil fuels and
supply them to surface platforms and oil rigs. As the reservoirs of
oil and natural gas at relatively shallow depths are consumed
exploration for more reserves has moved into deeper water.
[0009] Positioning and recovering heavy equipment from the ocean
floor is an expensive process that requires significant assets.
Currently, equipment used on the ocean floor is positioned and
later recovered using a high tensile wire and a winch located on a
relatively large dynamically positioning vessel. However, this
method is limited to certain depths depending on the recovery
equipment's respective capability. As the depth of water increases,
so too does the challenges and cost of positioning and later
recovering such equipment.
[0010] The preceding discussion of the background to the invention
is intended only to facilitate an understanding of the present
invention. It should be appreciated that the discussion is not an
acknowledgment or admission that any of the material referred to
was part of the common general knowledge as at the priority date of
the application.
SUMMARY OF INVENTION
[0011] It is an object of this invention to provide a buoyancy
system which overcomes at least one of the problems of the prior
art, or at least provides a useful alternative.
[0012] The present invention provides a buoyancy system for moving
an object in a body of water, the system comprises:
[0013] at least one inflatable body which, when inflated, increases
the buoyancy of the object;
[0014] an inflation apparatus to inflate the at least one
inflatable body;
[0015] an activation system to activate the inflation
apparatus;
[0016] where upon activation of the activation system the inflation
apparatus causes a gas to flow to the at least one inflatable body,
which once inflated to the required volume enables the object to be
moved.
[0017] Preferably the buoyancy system is adapted to move the object
in a substantially vertical orientation. The buoyancy system may be
adapted to cause the object to ascend or descend. When the buoyancy
system is used in operations where the object descends, the system
provides a means to control the descent process.
[0018] The at least one inflatable body may be secured to the
object. Preferably a shock absorbing device extends between the at
least one inflatable body and the object. The shock absorbing
device will ensure that the object ascent, particularly the initial
and end stages, is relatively smooth.
[0019] Upon inflation each inflatable body preferably inflates
external of the object.
[0020] The at least one inflatable body may have a release means so
that the at least one inflatable body may be detached from the
object. The release means may be operated if the buoyancy system is
unintentionally activated.
[0021] The at least one inflatable body may comprise at least one
upper pressure relief valve to release excess gas from the
inflatable body. The requirement to release excess gas may be as a
result of excess gas generated by the inflation apparatus, or may
result from the expansion of the volume of gas in the inflatable
body as the object ascends and the pressure exerted on the
inflatable body from the body of water decreases.
[0022] Once the object has reached the required depth the pressure
relief valve may lock closed to ensure the inflatable body remains
inflated. This will retain the object at the desired level.
[0023] The at least one inflatable body may also comprise at least
one lower pressure relief valve located at the bottom of the
inflatable body. The at least one lower pressure relief valve may
vent any increases in the pressure within the inflatable body once
the at least one upper pressure relief valve is locked. This will
prevent the at least one inflatable body over inflating and
possibly rupturing.
[0024] The pressure relief valve may have a valve piston which is
biased to a closed position. As the pressure against an external
surface of the valve piston increases, the valve piston moves to
allow the excess gas to vent from the inflatable body. Upon the
initial movement of the valve piston, a locking means is released
such that upon the valve piston returning to its closed position,
the locking means locks the valve in said position.
[0025] The at least one inflatable body may also comprise a one way
valve between the inflation apparatus and an opening into the
inflatable body. This will prevent the gas delivered into the
inflatable body returning to the inflation apparatus.
[0026] In one aspect of the invention the at least one inflatable
body is secured to a winch, whereby the winch feeds line out to the
at least one inflatable body. This would allow the object to
descend whilst the at least one inflatable body remains on the
surface. When the object is required/able to ascend the winch is
activated and the object moves upwardly. Similarly, the winch can
be used to lower the object to a greater depth should the weather
on the surface be poor, or to allow for controlled positioning of
the object on the ocean floor.
[0027] Preferably the at least one inflatable body is made from a
material being heat resistant and having high tensile strength
properties. An inner layer of the at least one inflatable body may
be made from a material which is heat resistant and has high
tensile strength properties Preferably the inflatable body is in
the form of an inflatable bag.
[0028] Preferably the buoyancy system comprises a plurality of
inflatable bodies.
[0029] Preferably the plurality of inflatable bodies is positioned
to ensure the object is raised or lowered in a desired
orientation.
[0030] Preferably the buoyancy system also comprises control means
to maintain the object at a certain level, such as at the surface
of the water. Once inflated the inflatable body may remain inflated
for a predetermined period of time.
[0031] Preferably the buoyancy system comprises an inflation
apparatus for each inflatable body.
[0032] The inflation apparatus may comprise a regulatory apparatus
to regulate the amount of gas passing in to the at least one
inflatable body.
[0033] In one aspect of the invention the regulatory apparatus may
be hydrostatically governed whereby the regulatory apparatus will
provide the required volume of gas in order to account for the
external pressure and allow the inflatable body to inflate to
provide the desired amount of buoyancy. As the pressure exerted
upon the object increases the deeper the object travels, the
pressure required to inflate the inflatable body also
increases.
[0034] The regulatory apparatus may comprise hydrostatic pressure
sensors.
[0035] The inflation apparatus may comprise a gas generation
system, a gas storage system or it may be connected to an active
gas generating system, or a combination of these systems.
[0036] The gas generation system may comprises a gas generating
medium such as for example an explosive, propellant or other
chemical compound contained within at least one vessel, whereby a
charge activates the medium, creating a gas within the at least one
vessel at pressure. The at least one vessel may have a series of
passages and/or baffles located therein between the medium and a
vessel outlet, whereby the gas generated by the medium passes
through the passages before exiting the at least one vessel. This
will ensure the vessel outlet is not exposed to the initial force
of the medium as it generates gas.
[0037] The medium may be activated by an initiator or a detonator
which is operably connected to the activation system. The gas
generation system may comprise more than one initiator or detonator
in the event that one or more of the initiators or detonators does
not function correctly.
[0038] Preferably the molecular weight of the generated gas is
closely matched to that of air.
[0039] Preferably the vessel outlet is connected to a gas delivery
regulator so that the gas delivered to the inflatable body is
delivered at the desired pressure.
[0040] Preferably the gas generated from the medium is cooled prior
to being delivered to the at least one inflatable bag.
[0041] The inflation apparatus may also comprise a reservoir. When
the object is descending, the reservoir may supply gas into the at
least one inflatable body to ensure it retains the desired
inflation, controlling the rate of descent and maintaining the
weight, or negative buoyancy of the object. Preferably when the
reservoir reaches a predetermined pressure the gas supply or gas
generators are activated to supply further gas.
[0042] In this application, the buoyancy system might be attached
to a lowering or guiding wire, whereby the buoyancy system removes
the vast majority of the weight or negative buoyancy to allow the
object to be easily and accurately positioned on the ocean floor.
Previously, the capacity of the cable would limit the allowable
weight of the object being placed on the ocean floor at one time.
In those applications in which the buoyancy system is used, the
weight of the object may be significantly more as the buoyancy
system would alleviate the weight burden which would otherwise be
required to be restrained by the cable.
[0043] Once at the surface, the at least one inflatable body may be
flushed through with a supplied gas to dilute and/or remove the gas
that was generated during the gas generation process. This function
may be activated automatically and comprise of hydrostatic sensors
or be activated manually or remotely. This will ensure any toxic
gas has been discharged from the inflatable body prior to a
recovery unit collecting the object.
[0044] The gas storage system may comprise a gas storage cylinder
containing the gas. Preferably the gas storage cylinder is in fluid
communication with the at least one inflatable body through an
outlet passage. The outlet passage may have one or more pressure
retaining disks to prevent the gas leaving the gas storage
cylinder. Each pressure disk may be connected to a detonator. Each
detonator may be operably connected to the activation system.
[0045] The active gas generating system may incorporate a gas
supply external of the buoyancy system. Where the object is a
submarine, this gas supply may be the compressed air produced for
submarine operation. The activation system may comprise a cross
valve which fluidly connects the buoyancy system with the gas
supply.
[0046] The inflation apparatus may comprise at least one
hydrostatic sensor or pressure relief valve which is adapted to
discontinue the delivery of gas to the at least one inflatable body
once ascent has commenced. Once the ascent has commenced the
inflatable body will continue to inflate even if there was no more
gas being provided to the inflatable body as the gas inside the
inflatable body expands as the external pressure reduces.
[0047] The activation system may be activated in a variety of ways,
largely dictated by the particular application. The buoyancy system
may incorporate a plurality of activation systems. This is
particularly important in applications relating to submarines and
aircraft as it will ensure the buoyancy system can be activated
regardless of the situation.
[0048] The activation system may be adapted to activate
automatically when the object is at a predetermined depth. Such an
application may occur when a submarine is damaged and is unable to
return to the surface, or when an aircraft lands in water.
[0049] The activation system may be hydrostatically activated when
the object reaches a predetermined depth. The automatic activation
system may comprise one or more hydrostatically operated devices
fitted external of the object. In the case of a submarine these
devices may be located external to the pressure hull.
[0050] The hydrostatically operated device may comprise a
substantially sealed unit having an exposed face with a series of
perforations therein. The exposed face may be adjacent a first
plate. The first plate may be biased into a normal condition
whereby it is in spaced relation to a second plate. As the
hydrostatic pressure increases, the pressure acting through the
series of perforations causes the first plate to move towards the
second plate. As the hydrostatic pressure increases further the
first plate engages the second plate, completing a circuit to
activate the activation system.
[0051] The activation system may comprise an override mechanism so
that the automatic operation of the activation system can be
disabled should it be required that the object descend below the
predetermined depth.
[0052] The activation system may be acoustically operated.
[0053] In those arrangements in which the buoyancy system is fitted
to a submarine, the activation system may be incorporated into the
submarine's emergency blow/surface system.
[0054] The activation system may be manually operated.
[0055] Also in those instances where the object is a submarine or
similar vessel in which an operator may be contained, the
activation system may be internally activated from within the
object.
[0056] The internal manual activation system may comprise a control
panel within the submarine. The control panel may comprise a prime
button to prime the activation system and an initiate button to
activate the activation system. The control panel may also comprise
a continuity button to check the integrity of the activation system
and to commence the sequence of activating the activation system
from the control panel. This is to ensure the buoyancy system is
not accidentally activated.
[0057] The control panel may also comprise the release means to
release the at least one inflatable body.
[0058] The manual activation system may also be externally
activated by a remote operating vehicle (ROV). The external manual
activation system may comprise a docking mount external of the
object to which the ROV may dock. The ROV may be adapted to move
the docking mount from a normal condition to an engaged condition
wherein the activation system is activated. The external manual
activation system may be adapted such that a unique key is required
to access the system.
[0059] Preferably once the external manual activation system is
activated the at least one inflatable body has a delayed inflation
sequence to provide ample time for the ROV to disengage and move
away from the object.
[0060] The buoyancy system may be powered from a generated power
supply or from a battery pack.
[0061] The object may have a plurality of buoyancy systems. The
activation system of each of the plurality of buoyancy systems may
be synchronised to activate simultaneously or within a prescribed
time of each other.
[0062] Preferably the buoyancy system incorporates a locating
beacon, such as an EPIRB, which is activated when the buoyancy
system is activated. The locating beacon may be connected to the at
least one inflatable body.
[0063] The buoyancy system may also comprise a propulsion means,
whereby the propulsion means may be used to move, direct or guide
the object in a variety of directions. Gas may be used to operate
the propulsion means. The gas may be provided by the gas generation
process.
[0064] In one application of the invention the object is a
submarine. Preferably the buoyancy system does not substantially
affect the acoustic characteristics or fluid dynamics of the
submarine. The buoyancy system may be substantially contained
within the submarine's casing until it is activated. The buoyancy
system may be substantially contained between the submarines casing
and pressure hull. The buoyancy system may be sealed in a recess
extending from the casing to the pressure hull. The recess may have
a cover there across. The cover may be released from the recess
when the activation system is activated.
[0065] In another application of the invention the object is an
aircraft, such as a helicopter or aeroplane. In these applications
there may be a plurality of buoyancy systems. Each buoyancy system
may be strategically placed to ensure the aircraft is raised or
remains in a desired position.
[0066] In another application of the invention the object is a
diving suit or ROV. In the case of the ROV, the ROV may comprise
means to disengage from its connection to a surface vessel.
[0067] In another application of the invention the object is a
decompression chamber.
[0068] In a further application of the invention the object is
production infrastructure or drilling equipment, including sub-sea
trees, manifolds, and booster pumps. In such an application the
buoyancy system may also comprise at least one guide wire extending
from the water surface to the ocean floor. The guide wire provides
a steadying line to control the object's ascent and predict its
surfacing position.
[0069] The buoyancy system may also comprise at least one lifting
strop secured to the object. This will allow the object to be
recovered upon reaching the surface. The strop may be positively
buoyant. This will ensure the strop remains in a vertical
orientation for recovery.
[0070] When raising a sub-sea manifold from the ocean floor, other
subsea infrastructure, pipes, cables etc are disconnected and the
buoyancy system attached to the object's hard eye/lifting point
prior to activating the buoyancy system.
[0071] This invention provides the next generation in deepwater
heavy sub-sea recovery, salvage and installation. This new
generation of deep water recovery consists of a concept of
`floating` the object to the surface regardless of the depth of
water, to allow a surface vessel to recover the object inboard or
tow it to a nearby port. It also allows for the controlled descent
and installation of the object on the ocean floor.
[0072] The present invention further provides a buoyancy system for
raising a submerged object towards the surface of a body of water,
the system comprises:
[0073] at least one inflatable body which, when inflated, increases
the buoyancy of the submerged object;
[0074] an inflation apparatus to inflate the at least one
inflatable body;
[0075] an activation system to activate the inflation
apparatus;
[0076] wherein upon activation of the activation system the
inflation apparatus inflates the at least one inflatable body to
inflate, which once inflated to the required volume enables the
submerged object to move toward the surface of the body of water in
which it is submerged.
[0077] The present invention further provides a buoyancy system for
raising a submarine to the surface of a body of water, the system
comprises:
[0078] at least one inflatable body which, when inflated, increases
the buoyancy of the submerged object;
[0079] an inflation apparatus to inflate the at least one
inflatable body;
[0080] an activation system to activate the inflation
apparatus;
[0081] wherein upon activation of the activation system the
inflation apparatus causes the at least one inflatable body to
inflate which once inflated to the required volume enables the
submarine to move toward the surface of the body of water in which
it is submerged.
[0082] Preferably the buoyancy system comprises means to maintain
the submarine at the surface a sufficient time to allow the
Submariners to escape.
[0083] The present invention provides a buoyancy system for raising
production infrastructure or drilling equipment from the ocean
floor for recovery, the buoyancy system being adapted to be
connected to the equipment, the system comprises:
[0084] at least one inflatable body which, when inflated, increases
the buoyancy of the equipment;
[0085] an inflation apparatus to inflate the at least one
inflatable body;
[0086] an activation system to activate the inflation
apparatus;
[0087] wherein upon activation of the activation system the
inflation apparatus causes the at least one inflatable body to
inflate which once inflated to the required volume enables the
equipment to move toward the surface of the body of water in which
it is submerged.
[0088] The buoyancy system may be incorporated in a cradle which is
adapted to be secured to the equipment. The cradle may be
positively buoyant such that when it is attached to the equipment
the buoyancy system remains in a desired orientation. The cradle
may be connected to the equipment prior to the equipment being
returned to the surface.
[0089] In such an operation a strop may be connected to the
equipment to assist the recovery operation.
[0090] Also, the equipment may be connected to a guide wire
extending between the ocean floor and surface, whereupon ascent the
guide wire guides the ascent allowing the recovery location of the
equipment to be predicted.
[0091] The equipment may remain below the surface until a vessel
can attach a crane to the strop in order to lift the equipment from
the ocean or to tow the object to a port with cranage
facilities.
[0092] The present invention provides a buoyancy system for
lowering production infrastructure or drilling equipment to the
ocean floor, the buoyancy system being adapted to be connected to
the equipment, the system comprises:
[0093] at least one inflatable body which, when inflated, increases
the buoyancy of the equipment;
[0094] an inflation apparatus to inflate the at least one
inflatable body;
[0095] an activation system to activate the inflation
apparatus;
[0096] wherein upon activation of the activation system the
inflation apparatus causes the at least one inflatable body to
inflate, partly offsetting the weight of the equipment and
controlling the rate of descent towards the ocean floor.
[0097] Preferably the system comprises a reservoir which contains a
gas, the reservoir supplying gas into the at least one inflatable
body.
[0098] When moving the equipment to the ocean floor the equipment
is lifted into the water or towed floating on the surface to the
deployment position whereby the at least one inflatable body is
fully inflated and, if fitted, the reservoir pressurised. Upon
descent the activation system will activate the inflation apparatus
causing the at least one inflatable body to remain inflated
whereupon the object is more easily and accurately moved toward the
ocean floor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0099] The invention will be better understood by reference to the
following description of several specific embodiments thereof as
shown in the accompanying drawings in which:
[0100] FIG. 1 is a view of a submarine at the bottom of the ocean
floor having a first embodiment of a buoyancy system according to
the invention installed thereon;
[0101] FIG. 2 is a view similar to FIG. 1 but with the buoyancy
system deployed;
[0102] FIG. 3 is a schematic of the buoyancy system as installed on
the submarine;
[0103] FIG. 4 is a schematic of a buoyancy system according to a
second embodiment;
[0104] FIG. 5a, b is a schematic of an activation system of the
buoyancy system;
[0105] FIG. 6a, b is a plan and side cross sectional view of a
hydrostatic sensor of the buoyancy system;
[0106] FIG. 7 is a cross sectional schematic view of a gas
generation system of an inflatable apparatus of the buoyancy
system;
[0107] FIG. 8 is a cross sectional schematic view of a gas storage
system of the inflatable apparatus of the buoyancy system;
[0108] FIG. 9a, b is a plan view and side view of an inflatable bag
of the buoyancy system in an inflated condition;
[0109] FIG. 10 is a cross sectional view of a pressure relief
valve;
[0110] FIG. 11 is a schematic view of an inflatable bag and
associated vessels according to the second embodiment shown in FIG.
4;
[0111] FIG. 12 is a schematic view of a buoyancy system according
to a third embodiment of the invention;
[0112] FIG. 13 is a schematic view of a buoyancy system according
to a fourth embodiment of the invention;
[0113] FIG. 14 is a schematic view of a buoyancy system according
to a fifth embodiment of the invention as fitted to a
helicopter;
[0114] FIG. 15 is a schematic view of a buoyancy system according
to a sixth embodiment of the invention as fitted to an aeroplane;
and
[0115] FIG. 16 is a schematic view of a buoyancy system according
to a seventh embodiment of the invention as fitted to a refuge
chamber.
[0116] FIG. 17 is a schematic plan view of a buoyancy system
according to an eighth embodiment of the invention for recovery of
equipment from the ocean floor;
[0117] FIG. 18 is a view similar to FIG. 17 but with an upper level
removed;
[0118] FIG. 19 is a side view of FIG. 17;
[0119] FIG. 20 is a schematic view of the buoyancy system of FIGS.
17 to 19 shown in two stages of recovery of equipment from the
ocean floor;
[0120] FIG. 21 is a schematic side view of a buoyancy system
according to a ninth embodiment of the invention, the buoyancy
system is connected to an object and is adapted to lower the object
to the ocean floor;
[0121] FIG. 22 is a schematic plan view of FIG. 21 without the
inflatable bodies shown;
[0122] FIG. 23a, b are schematic views of alternate ways the
buoyancy system of FIG. 21 may be deployed on the ocean floor.
BEST MODE(S) FOR CARRYING OUT THE INVENTION
[0123] The present invention has many applications across numerous
industries. Certainly many more applications are also possible and
these will come to light in the future, particularly owing to the
human quest to explore the ocean depths.
[0124] Outlined below are several applications across several
different industries. The majority of the below embodiments discuss
applications in which a submerged object is raised towards the
ocean's surface. However, the invention also has applications in
controlled descent of objects to the ocean floor, maintaining an
object at a required depth and in propelling objects through the
ocean.
[0125] The invention according to the various embodiments is in the
form of a buoyancy system 11 for either raising an object 12
towards the surface 15 of a body of water, to lower the object 12
towards the ocean floor 14, or for maintaining it at the surface 15
or at a desired depth.
[0126] The buoyancy system 11 comprises a combination of one or
more inflatable bodies 16, one or more inflation apparatuses 19 and
one or more activation systems 21. In different applications and
circumstances the buoyancy system 11 is configured to incorporate
the required quantity and configuration of the aforementioned
components.
[0127] Referring to FIGS. 1 and 3, the invention according to a
first embodiment is in the form of a buoyancy system 11 fitted to a
submarine 13. FIG. 1 shows the submarine 13 in a position on the
ocean floor 14. This may occur when the submarine 13 malfunctions
or has been damaged. The present invention would allow the
submarine 13 shown in FIG. 1 to be readily returned to the surface
15 by activation of the buoyancy system 11.
[0128] FIG. 2 shows the submarine 13 after the buoyancy system 11
has been activated and the plurality of inflatable bodies 16, in
the form of inflatable bags 17, have been caused to deploy. As
shown, the submarine 13 is raised to the surface 15 in an upright
position, allowing personnel to escape the submarine 13.
[0129] Submarines 13 are typically constructed to have a pressure
hull 81 and an outer casing 83 towards the top of the vessel,
wherein the two are spaced apart. This spacing provides an area in
which the inflatable bags 17 may be stored in modules 18. It also
permits the buoyancy system 11 to be fitted to a submarine without
negatively affecting the fluid dynamics or acoustic characteristics
of the submarine 13.
[0130] For submarines 13 without the outer casing 83, inflatable
bags 17 may be stored in modules 18, engineered & incorporated
into the pressure hull 81.
[0131] The components of the buoyancy system 11 according to this
embodiment are best shown in FIG. 3.
[0132] The buoyancy system 11 comprises an inflatable apparatus 19,
which in this embodiment, is provided by an active gas generating
system 23 whereby the gas to inflate the inflatable bags 17 is
provided by a gas supply 25 external of the buoyancy system 11. The
external gas supply 25 is provided by the submarines internal air
supply 27.
[0133] The inflatable apparatus 19 is activated by an activation
system 21. The activation system 21 in this embodiment includes a
manual external activation system 21a, a manual internal activation
system 21b and an automatic activation system 21c. This provides
multiple means to activate the buoyancy system 12, ensuring the
submarine 13 may be raised to the surface regardless of the
circumstances. Obviously other applications of the buoyancy system
may only require one of these activation systems.
[0134] FIG. 5 best illustrates the components of the activation
system 21 utilised in this embodiment.
[0135] The manual external activation system 21a may be operated by
a remote operating vehicle (ROV), not shown. The ROV is adapted to
engage a docking mount 29 through which the activation system 21
can be activated.
[0136] The manual internal activation system 21b may be operated
from within the submarine 13 at one of three control panels 31.
[0137] The automatic activation system 21c comprises a hydrostatic
operated device 33 fitted external the pressure hull 81. In this
embodiment there are six hydrostatic operated devices 49 secured to
the pressure hull 81.
[0138] Each hydrostatic operated device 49 comprises a
substantially sealed unit having an exposed face 51 with a series
of perforations 53 therein, as shown in FIG. 6a. The exposed face
51 is adjacent a first plate 55 as shown in FIG. 6b. The first
plate 55 is biased away from a second plate 57 by a spring 59 such
that in a normal condition the first plate 55 and second plate 57
are in spaced apart relation.
[0139] As the submarine 13 reaches a predetermined depth, the
pressure acting through the perforations 53 causes the first plate
55 to move toward the second plate 57 until a contact brush 61a on
the underside of the first plate 55 engages a contact brush 61 b on
the upper side of the second plate 57. This completes a circuit
resulting in activation of the inflatable apparatus 19, which leads
to deployment of the inflatable bags 17.
[0140] Considering the external manual activation system 21a as
shown in FIG. 5, the external manual activation system 21a
comprises the docking mount 29 having a nut 69 adapted to be
rotated by an ROV. The nut 69 is threadingly received in a housing
71 of the docking mount 29. The nut 69 is uniquely configured such
that only an ROV with a correctly configured arm is able to operate
the nut 69. The nut 69 can be removed from the housing 71 to allow
the ROV to access an activation screw 73, which is also threadingly
received in the housing 71. Upon turning the activation screw 73 it
engages an activation plate 75. Upon engagement therewith a circuit
is completed and the activation system 21 activates the inflation
apparatus 19. In order to allow the ROV to disengage and move away
from the submarine 13, there will be a delay before the inflatable
bags 17 inflate and the submarine 13 moves upwardly.
[0141] Considering the internal manual activation system 21b as
shown in FIG. 5, the control panel 31 comprises a prime button 77
to prime the activation system and an initiate button 79 to
activate the activation system. The control panel 31 also comprises
a continuity button 85 to check the integrity of the activation
system 21 and to commence the sequence of activating the activation
system 21b from the control panel 31.
[0142] The control panel 31 also comprises the release means 87 to
release the inflatable bags 17 upon accidental activation of the
buoyancy system 11.
[0143] The control panel 31 also comprises an override switch 89
which can be used to override the automatic activation system 21c
as may be required should the submarine be required to go below the
predetermined depth.
[0144] The inflatable bag 17 in an inflated state is best shown in
FIGS. 9a, b. Each inflatable bag 17 comprises four upper pressure
relief valves 91 designed to release excess gas from the inflatable
bag 17, as well as the excess volume of gas generated as the
submarine 13 ascends and the pressure exerted on the inflatable bag
17 from the body of water decreases. Once the submarine 13 has been
raised to the required depth the pressure relief valve 91 locks,
preventing any further gas from passing therethrough to ensure the
inflatable bag 17 remains inflated.
[0145] The inflatable bag 17 also comprises two lower pressure
relief valves 93 located in the lower region of the inflatable bag
17. The lower pressure relief valves 93 vent any increase in the
pressure within the inflatable body once the upper pressure relief
valves 91 lock.
[0146] Referring to FIG. 10, each pressure relief valve 91, has a
valve piston 95 biased to a closed position. As the pressure
against an external surface 97 of the valve piston 95 increases
from the pressure within the inflatable bag 17 the valve piston 95
moves to allow the excess gas to vent from the inflatable bag 17
via the relief valve 91. Upon the initial movement of the valve
piston 95, a locking means 99 is released whereby, upon the valve
piston 95 returning to its closed position, the valve means 99
locks the valve piston 95 in said position.
[0147] Each inflatable bag 17 also comprises a one way valve 101
between the inflation apparatus 19 and an opening 103 of the
inflatable bag 17. This will prevent the gas delivered into the
inflatable bag 17 from returning to the inflation apparatus 19.
[0148] Each inflatable bag 17 also incorporates an EPIRB 105 which
is activated when the bag 17 is inflated.
[0149] If the buoyancy system 11 is require to be operated, the
activation system 21 will either be activated automatically, or
manually from external or internal of the submarine 13. Upon
activation the inflation apparatus 19 is activated to divert gas
from the gas supply 25 external from the buoyancy system 11. The
gas is used to inflate the bags 17 until sufficient lift is created
to raise the submarine 13 to the surface 15.
[0150] A second embodiment of the invention is shown in FIG. 4.
This embodiment is very similar to that of the first embodiment and
so like components will be similarly numbered. This embodiment
builds on the first embodiment in that the inflation apparatus 19
of the buoyancy system 11 now also comprises a gas generating
system 35 and a regulatory apparatus 43. In this embodiment the
buoyancy system 11 does not rely solely on the supply of gas from
the submarine 13.
[0151] In this embodiment the gas generating system 35 comprises a
set of six vessels 37 for each inflatable bag 17, as shown in FIG.
11. Each vessel 37 is connected to a hydrostatic operated device 49
and is associated with the regulatory apparatus 43 to regulate the
amount of gas passing in to the inflatable bags 17, taken into
account the depth of the submarine 13.
[0152] Referring to FIG. 7 each vessel contains a gas generating
medium 39, such as an explosive, propellant or other chemical
compound which, upon detonation and/or activation, creates a gas.
This gas is channelled through the outlet 41 of the vessel 37 to
fill the inflatable bag 17. The gas may be cooled before entering
the inflatable bag 17.
[0153] The regulatory apparatus 43 is located upstream from the
outlet 41. In order to shield the regulatory apparatus 43 from the
force of the rapid gas generation a series of passages/baffles 45
are located between the medium 39 and outlet 41. These passages 45
cause the force of the rapid gas generation to pass along a longer
path, dampening the full effect of the explosion and rapid increase
in pressure.
[0154] The medium 39 is ignited by an initiator or detonator 47
connected to the activation system 21. FIG. 7 shows the medium 39
as having three detonators 47. This provides back up should one or
two of the detonators 47 malfunction.
[0155] As shown in FIG. 11 each inflatable bag 17 is secured to the
submarine 13 at a mounting point 63 which is secured to the
pressure hull 81. The inflatable bag 17 and vessels 37 are located
in the module 18. The module 18 has a cover 65 which is released
upon removal of pins 67. These pins 67 are removed by detonation
when the activation system 21 is activated.
[0156] The deployment of the inflatable bags 17 in this embodiment
closely follow that as described for the first embodiment.
[0157] According to a third embodiment of the invention the
inflation apparatus 19 comprises a gas storage system 107. This
embodiment is very similar to that of the second embodiment and so
like components will be similarly numbered. However, in this
embodiment, rather than generate gas via medium 39, the gas is
stored in a high pressure gas cylinder 109, as shown in FIG. 8.
[0158] In this embodiment the gas cylinder 109 of the gas storage
system 107 has an outlet 111 which is in fluid communication with
the inflatable bag 17. The gas is retained in the cylinder 109 by
three retaining disks 113. Each disk 113 is connected to a
detonator 115 which, when activated through the activation system
21 causes the disks 113 to rupture to allow the gas to pass to the
bag 17. A further detonator 115a is positioned such that its charge
is directed to the face of the disks 113. This will ensure the
disks 113 are ruptured and the gas is able to pass through.
[0159] FIG. 12 illustrates the configuration of the module 18 for
storing the inflatable bags 17 according to this third
embodiment.
[0160] A fourth embodiment of the invention is shown in FIG. 13.
This embodiment has an inflatable apparatus 19 comprising a hybrid
system incorporating the gas generation system 35 and gas storage
system 107. FIG. 13 represents how the inflatable apparatus 13 and
inflatable bag 17 of this embodiment would be configured in a
module 18.
[0161] In a fifth embodiment of the invention, as shown in FIG. 14,
four individual buoyancy systems 211 are strategically placed on a
helicopter 213. In this embodiment the inflatable apparatus 19 is
in the form of a gas generation system 35, whilst the activation
means is in the form of an automatic activation system 21c and a
manual internal activation system 21b.
[0162] FIG. 15 shows a sixth embodiment of the invention. This
embodiment is similar to the fifth embodiment but instead of
relating to a helicopter it is in relation to an aircraft 223.
[0163] In a seventh embodiment of the invention, as shown in FIG.
16, a buoyancy apparatus 311 is secured to a chamber, in this case
a saturation diving bell 313. The buoyancy system 311 is similar to
that described in the fifth and sixth embodiments but also
incorporates a winch 315. This will allow the bell 313 to be
lowered away from the surface 15 if required.
[0164] As identified in the above embodiments, this invention
provides a third generation escape and rescue system. The third
generation of escape and rescue/abandonment technology consists of
a concept of `self help` that is capable of achieving a successful
outcome regardless of the depth of water in which the asset (e.g.
submarine, diving bell) is operating or located. In the event of a
malfunction or the asset is damaged (loss of power, fire, flood,
collision, mechanical failure or indeed any incident that could
disable the asset), the ability to surface immediately negates the
requirement to conduct risky buoyant ascent escapes from the ocean
floor or wait for an operational rescue vehicle to be deployed. It
could also prevent the asset from plunging to depths outside of its
capability (crush depth), avoiding complete loss of asset and all
personnel.
[0165] Referring to FIGS. 17 to 20, the invention according to an
eighth embodiment is shown. As this embodiment has components
similar to those mentioned in the previous embodiments, like
components will be similarly numbered as those discussed above. In
this embodiment the buoyancy system 11 is used to raise or lower
equipment, such as subsea manifolds 401 from or to the ocean floor.
FIG. 20 shows the buoyancy system 11 raising a subsea manifold 401
from the ocean floor 14 (FIG. 20b) to the surface 15 of the ocean
(FIG. 20a) for recovery by a ship.
[0166] As shown in FIGS. 17, 18 and 19 the buoyancy system 11 in
this embodiment is supported on a cradle 403. The buoyancy system
11 has an inflatable bag 17 located on an upper level of the cradle
403 and is stored in a collapsed condition as shown in FIG. 17.
Underneath the inflatable bag 17 is located the gas generation
system 35 comprising 14 vessels 37 which contain a medium 39, such
as an explosive, propellant or medium for generating gas (not
shown).
[0167] Each vessel 37 is coupled to a regulatory apparatus 43 and a
hydrostatic sensor 407 for regulating the amount of gas which
passes to the inflatable bag 17. Each vessel 37 is also coupled to
a heat exchanger 405 to assist in cooling the generated gas prior
to passing into the inflatable bag 17.
[0168] The activation system 21 is in the form of an acoustically
operated activation system 21d and a manually operated activation
system 21a which may be activated by an ROV. The activation system
21 is connected to a power supply 409.
[0169] Referring to FIG. 20, two stages of the recovery process of
the subsea manifold 401 is shown. The manifold 401 is secured to a
guide wire 411 which extends from the ocean floor to the surface
15. This assists in guiding the manifold 401 back to the surface 15
and provides a recovery unit with an accurate location to recover
the manifold 401 when it is raised.
[0170] In the first stage of the process, the cradle 403 of the
buoyancy system 11 is secured to the manifold 401 and is positively
buoyant so as to remain in an elevated position relative to the
manifold 401. This may be done by an ROV. At the same time a strop
413 is also connected. This is also positively buoyant so that it
remains above the manifold 401, allowing a crane from the recovery
unit to easily lift the manifold 401 from the ocean.
[0171] Once the buoyancy system 11 is secured to the manifold 401
and the manifold 401 has been disconnected from the surrounding
infrastructure, the activation system 21 may be activated to cause
gas to be generated and fed into the inflatable bag 17. Upon
activation, preferably through manual time delay or acoustic means,
a charge is sent from the power supply 409 to the hydrostatic
sensors 407 that are responsible for activating the gas generation
vessels 37. Water pressure, through hydrostatic sensors 407
determine the number of gas generation vessels 37 activated to
provide sufficient gas to inflate the inflatable body 17. Gas
produced by the gas generation vessels 37 pass through the heat
exchanger 405 and regulator 43 providing gas to a pneumatic
junction which then delivers the inflation gas to the inflatable
body 17 via a pneumatic hose(s) 415.
[0172] Further inflation will result in the buoyancy system 11
moving the manifold 401 in an upward direction. The manifold 401
will then move to a recovery position whereby it sits below the
surface 15 awaiting collection by the recovery unit.
[0173] As the manifold 401 rises, the pressure acting on the
inflatable bag 17 reduces. In order to prevent the pressure of the
gas inside the inflatable bag 17 from rupturing the inflatable bag
17, the excess gas is vented through the pressure relief valves 91
and/or 93 located at the top and bottom of the inflatable bag 17
respectively.
[0174] As the inflatable bag 17 is fully inflated, excess gas is
vented out of the inflatable bag 17 through pressure relief valves
91, 93. Upon reaching the surface, the gas pressure inside the
inflatable bag 17 reduces, the upper pressure relief valves re-seat
and may lock in the closed position to ensure that gas does not
escape from the inflatable bag 17, ensuring that the manifold 401
remains near the surface 15.
[0175] The required size and inflation of the inflatable body 17
depends on the weight of the submerged object. The number and size
of gas generation vessels required to be activated depends on both
the size of the inflatable body and the depth at which the
submerged object is resting.
[0176] Where the buoyancy system is attached to the manifolds 401
hard eye/lifting point, a positively buoyant lifting strop 413 is
also attached. The positively buoyant lifting strop 413 is to be
long enough so it's hard eye/lifting point is on the surface and
accessible once the manifold 401 arrives at the surface. This
allows a surface vessel to connect the positively buoyant lifting
strop 413 to a suitable crane to lift the manifold 401 and the
buoyancy system 11 out of the water and onto the deck of a ship,
barge, etc.
[0177] Once recovered, the buoyancy system 11 can be detached from
the manifold 401, the inflatable body 17 deflated and repacked,
activated/used gas generation vessels 37 replaced, upper relief
valves 91 unlocked/reset and power supply 409 re-charged. The
buoyancy system 11 then becomes ready for re-deployment.
[0178] A similar system as shown in FIG. 20 may also be used to
lower the manifold 401 to the ocean floor 14 in a controlled
descent. In such an application the buoyant force provided by the
buoyancy system 11 would need to be slightly less than the force
created by the weight of the manifold 401. However, as the manifold
401 descends further, it will be necessary to feed additional gas
into the inflatable bag 17 to overcome the additional pressure
acting on the inflatable bag 17 so as to maintain control of the
descent. In this regard the buoyancy system 11 may further comprise
a reservoir (not shown) for retaining a gas which may bleed into
the inflatable bag 17 as required.
[0179] Referring to FIGS. 17 to 20, the invention according to a
ninth embodiment is shown. This embodiment has particular
application in the exploration/mining industry. As this embodiment
has components similar to those mentioned in the previous
embodiments, like components will be similarly numbered as those
discussed above.
[0180] In this embodiment the buoyancy system 11 is particularly
adapted to lower equipment 912 to the ocean floor. FIG. 21 shows
the buoyancy system 11 connected to an object 12, during descent to
the ocean floor. The size of the object 12 will dictate the size of
the buoyancy system, and/or the number of inflatable bodies 16
which are to be inflated for the controlled descent.
[0181] The buoyancy system 11 has a securing point 903 to which is
attached a cable 909. The cable may be operated from a winch 914
located on a barge 916 at sea level (FIG. 23a), or by a crane on a
ship 915 (FIG. 23b).
[0182] In this embodiment the buoyancy system 11 comprises an
inflatable apparatus 19 comprising a hybrid system incorporating a
plurality of gas generation systems 35 and a gas storage system, in
a similar manner as that shown in FIG. 14.
[0183] The gas storage system comprises a pressure vessel 901.
Prior to descent the pressure vessel 901 is pressurised. In this
embodiment the pressurisation is through high pressure gas line
912, which is connected to pressure vessel 901 by quick release
high pressure gas line connection 904.
[0184] Once pressurised. gas from the pressure vessel 901 passes
through open regulators 905 to inflate inflatable bodies 16. Once
the buoyancy system 11 is fully immersed in water 15 and gas is
venting from the pressure relief valves 91 on all inflatable bodies
16 (signifying maximum upward buoyancy force) the buoyancy system
11 is ready for descent. The high pressure gas line 912 can then be
disconnected from the pressure vessel 901 and the buoyancy system
11 lowered to the sea floor by winch 914 (FIG. 23a) (or crane 913
(FIG. 23b)).
[0185] The buoyancy system 11 is lowered at a rate that allows all
inflatable bodies 16 to remain fully inflated. This can be
monitored by a load cell (not shown) within winch 914 (or crane
913), or by observing the gas venting from the pressure relief
valves 91 on the inflatable bodies 16.
[0186] Pressure inside the pressure vessel 901 is monitored by
internal pressure sensors 906, which are in communication with the
activation system 21. Once pressure within the pressure vessel 901
reduces to a pre-determined pressure, as sensed by pressure sensors
906, the activation system 21 sends an electronic charge to a gas
generation system 35a. The gas generation system 35a then produces
a gas which feeds into the pressure vessel 901, re-pressurising the
pressure vessel 901. This enables the pressure vessel 901 to
provide a continuous supply of gas to the inflatable bodies 16,
thus ensuring full inflation. Obviously this is critical as the
buoyancy system 11 descends deeper, exposing the inflatable bodies
16 to greater pressure.
[0187] If the pressure within the pressure vessel 901 reduces to
the pre-determined pressure for a second time, as sensed by the
pressure sensors 906, the activation system 21 will send an
electronic charge to a further gas generation system 35b to enable
the pressure vessel 901 to be re-pressurised. This process is
repeated until the buoyancy system 11 and the object 12 reach the
sea floor.
[0188] Once the object 12 is placed in the required position on the
sea floor, the inflatable bodies 16 can be deflated through dump
valves 917. The dump valves 917 may be activated by an ROV. Once
all Inflatable bodies 16 have been deflated, the securing points
907 securing the object 12 to the buoyancy system 11 are released.
The buoyancy system 11 is then winched back to the surface of the
water 15 by winch 914 (or crane 913).
[0189] In an alternative embodiment, the buoyancy system 11 may
cause one or more of the inflatable bodies 16 to re-inflate once
the object 12 is disconnected from the buoyancy system 11. In this
arrangement the inflated bodies 16 assist in returning the buoyancy
system 11 to the surface. This may be particularly relevant as
exploration and mining occur at increased depths. As depths
increase the cable 909 needs to be longer and is therefore
considerably heavier. It is therefore advantageous that the
buoyancy system 11 can also assist in returning the cable 909 to
the surface once the object has been positioned on the sea
floor.
[0190] The buoyancy system 11 shown in FIG. 21 is fitted with
sufficient gas generation systems 35 to ensure the buoyancy system
11 provides the required maximum upward buoyancy force until the
object 12 is positioned on the sea floor. The required maximum
upward buoyancy force will also determine the number and size of
Inflatable bodies 16.
[0191] Modifications and variations such as would be apparent to
the skilled addressee are considered to fall within the scope of
the present invention.
[0192] Throughout the specification, unless the context requires
otherwise, the word "comprise" or variations such as "comprises" or
"comprising", will be understood to imply the inclusion of a stated
integer or group of integers but not the exclusion of any other
integer or group of integers.
* * * * *