JP2014522923A - Apparatus and method for subsea storage - Google Patents

Abstract

An apparatus for subsea storage having a slurry inlet for receiving slurry from a subsea tool via a slurry transfer pipe, and a plurality of walls that together define a cavity having a storage volume with the sea floor. The wall is substantially made of a water permeable material such as a filter cloth or geotextile that allows for separation of water from the slurry while entraining and containing submarine material contained in the slurry received from the slurry inlet. To do. In a preferred form, the seabed storage device is a hood with an open bottom located on the bottom of the sea.

Description

  The present invention relates generally to underwater mining, and more particularly to an apparatus for subsea storage. In particular, the present invention is a submarine storage device that receives submarine material, typically ore slurry, from at least one submarine tool, from which the submarine material can be collected for transfer to a surface vessel. Although it relates to a submarine storage device that can be made, it is not limited to this.

BACKGROUND OF THE INVENTION Seabed drilling is often performed by dredging, for example, to recover valuable alluvial sand deposits or to maintain waterways navigable. For suction dredging, the end of the pipe or tube is positioned near the seabed material to be drilled, and a sea level pump is used to generate a negative differential pressure to remove seawater and nearby mobile seabed sediments. Sucking up with a pipe. The cutter suction trough further includes a cutter head at or near the suction inlet and dissociates even compressed soil, gravel, and hard rocks and sucks them into the tube. Large cutter suction rods can apply tens of thousands of kilowatts of cutting power. Other seabed dredging methods include auger suction, jet lift, air lift, and bucket dredging.

  Many dredging devices can usually only go to a depth of a few tens of meters, and even the larger dredging machine has a maximum dredging depth of only 100 meters. For this reason, corals are often limited to relatively shallow water.

Underwater boreholes, such as oil wells, may be conducted in waters several thousand meters deep. However, it is not possible to mine undersea using the borehole drilling technology.
Any discussion in this specification relating to documents, acts, materials, devices, articles or the like is merely to provide the context of the invention. Some or all of these matters may form part of the prior art standards, or may be common sense in the fields relevant to the present invention because they existed before the priority date of each claim of this application. It should not be interpreted as admission.

  Throughout this specification, the term “comprise” or variations such as “comprises” or “comprising” may refer to the indicated element, whole or step, or a plurality of elements. Should be understood to include any group of elements, complete bodies or steps, and exclude any group of elements, complete bodies or steps, or groups of elements, complete bodies or steps. Not what you want.

SUMMARY OF THE INVENTION According to a first aspect, the present invention provides a seabed storage device that is placed on the seabed in use, the device comprising:
A slurry inlet for attachment of a slurry transfer pipe and for receiving slurry from a subsea tool;
A plurality of walls generally defining a cavity having a storage volume, allowing water in the slurry to exit the device, while taking in and containing submarine material contained in the slurry in the device. And a wall configured to.

  Preferably, the seabed storage device is a hood. Preferably, the hood is open at the bottom. Preferably, the cavity is defined by the plurality of walls together with a sea bottom on which the seabed storage device is disposed. Preferably, the hood is repositionable, and at least a part of the plurality of walls is a plurality of movable parts that reduce a resistance load during movement of the submarine storage device. This movement may be the deployment of a seabed storage unit, relocation on the seabed, or recovery.

  Preferably, at least a part of the plurality of walls is water permeable. Preferably, at least a part of the plurality of walls includes a filtering material such as geotextile and / or a filtering structure such as an inclined plate settling tank or an inclined pipe settling tank, and the filtering structure contains a desired submarine material while containing water. Is allowed to go out. In a preferred form, the plurality of walls of the submarine storage device include both a filter media portion and a filtration structure portion, preferably a geotextile portion and an inclined plate settling tank or inclined tube settling tank portion, respectively.

  It is preferable that the filter medium is reversibly mounted so that the inward surface of the filter medium faces outward by reversing the mounting of the filter medium. The reversible mounting of the filter media has a number of advantages (for example, when fine submarine material is deposited on the filter media, the deposit tends to be washed away from the outer surface by further storage operations) Filter media can be selectively cleaned).

  The submarine storage device has a friction reduction mechanism that is used to reduce static friction (static friction) between the submarine storage device and the bottom of the sea where the submarine storage device is located when the device is lifted from the seabed. It is preferable to further provide. The friction reduction mechanism may include one or more fluid outlets proximate to the bottom of the device. Preferably, the fluid outlet is oriented substantially in the direction of the seabed. In use, the fluid outlet preferably fluidizes sediment and seabed material proximate to the seabed storage device.

  The friction reduction mechanism may alternatively or additionally include a plurality of movable walls. The plurality of movable walls are preferably accommodated inside the plurality of walls of the device, and surround the seabed material contained in the device. The plurality of movable walls preferably rotate relative to the plurality of walls of the device when the device is pulled up. The plurality of movable walls preferably swing away from the seabed material contained in the apparatus when rotating.

  The device preferably comprises at least one lifting tool for lifting and operating the device. The lifting tool is preferably connected to at least a moving system that allows the device to be lifted. It is also possible to provide an offset lifting device that is offset from the central axis of the device, preferably an offset lifting device that is located at or near the outer edge of the device. The offset lifting tool preferably lifts the device at an angle when the device is rearranged.

  Preferably, the submarine storage device is formed from at least two modules that are separately deployed from the surface vessel and configured to interconnect with each other in the water. The maximum deployment capability of a surface vessel deployment system may limit the size of the submarine storage device, and thus in some embodiments, the submarine storage device is configured to be separately surface deployed and underwater Formed of two or more modules configured to be submerged and interconnected at the sea floor. For example, such a modular submarine storage device, in some embodiments, can be up to 25 meters in diameter and up to 100T in water once formed from two or more modules.

  In embodiments of the present invention, the submarine storage device may include a storage retrieval device that can extract the material stored in the submarine storage device as a slurry. The storage and retrieval device may include an open port, such as a door of a submarine storage device, the open port being configured to collect the stored material, preferably as a slurry, when open. A suction inlet attached to the boom of the mine allows it to be introduced into the submarine storage device and restrains the stored material when closed. Additionally or alternatively, the storage take-out device of the submarine storage device can include a suction inlet and a slurry transfer pipe attached to and extending into the submarine storage device, The suction inlet of the submarine storage device is disposed at an appropriate position to flow and extract the stored material.

  Such an embodiment of the present invention recognizes that the desired slurry flow rate for entraining submarine material may differ significantly from the desired slurry flow rate, for example, to pull the slurry to a surface vessel by a riser and lift system. Therefore, these flow rates are divided using a seabed storage device. Thus, each flow rate can be optimized separately. For example, the slurry flow rate to the surface vessel is approximately 1,000 m3 / hour with an average ore concentration of about 12%, while the slurry flow rate into the submarine reservoir is about 3%, for example about 3%. 000 m3 / hour.

  In embodiments of the present invention, a submarine storage device minimizes the loss of particulates that settle slowly (referred to herein as “fines”) when positioned in a relatively flat portion of the seabed. Preferably, the submarine storage device is configured to form a hood that completely surrounds the storage volume in such a way as to suppress the storage volume. In such an embodiment, in order to accommodate a large amount of slurry inflow, the hood preferably allows submarine material to be filtered out of the slurry, allowing water to exit the mine volume. . For this purpose, preferably the effective surface area of the plurality of walls of the hood is formed from a filter medium that contains fines while allowing water to exit the hood. The grade of the filter media that is smaller in size than the solid particles can pass through the filter media allows the fine water containment while the required water flow out of the hood corresponds to the slurry inflow into the hood. It is preferably selected to maximize. For example, the filter medium may comprise a 50 micron grade silt curtain. The submarine hood preferably includes a three-dimensional frame that supports the filter medium in a state where a plurality of walls of the hood are formed of the filter medium.

  Incorporating fines from the slurry flowing into the hood is environmentally advantageous in avoiding the leakage of submarine material plumes, and more than 30% of the submarine materials that it is desirable to collect are such. It may be advantageous in terms of operation because it corresponds to a fine particle.

  The storage hood may have a plurality of slanted walls that form a generally frustoconical shape, the plurality of walls to avoid receiving a large outward pressure from the deposit of ore that is stored. The angle approximates the expected rill angle of the ore deposit.

  In addition, the present invention, in some embodiments, provides a submarine storage device that is adaptable to be deployed at significant depths. For example, some embodiments may be operable at depths greater than about 400 m, more preferably greater than 1000 m, and even more preferably greater than 1500 m. Nonetheless, it should be appreciated that some embodiments of the present invention may also provide a seabed mining option useful in shallow water, on the order of about 100 meters, or other relatively shallow underwater applications. Thus, the expression seabed or seabed is the invention for mining or excavating lake bottoms, estuary bottoms, fjord bottoms, inlet bottoms, bay bottoms, harbor bottoms, etc., whether in salt water, brackish water or fresh water. It should be recognized that such applications are not included in the scope of this specification.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a simplified overall view of an underwater system using a storage hood according to an embodiment of the present invention. FIG. 2a shows a storage hood according to an embodiment of the present invention. FIG. 2b shows a storage hood according to an embodiment of the present invention. FIG. 2c shows a storage hood according to an embodiment of the present invention. FIG. 2d shows a storage hood according to an embodiment of the present invention. FIG. 2e shows a storage hood according to an embodiment of the present invention. FIG. 2f shows a storage hood according to an embodiment of the present invention. Figure 3 shows the collection from the mine. FIG. 4 shows the piled storage. FIG. 5 shows a cross-sectional view of a storage hood with a plurality of inclined sedimentation tank panels. FIG. 6 shows a cross-sectional view of a storage hood with an offset lifting point. FIG. 7 shows a cross-sectional view of a storage hood provided with a friction reducing mechanism. FIG. 8a shows a cross-sectional view of another friction reduction mechanism in the rest position. FIG. 8b shows a cross-sectional view of the friction reduction mechanism shown in FIG. 8a in the raised position.

  FIG. 1 is a schematic overall view of an underwater system 100 according to an embodiment of the present invention. The derrick 102 and the dehydration plant 104 are mounted on a surface vessel as a production support vessel (PSV) 106 for ocean navigation. The PSV 106 has an ore transfer facility for loading the recovered ore on the cargo ship 108.

  While this embodiment provides a system 100 that can operate up to a depth of approximately 2500 m, alternative embodiments can be designed to operate at 3000 m or more. During production operations, one or more submarine mining tools (SMT) 112 are used to drill submarine material, preferably ore, from the seabed 110.

  The ore mined by the seabed mining tool 112 is collected as soon as it is cut, and is pumped from the seabed mining tool 112 to the seabed storage device 124 as a slurry through a storage transport pipe (STP) 128. The seabed storage device 124 allows separation of water from the slurry and takes ore from the slurry.

  The collection tool 114 collects the ore as a slurry from the inside of the submarine storage device 124 through the door 220 (see FIG. 2a) with a suction inlet attached to the boom into the submarine storage device 124. insert. Thereafter, the slurry is transferred to the base of the riser 122, where an underwater lift pump 118 is routed via a rigid riser 122 (shown abbreviated in FIG. 1 but can be up to 2500 m long in this embodiment). The slurry is pulled up to PSV106. The slurry is dehydrated by the plant 104 in the PSV 106. The wastewater is returned to the seabed under pressure to provide charge pressure for the subsea lift pump 118. The dewatered ore is unloaded onto a transport ship 108 that is transported to a storage facility before being transported to a treatment plant.

  2a to 2d show the storage device as the storage hood 124 in more detail. The storage hood 124 includes transfer pipe connectors 202 and 204, which are subsea hose connectors, and allow multiple ore tools 112 to collect ore into the hood storage 124 simultaneously. The slurry stream is guided into the hood substantially vertically downward by transfer pipe connectors 202 and 204. The hood 124 further includes a lifting device as a lift gear 206 for deployment, relocation and recovery of the hood 124.

The storage hood 124 has a plurality of walls including panels 208 that, together with the seabed 110, define cavities for storing seabed material (as shown in FIG. 3).
The panel 208 is removable and is formed from a frame 212 with a permeable skin as a geotextile cover 214.

  Due to the large geometry of the storage hood 124, the added mass in water associated with the device by the geotextile cover 214 is large. Due to this additional mass, the pulling resistance is dramatically increased in water compared to conventional lifts. Accordingly, in the present embodiment, the geotextile cover 214 can be rotated so as to be aligned in the moving direction before any lifting operation is performed. In order to reduce water resistance during movement of the storage hood 124, the panel 208 can be opened. The geotextile cover 214 reduces the outflow rate to allow larger residual soil particles to settle and retains fines larger than 30-60 microns. When the differential pressure of the filter medium rises due to the filtration hole being blocked, a relief valve or a flap is provided to avoid breakage of the filter medium.

  As shown in FIG. 2b, the storage hood 124 is formed from two modules 124a and 124b that can be deployed separately from a surface vessel and then brought together at the sea floor. This configuration allows the entire storage hood 124 to exceed the upper weight limit of the surface vessel deployment system. FIG. 2 c is a plan view of the storage hood 124, and FIG. 2 d is an elevation view of the storage hood 124.

  During the lifting and lowering operations, the resistance of the hood is very large. In order to reduce resistance, it is preferable to allow water to flow through the structure. 2e and 2f show the open flap 210 at the top of the storage hood 124 in the closed and open positions, respectively, in which the resistance during hood movement is reduced.

  The design of the storage hood 124 is prepared for access by the collector 300 through a door as the flap 220, which includes a collector as a suction inlet 302 attached to the boom of the collector 300. Included is a rubber panel with appropriately arranged slits that allow the mining portion to be inserted through the flap 220. The flaps 220 are provided at multiple locations for collecting from all sides of the mine and do not require power to function. The flap 220 is designed to avoid excessive slurry leakage when not in use by the collector 300.

  Thus, the present embodiment filters the ore slurry stream that is pumped from one or more subsea production tools. The slurry has a high flow rate and the slurry speed needs to be reduced so that the ore can settle to the seabed from the stream. The storage hood 124 is designed to reduce the amount of ore lost from the slurry stream and to minimize the ore pile disturbance that occurs when the storage hood 124 is repositioned. The storage hood 124 can be moved by an overhead crane on the ship so that it can be reused.

  The inflow of ore slurry is slowed in the storage hood 124 due to the large volume of the storage hood 124 and the large surface area covered by the geotextile cover 214. Larger ore particles in the slurry are fast set lines and settle into the reservoir in the slow flow area. A large volume of slurry stream passes through the geotextile cover 214 at a low speed, while the geotextile cover 214 filters out slowly settled particles from the slurry stream.

  FIG. 3 shows a mining machine 300 that collects ore from the storage 500 in the storage hood 124. In FIG. 3, the storage hood 124 is shown without a geotextile cover for clarity. With the geotextile cover installed, the collection portion 302 of the collection machine 300 is inserted through the flap 220 of the storage hood 124. FIG. 3 also shows the size of the maximum storage 502 that can be accommodated in the storage hood 124.

  FIGS. 4 a and 4 b show how a hood 124 with a rigid skirt 310 can be used to increase the size of a standard mine 500. The skirt 310 supports the ore in the mine 500 and allows the hood 124 to be overfilled, which is not possible with a non-bearing hood wall. The method includes overfilling the storage hood 124 with an overfilled storage 504 and lifting the storage hood 124 from the overfilled storage 504, ie, collapsing the overfilled storage 504. The collapsed storage 506, and then placing the storage hood 124 on the collapsed storage 506.

  FIG. 5 illustrates an embodiment of a storage hood 124 in which a portion of the geotextile cover 214 has been replaced with a filtration structure as an inclined settling tank 216. The inclined settling tank 216 can be either an inclined plate settling tank or an inclined pipe settling tank, but slides down the inclined surface of the inclined settling tank 216, returns to the storage hood 124, and solids reaching the storage 500 are collected. Allow upflow of water from the storage hood 124 while taking up. The inclined sedimentation tank 216 increases the sedimentation area per square meter of the outflow cross-sectional area which increases the sedimentation speed compared to the mere use of the geotextile cover 214 and maintains the same capacity output while the sedimentation hood 124 sinks. Allows an increase in capacity and / or a decrease in the size of the storage hood 124. As shown, instead of having a geotextile cover 214, it is also envisaged that the wall as a whole includes an inclined settling tank 216.

  FIG. 6 shows a storage hood 124 with an offset lifting tool as the offset lifting point 218. The offset lifting point 218 is positioned on the side of the storage hood 124 and allows the storage hood 124 to be lifted diagonally by the lifting tool 218 '. By using the offset lifting point 218 to raise the storage hood 124 at an angle, static friction that prevents the storage hood 124 from being lifted, that is, stiction (static friction) is reduced. In this regard, a small amount of surrounding deposit 501 can accumulate on the outer periphery of the storage hood 124, causing static friction between the hood 124 and the seabed 110 along with the storage 500.

  By lifting the storage hood 124 from the offset lifting point, the side of the storage hood 124 below the offset lifting point 218 is first pulled up, reducing the total release force required to overcome static friction. . Once the static friction is overcome, the central lift gear 206 can be used to lift and manipulate the deposit 124.

  FIG. 7 illustrates a friction reduction mechanism that also helps reduce static friction between the storage hood 124 and the seabed 110. Pipe transfer connectors 202 and 204 connected to the STP 128 have a diverter valve that diverts a portion of the flow down the duct 222 to a fluid outlet in the form of a nozzle 224 at the bottom of the storage hood 124. Is operable. When the diversion valve is activated, water pumped by the slurry pump system is pumped from the nozzle 224 into the duct 222. This water loosens the material on the outer periphery of the storage hood 124 including the surrounding deposits 501 and reduces friction between the storage hood 124 and the seabed 110. Once the static friction force is overcome, the storage hood 124 is operated relatively easily. It is also envisioned that air or other fluid is emitted from nozzle 224 instead of water.

  8a and 8b show further friction reduction mechanisms that can be used in place of or in addition to the previously described friction reduction mechanism shown in FIG. The friction reduction mechanism of FIGS. 8 a and 8 b has a plurality of movable walls 230 inside the storage hood 124. The movable wall 230 is rotatable with respect to the side of the storage hood 124. As shown in FIG. 8 a, the storage 500 is held inside the movable wall 230 of the storage hood 124. When the storage hood 124 is pulled up, it rotates downward and away from the storage 500 as shown in FIG. By this operation, the static frictional force between the storage hood 124 and the sea floor 110 is effectively eliminated.

  Those skilled in the art will appreciate that many variations and / or modifications to the present invention may be made without departing from the spirit or scope of the invention as broadly described, as shown in certain embodiments. I will. Therefore, this embodiment should be regarded as illustrative in all respects and not as restrictive.

Claims (26)

A seabed storage device that is placed on the seabed during use,
A slurry inlet for attachment of a slurry transfer pipe and for receiving slurry from a subsea tool;
A plurality of walls generally defining a cavity having a storage volume, wherein water in the slurry is allowed to exit the device, while taking in submarine material contained in the slurry in the device; A device comprising a wall configured to receive.   The seabed storage apparatus according to claim 1, wherein the seabed storage apparatus is a hood having an open bottom.   The submarine storage device according to claim 2, wherein the plurality of walls define the cavity together with a bottom surface on which the submarine storage device is disposed.   The seabed storage device according to any one of claims 1 to 3, wherein the plurality of walls are water permeable.   The submarine storage device according to any one of claims 1 to 4, wherein at least some of the plurality of walls are made of a filter medium.   The seabed storage device according to claim 5, wherein the filter medium is reversibly mounted so that the inward surface of the filter medium faces outward by reversing the mounting of the filter medium.   The seabed storage device according to claim 5 or 6, wherein the filter medium is a geotextile.   The seabed storage device according to any one of claims 1 to 7, wherein at least some of the plurality of walls include a filtration structure.   The seabed storage device according to claim 8, wherein the filtration structure is an inclined plate settling tank or an inclined pipe settling tank.   10. The apparatus according to claim 1, further comprising a plurality of movable parts movable between a storage position and a movement position, wherein a resistance load during movement of the seabed storage device is reduced at the movement position. The seabed storage device according to the item.   The seabed storage device according to any one of claims 1 to 10, further comprising at least one friction reduction mechanism that reduces static friction between the seabed storage device and the seabed.   The seabed storage device of claim 11, wherein the friction reduction mechanism includes one or more fluid outlets proximate to a bottom of the seabed storage device.   The seabed storage device of claim 12, wherein the one or more fluid outlets are fluidly connected to a diverter valve at the slurry inlet via a duct.   14. A seabed storage device according to claim 12 or 13, wherein the one or more fluid outlets are oriented substantially in the direction of the seabed.   The submarine storage device according to any one of claims 12 to 14, wherein the one or more fluid outlets include a plurality of nozzles.   The seabed storage device according to claim 11, wherein the friction reduction mechanism includes a plurality of movable walls.   The submarine storage device according to claim 16, wherein the plurality of movable walls are preferably accommodated inside the plurality of walls of the submarine storage device, and surround a submarine material contained in the device. .   The seabed storage device according to claim 16 or 17, wherein the plurality of movable walls rotate with respect to the plurality of walls of the seabed storage device.   The seabed storage device according to any one of claims 1 to 18, further comprising a lifting tool.   The seabed storage device according to any one of claims 1 to 19, further comprising an offset lifting tool deviated from a central axis of the seabed storage device.   21. The seabed storage apparatus according to claim 20, wherein the offset lifting tool is disposed in proximity to an outer edge of the seabed storage apparatus.   The seabed storage device according to any one of the preceding claims, wherein the seabed storage device is formed from at least two modules that are separately deployed from a surface vessel and configured to interconnect with each other in water. Mining equipment.   The seabed storage device according to any one of claims 1 to 22, further comprising a storage storage takeout device.   24. The seabed storage device according to claim 23, wherein the storage and retrieval device has an open port in at least one of the plurality of walls of the seabed storage device.   The seabed storage device according to any one of claims 1 to 24, wherein the plurality of walls are placed obliquely to form a substantially truncated cone shape.   The seabed storage apparatus according to any one of claims 1 to 25, further comprising a rigid skirt portion on an outer periphery of the seabed storage apparatus.

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