Underwater isobaric suspension type oil and liquid storage device and operation method thereof

Abstract

An underwater isobaric suspension type oil and liquid storage device and its operation method, the device comprises an underwater operation main body, a buoyancy cabin, a ballast cabin, a counterweight cabin, a mooring system, an attitude monitoring module, an underwater control module and an underwater docking interface, a water storage cabin and an oil storage cabin are arranged in the underwater operation main body as a matched liquid storage module. The underwater control module controls the ballast system to discharge seawater according to the attitude, depth, mooring load and liquid storage state information, so that the device maintains the preset net buoyancy and attitude under the change of liquid storage quantity and the disturbance of sea current; the buoyancy cabin and the counterweight cabin form a stable configuration of the center of buoyancy and the center of gravity, the mooring system is connected with the gravity anchor through a quick release device, and can be remotely released under abnormal load or fault condition; the underwater docking interface is used for detecting, maintaining and fluid pipeline docking of an underwater robot or an operation tool. The present application has the attitude regulation and control, remote monitoring, emergency release and underwater operation and maintenance capabilities of deep sea suspension operation, and is suitable for safe storage and transportation of deep sea oil and liquid or other liquid.

Description

Technical Field

[0001] This invention relates to marine engineering and underwater operation equipment technology, and in particular to an underwater isobaric suspended oil and liquid storage device and its operation method, which has the functions of isobaric liquid storage, buoyancy adjustment, attitude monitoring, remote control, emergency release and underwater docking and maintenance. Background Technology

[0002] Deep-sea underwater equipment operates in environments characterized by high hydrostatic pressure, low temperature, ocean current disturbance, and limited accessibility. For suspended equipment, the device must not only perform liquid storage functions but also maintain controllable suspension depth and spatial attitude under load changes, liquid mass changes, and ocean current effects, while possessing reliable underwater monitoring, fault handling, and in-situ operation and maintenance capabilities.

[0003] Existing surface storage and unloading facilities are susceptible to typhoons and large waves, and mooring systems and export pipelines are subjected to significant alternating loads. Gravity-supported submersible tanks rely on seabed foundation treatment, resulting in high deployment and relocation costs. Therefore, integrating the liquid storage module into an adjustable-load submersible floating operation body is beneficial for reducing the impact on the marine environment and improving equipment reusability.

[0004] However, existing underwater suspended liquid storage solutions typically revolve around the pressure-bearing tank or liquid-containing structure, lacking system design for underwater operations: changes in liquid mass can easily cause net buoyancy and attitude drift; there is a lack of linkage between load adjustment, unloading, and remote emergency release when mooring loads are abnormal; status monitoring information is scattered, making it difficult to form underwater closed-loop control; and there is a lack of standardized interfaces between the device and underwater robots or tools, resulting in inspection, maintenance, and pipeline connections relying on complex recovery operations.

[0005] Furthermore, the low temperatures in the deep sea may reduce the fluidity of highly viscous crude oil, and direct exchange of storage fluid with seawater also poses a pollution risk. Therefore, there is a need for underwater operational equipment that focuses on deep-sea suspension stability, safe underwater operations, and underwater mooring maintenance, while also taking into account isobaric storage, physical isolation, and temperature protection.

[0006] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] The main objective of this invention is to overcome the deficiencies in the aforementioned background technology and provide an underwater isobaric suspension oil and liquid storage device and its operation method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: An underwater isobaric suspension oil and liquid storage device, comprising: The main underwater operation unit is suspended above the seabed and is equipped with a buoyancy chamber, a load adjustment chamber, a counterweight chamber, a mooring system, an attitude monitoring module, an underwater control module, and an underwater docking interface. The buoyancy chamber is located on the upper part of the underwater working body and is used to provide structural buoyancy; the counterweight chamber is located on the lower part of the underwater working body and is used to lower the center of gravity. The buoyancy chamber and the counterweight chamber work together to form an attitude-stable configuration with the center of buoyancy higher than the center of gravity. The loading chamber is equipped with a loading system, which includes a seawater pump, a control valve, and an inlet / outlet pipe. The system is used to pump seawater in or out according to the control command of the underwater control module in order to adjust the mass, net buoyancy, and attitude of the underwater working body. The attitude monitoring module is used to collect information on the attitude, depth, mooring load, and liquid storage status of the underwater working body; the underwater control module is communicatively connected to the attitude monitoring module and the load adjustment system, and is used to control the load adjustment system in a closed loop based on the information. The mooring system includes a quick release device, a mooring cable, and a seabed anchor installed on the underwater working body. The quick release device can disconnect the underwater working body from the mooring cable according to a remote release command or an abnormal load trigger command. The underwater docking interface is used to detachably dock with underwater robots, remotely operated vehicles, or underwater work tools to perform status detection, control communication, fluid pipeline connection, or component maintenance. The underwater operation body is also equipped with a water storage tank and an oil storage tank as supporting liquid storage modules. The water storage tank is connected to the external seawater at the same pressure, and the oil storage tank includes a flexible reservoir and is connected to the external liquid delivery system through inlet / outlet pipes.

[0009] An operating method for an underwater isobaric suspended oil and liquid storage device as described above includes: collecting attitude, depth, and mooring load information after deployment; controlling the loading system to allow seawater to enter and exit based on the collected information, so that the device maintains a preset suspension depth, net buoyancy, and attitude; synchronously adjusting the loading water volume according to the mass change of the stored liquid when it enters or exits; and docking with an underwater robot or underwater work tool through an underwater docking interface to perform detection, maintenance, or fluid transfer.

[0010] The present invention has the following beneficial effects: This invention proposes an underwater isobaric suspended oil and liquid storage device and its operation method. The isobaric storage module is configured in a deep-sea suspended operation body with active load adjustment, attitude monitoring, remote control, underwater docking, and emergency release capabilities. This allows the device to form a complete underwater operation link around deployment, operation, maintenance, and emergency response. Compared with traditional gravity-based bottom-mounted oil storage structures, which rely on harsh seabed foundation conditions, require expensive in-situ seabed construction, and cannot be relocated and reused, this invention adopts an underwater suspended design, allowing the underwater operation body to float at a certain height above the seabed. This completely eliminates the limitations of water depth and seabed geology on device deployment, eliminates the need for expensive and time-consuming seabed foundation treatment, greatly shortens the project cycle, reduces construction costs, and endows the device with excellent mobility and reusability, which can flexibly meet the needs of deep-sea offshore oilfield development and equipment relocation.

[0011] To address the technical challenge of existing underwater suspension solutions where the density difference between the storage liquid and ballast water causes drastic fluctuations in net buoyancy during the replacement process, leading to long-term exposure of the mooring system to severe alternating loads, this invention incorporates a load adjustment chamber and its built-in load adjustment system within the main operating unit. During the dynamic process of water replacement involving the storage liquid entering and exiting the associated storage module, this load adjustment system can synchronously pump in or discharge seawater in real time according to instructions from the underwater control module to precisely compensate for changes in the device's mass. This ensures that the overall total mass and net buoyancy of the underwater operating unit remain absolutely constant under any storage liquid operating condition. This significantly reduces the stress extremes and fatigue design difficulty of the mooring system under different operating conditions, effectively extends the mooring fatigue life, and reduces construction and maintenance costs. Meanwhile, the invention places the buoyancy chamber on the upper part of the main body to raise the center of buoyancy, and the counterweight chamber on the lower part of the main body to lower the center of gravity. The buoyancy chamber and center of gravity are stably configured to achieve a dual mechanical stability effect, giving the device extremely high attitude stability under complex deep-sea current disturbances. The quick release device on the main body is connected to the mooring cable, and the underwater control module monitors the mooring tension in real time. Under abnormal load or fault conditions, it can be remotely triggered to release, ensuring that the device can quickly detach from the mooring system in the event of extremely bad sea conditions or sudden emergencies, which greatly improves the safety redundancy of offshore operations.

[0012] The attitude monitoring module comprehensively collects information on the main body's attitude, depth, mooring load, and liquid storage status. The underwater control module fuses and cross-checks data from multiple sensors, implementing degraded control when some sensors malfunction, ensuring that the device's net buoyancy, suspension depth, height above the bottom, attitude deviation, and mooring load remain within preset ranges. This significantly improves the system's fault tolerance and long-term autonomous operation reliability in complex deep-sea environments. The underwater docking interface allows underwater robots or tools to perform tasks such as inspection, maintenance, control takeover, and fluid transfer in-situ, effectively reducing reliance on overall recovery and diver operations, significantly lowering maintenance costs, and expanding the device's operational applicability.

[0013] In summary, this invention, through the systematic integration of underwater levitation, closed-loop load adjustment, buoyancy-center-of-gravity stabilization, mooring tension monitoring and emergency release, underwater docking and maintenance, and supporting liquid storage functions, enables the device to form a complete underwater operation chain around deployment, operation, maintenance, and emergency response. Based on the actual development needs of deep-sea engineering and specific sea conditions, with its outstanding advantages such as high economy, high reliability, high mobility, and no pollution, it can seamlessly integrate into and optimize the existing marine oil and gas development technology system, providing a reliable technical path for large-scale, low-cost commercial development of deep-sea oil and gas resources to reduce costs and increase efficiency.

[0014] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall installation, mooring, and external sensor arrangement of the underwater isobaric suspended oil and liquid storage device according to an embodiment of the present invention.

[0016] Figure 2 This is a cross-sectional view of the underwater isobaric suspended oil and liquid storage device and a schematic diagram of the internal sensor arrangement according to an embodiment of the present invention.

[0017] Figure 3 This is a schematic diagram of multi-source sensor fusion, redundant control, and actuator connection in an embodiment of the present invention.

[0018] Figure 4 The following is a partial structural diagram of key parts in an embodiment of the present invention, wherein: (a) is a series installation structure of the quick release device and the mooring tension sensor; (b) is a structure of the underwater docking interface and docking sensing component; (c) is a partial arrangement diagram of the flexible reservoir, support, movable heat insulation partition, baffle and related sensors in the liquid storage state; and (d) is a modular installation structure of the inlet / outlet pipe and water circuit sensor. Detailed Implementation

[0019] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0020] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for fixing, coupling, or communication.

[0021] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] This embodiment focuses on deep-sea levitation operations, with oil and liquid storage functions serving as supporting liquid storage capabilities for the main underwater operations. The device achieves passive attitude stabilization through a buoyancy-center-of-gravity stable configuration, active attitude adjustment through the attitude monitoring module 20, underwater control module 21, and load adjustment system 7, and ensures mooring safety and in-situ maintenance through the quick release device 14, underwater docking interface 22, and seabed anchor 23.

[0024] See Figure 1 and Figure 2 The underwater operation body 1 is suspended above the seabed. Its upper part is equipped with a buoyancy chamber 2, a load adjustment chamber 3, and an attitude monitoring module 20, while its lower part is equipped with a counterweight chamber 6. The load adjustment chamber 3 houses a load adjustment system 7. The underwater operation body 1 is moored and restrained by a quick release device 14, mooring cables 15, and a seabed anchor 23. An underwater control module 21 and an underwater docking interface 22 are located on its side. Inside the body, a water storage tank 4 and an oil storage tank 5 constitute a matching liquid storage module. The oil storage tank 5 consists of a flexible reservoir 11 and a support frame 12.

[0025] like Figures 1 to 4As shown, the attitude monitoring module 20 is a system collective term including distributed sensing nodes, field acquisition nodes, and signal links, not a single top sensor; the box indicated by label 20 in the figure is its field aggregation unit. The inertial measurement unit 24 is installed on a rigid load-bearing base near the central axis at the top of the underwater operating body 1. At least two sets are provided, a primary and a backup. The primary and backup inertial measurement units 24 are spaced apart, with their sensitive axes aligned with the main body's coordinate axes, and maintained at a distance from vibration sources such as pumps and valves. They are used to measure triaxial acceleration, triaxial angular velocity, and device attitude. Depth or water pressure sensors 25 have at least two circumferentially spaced redundant measuring points at the isobaric measuring ports at the upper and lower middle parts of the main body. The pressure ports are connected to external seawater. The installation depth and the main body's tilt state are checked by the consistency of redundant measuring points at the same height and the hydrostatic pressure difference between measuring points at different heights.

[0026] See Figure 1 , Figure 2 and Figure 4 (a) Each mooring branch is equipped with a mooring tension sensor 26. The mooring tension sensor 26 is preferably installed at the bearing connection pin or series tension member between the quick release device 14 and the mooring cable 15, so that the tension of each branch can be measured independently. The locking position of the quick release device 14 can also be equipped with a dual-channel travel or proximity switch to confirm the locked, unreleased and released states.

[0027] A distributed fiber optic strain sensor array 27 is installed on the outer shell of the underwater working body 1. The distributed fiber optic strain sensor array 27 forms multiple longitudinal measuring lines along the main body's axis, and forms circumferential measuring rings in the connection areas between the buoyancy chamber 2, the load adjustment chamber 3, the oil storage tank 5, and the fixed bulkheads 8, 9, 10 and the shell; denser measuring points are set at the mounting base of the quick release device 14 and the pipeline penetration areas. The temperature channel in the array is used only for strain temperature compensation to avoid functional confusion with the liquid storage temperature sensor 30. This enables the identification of local stress concentration, overall bending, elliptic deformation, and fatigue accumulation.

[0028] See Figure 2 and Figure 4 (d) A multi-parameter sensor 28 for the storage pipeline is installed on the inlet / outlet pipe 19, preferably located upstream and downstream of the underwater docking interface 22 or the main control valve, to measure bidirectional flow, pressure, temperature, and differential pressure. Water flow, pressure, and load-balanced water volume sensor groups 29 are respectively installed on the load-balanced tank inlet / outlet pipe 16 and the water storage tank inlet / outlet pipe 17. Pressure measuring points are installed at the seawater pump inlet, outlet, and both sides of key valves, and liquid level or differential pressure measuring points are installed in each load-balanced unit. The underwater control module 21 calculates the actual load-balanced water volume by cross-referencing the pipeline cumulative flow, load-balanced unit liquid level or differential pressure, and pump operating parameters, and performs a mass conservation check in conjunction with the storage flow to identify integral drift, blockage, valve jamming, pump efficiency degradation, or unplanned leakage.

[0029] Multiple temperature sensors 30 are installed on the outer surface of the flexible storage tank 11 along its upper, middle, and lower parts. Temperature measuring points are also added near the active heating area of ​​the fixed partition 10, the insulation partition 13, and the inlet / outlet pipe 19 to reconstruct the axial and radial temperature distribution of the stored liquid. Leakage sensors 31 are installed in the upper oil accumulation area of ​​the water tank 4, the isolation boundary between the oil tank 5 and the water tank 4, the pipe penetration sealing point, and before the discharge outlet of the water tank inlet / outlet pipe 17. The leakage sensors 31 may include at least two of the following: hydrocarbon detectors, oil film detectors, and oil content detectors in water, to perform dual-point confirmation through different measurement principles, and to close the discharge valve first when the oil content exceeds the threshold.

[0030] See Figure 2 and Figure 4 (c) The flexible reservoir deformation and insulation partition displacement sensor group 32 includes: flexible strain gauges or fiber optic gratings arranged along at least two meridional lines and at least two circumferential sections of the flexible reservoir 11, and a linear displacement sensor or encoder arranged along the guide path of the insulation partition 13. The sensor group 32 is used to detect the degree of expansion of the flexible reservoir 11, local wrinkles, asymmetric deformation, and the actual position of the insulation partition 13. The underwater control module 21 cross-validates the three liquid volume estimates formed by the inlet / outlet flow rate integration, flexible reservoir deformation, and insulation partition displacement to determine integral drift, partition jamming, or abnormal reservoir folding.

[0031] See Figure 1 , Figure 2 and Figure 4 (b) A docking sensing component 33 is installed around the underwater docking interface 22. The docking sensing component 33 includes at least three of the following: a close-range imaging sonar, a low-light camera, a visual marker recognition unit, a relative pose sensor, a locking position sensor, and an interface sealing cavity pressure sensor. It is used to guide the underwater robot 36 to complete the approach, alignment, insertion, locking, and sealing confirmation. A three-dimensional ocean current sensor 34 is arranged on the upper part of the underwater working body 1 via an extended bracket, avoiding the hull, mooring cable 15, and the wake of the inlet and outlet. It is used to measure the ocean current velocity and direction. The acoustic positioning communication and bottom-distance measurement component 35 includes an acoustic transponder 35a arranged on the top or upper outer edge of the main body in an unobstructed area, and an acoustic bottom-distance altimeter 35b arranged on the bottom of the counterweight tank 6 facing the seabed. It is used to simultaneously obtain the underwater position, low-speed emergency communication information, and the safe bottom-distance height of the device relative to the seabed.

[0032] After the underwater robot 36 connects to the underwater docking interface 22, it can read raw sensor data, perform calibration checks, or replace modular sensors. The remote monitoring terminal 37 receives status data via a communication link within the mooring cable, an underwater acoustic link, or a fiber optic link. The edge data acquisition and synchronization module 38 is located near the underwater control module 21, implementing unified timestamps, channel self-checks, data buffering, and link interruption resumption for each sensor, and employs mutually isolated main and backup power supply branches.

[0033] In a preferred embodiment, the underwater control module 21 is equipped with a main controller 21a and a backup controller 21b that monitor each other. The two controllers form a multi-source state estimate based on inertial measurement, hydrostatic pressure, acoustic positioning, ocean current, mooring tension, and fluid mass balance results; fault isolation is achieved through sensor residuals, rate of change constraints, and physical model consistency. When a single measuring point drifts or fails, the abnormal channel is blocked and the corresponding state is reconstructed by other measuring points; when communication is interrupted or there are insufficient effective measuring points, the device enters a degraded safety mode that limits the load adjustment rate, maintains positive stability, and prohibits unnecessary release actions.

[0034] In some embodiments, the remote monitoring terminal 37 runs an online-updable digital twin model of physical information. The model is constrained by buoyancy-gravity balance, six-degree-of-freedom hydrodynamics, mooring cable nonlinear mechanics, load adjustment pump valve characteristics, flexible reservoir 11 deformation, and heat transfer model. Based on field sensor data, it identifies the ocean current drag coefficient, mooring stiffness, pump efficiency, reservoir equivalent stiffness, and heat transfer parameters online, and outputs attitude, mooring fatigue, shell strain, reservoir remaining life, and pipeline blockage risk predictions with confidence intervals. The prediction results, together with the measured residuals, are used for sensor drift diagnosis, maintenance sequencing, and control parameter updates.

[0035] The sensor mounting bases, penetration components, and electrical connectors all employ pressure- and corrosion-resistant constructions adapted to the target water depth. Sensors in direct contact with seawater are equipped with replaceable biofouling shields or cleaning mechanisms. The installation orientation, zero point, range, and calibration coefficients of each sensor are written into the edge data acquisition and synchronization module 38 before deployment and are verified during on-site maintenance by the underwater robot 36, thereby improving maintainability and data traceability under long-term service conditions.

[0036] The underwater control module 21 calculates the target load adjustment value based on attitude angle, angular velocity, depth, mooring tension, and changes in the mass of the stored liquid, and controls the seawater pump and control valve to pump or discharge seawater into or out of the load adjustment tank 3. The control process can employ threshold control, proportional-integral-derivative control, or model predictive control to maintain the net buoyancy, suspension depth, and tilt angle of the device within a preset range.

[0037] The underwater docking interface 22 is equipped with a mechanical guide and a locking part, and can be configured with a wet-plug communication connection, a hydraulic or electrical connection, and a fluid connection. After the underwater robot or remotely operated vehicle completes docking under the guidance of the guide, it can read status data, upload control parameters, take over local control, connect inlet / outlet fluid pipes 19, or replace maintainable parts.

[0038] The buoyancy chamber 2 can adopt a sealed air pressure balance type or an open material filling type structure to reduce the pressure difference of the shell caused by the hydrostatic pressure in the deep sea. The buoyancy chamber 2 is set in the upper part and the counterweight chamber 6 is set in the lower part, so that the center of buoyancy is higher than the center of gravity, and it still has the passive stabilization ability to restore the upright attitude when the control system loses power.

[0039] The ballast tank 3 is connected to the external seawater via inlet / outlet pipe 16, and the water storage tank 4 is connected to the external seawater via inlet / outlet pipe 17. The ballast system 7 performs mass compensation according to changes in the mass of the stored liquid, and can be equipped with two or more independent ballast units on the left and right or in the circumferential direction, generating attitude adjustment torque through differential inlet and outlet.

[0040] The mooring system includes a quick release device 14, a mooring cable 15, and a seabed anchor 23. When the mooring tension exceeds a first threshold, the underwater control module 21 controls the ballast system 7 to reduce unfavorable net buoyancy or correct the tilt angle; when the tension exceeds a second threshold, a mooring malfunction is detected, or a remote emergency command is received, the quick release device 14 activates. After release, the device enters a preset safe buoyancy state through the ballast system 7 and transmits position and status information.

[0041] The oil storage tank 5 serves as a supporting liquid storage module, connected to an external liquid delivery system or an underwater docking interface 22 via inlet / outlet pipes 19; the flexible reservoir 11 isolates the stored liquid from the seawater in the water storage tank 4. The thermal insulation partition 13 moves with changes in the volume of the stored liquid, and the baffle 18 restricts its downward position to reduce the possibility of the flexible reservoir 11 folding or forming dead folds.

[0042] The fixed partition 10 can be equipped with an active heating layer and a phase change energy storage layer. The underwater control module 21 controls the heating power based on temperature sensor information. The phase change energy storage layer absorbs heat during heating and releases heat during low-temperature shocks or when heating is paused. This temperature control function is suitable for low-temperature sensitive liquids such as high-pour-point crude oil and does not constitute a limitation on the type of liquid stored.

[0043] This invention also provides an operating method for an underwater isobaric suspension oil and liquid storage device, comprising the following steps: Deployment and initial leveling: After the device is lowered to the target water depth, the underwater control module 21 reads the attitude, depth and mooring tension information, and controls the load adjustment system 7 to allow seawater to enter and exit, so that the device reaches the preset suspension depth, net buoyancy and tilt angle; the buoyancy tank 2 and the counterweight tank 6 maintain passive stability.

[0044] Storage and drainage: The stored liquid enters or exits the flexible storage tank 11 through the inlet / outlet pipe 19, and the water storage tank 4 correspondingly discharges or draws in seawater; the underwater control module 21 synchronously controls the load adjustment system 7 according to the flow rate or mass change to compensate for the density difference and mass change between the stored liquid and the seawater.

[0045] Normal levitation operation: Attitude monitoring module 20 continuously collects information on inertia, water pressure, acoustic positioning, ocean current, mooring tension, shell strain and liquid storage status; edge data acquisition and synchronization module 38 completes time synchronization and channel health check; underwater control module 21 adjusts the load water volume according to the fusion state, and controls multiple load adjustment units to differentially inflate and depress water when necessary to restore the preset levitation depth and attitude.

[0046] Underwater docking and maintenance: The underwater robot or remotely operated vehicle connects to the underwater docking interface 22 to perform visual inspection, sensor calibration, data reading, control parameter updates, fluid pipeline connection, or replacement of maintainable components; after the operation is completed, the locking is released and the vehicle is withdrawn.

[0047] Abnormal Handling: When the mooring tension or attitude deviation exceeds the warning threshold, load adjustment, unloading, and attitude restoration are performed first; if the abnormality persists, the load exceeds the release threshold, or a remote emergency command is received, the quick release device 14 is triggered. After release, the device enters a safe levitation state and sends positioning and fault information for subsequent recovery or re-mooring.

[0048] The following further describes the implementation, working principle, and advantages of specific embodiments of the present invention.

[0049] An underwater isobaric suspended oil and liquid storage device mainly includes an underwater operating body 1 suspended above the seabed. The underwater operating body 1 integrates a buoyancy chamber 2, a load adjustment chamber 3, a counterweight chamber 6, a mooring system, an attitude monitoring module 20, an underwater control module 21, and an underwater docking interface 22. The buoyancy chamber 2 is located on the upper part of the underwater operating body 1 to provide structural buoyancy, while the counterweight chamber 6 is located on the lower part of the underwater operating body 1 to lower the center of gravity. Together, they form a stable attitude configuration with the center of buoyancy higher than the center of gravity. The load adjustment chamber 3 contains a load adjustment system 7, which includes a seawater pump, control valves, and inlet / outlet pipes 16. It is used to pump seawater in or out according to the instructions of the underwater control module 21 to adjust the mass, net buoyancy, and attitude of the underwater operating body 1. The attitude monitoring module 20 collects information on the attitude, depth, mooring load, and liquid storage status of the underwater operating body 1. The underwater control module 21 is communicatively connected to the attitude monitoring module 20 and the load adjustment system 7, and uses the information to perform closed-loop control of the load adjustment system 7. The mooring system includes a quick release device 14, a mooring cable 15, and a seabed anchor 23 installed on the underwater operation body 1. The quick release device 14 can disconnect the underwater operation body 1 from the mooring cable 15 according to a remote release command or an abnormal load trigger command. The underwater docking interface 22 is used to detachably dock with an underwater robot 36, a remotely operated vehicle, or an underwater operation tool to perform status detection, control communication, fluid pipeline connection, or component maintenance. The underwater operation body 1 is also equipped with a water storage tank 4 and an oil storage tank 5 as supporting liquid storage modules. The water storage tank 4 is connected to the external seawater at equal pressure through an inlet / outlet pipe 17, and the oil storage tank 5 includes a flexible reservoir 11 and is connected to an external liquid delivery system through an inlet / outlet pipe 19.

[0050] The underwater working body 1 is suspended at a certain height on the seabed. Its internal cavity, from top to bottom, is configured as follows: buoyancy chamber 2, load adjustment chamber 3, water storage chamber 4, oil storage chamber 5, and ballast chamber 6. The positions of the buoyancy chamber 2, load adjustment chamber 3, water storage chamber 4, oil storage chamber 5, and ballast chamber 6 can be adjusted according to specific needs. Load adjustment system 7 is installed in load adjustment chamber 3. Buoyancy chamber 2 and load adjustment chamber 3 are separated by a fixed bulkhead 8, load adjustment chamber 3 and water storage chamber 4 are separated by a fixed bulkhead 9, and oil storage chamber 5 and ballast chamber 6 are separated by a fixed bulkhead 10. Oil storage chamber 5 is composed of a flexible reservoir 11 and a support frame 12. Insulated bulkhead 13 separates water storage chamber 4 and oil storage chamber 5, and moves with the rise and fall of the water level.

[0051] The attitude monitoring module 20, underwater control module 21, and edge data acquisition and synchronization module 38 employ redundant power supply, a unified clock, and dual-channel communication. The remote monitoring terminal 37 displays the device's attitude, depth, ocean current, tension of each mooring branch, hull strain, ballast tank water volume, liquid volume, pipeline differential pressure, liquid temperature, reservoir deformation, leakage, and docking status. It also allows authorized operators to issue ballast, sensor calibration, docking preparation, and emergency release commands. In the event of a remote link interruption, local safety control continues to operate without relying on the remote terminal.

[0052] Under normal operating conditions, the top buoyancy tank 2 and the bottom counterweight tank 6 provide static restoring torque, and the load adjustment system 7 only compensates for slowly changing liquid mass and mean current load, thereby reducing the frequency of pump and valve operation and energy consumption. Under disturbed operating conditions, the controller increases the sampling and adjustment frequency to prioritize ensuring that the inclination angle and mooring tension do not exceed the allowable values.

[0053] The underwater docking interface 22 can be positioned on the side of the main body, facilitating the underwater robot's access while avoiding the mooring cable 15. Acoustic beacons, visual markers, or mechanical funnel guides can be installed around the interface to improve the docking success rate in murky water and low-light conditions.

[0054] The load adjustment system 7 may specifically include a seawater pump, inlet and outlet control valves, load adjustment pipelines, liquid level or pressure sensors, flow sensors and controllers; multiple load adjustment units may be distributed circumferentially to generate attitude adjustment torque through differential water volume.

[0055] The flexible reservoir 11 and the water storage tank 4 form a physically isolated water-liquid replacement structure. During operation, the pressure on the liquid storage side is kept slightly higher than the pressure on the seawater side, and the extreme position of the thermal insulation partition 13 is limited by the baffle 18 to maintain the smooth stress shape of the flexible reservoir 11.

[0056] The quick release device 14 can employ a hydraulic, electric, explosion bolt, or mechanical energy storage actuator, and is equipped with anti-false triggering logic. Remote release commands should preferably employ double confirmation; local automatic triggering should simultaneously satisfy at least two of the following criteria: load, attitude, or fault duration.

[0057] During a complete operating cycle, the device sequentially performs deployment and leveling, routine monitoring, liquid storage or drainage, in-situ inspection and maintenance, and handling of abnormal operating conditions. At each stage, the underwater control module 21 records status data and control commands, forming a traceable underwater operation log.

[0058] When the liquid volume is at its minimum, the flexible reservoir 11 contracts, the thermal insulation partition 13 falls onto the baffle 18, and the water storage tank 4 is filled with seawater; the underwater control module 21 adjusts the load water volume according to the current mass distribution to maintain the preset suspension state.

[0059] During liquid storage, the storage liquid enters the flexible storage bladder 11, the thermal insulation partition 13 moves with the volume change, the water storage tank 4 discharges seawater, and the load adjustment system 7 synchronously pumps in or discharges compensating seawater to keep the total mass, net buoyancy and attitude of the device within the allowable range.

[0060] During drainage, external seawater enters the water storage tank 4, the thermal insulation partition 13 moves in the opposite direction and assists the flexible storage bladder 11 in draining the liquid, and the load adjustment system 7 adjusts in the opposite direction according to the mass compensation requirements.

[0061] When the temperature of the storage liquid approaches the preset low temperature threshold, the active heating layer is activated in a controlled manner, and the phase change energy storage layer absorbs some of the heat. When there is an external low temperature shock or the active heating is suspended, the phase change energy storage layer releases latent heat to delay the temperature drop of the storage liquid.

[0062] Compared with the prior art, the outstanding innovation of this invention lies in configuring the isobaric liquid storage module in a deep-sea suspended operation body with active load adjustment, attitude monitoring, remote control, underwater docking and emergency release capabilities, so that the device can form a complete underwater operation link around deployment, operation, maintenance and emergency response.

[0063] 1. Closed-loop load adjustment and the buoyancy-center of gravity configuration work together to maintain suspension depth and spatial attitude under conditions of changes in liquid volume and ocean current disturbance, and reduce mooring alternating load.

[0064] 2. Comprehensive online monitoring of attitude, depth, mooring load, and liquid storage status provides real-time data for remote control, fault diagnosis, and safety decision-making.

[0065] 3. In case of mooring anomalies, follow the sequence of "load adjustment and unloading - attitude recovery - conditional release" to quickly release the mooring and maintain safe levitation, thereby improving the safety redundancy of underwater operations.

[0066] 4. The underwater docking interface supports underwater robots or work tools in carrying out detection, communication, control takeover, fluid connection and component maintenance, reducing overall recovery and diver operations.

[0067] 5. Flexible storage tanks, isobaric water tanks, and movable partitions serve as supporting liquid storage structures to achieve physical isolation and volume compensation between seawater and the stored liquid, thereby reducing the risk of pollution.

[0068] 6. The active heating and phase change energy storage structure enhances the flow protection capability of low-temperature sensitive liquids without changing the core technical attributes of the device, which is to be used for underwater suspended operation and maintenance.

[0069] 7. The device does not rely on large-scale seabed foundation treatment, has the ability to be transferred and reused, and can be used in deep-sea oil and gas fields, seabed energy stations or other scenarios that require underwater suspended liquid storage and in-situ operation and maintenance.

[0070] This invention enables underwater levitation, attitude control, mooring safety, docking and maintenance, and supporting liquid storage functions to work together through the above-mentioned structure and control method.

[0071] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. An underwater isobaric suspension oil and liquid storage device, characterized in that, include: The main underwater operation unit is suspended above the seabed and is equipped with a buoyancy chamber, a load adjustment chamber, a counterweight chamber, a mooring system, an attitude monitoring module, an underwater control module, and an underwater docking interface. The buoyancy chamber is located on the upper part of the underwater working body and is used to provide structural buoyancy; the counterweight chamber is located on the lower part of the underwater working body and is used to lower the center of gravity. The buoyancy chamber and the counterweight chamber work together to form an attitude-stable configuration with the center of buoyancy higher than the center of gravity. The loading chamber is equipped with a loading system, which includes a seawater pump, a control valve, and an inlet / outlet pipe. The system is used to pump seawater in or out according to the control commands of the underwater control module, so as to adjust the mass, net buoyancy, and attitude of the underwater working body. The attitude monitoring module is used to collect information on the attitude, depth, mooring load, and liquid storage status of the underwater operating entity. The underwater control module is communicatively connected to the attitude monitoring module and the load adjustment system, and is used to control the load adjustment system in a closed loop based on the information. The underwater control module performs unified clock synchronization, range normalization, outlier removal, and multi-source consistency verification on the sensor data of the attitude monitoring module. It identifies sensor drift or failure through attitude-depth-bottom height cross-estimation, fluid mass conservation verification, and mooring load residual analysis. It also forms three-way liquid storage volume estimation through inlet / outlet flow rate integration, thermal insulation baffle displacement, and flexible reservoir deformation, and performs cross-verification. When some sensors are abnormal, the abnormal channel is isolated, the control state is reconstructed based on the remaining effective sensors, and degraded control is executed to keep the net buoyancy, suspension depth, bottom height, attitude deviation, and mooring load of the device within the corresponding preset range. The mooring system includes a quick release device, a mooring cable, and a seabed anchor installed on the underwater working body. The quick release device can disconnect the underwater working body from the mooring cable according to a remote release command or an abnormal load trigger command. The underwater docking interface is used to detachably dock with underwater robots, remotely operated vehicles, or underwater work tools to perform status detection, control communication, fluid pipeline connection, or component maintenance. The underwater operation body is also equipped with a water storage tank and an oil storage tank as supporting liquid storage modules. The water storage tank is connected to the external seawater at the same pressure, and the oil storage tank includes a flexible reservoir and is connected to the external liquid delivery system through inlet / outlet pipes.

2. The underwater isobaric suspension oil and liquid storage device as described in claim 1, characterized in that, The attitude monitoring module includes: at least two sets of inertial measurement units located on the top of the underwater working body and near the central axis; at least two depth or water pressure sensors spaced apart along the height direction of the underwater working body; mooring tension sensors located between each quick release device and its corresponding mooring cable; a distributed fiber optic strain sensor array laid along the axial and circumferential directions of the underwater working body's outer shell; flow and pressure sensors located in the inlet / outlet pipes and inlet / outlet pipes; liquid level or differential pressure sensors located in the load adjustment tank; temperature, leakage, deformation, displacement, and docking status sensors located in the flexible storage tank, thermal insulation bulkhead, water storage tank, and underwater docking interface; and a current sensor and an acoustic positioning and communication component located on the upper part of the underwater working body, the acoustic positioning and communication component including an upper acoustic transponder and a bottom elevation meter facing the seabed.

3. The underwater isobaric suspension oil and liquid storage device as described in any one of claims 1 to 2, characterized in that, The mooring system also includes a gravity anchor; the underwater control module performs load adjustment and unloading when the mooring tension exceeds a first threshold, and triggers the quick release device when the mooring tension exceeds a second threshold or when a remote emergency command is received.

4. The underwater isobaric suspension oil and liquid storage device as described in any one of claims 1 to 2, characterized in that, The underwater docking interface includes at least two of the following: a mechanical guide, a locking part, a wet-plug communication connection part, and a fluid connection part, and is used for underwater robots to perform inspections, parameter downloads, control takeovers, liquid transfers, or component replacements.

5. The underwater isobaric suspension oil and liquid storage device as described in any one of claims 1 to 2, characterized in that, A heat-insulating partition that can move up and down is provided between the water storage tank and the oil storage tank. The flexible storage bladder physically isolates the stored liquid from the seawater, and the water storage tank discharges or draws in seawater when the stored liquid enters or exits.

6. The underwater isobaric suspension oil and liquid storage device as described in claim 5, characterized in that, The oil storage tank is equipped with a baffle to limit the downward movement of the thermal insulation partition; during operation, the hydraulic pressure inside the flexible reservoir is higher than the water pressure inside the water storage tank, so that the flexible reservoir remains in an outward convex state.

7. The underwater isobaric suspension oil and liquid storage device as described in claim 5, characterized in that, The thermal insulation partition or the fixed partition at the bottom of the oil storage tank includes an active heating layer and a phase change energy storage layer. The underwater control module controls the active heating layer according to the liquid temperature, and the phase change energy storage layer absorbs or releases heat.

8. A method for operating an underwater isobaric suspension oil and liquid storage device as described in any one of claims 1 to 7, characterized in that, include: After deployment, attitude, depth, and mooring load information are collected; The system controls the intake and discharge of seawater based on the collected information, so that the device maintains the preset suspension depth, net buoyancy and attitude. When the storage fluid enters or exits, the loading water volume is adjusted synchronously according to the change in the mass of the storage fluid; it can dock with underwater robots or underwater work tools through the underwater docking interface to perform inspection, maintenance or fluid transfer.

9. The operating method as described in claim 8, characterized in that, Also includes: When the attitude deviation or mooring load exceeds the warning threshold, the load adjustment system is first controlled to perform attitude recovery or mooring unloading. When recovery fails, the mooring load exceeds the release threshold, or a remote emergency command is received, the quick release device is triggered. After release, the load water volume is adjusted based on attitude and depth information to bring the device into a preset safe suspension state and send positioning and status information.

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