A deep-sea underwater suspended oil and liquid storage device and underwater oil storage method

Abstract

A deep-sea underwater suspended oil and liquid storage device and its underwater oil storage method adopts a layered tank structure with a trim tank, a flexible oil storage tank, and a water storage tank arranged from top to bottom. The trim tank dynamically adjusts the net buoyancy of the device by inletting / discharging seawater, reducing the load on the mooring system; the oil storage tank adopts a flexible storage bladder to adapt to volume changes and is linked to the water storage tank by a movable composite insulation partition. The partition includes an active heating layer and a phase change material layer: when the oil temperature is too low, the active heating layer directionally heats the crude oil, and the phase change layer absorbs the escaped heat and releases latent heat to buffer the temperature drop when the external low temperature impacts, thereby achieving dynamic temperature control. The device is fixed by gravity anchor mooring and equipped with multiple types of sensors to monitor the tank posture, stress, oil temperature, and leakage status in real time. The present invention solves the problems of oil storage tank deformation, high-condensate oil insulation, and mooring stability in deep-water high-pressure environments. It has the characteristics of low construction cost, strong environmental adaptability, and efficient operation and maintenance. It is suitable for the safe storage and transportation of deep-sea oil and gas resources.

Description

Technical Field

[0001] The present invention relates to marine oil and gas development and marine engineering technology, and in particular to a deep-sea underwater suspended oil and liquid storage device and an underwater oil storage method thereof. Background Art

[0002] Currently, deepwater oilfield development primarily relies on floating storage and offloading (FSOs), typically including floating storage and offloading (FSOs), semisubmersible platforms, and SPAR platforms. FSOs, due to their flexibility and adaptability, have become the most widely used deepwater oil storage model. However, they are susceptible to environmental influences and place high demands on mooring systems, with the key mooring equipment being single-point mooring systems.

[0003] Existing underwater oil storage technologies mainly include two structural forms: gravity-based bottom-mounted and underwater suspended. Gravity-based bottom-mounted oil storage devices are bulky, have high construction costs, and poor maneuverability. They are only suitable for shallow water areas, and usually require the seabed foundation to be processed before deployment. The construction period is long and the technology is complex. In contrast, underwater suspended oil storage devices have the advantages of relatively light structure, low construction and operating costs, and easy deployment, making them more economical. However, current suspended oil storage devices still face many challenges in deep-sea applications: their mooring systems need to withstand large buoyancy loads, which increases the difficulty of design and maintenance; at the same time, the water pressure in deep-water environments increases significantly, and the oil storage tanks and insulation structures are prone to deformation or failure. Especially in high-viscosity oil storage scenarios, the insulation problem is particularly prominent, which seriously limits the promotion and application of this technology in the deep sea.

[0004] It should be noted that the information disclosed in the above background technology section is only used to understand the background of this application, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0005] The main purpose of the present invention is to overcome the defects existing in the above-mentioned background technology and provide a deep-sea underwater suspended oil and liquid storage device and an underwater oil storage method thereof.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect of the present invention, a deep-sea underwater suspended oil and liquid storage device comprises:

[0008] The inner cavity of the oil and liquid storage tank is divided from top to bottom into a trim tank, an oil storage tank and a water storage tank, among which:

[0009] The trimming tank is equipped with a trimming system for adjusting the overall net buoyancy of the device by inletting / discharging seawater;

[0010] The oil storage tank includes a flexible storage bag for containing oil;

[0011] A movable insulation partition is provided between the oil storage tank and the water storage tank, and the insulation partition floats up and down with the volume change of the oil storage tank; the insulation partition is a multi-layer composite structure, including an active heating layer close to the oil storage tank and a phase change material layer close to the water storage tank. When the oil temperature is lower than a preset value, the active heating layer is controlled to start to directionally heat the crude oil in the oil storage tank, and the heat emitted by the active heating layer to the water storage tank is stored in the phase change material layer to prevent heat from escaping to the external water body. When the phase change material layer impacts the external low-temperature water body, it releases the phase change latent heat to buffer the external low temperature;

[0012] The oil and liquid storage tanks are connected to the seabed by anchoring via a mooring system;

[0013] Multi-type sensor system for real-time monitoring of oil and liquid storage tank posture, stress and strain, oil temperature and leakage status.

[0014] In a second aspect of the present invention, an underwater oil storage method using the deep-sea underwater suspended oil and liquid storage device comprises:

[0015] In the initial state, there is no oil in the flexible storage bladder, the water storage tank is filled with seawater, and the insulation partition is close to the top of the oil storage tank;

[0016] During oil storage, crude oil is injected into the flexible storage bag through the inlet / outlet pipes. The volume of the oil tank increases, pushing the insulation baffle downwards. The seawater in the water tank is discharged, and the load adjustment system pumps in seawater to keep the total mass constant.

[0017] When discharging oil, seawater enters the water storage tank and pushes the insulation baffle upward, squeezing the flexible storage bag to discharge the oil. The load adjustment system discharges seawater to keep the total mass constant.

[0018] When the oil temperature is lower than the preset value, the active heating layer of the thermal insulation partition is controlled to start to directionally heat the crude oil in the oil storage tank, and the heat emitted by the active heating layer to the water storage tank side is stored in the phase change material layer of the thermal insulation partition to prevent heat from escaping to the external water body. The phase change material layer releases the latent heat of phase change when impacted by the external low-temperature water body, thereby buffering the external low temperature.

[0019] The present invention has the following beneficial effects:

[0020] The present invention proposes a deep-sea underwater suspended oil and liquid storage device. Through the layered oil and liquid storage tank design, combined with the load adjustment system to dynamically adjust the net buoyancy, the design difficulty and maintenance cost of the mooring system are significantly reduced; a flexible storage capsule and a movable composite insulation baffle structure are designed, and an active heating layer is integrated to directionally heat the high-freezing point crude oil and a phase change material layer to buffer the external low-temperature impact, effectively solving the deformation and insulation problems of the oil storage tank under deep-water high-pressure environment, and combining mechanical strength, energy efficiency and adaptability to extreme environments; equipped with a multi-type sensor system to monitor the tank posture, stress and strain, oil temperature and leakage status in real time, further constructing a digital twin monitoring system, and realizing risk warning and operation and maintenance decision support through load inversion and near-real-time mechanical simulation, to ensure the safe operation of the device and extend its service life. The overall solution of the present invention does not require seabed foundation pretreatment, has the advantages of strong mobility, low construction cost, and reusability, is compatible with the existing technology system, and provides a reliable technical path for the efficient, safe, and economical storage and transportation of deep-sea oil and gas resources and large-scale commercial development.

[0021] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the overall installation of underwater oil storage equipment according to an embodiment of the present invention.

[0023] Figure 2 This is a schematic structural diagram of underwater oil storage equipment according to an embodiment of the present invention.

[0024] Figure 3 Schematic diagram of the structure of the thermal insulation partition according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope of the present invention and its application.

[0026] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for both fixing and coupling or communication.

[0027] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and 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, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0029] To address the shortcomings of traditional floating storage and offloading (FSO) systems, this invention proposes a deep-sea underwater suspended oil and liquid storage device that can replace FSOs. This device effectively addresses challenges such as tank deformation, high-pour point oil insulation, and mooring stability in high-pressure deepwater environments. It enables economical, efficient, and safe storage and transportation of oil in complex deep-sea environments, providing reliable technical support for deep-sea oil and gas development.

[0030] See Figure 1 and Figure 2The embodiment of the present invention provides a deep-sea underwater suspended oil and liquid storage device, comprising an oil and liquid storage tank body 1, the inner cavity of which is divided from top to bottom into a load trimming tank 2, an oil storage tank 3 and a water storage tank 4, wherein: the load trimming tank 2 has a built-in load trimming system 5 for adjusting the overall net buoyancy of the device by inlet / outlet of seawater; the load trimming tank 2 and the oil storage tank 3 can be separated by a fixed partition 6; the oil storage tank 3 includes a flexible storage bag 7 for containing oil and liquid; a movable insulation partition 8 is provided between the oil storage tank 3 and the water storage tank 4, and the insulation partition 8 floats up and down with the volume change of the oil storage tank 3 (the insulation partition 8 does not need to be strictly sealed, but the radius is the same as the storage tank 3). The inner diameter of the tank is adapted, preferably as close to the inner diameter of the storage tank as possible); the thermal insulation partition 8 is a multi-layer composite structure, including an active heating layer close to the oil storage tank 3 and a phase change material layer close to the water storage tank 4. When the oil temperature is lower than a preset value, the active heating layer is controlled to start to directionally heat the crude oil in the oil storage tank 3, and the heat transferred from the active heating layer to the water storage tank 4 is stored in the phase change material layer to prevent heat from escaping to the external water body. The phase change material layer releases the latent heat of phase change when impacted by the external low-temperature water body, buffering the external low temperature; the oil and liquid storage tank body 1 is anchored to the seabed through a mooring system. The oil and liquid storage device is also equipped with multiple types of sensor systems for real-time monitoring of the posture, stress and strain, oil temperature and leakage status of the oil and liquid storage tank body 1.

[0031] In some embodiments, the load trimming system 5 includes a load trimming tank inlet / outlet pipe 12, which is connected to external seawater to eliminate water pressure differences and maintain a constant total mass of the device by pumping seawater.

[0032] In some embodiments, the thermal insulation partition 8 includes, from top to bottom, a rigid plate 81 , an active heating layer 82 , a first flexible thermal insulation layer 83 , a phase change material layer 84 , and a second flexible thermal insulation layer 85 .

[0033] In some embodiments, the outer shell of the oil and liquid storage tank body 1 is a steel plate concrete composite structure, including inner and outer steel plates, core concrete, shear connectors arranged at the steel-concrete interface, and steel webs connecting the inner and outer steel plates.

[0034] In some embodiments, the sensor system includes: an IMU attitude sensor 16 and a water pressure gauge 17, which are arranged on the top of the tank to monitor the attitude and water pressure; an optical fiber sensor 18, which is arranged in the middle of the tank to monitor stress and strain; an inlet and outlet flow rate sensor 19 arranged on the water storage tank inlet / outlet pipe 15 and an inlet and outlet oil flow rate sensor 20 arranged on the inlet / outlet oil pipe 13; an oil leakage monitoring sensor 21, a temperature sensor 22 and a flexible sensor 23, which respectively monitor the leakage of the oil storage tank 3, the oil temperature and the deformation of the flexible storage bag 7.

[0035] In some embodiments, the oil inlet / outlet pipe 13 is installed on the central axis of the tank body through a guide mechanism 14 , can be raised and lowered along the axial direction, and is connected to the flexible storage bag 7 .

[0036] In some embodiments, the mooring system includes a quick release 9, a mooring cable 10 and a gravity anchor 11. The two ends of the mooring cable 10 are respectively connected to the quick release 9 and the gravity anchor 11. The quick release 9 is arranged on the oil and liquid storage tank body 1 for emergency separation.

[0037] In some embodiments, the deep-sea underwater suspended oil and liquid storage device also includes a digital twin monitoring system, which inverts the load based on sensor data and simulates the structural mechanical behavior in near real time; the digital twin monitoring system includes: a load inversion algorithm, which inverts the global load of the tank based on sensor data; a near-real-time mechanical simulation algorithm, which evaluates the mechanical behavior of the tank, fatigue fracture of the flexible storage bag 7 and pipeline wear.

[0038] An embodiment of the present invention further provides an underwater oil storage method using the deep-sea underwater suspended oil and liquid storage device of any of the aforementioned embodiments, comprising:

[0039] In the initial state, there is no oil in the flexible storage bag 7, the water storage tank 4 is filled with seawater, and the thermal insulation partition 8 is close to the top of the oil storage tank 3;

[0040] When storing oil, crude oil is injected into the flexible storage bag 7 through the inlet / outlet pipes. The volume of the oil storage tank 3 increases, pushing the insulation partition 8 downward. The seawater in the water storage tank 4 is discharged, and the load adjustment system 5 pumps in seawater to keep the total mass constant.

[0041] When discharging oil, seawater enters the water storage tank 4, pushing the thermal insulation partition 8 upward, squeezing the flexible storage bag 7 to discharge the oil, and the load adjustment system 5 discharges seawater to keep the total mass constant;

[0042] When the oil temperature is lower than the preset value, the active heating layer of the thermal insulation partition 8 is controlled to start in a directionally heated manner to heat the crude oil in the oil storage tank 3, and the heat emitted by the active heating layer to the side of the water storage tank 4 is stored in the phase change material layer of the thermal insulation partition 8 to prevent heat from escaping to the external water body. The phase change material layer releases the latent heat of phase change when impacted by the external low-temperature water body to buffer the external low temperature.

[0043] In some embodiments, the underwater oil storage method also includes: real-time monitoring of the tank status through a sensor system, including the posture, stress and strain, oil temperature and leakage status of the oil and liquid storage tank; based on the tank status data monitored in real time by the sensor system, the following operations are performed synchronously through the digital twin monitoring system: inverting the global load distribution of the oil and liquid storage tank 1 based on the load inversion algorithm; evaluating the stress and strain behavior of the tank shell, the fatigue fracture risk of the flexible storage bag 7 and the wear of the inlet / outlet oil pipe 13 through a near-real-time mechanical simulation algorithm; and generating maintenance decision recommendations or risk warnings based on the simulation results to ensure the safe operation of the device.

[0044] The innovative design of the present invention solves the problems of oil storage tank deformation, high-condensate oil insulation and mooring stability under deep-water high-pressure environment. It has the characteristics of low construction cost, strong environmental adaptability and efficient operation and maintenance, and is suitable for the safe storage and transportation of deep-sea oil and gas resources.

[0045] The following further describes specific embodiments of the present invention and its working principle.

[0046] like Figure 1 and Figure 2 As shown, a deep-sea underwater suspended oil and liquid storage device comprises an oil and liquid storage tank 1. The inner cavity of the oil and liquid storage tank 1 is arranged from top to bottom as a trim tank 2, an oil storage tank 3, and a water storage tank 4. The positions of the trim tanks 2, 3, and 4 can be adjusted according to specific needs. The trim tank 2 is equipped with a trim system 5. The trim tank 2 and the oil storage tank 3 are separated by a fixed partition 6. The oil storage tank 3 is composed of a flexible storage bladder 7. Between the oil storage tank 3 and the water storage tank 4 is an insulating partition 8, which moves with the ups and downs of the water layer.

[0047] The outer shell of the oil and liquid storage tank 1 is preferably a composite shell structure, but may also be a pure steel or concrete structure. Taking a composite shell structure as an example, the outer shell structure of the oil and liquid storage device is a composite shell structure, specifically a steel plate concrete composite structure, typically consisting of inner and outer steel plates, a concrete core, shear connectors provided at the steel-concrete interface, and a steel web connecting the inner and outer steel plates.

[0048] The shell and the fixed partition 6 of the oil and liquid storage tank body 1 are both composite materials and have the function of heat preservation. The heat preservation partition 8 is composed of phase change heat preservation material and has an active heating system to actively heat the crude oil. Specifically, the composite material is a multi-layer composite structure, including an outer protective layer, an intermediate core heat preservation interlayer and a transition layer; specifically, Figure 3 As shown, the thermal insulation partition 8 is a multi-layer composite structure, which comprises, from top to bottom, a rigid plate 81 , an active heating layer 82 , a first flexible thermal insulation layer 83 , a phase change material layer 84 , and a second flexible thermal insulation layer 85 .

[0049] The oil and liquid storage tank body 1 is provided with a quick release 9, which is connected to a mooring cable 10, and the mooring cable is connected to a gravity anchor 11 on the seabed.

[0050] The trim tank 2 is equipped with an inlet / outlet pipe 12, connecting the seawater inside the trim tank 2 with the external seawater, eliminating any pressure difference between the inside and outside of the trim tank. An oil inlet / outlet pipe 13 is mounted on the central axis of the oil and liquid storage tank 1 via a guide mechanism 14. The oil inlet / outlet pipe 13 can be adjusted up and down along the tank's central axis. An inlet / outlet pipe 15 is installed at the bottom of the water storage tank 4, connecting the water storage tank 4 to the external seawater through the inlet / outlet pipe 15, eliminating any pressure difference between the inside and outside of the water storage tank 4.

[0051] An IMU attitude sensor 16 and a water pressure gauge 17 are provided on the top of the oil and liquid storage tank body 1 to monitor the attitude of the oil and liquid storage tank body 1 and the water pressure on the top of the oil and liquid storage tank body 1. An optical fiber sensor 18 is provided in the middle of the outer shell of the oil and liquid storage tank body 1 to monitor the stress and strain of the oil and liquid storage tank body 1. An inlet and outlet flow rate sensor 19 is provided in the inlet / outlet pipe 15 to detect the flow rate and flow rate of water entering / exiting the water storage tank 4. An inlet and outlet oil flow rate sensor 20 is provided in the inlet / outlet oil pipe 13 to monitor the flow rate and flow rate of crude oil entering / exiting the flexible storage bag 7. An oil leakage monitoring sensor 21 is provided on the fixed partition 6 to monitor whether the flexible storage bag 7 is leaking oil. A temperature sensor 22 is provided on the outside of the flexible storage bag 7 to monitor the crude oil temperature in real time. A flexible sensor 23 is provided on the outside of the flexible storage bag 7 to monitor the deformation of the flexible storage bag 7.

[0052] The oil and liquid storage tank is equipped with a monitoring system based on the concept of digital twins. The system primarily comprises a composite material shell load inversion algorithm and a global structural near-real-time mechanical simulation algorithm, both of which are loaded onto a monitoring terminal 24. The load inversion algorithm is capable of performing high-precision inversion of the global load on the oil and liquid storage tank 1 shell based on sensors. The global structural near-real-time mechanical simulation algorithm is capable of performing near-real-time simulation and assessment of the mechanical behavior and effects of the oil and liquid storage tank 1 shell, fatigue and fracture effects of the flexible bladder 7, and blockage, overpressure, and inner wall wear of the inlet and outlet oil pipes 13 based on sensor data.

[0053] The load-adjusting tanks and water storage tanks are all connected to the external seawater, and there is no pressure difference between the internal and external water. The load-adjusting system ensures that the net buoyancy of the oil and liquid storage device underwater remains unchanged through the operation of filling / draining water according to the working state of the oil and liquid storage device.

[0054] The insulation layer has excellent thermal insulation performance, and the insulation partition 8 has an active heating system. Specifically, the composite material is a multi-layer composite structure, including an outer protective layer, an intermediate core insulation interlayer, and a transition layer. Specifically, the insulation partition 8 is a multi-layer composite structure, which, from top to bottom, comprises a rigid plate, an active heating layer, a first flexible insulation layer, a phase change material layer, and a second flexible insulation layer.

[0055] The outer shell of the oil and liquid storage tank 1 is preferably a composite shell structure, but may also be a pure steel or concrete structure. Taking the composite shell structure as an example, the outer shell structure of the oil and liquid storage device is a composite shell structure, specifically a steel plate concrete composite structure, typically composed of inner and outer steel plates, a concrete core, shear connectors provided at the steel-concrete interface, and a steel web connecting the inner and outer steel plates.

[0056] The sensors can detect in real time the deformation of the flexible storage bag and the oil and liquid storage tank of the oil and liquid storage device, the temperature of the crude oil, and whether the oil storage tank is leaking, thereby ensuring the normal operation of the deep-sea underwater suspended oil and liquid storage device.

[0057] The digital twin system can invert the shell load of the oil and liquid storage tank body 1 in a very short time, simulate the nonlinear strain behavior and effects of the shell, evaluate the posture, behavior, nonlinear fatigue and crack conditions of the flexible storage bag 7, and quickly simulate the wear of the inlet / outlet oil pipe 13 due to overpressure leakage and erosion of sand and gravel in the oil.

[0058] An underwater oil storage method using the deep-sea underwater suspended oil and liquid storage device of the aforementioned embodiment specifically includes the following operating procedures:

[0059] State 1: When the oil storage amount in the flexible storage bag 7 is zero, the space in the oil storage tank 3 is compressed, and the heat-insulating partition 8 is close to the upper fixed partition 6. At this time, the water storage tank 4 is filled with seawater.

[0060] State 2: As crude oil begins to enter the flexible bladder 7 through the inlet / outlet pipes 13, the volume of the oil storage tank 3 increases as the volume of crude oil in the flexible bladder 7 gradually increases. The thermal insulation baffle 8 moves downward, and the seawater in the water tank 4 is discharged into the seawater outside the oil and liquid storage tank 1 through the inlet / outlet pipes 15. At this time, the loading system 5 pumps seawater into the loading system 5, maintaining the total mass of the oil and liquid storage tank 1 unchanged as the crude oil enters the flexible bladder 7. When the volume of crude oil in the flexible bladder 7 reaches the designed volume, the oil intake stops.

[0061] State 3: As crude oil begins to drain from the flexible bladder 7 through the inlet / outlet pipes 13, seawater from the exterior of the oil and liquid storage tank 1 enters the water tank 4 through the inlet / outlet pipes 15. The seawater pushes the insulation baffle 8 upward, gradually reducing the volume of the oil tank 3. The rising seawater within the water tank 4 provides pressure for the crude oil to drain from the flexible bladder 7, allowing it to spontaneously exit the bladder 7. At this point, the load-adjusting system 5 drains the seawater from the load-adjusting tank 2, maintaining the overall mass of the oil and liquid storage tank 1 while the crude oil exits the flexible bladder 7.

[0062] State 4: When the crude oil temperature drops close to the waxing temperature, the insulating baffle 8 actively heats the crude oil to maintain its fluid state. When the oil temperature falls below the preset waxing temperature, the active heating layer of the insulating baffle 8 activates, heating the crude oil through directional heat transfer from the rigid plate to the oil and liquid storage side. Simultaneously, on the other side of the active heating layer, heat flows through the first flexible insulation layer, the phase change material layer, and the second flexible insulation layer, storing the heat in the phase change material layer to prevent it from escaping to the external water. When impacted by the external low-temperature water, the phase change material layer releases the latent heat of phase change and slows the temperature transfer.

[0063] State 5: When crude oil begins to flow into or out of the flexible bladder 7 through the inlet / outlet pipe 13, the flow rate and velocity sensor 20 monitors the flow rate and velocity of crude oil in and out of the flexible bladder 7 in real time. Simultaneously, the flexible sensor 23 monitors the deformation of the flexible bladder 7 in real time; the oil leakage monitoring sensor 21 monitors whether the flexible bladder 7 is leaking; and the temperature sensor 22 monitors the crude oil temperature in real time.

[0064] Compared with the prior art, the present invention has the following significant advantages:

[0065] 1. The present invention designs a deep-sea underwater suspended oil and liquid storage device. Compared with gravity-based bottom-mounted oil storage devices, the deep-sea underwater suspended oil and liquid storage device has low construction cost, good maneuverability, can be used in the deep sea, and does not require advance treatment of the seabed foundation before installation and deployment.

[0066] 2. Compared with existing underwater suspended oil storage devices, the present invention configures a load adjustment system to maintain the overall underwater net buoyancy unchanged in any state, thereby reducing the design difficulty and construction cost of the mooring system.

[0067] 3. This invention not only has excellent thermal insulation performance but also features active heating to prevent the solidification of high-freezing-point crude oil, ensuring production efficiency. By designing a multi-layered thermal insulation baffle structure based on active heating and phase change materials, it achieves a synergistic thermal insulation effect by dynamically regulating the temperature of the oil and liquid storage tanks and passively buffering against low ambient temperatures, while also balancing mechanical strength, energy efficiency, and adaptability to extreme environments.

[0068] 4. In the present invention, each sensor can monitor the deformation of the flexible storage bag, the stress and strain of the oil and liquid storage tank shell, the temperature of the crude oil, and whether the oil storage tank is leaking in real time to ensure the normal operation of the deep-sea underwater suspended oil and liquid storage device.

[0069] 5. In this invention, the digital twin monitoring system can perform local analysis and remote monitoring based on sensor data to assess the mechanical effects of all major components of the oil and liquid storage device. This rapid and accurate monitoring system can assist autonomous equipment and remote decision-making and risk assessment by operators, thereby extending lifespan, reducing risks, and ultimately reducing costs and increasing efficiency.

[0070] 6. The tank shell of the present invention preferably adopts a composite material shell structure, taking into account the requirements of the floating system, significantly improving the load-bearing capacity and durability, and effectively reducing construction costs.

[0071] 7. The solution provided by the present invention is suitable for use as an oil and liquid storage device in the development of deep-sea oil and gas fields. It can be well combined with the existing technical system, providing an effective route to reduce costs and increase efficiency for the large-scale commercial development of deep-sea oil and gas.

[0072] The above description further details the present invention in conjunction with specific / preferred embodiments, and the specific implementation of the present invention should not be construed as being limited to these descriptions. Persons skilled in the art will appreciate that, without departing from the spirit of the present invention, they may make various substitutions or modifications to the described embodiments, and these substitutions or modifications should be considered to fall within the scope of protection of the present invention. Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "preferred embodiments," "examples," "specific examples," or "some examples" indicates that the specific features, structures, materials, or characteristics described in conjunction with such embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Persons skilled in the art may combine and assemble the different embodiments or examples described in this specification, as well as features of different embodiments or examples, without conflicting opinions. 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 may be made herein without departing from the scope of protection of the patent application.

Claims

1. A deep-sea underwater suspended oil and liquid storage device, characterized in that: include: The inner cavity of the oil and liquid storage tank is divided from top to bottom into a trim tank, an oil storage tank and a water storage tank, among which: The trimming tank is equipped with a trimming system for adjusting the overall net buoyancy of the device by inletting / discharging seawater; The oil storage tank includes a flexible storage bag for containing oil; A movable heat-insulating partition is provided between the oil storage tank and the water storage tank, and the heat-insulating partition floats up and down as the volume of the oil storage tank changes; The thermal insulation baffle is a multi-layer composite structure, including an active heating layer near the oil storage tank and a phase change material layer near the water storage tank. When the oil temperature is lower than a preset value, the active heating layer is controlled to start to directionally heat the crude oil in the oil storage tank, and the heat emitted by the active heating layer to the water storage tank is stored in the phase change material layer to prevent heat from escaping to the external water body. The phase change material layer releases phase change latent heat when impacted by external low-temperature water, buffering the external low temperature. The thermal insulation baffle includes, from top to bottom, a rigid plate, an active heating layer, a first flexible thermal insulation layer, a phase change material layer, and a second flexible thermal insulation layer. The oil and liquid storage tanks are connected to the seabed by anchoring via a mooring system; Multi-type sensor system for real-time monitoring of oil and liquid storage tank posture, stress and strain, oil temperature and leakage status.

2. The deep-sea underwater suspended oil and liquid storage device according to claim 1, characterized in that: The load trimming system includes an inlet / outlet pipe of the load trimming tank, which is connected to the external seawater to eliminate the water pressure difference and keeps the total mass of the device constant by pumping seawater.

3. The deep-sea underwater suspended oil and liquid storage device according to any one of claims 1 to 2, characterized in that: The shell of the oil and liquid storage tank body is a steel plate concrete composite structure, including inner and outer steel plates, core concrete, shear connectors arranged at the steel-concrete interface and steel webs connecting the inner and outer steel plates.

4. The deep-sea underwater suspended oil and liquid storage device according to any one of claims 1 to 2, characterized in that: The sensor system comprises: IMU attitude sensor and water pressure gauge are installed on the top of the tank to monitor attitude and water pressure; Fiber optic sensor, installed in the middle of the tank to monitor stress and strain; Flow rate sensors are installed on the oil inlet / outlet pipes and water tank inlet / outlet pipes; The oil leakage monitoring sensor, temperature sensor and flexible sensor monitor the oil tank leakage, oil temperature and flexible storage bag deformation respectively.

5. The deep-sea underwater suspended oil and liquid storage device according to claim 4, characterized in that: The oil inlet / outlet pipe is installed on the central axis of the tank body through a guide mechanism, can be adjusted to rise and fall along the axial direction, and is communicated with the flexible storage bag.

6. The deep-sea underwater suspended oil and liquid storage device according to any one of claims 1 to 2, characterized in that: The mooring system includes a quick release, a mooring cable and a gravity anchor. The two ends of the mooring cable are respectively connected to the quick release and the gravity anchor. The quick release is arranged on the oil and liquid storage tank body for emergency release.

7. The deep-sea underwater suspended oil and liquid storage device according to any one of claims 1 to 2, characterized in that: It also includes a digital twin monitoring system that inverses loads based on sensor data and simulates structural mechanical behavior in near real time; The digital twin monitoring system includes: Load inversion algorithm, inverting the global load of the tank based on sensor data; Near-real-time mechanical simulation algorithms are used to evaluate tank mechanical behavior, flexible bladder fatigue fracture, and pipeline wear.

8. An underwater oil storage method using the deep-sea underwater suspended oil and liquid storage device according to any one of claims 1 to 7, characterized in that: include: In the initial state, there is no oil in the flexible storage bladder, the water storage tank is filled with seawater, and the insulation partition is close to the top of the oil storage tank; During oil storage, crude oil is injected into the flexible storage bag through the inlet / outlet pipes. The volume of the oil tank increases, pushing the insulation baffle downwards. The seawater in the water tank is discharged, and the load adjustment system pumps in seawater to keep the total mass constant. When discharging oil, seawater enters the water storage tank and pushes the insulation baffle upward, squeezing the flexible storage bag to discharge the oil. The load adjustment system discharges seawater to keep the total mass constant. When the oil temperature is lower than the preset value, the active heating layer of the thermal insulation partition is controlled to start to directionally heat the crude oil in the oil storage tank, and the heat emitted by the active heating layer to the water storage tank side is stored in the phase change material layer of the thermal insulation partition to prevent heat from escaping to the external water body. The phase change material layer releases the latent heat of phase change when impacted by the external low-temperature water body, thereby buffering the external low temperature.

9. The method according to claim 8, wherein Also includes: Real-time monitoring of tank status through sensor systems, including oil and liquid storage tank posture, stress and strain, oil temperature and leakage status; Based on the tank status data monitored in real time by the sensor system, the following operations are performed synchronously through the digital twin monitoring system: Inverse the global load distribution of the oil and liquid storage tank based on the load inversion algorithm; Use near-real-time mechanical simulation algorithms to assess the stress-strain behavior of the tank shell, the fatigue fracture risk of the flexible bladder, and the wear of the inlet and outlet oil pipes; Combined with simulation results, maintenance decision recommendations or risk warnings are generated to ensure the safe operation of the device.

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