Offshore double-ship side-by-side mooring system and method

Abstract

The invention discloses an offshore double-ship side-by-side mooring system and method. The offshore double-ship side-by-side mooring system comprises a main ship anchoring system, a power positioning system and a main ship mooring system, wherein the main ship anchoring system is used for fixing the position of a main ship through an anchoring system or the power positioning system; the auxiliary ship berthing and mooring dynamic compensation system is connected with the auxiliary ship and the main ship through a mooring rope; the dynamic compensation system for berthing and mooring comprises a fender assembly, a main ship and an auxiliary ship, wherein the fender assembly is arranged on the broadside of the main ship or the auxiliary ship and is made of hollow barrel-shaped elastic rubber; the mooring cable group comprises a head cable, a tail cable and a middle cable; and the mooring rope tensioner is connected to the tail end of the mooring rope group and is used for dynamically adjusting the tension of the mooring rope. The method is suitable for sand conveying, and after the fracturing ship (main ship) is berthed, the sand conveying ship (auxiliary ship) conveys the propping agent side by side. And in the offshore oil fracturing operation, the sand conveying efficiency can be improved stably, and operation interruption is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a double-ship parallel berthing system and method, belonging to the technical field of ship berthing. BACKGROUND

[0002] In marine engineering and resource development, double-ship parallel operation is a common but challenging task. When offshore ships are parallel supplied, due to the water dynamic force between the two ships, dynamic interference problems often occur between the supply ship and the receiving ship, causing deviation of the relative position of the two ships, and seriously affecting the success rate of parallel supply operation. The existing parallel berthing method usually relies on traditional mooring fixing methods or simple ship collision avoidance devices, which still cannot effectively solve the problem of relative motion of ships under dynamic external force, so that the two ships still have certain sway and displacement when berthing, especially in complex sea conditions, the contact stability and operation safety between the two ships still have obvious defects, which is not conducive to the continuous transportation of supply. Therefore, it is necessary to study a double-ship parallel berthing system and method to solve the instability problem of existing ship parallel supply, and the present application is proposed to realize stable transportation of materials between two ships, especially sand transportation. SUMMARY

[0003] The purpose of the present application is to provide a double-ship parallel berthing system and method, i.e. a method for berthing, mooring and operation between fracturing ships and sand-carrying ships, which ensures the safe berthing and reliable separation of the two ships through the coordinated work of the berthing mooring dynamic compensation system and the automatic mooring machine. The present application combines automatic control equipment and operation process, which can effectively solve the problem of relative motion of double ships in complex sea conditions, and significantly improve the safety and efficiency of double-ship parallel operation.

[0004] In the present application, the fracturing ship is stably berthed by the main ship anchor mooring system (anchor mooring or dynamic positioning system), and the sand-carrying ship is connected to the main ship by mooring and precisely berthed by the berthing mooring dynamic compensation system.

[0005] The berthing mooring dynamic compensation system provided by the present application comprises: fender assembly: arranged on the side of the main ship or the auxiliary ship, composed of a hollow barrel-shaped elastic rubber, which can absorb the relative motion of the ship in complex sea conditions and reduce displacement and sway; mooring cable group: including bow cable, stern cable and intermediate cable; mooring cable tensioner: connected to the end of the mooring cable group, used for dynamically adjusting the cable tension.

[0006] Preferably, the mooring cable tensioner comprises: energy storage tank, adopting an air energy storage hydraulic transmission structure, configured to maintain the tension change amplitude within a preset range in the working stroke; a liquid cylinder in fluid communication with the energy tank, and a telescopic rod reciprocating under the drive of the liquid cylinder; a guiding device for transmitting the top tension of the telescopic rod to the cable.

[0007] The energy tank in the present application can adjust the tension of the cable according to preset parameters and automatically adjust to maintain a stable connection state when the sea conditions change.

[0008] Preferably, the guiding device comprises a guide wheel and a guide column. The guide wheel is mounted on the top of the guide column for receiving and transmitting the top tension of the telescopic rod to the cable, and the effective tensioning and dynamic compensation of the cable are realized through the mooring line tensioner. One side of the guide column is connected with the telescopic rod, and the lower part is placed in the deck guide slot for limiting the movement direction of the telescopic rod, i.e. the telescopic rod extends to push the guide column to the designated position. The guide wheel comprises a lower guide column and a peripheral guide groove to ensure that the cable remains stable and is not easy to deviate during guiding.

[0009] The guide wheel guides the cable into the correct path of the mooring line tensioner through the peripheral guide groove during the cable launching process, avoiding the jamming or damage of the cable due to deviation; the guide wheel cooperates with the telescopic rod of the mooring line tensioner to ensure that the cable can move smoothly and maintain appropriate tension when entering the mooring line tensioner. In addition, the guide wheel also has wear resistance and can operate stably for a long time under high pressure and dynamic load.

[0010] The rotating shaft of the guide wheel adopts a precision bearing to reduce friction resistance and ensure flexible rotation; the width and depth of the peripheral guide groove are accurately calculated to facilitate the guidance of the cable while avoiding excessive wear.

[0011] The guide wheel is equipped with anti-loosening bolts and sealing rings to prevent faults caused by vibration or water vapor intrusion.

[0012] In the present application, the telescopic rod is a telescopic metal rod driven by hydraulic pressure.

[0013] The working principle of the mooring line tensioner is that energy is stored and released by compression and expansion of gas, when the hydraulic pump in the hydraulic system supplies oil to the hydraulic cylinder, the liquid will compress the gas, increase the pressure inside the energy storage tank. The hydraulic cylinder is a device for converting hydraulic energy into mechanical energy, which is composed of cylinder body, telescopic rod, sealing element and other parts. When the liquid flows from the energy storage tank into the hydraulic cylinder, the telescopic rod is pushed to move by the pressure of the liquid, so as to realize the work of the hydraulic cylinder. After the bow and stern cables of the two ships are connected, the energy storage tank is pressurized to a preset value, the gas pressure in the tank pushes the liquid out through the pipe flow circuit, and drives the hydraulic cylinder to fully extend the telescopic rod.

[0014] On the basis of the docking mooring dynamic compensation system, the application further provides a double-ship parallel docking system at sea, comprising: A main ship anchoring system configured to fix the position of the main ship through an anchoring system or a dynamic positioning system; A secondary ship mooring system comprising the docking mooring dynamic compensation system, connecting the secondary ship and the main ship through a cable; Further, the application further provides a double-ship parallel docking method at sea, comprising the following steps: S1, the main ship is fixed at the working position through the main ship anchoring system; S2, the secondary ship approaches the side of the main ship and maintains a safe distance; S3, the secondary ship is connected to the main ship through a mooring line, and docking is realized based on the docking mooring dynamic compensation system.

[0015] In step S3, the docking step realized by using the docking mooring dynamic compensation system is as follows: 1) Start the mooring line tensioner, pressurize the energy storage tank to a preset pressure value, and fully extend the telescopic rod; 2) After guiding each mooring line into the corresponding guide wheel, tighten the mooring line to a preset safe tension value; 3) Synchronously adjust the tension of each mooring line to make the secondary ship tightly adhere to the fender assembly of the main ship.

[0016] After step 3), the following steps are further included: Real-time monitoring of environmental load and relative displacement of the ship, and dynamically adjusting the nitrogen pre-charge pressure of the energy storage tank to 60%-80% of the system working pressure, the system working pressure is 20 MPa, and the pre-charge pressure is 12-16 MPa.

[0017] The main ship is a fracturing ship, the secondary ship is a sand transport ship, and the method is used to realize continuous sand transport operation between the fracturing ship and the sand transport ship during offshore fracturing operation.

[0018] The application effectively buffers external force interference by using a dynamic compensation system for berthing (especially a mooring line tensioner and a fender), reduces the relative movement amplitude of the two ships, and greatly reduces the amplitude of the swing in complex sea conditions. By pre-setting the tension value and the synchronous tightening mechanism, the risk of cable breakage or ship collision is avoided, ensuring the safety of the operation (such as material transfer during sand delivery). The automatic mooring machine and the dynamic compensation system shorten the berthing time and are suitable for high-frequency operations (such as ocean resource development).

[0019] The feature of the offshore double-ship parallel berthing method of the application lies in how to realize stability by using a dynamic compensation system for berthing. Dynamic compensation process: when external forces (such as surges) cause the secondary ship to move relative to the primary ship, the change in mooring line tension triggers the response of the mooring line tensioner. The energy storage tank drives the hydraulic cylinder to adjust the length of the telescopic rod through air energy storage (storage of air pressure energy) and hydraulic transmission, thereby fine-tuning the tension of the cable. For example, when the tension increases, the telescopic rod retracts to release the length; when the tension decreases, the telescopic rod extends to tighten the cable.

[0020] Cooperative work: the fender provides primary buffering (absorbing instantaneous impact), the mooring line transmits external force, and the mooring line tensioner performs real-time compensation. The whole process is monitored by an automatic system, combined with sensor (such as tension sensor) feedback data, to realize closed-loop control.

[0021] The method of the application is suitable for sand delivery: after the fracturing ship (primary ship) is parked, the sand delivery ship (secondary ship) is parallelly parked to transfer proppants. In offshore oil fracturing operations, stable parallel parking can improve sand delivery efficiency and reduce operation interruptions. It can also be used for other marine engineering, such as ship supply and personnel transfer.

[0022] The application has the following beneficial technical effects: Improved stability: the dynamic compensation mechanism reduces the relative movement amplitude of the two ships; Enhanced safety: the fender and the pre-set tension value avoid the risk of collision; the automatic mooring machine reduces human error; Efficiency optimization: the operation time is shortened to within 20 minutes; suitable for high-frequency operations (such as sand delivery multiple times a day).

[0023] Cost-effective: system components (such as flexible rubber fenders) are durable and easy to maintain, with a service life of ≥5 years, reducing long-term operating costs. BRIEF DESCRIPTION OF DRAWINGS Figure 1 It is a schematic diagram of the overall structure of the dynamic compensation system for berthing of the application.

[0025] Figure 2 It is a schematic diagram of the overall structure of the mooring line tensioner of the application.

[0026] Figure 3 It is a schematic diagram of the energy storage tank of the application.

[0027] Figure 4 Flow chart of the double-ship parallel berthing method. DETAILED DESCRIPTION

[0028] The experimental methods used in the following examples are conventional methods unless otherwise specified.

[0029] The materials, reagents, etc. used in the following examples can be obtained commercially unless otherwise specified.

[0030] Figure 1 The overall structure of the berthing mooring dynamic compensation system provided by the present application is shown in the figure, and the main structure includes: a fracturing ship body 1, a sand transportation ship body 2, a cable pile 3, an energy storage tank 7, a guide groove 5, a guide wheel 6, an extension rod 4, an automatic mooring machine 8, a fender assembly 9, a deck 10, and a cable 11.

[0031] As shown in Figure 1 , the berthing mooring dynamic compensation system provided by the present application includes a fender assembly, a mooring cable group, and a mooring tensioner, wherein the fender assembly 9 is arranged on the side of the fracturing ship body 1 and is composed of a hollow barrel-shaped elastic rubber, which can absorb the relative movement of the ship in complex sea conditions and reduce displacement and sway. The mooring cable group includes a bowline, a stern line, and a middle line (cable 11), which are made of high-strength and corrosion-resistant materials to cope with salt mist and moisture corrosion in the marine environment. The mooring tensioner is connected to the end of the mooring cable group and is used for dynamically adjusting the cable tension.

[0032] As shown in Figure 1 , Figure 2 and Figure 3 , the mooring tensioner includes an energy storage tank 7, a hydraulic cylinder 12, an extension rod 4, and a guide device, wherein the energy storage tank 7 adopts an air energy storage hydraulic transmission structure and is configured to maintain the tension change amplitude within a preset range during the working stroke, the hydraulic cylinder 12 is in fluid communication with the energy storage tank 7, the extension rod 4 reciprocates under the drive of the hydraulic cylinder 12, and the guide device transmits the top tension of the extension rod 4 to the cable, and the extension rod 4 is a telescopic metal rod driven by hydraulic pressure. The energy storage tank 7 can adjust the tension of the cable according to the preset parameters and automatically adjust to maintain a stable connection state when the sea conditions change.

[0033] As shown in Figure 2 , the guide device includes a guide wheel 6 and a guide column 13, the guide wheel 6 is installed on the top of the guide column 13 and is used to receive and transmit the top tension of the extension rod 4 to the cable, and the effective tensioning and dynamic compensation of the cable are realized through the mooring tensioner; one side of the guide column 13 is connected with the extension rod 4, and the lower part is placed in the deck guide groove 5, which is used to limit the movement direction of the extension rod 4, i.e. the extension rod 4 extends to push the guide column 13 to the designated position.

[0034] As shown in Figure 2As shown, the guide wheel 6 includes a lower guide column and a peripheral guide groove, ensuring that the cable remains stable and is not easily deviated during guidance. The guide wheel 6 guides the cable into the correct path of the mooring tensioner through the peripheral guide groove during the cable launching process, avoiding jamming or damage caused by deviation. The guide wheel 6 works with the telescopic rod 4 of the mooring tensioner to ensure smooth movement of the cable when entering the mooring tensioner and maintain appropriate tension. In addition, the guide wheel 6 also has wear resistance and can operate stably for a long time under high pressure and dynamic load.

[0035] In the present application, the rotating shaft of the guide wheel 6 uses a precision bearing to reduce frictional resistance and ensure flexible rotation; the width and depth of the peripheral guide groove are precisely calculated to facilitate the guidance of the cable while avoiding excessive wear. The guide wheel 6 is equipped with anti-loosening bolts and sealing rings to prevent faults caused by vibration or water vapor intrusion.

[0036] The working principle of the mooring tensioner of the present application is to store and release energy by compression and expansion of gas. When the hydraulic pump in the hydraulic system supplies oil to the hydraulic cylinder, the liquid will compress the gas, increasing the pressure inside the energy storage tank 7. The hydraulic cylinder 12 is a device that converts hydraulic energy into mechanical energy, composed of a cylinder body, a telescopic rod, a sealing element, etc. When the liquid flows from the energy storage tank 7 into the hydraulic cylinder 12, the liquid pressure is used to drive the telescopic rod 4 to move, thereby realizing the work of the hydraulic cylinder. After the bow and stern cables of the two ships are connected, the energy storage tank 7 is pressurized to the preset value, and the gas pressure in the tank pushes the liquid out through the pipe flow circuit, driving the hydraulic cylinder to fully extend the telescopic rod 4.

[0037] Based on the alongside berthing dynamic compensation system, the present application provides a double-ship parallel berthing method, and the flow chart is as shown in Figure 4 S1, the fracturing ship is fixed in the working position by the main ship anchoring system; S2, the sand-carrying ship approaches the side of the fracturing ship and maintains a safe distance; S3, the sand-carrying ship is connected to the main ship by mooring and realizes berthing based on the alongside berthing dynamic compensation system.

[0038] S4, separation and finishing after the work is completed.

[0039] Each step will be described in detail as follows: S1: The fracturing ship is stably berthed in the designated sea area ​According to the dynamic positioning capability of the fracturing ship 1 or the water depth and seabed topography characteristics of the operation sea area, the appropriate anchor point position is selected, and the fracturing ship is parked in the designated area through anchoring and mooring or dynamic positioning system. If the anchoring and mooring system is selected, the appropriate anchor point is selected according to the sea conditions, and the position of the fracturing ship is fixed through mooring; if the dynamic positioning system is selected, the dynamic positioning module of the fracturing ship needs to be started, and the related sensors (such as compass, GPS, depth finder, etc.) need to be ensured to work normally to maintain the stable position of the fracturing ship. After the parking of the fracturing ship is completed, the stability of the whole system needs to be tested, including the stress analysis of the anchor point, the tension monitoring of the mooring line and the running state check of the dynamic positioning module. According to the water depth and flow rate of the operation sea area, the length of the mooring line is adjusted through manual or automatic control system to ensure that the fracturing ship remains stable in the designated area. After the parking of the fracturing ship is completed, the system stability test needs to be carried out, including: checking whether the anchor point is firm or the feedback accuracy of the dynamic positioning system; monitoring the displacement of the fracturing ship under external interference (such as wind and wave). S2: Navigation and approach of sand-carrying ship to fracturing ship The sand-carrying ship 2 plans the path through navigation control, GPS and compass, and travels in the direction of the fracturing ship according to the predetermined route. During this process, the system will monitor the sailing posture of the sand-carrying ship in real time and make adjustments. The sand-carrying ship 2 gradually approaches the fracturing ship 1 according to the preset route, and needs to pay attention to control the speed to avoid deviation from the channel or collision due to too high speed. When the sand-carrying ship 2 approaches the fracturing ship 1, the speed reduction mechanism needs to be started to reduce the relative speed of the sand-carrying ship, so as to ensure the safety of the berthing process. After the sand-carrying ship arrives at the predetermined position, the system will calibrate the distance, angle and other parameters between the two ships.

[0040] S3: Parallel berthing of two ships based on berthing mooring dynamic compensation system Firstly, the preliminary mooring connection is made. After the sand-carrying ship reaches the designated position, the fracturing ship throws the mooring line and connects the mooring line 11 to the mooring bitt 3 of the sand-carrying ship. The bow or stern line is fixed to the corresponding position of the fracturing ship by manual or automatic operation. At this time, the sand-carrying ship 2 and the fracturing ship 1 are only preliminarily connected and not completely stable. After completing the preliminary mooring connection, the safety of the entire system needs to be comprehensively checked, including whether the distance between the two ships meets the safety requirements, the force condition of the mooring line, the installation state of the fender assembly 9, and the preparation work of the dynamic compensation system. Then the initial adjustment function of the dynamic compensation system is started, the mooring line tensioner is started, the accumulator tank 7 is pressed to the preset value, the extension rods 4 of the mooring line tensioner are fully extended, the guide column is pushed to slide in the guide groove 5, the guide wheel 6 is connected above the guide column 13, the appropriate initial tension of the mooring line is applied through the air energy storage and hydraulic transmission technology, the mooring line is guided to the guide wheel 6 of the mooring line tensioner, and the automatic mooring machine 8 tightens the ropes to the preset safety value. After the sand-carrying ship is tightly attached to the fender of the fracturing ship, the double-ship berthing is completed. At this time, the tensioner automatically adjusts the mooring line tension according to the current sea conditions to maintain the stability of the double-ship position and ensure that the tension fluctuation is small during the dynamic compensation process. If the relative displacement between the two ships is detected to be out of the safe range, the mooring line tension is increased or decreased by the mooring line tensioner to eliminate the deviation; if the fender bears a larger impact load, the pre-tightening force needs to be appropriately reduced to avoid damage.

[0041] S4: separation and finishing after completing the work After completing the double-ship berthing work, the mooring connection needs to be gradually released, and the safe distance between the two ships needs to be ensured. The fender is removed from the contact part of the fracturing ship and the sand-carrying ship, and necessary cleaning and maintenance are performed. All modules of the dynamic compensation system are closed, and the initial state is restored, ready for the next operation.

Claims

1. A dynamic mooring system for a ship-to-ship docking, comprising: a fender assembly arranged on the side of a main ship or a secondary ship, and composed of a hollow barrel-shaped elastic rubber; a mooring line set including a bowline, a stern line and a center line; a mooring line tensioner connected to the end of the mooring line set, and used for dynamically adjusting the tension of the mooring line.

2. The dynamic mooring system of claim 1, wherein: The mooring line tensioner comprises: an accumulator tank configured to maintain the tension change range within a preset range during the working stroke by using an air-accumulation hydraulic transmission structure; a hydraulic cylinder in fluid communication with the accumulator tank, and a telescopic rod reciprocating under the drive of the hydraulic cylinder; a guide device for transmitting the top tension of the telescopic rod to the mooring line.

3. The dynamic mooring system of claim 2, wherein: The guide device comprises a guide wheel and a guide column; the guide wheel is mounted on the top of the guide column, and used for receiving and transmitting the top tension of the telescopic rod to the mooring line; one side of the guide column is connected to the telescopic rod, and the lower part is arranged in a deck guide slot, and used for limiting the movement direction of the telescopic rod.

4. The dynamic mooring system of claim 3, wherein: The guide wheel comprises a lower guide column and a peripheral guide groove.

5. The dynamic mooring system of claim 4, wherein: The mooring line tensioner comprises an automatic mooring machine, which is used for tightening the mooring line to a preset safe tension value. 6.A sea-based double-ship parallel docking system, comprising: a main ship anchoring system configured to fix the position of the main ship by an anchoring system or a dynamic positioning system; a secondary ship mooring system comprising the dynamic mooring system for a ship-to-ship docking according to any one of claims 1-5, and connecting the secondary ship to the main ship by a mooring line. 7.A sea-based double-ship parallel docking method using the sea-based double-ship parallel docking system according to claim 6, comprising the following steps: S1, fixing the main ship to a working position by the main ship anchoring system; S2, approaching the secondary ship to the side of the main ship and keeping a safe distance; S3, connecting the secondary ship to the main ship by a mooring line, and realizing docking based on the dynamic mooring system for a ship-to-ship docking.

8. A method of docking two vessels side by side at sea according to claim 7, characterized in that: In step S3, the docking step using the dynamic mooring system for a ship-to-ship docking is as follows: 1) starting the mooring line tensioner, pressurizing the accumulator tank to a preset pressure value, and fully extending the telescopic rod; 2) introducing each mooring line into the corresponding guide wheel, and tightening the mooring line to a preset safe tension value; 3) synchronously adjusting the tension of each mooring line, so that the secondary ship is tightly attached to the fender assembly of the main ship.

9. A method of docking two vessels side by side at sea according to claim 8, characterized in that: After step 3), the following steps are further included: real-time monitoring of the environmental load and the relative displacement of the ship, and dynamically adjusting the nitrogen pre-charge pressure of the accumulator tank to be generally 60%-80% of the system working pressure, the system working pressure being 20 MPa, and the pre-charge pressure being 12-16 MPa.

10. A method of docking two vessels side by side at sea according to claim 8 or 9, characterized in that: The main ship is a fracturing ship, and the secondary ship is a sand-carrying ship, and the method is used for realizing continuous sand-carrying operation between the fracturing ship and the sand-carrying ship during offshore fracturing operation.

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