A deep-sea submarine cable synchronous laying construction method

Abstract

The application discloses a deep-sea submarine cable synchronous laying and burying construction method, which comprises the following steps: firstly, a main construction ship completes equipment testing and route pre-investigation in a work area, and then, the first end of the submarine cable is lowered and a platform is pulled; in a normal cable laying stage, the layback is controlled to be 10-20 m; after reaching a ditch starting point, an anchor chain counterweight is bound in front of a burying plough, the burying plough is hoisted to the seabed, the layback is increased to 50-60 m and the rope tension is kept; after starting the burying plough water pump to form a slope, the laying and burying operation is carried out; an ROV carries a positioning beacon and is arranged in the middle section of a submarine cable catenary, the layback is calculated by using a catenary formula and the submarine cable touchdown point is inverted; after reaching the end platform, the burying plough is recovered, the end cable laying and platform pulling are completed. The application can prevent the burying plough from being tilted and overturned underwater, solves the monitoring difficulty of low visibility of the deep-sea submarine cable touchdown point, realizes synchronous laying and burying operation, and improves the deep-sea submarine cable construction efficiency.

Description

Technical Field

[0001] This invention belongs to the field of marine oil engineering technology, and in particular relates to a method for synchronous laying of deep-sea submarine cables. Background Technology

[0002] Existing shallow-water cable laying and burial techniques have significant limitations in deep-water adaptability, making it difficult to meet the needs of submarine cable construction in waters up to 100 meters deep. On one hand, the hydrological environment in deep-water areas is complex, with vastly different current disturbances, seawater pressure, and seabed geological conditions compared to shallow waters, placing higher demands on the pressure-bearing capacity and operational stability of trenching and cable-laying equipment. On the other hand, existing construction methods heavily rely on the precise synchronization of the towing speed of the construction vessel, the efficiency of the trenching plow, and the cable-laying speed; the precision of equipment coordination and the matching degree of operational timing directly determine construction efficiency and quality.

[0003] In deep-water construction scenarios, the problems of insufficient equipment adaptability and difficulty in synchronous control of multiple equipment operations in existing shallow-water construction processes are further amplified. This easily leads to misalignment of trenching and cable laying operations, resulting in poor trench formation quality, cable misalignment, and failure to meet burial depth standards. This not only significantly reduces the overall efficiency of cable laying operations but also increases the probability of rework, significantly increasing costs in multiple dimensions such as vessel on-site presence, equipment maintenance, and manual construction. This seriously restricts the efficient and economical construction of submarine cable projects in deep-water areas.

[0004] Therefore, there is an urgent need to design a method for synchronous laying of deep-sea cables to solve the problems mentioned above. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synchronous laying of deep-sea submarine cables, which has the advantages of improving the efficiency of submarine cable laying operations, greatly saving construction costs, and solving the problems involved in the background art.

[0006] To achieve the above objectives, the specific technical solution of the deep-sea submarine cable synchronous laying construction method of the present invention is as follows: A method for synchronous laying of deep-sea submarine cables includes the following steps: S1. The main construction vessel arrives at the construction site and completes equipment testing, conducts route pre-survey, and confirms that there are no obstacles on the submarine cable laying route. S2. Initialize the submarine cable head end, and use the stern crane to lower the submarine cable head end to complete the submarine cable head end platform pulling operation. S3. During the normal laying phase of the submarine cable, adjust the position of the main construction vessel and control the Layback value to be maintained at 10-20m. S4. When the main construction vessel arrives at the trenching starting point, a section of anchor chain is fixed to the front end of the burying plow with a sling, and the burying plow is lifted out of the ship's side. S5. Monitor the attitude of the burying plow and the tension of the main traction rope in real time through the monitoring instrument, and dynamically adjust the angle between the burying plow and the seabed surface and the cable laying speed. S6. Lower the burying plow smoothly to the seabed, move the main construction vessel, increase the layback between the burying plow and the stern to 50-60m, and maintain the tension of the main traction rope and the lifting wire rope. S7. Start the water pump for burying the burial plow. After the slope is built, carry out the work of laying and burying the submarine cable at the same time. S8. During the operation, the ROV is positioned in the middle of the catenary of the submarine cable and the layback distance is calculated according to the catenary formula to ensure the safety of the submarine cable laying. Layback is the horizontal distance from the cable exit point to any point on the cable body, S is the catenary length of the cable in the water, and h is the water depth. The formula is as follows: S9. When the construction reaches the end platform position, the burying plow will be retrieved to the deck of the main construction vessel to carry out the submarine cable end laying operation. After the submarine cable end platform is pulled out, the submarine cable laying construction will be completed.

[0007] Furthermore, in S1, the route pre-survey is used to identify underwater obstacles within the laying route area, providing basic data for the submarine cable laying path and avoiding the risk of construction collisions.

[0008] Furthermore, in S2, the initialization operation of the submarine cable head includes submarine cable head inspection and head protection treatment to ensure the integrity of the submarine cable structure during the lowering of the submarine cable head and the platform pulling operation.

[0009] Furthermore, in S3, Layback is the horizontal distance from the cable outlet to any point on the cable body. This parameter is controlled by adjusting the ship's position to maintain the stability of the cable catenary shape during the normal cable laying phase.

[0010] Furthermore, in S4, an anchor chain is tied to the front end of the burial plow to increase the counterweight of the front section of the burial plow and prevent the burial plow from tilting or overturning underwater in water depths of up to 100 meters.

[0011] Furthermore, in S5, the monitoring device collects data on the attitude of the burial plow and the tension of the main traction rope, and adjusts the burial plow's tilt angle and cable release speed in real time based on the collected data to adapt to underwater construction conditions.

[0012] Furthermore, in S6, the layback of the shifting vessel is increased to 50-60m, and the tension of the main traction rope and lifting wire rope is maintained to ensure that the burying plow sits stably on the bottom, providing a working foundation for subsequent trenching and cable laying.

[0013] Furthermore, in S7, the installation of the plow pump enables the creation of a slope on the seabed, and the cable reel and tensioner are synchronized with the trenching speed to release the submarine cable, achieving simultaneous trenching, cable laying, and cable burial operations.

[0014] Furthermore, in the S8, the ROV is equipped with a positioning beacon and positioned in a highly visible location in the middle section of the catenary to monitor the status of the submarine cable.

[0015] Furthermore, in S9, after the burial plow is recovered, no trenching work is carried out. Only the end of the submarine cable is laid and the platform is pulled out to complete the laying and burial of the entire submarine cable.

[0016] The method for synchronous laying of deep-sea submarine cables of the present invention has the following advantages: pass. Attached Figure Description

[0017] Figure 1 This is a construction schematic diagram of the synchronous laying method for deep-sea submarine cables according to the present invention; Figure 2 This is a schematic diagram of the anchor chain configuration for the synchronous laying and burial method of deep-sea submarine cables according to the present invention; Figure 3 This is a schematic diagram of the laying plow being lowered in the synchronous laying method for deep-sea submarine cables according to the present invention. Figure 4 This is a schematic diagram of the placement of the burial plow in the synchronous laying method for deep-sea submarine cables according to the present invention.

[0018] Explanation of markings in the diagram: 1. Main construction vessel; 2. Stern crane; 3. Laying plow; 4. Lifting wire rope; 5. Main traction rope; 6. Submarine cable; 7. Anchor chain; 8. ROV. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0021] The following is a reference to the appendix. Figure 1 To be continued Figure 4 This invention describes a method for synchronously laying and burying deep-sea submarine cables.

[0022] like Figure 1As shown, the deep-sea cable synchronous laying construction method of the present invention mainly includes the following steps: S1. After the main construction vessel 1 arrives at the work area and completes the test, a route pre-survey will be conducted to ensure that there are no obstacles to the route laying. The main construction vessel 1 sailed to the target construction area in waters with a depth of 100 meters and anchored or used dynamic positioning to fix its position. The ship's navigation system, cable tensioner, cable reel, stern crane 2, burying plow 3, and its associated monitoring equipment, ROV8, and positioning beacon system were then powered on, integrated, and tested for performance to confirm that all equipment had normal communication and operational functions. A multibeam echo sounder and side-scan sonar were then activated to conduct a route pre-survey, continuously scanning along the designed cable route to collect information on seabed topography, reefs, old pipelines, subsidence pits, and other obstacles. Identified risk points were reviewed, and a route survey report was generated to confirm that the entire laying route met construction conditions and to avoid the risk of subsequent cable 6 and burying plow 3 encountering obstacles.

[0023] S2, Initialization of the bow end of submarine cable 6, with the assistance of stern crane 2 to lower the bow end and pull out the bow end platform; After the route pre-survey and acceptance were passed, the initialization work of the head end of submarine cable 6 was carried out. The operators conducted an integrity inspection of the appearance, armor layer, and insulation layer of the head end of submarine cable 6, and performed sealing and protective treatment on the end to prevent seawater erosion and damage to the cable body. Using the stern crane 2 and cable clamping fixtures, the head end of submarine cable 6 was clamped and slowly lowered into the water from the cable outlet at the stern. The head end of submarine cable 6 was pulled to the head end platform by the above-water / underwater traction device. On the platform, the head end of submarine cable 6 was fixed, passed through the cabin, and pulled into place, completing the head end anchoring and establishing the starting point for subsequent continuous cable laying.

[0024] S3. During normal laying, adjust the vessel position to keep the layback at 10~20m; After the initial platform pull-out operation is completed, the main construction vessel 1 moves forward at low speed along the route to enter the pre-laying stage of submarine cable 6. The vessel's lateral and longitudinal positions are adjusted in real time through the dynamic positioning system, and the release speed of submarine cable 6 is controlled in conjunction with the stern tensioner. The monitoring data of the cable 6 exit point position is read in real time to control the layback, that is, to keep the horizontal distance from the cable 6 exit point to the corresponding point on the cable body stable in the range of 10-20m, maintain the smooth underwater catenary shape of submarine cable 6, avoid excessive tension or slack of the cable body, and ensure that the stress on submarine cable 6 is within a safe range during the pre-laying stage.

[0025] S4. When the trenching start point is reached, use a sling to tie and fix a section of anchor chain 7 to the front end of the buried plow 3, and lift the buried plow 3 out of the ship's side. The main construction vessel 1 sails to the pre-designated trenching starting point and then stops. High-strength slings are used to secure a counterweight anchor chain 7 to the front end of the plow head of the burial plow 3. The weight of the anchor chain 7 is pre-calculated based on the construction water depth, the self-weight of the burial plow 3, and the seabed soil conditions. This chain is used to increase the counterweight at the front of the burial plow 3, addressing the problem of excessive buoyancy at the front end of the burial plow 3 in water depths of 100 meters, which could easily cause it to tilt or capsize. After the slings are secured and their connection is checked, the stern crane 2 is started to smoothly lift the burial plow 3, move it off the ship's side, and suspend it above the water surface outside the ship, ready for lowering.

[0026] S5. Monitor the attitude of the burying plow 3 and the tension of the main traction rope 5 through the monitoring instrument, and dynamically adjust the angle between the burying plow 3 and the seabed surface and the cable laying speed. After the burying plow 3 is hoisted out of the ship's side, the ship's monitoring instrument collects data in real time from the built-in tilt sensor, attitude sensor, and tension sensor of the main traction rope 5. It simultaneously displays the pitch and roll attitude of the burying plow 3 and the real-time tension value of the main traction rope 5. Based on the monitoring data, the operators dynamically adjust the length of the main traction rope 5 and the lifting wire rope 4, adjusting the angle between the burying plow 3 and the seabed surface. Simultaneously, they coordinate with the stern cable reel and tensioner to match the lowering and towing conditions of the burying plow 3, adjusting the cable laying speed of the submarine cable 6 in real time to prevent over-tensioning or cable stacking.

[0027] S6. After the burying plow 3 is smoothly lowered to the seabed, move the ship and increase the distance between the burying plow 3 and the stern to about 50-60m, while maintaining the tension of the main traction rope 5 and the lifting wire rope 4. After monitoring the attitude of the burial plow 3 and confirming that there were no abnormalities, the stern crane 2 slowly lowered the burial plow 3, allowing the plow blades to sit steadily on the seabed and confirming that the plow body had touched the bottom. The main construction vessel 1 slowly moved forward along the laying route, gradually increasing the horizontal distance between the stern and the burial plow 3, adjusting the layback of this section to the range of 50-60m. During the operation, the winch was continuously controlled to maintain a constant tension on the main traction rope 5 and the lifting wire rope 4, ensuring that the burial plow 3 was stably attached to the seabed, preventing the plow body from floating or shifting, and providing a stable foundation for the trenching operation.

[0028] S7. Start the water pump for laying the burial plow 3. After the slope is completed, begin the laying and burial of submarine cable 6. After the burying plow 3 is firmly planted and its layback parameters are stable and meet the standards, the high-pressure water pump on the burying plow 3 is activated. The high-pressure water jet disturbs the seabed soil, creating a working slope in front of the plow blade, thus completing the seabed slope creation. The completion of slope creation is determined by the monitoring instrument's feedback on the seabed soil disturbance state and the plow's penetration depth reaching the design value. Subsequently, the main construction vessel 1 moves forward at a constant speed, towing the burying plow 3. The cable reel, tensioner, and burying plow 3 release the submarine cable 6 synchronously. The submarine cable 6 falls into the excavated trench as the plow moves, realizing simultaneous trenching, cable laying, and burying operations, and carrying out continuous operation of laying and burying cables simultaneously.

[0029] S8. During operation, the ROV8 is positioned in the middle of the catenary, and the Layback distance is derived according to the formula to ensure laying safety. During the ongoing laying and burying operation, the excavation of trenches by the burying plow 3 generated a large amount of underwater mud, obscuring the contact point of the submarine cable 6 and making direct observation impossible. An ROV8 equipped with a positioning beacon was deployed to a location with high visibility in the middle section of the catenary of the submarine cable 6. The ROV8 collected the cable coordinates at that location in real time; the water depth h and the total length S of the underwater catenary of the submarine cable 6 were also collected and substituted into the catenary formula: The horizontal layback distance was calculated, and the actual mud contact point of submarine cable 6 was deduced through inversion. Based on the calculation results, the ship's position and cable laying speed were dynamically adjusted to ensure the safety of the cable chain under stress and to avoid the risk of excessive stretching and bending of the cable.

[0030] S9. Upon reaching the terminal platform, retrieve the buried plow 3 to the ship deck, carry out the terminal laying, complete the terminal platform pull-out, and the submarine cable laying is completed. When the main construction vessel 1 reaches the pre-set position near the end platform, it stops towing the laying plow 3. The hoisting wire rope 4 and main traction rope 5 are operated by winches to slowly lift the laying plow 3 from the seabed and out of the water. The stern crane 2 then lifts the laying plow 3 back and secures it to the deck of the main construction vessel 1, completing the trenching and cable laying process. The vessel continues to move at low speed to lay the end of the submarine cable 6, controlling the catenary state of the cable 6. The end of the cable 6 is then pulled to the end platform, completing the platform pull-out and end-fixing operations. After the anchoring of the cable 6 at both the bow and end platforms is inspected and approved, the entire submarine cable laying construction is completed.

[0031] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for synchronous laying and burying of deep-sea submarine cables, characterized in that, Includes the following steps: S1. The main construction vessel arrives at the construction site and completes equipment testing, conducts route pre-survey, and confirms that there are no obstacles on the submarine cable laying route. S2. Initialize the submarine cable head end, and use the stern crane to lower the submarine cable head end to complete the submarine cable head end platform pulling operation. S3. During the normal laying phase of the submarine cable, adjust the position of the main construction vessel and control the Layback value to be maintained at 10-20m. S4. When the main construction vessel arrives at the trenching starting point, a section of anchor chain is fixed to the front end of the burying plow with a sling, and the burying plow is lifted out of the ship's side. S5. Monitor the attitude of the burying plow and the tension of the main traction rope in real time through the monitoring instrument, and dynamically adjust the angle between the burying plow and the seabed surface and the cable laying speed. S6. Lower the burying plow smoothly to the seabed, move the main construction vessel, increase the layback between the burying plow and the stern to 50-60m, and maintain the tension of the main traction rope and the lifting wire rope. S7. Start the water pump of the burying plow, and after the slope is completed, carry out the submarine cable laying and burying operation. S8. During the operation, the ROV is positioned in the middle of the catenary of the submarine cable and the layback distance is calculated according to the catenary formula to ensure the safety of the submarine cable laying. Layback is the horizontal distance from the cable exit point to any point on the cable body, S is the catenary length of the cable in the water, and h is the water depth. The formula is as follows: S9. When the construction reaches the end platform position, the burying plow will be retrieved to the deck of the main construction vessel to carry out the submarine cable end laying operation. After the submarine cable end platform is pulled out, the submarine cable laying construction will be completed.

2. The method for synchronous laying of deep-sea submarine cables according to claim 1, characterized in that, In S1, the route pre-survey is used to identify underwater obstacles within the laying route area, providing basic data for the submarine cable laying path and avoiding the risk of construction collisions.

3. The method for synchronous laying of deep-sea submarine cables according to claim 1, characterized in that, In S2, the initialization work at the head of the submarine cable includes inspection of the cable head and protection treatment of the head, to ensure the integrity of the cable structure during the lowering of the cable head and the platform pulling operation.

4. The method for synchronous laying of deep-sea submarine cables according to claim 1, characterized in that, In S3, Layback is the horizontal distance from the cable outlet to any point on the cable body. This parameter is controlled by adjusting the ship's position to maintain the stability of the cable catenary shape during the normal cable laying phase.

5. The method for synchronous laying of deep-sea submarine cables according to claim 1, characterized in that, In S4, a fixed anchor chain is tied to the front end of the burial plow to increase the counterweight of the front section of the burial plow and prevent the burial plow from tilting or overturning underwater in water depths of up to 100 meters.

6. The method for synchronous laying of deep-sea submarine cables according to claim 1, characterized in that, In S5, the monitoring device collects data on the attitude of the burial plow and the tension of the main traction rope. Based on the collected data, it adjusts the tilt angle of the burial plow and the cable release speed in real time to adapt to underwater construction conditions.

7. The method for synchronous laying of deep-sea submarine cables according to claim 1, characterized in that, In S6, the layback of the shifting vessel is increased to 50-60m. In conjunction with maintaining the tension of the main traction rope and lifting wire rope, the burying plow is ensured to sit stably on the bottom, providing a working foundation for subsequent trenching and cable laying.

8. The method for synchronous laying of deep-sea submarine cables according to claim 1, characterized in that, In S7, the installation of the plow pump enables the creation of a slope on the seabed, and the cable reel and tensioner are synchronized with the trenching speed to release the submarine cable, achieving simultaneous trenching, cable laying, and cable burial operations.

9. The method for synchronous laying of deep-sea submarine cables according to claim 1, characterized in that, In the S8, the ROV carries a positioning beacon and is positioned in a highly visible location in the middle section of the catenary to monitor the status of the submarine cable.

10. The method for synchronous laying of deep-sea submarine cables according to claim 1, characterized in that, In S9, after the burying plow is recovered, no trenching work is carried out. Only the end of the submarine cable is laid and the platform is pulled out to complete the laying and burial of the entire submarine cable.

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