A method and device for pulling piles from bottom of self-elevating platform

Abstract

The present invention relates to the technical field of pile extraction of a self-elevating platform, and provides a method and device for extracting piles from a bottom of a self-elevating platform, comprising the following steps: lowering a hull into water by means of a lifting assembly; starting a ballast assembly, and injecting ballast water into a ballast tank by means of a ballast pump, so that the buoyancy of the platform hull is balanced with the weight of the hull; using the lifting assembly to drive the hull to continue to move downward until the bottom plate of the hull contacts the seabed foundation; starting a third nozzle for spraying and flushing, and keeping the lifting assembly in a state of lowering the platform until the pile legs are loosened; after continuing to use the lifting assembly to pull the pile boots out of the mud, the pile extraction is stopped; starting a first nozzle for spraying and flushing, and at the same time using a ballast pump to discharge the ballast water in the ballast tank until the bottom of the hull is loosened, and the hull drives the pile legs and the pile boots to float up, and the pile extraction process is completed. The present invention solves the problem that the self-elevating platform is not applicable in shallow water, and improves the applicability of the self-elevating platform by using the seabed foundation to provide a reaction force.

Description

Technical Field

[0001] The invention relates to the technical field of pile extraction of a self-elevating platform, and in particular to a method and a device for extracting piles from a bottom-seated self-elevating platform. Background Art

[0002] As the development of large offshore oilfields enters a slowdown period, development attention is gradually turning to marginal oilfields. According to data, marginal oilfields account for more than 50% of my country's marine oil and gas reserves. Self-elevating platforms have unique advantages in the development of marginal oilfields due to their wide range of applications, reusability, good economy, and low environmental impact. When pulling piles on a self-elevating platform, the main hull of the platform is generally lowered into the water using a lifting assembly, and the piles are pulled out by relying on the buoyancy of the seawater on the hull. However, if the water depth in the sea area where the platform is located is extremely shallow, that is, the water depth is less than the designed draft depth of the platform for pulling piles, even if the main hull of the platform touches the seabed, the buoyancy of the main hull of the platform is still less than the resistance to pulling piles. At this time, it is impossible to pull piles by relying on the buoyancy of the platform, which greatly limits the application of self-elevating platforms in shallow waters. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention provides a method and device for pulling piles from a bottom of a self-elevating platform, so as to improve the applicability of the self-elevating platform.

[0004] The present invention provides a method for pulling piles from a self-elevating platform, comprising the following steps:

[0005] Lowering the hull into the water via the lifting assembly;

[0006] Start the ballast assembly and use the ballast pump to inject ballast water into the ballast tank so that the buoyancy of the platform hull is balanced with the weight of the hull;

[0007] The lifting assembly is used to drive the hull to continue to move downward until the bottom plate of the hull contacts the seabed foundation;

[0008] Open the third nozzle to spray and flush, and keep the lifting assembly in the state of lowering the platform until the pile legs loosen and start to move upward;

[0009] Continue to use the lifting assembly to pull the pile shoe out of the mud, then stop pulling the pile;

[0010] Open the first nozzle for spraying, and use the ballast pump to discharge the ballast water in the ballast tank until the bottom of the hull is loosened, and the hull drives the pile legs and pile shoes to float, completing the pile pulling process.

[0011] According to a method for pulling piles from a self-elevating platform provided by the present invention, during the pulling-up period of the pile shoe, the method further comprises the following steps: opening the second nozzle for spraying to flush the mud in the mud guide groove.

[0012] According to a method for bottom seating and pile extraction of a self-elevating platform provided by the present invention, the following steps are also included before the hull is lowered: the seabed is processed to make it flat to protect the bottom plate of the hull.

[0013] The present invention also provides a self-elevating platform bottom-seating and pile-pulling device, comprising: a hull, pile legs, pile shoes, a ballast assembly, a lifting assembly, a load-discharging assembly, a first nozzle and a third nozzle, wherein the pile legs comprise an upper portion of the pile legs inserted into the seawater and a lower portion of the pile legs inserted into the mud; the pile shoes are fixed to the lower portion of the pile legs; the third nozzle is arranged on the outer side wall of the pile shoes; the ballast assembly comprises a ballast tank and a ballast pump, the ballast pump and the ballast tank are arranged inside the hull, and the ballast pump is suitable for injecting or discharging ballast water into the ballast tank; the lifting assembly comprises a lifting The upper section of the lifting assembly and the lower section of the lifting assembly, the upper section of the lifting assembly is connected with the upper section of the pile leg by a pin, the lower section of the lifting assembly is fixedly connected with the hull, and the upper section of the lifting assembly is slidably connected with the lower section of the lifting assembly; the first nozzle is arranged on the outer side walls of the bottom plate and the side plate of the hull, the hull includes a mud guide groove, the mud guide groove is arranged on the bottom plate of the hull, and the mud guide groove is arranged around the pile leg; the inner side wall of the mud guide groove is inclined in the direction away from the hull to form a guide surface, and the second nozzle is arranged on the inner side wall of the mud guide groove.

[0014] According to the self-elevating platform bottom seating and pile pulling device provided by the present invention, a watertight double bottom is arranged inside the hull.

[0015] According to the self-elevating platform bottom-seating and pile-pulling device provided by the present invention, the size of the mud guide groove is larger than the size of the pile shoe.

[0016] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0017] The method and device for pulling piles from the bottom of a self-elevating platform according to the embodiments of the present invention utilizes the seabed foundation to provide a reaction force to the hull and combines the lifting components to achieve pile pulling, thereby solving the problem of pulling piles when the self-elevating platform is operating in extremely shallow waters, thereby improving the applicability of the self-elevating platform.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The present invention is a flowchart of a method for bottom seating and pile extraction of a self-elevating platform.

[0021] Figure 2 It is a structural schematic diagram of the bottom seating and pile pulling device of the self-elevating platform provided by the present invention.

[0022] Figure 3 It is a partial structural schematic diagram of the bottom seating and pile pulling device of the self-elevating platform provided by the present invention.

[0023] Reference numerals:

[0024] 1. Hull; 2. Pile legs; 3. Pile shoes; 4. Ballast assembly; 5. Lifting assembly; 6. First nozzle; 7. Mud guide trough; 8. Second nozzle; 9. Third nozzle; 10. Jet power assembly. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0026] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships 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 devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0027] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0028] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0029] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0030] In the related technology, the self-elevating platform cannot work normally in shallow water. In order to improve the application scope of the self-elevating platform, after the hull is matched with the soil on the seabed by using the lifting system, the pile shoe can be pulled out of the soil, and then the first nozzle and the ballast system can be used to separate the hull and the soil, and finally the self-elevating platform can perform pile pulling operations in shallow water, thereby expanding the application scope of the self-elevating platform.

[0031] Figure 1 The present invention is a flowchart of a method for bottom seating and pile extraction of a self-elevating platform.

[0032] The present invention also provides a method for pulling piles from a self-elevating platform. Figure 1 As shown, the method for pulling piles from the bottom of a self-elevating platform includes steps S1 to S6:

[0033] S1: lowering the hull 1 into the water through the lifting assembly 5;

[0034] S2: starting the ballast assembly 4, and continuously injecting ballast water into the ballast tank through the ballast pump, so that the buoyancy of the platform hull 1 is basically balanced with the weight of the hull 1;

[0035] S3: the lifting assembly 5 drives the hull 1 to continue to move downward until the bottom plate of the hull 1 contacts the seabed foundation;

[0036] S4: The third nozzle 9 is turned on for spraying, and the lifting assembly 5 continues to exert a downward force on the hull 1 until the pile leg 2 starts to move upward;

[0037] S5: reducing the downward force of the lifting assembly 5, and the pile leg 2 continues to move upward until the pile shoe 3 is pulled out of the mud, and then the pile pulling is stopped;

[0038] S6: Open the first nozzle 6 for spraying, open the ballast assembly to discharge the ballast water from the ballast tank until the bottom of the hull 1 is loosened, and the hull 1 drives the pile legs 2 and the pile shoes 3 to float, completing the pile pulling process.

[0039] According to a method for pulling piles from a self-elevating platform provided by the present invention, during the pulling up of the pile shoe 3 , the second nozzle 8 is turned on for spraying to flush the mud in the mud guide groove 7 .

[0040] According to a method for bottom seating and pile extraction of a self-elevating platform provided by the present invention, before the hull 1 is lowered, the seabed is processed to make it flat, so as to protect the bottom plate of the hull 1.

[0041] According to a method for bottom seating and pile extraction of a self-elevating platform provided by the present invention, in addition to meeting conventional design requirements, the hull 1 structure should also adopt the design requirements of the classification specifications for the platform sinker, and the hull should be structurally designed and analyzed in the bottom seating and pile extraction state. The bottom plate pressure head is selected according to "maximum lifting force of the lifting component + water depth", and the force-bearing area is considered to be 80% of the area of ​​the hull bottom plate.

[0042] Figure 2 It is a structural schematic diagram of the bottom seating and pile pulling device of the self-elevating platform provided by the present invention. Figure 3 It is a partial structural schematic diagram of the bottom seating and pile pulling device of the self-elevating platform provided by the present invention.

[0043] The present invention provides a self-elevating platform bottom-seating pile-pulling device, such as Figures 2 to 3As shown, the bottom-seating and pile-pulling device of the self-elevating platform includes: a hull 1, pile legs 2, pile shoes 3, a ballast assembly 4, a lifting assembly 5, a load-discharging assembly, a first nozzle 6 and a third nozzle 9. The pile legs 2 include an upper leg section inserted into the seawater and a lower leg section inserted into the mud, the pile shoes 3 are fixed to the lower leg section, and the third nozzle 9 is arranged on the outer side wall of the pile shoes 3; the ballast assembly 4 includes a ballast tank and a ballast pump, the ballast pump and the ballast tank are arranged inside the hull 1, and the ballast pump is suitable for injecting or discharging ballast water into the ballast tank; the lifting assembly 5 includes an upper lifting assembly section and a lower lifting assembly section, and the upper lifting assembly section is connected to the upper leg section section by a latch, The lower section of the lifting assembly is fixedly connected to the hull 1, and the upper section of the lifting assembly is slidably connected to the lower section of the lifting assembly; the first nozzle 6 is arranged on the outer walls of the bottom plate and the side plates of the hull 1, and the hull 1 includes a mud guide groove 7, which is arranged on the bottom plate of the hull 1, and the mud guide groove 7 is arranged around the pile leg 2, and the inner wall of the mud guide groove 7 is inclined in the direction away from the hull 1 to form a guide surface, and a second nozzle 8 is arranged on the inner wall of the mud guide groove 7 to facilitate cleaning of the pile shoe 3.

[0044] In this embodiment, by setting up the first nozzle 6, the problem of the self-elevating platform being connected to the soil on the seabed and difficult to separate after it is seated is solved, and the first nozzle 6 is used to spray the soil on the hull 1, thereby reducing the soil adsorption force, and then the buoyancy of the hull 1 is used to drive the pile legs 2 to move upward.

[0045] According to some embodiments of the present invention, the lifting assembly 5 drives the hull 1 to move downward along the pile legs 2. After the hull 1 contacts the sea surface, the hull 1 is subjected to buoyancy. By using a ballast pump to inject ballast water into the ballast tank, the gravity of the hull 1 is equal to the buoyancy of the hull 1. After the hull 1 continues to descend and contacts the seabed, the lifting assembly 5 continues to apply a downward force to the hull 1, and the seabed provides an upward reaction force to the hull 1, which is transmitted to the pile legs 2 through the lifting assembly 5 to achieve pile pulling. After the pile shoes 3 are out of the mud, the lifting assembly 5 stops applying force and releases the ballast water. The hull 1 is driven by the buoyancy to move the pile legs 2 upward to complete the pile pulling.

[0046] According to some preferred embodiments of the present invention, the lifting assembly 5 includes a cylinder body and a plunger rod, the plunger rod is connected to the upper section of the pile leg by a pin, the cylinder body is fixedly connected to the hull 1, the plunger rod and the cylinder body are slidably matched, the cylinder body applies a downward force to the hull 1, and the reaction force of the hull 1 is transmitted to the plunger rod through the cylinder body, acting on the upper section of the pile leg 2, and the pile leg 2 is subjected to an upward force to achieve pile pulling.

[0047] According to some preferred embodiments of the present invention, the lifting force of the lifting assembly 5 is greater than the pile pulling resistance to ensure that the pile leg 2 is pulled out smoothly.

[0048] According to some embodiments of the present invention, the hull 1 also includes a jet power assembly 10, and the jet power assembly 10 includes a first switch and a first connecting pipe. The first switch is connected to the first nozzle 6 through the first connecting pipe, and the first switch is electrically connected to the controller. After the pile shoe 3 is out of the mud, the lifting assembly 5 stops applying downward force, and the hull 1 needs to be separated from the mud. After turning on the first switch, the jet water is sprayed out from the first nozzle 6 through the first connecting pipe to separate the soil around the hull 1 from the hull 1. The first nozzle 6 is arranged on the outer wall of the bottom plate of the hull 1 and on the outer wall of the side plate close to the bottom plate.

[0049] According to the present invention, a self-elevating platform bottom-seating and pile-pulling device is provided. Figures 2 to 3 As shown, a watertight double bottom is provided inside the hull 1 to improve the watertightness of the hull 1 .

[0050] In this embodiment, by providing a watertight double bottom, when encountering an emergency situation where the bottom plate of the ship is damaged and leaking, the watertightness above the second bottom can still be guaranteed, thereby improving the safety of the hull 1, providing sufficient buoyancy for the platform, and ensuring the safety of the platform towing.

[0051] According to the present invention, a self-elevating platform bottom-seating and pile-pulling device is provided. Figures 2 to 3 As shown, the size of the mud guide groove 7 is larger than that of the pile shoe 3 to facilitate the passage of the pile shoe 3.

[0052] According to some embodiments of the present invention, the bottom plate around the pile leg 2 is recessed inward to form a mud guide groove 7. The mud guide groove 7 is larger than the pile shoe 3, has an inclined side wall, and has a second nozzle 8 on the outer surface to facilitate spraying and discharging of mud brought out by the pile shoe 3.

[0053] According to some embodiments of the present invention, the jet power assembly 10 also includes a second switch and a second connecting pipe, the second switch is connected to the second nozzle 8 through the second connecting pipe, the second switch is electrically connected to the controller, after the pile shoe 3 is out of mud, the lifting assembly 5 stops applying downward force, and the mud brought out by the pile shoe 3 passes through the mud guide groove 7. After the second switch is turned on, the jet water is sprayed out from the second nozzle 8 through the second connecting pipe to clean the mud in the mud guide groove 7.

[0054] According to some embodiments of the present invention, the second nozzle 8 starts to spray after the pile shoe 3 produces mud, and the mud brought out by the pile shoe 3 is discharged through the side opening of the mud guide groove 7.

[0055] According to some embodiments of the present invention, a third nozzle 9 is provided to reduce the adsorption force between the pile shoe 3 and the surrounding soil.

[0056] According to some embodiments of the present invention, the jet power assembly 10 also includes a third switch and a third connecting pipe, the third switch is connected to the third nozzle 9 through the third connecting pipe, the third switch is electrically connected to the controller, and before the lifting assembly 5 operates after the hull 1 sits on the bottom, after the third switch is turned on, the jet water is sprayed out from the third nozzle 9 through the third connecting pipe to separate the soil around the pile shoe 3 from the pile shoe 3.

[0057] According to some embodiments of the present invention, a ballast assembly is provided to ensure that the ballast water in the ballast tank is slowly discharged, so that the weight of the hull 1 is kept substantially equal to the buoyancy. When the pile shoe 3 is about to be pulled out of the mud, an accident can be prevented due to a sudden drop in pile pulling resistance, which causes the platform to oscillate sharply up and down in the water.

[0058] According to some preferred embodiments of the present invention, the ballast assembly includes a centrifugal drainage pump and a submersible drainage pump.

[0059] According to some preferred embodiments of the present invention, the ballast assembly slowly discharges the ballast water from the ballast tank, and the weight of the hull 1 is substantially equal to the buoyancy, to ensure that the hull 1 rises at a uniform speed when the lifting assembly 5 is not subjected to force.

[0060] The technical solution of the present invention is further explained below in conjunction with a specific embodiment. It should be noted that this specific embodiment is only for those skilled in the art to better understand the technical solution of the present invention, and should not be regarded as an unreasonable limitation on the protection scope of the present invention.

[0061] Embodiment 1

[0062] (1) Platform design: Estimate the pile pulling force based on the water depth and seabed geological conditions of the target operation site:

[0063] It is known that the water depth in a very shallow sea area is 4m, and the self-elevating platform weighs 6500t, of which the hull is 5000t and the pile shoes of the pile legs 2 are 1500t (4 groups). The main dimensions of the hull are 50×40×5.5m (length×width×height), the dimensions of the cylindrical pile legs 2 are 50m×ϕ3m, the dimensions of the pile shoes are 8×8×2.5m (length×width×height), and the dimensions of the mud guide groove are 9×9×3m (length×width×height). There are nozzles on the surface of the hull, pile shoes and mud guide groove. The pile insertion depth is about 15.1m, and the pile pulling resistance caused by the side friction of the pile shoes of the pile legs 2 and the weight of the soil covering the upper part of the pile shoes is about 1500t (single pile). The normal lifting capacity of the lifting assembly is 2000t, and the maximum lifting capacity is 3000t. When the platform is seated on the bottom, the hull displacement is about 7500t, and the maximum buoyancy that a single set of pile legs and two pile shoes can provide is about 75t. According to preliminary estimates, even if diagonal pile pulling operations are adopted, relying solely on the buoyancy of the platform's main hull, the maximum single pile pulling force that can be provided is 950t, which cannot overcome the pile pulling resistance of 1800t.

[0064] To this end, the technical considerations for platform bottom seating and pile pulling are proposed, and the pile pulling process is realized by using the interaction force between the platform and the seabed. First, the lifting capacity of the lifting assembly is checked. Combined with the requirement of overcoming the pile pulling resistance of 1800t, the normal lifting capacity of the lifting assembly is designed to be 2000t, which is greater than the pile pulling resistance of 1800t and meets the pile pulling requirements. When pulling piles, the main hull can be regarded as a sinking pad. In addition to meeting the conventional design requirements, its structure should also refer to the relevant specifications for the sinking pad design to strengthen the bottom plate structure to meet the requirements of bottom seating and pile pulling. In this case, the design requirements of the platform sinking pad in the classification specifications are adopted. According to the maximum lifting capacity of the lifting assembly of 3000t and the combined effect of 4 meters of seawater, the maximum equivalent water pressure head on the bottom plate is calculated to be about 12.57m. When designing the hull structure, the design pressure head on the bottom plate should take this value.

[0065] (2) Before pulling out the piles, the seabed should be investigated and processed to ensure that it is as flat as possible to avoid local hard protrusions on the seabed that may cause the bottom plate of the platform to be sunken and damaged, resulting in water ingress.

[0066] (3) After leveling, the hull is lowered into the water through the lifting assembly, and then the ballast assembly is started. During the lowering process in the water, ballast water is continuously injected into the ballast tank so that the buoyancy of the main hull of the platform remains basically equal to the weight of the main hull, that is, the platform lifting assembly is basically in a state of being free of stress.

[0067] (4) Lower the main hull of the platform into the water until the bottom plate contacts the seabed foundation (which can be determined by the draft).

[0068] (5) Open the third nozzle around the pile shoe to spray and reduce the adsorption force between the pile shoe and the surrounding soil.

[0069] (6) The lifting assembly lifts the pile leg 2 until the pile leg 2 moves slowly upward, indicating that the pile shoe is loose. The lifting assembly is then used to adjust the pile pulling force to achieve pile pulling at the designed speed.

[0070] (7) After the pile shoe is out of the mud, stop pulling the pile. Open the first nozzle around the main hull bottom plate and the side plate to reduce the adsorption force between the hull and the surrounding soil. Then, the ballast water in the ballast tank is slowly discharged through the discharge assembly, and the hull floats up, completing the pile pulling process.

[0071] (8) The mud guide trough is sprayed by the second nozzle, and the mud brought out by the pile shoe is discharged from the side opening of the mud guide trough.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for pulling piles from a self-elevating platform, characterized in that: include: A hull, pile legs, pile shoes, a ballast assembly, a lifting assembly, a first nozzle and a third nozzle, wherein the pile legs include an upper portion of the pile legs inserted into the seawater and a lower portion of the pile legs inserted into the mud; the pile shoes are fixed to the lower portion of the pile legs; the third nozzle is arranged on the outer side wall of the pile shoes; the ballast assembly includes a ballast tank and a ballast pump, the ballast pump and the ballast tank are arranged inside the hull, and the ballast pump is suitable for injecting or discharging ballast water into the ballast tank; the lifting assembly includes an upper portion of the lifting assembly and a lower portion of the lifting assembly, The upper section of the lifting assembly is connected with the upper section of the pile leg by a latch, the lower section of the lifting assembly is fixedly connected with the hull, and the upper section of the lifting assembly is slidably connected with the lower section of the lifting assembly; the first nozzle is arranged on the outer side walls of the bottom plate and the side plate of the hull; the hull includes a mud guide groove, which is arranged on the bottom plate of the hull and is arranged around the pile leg; the inner side wall of the mud guide groove is inclined in a direction away from the hull to form a guide surface, and the inner side wall of the mud guide groove is provided with a second nozzle; Lowering the hull into the water via the lifting assembly; Start the ballast assembly and use the ballast pump to inject ballast water into the ballast tank so that the buoyancy of the platform hull is balanced with the weight of the hull; The lifting assembly is used to drive the hull to continue to move downward until the bottom plate of the hull contacts the seabed foundation; Open the third nozzle to spray and flush, and keep the lifting assembly in the state of lowering the platform until the pile legs loosen and start to move upward; Continue to use the lifting assembly to pull the pile shoe out of the mud, then stop pulling the pile; Open the first nozzle for spraying, and use the ballast pump to discharge the ballast water in the ballast tank until the bottom of the hull is loosened, and the hull drives the pile legs and pile shoes to float, completing the pile pulling process.

2. The method for pulling piles from the bottom of a self-elevating platform according to claim 1, characterized in that: During the period of pulling up the pile shoe, the method further comprises the following steps: opening the second nozzle to spray and flush the soil in the mud guide groove.

3. The method for pulling piles from the bottom of a self-elevating platform according to claim 2, characterized in that: A watertight double bottom is arranged inside the hull.

4. The method for pulling piles from the bottom of a self-elevating platform according to claim 3, characterized in that: The size of the mud guide groove is larger than that of the pile shoe.

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