A deep-water installation device and method for a cylindrical foundation

Abstract

The present invention relates to a deep-water installation device and method for a barrel foundation, the device comprises a continuous oil pipe, a conversion joint, a release device and a barrel foundation; wherein the lower end of the continuous oil pipe is connected to the conversion joint, and the upper end is connected to a high-pressure gas source, a pressure relief valve and a guide hole are provided on the barrel foundation, and the upper end of the guide hole is connected to the lower end of the conversion joint through a release device; the method utilizes the principle of the floating method, inputs high-pressure air into the barrel foundation through the continuous oil pipe, thereby controlling the buoyancy of the barrel foundation, and combines the closing of the pressure relief valve to adjust the stability and sinking speed of the barrel foundation, while reducing the tension of the continuous oil pipe; when the barrel foundation sinks to the bottom of the water, the water and air inside it are pumped out through the continuous oil pipe, so that negative pressure is formed inside the barrel foundation, and the barrel foundation is sunk into the mud by its own weight and external water pressure. The device and method of the present invention effectively reduce the installation difficulty of the barrel foundation, and the device has a simple structure, is easy to operate, and has a great application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater wellhead installation, and in particular to a deepwater installation device and method for a cylindrical foundation. Background Art

[0002] At present, the cylindrical foundation adopts a cylindrical structure with a closed upper end and an open lower end. It is mainly used in fixed platforms, SPAR platforms, semi-submersible platforms, tension leg platforms, underwater production systems, offshore wind turbines, etc. to assist in the construction of underwater wellheads.

[0003] With the continuous development of my country's seabed resources, barrel foundations are increasingly used as installation platforms for underwater equipment in various seabed development projects. At present, barrel foundations are often installed by hoisting into the water. In deep-sea environments, due to the long suspension cables used, barrel foundations are easily affected by waves and currents, which can easily lead to hard pulling between the barrel foundation and the suspension ropes, and then the tension between the two is too large, resulting in damage to the suspension ropes or barrel foundations. In addition, it is difficult to control the sinking speed and stability during the sinking process, and it is impossible to complete the installation of the barrel foundation with high quality. Summary of the invention

[0004] In view of this, in order to control the sinking speed and stability of the cylindrical foundation and avoid damage to both parties due to excessive tension generated by the cylindrical foundation on the suspension rope, an embodiment of the present invention provides a deep-water installation device and method for a cylindrical foundation.

[0005] A deepwater installation device for a cylindrical foundation in the present invention comprises:

[0006] A barrel foundation with a closed top and open bottom;

[0007] A guide hole is arranged on the central axis of the cylindrical foundation, the upper end of which passes through the upper end surface of the cylindrical foundation from bottom to top and extends to the upper part of the cylindrical foundation;

[0008] A release device is arranged above the cylindrical foundation, and its lower end is sleeved on the upper end of the guide hole;

[0009] A conversion joint, the lower end of which is connected to the release device and is in close contact with the upper end of the guide hole;

[0010] and a coiled oil pipe, the lower end of which is connected to the conversion joint and the upper end of which is connected to a high-pressure air source on the ground;

[0011] The high-pressure air injected by the continuous oil pipe is input into the interior of the cylindrical foundation through the guide hole, so that during the sinking process of the cylindrical foundation, a part of its upper part is always air, which increases its buoyancy and thereby reduces the tension on the continuous oil pipe. At the same time, the sinking speed of the cylindrical foundation is controlled by controlling the flow rate of the high-pressure air injection.

[0012] Furthermore, the guide hole has a tubular shape, and its lower end is located in the middle of the cylindrical foundation.

[0013] Furthermore, it comprises at least one pressure relief valve, each of which is arranged on the upper end surface of the cylindrical foundation, and all of the pressure relief valves are communicatively connected with a controller on the ground.

[0014] Furthermore, the release device is used to separate the conversion joint from the cylindrical foundation.

[0015] Furthermore, the conversion joint is tightly connected to the coiled tubing and sealed to the release device.

[0016] Furthermore, an underwater gyro compass and an inclinometer are provided on the outer wall of the cylindrical foundation, and both the underwater gyro compass and the inclinometer are communicatively connected with a display on the ground. According to the deep-water installation device of the cylindrical foundation, an installation method is proposed, and the installation method comprises the following steps:

[0017] S1. Using the principle of the floating method, high-pressure air is injected into the cylindrical foundation so that a portion of the upper part is always filled with air during the sinking process. At the same time, the closing of the pressure relief valve and the flow rate of the high-pressure air injection are combined to control the sinking speed of the cylindrical foundation and ensure its steady sinking;

[0018] S2, when the cylindrical foundation reaches the bottom of the water, gradually reduce the injection flow of the high-pressure air, open the pressure relief valve, and gradually reduce the volume occupied by the air in the cylindrical foundation, so that the cylindrical foundation sinks into the mud surface of the bottom of the water by its own weight;

[0019] S3. After the cylindrical foundation sinks to a certain depth under its own weight, the pressure relief valve is closed, and the remaining air and water in the cylindrical foundation are pumped out through the coiled tubing to form a negative pressure inside the cylindrical foundation. Combined with the external water pressure, the cylindrical foundation continues to sink to the set depth of penetration;

[0020] S4. Perform the coiled tubing release operation and release and separate the coiled tubing from the cylindrical foundation using a release device.

[0021] The technical solution provided by the embodiments of the present invention has the following beneficial effects: a deep-water installation device and method for a cylindrical foundation are provided, wherein high-pressure air is injected into the cylindrical foundation so that a portion of the upper part thereof is always air during the sinking process, thereby increasing the buoyancy received, thereby reducing the tension received by the continuous oil pipe, and avoiding damage to the two; the buoyancy received by the cylindrical foundation is adjusted by controlling the flow of high-pressure air and the closing of the pressure relief valve, thereby controlling the sinking speed thereof and ensuring smooth sinking; the device has a simple overall structure and an easy operation method, and can reduce the installation cost while ensuring the installation quality of the cylindrical foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a deep-water installation device of a cylindrical foundation of the present invention;

[0023] Figure 2 yes Figure 1 A top view of the device;

[0024] Figure 3 yes Figure 1 Schematic diagram of the internal situation of the middle barrel foundation 5 during the sinking process;

[0025] Figure 4 yes Figure 1 Schematic diagram of adjusting the stability when the middle cylindrical foundation 5 tilts during the sinking process;

[0026] Figure 5 It is a flow chart of an installation method of a deep-water installation device for a cylindrical foundation of the present invention;

[0027] Figure 6 yes Figure 1 Schematic diagram of the middle cylindrical foundation 5 sinking into the mud surface of the water bottom by its own gravity;

[0028] Figure 7 yes Figure 1 Schematic diagram of the installation of the middle cylindrical foundation 5 by water pressure;

[0029] In the figure: 1-coiled tubing, 2-conversion joint, 3-release device, 4-pressure relief valve, 5-cylindrical foundation, 6-guide hole, 7-air, 8-water, 9-mud surface. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0031] Please refer to Figure 1 and Figure 2The embodiment of the present invention provides a deep-water installation device and method for a cylindrical foundation, which is mainly used in the field of underwater wellhead installation. The installation device mainly includes: a continuous oil pipe 1, a conversion joint 2, a release device 3 and a cylindrical foundation 5.

[0032] The cylindrical foundation 5 is a steel thin-walled cylindrical structure with a closed upper end and an open lower end, and the release device 3 is provided at the upper end thereof. The conversion joint 2 is provided at the lower end of the continuous oil pipe 1, and the upper end is connected to the high-pressure gas source on the ground. The conversion joint 2 is connected to the release device 3, so that the high-pressure air output by the high-pressure gas source can be injected into the cylindrical foundation 5 through the continuous oil pipe 1, so that the buoyancy of the cylindrical foundation 5 can be adjusted by controlling the flow rate of the high-pressure air injection, thereby reducing the tension of the continuous oil pipe 1 and controlling the sinking speed of the cylindrical foundation 5 underwater.

[0033] A guide hole 6 is provided inside the cylindrical foundation 5 along the central axis. The guide hole 6 is a tubular structure, and its upper end passes through the upper end surface of the cylindrical foundation 5 and extends to the upper part of the cylindrical foundation 5. The lower end of the releaser 3 is sleeved on the upper end of the guide hole 6, and the upper port of the guide hole 6 is located inside the releaser 3. The lower end of the conversion joint 2 is connected to the releaser 2 from top to bottom and is in close contact with the upper port of the guide hole 6, so that the high-pressure air output by the high-pressure air source on the ground can be injected into the cylindrical foundation 5.

[0034] The release device 2 is used to separate the cylindrical foundation 5 from the conversion joint 2, so that the coiled tubing 1 can be separated from the cylindrical foundation 5 after the cylindrical foundation 5 is installed.

[0035] Please refer to Figure 3 The lower end of the guide hole 6 is located in the middle of the cylindrical foundation 5, so that it can guide the high-pressure air injected into the cylindrical foundation 5, so that the upper part of the cylindrical foundation 5 is air 7 and the lower part is water 8 during the sinking process. The buoyancy of the cylindrical foundation 5 is adjusted by controlling the volume of the air 7 on the upper part of the cylindrical foundation 5, so that the tension on the coiled tubing 1 can be reduced and the sinking speed of the cylindrical foundation 5 can be controlled. At the same time, the water inside the cylindrical foundation 5 can be pumped out according to needs.

[0036] A pressure relief valve 4 is provided at the upper end of the cylindrical foundation 5, and the pressure relief valve 4 is communicated with a controller on the ground. The controller can control the closing of the pressure relief valve 4. The pressure relief valve 4 is used to adjust the volume of the high-pressure air inside the cylindrical foundation 5, so that the sinking speed of the cylindrical foundation 5 can be controlled in combination with the flow rate of the high-pressure air injection.

[0037] Please refer to Figure 4 When the cylindrical foundation 5 tilts during the sinking process, the pressure relief valve 4 is opened and the high-pressure air injection flow rate is reduced to reduce the air volume above the cylindrical foundation 5. In this way, the stability can be adjusted by utilizing the own gravity of the cylindrical foundation 5, the traction force generated by the continuous oil pipe 1 on the cylindrical foundation 5, and the buoyancy of the cylindrical foundation 5.

[0038] The outer wall of the cylindrical foundation 5 is provided with an underwater electric compass and an inclinometer, which are used to detect whether the cylindrical foundation 5 is tilted during the sinking process. The underwater electric compass and the inclinometer are communicated with a display on the ground, so that whether the cylindrical foundation 5 is tilted can be observed in real time through the display on the ground.

[0039] Corresponding to the specific device in this embodiment, the basic parameters of the cylindrical foundation in this embodiment are that the outer diameter D of the cylinder is 6m, the height L is 12m, the wall thickness δ is 30mm, the weight is 134t, and the seawater density ρ w The pressure at the output end of the high-pressure gas source is set to 20 MPa. The speed v during the sinking of the cylindrical foundation is 3 m / min, and the seawater depth is 1500 m.

[0040] Please refer to Figure 5 and Figure 6 This embodiment provides an installation method according to the deepwater installation device of the cylindrical foundation, which includes the following steps:

[0041] S1. Using the principle of the floating method, high-pressure air is injected into the cylindrical foundation so that there is always a part of air on the upper part during the sinking process. At the same time, the closing of the pressure relief valve and the flow rate of the high-pressure air injection are combined to control the sinking speed of the cylindrical foundation and ensure its smooth sinking.

[0042] By controlling the flow rate of high-pressure air injected into the cylindrical foundation 5 by the high-pressure air source, a part of the seawater inside the cylindrical foundation 5 is discharged, and the volume of the high-pressure air inside the cylindrical foundation 5 is adjusted in combination with the closing of the pressure relief valve 4, thereby adjusting the buoyancy of the cylindrical foundation, thereby controlling its sinking speed and reducing the tension on the coiled tubing 1. At the same time, the coiled tubing 1 will generate a traction force on the cylindrical foundation 5 while being subjected to tension, so as to ensure that the cylindrical foundation 5 can sink smoothly. According to the sinking speed set for the cylindrical foundation 5, the flow rate of the air injected into the cylindrical foundation 5 by the high-pressure air source can be calculated according to the following formula:

[0043]

[0044] Where, Q is the flow rate of high-pressure air injected into the cylindrical foundation 5, ρ w is the density of seawater, V is the volume of seawater discharged from the cylindrical foundation, g is the acceleration of gravity, v is the sinking speed set for the cylindrical foundation, P0 is the air pressure at the output end of the high-pressure air source, l is the height occupied by the air in the cylindrical foundation, D is the outer diameter of the cylindrical foundation, δ is the wall thickness of the cylindrical foundation, and d is the diameter of the guide hole.

[0045] During the sinking process of the cylindrical foundation 5 , the pressure relief valve 4 can be closed by observing the information fed back by the underwater gyrocompass and the inclinometer, so as to adjust the volume of the high-pressure air inside the cylindrical foundation 5 .

[0046] S2. When the cylindrical foundation reaches the bottom of the water, the high-pressure air injection flow rate is gradually reduced, and the pressure relief valve is opened to gradually reduce the volume occupied by the air in the cylindrical foundation, so that the cylindrical foundation can sink into the mud surface at the bottom of the water by its own weight.

[0047] When the cylindrical foundation 5 contacts the bottom mud surface, the high-pressure air injection flow rate is gradually reduced, and combined with the closing of the pressure relief valve 4, the air volume inside the cylindrical foundation is gradually reduced, and then the cylindrical foundation is sunk into the mud surface by its own weight. The depth h of the cylindrical foundation 5 penetrating into the mud surface by its own weight can be calculated according to the following formula: G :

[0048] N tip +N side =G'

[0049]

[0050]

[0051]

[0052]

[0053] Where N tip is the resistance on the end of the cylindrical foundation, N side is the friction force on the side wall of the cylindrical foundation, G' is the floating weight of the cylindrical foundation, G is the deadweight of the cylindrical foundation, A tip is the circular surface area of ​​the cylindrical foundation end, N c is the bearing capacity coefficient of the barrel foundation in clay, is the average undrained strength of the soil under the barrel foundation, γ is the effective unit density of the sea soil, h G is the self-weight penetration depth, is the average shear strength of the sea soil from the seabed surface to the penetration depth, α = 1 / S t, where S t The sensitivity of the clay.

[0054] S3. After the cylindrical foundation sinks to a certain depth in the mud surface under water by its own weight, close the pressure relief valve, extract the remaining air and water in the cylindrical foundation through the continuous oil pipe, so that negative pressure is formed inside it, and the cylindrical foundation continues to sink and penetrate into the mud until the set depth of penetration is reached in combination with the external water pressure.

[0055] After the cylindrical foundation 5 penetrates the mud surface by its own weight, the pressure relief valve 4 is closed, and the remaining air and water inside the cylindrical foundation 5 are extracted through the high-pressure air source, so that the inside of the cylindrical foundation 5 is in a negative pressure state, and the pressure difference formed by the external seawater is used to make the cylindrical foundation 5 sink to the set mud penetration depth, thereby completing the installation of the cylindrical foundation.

[0056] S4. Perform the coiled tubing release operation and release and separate the coiled tubing from the cylindrical foundation using a release device.

[0057] In this document, the directional words such as front, back, top, and bottom are defined by the positions of the components in the drawings and the positions of the components relative to each other, and are only for the sake of clarity and convenience in expressing the technical solution. It should be understood that the use of the directional words should not limit the scope of protection claimed in this application.

[0058] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for installing a deepwater installation device for a cylindrical foundation, characterized in that: A deepwater installation device comprising a barrel foundation, the deepwater installation device comprising: A barrel foundation with a closed top and open bottom; A guide hole is arranged on the central axis of the cylindrical foundation, the upper end of which passes through the upper end surface of the cylindrical foundation from bottom to top and extends to the upper part of the cylindrical foundation; A release device is arranged above the cylindrical foundation, and its lower end is sleeved on the upper end of the guide hole; A conversion joint, the lower end of which is connected to the release device and is in close contact with the upper end of the guide hole; At least one pressure relief valve, each of which is disposed on the upper end surface of the cylindrical foundation, and all of which are in communication connection with a controller on the ground; and a coiled oil pipe, the lower end of which is connected to the conversion joint and the upper end of which is connected to a high-pressure air source on the ground; The high-pressure air injected by the coiled tubing is input into the interior of the cylindrical foundation through the guide hole, so that during the sinking process of the cylindrical foundation, a part of the upper part thereof is always filled with air, thereby increasing its buoyancy and thereby reducing the tension on the coiled tubing. At the same time, the sinking speed of the cylindrical foundation is controlled by controlling the flow rate of the high-pressure air injection; The installation method comprises the following steps: S1. Using the principle of the floating method, high-pressure air is injected into the cylindrical foundation so that a portion of the upper part is always filled with air during the sinking process. At the same time, the closing of the pressure relief valve and the flow rate of the high-pressure air injection are combined to control the sinking speed of the cylindrical foundation and ensure its steady sinking; S2, when the cylindrical foundation reaches the bottom of the water, gradually reduce the injection flow of the high-pressure air, open the pressure relief valve, and gradually reduce the volume occupied by the air in the cylindrical foundation, so that the cylindrical foundation sinks into the mud surface of the bottom of the water by its own weight; S3. After the cylindrical foundation sinks to a certain depth under its own weight, the pressure relief valve is closed, and the remaining air and water in the cylindrical foundation are pumped out through the coiled tubing to form a negative pressure inside the cylindrical foundation. Combined with the external water pressure, the cylindrical foundation continues to sink to the set depth of penetration; S4. Perform the coiled tubing release operation and release and separate the coiled tubing from the cylindrical foundation using a release device.

2. The installation method of the deepwater installation device of the barrel foundation according to claim 1, characterized in that: The guide hole is tubular in shape, and its lower end is located in the middle of the cylindrical foundation.

3. The installation method of the deepwater installation device of the barrel foundation according to claim 1, characterized in that: The release device is used to separate the conversion joint from the cylindrical foundation.

4. The installation method of the deepwater installation device of the barrel foundation according to claim 1, characterized in that: The conversion joint is tightly connected to the coiled tubing and sealed to the release device.

5. The installation method of the deepwater installation device of the barrel foundation according to claim 1, characterized in that: An underwater gyro compass and an inclinometer are arranged on the outer wall of the cylindrical foundation, and both the underwater gyro compass and the inclinometer are communicatively connected with a display on the ground.

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