A method of float-over installation of a floating oil and gas platform

Abstract

The present application relates to a kind of floating oil and gas platform float installation method, it belongs to floating oil and gas platform installation field;Engineering ship is anchored with the transport ship loaded with upper block, and float is in and is in place;Flat tide is connected by control cable A between float and engineering ship, and float is submerged under ballast when following current;Float is connected by control cable B with transport ship, and control cable A is released;When top current, control tugboat is dragged to the direction of transport ship and moves to the upper block directly below by float;Float is fixed after being lifted and being connected with the upper block;Continue to be lifted by unloading, so that the upper block leaves transport ship deck, and control tugboat is dragged to leave transport ship by oil and gas platform as a whole;By "anchoring fixed point+control cable", stable constraint is provided in critical operation stage, and each step is accurately planned with the cooperation of sea condition, the adverse effects of environment are converted into stable factor, and high stability and high safety operation of whole process of float in open sea are realized, such as diving, moving and docking.

Description

Technical Field

[0001] This invention relates to a method for installing a floating oil and gas platform, which belongs to the field of floating oil and gas platform installation. Background Technology

[0002] The offshore installation of floating oil and gas platforms, especially those with large topside modules and deep-draft buoys, is a technically complex, high-risk operation severely constrained by environmental conditions. Traditional installation methods often employ large floating cranes for lifting, but this requires extremely high-capacity lifting resources, is costly, is greatly affected by sea conditions, and has a short operational window.

[0003] Float-over installation is an alternative method. Its principle involves pre-loading the superstructure onto a transport barge and delivering it to the site, while simultaneously towing the lower floating body to the site and submerging it under ballast. The floating body then rises and docks with the superstructure. This method reduces reliance on ultra-large floating cranes. However, during operation, the existing float-over installation method is highly susceptible to environmental loads such as tides and waves during the submerging and horizontal movement phases, resulting in significant drift and swaying. This leads to poor positioning accuracy, docking difficulties, and even the risk of collision, making safety difficult to guarantee.

[0004] Therefore, how to provide a safer, more economical, and more efficient method for installing floating oil and gas platforms, and achieve precise and stable control of the installation process to improve docking accuracy, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a floating installation method for a floating oil and gas platform.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0007] A method for installing a floating oil and gas platform includes the following steps:

[0008] Step S1: The engineering vessel and the transport vessel carrying the superstructure are both anchored in the direction of the current. The main tugboat and the control tugboat jointly tow the floating body into the site and position it at the designated location between the engineering vessel and the transport vessel carrying the superstructure.

[0009] Step S2: During low tide, the operator connects the float to the engineering vessel via control cable A. During downstream, the float is ballasted and submerged. The control cable A provides a force to counteract the tidal current, making the float submerge more stably.

[0010] Step S3: After the ballast is completed, the buoy is connected to the transport ship via control cable B during low tide, and then the control cable A between the buoy and the engineering vessel is released.

[0011] Step S4: When facing the current, control the tugboat to tow the float towards the transport ship. Use cable B to provide the force to counteract the current and control the tugboat to provide the power to move the float to the upper block and make minor left and right adjustments, so that the float moves more stably until the float moves directly below the upper block.

[0012] Step S5: During low tide, the float is loaded and floats up. After the float is docked with the upper module, the floating is stopped and the docking point is fixed.

[0013] In step S6, the float continues to be loaded and floated up, causing the upper module to leave the transport ship's deck. The tugboat or a combined main tugboat is then used to tow the oil and gas platform away from the transport ship as a whole, thus completing the float installation.

[0014] Furthermore, in step S1, both the engineering vessel and the transport vessel are arranged along the current, with a safety distance of 1km-1.2km reserved.

[0015] Furthermore, in step S2, the control cable A is connected to the engineering vessel which is in an anchored state.

[0016] Furthermore, in step S6, the distance between the upper module and the deck of the transport ship is a safe distance, which specifically refers to the distance that ensures no interference between the upper module and any protrusions on the deck of the transport ship.

[0017] Furthermore, the floating process in step S5 is carried out in stages. In the first stage, the amount of buoy is precisely controlled so that when the floating body floats to the position where the top structure and the bottom structure of the upper block are initially in contact or closely aligned, the upper block and the floating body are immediately mechanically locked or initially welded together. In the second stage, the permanent welding and fixing work at the docking interface is quickly completed during the slack tide window.

[0018] Furthermore, in step S3, the completion of ballast loading of the floating body refers to ballasting to a predetermined depth. The predetermined depth means that, under a predetermined draft, the upper cone of the upper block and the top of the docking coupling device of the floating body's pile legs maintain a safe distance of at least one meter.

[0019] Furthermore, the transport vessel is a non-powered barge.

[0020] Furthermore, the transport vessel is a T-shaped barge.

[0021] Furthermore, the engineering vessel can be replaced by an anchored work vessel.

[0022] Furthermore, the control cable A is a cable carried on the engineering vessel, and the control cable B is a cable carried on the transport vessel. The control cable A is usually controlled by a large winch on the engineering vessel.

[0023] The beneficial effects of this invention are: by using "anchoring fixed points + control cables" to provide stable constraints in key operation stages, and by precisely planning the coordination of each step with sea conditions (slack tide, downstream current, and upstream current), the adverse effects of the environment are transformed into stabilizing factors, thereby achieving high stability and high safety operation of the floating body in the entire process of diving, moving and docking in open sea areas.

[0024] Effectively suppressing the influence of tidal currents and improving operational stability: By cleverly utilizing two anchoring points, “engineering vessel-control cable A” and “transport vessel-control cable B”, stable reverse restraint forces are provided during the submersion and horizontal movement phases of the float, respectively, which significantly offsets the direct pushing effect of tidal currents on the float and greatly reduces the drift and lateral sway amplitude of the float during critical operational phases.

[0025] Precisely utilizing sea state windows enhances operational efficiency and safety: The method clearly defines the timing for operations such as connecting cables during slack tide, diving with the current, moving against the current, and docking and surfacing during slack tide. During slack tide, the current velocity is low, facilitating delicate operations such as cable connection and precise docking. When diving with the current and moving against the current, the constraint force of the control cable and the tidal force are used to form a dynamic balance, transforming the unfavorable tidal environment into favorable conditions that help stabilize the floating body's attitude, thus improving the controllability and safety of the operation.

[0026] Optimized work process with clear logic: The entire installation process has clear steps and distinct stages. By controlling the "connection-transfer-release" of the control cable, a smooth transition of the floating body from entering the site, diving, moving to docking and floating is achieved, avoiding the risks caused by work interruption and sudden changes in state.

[0027] Reduced dependence on external resources: Compared to relying entirely on high-horsepower tugboats for dynamic positioning (DP) to resist tidal currents, this invention reduces the highest level of capability requirements and fuel consumption of the tugboat's dynamic positioning system by combining the passive constraint of "anchored vessel + cable" with the active towing of the tugboat, making it more economical while ensuring safety. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the ship's positioning and the arrival of the floating body in this invention.

[0029] Figure 2 This is a schematic diagram showing the buoy beginning to submerge after it is connected to the control cable of the engineering vessel in this invention.

[0030] Figure 3 This is a schematic diagram showing the connection between the float and the control cable B of the transport ship in this invention.

[0031] Figure 4 This is a schematic diagram of the floating body moving against the current in this invention.

[0032] Figure 5 This is a schematic diagram showing the docking and fixing of the float and the upper module in this invention.

[0033] Figure 6 This is a side view of the float after it is docked with the upper module in this invention.

[0034] Figure 7 This is a schematic diagram of the upper module being towed away as a whole after it has successfully docked with the floating body in this invention.

[0035] In the diagram, 1. Upper module; 2. Floating body; 3. Transport vessel; 4. Engineering vessel; 5. Main tugboat; 6. Control tugboat; 7. Anchor cable; 8. Control cable A; 9. Control cable B; 10. Overall oil and gas platform. Detailed Implementation

[0036] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0037] like Figure 1-7 As shown in the figure, the specific implementation steps of the floating platform buoy installation method in this embodiment are as follows:

[0038] Step S1: Ship positioning and buoy 2 entry;

[0039] Select a relatively stable operating window with a stable current direction, and anchor the engineering vessel 4 (which may be an anchoring work vessel) and the transport vessel 3 (usually a T-shaped barge) loaded with the upper module 1 along the current direction (as shown by the arrow in the figure) using anchor cables 7; the two vessels, the transport vessel 3 and the engineering vessel 4, are basically arranged along the current direction, with a safety water area of ​​1km-1.2km reserved; then, the main tugboat 5 and the control tugboat 6 jointly tow the floating body 2 into the operating area and position the floating body 2 at the predetermined position between the engineering vessel 4 and the transport vessel 3;

[0040] Step S2: Connect cable A8 and submerge float 2;

[0041] While waiting for the low tide to arrive, the operators complete the connection of the control cable A8 between the floating body 2 and the anchored engineering vessel 4; the control cable A8 is usually controlled by a large winch on the engineering vessel 4.

[0042] Once the current turns to the downstream (assuming the direction of movement toward transport ship 3 is downstream), ballast is applied to float 2 to allow it to slowly submerge. During this process, the downstream current exerts a forward thrust on float 2, while the taut control cable A8 provides a reverse restraining force. These two forces form a pair of balanced forces, which greatly suppress the horizontal movement of float 2 in the cross-current direction (i.e., perpendicular to the current direction), allowing float 2 to submerge stably in a basically vertical direction, avoiding the risk of control difficulties or collisions with surrounding ships caused by large swaying.

[0043] Step S3: Connect control cable B9;

[0044] After the float 2 is ballasted to the predetermined depth, wait for the slack tide period to arrive again; under calm sea conditions, complete the connection of control cable B9 between float 2 and the transport vessel 3 of the upper module 1; after the connection is completed, release control cable A8 between float 2 and the engineering vessel 4. At this time, float 2 forms a new constraint relationship with transport vessel 3 through control cable B9; the predetermined depth refers to the safe distance of at least one meter between the upper cone of the upper module 1 and the top of the docking coupling device of the float 2's pile legs under the predetermined draft conditions;

[0045] Step S4: Float 2 moves against the current;

[0046] When the current turns into the top current, start the control tugboat 6 to tow the floating body 2 horizontally towards the transport ship 3;

[0047] During the movement, the current exerts a thrust on the float 2 in the opposite direction to the transport ship 3, while the taut control cable B 9 provides a restraining pull in the direction of the transport ship 3. Similarly, this force effectively balances the interference in the cross-current direction (i.e., perpendicular to the current direction), significantly reducing the lateral drift and sway of the float 2 during the movement. The control tugboat 6 is mainly responsible for providing forward power and making fine adjustments to the left and right positions, so that the float 2 can move smoothly along the predetermined precise path to directly below the upper block 1.

[0048] Step S5: Docking and securing;

[0049] After the float 2 is precisely positioned directly below the upper module 1, it waits for the next slack tide window; under calm sea conditions with low current speed, a controlled unloading operation is started on the float 2 to make it slowly and vertically rise to the surface;

[0050] The loading and floating of float 2 is preferably carried out in stages: In the first stage, the loading volume is precisely controlled so that when float 2 floats to the position where its top structure just touches or is closely aligned with the bottom structure of the upper block 1, the two are immediately mechanically locked or initially connected; In the second stage, the permanent welding and fixing work at the docking interface is quickly completed during the slack tide window.

[0051] Step S6: Unload and float to the surface, then tow the entire structure away;

[0052] After the docking welding is completed, continue to unload the float 2, and at the same time drive the upper block 1 to float up as a whole until the bottom of the upper block 1 reaches a safe distance from the deck of the transport ship 3 (this distance must ensure that the upper block 1 does not interfere with any equipment, supports or protrusions on the deck of the transport ship 3 during the floating and subsequent movement).

[0053] Finally, the control tugboat 6 (or the combined main tugboat 5) tows the integrated oil and gas platform 10 away from the transport vessel 3, and transports it to the final installation location or to carry out the next step of the operation. At this point, the entire floating installation process is completed.

[0054] This invention provides stable constraints during critical operational phases through "anchorage points + control cables" and precisely plans the coordination of each step with sea conditions (slack tide, downstream, and upstream), transforming adverse environmental forces into stabilizing factors. This achieves high stability and safety throughout the entire process of buoy 2's submersion, movement, and docking in open sea areas. It effectively suppresses tidal influences and improves operational stability: by cleverly utilizing two anchorage points, "engineering vessel 4 - control cable A 8" and "transport vessel 3 - control cable B 9," stable reverse constraints are provided during buoy 2's submersion and horizontal movement phases, significantly offsetting the direct thrust of tidal currents on buoy 2 and greatly reducing its drift and lateral swaying amplitude during critical operational phases. It precisely utilizes sea condition windows to improve operational efficiency and safety: the method clearly specifies the timing for operations such as "slack tide" cable connection, "downstream" submersion, "upstream" movement, and "slack tide" docking and surfacing. The low current velocity during certain periods facilitates delicate operations such as cable connection and precise docking. When diving with the current and moving against the current, the constraint force of the control cable and the tidal force are dynamically balanced, transforming the unfavorable tidal environment into favorable conditions that help stabilize the attitude of the float 2, thus improving the controllability and safety of the operation. The optimized operation process is logically clear: the entire installation process is clearly defined in steps and stages. By controlling the "connection-transfer-release" of the control cable, a smooth transition of the float 2 from the arrival, diving, and movement to docking and floating is achieved, avoiding the risks caused by operation interruption and sudden changes in state. The dependence on external resources is reduced: compared to relying entirely on high-horsepower tugboats for dynamic positioning (DP) to resist tidal currents, this invention combines the passive constraint of "anchor boat + cable" with the active towing of tugboats, reducing the highest level of capability requirements and fuel consumption of the tugboat dynamic positioning system, making it more economical while ensuring safety.

[0055] 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for installing a floating support structure on a floating oil and gas platform, characterized in that: Includes the following steps: Step S1: The engineering vessel (4) and the transport vessel (3) carrying the superstructure (1) are both anchored in the direction of the current. The main tugboat (5) and the control tugboat (6) jointly tow the floating body (2) into the field and place it in the designated position between the engineering vessel (4) and the transport vessel (3) carrying the superstructure (1). In step S2, during low tide, the operator connects the float (2) to the engineering vessel (4) via control cable A (8). During downstream, the float (2) is ballasted and submerged. The control cable A (8) provides a force to counteract the tidal current, making the float (2) submerge more stably. Step S3: After the ballast of the float (2) is completed, the float (2) is connected to the transport ship (3) by the control cable B (9) during the slack tide. Then the control cable A (8) between the float (2) and the engineering ship (4) is released. Step S4: When facing the current, control the tugboat (6) to tow the floating body (2) towards the transport ship (3), and provide the force to counteract the current by controlling the cable (9), and provide the power to move the upper block (1) and make slight left and right adjustments by controlling the tugboat (6), so that the floating body (2) is more stable when moving, until the floating body (2) moves directly below the upper block (1); Step S5: During low tide, the float (2) is loaded and floats up. After the float (2) is docked with the upper block (1), the float stops floating and the docking point is fixed. In step S6, the float (2) continues to be loaded and floated up, so that the upper module (1) leaves the deck of the transport ship (3), and the tugboat (6) or the combined main tugboat (5) tows the oil and gas platform as a whole (10) away from the transport ship (3), thus completing the float installation.

2. The floating platform installation method according to claim 1, characterized in that: In step S1, both the engineering vessel (4) and the transport vessel (3) are arranged along the current and a safe distance of 1km-1.2km is reserved.

3. The floating platform installation method according to claim 1, characterized in that: In step S2, the control cable A (8) is connected to the engineering vessel (4) which is in an anchored state.

4. The floating platform buoy installation method according to claim 1, characterized in that: In step S6, the distance between the upper block (1) and the deck of the transport ship (3) is a safe distance. Specifically, the safe distance refers to the distance that ensures no interference between the upper block (1) and the protrusions on the deck of the transport ship (3).

5. The floating platform installation method according to claim 1, characterized in that: In step S5, the floating body (2) is loaded and floated in stages. In the first stage, the loading amount is precisely controlled so that when the floating body (2) floats to the position where the top structure and the bottom structure of the upper block (1) are initially in contact or closely aligned, the upper block (1) and the floating body (2) are immediately mechanically locked or initially welded together. In the second stage, the permanent welding and fixing work at the docking interface is quickly completed during the slack tide window.

6. The floating platform installation method according to claim 1, characterized in that: In step S3, the completion of ballasting of the float (2) means ballasting to a predetermined depth. The predetermined depth means that, under a predetermined draft, the upper cone of the upper block (1) and the top of the coupling device of the pile leg of the float (2) maintain a safe distance of at least one meter.

7. The floating platform installation method according to claim 1, characterized in that: The transport vessel (3) is a non-powered barge.

8. The floating platform installation method according to claim 1, characterized in that: The transport vessel (3) is a T-type barge.

9. The floating platform installation method according to claim 1, characterized in that: The engineering vessel (4) can be replaced by an anchored work vessel.

10. The floating platform installation method according to claim 1, characterized in that: The control cable A (8) is a cable carried on the engineering vessel (4), and the control cable B (9) is a cable carried on the transport vessel (3). The control cable A (8) is controlled by a large winch on the engineering vessel (4).

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