Method for converting towing and limiting modes of semi-submersible production platform

Abstract

The invention discloses a method for converting the towing and limiting modes of a semi-submersible production platform, and relates to the field of marine petroleum engineering technology. The operation steps are as follows: installing the platform towing rigging and limiting rigging on the platform; towing the semi-submersible production platform to the oil and gas field site by three tugboats; driving the towing tugboat 1, the towing tugboat 2 and the towing tugboat 3 to the predetermined position in turn, and transferring and connecting the platform limiting rigging, converting the towing tugboat 1, the towing tugboat 2 and the towing tugboat 3 into limiting tugboats; performing a limiting test on the semi-submersible platform by four limiting tugboats, and if the test meets the requirements, the subsequent mooring system can be reconnected. The invention can make the semi-submersible production platform seamlessly convert from the towing mode to the limiting mode, ensuring the smooth development of the subsequent reconnection and installation operations of the semi-submersible production platform, and at the same time, the invention method can greatly save the operation time of the conversion of the towing and limiting modes of the semi-submersible production platform.

Description

Technical Field

[0001] The invention relates to the technical field of offshore oil engineering, in particular to a method for converting towing and limiting modes of a semi-submersible production platform. Background Art

[0002] As the development of marine oil and gas resources gradually moves towards deep water, the technical and economic performance of conventional jacket platforms has gradually deteriorated. Floating production units have significant advantages in economy and reliability. Semi-submersible production platforms are one of the main types of deep-sea floating production units, with the advantages of a wide range of applicable working depths, large deck area, good motion performance, and portability and reusability.

[0003] A semi-submersible production platform consists of a platform body, columns and a lower body or pontoon. Its length and width are similar, which is very different from the ship structure of a floating production storage and offloading unit (FPSO). After the semi-submersible production platform is towed to the oil and gas field site, it needs to be seamlessly converted from the towing mode to the limiting mode, and the platform mooring system needs to be connected back within the shortest weather window to ensure the safety of the semi-submersible production platform. However, there is currently no systematic method. Therefore, a method for converting the towing and limiting modes of a semi-submersible production platform is proposed. Summary of the invention

[0004] The object of the present invention is to provide a method for converting the towing and limiting modes of a semi-submersible production platform to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a method for converting the towing and limiting modes of a semi-submersible production platform, the operating steps of which are as follows:

[0006] S1: Before towing the semi-submersible production platform, install the platform towing rigging and limit rigging on the platform in advance and tie them up and fix them;

[0007] S2: The semi-submersible production platform is towed to the oil and gas field site by three tugboats, and the platform begins to be ballasted, adjusting the platform from the towing draft to the limited draft;

[0008] S3: The limiting tugboat 1 travels to the predetermined position (set to the northeast side of the platform), controls the stern of the tugboat to be about 15-20 meters away from the semi-submerged platform, and the platform and the tugboat cooperate to transfer and connect the first platform limiting rigging;

[0009] S4: The tugboat 2 on the northeast side of the platform is released, and the tugboat 2 travels to the northwest side of the platform. The platform and the tugboat cooperate to transfer and connect the second platform limiting rigging, and the tugboat 2 is converted into a limiting tugboat;

[0010] S5: The tugboat 3 on the southeast side of the platform is released, and the platform and the tugboat cooperate to transfer and connect the third platform limiting rigging, and the tugboat 3 is converted into a limiting tugboat;

[0011] S6: The main tugboat 1 on the east side of the platform is released, and the tugboat 1 travels to the southwest side of the platform. The platform and the tugboat cooperate to transfer and connect the fourth platform limiting rigging, and the main tugboat 1 is converted into a limiting tugboat;

[0012] S7: The semi-submersible platform is tested for position limiting by four position limiting tugboats. If the test meets the requirements, the subsequent mooring system can be connected back.

[0013] Preferably in the present technical solution, the position-limiting rigging in step S1 includes a position-limiting main rigging and a position-limiting emergency rigging.

[0014] Preferably, in the technical solution, the steps of transferring and connecting the platform limiting rigging in step S3 to step S5 are as follows:

[0015] S31: Use the platform crane to lift one end of the limiting rigging pre-arranged on the platform anchor winch deck and slowly transfer it to the tugboat deck;

[0016] S32: The tugboat’s main towing cable is connected to the limiting rigging, the crane connection is released and the crane is recovered to the platform;

[0017] S33: The tugboat slowly moves away from the platform and pays out the main towline to an appropriate length.

[0018] Preferably in the present technical solution, the suitable length range in step S33 is 200-400 meters.

[0019] Preferably in the present technical solution, in the step S1, the platform limit towing points are welded on the four columns of the semi-submersible production platform in advance, and the safe working load of the support point structure design must meet the platform limit requirements.

[0020] Preferably in the present technical solution, the limiting main rigging and the limiting emergency rigging have the same structure, and the rigging consists of a wire rope rigging, a shackle, and a wire rope ring. One end of the limiting rigging is connected to the limiting support point of the semi-submersible production platform, and the other end is tied and fixed to the platform anchor machine deck.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The method for converting the towing and limiting modes of a semi-submersible production platform can realize the safe and efficient seamless conversion of the semi-submersible production platform from the towing mode to the limiting mode, thereby ensuring the smooth implementation of subsequent reconnection and installation operations of the semi-submersible production platform. At the same time, the method of the invention can greatly save the operating time for converting the towing and limiting modes of the semi-submersible production platform, and can complete the reconnection of the platform mooring system within the shortest weather window to ensure the safety of the semi-submersible production platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the overall arrangement diagram of the limiting rigging of the semi-submersible production platform in the present invention;

[0024] Figure 2 It is a schematic diagram of the limit towing point welded on the platform column in the present invention;

[0025] Figure 3 This is a typical schematic diagram of the towing of a semi-submersible production platform in the present invention;

[0026] Figure 4-Figure 7 This is a typical schematic diagram of the towing of a semi-submersible production platform in the present invention;

[0027] Figure 8-Figure 11 It is a schematic diagram of the tugboat position adjustment during the conversion between the platform towing and limiting modes in the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that, in the description of the present invention, the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0030] Furthermore, it should be understood that for the sake of ease of description, the sizes of the various components shown in the drawings are not drawn according to actual proportions. For example, the thickness or width of certain layers may be exaggerated relative to other layers.

[0031] It should be noted that like reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined or described in one drawing, it will not require further detailed discussion and description in the description of the subsequent drawings.

[0032] The purpose of the present invention is to provide a method for converting the towing and limiting modes of a semi-submersible production platform, and according to the characteristics of wet towing and limiting of the semi-submersible production platform, the semi-submersible production platform is seamlessly converted from the wet towing mode to the limiting mode. To this end, the present invention provides a technical solution: a method for converting the towing and limiting modes of a semi-submersible production platform, and the operating steps are as follows:

[0033] S1: Figure 1-2 As shown, before the semi-submersible production platform is towed, the platform towing rigging and limiting rigging are installed on the platform in advance and tied and fixed;

[0034] S2: Figure 3 As shown, this embodiment provides a typical towing technical solution for a semi-submersible production platform. The semi-submersible production platform is towed by three tugboats (main towing tugboat 1, towing tugboat 2 and towing tugboat 3) to the oil and gas field site, and the platform begins to ballast and adjusts the platform from the towing draft to the limit draft;

[0035] S3: Figure 8 As shown, the limiting tugboat 1 travels to the predetermined position, which is set to the northeast side of the platform, and its stern is about 15-20 meters away from the semi-submerged platform. The platform and the tugboat cooperate to transfer and connect the first platform limiting rigging, wherein the steps of transferring and connecting the platform limiting rigging are as follows:

[0036] S31: Figure 4 and Figure 5 As shown, the platform crane is used to lift one end of the limiting rigging pre-arranged on the platform anchor machine deck and slowly transfer it to the tugboat deck;

[0037] S32: Figure 6 As shown, the tugboat main towing cable is connected to the limiting rigging, the crane connection is released and the crane is recovered to the platform;

[0038] S33: Figure 7 As shown, the tugboat slowly leaves the platform and releases the main towline to a suitable length, the suitable length range is 200-400 meters, and the length selected in this embodiment is 300 meters;

[0039] S4: Figure 3 and Fig. 9 As shown, the tugboat 2 on the northeast side of the platform is released, and the tugboat 2 travels to the northwest side of the platform. The platform and the tugboat cooperate to transfer and connect the second platform limiting rigging, and the tugboat 2 is converted into a limiting tugboat;

[0040] S5: Figure 3 and Fig.10 As shown, the towing tugboat 3 on the southeast side of the platform is released, and the platform and the tugboat cooperate to transfer and connect the third platform limiting rigging, and the towing tugboat 3 is converted into a limiting tugboat;

[0041] S6: Figure 3 and Fig.11 As shown, the main towing tugboat 1 on the east side of the platform is released, and the towing tugboat 1 travels to the southwest side of the platform. The platform and the tugboat cooperate to transfer and connect the fourth platform limiting rigging, and the main towing tugboat 1 is converted into a limiting tugboat;

[0042] S7: The semi-submersible platform is tested for position limiting by four position limiting tugboats. If the test meets the requirements, the subsequent mooring system can be connected back.

[0043] It should be noted that the limiting rigging in this embodiment includes limiting main rigging and limiting emergency rigging. The structures of the limiting main rigging and the limiting emergency rigging are consistent. The rigging is composed of wire rope rigging, shackles, and wire rope rings. One end of the limiting rigging is connected to the limiting supporting point of the semi-submersible production platform, and the other end is tied and fixed to the platform anchor machine deck. Before implementation, it is necessary to weld the platform limiting towing points on the four columns of the semi-submersible production platform in advance, and the safe working load of the supporting point structure design must meet the platform limiting requirements.

[0044] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for converting a semi-submersible production platform to towing and limiting modes, characterized in that: The operation steps are as follows: S1: Before towing the semi-submersible production platform, install the platform towing rigging and limit rigging on the platform in advance and tie them up and fix them; S2: The semi-submersible production platform is towed to the oil and gas field site by three tugboats, and the platform begins to be ballasted, adjusting the platform from the towing draft to the limited draft; S3: Towing tugboat 2 drives to the predetermined position, which is set to the northeast side of the platform. The stern of towing tugboat 2 is controlled to be about 15-20 meters away from the platform. The platform and towing tugboat 2 cooperate to transfer and connect the first platform limiting rigging; S4: The tugboat 2 on the northeast side of the platform is released, and the tugboat 2 travels to the northwest side of the platform. The platform and the tugboat cooperate to transfer and connect the second platform limiting rigging, and the tugboat 2 is converted into a limiting tugboat; S5: The tugboat 3 on the southeast side of the platform is released, and the platform and the tugboat cooperate to transfer and connect the third platform limiting rigging, and the tugboat 3 is converted into a limiting tugboat; S6: The main tugboat 1 on the east side of the platform is released, and the main tugboat 1 travels to the southwest side of the platform. The platform and the tugboat cooperate to transfer and connect the fourth platform limiting rigging, and the main tugboat 1 is converted into a limiting tugboat; S7: The semi-submersible production platform is tested for position limiting by using four position limiting tugboats. If the test meets the requirements, the subsequent mooring system can be connected back.

2. The method for converting the towing and limiting modes of a semi-submersible production platform according to claim 1 is characterized in that: The position-limiting rigging in step S1 includes the position-limiting main rigging and the position-limiting emergency rigging.

3. The method for converting the towing and limiting modes of a semi-submersible production platform according to claim 1 is characterized in that: The steps of transferring and connecting the platform limiting rigging from step S3 to step S5 are as follows: S31: Use the platform crane to lift one end of the limiting rigging pre-arranged on the platform anchor winch deck and slowly transfer it to the tugboat deck; S32: The tugboat’s main towing cable is connected to the limiting rigging, the crane connection is released and the crane is recovered to the platform; S33: The tugboat slowly moves away from the platform and pays out the main towline to an appropriate length.

4. The method for converting the towing and limiting modes of a semi-submersible production platform according to claim 3 is characterized in that: The suitable length range in step S33 is 200-400 meters.

5. The method for converting the towing and limiting modes of a semi-submersible production platform according to claim 1 is characterized in that: In step S1, platform limit towing points are welded on the four columns of the semi-submersible production platform in advance, and the safe working load of the support point structure design must meet the platform limit requirements.

6. The method for converting the towing and limiting modes of a semi-submersible production platform according to claim 2 is characterized in that: The limiting main rigging and the limiting emergency rigging have the same structure. The rigging consists of a wire rope rigging, a shackle, and a wire rope ring. One end of the limiting rigging is connected to the limiting support point of the semi-submersible production platform, and the other end is tied and fixed to the platform anchor machine deck.

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