Top hydraulic tensioning type drilling riser system suitable for cylindrical floating deepwater dry-type platform

Abstract

The invention discloses a top hydraulic tensioning type drilling riser system suitable for a cylindrical floating deepwater dry platform, which comprises a production riser system, a tensioning system, a wellhead connecting system and an underwater isolation barrier system, the production riser system comprises a flow divider, a telescopic joint, an overwater blowout preventer, a platform moon pool structure and a single drilling riser, the single drilling riser is of a hollow tubular structure, the flow divider, the telescopic joint, the overwater blowout preventer, the tensioning system, the platform moon pool structure and the top of the single drilling riser are sequentially connected, and the bottom of the single drilling riser is connected with an underwater wellhead through the wellhead connecting system and the underwater isolation barrier system. Based on an overwater blowout preventer mode, a huge, overweight and high-cost underwater blowout preventer does not need to be used, then the deepwater drilling operation cost is reduced, and through combined use of the overwater blowout preventer and the underwater isolation barrier system, the drilling operation safety is effectively improved, and the operation risk is reduced.

Description

Technical Field

[0001] This invention relates to the field of deep-sea drilling technology, and in particular to a top hydraulic tensioning drilling riser system suitable for cylindrical floating deep-sea dry platforms. Background Technology

[0002] As oil and gas exploration and development gradually moves towards deepwater / ultra-deepwater formations, conventional deepwater oil and gas fields utilize semi-submersible drilling platforms with subsea blowout preventers (FOPs) for drilling. Production is achieved through subsea wellheads and production trees, with oil, gas, and water treatment and storage carried out on floating production platforms via SCR (Silicon Controlled Reduction) systems. Alternatively, oil and gas can be transported to shallow water platforms for processing via subsea pipelines. Deepwater development models often employ semi-submersible drilling platforms, FPSOs (Floating Production Stations), subsea wellheads, and production trees. Due to the use of subsea blowout preventers for drilling and subsea wet production trees for production, the overall development costs are high, and there are high requirements for the reservoir characteristics and production capacity of the oil and gas field.

[0003] In recent years, marginal oilfields have been continuously discovered in deepwater exploration in China. Conventional deepwater oil and gas field development models generally adopt drilling methods based on blowout preventers (BOPs) and subsea wet production trees, which are costly and cannot achieve economic production targets, thus limiting the development of deepwater oil and gas fields. Cylindrical floating deepwater dry platforms can integrate drilling, production, storage, and offloading functions. Using surface BOPs and water-to-water dry production trees can effectively reduce costs. During drilling operations, the extreme motion of the cylindrical floating deepwater dry platform, such as platform movement and offset, along with the well control challenges posed by the absence of subsea BOPs, places extremely high technical demands on the drilling riser system connecting the subsea wellhead and the platform.

[0004] Therefore, there is an urgent need for a top hydraulic tensioning drilling riser system suitable for cylindrical floating deep-water dry platforms. Summary of the Invention

[0005] This invention provides a top hydraulic tensioning drilling riser system suitable for cylindrical floating deepwater dry platforms. Based on the surface blowout preventer (BOP) model, it eliminates the need for bulky, heavy, and costly subsea BOPs, thereby reducing the cost of deepwater drilling operations. Furthermore, the combined use of the surface BOP and the subsea isolation barrier system effectively increases drilling operation safety and reduces operational risks.

[0006] This invention provides a top hydraulic tensioning drilling riser system suitable for cylindrical floating deep-water dry platforms, comprising a production riser system, a tensioning system, a wellhead connection system, and a subsea isolation barrier system. The production riser system includes a distributor, an expansion joint, a surface blowout preventer, a platform moon pool structure, and a single drilling riser. The single drilling riser is a hollow tubular structure. The distributor, the expansion joint, the surface blowout preventer, the tensioning system, the platform moon pool structure, and the top of the single drilling riser are connected in sequence. The bottom of the single drilling riser is connected to the subsea wellhead through the wellhead connection system and the subsea isolation barrier system.

[0007] The top hydraulic tensioning drilling riser system applicable to cylindrical floating deep-water dry platforms, preferably, includes an expansion joint comprising an inner cylinder and an outer cylinder, the outer cylinder being sleeved outside the inner cylinder to achieve a vertical sliding connection between the two, the inner cylinder being connected to the distributor, and the outer cylinder being connected to the surface blowout preventer.

[0008] The aforementioned top hydraulic tensioning drilling riser system suitable for cylindrical floating deep-water dry platforms preferably includes a tensioning sub, a tensioning ring, and a hydraulic-pneumatic tensioning mechanism. The tensioning sub is a hollow, thick-walled tubular structure. The tensioning ring is sleeved on the outside of the tensioning sub and connected to the hydraulic-pneumatic tensioning mechanism. The lower end of the tensioning sub is connected to the platform's moon pool structure, and the upper end is connected to the surface blowout preventer. The hydraulic-pneumatic tensioning mechanism provides upward tension to the entire production riser system by thrusting the tensioning ring.

[0009] The top hydraulic tensioning drilling riser system applicable to cylindrical floating deep-water dry platforms, preferably, includes a hydraulic pneumatic tensioning mechanism comprising a hydraulic cylinder and an accumulator. The hydraulic cylinder includes a cylinder seat and a piston rod. The cylinder seat is connected to the cylindrical floating deep-water dry platform, and the piston rod is connected to the tensioning ring. The hydraulic cylinder is mirror-displayed around the tensioning ring, and the accumulator is mounted on the hydraulic cylinder to provide power to the hydraulic cylinder.

[0010] The top hydraulic tensioning drilling riser system applicable to cylindrical floating deep-water dry platforms, preferably, includes a platform moon pool structure comprising a single moon pool section, a single keel section, and a centering device. The single moon pool section and the single keel section are hollow tubular structures. The single keel section is located at the bottom end of the single moon pool section and at the platform keel. The single moon pool section is connected to the tensioning subsection, and the single keel section is connected to the single drilling riser. The centering device is respectively installed outside the single keel section and the single moon pool section. The centering device is used to keep the single keel section and the single moon pool section in the middle position of the moon pool.

[0011] The top hydraulic tensioning drilling riser system applicable to cylindrical floating deep-water dry platforms, preferably, has a keel that is a symmetrical conical tube that is thicker in the middle and thinner at both ends.

[0012] The top hydraulic tensioning drilling riser system applicable to cylindrical floating deep-water dry platforms, preferably, includes an underwater conical stress sub and a reconnector in the wellhead connection system. The underwater conical stress sub is a hollow, tapered tubular structure connected to the bottom of a single drilling riser. The conical stress sub is connected to the underwater isolation barrier system via the reconnector.

[0013] The aforementioned top hydraulic tensioning drilling riser system for cylindrical floating deep-water dry platforms, preferably, includes an underwater isolation barrier system comprising a riser reconnector, a shear seal gate, a pipe gate, a wellhead connector, and an underwater control system. The shear seal gate is positioned above the pipe gate, with its bottom end connected to the underwater wellhead via the wellhead connector. The top end of the shear seal gate is connected to the underwater conical stress-reducing section via an inverted riser reconnector. The riser reconnector, shear seal gate, pipe gate, and wellhead connector are all connected to the underwater control system. In the event of a typhoon, riser leakage, or other extreme conditions, the underwater control system rapidly closes the shear seal gate and the pipe gate, thereby sealing the underwater wellhead at the seabed. The high-pressure drilling riser is released by opening the inverted riser reconnector, effectively ensuring wellbore safety.

[0014] The beneficial effects are: The cylindrical floating deepwater dry platform drilling riser system of this invention, through special configurations such as an underwater isolation barrier system, a moon pool unit and its centering device, and a keel unit and its centering device, and in conjunction with important riser system equipment such as expansion joints, surface blowout preventers, hydraulic and pneumatic tensioners, and underwater conical stress short sections, can effectively ensure that the cylindrical floating deepwater dry platform can use surface blowout preventers for deepwater drilling operations without the need for bulky, heavy, and costly subsea blowout preventers, thereby reducing the cost of deepwater drilling operations. Furthermore, the combined use of surface blowout preventers and underwater isolation barrier systems effectively increases drilling operation safety. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 A schematic diagram of the specific structure of the underwater isolation barrier system; Figure 3 A schematic diagram of the specific structure of a single root of the moon pool and its centering device; Figure 4This is a schematic diagram of the specific structure of a single keel and its centering device.

[0016] In the picture: 1. Well shaft; 2. Submersible wellhead; 3. Underwater isolation barrier system; 3-1. Riser reconnection connector; 3-2. Shearing full-sealing gate; 3-3. Pipe gate; 3-4. Wellhead connector; 3-5. Underwater control system; 3-6. Rising flange; 3-7. Reducing flange; 4. Reconnect the connector; 5. Underwater tapered stress-reducing sub; 6. Single drill riser; 7. Single keel; 8. Single moon pool; 9. Centering device; 10. Tensioning sub; 11. Tensioning ring; 12. Hydraulic / pneumatic tensioner; 13. Floating blowout preventer; 14. Expansion joint; 6. Cylindrical floating deep-water dry platform. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0018] In the description of this invention, it should be noted that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the system or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] This invention provides a top-hydraulic tensioned drilling riser system suitable for cylindrical floating deepwater dry platforms, comprising a production riser system, a tensioning system, a wellhead connection system, and a subsea isolation barrier system. The production riser system includes a distributor, an expansion joint, a surface blowout preventer (BOP), a platform moon pool structure, and a single drilling riser. The single drilling riser is a hollow tubular structure. The distributor, expansion joint, surface BOP, tensioning system, platform moon pool structure, and the top of the single drilling riser are sequentially connected. The bottom of the single drilling riser is connected to the subsea wellhead via the wellhead connection system and the subsea isolation barrier system. This invention, based on the surface BOP model, eliminates the need for bulky, heavy, and costly subsea BOPs, thereby reducing the cost of deepwater drilling operations. Furthermore, the combined use of the surface BOP and the subsea isolation barrier system effectively increases drilling operation safety and reduces operational risks.

[0021] The following section uses a top hydraulic tensioning drilling riser system suitable for cylindrical floating deep-water dry platforms as an example to illustrate the entire technical process in detail.

[0022] Reference Figures 1 to 4 The invention relates to a top hydraulic tensioning drilling riser system suitable for cylindrical floating deep-water dry platforms, characterized in that it includes a production riser system, a tensioning system, a wellhead connection system, and an underwater isolation barrier system 3. The production riser system includes a distributor, an expansion joint 14, a surface blowout preventer 13, a platform moon pool structure, and a single drilling riser 6. The single drilling riser 6 is a hollow tubular structure. The distributor, expansion joint 14, surface blowout preventer 13, tensioning system, platform moon pool structure, and the top of the single drilling riser 6 are connected in sequence. The bottom of the single drilling riser 6 is connected to the underwater wellhead 2 through the wellhead connection system and the underwater isolation barrier system 3.

[0023] Among them, the surface blowout preventer 13 is mainly used to provide well control for the drilling system. In case of emergency such as blowout, it can realize the emergency shut-in and well control function so that the staff can carry out emergency operations.

[0024] The expansion joint 14 includes an inner cylinder and an outer cylinder. The outer cylinder is sleeved outside the inner cylinder to achieve a vertical sliding connection between the two. The inner cylinder is connected to the diverter, and the outer cylinder is connected to the surface blowout preventer 13.

[0025] In actual operation, when the pipeline in the sea experiences heave, the expansion joint 14 can provide passive compensation, improving the system's operational stability. Regarding horizontal deviation, in deep water, the drilling riser system is relatively long. During horizontal deviation, a single riser 6 can deform to mitigate the effects of the deviation. By cooperating with the expansion joint 14, it achieves heave compensation, adapting to the special motion responses of the cylindrical floating deep-water dry platform 16, including large operating water depths, significant horizontal deviations, and heave movements.

[0026] Continue to refer to Figure 1 The tensioning system includes a tensioning sub 10, a tensioning ring 11, and a hydraulic-pneumatic tensioning mechanism 12. The tensioning sub 10 is a hollow, thick-walled tubular structure. The tensioning ring 11 is sleeved on the outside of the tensioning sub 10 and is connected to the hydraulic-pneumatic tensioning mechanism 12. The lower end of the tensioning sub 10 is connected to the platform moon pool structure, and the upper end of the tensioning sub 10 is connected to the surface blowout preventer 13. The hydraulic-pneumatic tensioning mechanism 12 provides upward tension to the entire production riser system by pulling the tensioning ring 11 with thrust.

[0027] Among them, the tensioning ring 11 is mainly used to provide upward tension to the drilling riser system and its tensioning sub 9. The tensioning ring 11 is a ring-shaped component. The inside of the tensioning ring 11 is threadedly connected to the tensioning sub 10 and can be rotated up and down to achieve fine adjustment of different tension positions of the drilling riser tensioning sub 9.

[0028] The hydraulic-pneumatic tensioning mechanism 12 includes a hydraulic cylinder and an accumulator. The hydraulic cylinder includes a cylinder seat and a piston rod. The cylinder seat is connected to the cylindrical floating deep-water dry platform 16, and the piston rod is connected to the tensioning ring 11. The hydraulic cylinder is mirror-mounted around the tensioning ring 11. The accumulator is mounted on the hydraulic cylinder to provide power. By controlling the accumulator pressure, different hydraulic cylinder pressures can be adjusted, thereby providing different tensions to the drilling riser system. Preferably, there are four hydraulic cylinders and four accumulators.

[0029] refer to Figure 1 , Figure 3 and Figure 4 The platform moon pool structure includes a single moon pool section 8, a single keel section 7, and a centering device 9. The single moon pool section 8 and the single keel section 7 are hollow tubular structures. The single keel section 7 is located at the bottom end of the single moon pool section 8 and at the platform keel, bearing the extreme bending moment generated during the transition of the riser from the moon pool to the water. The single moon pool section 8 is connected to the tensioning short section 10, and the single keel section 7 is connected to the drilling riser section 6. Centering devices 9 are respectively installed on the outside of the single keel section 7 and the single moon pool section 8, and are used to maintain the single keel section 7 and the single moon pool section 8 in the middle position within the moon pool.

[0030] Among them, the centering device 9 is made of metal or non-metal, which realizes the centering and straightening of the single keel 7 and the single moon pool 8, and reduces the friction of the short section and the guide structure.

[0031] Continue to refer to Figure 1 and Figure 4 The keel 7 is a symmetrical conical tube that is thicker in the middle and thinner at both ends. A set of centering devices 9 is set on the outer side of the middle of the keel 7. The centering devices 9 are used to keep the keel 7 in the middle position of the moon pool and can slide vertically relative to the platform moon pool.

[0032] Continue to refer to Figure 3 Multiple sets of centering devices 9 are provided on the outside of the single moon pool tube 8. The centering devices are used to keep the single moon pool tube in the middle position of the moon pool and can slide vertically relative to the platform moon pool to realize the centering and straightening of the riser at the moon pool well slot.

[0033] Continue to refer to Figure 1 To further address the high stress caused by high bending moments at the connection points between the drilling riser system and the subsea wellhead and underwater isolation barrier system on the seabed, the wellhead connection system includes an underwater conical stress-reducing section 5 and a reconnector 4. The underwater conical stress-reducing section 5 is a hollow, tapered tubular structure connected to the bottom of the drilling riser 6. The conical stress-reducing section is connected to the underwater isolation barrier system 3 via the reconnector 4.

[0034] The underwater conical stress-reinforced sub-section 5 is connected to the underwater isolation barrier system 3 via the reconnector 4. The underwater conical stress-reinforced sub-section 5, through its conical interface design, can withstand extreme bending moments and facilitates the transition from the drilling riser to the underwater wellhead on the seabed.

[0035] Continue to refer to Figure 1 and Figure 2 To further enhance the safety of the drilling riser system and reduce operational risks under typhoon riser leakage or other extreme conditions, an underwater isolation barrier system 3 is installed above the subsea wellhead 2. If the drilling riser system is equipped with a separate surface blowout preventer, the underwater drilling riser will be the weakest point in the entire system; any damage to the integrity of the drilling riser will pose unacceptable risks. By adding the underwater isolation barrier system 3 to the subsea wellhead, in the event of a typhoon, riser leakage, or other extreme conditions, the underwater control system 3-5 can quickly close the shear gate 3-2 and the pipe gate 3-3, thereby sealing the subsea wellhead at the seabed. The high-pressure drilling riser can then be released by opening the inverted riser reconnection connector 3-1, effectively ensuring wellbore safety and reducing operational risks.

[0036] The underwater isolation barrier system 3 includes multiple pipe sections, a riser reconnector 3-1, a shear gate 3-2, a pipe gate 3-3, a wellhead connector 3-4, and an underwater control system 3-5. The pipes are connected to each other via a riser flange 3-6. The pipes are connected to the wellhead connector 3-4 via a reducing flange 3-7. The wellhead connector 3-4 is connected to the underwater wellhead 2. The shear gate 3-2 and the pipe gate 3-3 are located at the pipe interfaces, with the shear gate 3-2 positioned above the pipe gate 3-3. The pipe at the top of the shear gate 3-2 is connected to the underwater tapered stress joint 5 via an inverted riser reconnector 3-1. The pipe reconnector 3-1, the shear gate 3-2, the pipe gate 3-3, and the wellhead connector 3-4 are all connected to the underwater control system 3-5.

[0037] Among them, the underwater control system 3-5 is a hydraulic control system, which can realize remote sonar control.

[0038] Work process: The production riser system, tensioning system, wellhead connection system, and underwater isolation barrier system 3 connect the subsea wellbore 1 and the cylindrical floating deep-water dry platform 16 to form a drilling channel, through which drill pipes and drilling fluids can be used to drill and exploit subsea oil and gas resources.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A top hydraulic tensioning drilling riser system suitable for cylindrical floating deep-water dry platforms, characterized in that, The system includes a production riser system, a tensioning system, a wellhead connection system, and a subsea isolation barrier system. The production riser system includes a distributor, an expansion joint, a surface blowout preventer, a platform moon pool structure, and a single drilling riser. The single drilling riser is a hollow tubular structure. The distributor, the expansion joint, the surface blowout preventer, the tensioning system, the platform moon pool structure, and the top of the single drilling riser are connected in sequence. The bottom of the single drilling riser is connected to the subsea wellhead through the wellhead connection system and the subsea isolation barrier system.

2. The top hydraulic tensioning drilling riser system for cylindrical floating deep-water dry platforms according to claim 1, characterized in that, The expansion joint includes an inner cylinder and an outer cylinder. The outer cylinder is sleeved outside the inner cylinder to achieve a vertical sliding connection between the two. The inner cylinder is connected to the diverter, and the outer cylinder is connected to the surface blowout preventer.

3. The top hydraulic tensioning drilling riser system for cylindrical floating deep-water dry platforms according to claim 2, characterized in that, The tensioning system includes a tensioning section, a tensioning ring, and a hydraulic-pneumatic tensioning mechanism. The tensioning section is a hollow, thick-walled tubular structure. The tensioning ring is sleeved on the outside of the tensioning section and is connected to the hydraulic-pneumatic tensioning mechanism. The lower end of the tensioning section is connected to the platform moon pool structure, and the upper end of the tensioning section is connected to the surface blowout preventer. The hydraulic-pneumatic tensioning mechanism provides upward tension to the entire production riser system by pulling the tensioning ring with thrust.

4. The top hydraulic tensioning drilling riser system for cylindrical floating deep-water dry platforms according to claim 3, characterized in that, The hydraulic-pneumatic tensioning mechanism includes a hydraulic cylinder and an accumulator. The hydraulic cylinder includes a cylinder seat and a piston rod. The cylinder seat is connected to a cylindrical floating deep-water dry platform. The piston rod is connected to the tensioning ring. The hydraulic cylinder is mirror-arranged around the tensioning ring. The accumulator is mounted on the hydraulic cylinder to provide power to the hydraulic cylinder.

5. The top hydraulic tensioning drilling riser system for cylindrical floating deep-water dry platforms according to claim 4, characterized in that, The platform moon pool structure includes a single moon pool section, a single keel section, and a centering device. The single moon pool section and the single keel section are hollow tubular structures. The single keel section is located at the bottom end of the single moon pool section and at the platform keel. The single moon pool section is connected to the tensioning short section, and the single keel section is connected to the drilling riser section. The centering device is respectively installed on the outside of the single keel section and the single moon pool section. The centering device is used to keep the single keel section and the single moon pool section in the middle position of the moon pool.

6. The top hydraulic tensioning drilling riser system for cylindrical floating deep-water dry platforms according to claim 5, characterized in that, The keel is a symmetrical conical tube that is thicker in the middle and thinner at both ends.

7. The top hydraulic tensioning drilling riser system for cylindrical floating deepwater dry platforms according to claim 6, characterized in that, The wellhead connection system includes an underwater conical stress sub and a reconnector. The underwater conical stress sub is a hollow, tapered tubular structure. The underwater conical stress sub is connected to the bottom of a single drilling riser. The conical stress sub is connected to the underwater isolation barrier system through the reconnector.

8. The top hydraulic tensioning drilling riser system for cylindrical floating deepwater dry platforms according to claim 7, characterized in that, The underwater isolation barrier system includes a riser reconnector, a shear seal gate, a pipe gate, a wellhead connector, and an underwater control system. The shear seal gate is positioned above the pipe gate, and the bottom end of the pipe gate is connected to the underwater wellhead via the wellhead connector. The top end of the shear seal gate is connected to the underwater conical stress-relief section via the inverted riser reconnector. The riser reconnector, the shear seal gate, the pipe gate, and the wellhead connector are all connected to the underwater control system. In the event of a typhoon, riser leakage, or other extreme conditions, the underwater control system quickly closes the shear seal gate and the pipe gate, thereby sealing the underwater wellhead at the seabed. The high-pressure drilling riser is released by opening the inverted riser reconnector, effectively ensuring wellbore safety.

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