A pressure control drilling system and drilling method for deepwater drilling in deep sea areas

Abstract

The present invention provides a pressure control drilling system and a drilling method for deepwater drilling in deep sea areas. The system includes a riser rotation control sub, an MPD hydraulic control sub, a riser annulus sealing device, a riser four-way joint, etc., which are integrated on an independent drilling riser joint. It forms a system with its corresponding key surface equipment: MPD choke manifolds, MPD hydraulic control manifolds, MPD buffer manifolds, MPD filter manifolds, MPD mud-gas separators, etc., and is used in conjunction with equipment such as riser boost pumps, metering tank pumps, rotary tables, mud diverters, riser telescopic joints, riser tension rings, drilling risers, subsea blowout preventer stacks, subsea wellheads, etc. of conventional deepwater drilling equipment. The present invention can be applied to carry out pressure control drilling and related drilling operations on equipment such as semi-submersible drilling platforms and drill ships in deep water (water depth above 300m).

Description

Technical Field

[0001] The present invention belongs to the technical field of deep - sea drilling, and particularly relates to a pressure - controlled drilling system and a drilling method for deep - water drilling in deep - sea areas. Background Art

[0002] In oil drilling engineering, to overcome the technical problem of the narrow mud density window when drilling through abnormal formation pressures, the research and application of land Managed Pressure Drilling (MPD) equipment and related process technologies have developed rapidly since the research began in 2008. It has been continuously promoted and applied in oilfields such as Xinjiang, Sichuan, Changqing Oilfield, and Liaohe Oilfield. Currently, it has been applied in offshore oilfields in the Bohai Sea, and in the surrounding waters of Zhanjiang, MPD has also been applied in shallow - water oilfields. The MPD process on a jack - up drilling platform in a shallow - water oilfield has no major differences from that on land. It can be implemented and applied by installing it above the blowout preventer at the wellhead according to the requirements of the jack - up platform project. However, when applying MPD technology on a deep - water drilling rig (usually drilling in waters with a water depth of 300 m or more than 500 m, known as deep - water drilling; the drilling rig usually uses a semi - submersible drilling platform or a drillship), new challenges will be faced.

[0003] The strata in the South China Sea are a world - famous high - temperature and high - pressure area. Especially in recent years, with the discovery of multiple deep - water gas fields such as Lingshui 17 - 2 (LW17 - 2) in the South China Sea, in the deep - water area of the South China Sea, whether it is exploration or development drilling, there is a great demand for MPD. However, since the blowout preventer in deep - water drilling is placed on the seabed, the low pressure borne by the mud diverter and the telescopic riser near the wellhead of the drilling platform cannot meet the requirements of MPD, and it is even more impossible to install and use the MPD equipment of the existing jack - up drilling platform.

[0004] Therefore, in the face of the problem of high drilling service fees for foreign technologies and the cost of oilfield exploration and development, it is necessary to develop an independent riser pressure - controlled drilling system in China that meets the needs of deep - water drilling in the South China Sea and overseas in the area below the mud diverter and the drilling telescopic riser and above the top of the deep - water riser near the platform moonpool during deep - water drilling operations. Summary of the Invention

[0005] The purpose of the present invention is to solve the defects existing in the above - mentioned prior art, and provide a pressure - controlled drilling system and a drilling method for deep - water drilling in deep - sea areas.

[0006] The present invention adopts the following technical solutions:

[0007] The present invention provides a pressure control drilling system for deep - water drilling in deep - sea areas, including a rotary table, a mud diverter, a riser slip joint, a riser booster pump, a riser tension ring, a metering tank pump, a riser rotation control sub - section, an MPD hydraulic control sub - section, a riser annulus sealing device, a riser four - way joint, a drilling riser, an underwater blowout preventer stack, and a subsea wellhead.

[0008] The mud diverter is installed on the lower side of the rotary table. The mud diverter is connected to the metering tank, the MPD buffer manifold, the MPD filter manifold, and the mud shaker respectively through pipeline Ⅰ; the mud diverter is connected to the metering tank pump through pipeline Ⅱ, and the metering tank pump is connected to the metering tank.

[0009] The first section of the riser is installed at the lower end of the mud diverter; the riser slip joint is installed at the connection between the first section of the riser and the second section of the riser, and the lower end of the riser tension ring is installed on the second section of the riser; the riser rotation control sub - section is installed at the lower end of the second section of the riser. The riser rotation control sub - section is connected to the MPD buffer manifold through pipeline Ⅳ. The MPD hydraulic control sub - section is installed at the lower end of the riser rotation control sub - section. The riser annulus sealing device is installed on the lower side of the MPD hydraulic control sub - section. The riser four - way joint is installed on the lower side of the riser annulus sealing device. The riser four - way joint is connected to the MPD buffer manifold through pipeline Ⅵ and pipeline Ⅶ.

[0010] The riser booster pump is connected to the MPD buffer manifold through pipeline Ⅲ, and the lower end of the riser booster pump's pressurization pipeline is connected to the underwater blowout preventer stack.

[0011] The MPD hydraulic control sub - section is connected to the MPD hydraulic control manifold through the riser accessory pipeline;

[0012] The drilling riser is installed on the lower side of the riser four - way joint. The underwater blowout preventer stack is installed on the lower side of the drilling riser. The underwater blowout preventer stack is connected to the rig choke manifold through the choke line and the kill line.

[0013] The subsea wellhead is installed on the lower side of the underwater blowout preventer stack.

[0014] The MPD buffer manifold is connected to the MPD filter manifold through pipeline Ⅷ, and the MPD buffer manifold is connected to the MPD choke manifold and the MPD mud - gas separator respectively through pipeline Ⅸ; the MPD buffer manifold is connected to the rig choke manifold through pipeline Ⅹ; the MPD filter manifold is connected to the MPD choke manifold through pipeline Ⅺ. The mud shaker is connected to the MPD mud - gas separator and the rig mud - gas separator respectively through pipeline Ⅻ. Both the MPD mud - gas separator and the rig mud - gas separator have exhaust ports. The rig choke manifold is connected to the rig mud - gas separator through pipeline ⅰ; the MPD choke manifold is connected to the MPD mud - gas separator.

[0015] Furthermore, the MPD hydraulic control sub is an integrated electro-hydraulic control device for the riser rotation control sub and the riser annulus sealing device. The cables of the device communicate with the platform equipment through the riser accessory pipeline channel and perform functions such as receiving control instructions.

[0016] Furthermore, the MPD buffer manifold is equipped with a 5.171 MPa riser pressure relief valve, a 5.516 MPa riser rupture disk, and a 34.475 MPa riser boost pipeline pressure relief valve to protect the riser and its accessory pipelines.

[0017] Furthermore, the MPD filter manifold is used to filter out larger mud cuttings to prevent clogging of the MPD choke manifold.

[0018] A drilling method for a managed pressure drilling system in deep-sea waters includes:

[0019] Mode A. Deepwater managed pressure drilling:

[0020] Step 1. Install the deepwater managed pressure drilling integrated device and all related equipment into the semi-submersible drilling rig equipment process and commission it to normal.

[0021] Step 2. Start the managed pressure drilling operation procedure, open the working valve of the riser rotation control sub, apply backpressure by circulating mud through the MPD choke manifold, transfer the pressure to the bottom of the well through the riser annulus, and keep the hydrostatic pressure greater than the formation pressure with a certain accuracy using slightly overbalanced drilling.

[0022] Step 3. When encountering high formation pressure, quickly adjust the choke pressure without adjusting the mud density to ensure the safety of the drilling operation.

[0023] Mode B. Deepwater managed pressure mud cap drilling (PMCD):

[0024] Step 1. Before the drilling operation starts, fill the deepwater kill line with base oil.

[0025] Step 2. Drill the well in the MPD mode with an acceptable loss rate.

[0026] Step 3. When a large amount of loss occurs, close the subsea BOP blowout preventer.

[0027] Step 4. Use the kill line to determine the reservoir pressure or formation fracture pressure by adding the hydrostatic pressure of the mud column below the BOP and the static pressure of the kill line.

[0028] Step 5. Gradually lower the mud column level in the riser until it is just less than the formation fracture pressure of the formation being drilled.

[0029] Step 6. Continue to drill using the PMCD mode. Fill the riser with seawater from the upper part of the riser to maintain the well pressure balance.

[0030] Mode C. Normal drilling mode:

[0031] Step 1. Close all circulation valves and various electrical appliances of the managed pressure drilling surface equipment and stop operation.

[0032] Step 2. Remove the rotary seal assembly from the riser rotary control sub.

[0033] Step 3. The riser annulus seal device passage is in the open state (non-sealed state).

[0034] Step 4. The wellbore fluid column pressure is greater than the formation pressure, which belongs to overbalanced drilling.

[0035] Advantages of the present invention:

[0036] 1. Deepwater drilling places higher requirements on the platform's MPD equipment. To ensure the safety of the riser and the drilling platform operation, before the mud returning from the well enters the MPD choke manifold, an MPD buffer manifold and an MPD filtration manifold are added.

[0037] The buffer manifold is a buffer and distribution unit for mud, and is also equipped with a 5.171 MPa (750 psi) riser pressure relief valve and a 5.516 MPa (5000 psi) riser boost line pressure relief valve to protect the riser and other accessory pipelines.

[0038] The filtration manifold is mainly used to filter out larger cuttings to prevent the mud cuttings from clogging the MPD choke manifold.

[0039] MPD choke manifold: Its function is similar to that of a shallow water jack-up platform or onshore MPD. It consists of control and metering units, and is equipped with automatic and manual throttle valves, an intelligent control system, a hydraulic pump, a Coriolis mass flowmeter, and a high-precision backpressure sensor. The control computer is connected to the intelligent control system and can automatically achieve continuous adjustment of the backpressure with an accuracy of up to 0.172 MPa (25 psi).

[0040] 2. The blowout preventer group of the deepwater drilling platform is installed on the seabed. After gas enters the riser system, the key MPD equipment on the riser can seal the annulus, safely control and circulate the mud, and circulate and discharge the gas in the riser annulus of the well to avoid potential safety hazards.

[0041] 3. For the narrow density window in high-temperature and high-pressure deepwater drilling in the South China Sea, across the low-pressure (500 psi) mud diverter and telescopic riser below the platform rotary table surface, backpressure control is implemented on the annulus fluid from the rotary control sub on the riser to achieve the purpose of balancing the bottom hole pressure and implementing pressure control and safe and efficient drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a schematic structural diagram of the present invention;

[0043] In the figure: 1 - rotary table, 2 - mud diverter, 3 - riser expansion joint, 4 - riser booster pump, 5 - riser tension ring, 6 - metering tank pump, 7 - riser rotary control sub, 8 - MPD hydraulic control sub, 9 - riser annulus seal device, 10 - riser four-way, 11 - drilling riser, 12 - subsea blowout preventer stack, 13 - subsea wellhead;

[0044] 14 - metering tank, 15 - MPD buffer manifold, 16 - MPD filter manifold, 17 - mud shaker, 18 - MPD hydraulic control manifold, 19 - rig choke manifold, 20 - MPD choke manifold, 21 - MPD mud-gas separator, 22 - rig mud-gas separator. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0046] This system is applicable to deepwater (water depth above 300 m) semi-submersible drilling platforms, drill ships, etc. for implementing pressure control drilling and related operations. A pressure control drilling system and drilling method for deepwater drilling in deep sea areas of the present invention, the system includes a riser rotary control sub 7, an MPD hydraulic control sub 8, a riser annulus seal device 9, a riser four-way 10, etc. integrated on an independent riser joint, and its corresponding key surface equipment: an MPD choke manifold 20, an MPD hydraulic control manifold 18, an MPD buffer manifold 15, an MPD filter manifold 16, an MPD mud-gas separator 21, etc. form a system, and are used in combination with equipment such as a riser booster pump 4, a metering tank pump 6, a rotary table 1, a mud diverter 2, a riser expansion joint 3, a riser tension ring 5, a drilling riser 11, a subsea blowout preventer stack 12, a subsea wellhead, etc. of conventional deepwater drilling equipment.

[0047] As Figure 1 shown, a pressure control drilling system for deepwater drilling in deep sea areas of the present invention includes:

[0048] Rotary table 1, mud diverter 2, riser slip joint 3, riser booster pump 4, riser tension ring 5, metering tank pump 6, riser rotation control sub 7, MPD hydraulic control sub 8, riser annulus seal device 9, riser four-way 10, drilling riser 11, subsea blowout preventer stack 12, subsea wellhead 13.

[0049] Below the rotary table 1 is installed the mud diverter 2, and the mud diverter 2 is respectively connected to the metering tank 14, MPD buffer manifold 15, MPD filter manifold 16, and mud shaker 17 through pipeline Ⅰ; the mud diverter 2 is connected to the metering tank pump 6 through pipeline Ⅱ, and the metering tank pump 6 is connected to the metering tank 14.

[0050] At the lower end of the mud diverter 2 is installed the first section of the riser. The riser slip joint 3 is installed at the connection between the first section of the riser and the second section of the riser. The lower end of the riser tension ring 5 is installed on the second section of the riser; the riser rotation control sub 7 is installed at the lower end of the second section of the riser. The riser rotation control sub 7 is connected to the MPD buffer manifold 15 through pipeline Ⅳ. At the lower end of the riser rotation control sub 7 is installed the MPD hydraulic control sub 8. The riser annulus seal device 9 is installed on the lower side of the MPD hydraulic control sub 8. The riser four-way 10 is installed on the lower side of the riser annulus seal device 9. The riser four-way 10 is connected to the MPD buffer manifold 15 through pipeline Ⅵ, and the riser four-way 10 is connected to the MPD buffer manifold 15 through pipeline Ⅶ.

[0051] The riser booster pump 4 is connected to the MPD buffer manifold 15 through pipeline Ⅲ, and the lower end of the riser booster pump 4 is connected to the subsea blowout preventer stack 12 through a booster pipeline.

[0052] The MPD hydraulic control sub 8 is connected to the MPD hydraulic control manifold through a riser accessory pipeline;

[0053] The drilling riser 11 is installed on the lower side of the riser four-way 10. The subsea blowout preventer stack 12 is installed on the lower side of the drilling riser 11. The subsea blowout preventer stack 12 is connected to the rig choke manifold 19 through a choke pipeline, and the subsea blowout preventer stack 12 is connected to the rig choke manifold 19 through a kill pipeline.

[0054] Below the subsea blowout preventer stack 12 is installed the subsea wellhead 13.

[0055] The MPD buffer manifold 15 is connected to the MPD filtration manifold 16 through pipeline VIII. The MPD buffer manifold 15 is respectively connected to the MPD choke manifold 20 and the MPD mud-gas separator 21 through pipeline IX. The MPD buffer manifold 15 is connected to the rig choke manifold 19 through pipeline X. The MPD filtration manifold 16 is connected to the MPD choke manifold 20 through pipeline XI. The shale shaker 17 is respectively connected to the MPD mud-gas separator 21 and the rig mud-gas separator 22 through pipeline XII. Both the MPD mud-gas separator 21 and the rig mud-gas separator 22 have exhaust ports. The rig choke manifold 19 is connected to the rig mud-gas separator 22 through pipeline i. The MPD choke manifold 20 is connected to the MPD mud-gas separator 21.

[0056] Further, the MPD hydraulic control sub-section 8 is an integrated electro-hydraulic control device for the riser rotation control sub-section 7 and the riser annulus seal device 9. The cable of the device communicates with platform equipment and receives control instructions through the riser accessory pipeline channel.

[0057] A drilling method for a managed pressure drilling system in deep water in a deep sea area of the present invention includes three working modes:

[0058] Mode 1. Deep water managed pressure drilling:

[0059] Deep water managed pressure drilling is similar to the purpose of drilling on an offshore shallow water jack-up platform. It is mainly used in formations with a narrow mud density window, or special formations such as high-temperature and high-pressure wells. It can also use MPD managed pressure drilling in the well section above the oil and gas layer. This situation is conducive to detecting gas invasion and overflow in a safe drilling mode, and then discovering the oil and gas layer.

[0060] During the implementation process:

[0061] Step 1. Install the deep water managed pressure drilling integrated device and all related equipment into the equipment process of the semi-submersible drilling rig, and debug to normal.

[0062] Step 2. Start the managed pressure drilling operation procedure. By opening the working valve of the riser rotation control sub-section 7, apply backpressure by circulating mud through the MPD choke manifold 20, transfer the pressure to the bottom of the well through the riser annulus, and keep the hydrostatic pressure greater than the formation pressure with a certain accuracy, and adopt slightly overbalanced drilling.

[0063] Step 2. When encountering formation high pressure, without adjusting the mud density, the throttle pressure can be quickly adjusted to increase the bottom hole pressure to balance the formation high pressure and ensure the safety of the drilling operation.

[0064] Mode 2. Deep water managed pressure mud cap drilling (PMCD):

[0065] When using MPD overbalanced drilling and there is severe formation loss, it can be switched to the pressure-controlled mud cap drilling mode. PMCD drilling needs to avoid pressure fluctuations, accurately determine the formation pressure, maintain the mud column liquid level in the annulus (riser), reduce the mud column pressure to be slightly equal to the formation loss pressure, achieve maintaining a balanced formation, and complete the drilling operation for this well section.

[0066] During MPD operations, prepare and use overbalanced drilling fluid:

[0067] Step 1. Before the start of the drilling operation, fill the deepwater kill line with base oil.

[0068] Step 2. Drill in the MPD mode at an acceptable loss rate.

[0069] Step 3. When a large amount of loss occurs, close the subsea BOP blowout preventer.

[0070] Step 4. Use the kill line to add the mud column pressure below the BOP and the static pressure of the kill line to determine the reservoir pressure or formation fracture pressure.

[0071] Step 5. Gradually lower the riser mud column liquid level until it is just less than the formation fracture pressure of the drilled formation.

[0072] Step 6. Continue to drill in the PMCD mode. Fill the riser with seawater from the upper part of the riser to maintain pressure balance in the well. [[ID=...]]

[0073] Mode 3. Normal drilling mode

[0074] For formations with a wide mud density window and insensitive to the requirement of balancing formation pressure, and with stable formations, normal drilling mode can be used for drilling.

[0075] Step 1. Close all circulation valves and various electrical appliances of the pressure-controlled drilling surface equipment and stop operation.

[0076] Step 2. Remove the rotating seal assembly from the riser rotating control sub 7.

[0077] Step 3. The channel of the riser annulus seal device 9 is in the open state (in a non-sealed state).

[0078] Step 4. The wellbore liquid column pressure is greater than the formation pressure, which belongs to overpressure drilling.

[0079] Example

[0080] Deepwater drilling platforms in the South China Sea, such as the Offshore Oil 981 and Offshore Oil 982 platforms, usually have a rotary table diameter of 153.67 cm (60.5 in). Structurally, the disadvantages of conventional rotary control heads and annular seal devices that cannot pass through the rotary table are improved. The outer diameter of the equipment is reduced, and the total height is increased. The top drive device is used to lower it under the platform wellhead through the rotary table 1 and connect it to the drilling riser 11.

[0081] Components such as the riser rotation control sub 7, MPD hydraulic control sub 8, riser annulus seal device 9, and riser four-way 10 have the largest external dimensions as compact as possible and smaller than the diameter of the deepwater platform rotary table 1. The total system design length can be controlled within 18 m or the length of a single section of the drilling riser (22.86 m). The lengths of each part within the system are designed and optimized to facilitate hoisting, wellhead connection, testing, etc. on the platform.

[0082] Drill pipes with a diameter of 139.7 mm - 168.275 mm (5.5 - 6.875 in) are used, and the maximum drill string outer diameter sealed by the seal assembly is 475.488 mm (18.75 in). The maximum working pressure of the system is 13.79 MPa (2000 psi). The rated dynamic pressure of the riser rotation control sub 7 is: the dynamic rated seal pressure at a drill pipe rotation speed of 160 r / s is 10.34 MPa (1500 psi); the rated seal pressure during tripping is 6.895 MPa (1000 psi).

[0083] The riser rotation control sub 7 and the riser annulus seal device 9 are installed below the riser expansion joint 3, involving more stringent sealing and anti-corrosion requirements than the equipment on the platform.

[0084] The single section of the deepwater drilling riser managed pressure drilling integrated device is 15.24 m - 19.05 m (50 - 75 ft), and the weight reaches 20 t - 30 t, matching the weight of a single column of the drilling riser. The structures and weights of the riser rotation control sub 7 and the riser annulus seal device 9 are optimized to facilitate connection installation and lowering at the wellhead.

[0085] The deepwater riser managed pressure drilling integrated device is installed above the riser system and must meet deepwater drilling and engineering specifications such as API 16Q, withstand the huge tension of thousands of tons of the drilling riser system, and provide good material mechanical properties of the equipment to ensure the safety of deepwater drilling operations.

[0086] The MPD buffer manifold 15 is simultaneously equipped with a riser pressure relief valve of 5.171 MPa (750 psi), a riser rupture disc of 5.516 MPa (800 psi), and a riser boost line pressure relief valve of 34.475 MPa (5000 psi) to protect the riser and its attached pipelines. The MPD filter manifold 16 is used to filter out larger mud cuttings to prevent clogging of the MPD choke manifold 20.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements 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 pressure control drilling system for deep - water drilling in deep - sea areas, characterized in that: It includes a rotary table, a mud diverter, a riser slip joint, a riser booster pump, a riser tension ring, a metering tank pump, a riser rotary control sub, an MPD hydraulic control sub, a riser annulus seal assembly, a riser four-way, a drilling riser, a subsea blowout preventer (BOP) stack, and a subsea wellhead; The mud diverter is installed on the lower side of the rotary table. The mud diverter is connected to the metering tank, the MPD buffer manifold, the MPD filtration manifold, and the shale shaker respectively through Pipeline Ⅰ; the mud diverter is connected to the metering tank pump through Pipeline Ⅱ, and the metering tank pump is connected to the metering tank; The first section of the riser is installed at the lower end of the mud diverter; the riser slip joint is installed at the connection between the first section of the riser and the second section of the riser, and the lower end of the riser tension ring is installed on the second section of the riser; the riser rotary control sub is installed at the lower end of the second section of the riser. The riser rotary control sub is connected to the MPD buffer manifold through Pipeline Ⅳ. The MPD hydraulic control sub is installed at the lower end of the riser rotary control sub. The riser annulus seal assembly is installed on the lower side of the MPD hydraulic control sub. The riser four-way is installed on the lower side of the riser annulus seal assembly. The riser four-way is connected to the MPD buffer manifold through Pipeline Ⅵ, and the riser four-way is connected to the MPD buffer manifold through Pipeline Ⅶ; The riser booster pump is connected to the MPD buffer manifold through Pipeline Ⅲ. The lower end of the riser booster pump is connected to the subsea BOP stack through a booster pipeline. The MPD hydraulic control sub is connected to the MPD hydraulic control manifold through a riser accessory pipeline; the drilling riser is installed on the lower side of the riser four-way, and the subsea BOP stack is installed on the lower side of the drilling riser. The subsea BOP stack is connected to the rig choke manifold through a choke pipeline and is connected to the rig choke manifold through a kill pipeline; The subsea wellhead is installed on the lower side of the subsea BOP stack. The MPD buffer manifold is connected to the MPD filtration manifold through Pipeline Ⅷ, and the MPD buffer manifold is connected to the MPD choke manifold and the MPD mud-gas separator respectively through Pipeline Ⅸ; the MPD buffer manifold is connected to the rig choke manifold through Pipeline Ⅹ; the MPD filtration manifold is connected to the MPD choke manifold through Pipeline Ⅺ. The shale shaker is connected to the MPD mud-gas separator and the rig mud-gas separator respectively through Pipeline Ⅻ. Both the MPD mud-gas separator and the rig mud-gas separator have exhaust ports. The rig choke manifold is connected to the rig mud-gas separator through Pipeline ⅰ; the MPD choke manifold is connected to the MPD mud-gas separator.

2. The pressure control drilling system for deep - water drilling in deep - sea areas according to claim 1, wherein, The MPD buffer manifold is equipped with a 5.171 MPa riser pressure relief valve, a 5.516 MPa riser rupture disk, and a 34.475 MPa riser booster pipeline pressure relief valve to protect the drilling riser and its accessory pipelines.

3. The pressure control drilling system for deepwater drilling in deep sea areas according to claim 1, wherein The MPD filtration manifold is used to filter out larger mud cuttings to prevent clogging of the MPD choke manifold.

4. A method for drilling a well using a pressure control drilling system for deepwater drilling in deep sea areas as described in any one of claims 1 to 3, characterized in that, It includes: Deepwater managed pressure drilling: Step 1. Install the deepwater managed pressure drilling integrated device and all related equipment into the equipment process of the semi-submersible drilling rig and debug it to normal; Step 2. Start the managed pressure drilling operation procedure, open the working valve of the riser rotary control sub, apply backpressure by circulating mud through the MPD choke manifold, transfer the pressure to the bottom hole through the riser annulus, keep the hydrostatic pressure greater than the formation pressure with a certain accuracy, and adopt slightly overbalanced drilling. Step 3. When encountering high formation pressure, quickly adjust the choke pressure without adjusting the mud density to ensure the safety of the drilling operation.

5. The drilling method of the pressure control drilling system for deepwater drilling in deep sea areas according to claim 4, characterized in that: It also includes deepwater managed pressure mud cap drilling: Step 1. Before the drilling operation starts, fill the deepwater kill line with base oil. Step 2. Drill with the MPD mode under the accepted lost circulation volume condition. Step 3. When a large amount of lost circulation occurs, close the subsea BOP blowout preventer. Step 4. Use the kill line, add the hydrostatic pressure of the mud column below the BOP and the static pressure of the kill line to determine the reservoir pressure or formation fracture pressure. Step 5. Gradually lower the mud column level in the riser until it is just less than the formation fracture pressure of the formation being drilled. Step 6. Continue to drill with the PMCD mode, fill the riser with seawater from the upper part of the riser to maintain the well pressure balance.

6. The drilling method of the pressure control drilling system for deep - water drilling in deep - sea areas according to claim 4, characterized in that: It also includes the normal drilling mode: Step 1. Close all circulation valves and various electrical appliances of the managed pressure drilling surface equipment and stop running. Step 2. Remove the rotating seal assembly from the riser rotary control sub. Step 3. The riser annulus seal device channel is in the open state. Step 4. The hydrostatic pressure in the well is greater than the formation pressure, which belongs to overbalanced drilling.

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