Deepwater drilling platform tensioning ring lower pressure control drilling device and method

Abstract

The invention provides a deepwater drilling platform tensioning ring lower pressure control drilling device and method.The device comprises an upper conversion connector, and the lower end of the upper conversion connector is sequentially connected with a rotation control device, an annulus packing device, a marine riser four-way joint and a lower conversion connector; and the device is matched with equipment such as a shunting manifold, a throttle manifold, a grouting pump, a back-pressure pump, a liquid-gas separator, a slurry elevated tank, a hydraulic control pry, a pressure control explosion-proof room and a logging room for use. The gathered gas between the marine riser four-way joint and the rotation control device is taken away from the annulus through the line pipe, the ball valve, the throttling manifold and the flow dividing manifold, gas exhaust is achieved, and major potential safety hazards in the operation of replacing a rotation assembly sealing system are eliminated. And the upper pressure and the lower pressure are balanced through the annular packer device, the line pipe and the ball valve, the abrasion rate of a rubber core of the annular packer is reduced, the service life of the rubber core is prolonged, the deepwater pressure control drilling non-generation time is shortened, and the drilling efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of deepwater petroleum and natural gas exploration and development, and in particular relates to a pressure-controlled drilling device and method under a tension ring of a deepwater drilling platform. Background Art

[0002] Deepwater drilling is different from conventional shallow-water drilling and land drilling. The mud diverter and telescopic riser near the wellhead of the drilling platform have low pressure-bearing capacity and cannot meet the needs of pressure-controlled drilling. The deepwater well control blowout preventer (BOP) is placed in the deepwater environment of the seabed (low temperature, high pressure, and the presence of hydrates), making deepwater well control more complicated and drilling risks increase dramatically.

[0003] At present, there are generally two types of offshore drilling platform controlled pressure drilling modes, ATR (Above Tensioner Ring) and BTR (Below Tensioner Ring). Among them, ATR mode controlled pressure drilling is a controlled pressure drilling method established by installing the rotary control device of the closed wellhead annulus on the tension ring of the drilling riser system, but this mode is only applicable to shallow water areas (within 300m of water depth) and cannot be applied to deep-water offshore drilling. BTR mode controlled pressure drilling is to install the rotary control device of the closed wellhead annulus under the tension ring of the drilling riser system, and install an annular sealing assembly under the rotary control device. This mode can better meet the needs of deep-water offshore controlled pressure drilling processes and technologies.

[0004] Patent CN116065961A discloses a pressure-controlled drilling system and drilling method for deep-water drilling in deep sea areas. The method in this patent belongs to the BTR mode pressure-controlled drilling technology, and its system includes a rotary table, a mud diverter, a riser expansion joint, a riser booster pump, a riser tension ring, a metering tank pump, a riser rotation control nipple, an MPD hydraulic control nipple, a riser annulus sealing device, a riser spool, a drilling riser, an underwater blowout preventer group, a seabed underwater wellhead and other equipment, which can be used together with deepwater (water depth of more than 300m) semi-submersible drilling platform and related drilling operations.

[0005] Patent CN117759195A discloses a BTR pressure-controlled drilling assembly structure under the tension ring of a semi-submersible drilling platform. It mainly includes two parts: a rotation control device and an annulus isolation device. The BTR pressure-controlled drilling system assembly structure is installed under the tension ring of the drilling riser system of an offshore semi-submersible drilling platform. It is connected to the bottom end of the outer tube at the lower end of the riser expansion joint, and the lower part is connected to the drilling riser system. In the overall redesigned system structure, a controllable annulus isolation device that meets the requirements for underwater use.

[0006] However, the problems existing in the prior art are:

[0007] 1. Gas aggregates in the BTR short joint lead to operational accidents. The integrated pressure-controlled short joint under the tensioning ring (BTR pressure-controlled drilling short joint) is mainly composed of three parts from top to bottom: a rotary control device, an annulus isolation device, and a watertight pipe four-way. During the pressure-controlled drilling process, the rotary control device seals the annulus, and the drilling fluid returns to the ground throttling system from the side outlet of the drilling four-way. Due to the incompressibility of the liquid, when the annulus isolation device closes the annulus, the pressure in the lower part of the annulus cannot be transmitted to the rotary control device. At this time, the rotary assembly sealing system can be replaced normally. When gas invasion occurs, the gas invading the annulus gathers in the annulus section from the four-way to the rotary assembly. When the annulus isolation device closes the annulus, the gas isolated between the annulus isolation device and the rotary control assembly still maintains a relatively high pressure. At this time, replacing the rotary assembly sealing system is very likely to cause a production safety accident, causing damage to equipment and personnel.

[0008] 2. After the annulus packer seals the annulus, the imbalance of upper and lower pressures damages the sealant core, increasing non-productive time. During normal operation, when the annulus packer is used to seal the annulus under pressure, a pressure difference is formed between the upper and lower parts of the sealant core. At this time, the operation of moving the drill string or opening the core again will cause great damage to the sealant core. When the sealant core of the annular packer is damaged and replaced, it is necessary to adjust the mud density to balance the bottom hole pressure, remove all drilling tools, lift the riser system, and remove the entire BTR pressure control short joint. The operation is cumbersome and takes several hours or even days to replace, which greatly increases the non-productive time of the platform. In the case of deepwater drilling platforms with daily fees of tens of thousands or even hundreds of thousands of dollars, it will greatly increase the drilling cost and affect the drilling efficiency. Summary of the invention

[0009] The purpose of the present invention is to provide a deepwater controlled pressure drilling device and method for processing accumulated gas and balancing the upper and lower pressures of the ring seal in order to solve the above problems existing in the existing deepwater controlled pressure drilling equipment and methods.

[0010] The present invention provides a tension ring-down controlled pressure drilling device for a deepwater drilling platform, comprising an upper conversion joint, wherein a rotation control device, an annulus isolation device, a watertight pipe spool, and a lower conversion joint are sequentially connected downward from the top of the upper conversion joint;

[0011] The rotating device is connected to the grouting pump through the line pipe I, ball valve II, line pipe II, shunt manifold, and line pipe III; the rotating control device is connected to the throttling manifold through the line pipe I, ball valve II, line pipe II, shunt manifold, and pipeline V; the rotating control device is connected to the back pressure pump through pipeline I, ball valve II, pipeline II, shunt manifold, and pipeline VI;

[0012] The riser spool is connected to the rotary control device through ball valve I1 and pipeline I; the riser spool is connected to the throttling manifold through ball valve III, pipeline IV, shunt manifold and pipeline V; the shunt manifold is connected to the back pressure pump through pipeline VI;

[0013] The throttling manifold is connected to the liquid-gas separator through the outlet pipeline I and is connected to the mud elevated tank of the drilling platform through the outlet pipeline II;

[0014] The hydraulic control skid is connected to the integrated pressure control nipple through a hydraulic control pipeline;

[0015] The pressure control and explosion-proof room is connected to the throttling manifold through cable line I; the pressure control and explosion-proof room is connected to the logging room through cable line II.

[0016] Furthermore, the diversion manifold includes a tee I, a tee II, a tee III, a flat valve I, a flat valve II, a flat valve III, a flat valve IV, a flat valve V, a flat valve VI, and a flat valve VII.

[0017] Furthermore, the integrated pressure-controlling short joint includes an upper conversion joint, a rotation control device, an annulus isolation device, a watertight pipe four-way, a lower conversion joint, a ball valve I, a ball valve II, a ball valve III, and a line pipe I.

[0018] A controlled pressure drilling method under a tension ring of a deepwater drilling platform, comprising conventional deepwater drilling:

[0019] Step 1: Install the deepwater pressure-controlled drilling device and all related equipment into the deepwater drilling platform and debug them to normal;

[0020] Step 2: Adjust the valves of the diversion manifold, close the flat valves I, III, and VI, and open the flat valves II, IV, V, and VII; operate the hydraulic control skid, adjust the integrated pressure control nipple valve, close the ball valves I and II, and open the ball valve III; connect the riser spool, diversion manifold, throttling manifold, and back pressure pump through pipelines IV, V, and VI; start the pressure control drilling operation procedure;

[0021] Step 3, during normal drilling, the rotary control device seals the annulus, the riser spool guides the returned mud into the diversion manifold, and then flows into the throttling manifold. After throttling, the mud flows into the liquid-gas separator through the outlet pipeline I or the outlet pipeline II into the platform mud elevated tank; the pressure control and explosion-proof room controls the throttling manifold to adjust the back pressure according to the return mud flow monitored by the throttling manifold or the formation pressure provided by the logging room. The back pressure applied by the throttling manifold is transmitted to the riser annulus through pipeline V, pipeline IV, and the riser spool in turn, and then the pressure is transmitted to the bottom of the well through the riser annulus to keep the accuracy of the annulus liquid column pressure within the designed pressure range;

[0022] Step 4: When a single drill string is connected, the mud circulation in the well stops, and the back pressure pump is started. The back pressure pump provides mud circulation power. The pressure control and explosion-proof room controls the throttling manifold to adjust the back pressure according to the formation pressure provided by the logging room. After throttling, the mud flows into the liquid-gas separator through the outlet pipeline I or the outlet pipeline II into the platform mud elevated tank; the back pressure of the throttling manifold is transmitted to the riser annulus through pipeline V, pipeline IV, and riser four-way in turn, and then the pressure is transmitted to the bottom of the well through the riser annulus, so as to keep the accuracy of the annulus liquid column pressure within the designed pressure range;

[0023] Step 5: When the formation pressure changes, without adjusting the mud density, the pressure control and explosion-proof room adjusts the throttle manifold to adjust the back pressure according to the return mud flow monitored by the throttle manifold or the formation pressure provided by the logging room to ensure the bottom hole pressure balance.

[0024] A controlled pressure drilling method under a tension ring of a deepwater drilling platform, and also includes a method for circulating and exhausting concentrated gas in deepwater controlled pressure drilling:

[0025] Step 1, operate the hydraulic control skid, adjust the integrated pressure control nipple valve, close ball valve I and ball valve III, and open ball valve II; adjust the valve of the shunt manifold, close flat valve II and flat valve III, and open flat valve I, flat valve IV, flat valve V, flat valve VI, and flat valve VII; the rotation control device is connected to the shunt manifold through pipeline I, ball valve II, and pipeline II, connected to the throttling manifold through pipeline V, and connected to the back pressure pump through pipeline VI;

[0026] Step 2: Perform normal pressure-controlled drilling mud circulation. The annular mud reaches the liquid-gas separator through the rotary control device, the diversion manifold, the throttling manifold, and the outlet pipeline I. During the mud circulation process, the accumulated gas between the water-receiving pipe spool and the rotary control device is taken away from the annular space and enters the liquid-gas separator for separation and treatment;

[0027] Step 3. After the accumulated gas treatment is completed, operate the hydraulic control skid, adjust the integrated pressure control short joint valve, close the ball valve II, and open the ball valve III; adjust the diversion manifold valve again to be consistent with the valve state of the diversion manifold in the conventional deepwater pressure control drilling method, connect the watertight pipe four-way with the pipeline V and the throttling manifold, and carry out the normal pressure control drilling cycle.

[0028] A controlled pressure drilling method under a tension ring of a deepwater drilling platform, and also includes a method for replacing a sealing assembly of a rotary control device in deepwater controlled pressure drilling:

[0029] Step 1: Based on the normal controlled pressure drilling method, adjust the valve of the diversion manifold, close the flat valve I, open the flat valve II, flat valve III, flat valve IV, flat valve V, flat valve VI, flat valve VII, connect the riser spool with the grouting pump, back pressure pump, and throttling manifold through pipelines III, IV, V, and VI, and open the back pressure pump to provide ground mud circulation power;

[0030] Step 2: Operate the hydraulic control pry to control the annular space isolation device to close the sealing rubber core and seal the annular space; operate the hydraulic control pry again to unlock the sealing assembly of the rotary control device, lift the drill string to take out the sealing assembly of the rotary control device, replace the sealing original of the sealing assembly, lower the drill string to lower the sealing assembly of the rotary control device to the set position of the rotary control device, and operate the hydraulic control pry to lock it;

[0031] Step 3, operate the hydraulic control pry to open the ball valve I, so that the upper and lower annuli of the sealing rubber core of the annulus isolation device are connected through the ball valve I, pipeline I, and the rotary control device to achieve pressure balance;

[0032] Step 4: Operate the hydraulic control pry to open the sealing rubber core of the annulus isolation device, close the ball valve I, adjust the valve of the diversion manifold to make it consistent with the valve state of the diversion manifold in the conventional deepwater controlled pressure drilling method, and continue the conventional deepwater controlled pressure drilling work.

[0033] Beneficial effects:

[0034] 1. The present application changes the traditional BTR short-joint gas-gathering state in which the gas is in a high-pressure state. The gathered gas between the watertight pipe spool and the rotating control device is brought away from the annulus through the wire pipe, ball valve, throttling manifold and diversion manifold to discharge the gas, thereby solving the problem of BTR short-joint gas-gathering operation accidents and eliminating major safety hazards in the operation of replacing the rotating assembly sealing system.

[0035] 2. A device and method for balancing the upper and lower pressures of an annular packer are provided, which reduces the wear rate of the rubber core of the annular packer, increases the service life of the rubber core, reduces the non-productive time of deepwater controlled pressure drilling, and improves drilling efficiency.

[0036] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic structural diagram of a tension ring-under-pressure drilling device for a deepwater drilling platform provided by the present invention;

[0038] Figure 2 It is a structural schematic diagram of the diversion manifold provided by the present invention.

[0039] Figure numerals: 1-upper conversion joint, 2-rotation control device, 3-annulus isolation device, 4-waterproof pipe spool, 5-lower conversion joint, 6-diversion manifold, 7-throttling manifold, 8-hydraulic control skid, 9-pressure control explosion-proof room, 10-grouting pump, 11-back pressure pump, 12-liquid-gas separator, 13-elevated tank, 14-logging room, 15-integrated pressure control short joint, 16-ball valve I, 17-ball valve II, 18-ball valve III, 19-pipeline I, 20-pipeline II, 21-pipeline III, 22-pipeline IV, 23-pipeline V , 24- pipeline VI, 25- export pipeline I, 26- export pipeline II, 27- hydraulic control pipeline, 28- cable line, 29- outer tube of expansion joint of watertight pipe, 30- tensioning ring, 31- hydraulic control pipeline, 32- cable line I, 33- cable line II, 601- tee I, 602- tee II, 603- tee III, 604- flat valve I, 605- flat valve II, 606- flat valve III, 607- flat valve IV, 608- flat valve V, 609- flat valve VI, 610- flat valve VII. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] The application principle of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0042] Embodiment 1:

[0043] like Figure 1 and Figure 2 As shown, a tension ring-down controlled pressure drilling device for a deepwater drilling platform provided by the present invention comprises an upper conversion joint 1, a riser expansion joint outer cylinder 29 is connected to the top of the upper conversion joint 1, a tension ring 30 is connected to the top of the riser expansion joint outer cylinder 29, and a rotation control device 2, an annulus isolation device 3, a riser spool 4, and a lower conversion joint 5 are sequentially connected from the top of the upper conversion joint 1 downward. The lower part of the lower conversion joint 5 is connected to the riser of the drilling platform.

[0044] The rotation control device 2 is connected to the grouting pump 10 through the pipeline I19, the ball valve II17, the pipeline II20, the diversion manifold 6, and the pipeline III21. The rotation control device 2 is connected to the throttling manifold 7 through the pipeline I19, the ball valve II17, the pipeline II20, the diversion manifold 6, and the pipeline V23. The rotation control device 2 is connected to the back pressure pump 11 through the pipeline I19, the ball valve II17, the pipeline II20, the diversion manifold 6, and the pipeline VI24.

[0045] The riser spool 4 is connected to the rotation control device 2 through the ball valve I16 and the pipeline I19. The riser spool 4 is connected to the throttling manifold 7 through the ball valve III18, the pipeline IV22, the diverter manifold 6, and the pipeline V23. The diverter manifold 6 is connected to the back pressure pump 11 through the pipeline VI24.

[0046] The diversion manifold 6 is composed of a tee I601, a tee II602, a tee III603, a flat valve I604, a flat valve II605, a flat valve III606, a flat valve IV607, a flat valve V608, a flat valve VI609, and a flat valve VI607.

[0047] The throttling manifold 7 is connected to the liquid-gas separator 12 through the outlet pipeline I25 and is connected to the drilling platform mud elevated tank 13 through the outlet pipeline II26.

[0048] The hydraulic control skid 8 is connected to the integrated pressure control nipple 15 via a hydraulic control pipeline 31 .

[0049] The upper conversion joint 1, the rotation control device 2, the annulus isolation device 3, the watertight pipe spool 4, the lower conversion joint 5, the ball valve I16, the ball valve II17, the ball valve III18, and the pipeline I19 together constitute an integrated pressure control short joint 15.

[0050] The pressure control explosion-proof room 9 is connected to the throttle manifold 7 via cable I32. The pressure control explosion-proof room 9 is connected to the logging room 14 via cable II33.

[0051] The present invention provides a controlled pressure drilling method under a tension ring of a deepwater drilling platform, wherein the conventional deepwater controlled pressure drilling method is:

[0052] Step 1: Install the deepwater pressure-controlled drilling device and all related equipment into the deepwater drilling platform and debug them to normal;

[0053] Step 2, adjust the valves of the diversion manifold 6, close the flat valve I604, flat valve III606, and flat valve VI609, and open the flat valve II605, flat valve IV607, flat valve V608, and flat valve VII610; operate the hydraulic control skid 8, remotely adjust the valve of the integrated pressure control short joint 15, close the ball valve I16 and ball valve II17, and open the ball valve III18; connect the watertight pipe four-way 4, the diversion manifold 6, the throttling manifold 7, and the back pressure pump 11 through pipelines IV22, V23, and VI24; start the pressure control drilling operation procedure.

[0054] Step 3, during normal drilling, the rotary control device 2 seals the annulus, the riser spool 4 guides the returned mud into the shunt manifold 6, and then flows into the throttle manifold 7 through the shunt manifold 6. The pressure control explosion-proof room 9 controls the throttle manifold 7 to adjust the back pressure according to the return mud flow monitored by the throttle manifold 7 or the formation pressure provided by the logging room 14. After throttling, the mud flows into the liquid-gas separator 12 or the platform mud elevated tank 13 through the outlet pipeline I25 or the outlet pipeline II26. The back pressure applied by the throttle manifold 7 is transmitted to the riser annulus through the pipeline V23, the pipeline IV22, and the riser spool 4 in turn, and then the pressure is transmitted to the bottom of the well through the riser annulus to keep the accuracy of the annular liquid column pressure within the designed pressure range.

[0055] Step 4, when a single drill string is connected, the mud circulation in the well stops, and the back pressure pump 11 is started at this time. The back pressure pump 11 provides mud circulation power, and the pressure control explosion-proof room 9 controls the throttling manifold 7 to adjust the back pressure according to the formation pressure provided by the logging room 14. After throttling, the mud flows into the liquid-gas separator 12 through the outlet pipeline I25 or flows into the platform mud elevated tank 13 through the outlet pipeline II26. The back pressure of the throttling manifold 7 is transmitted to the riser annulus through the pipeline V23, the pipeline IV22, and the riser spool 4 in turn, and then the pressure is transmitted to the bottom of the well through the riser annulus, so as to keep the annulus liquid column pressure within the design pressure range with a certain accuracy.

[0056] Step 5. When encountering formation pressure changes, without adjusting the mud density, the pressure control and explosion-proof room 9 can quickly adjust the throttle manifold 7 to adjust the back pressure according to the return mud flow monitored by the throttle manifold 7 or the formation pressure provided by the logging room 14 to ensure the bottom hole pressure balance and ensure the safety of the drilling operation.

[0057] A controlled pressure drilling method under a tension ring of a deepwater drilling platform, wherein the concentrated gas circulation exhaust method of the deepwater controlled pressure drilling is:

[0058] After a period of normal controlled pressure drilling, due to the invasion of formation gas, accumulated gas is formed in the annulus section between the riser spool 4 and the rotary control device 2. At this time, based on the normal controlled pressure drilling mode, the accumulated gas circulation exhaust operation is performed.

[0059] Step 1, operate the hydraulic control skid 8, remotely adjust the integrated pressure control nipple 15 valve, close the ball valve I16, ball valve III18, and open the ball valve II17. Adjust the valves of the diversion manifold 6, close the flat valve II605, flat valve III606, and open the flat valve I604, flat valve IV607, flat valve V608, flat valve VI609, and flat valve VII610. After adjusting the valves, the passage between the riser 4 and the diversion manifold 6 is disconnected, and the rotation control device 2 is connected to the diversion manifold 6 through the pipeline I19, ball valve II17, and pipeline II20, connected to the throttling manifold 7 through the pipeline V23, and connected to the back pressure pump 11 through the pipeline VI24.

[0060] Step 2, perform normal pressure-controlled drilling mud circulation. The annulus mud reaches the liquid-gas separator 12 through the rotary control device 2, the diversion manifold 6, the throttling manifold 7, and the outlet pipeline I25. During the mud circulation process, the accumulated gas between the watertight pipe 4 and the rotary control device 2 is taken away from the annulus and enters the liquid-gas separator 12 for separation and treatment.

[0061] Step 3: After the treatment of the accumulated gas is completed, the hydraulic control skid 8 is operated to remotely adjust the valve of the integrated pressure control nipple 15 to close the ball valve II17 and open the ball valve III18. The valve of the diversion manifold 6 is adjusted to be consistent with the valve state of the diversion manifold 6 in the conventional deepwater pressure control drilling method, so that the watertight pipe spool 4 is connected to the pipeline V23 and the throttle manifold 7, and the normal pressure control drilling cycle is carried out.

[0062] A controlled pressure drilling method under a tension ring of a deepwater drilling platform, wherein a method for replacing a seal assembly of a rotary control device in deepwater controlled pressure drilling is as follows:

[0063] During the controlled pressure drilling process, the sealing assembly of the rotary control device 2 is in a state of continuous wear. After working for a certain period of time, the wear reaches the limit and the sealing assembly needs to be replaced. At this time, the annulus isolation device 3 needs to be used to replace the rotary control device 2 to seal the annulus to isolate the annulus pressure. The key advantage of this mode is that the annulus isolation device 3 is opened, and the upper and lower annuli of the sealing rubber core of the annulus isolation device 3 are connected through the pipeline I19 and the ball valve I16 to balance the upper and lower pressures and reduce the damage to the sealing rubber core.

[0064] Step 1: Based on the conventional deepwater pressure-controlled drilling method, adjust the valves of the diversion manifold 6, close the flat valve I604, open the flat valve II605, flat valve III606, flat valve IV607, flat valve V608, flat valve VI609, flat valve VII610, and connect the riser spool 4 with the grouting pump 10, the back pressure pump 11, and the throttle manifold 7 through pipelines III21, IV22, V23, and VI24. Open the back pressure pump 11 to provide ground mud circulation power.

[0065] Step 2: Operate the hydraulic control pry 8 to control the annulus isolation device 3 to close the sealing rubber core and seal the annulus. Operate the hydraulic control pry 8 again to unlock the sealing assembly of the rotation control device 2, lift the drill string to take out the sealing assembly of the rotation control device 2, replace the sealing original of the sealing assembly, lower the drill string to lower the sealing assembly of the rotation control device 2 to the set position of the rotation control device 2, and operate the hydraulic control pry 8 to lock it.

[0066] Step 3, operate the hydraulic control skid 8 to open the ball valve I16, so that the upper and lower annuli of the sealing rubber core of the annulus isolation device 3 are connected through the ball valve I16 and the pipeline I19, and the rotating control device 2 to achieve pressure balance.

[0067] Step 4: operate the hydraulic control skid 8 to open the sealing rubber core of the annulus isolation device 3, close the ball valve I16, adjust the valve of the diversion manifold 6 to make it consistent with the valve state of the diversion manifold 6 in the conventional deepwater controlled pressure drilling method, and continue the conventional deepwater controlled pressure drilling work.

[0068] 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 and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pressure-controlled drilling device under a tension ring of a deepwater drilling platform, characterized in that: It includes an upper conversion joint, the top of which is sequentially connected with a rotation control device, an annulus isolation device, a riser spool, and a lower conversion joint; The rotating device is connected to the grouting pump through the line pipe I, ball valve II, line pipe II, shunt manifold, and line pipe III; the rotating control device is connected to the throttling manifold through the line pipe I, ball valve II, line pipe II, shunt manifold, and pipeline V; the rotating control device is connected to the back pressure pump through pipeline I, ball valve II, pipeline II, shunt manifold, and pipeline VI; The riser spool is connected to the rotary control device through ball valve I1 and pipeline I; the riser spool is connected to the throttling manifold through ball valve III, pipeline IV, shunt manifold and pipeline V; the shunt manifold is connected to the back pressure pump through pipeline VI; The throttling manifold is connected to the liquid-gas separator through the outlet pipeline I and is connected to the mud elevated tank of the drilling platform through the outlet pipeline II; The hydraulic control skid is connected to the integrated pressure control nipple through a hydraulic control pipeline; The pressure control and explosion-proof room is connected to the throttling manifold through cable line I; the pressure control and explosion-proof room is connected to the logging room through cable line II.

2. The controlled pressure drilling device under the tension ring of a deepwater drilling platform according to claim 1, characterized in that: The shunt manifold includes tee I, tee II, tee III, flat valve I, flat valve II, flat valve III, flat valve IV, flat valve V, flat valve VI and flat valve VII.

3. The controlled pressure drilling device under the tension ring of a deepwater drilling platform according to claim 1, characterized in that: The integrated pressure control nipple includes an upper conversion joint, a rotation control device, an annulus isolation device, a watertight pipe spool, a lower conversion joint, a ball valve I, a ball valve II, a ball valve III, and a line pipe I.

4. A controlled pressure drilling method under a tension ring of a deepwater drilling platform, characterized in that: Including conventional deepwater drilling: Step 1: Install the deepwater pressure-controlled drilling device and all related equipment on the deepwater drilling platform and debug them to normal; Step 2: Adjust the valves of the diversion manifold, close the flat valves I, III, and VI, and open the flat valves II, IV, V, and VII; operate the hydraulic control skid, adjust the integrated pressure control nipple valve, close the ball valves I and II, and open the ball valve III; connect the riser spool, diversion manifold, throttling manifold, and back pressure pump through pipelines IV, V, and VI; start the pressure control drilling operation procedure; Step 3, during normal drilling, the rotary control device seals the annulus, the riser spool guides the returned mud into the diversion manifold, and then flows into the throttling manifold. After throttling, the mud flows into the liquid-gas separator through the outlet pipeline I or the outlet pipeline II into the platform mud elevated tank; the pressure control and explosion-proof room controls the throttling manifold to adjust the back pressure according to the return mud flow monitored by the throttling manifold or the formation pressure provided by the logging room. The back pressure applied by the throttling manifold is transmitted to the riser annulus through pipeline V, pipeline IV, and the riser spool in turn, and then the pressure is transmitted to the bottom of the well through the riser annulus to keep the accuracy of the annulus liquid column pressure within the designed pressure range; Step 4: When a single drill string is connected, the mud circulation in the well stops, and the back pressure pump is started. The back pressure pump provides mud circulation power. The pressure control and explosion-proof room controls the throttling manifold to adjust the back pressure according to the formation pressure provided by the logging room. After throttling, the mud flows into the liquid-gas separator through the outlet pipeline I or the outlet pipeline II into the platform mud elevated tank; the back pressure of the throttling manifold is transmitted to the riser annulus through pipeline V, pipeline IV, and riser four-way in turn, and then the pressure is transmitted to the bottom of the well through the riser annulus, so as to keep the accuracy of the annulus liquid column pressure within the designed pressure range; Step 5: When the formation pressure changes, without adjusting the mud density, the pressure control and explosion-proof room adjusts the throttle manifold to adjust the back pressure according to the return mud flow monitored by the throttle manifold or the formation pressure provided by the logging room to ensure the bottom hole pressure balance.

5. The controlled pressure drilling method under tension ring of deepwater drilling platform according to claim 4, characterized in that: It also includes deepwater managed pressure drilling gas circulation exhaust: Step 1, operate the hydraulic control skid, adjust the integrated pressure control nipple valve, close ball valve I and ball valve III, and open ball valve II; adjust the valve of the shunt manifold, close flat valve II and flat valve III, and open flat valve I, flat valve IV, flat valve V, flat valve VI, and flat valve VII; the rotation control device is connected to the shunt manifold through pipeline I, ball valve II, and pipeline II, connected to the throttling manifold through pipeline V, and connected to the back pressure pump through pipeline VI; Step 2: Perform normal pressure-controlled drilling mud circulation. The annular mud reaches the liquid-gas separator through the rotary control device, the diversion manifold, the throttling manifold, and the outlet pipeline I. During the mud circulation process, the accumulated gas between the water-receiving pipe spool and the rotary control device is taken away from the annular space and enters the liquid-gas separator for separation and treatment; Step 3. After the accumulated gas treatment is completed, operate the hydraulic control skid, adjust the integrated pressure control short joint valve, close the ball valve II, and open the ball valve III; adjust the diversion manifold valve again to be consistent with the valve state of the diversion manifold in the conventional deepwater pressure control drilling method, connect the watertight pipe four-way with the pipeline V and the throttling manifold, and carry out the normal pressure control drilling cycle.

6. The controlled pressure drilling method under a tension ring of a deepwater drilling platform according to claim 4, characterized in that: Also included is the replacement of the rotary control seal assembly for deepwater managed pressure drilling: Step 1: Based on the normal controlled pressure drilling method, adjust the valve of the diversion manifold, close the flat valve I, open the flat valve II, flat valve III, flat valve IV, flat valve V, flat valve VI, flat valve VII, connect the riser spool with the grouting pump, back pressure pump, and throttling manifold through pipelines III, IV, V, and VI, and open the back pressure pump to provide ground mud circulation power; Step 2: Operate the hydraulic control pry to control the annular space isolation device to close the sealing rubber core and seal the annular space; operate the hydraulic control pry again to unlock the sealing assembly of the rotary control device, lift the drill string to take out the sealing assembly of the rotary control device, replace the sealing original of the sealing assembly, lower the drill string to lower the sealing assembly of the rotary control device to the set position of the rotary control device, and operate the hydraulic control pry to lock it; Step 3, operate the hydraulic control pry to open the ball valve I, so that the upper and lower annuli of the sealing rubber core of the annulus isolation device are connected through the ball valve I, pipeline I, and the rotary control device to achieve pressure balance; Step 4: Operate the hydraulic control pry to open the sealing rubber core of the annulus isolation device, close the ball valve I, adjust the valve of the diversion manifold to make it consistent with the valve state of the diversion manifold in the conventional deepwater controlled pressure drilling method, and continue the conventional deepwater controlled pressure drilling work.

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