An underwater wellhead casing annulus pressure monitoring system and monitoring method

Abstract

The present application relates to a kind of underwater wellhead casing annulus pressure monitoring system and monitoring method, system includes annulus pressure measurement physical calibration module and annulus pressure measurement physical calibration module, annulus pressure measurement physical calibration module is set in the casing annulus of underwater wellhead;Magnetic memory detection device is arranged between production casing and production string, and magnetic memory detection device is used to detect annulus pressure measurement physical calibration module, indirectly obtain the pressure data in casing annulus, and the pressure data is transmitted to the receiving end outside underwater well.The system is monitored by annulus pressure measurement physical calibration module and magnetic memory detection device, and the pressure data of casing annulus is characterized, realizes the real-time monitoring of casing annulus pressure, guides production safety management, and provides real pressure data for the design of casing later, is beneficial to real-time optimization of oil and gas field production during the operation system, ensure that casing annulus pressure value is in reasonable range, maintain wellbore structural integrity, avoid excessive design later casing.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction technology, and in particular to a subsea wellhead casing annulus pressure monitoring system and method. Background Technology

[0002] Factors such as temperature variations during oil and gas well production can lead to increased annular pressure. If the annular pressure at the wellhead exceeds the collapse pressure of the inner casing and the rupture pressure of the outer casing, or exceeds the pressure rating of the annular seal assembly and cementing cement, it will seriously threaten the structural integrity of the wellbore. Especially for high-temperature, high-pressure wells, annular pressure monitoring and management are crucial to the integrity of the wellbore structure. However, due to the structural characteristics of subsea wellheads, it is impossible to directly obtain annular pressure data between different casing layers. Therefore, existing technologies typically employ conservative casing design based on theoretically worst-case annular pressure predictions, leading to over-design of casing and resulting in high costs.

[0003] In addition, existing measures to mitigate the increase in casing annular pressure include lowering the cement level below the upper casing shoe, using compressible foam materials, rupture discs, and nitrogen cushions. However, the effectiveness of these measures depends on the rationality of the model assumptions and involves many unpredictable factors, thus failing to provide long-term satisfactory casing annular pressure management measures.

[0004] A prior art real-time monitoring system for casing annulus pressure at an underwater wellhead requires an electromagnetic induction wireless telemetry system within the casing annulus and an underwater acoustic communication system in seawater. Due to the annulus gap being less than 2cm, the annular space is extremely narrow, and the maximum pressure can exceed 70MPa, making it difficult to ensure the smooth installation and long-term effective operation of the electromagnetic induction system. Furthermore, setting up the underwater acoustic communication system requires a long-term underwater power supply and surface vessel resources, resulting in high implementation costs for this disclosed real-time monitoring system for casing annulus pressure. Additionally, real-time monitoring is impossible in harsh sea conditions. Summary of the Invention

[0005] To address one or more of the aforementioned problems, the present invention aims to provide a subsea wellhead casing annulus pressure monitoring system and method. This system monitors casing annulus pressure characterization data using an annulus pressure measurement physical calibration module and a magnetic memory detection device, enabling real-time monitoring of casing annulus pressure. This provides guidance for production safety management and offers accurate pressure data for future casing design, preventing over-design of the casing.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A subsea wellhead casing annulus pressure monitoring system includes: The annulus pressure measurement physical calibration module is installed inside the casing annulus at the underwater wellhead and is used to measure the pressure inside the casing annulus. A magnetic memory detection device is installed between the production casing and the production tubing. The magnetic memory detection device is used to detect the annular pressure measurement physical calibration module, indirectly obtain the pressure data in the annulus of the casing, and transmit the pressure data to the receiving end outside the subsea well.

[0007] Preferably, the casing annulus is annulus formed by the production casing and the technical casing, the technical casing is fitted outside the production casing, and the production casing is fitted outside the production tubing string; the annulus pressure measurement physical calibration module is disposed on the outer wall of the production casing, the magnetic memory detection device is disposed on the outer wall of the production tubing string, and the magnetic memory detection device and the annulus pressure measurement physical calibration module are at the same depth downhole.

[0008] Preferably, the annular pressure measurement physical calibration module includes an outer cylinder, a core column, a calibration spring, and a cover plate. The outer cylinder is connected to the outer wall of the production sleeve. A base is provided inside the outer cylinder. The bottom of the calibration spring is connected to the base inside the outer cylinder. The top of the calibration spring is connected to the bottom of the core column. The cover plate is fastened to the outer cylinder and sealed to it. The cover plate is connected to the top of the core column. The cover plate can drive the core column to move up and down under different pressures, and the core column changes the compression of the calibration spring.

[0009] Preferably, the cover plate is made of a flexible, soft material with a raised top that can deform under different pressures.

[0010] Preferably, the magnetic memory detection device includes a magnetic memory probe and a cable connected thereto. The magnetic memory probe is used to detect the displacement of the core column, the displacement being the compression of the calibration spring. The displacement is transmitted to the receiving end through the cable.

[0011] Preferably, the receiving end is a production monitoring terminal device.

[0012] Preferably, the annular pressure measurement physical calibration module is disposed on the outer wall of the bushing short section, and the bushing short section is connected to the production bushing, so that the annular pressure measurement physical calibration module is located inside the bushing annulus.

[0013] A method for monitoring annular pressure in a subsea wellhead casing, based on any one of the subsea wellhead casing annular pressure monitoring systems described above, includes the following steps: The annulus pressure measurement physical calibration module is installed inside the casing annulus at the underwater wellhead and is lowered to the set depth as the production casing is lowered. The production casing is set and sealed, and the casing annular space is formed by the annular void. The magnetic memory detection device is installed between the production casing and the production tubing, and is lowered into the wellbore along with the production tubing, with the annular pressure measurement physical calibration module at the same depth as the magnetic memory detection device downhole. The annular pressure measurement physical calibration module monitors the pressure inside the casing annulus, and the magnetic memory detection device detects the annular pressure measurement physical calibration module to indirectly obtain the pressure data inside the casing annulus and transmit the pressure data to the receiving end outside the submersible well.

[0014] Preferably, in the step of installing the annulus pressure measurement physical calibration module in the casing annulus at the subsea wellhead, the casing annulus is the annulus formed by the production casing and the technical casing. After the annulus pressure measurement physical calibration module is set on the outer wall of the production casing, the production casing is then lowered into the subsea well.

[0015] Preferably, in the steps of the annular pressure measurement physical calibration module monitoring the pressure inside the casing annulus, the magnetic memory detection device detecting the annular pressure measurement physical calibration module to obtain pressure data inside the casing annulus, and transmitting the pressure data to a receiving end outside the subsea well, The annular pressure measurement physical calibration module includes an outer cylinder, a core column, a calibration spring, and a cover plate. Under different pressures, the cover plate can drive the core column to move up and down, causing the core column to be displaced, thereby changing the compression of the calibration spring and realizing the monitoring of the pressure in the annulus of the bushing. The magnetic memory detection device includes a magnetic memory probe and a cable connected to it. The magnetic memory probe detects the displacement of the core column and transmits the displacement to the receiving end through the cable, thereby enabling the receiving end to monitor the pressure inside the annulus of the bushing.

[0016] The present invention has the following advantages due to the adoption of the above technical solutions: 1. The underwater wellhead casing annulus pressure monitoring system provided by this invention, through an annulus pressure measurement physical calibration module and The magnetic memory detection device monitors the casing annulus pressure characterization data, enabling real-time monitoring of the casing annulus pressure, guiding production safety management, and providing real pressure data for future casing design. This facilitates real-time optimization of operating procedures during oil and gas field production, ensuring that the casing annulus pressure value is within a reasonable range, maintaining the integrity of the wellbore structure, avoiding over-design of future casings, and reducing casing costs.

[0017] 2. The annular pressure monitoring system for underwater wellhead casing provided by this invention has a purely mechanical annular pressure measurement physical calibration module. The mechanical structure requires no electricity and has the ability to monitor the casing annulus pressure in real time for a long period of time. It is suitable for installation in narrow casing annulus spaces and long-term working conditions under high pressure environments, and meets the actual conditions that there are no operating vessels in the sea area where the underwater wellhead is located during the production period. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a water well for installing an annular pressure monitoring system for underwater wellhead casing, according to an embodiment of the present invention.

[0019] Figure 2 This is an enlarged schematic diagram of the location of the underwater wellhead casing annulus pressure monitoring system provided in an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the annular pressure measurement physical calibration module provided in an embodiment of the present invention.

[0021] Figure 4 This is a flowchart of a method for monitoring the annulus pressure of a subsea wellhead casing provided in an embodiment of the present invention.

[0022] Marked in the attached diagram: 1 is the annular pressure measurement physical calibration module, 101 is the outer cylinder, 102 is the core column, 103 is the calibration spring, 104 is the cover plate, 2 is the magnetic memory detection device, 201 is the magnetic memory probe, 202 is the cable, 3 is the sleeve annulus, 4 is the production sleeve, 5 is the production tube column, and 6 is the technical sleeve. Detailed Implementation

[0023] 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.

[0024] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", etc., 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 limitations on this invention.

[0025] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "assembly," "setup," 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.

[0026] This invention provides a subsea wellhead casing annulus pressure monitoring system and method. By monitoring casing annulus pressure characterization data through an annulus pressure measurement physical calibration module and magnetic memory detection device, the system achieves management of casing annulus pressure and provides accurate pressure data for future casing design, thus avoiding over-design of the casing.

[0027] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0028] Example 1 Please refer to the reference. Figure 1 and Figure 2 As shown in the figure, this embodiment provides an underwater wellhead casing annulus pressure monitoring system, including annulus pressure measurement physical calibration module 1 and annulus pressure measurement physical calibration module 2. The annular pressure measurement physical calibration module 1 is installed inside the casing annulus 3 at the underwater wellhead and is used to measure the pressure inside the casing annulus 3. The magnetic memory detection device 2 is installed between the production casing 4 and the production tubing 5. The magnetic memory detection device 2 is used to detect the annulus pressure measurement physical calibration module 1, indirectly obtain the pressure data in the casing annulus 3, and transmit the pressure data to the receiving end outside the subsea well.

[0029] In specific applications, the annular pressure measurement physical calibration module 1 is installed inside the casing annulus 3 at the subsea wellhead to perform long-term real-time calibration of the pressure data of the casing annulus 3. The magnetic memory detection device 2 is an existing technology product with the model number TSC7M16. The magnetic memory detection device 2 can detect the displacement of the core column 102 representing pressure changes in the annular pressure measurement physical calibration module 1 through the side wall of the production casing 4, thereby indirectly obtaining the real-time pressure data inside the casing annulus 3 and transmitting the pressure data to the receiving end outside the subsea well.

[0030] In this embodiment, the casing annulus 3 is the annulus formed by the production casing 4 and the technical casing 6. The technical casing 6 is fitted on the outside of the production casing 4, and the production casing 4 is fitted on the outside of the production tubing string 5. The annulus pressure measurement physical calibration module 1 is set on the outer wall of the production casing 4, and the magnetic memory detection device 2 is set on the outer wall of the production tubing string 5. The magnetic memory detection device 2 and the annulus pressure measurement physical calibration module 1 are at the same depth downhole.

[0031] In specific applications, the annular pressure measurement physical calibration module 1 is lowered into the water to a set depth along with the production casing 3; the magnetic memory detection device 2 is installed on the outer wall of the production tubing 5 and is lowered into the water along with the production tubing 5. The production casing 3 is fitted onto the production tubing 5, so that the annular pressure measurement physical calibration module 1 and the magnetic memory detection device 2 are at the same depth in the well, and the magnetic memory probe 201 of the magnetic memory detection device 2 is placed as close as possible to the inner wall of the production casing 3, so that the magnetic memory probe 201 can more sensitively detect the displacement changes of the core column 102 inside the annular pressure measurement physical calibration module 1.

[0032] Please refer to the reference. Figure 3 As shown, in this embodiment, the annular pressure measurement physical calibration module 1 includes an outer cylinder 101, a core column 102, a calibration spring 103, and a cover plate 104. The outer cylinder 101 is connected to the outer wall of the production sleeve 4. The top of the outer cylinder 101 is open, and a base is provided inside the cylinder body of the outer cylinder 101. The bottom of the calibration spring 103 is connected to the base inside the cylinder body of the outer cylinder 101, and the top of the calibration spring 103 is connected to the bottom of the core column 102. The cover plate 104 is fastened to the top opening of the outer cylinder and sealed to it. The cover plate 104 is connected to the top of the core column 102. The cover plate 104 can drive the core column 102 to move up and down under different pressures. The core column 102 changes the compression of the calibration spring 103. The compression is used to characterize the annular pressure of the sleeve.

[0033] In practical applications, the outer cylinder 101 is cylindrical, the core column 102 is a steel cylinder, and the calibration spring 103 is a pressure-calibrated spring whose compression corresponds to the pressure change. The calibration spring 103 is installed inside the outer cylinder 101. Its initial state represents the initial pressure value within the annulus 3 of the bushing, and the change in the compression of the calibration spring 103 represents the pressure change within the annulus 3. The compression of the calibration spring 103 is also the displacement of the core column 102 relative to its initial position. When the magnetic memory detection device 2 detects the displacement of the core column 102, it can indirectly obtain the pressure change within the annulus 3 of the bushing. Combined with the initial pressure value within the annulus 3, the actual pressure data within the annulus 3 can be determined. The magnetic memory detection device 2 can monitor the displacement change of the core column 102 in real time. Therefore, the external receiving system can monitor the pressure data within the annulus 3 of the bushing in real time, achieving pressure management within the annulus 3 and providing accurate pressure data for future bushing design, avoiding over-design of the bushing.

[0034] In this embodiment, the cover plate 104 is made of a flexible, soft material. Under different pressure differences inside and outside the physical calibration module, the top of the cover plate 104 can produce different deformations. The deformation changes the position of the core column 102, thereby changing the compression of the calibration spring. Specifically, the top of the cover plate 104 is convex, which can deform under different internal and external pressure differences. The annular pressure outside the physical calibration module acts directly on the core column 102, causing the core column 102 to displace.

[0035] In this embodiment, the magnetic memory detection device 2 includes a magnetic memory probe 201 and a cable 202 connected thereto. The magnetic memory probe 201 is used to detect the displacement of the core 102, which is the compression of the calibration spring. The displacement is transmitted to the receiving end through the cable 202.

[0036] In practical applications, cable 202 extends upward along the gap between production casing 4 and production tubing 5, and connects to the receiving end after exiting the well. Transmitting pressure data through cable 202 can ensure the timeliness and stability of data transmission.

[0037] In this embodiment, the receiving end is a production monitoring terminal device. The production monitoring terminal device receives the pressure value in the casing annulus 3 transmitted by the magnetic memory detection device 2 and can display it to the management personnel. This facilitates the management personnel to manage the pressure in the casing annulus 3 and can guide production management based on pressure changes, ensuring wellbore safety and improving production safety.

[0038] In this embodiment, the annular pressure measurement physical calibration module 1 is set on the outer wall of the bushing short section, and the bushing short section is connected to the production bushing 4, so that the annular pressure measurement physical calibration module 1 is located in the annulus 3 of the bushing.

[0039] In practical applications, the annular pressure measurement physical calibration module 1 needs to be installed at a designated position on the production sleeve 4. The manufacturer of the production sleeve 4 can directly manufacture a sleeve short section with the annular pressure measurement physical calibration module 1 installed in the factory, and connect the sleeve short section to the production sleeve 4 to reduce the amount of on-site installation work.

[0040] Example 2 Please refer to the reference. Figure 4 As shown, the underwater wellhead casing annulus pressure monitoring system provided in this embodiment monitors the casing annulus pressure based on the system provided in Embodiment 1. The monitoring method includes the following steps: S01, the annulus pressure measurement physical calibration module 1 is installed in the casing annulus 3 at the underwater wellhead and is lowered to the set depth as the production casing 4 is lowered; S02, the production casing 4 is set and sealed, and the casing annulus 3 forms an annular sealed space; S03, the magnetic memory detection device 2 is installed between the production casing 4 and the production tubing 5, and is lowered into the wellbore along with the production tubing 5, and the magnetic memory detection device 2 and the annular pressure measurement physical calibration module 1 are at the same depth downhole. S04, the annular pressure measurement physical calibration module 1 monitors the pressure inside the casing annulus 3, the magnetic memory detection device 2 detects the annular pressure measurement physical calibration module 1, obtains the pressure data inside the casing annulus 3, and transmits the pressure data to the receiving end outside the submersible well.

[0041] In specific applications, the magnetic memory detection device 2 is installed on the outer wall of the production tubing 5 and is lowered along with the production tubing 5. The casing annulus 3 is the annulus formed between the production casing 4 and the technical casing 6. After the annulus pressure measurement physical calibration module 1 is installed on the outer wall of the production casing 4, the production casing 4 is then placed outside the production tubing 5 and lowered so that the annulus pressure measurement physical calibration module 1 and the magnetic memory detection device 2 are at the same depth in the well. At this time, the magnetic memory detection device 2 is located between the production casing 4 and the production tubing 5. The magnetic memory probe 201 of the magnetic memory detection device 2 can be as close as possible to the inner wall of the production casing 4 so that it can more accurately sense the displacement generated by the core column 102.

[0042] The annular pressure measurement physical calibration module 1 is located within the annulus 3 between the production casing 4 and the technical casing 6. With the setting of the production casing 4, the top of the production casing 4 and the top of the technical casing 6 are sealed together. As the production casing 4 sets, the annulus 3 is filled with liquid, forming a closed annular space. This closed space exists throughout the entire production life of the oil and gas well, potentially for decades, until the well is abandoned and the casing is cut, at which point the annular space opens. Therefore, the annular pressure measurement physical calibration module 1, made of mechanical components, requires no power supply and can be used long-term within the annulus 3. The annular pressure measurement physical calibration module 1 monitors the pressure within the annulus 3. The magnetic memory detection device 2 detects the annular pressure measurement physical calibration module 1, acquiring the pressure data within the annulus 3 and transmitting the pressure data to a receiver outside the subsea well. This enables management of the annular pressure and provides accurate pressure data for future casing design, preventing over-design of the casing.

[0043] In step S04, the annular pressure measurement physical calibration module 1 includes an outer cylinder 101, a core column 102, a calibration spring 103, and a cover plate 104. Under different pressures, the cover plate 104 can drive the core column 102 to move up and down, causing the core column 102 to be displaced, thereby changing the compression of the calibration spring 103 and realizing the monitoring of the pressure in the annular space 3 of the sleeve. The magnetic memory detection device 2 includes a magnetic memory probe 201 and a cable 202 connected thereto. The magnetic memory probe 201 detects the displacement of the core 102 and transmits the displacement to the receiving end through the cable 202, so as to realize the monitoring of the pressure in the annulus of the bushing at the receiving end.

[0044] In this embodiment, when the underwater wellhead casing annulus pressure monitoring system is used, the annulus pressure measurement physical calibration module 1 is set with an initial pressure value. When the pressure in the casing annulus 3 changes, the core column 102 undergoes a displacement change. The magnetic memory detection device 2 senses the displacement change of the core column 102. The compression of the calibration spring 103 is proportional to the pressure change. The magnetic memory detection device 2 can then determine the pressure change. Combined with the set initial value, the actual pressure value in the casing annulus 3 can be obtained.

[0045] 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 subsea wellhead casing annulus pressure monitoring system, characterized in that, include: The annular pressure measurement physical calibration module is installed inside the casing annulus at the underwater wellhead and is used to measure the pressure inside the casing annulus. A magnetic memory detection device is installed between the production casing and the production tubing. The magnetic memory detection device is used to detect the annular pressure measurement physical calibration module, indirectly obtain the pressure data in the annulus of the casing, and transmit the pressure data to the receiving end outside the submersible well. The casing annulus is formed by the production casing and the technical casing. The technical casing is fitted outside the production casing, and the production casing is fitted outside the production tubing string. The annulus pressure measurement physical calibration module is installed on the outer wall of the production casing, and the magnetic memory detection device is installed on the outer wall of the production tubing string. The magnetic memory detection device and the annulus pressure measurement physical calibration module are at the same depth downhole. The annular pressure measurement physical calibration module includes an outer cylinder, a core column, a calibration spring, and a cover plate. The outer cylinder is connected to the outer wall of the production casing. A base is provided inside the outer cylinder. The bottom of the calibration spring is connected to the base inside the outer cylinder. The top of the calibration spring is connected to the bottom of the core column. The cover plate is fastened to the outer cylinder and sealed to it. The cover plate is connected to the top of the core column. The cover plate can drive the core column to move up and down under different pressures. The core column changes the compression of the calibration spring. The compression is used to characterize the annular pressure of the casing. The compression of the calibration spring is also the displacement of the core column relative to its initial position. When the magnetic memory detection device detects the displacement of the core column, it can indirectly obtain the change in pressure within the annulus of the bushing. Combined with the initial value of the pressure within the annulus of the bushing, the actual pressure data within the annulus of the bushing can be determined. The magnetic memory detection device can monitor the displacement change of the core column in real time, and the external receiving system can monitor the pressure data within the annulus of the bushing in real time, thereby achieving management of the pressure within the annulus of the bushing and providing accurate pressure data for future bushing design, avoiding over-design of the bushing. The magnetic memory detection device includes a magnetic memory probe and a cable connected thereto. The magnetic memory probe is used to detect the displacement of the core column. The displacement is the compression of the calibration spring. The displacement is transmitted to the receiving end through the cable.

2. The underwater wellhead casing annulus pressure monitoring system according to claim 1, characterized in that, The cover plate is made of a flexible, soft material with a raised top that can deform under different pressures.

3. The underwater wellhead casing annulus pressure monitoring system according to claim 2, characterized in that, The receiving end is a production monitoring terminal device.

4. The underwater wellhead casing annulus pressure monitoring system according to claim 1, characterized in that, The annular pressure measurement physical calibration module is set on the outer wall of the bushing short section, which is connected to the production bushing, so that the annular pressure measurement physical calibration module is located in the annulus of the bushing.

5. A method for monitoring the annulus pressure of a subsea wellhead casing, characterized in that, The underwater wellhead casing annulus pressure monitoring system, based on any one of claims 1 to 4, comprises the following steps: The annular pressure measurement physical calibration module is installed inside the casing annulus at the underwater wellhead and is lowered to the set depth as the production casing is lowered. The production casing is set and sealed, and the casing annular space is formed by the annular space. The magnetic memory detection device is installed between the production casing and the production tubing, and is lowered into the wellbore along with the production tubing, with the annular pressure measurement physical calibration module at the same depth as the magnetic memory detection device downhole. The annular pressure measurement physical calibration module monitors the pressure inside the casing annulus, and the magnetic memory detection device detects the annular pressure measurement physical calibration module to indirectly obtain the pressure data inside the casing annulus and transmit the pressure data to the receiving end outside the submersible well.

6. The method for monitoring the annulus pressure of a subsea wellhead casing according to claim 5, characterized in that, In the step of installing the annulus pressure measurement physical calibration module in the casing annulus at the subsea wellhead, the casing annulus is the annulus formed by the production casing and the technical casing. After the annulus pressure measurement physical calibration module is set on the outer wall of the production casing, the production casing is then lowered into the subsea well.

7. The method for monitoring the annulus pressure of a subsea wellhead casing according to claim 5, characterized in that, In the steps of the annular pressure measurement physical calibration module monitoring the pressure within the casing annulus, the magnetic memory detection device detecting the annular pressure measurement physical calibration module to acquire pressure data within the casing annulus, and transmitting the pressure data to a receiving end outside the submersible well,... The annular pressure measurement physical calibration module includes an outer cylinder, a core column, a calibration spring, and a cover plate. Under different pressures, the cover plate can drive the core column to move up and down, causing the core column to be displaced, thereby changing the compression of the calibration spring and realizing the monitoring of the pressure in the annulus of the bushing. The magnetic memory detection device includes a magnetic memory probe and a cable connected to it. The magnetic memory probe detects the displacement of the core column and transmits the displacement to the receiving end through the cable, thereby enabling the receiving end to monitor the pressure inside the annulus of the bushing.

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