High-temperature and high-pressure wellbore tubular column corrosion monitoring system and monitoring method

Abstract

The invention provides a high-temperature and high-pressure wellbore tubular column corrosion monitoring system and monitoring method. The system comprises a monitoring probe (1), a flow guide cap (2), a left shell seat (3), a battery (4), a circuit board (5), a compensation test piece (6), a right shell seat (8), a protective cover (9), a main shell (14), a communication port (15), a pipe clamp clip (18), a fan-shaped thin-wall keel (13), a protective cover (20) and a vent groove (22). The invention further relates to a monitoring method of the system. Through unique sealing design, combination of the embedded probe and the compensation test piece and accurate control of mutual excitation of direct current / alternating current, accurate monitoring in severe environments such as high temperature and high pressure is realized, the reliability of the system is effectively improved, and the service life of the system is effectively prolonged. The defect that the system is difficult to adapt to severe working conditions is overcome, the monitoring precision and the durability of the system are greatly improved, and the system is of great significance to improvement of oil and gas field exploitation efficiency and safety.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas wellbore pipe string corrosion monitoring, and in particular relates to a high-temperature and high-pressure wellbore pipe string corrosion monitoring system and a monitoring method. Background Art

[0002] In the process of modern oil and gas field development, oil and gas pipelines are important infrastructures, and their safety and reliability directly affect the smooth transportation of oil and gas resources and the economic benefits of enterprises. During the long-term service of pipelines, due to the corrosiveness of the internal medium, the influence of external environmental factors and changes in operating conditions, pipelines often suffer from corrosion to varying degrees. These corrosions will not only reduce the carrying capacity of the pipeline, increase the risk of leakage and rupture, but also cause serious safety accidents and environmental pollution problems. Therefore, how to effectively monitor pipeline corrosion and ensure the safe operation of pipelines has become a major issue facing the oil and gas industry.

[0003] At present, the corrosion monitoring technologies widely used in the industry mainly include the corrosion coupon weight loss method, the online resistance probe method, the linear polarization method, etc. Although these technologies can meet the needs of corrosion monitoring to a certain extent, there are still application defects in practical applications. For example, the corrosion coupon weight loss method and the linear polarization method require regular sampling or manual measurement, which cannot achieve real-time online monitoring, and the monitoring frequency is low, making it difficult to detect the intensification of corrosion in time. Although the online resistance probe method can achieve continuous monitoring, its reliability and stability are limited in harsh environments such as high temperature and high pressure. In addition, in the harsh underground environment of high temperature and high pressure, conventional sensor materials and packaging materials may degrade in performance, resulting in failure of monitoring equipment. Signal transmission is then interfered with, affecting the accuracy and reliability of monitoring data.

[0004] In view of the above technical challenges, the existing corrosion monitoring technology has obvious deficiencies in practical applications, especially in the field of corrosion monitoring of high-temperature and high-pressure wellbore tubulars. Therefore, the development of a new type of high-temperature and high-pressure wellbore tubular corrosion monitoring system can effectively cope with these challenges, which has great practical significance and application value for ensuring the safe operation of oil and gas pipelines, reducing economic losses and environmental pollution. The present invention aims to propose a solution to overcome the deficiencies of the existing technology and meet the actual needs of high-temperature and high-pressure wellbore tubular corrosion monitoring. Summary of the invention

[0005] The purpose of the present invention is to provide a high-temperature and high-pressure wellbore pipe corrosion monitoring system and a monitoring method.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention relates to a high-temperature and high-pressure wellbore pipe column corrosion monitoring system, comprising a monitoring probe 1, a guide cap 2, a left housing seat 3, a battery 4, a circuit board 5, a compensation test piece 6, a right housing seat 8, a protective cover 9, a main housing 14, a communication port 15, a pipe clamp clip 18, a fan-shaped thin-walled keel 13, a protective cover 20, and a ventilation groove 22;

[0008] The monitoring probe 1 converts the physical changes caused by the corrosion of the object to be tested into electrical signals, which are then transmitted to the circuit board 5 for processing;

[0009] The guide cap 2 is fixed to the upper left end of the left housing seat 3, and the protective cover 9 is fixed to the upper right end of the right housing seat 8;

[0010] The battery 4, the circuit board 5, and the compensation test piece 6 are fixed on the fan-shaped thin-walled keel 13; and the insulating component is made of polytetrafluoroethylene;

[0011] Battery 4 provides power to the entire system;

[0012] The circuit board 5 includes a signal processing circuit, a microcontroller and a data storage module; the circuit board 5 receives the signal from the monitoring probe 1, amplifies, filters and digitizes it, and then stores or sends the data through the communication port 15;

[0013] The compensation test piece 6 is used in conjunction with the monitoring probe 1;

[0014] The main housing 14 is cylindrical, and the monitoring probe 1 is connected to the left housing seat 3;

[0015] The four leads for measuring the corrosion of the oil pipe are led out from the glass high-voltage isolation terminals 12 on the lower sides of the left housing seat 3 and the right housing seat 8. The monitoring device is a fully enclosed hollow body except for the communication port 15 on the right side of the right housing seat 8;

[0016] The high temperature and high pressure wellbore tubular string corrosion monitoring system is fixed on the oil well tubular string by two pipe clamps 18 and fixed by oil pipe hoop 19. The material of the connection between the pipe clamp 18 and the oil well tubular string is thermosetting material, and a layer of silicone rubber is coated on the metal surface connected by the pipe clamp 18 to prevent crevice corrosion.

[0017] Preferably, the monitoring probe 1 comprises two parts, a mosaic probe and an annulus probe 21; wherein, the probe of the mosaic probe is embedded in a standard oil well tubing string as a test specimen; a compensation specimen 6 is fixed on the other side of the oil pipe and insulated from the oil pipe to ensure that the test specimen and the compensation specimen are in the same temperature environment, thereby ensuring the accuracy of the measurement results.

[0018] Preferably, there are several test strips, which are connected in series to ensure the consistency and efficiency of the measurement.

[0019] Preferably, the excitation signal generated by the circuit board 5 is input from one end of the compensation test piece 6 and is led out from the right terminal of the monitoring probe 1; the excitation response signal is emitted from the right terminal of the fixing seat and the lower terminal of the glass aviation plug 7. The excitation signal is a direct current, and the change in the wall thickness of the oil well pipe and the change in the corrosion rate are calculated by the change in the excitation signal.

[0020] Preferably, the excitation signal is a direct current, and the alternating current excitation signal is obtained by: obtaining the direct current signal through debugging, applying it to both ends of the serial test piece through a signal transformer, and the direct current controls the current on and off through a field effect tube (temperature -55°C to 155°C) switch.

[0021] In order to further illustrate the functions of the various components of the system of the present invention, the following explanation is made:

[0022] The monitoring probe 1 is used to directly contact the fluid in the well and detect the corrosion of the pipe string through electrochemical reaction or resistance change; the monitoring probe 1 converts the physical changes caused by corrosion into electrical signals, which are then transmitted to the circuit board 5 for processing.

[0023] The guide cap 2 is fixed at the front end of the system to help adjust the flow direction of the fluid, ensure uniform distribution of the fluid, reduce the impact of turbulence on the monitoring probe 1, and improve the accuracy of the measurement.

[0024] The left housing seat 3 provides space for installing the monitoring probe 1 and other internal components. The left housing seat 3 is connected to the guide cap 2 to form the front end of the system.

[0025] The battery 4 supplies power to the entire system, ensuring that the system can operate autonomously for a long time without an external power source.

[0026] The circuit board 5 includes a signal processing circuit, a microcontroller and a data storage module; the circuit board 5 receives the signal from the monitoring probe, amplifies, filters and digitizes it, and then stores or sends the data through the communication port 15.

[0027] The compensation test piece 6 is used in conjunction with the monitoring probe 1 to compensate for the influence of environmental factors (such as temperature changes) on the measurement results to ensure the accuracy of the measurement results. The compensation test piece 6 and the monitoring probe 1 are in the same temperature environment.

[0028] The glass aviation plug 7 provides a safe and reliable electrical connection method for the system, which is used to transmit data or power the system.

[0029] The right housing seat 8 constitutes the rear structure of the system, provides installation space for internal components, and includes a communication port 15 for communicating with ground equipment.

[0030] The protective cover 9 is used to protect the internal components of the system from the harsh environment in the well (such as high temperature, high pressure and corrosive fluid).

[0031] The pressing block lead 10 is used to connect the monitoring probe 1 or other components to the circuit board 5 to ensure reliable transmission of signals.

[0032] The high temperature filling glue 11 is used to fill certain parts of the system to prevent the fluid in the well from penetrating, and at the same time has high temperature resistance to ensure the sealing effect.

[0033] The isolation terminal 12 is used to isolate the internal circuit from the external environment to prevent current leakage and ensure the safe operation of the system.

[0034] The thin-walled tube keel 13 serves as a supporting structure, carries the internal components of the system, and provides good insulation performance to prevent electrical interference.

[0035] The main housing 14 is a cylindrical structure and is the main shell of the system, providing a closed environment to protect the internal components from external conditions.

[0036] The plug 16 is used to close the opening of the system, maintain the sealing of the system, and prevent the fluid in the well from entering.

[0037] The oil pipe short circuit 17 is used to connect the system with the oil pipe, ensuring that the system can be correctly installed inside the oil pipe while reducing the impact on the flow of fluid in the oil pipe.

[0038] The pipe clamp clip 18 is made of thermosetting material and is used to fix the system on the oil pipe string. The connection between the pipe clamp clip 18 and the oil pipe string is coated with silicone rubber to prevent crevice corrosion.

[0039] The oil pipe clamp 19 is used in conjunction with the pipe clamp clip 18 to enhance the connection strength between the system and the oil pipe string, thereby ensuring stable operation of the system underground.

[0040] The protective cover 20 is used to protect certain parts of the system from mechanical damage.

[0041] The annular probe 21 works together with the inlaid probe to monitor the corrosion condition of the outside of the oil pipe string. The annular probe 21 detects the corrosion degree through electrochemical reaction or resistance change.

[0042] The ventilation groove 22 is used to achieve internal and external gas exchange of the system, balance the pressure difference, and prevent damage caused by pressure changes.

[0043] The working principle of the present invention is as follows:

[0044] (1) Installation and fixing: Fix the system to the oil pipe string through the pipe clamp 18 and the oil pipe clamp 19. The guide cap 2 is installed on the left shell seat 3 to ensure uniform distribution of the fluid;

[0045] (2) Signal acquisition: The monitoring probe 1 and the annulus probe 21 are in contact with the fluid in the well to detect the corrosion of the tubing string; the monitoring probe 1 converts the physical changes caused by corrosion into electrical signals through electrochemical reactions or resistance changes;

[0046] (3) Signal transmission: The electrical signal is transmitted to the circuit board 5 through the pressing block lead 10, and the signal processing circuit on the circuit board 5 amplifies, filters and digitizes the signal;

[0047] (4) Data processing and storage: The processed data is stored in the storage module of the circuit board 5 and transmitted to the ground control system through the communication port 15;

[0048] (5) Environmental compensation: The compensation test piece 6 and the monitoring probe 1 are placed in the same temperature environment, and the influence of environmental factors on the measurement results is eliminated by comparing the changes of the compensation test piece 6;

[0049] (6) Power supply: Battery 4 provides power to the entire monitoring device, ensuring that the system can operate autonomously for a long time without external power supply;

[0050] (7) Data transmission: Monitoring data can be transmitted to the ground control system in real time through communication port 15, supporting remote monitoring and data analysis;

[0051] (8) Maintenance and recovery: After completing a maintenance cycle, the entire system can be returned to the surface along with the oil pipe, the pipe clamp clip 18 and the oil pipe clamp 19 can be opened, and the system can be brought back to the work area to extract data and analyze it.

[0052] The present invention also relates to a monitoring method of the aforementioned high temperature and high pressure wellbore pipe string corrosion monitoring system, comprising the following steps:

[0053] Step 1: Lower the system into the well to set the monitoring area and securely assemble it by snap-fitting;

[0054] Step 2: Apply an excitation signal with a continuous frequency change to the monitoring area based on the current limiting resistor, and use the control switch to realize the synchronous application of the excitation signal, and use the analog switch to select the measurement channel, based on the common primary and secondary signal amplification circuits and analog-to-digital conversion circuits; the analog-to-digital conversion circuit uses a high-precision, wide dynamic range insulated gate bipolar transistor measurement chip, and can still save data after power failure, and can be used in extreme environments (-55 ~ 210 ° C);

[0055] Step 3: As the corrosion time progresses, the thickness of the test piece continues to decrease, and the resistance of the test piece also continues to decrease. The thinning amount and the resistance of the test piece show a linear relationship. The corrosion rate calculated based on the change in pipe wall thickness measured by the probe represents the corrosion rate of the target pipe string. The resistance calculation of the test piece probe is shown in formula (1):

[0056]

[0057] In formula (1), Ω is the resistance of the test piece probe, ρ is the resistivity of the test piece probe material, Ω·m; L is the length of the test piece probe, mm; S is the cross-sectional area of ​​the test piece probe, mm 2 ; R and r are the outer diameter and inner diameter of the test piece, mm.

[0058] The calculation of corrosion depth is shown in formula (2):

[0059]

[0060] In formula (2): 0 is the original radius of the test specimen, R 0 is the resistance value before corrosion; R i is the resistance value after corrosion;

[0061]

[0062] In formula (3), T 2 and T 1 is the time difference between the two measurements; H 2 and H 1 is the difference between the two corrosion depth measurements;

[0063] Step 4: After completing a maintenance cycle, the oil pipe is returned to the surface, the pipe clamp clip 18 is opened, and the data is taken back to the work area to be extracted and analyzed.

[0064] The present invention has the following advantages:

[0065] (1) The high-temperature and high-pressure wellbore tubular corrosion monitoring system of the present invention can accurately monitor the corrosion of the wellbore tubular under a high-temperature and high-pressure environment. The unique sealing design ensures the reliability of the system and can maintain stable operation under extreme conditions, thereby effectively extending the service life of the system.

[0066] (2) The high-temperature and high-pressure wellbore tubular corrosion monitoring system of the present invention adopts a combination of an inlaid probe and an annulus probe, which can not only monitor the corrosion condition of the inner wall of the tubular in real time, but also eliminate the influence of external environmental factors on the measurement results by setting a compensation test piece, thereby improving the accuracy of the measurement data.

[0067] (3) The high-temperature and high-pressure wellbore tubular corrosion monitoring system of the present invention utilizes thermosetting materials and silicone rubber coating technology to solve the problem of crevice corrosion that is prone to occur at the connection points of traditional clips, thereby enhancing the anti-corrosion performance of the entire monitoring system and ensuring long-term working stability.

[0068] (4) The high-temperature and high-pressure wellbore tubular corrosion monitoring system of the present invention has a compact and reasonable overall structural design. All core components, such as batteries and circuit boards, are integrated on a fan-shaped thin-walled keel and insulated with polytetrafluoroethylene material, which simplifies the assembly process and enhances the system's anti-interference ability.

[0069] (5) The high-temperature and high-pressure wellbore tubular corrosion monitoring system of the present invention has an ingenious design of the excitation signal that uses a combination of direct current and alternating current excitation. By precisely controlling the changes in the excitation signal, it is possible to effectively detect changes in the wall thickness and corrosion rate of the oil well tubular, thereby providing a reliable basis for timely maintenance.

[0070] (6) The high-temperature and high-pressure wellbore tubing corrosion monitoring system and monitoring method provided by the present invention not only overcome the defect of the prior art that it is difficult to adapt to harsh working conditions, but also greatly improve the monitoring accuracy and durability of the system, which is of great significance for improving the efficiency and safety of oil and gas field exploitation. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 A schematic diagram of the internal structure of the high-temperature and high-pressure wellbore pipe corrosion monitoring system of the present invention;

[0072] Figure 2 A schematic diagram of the monitoring working principle of the high-temperature and high-pressure wellbore pipe corrosion monitoring system of the present invention;

[0073] Figure 3 It is a schematic diagram of the partial structure of the high-temperature and high-pressure wellbore pipe string corrosion monitoring system of the present invention;

[0074] Figure 4 This is a corrosion loss monitoring diagram of the high-temperature and high-pressure wellbore pipe string corrosion monitoring system of the present invention at 4200m underground;

[0075] Figure 5 This is a corrosion loss monitoring diagram of the high-temperature and high-pressure wellbore pipe corrosion monitoring system of the present invention at 5000m underground;

[0076] The attached drawings are marked as follows: 1—monitoring probe; 2—flow guide cap; 3—left shell seat; 4—battery; 5—circuit board; 6—compensation test piece; 7—glass aviation plug; 8—right shell seat; 9—protective cover; 10—pressure block lead: 11—high temperature filling glue; 12—isolation terminal; 13—thin-walled pipe keel; 14—main shell; 15—communication port; 16—sealing; 17—oil pipe short circuit; 18—pipe clamp; 19—oil pipe clamp; 20—protective cover; 21—annulus probe; 22—vent groove. DETAILED DESCRIPTION

[0077] The present invention is described in detail below in conjunction with specific embodiments. It should be noted that the following embodiments are only further descriptions of the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0078] Example

[0079] This embodiment relates to a high temperature and high pressure wellbore pipe corrosion monitoring system. Figure 1 and Figure 3 As shown, it includes a monitoring probe 1, a guide cap 2, a left housing seat 3, a battery 4, a circuit board 5, a compensation test piece 6, a right housing seat 8, a protective cover 9, a main housing 14, a communication port 15, a pipe clamp 18, a fan-shaped thin-walled keel 13, a protective cover 20, and a ventilation groove 22;

[0080] The monitoring probe 1 converts the physical changes caused by the corrosion of the object to be tested into electrical signals, which are then transmitted to the circuit board 5 for processing;

[0081] The guide cap 2 is fixed to the upper left end of the left housing seat 3, and the protective cover 9 is fixed to the upper right end of the right housing seat 8;

[0082] The battery 4, the circuit board 5, and the compensation test piece 6 are fixed on the fan-shaped thin-walled keel 13; and the insulating component is made of polytetrafluoroethylene;

[0083] Battery 4 provides power to the entire system;

[0084] The circuit board 5 includes a signal processing circuit, a microcontroller and a data storage module; the circuit board 5 receives the signal from the monitoring probe 1, amplifies, filters and digitizes it, and then stores or sends the data through the communication port 15;

[0085] The compensation test piece 6 is used in conjunction with the monitoring probe 1;

[0086] The main housing 14 is cylindrical, and the monitoring probe 1 is connected to the left housing seat 3;

[0087] The four leads for measuring the corrosion of the oil pipe are led out from the glass high-voltage isolation terminals 12 on the lower sides of the left housing seat 3 and the right housing seat 8. The monitoring device is a fully enclosed hollow body except for the communication port 15 on the right side of the right housing seat 8;

[0088] The high temperature and high pressure wellbore tubular string corrosion monitoring system is fixed on the oil well tubular string by two pipe clamps 18 and fixed by oil pipe hoop 19. The material of the connection between the pipe clamp 18 and the oil well tubular string is thermosetting material, and a layer of silicone rubber is coated on the metal surface connected by the pipe clamp 18 to prevent crevice corrosion.

[0089] The monitoring probe 1 comprises two parts: an inlaid probe and an annulus probe 21; wherein, the probe of the inlaid probe is inlaid into a standard oil well pipe string as a test piece; a compensation piece 6 is fixed on the other side of the oil pipe and insulated from the oil pipe to ensure that the test piece and the compensation piece are in the same temperature environment, thereby ensuring the accuracy of the measurement results.

[0090] There are several test pieces, which are connected in series to ensure the consistency and efficiency of the measurement.

[0091] The excitation signal generated by the circuit board 5 is input from one end of the compensation test piece 6 and is led out from the right terminal of the monitoring probe 1; the excitation response signal is sent from the right terminal of the fixing seat and the lower terminal of the glass aviation plug 7. The excitation signal is a direct current, and the change in the wall thickness of the oil well pipe and the change in the corrosion rate are calculated by the change in the excitation signal.

[0092] The excitation signal is a direct current, and the alternating current excitation signal is obtained by debugging the direct current signal, applied to both ends of the serial test piece through a signal transformer, and the direct current is controlled by a field effect tube (temperature -55°C to 155°C) switch to switch the current on and off.

[0093] The wellbore probe consists of an inlaid wellbore probe and an annulus probe. The accuracy of the probe and hanging plate test data is achieved by making a simulated inlaid wellbore probe and a simulated annulus probe and coupling the two together. The 110,000 mg / L formation produced fluid is used as the experimental medium, the test cycle is set to 15 days, the experimental temperature and pressure are set to 120℃ and 150℃ based on the different wellbore depths, and the pressure is set to 43.7MPa and 62.0MPa based on the different wellbore depths. After the experiment, the long-term corrosion monitoring data of the wellbore is collected and analyzed, see Figure 2 As shown, the specific test steps are as follows:

[0094] (1) Select N80Q steel as the simulated oil pipe, and connect two measuring electrodes and two applying electrodes on the surface of the oil pipe steel;

[0095] (2) Both ends of the simulated oil pipe adopt an internal thread sealing structure, and 110,000 mg / L of formation produced fluid is injected into it, and three N80Q steel sheets are fixed with a PEEK temperature-resistant clamp;

[0096] (3) connecting the simulated annulus probe to the simulated embedded wellbore probe circuit board, fixing the simulated annulus probe on the experimental variable frame, adding formation produced fluid into the experimental chamber to be tested, and ensuring that the probe is completely immersed in the produced fluid;

[0097] (4) Plug the data converter into the communication port, and connect the data converter to the notebook via the USB communication cable;

[0098] (5) After setting the measurement parameters on the software, disconnect the data converter from the communication port, insert the short-circuit cap into the communication port, turn on the power and start the measurement. The test is divided into two groups, each group of test is 72 hours.

[0099] (6) After the test, remove the short-circuit cap, connect the data converter, USB communication cable and notebook, and analyze the test data.

[0100] from Figure 4 , Figure 5 It can be concluded from Table 1 (N80Q steel probe corrosion rate and coupon corrosion rate difference analysis table) that the corrosion coupon is slightly corroded as a whole, the coupon corrosion rate is about 0.0633mm / a, the overall thinning amount at 4200m is about 620μm, and the error between the coupon corrosion rate and the probe monitoring corrosion rate is about 2.53%. The corrosion thinning amount of the wellbore corrosion probe test at 6000m underground is about 660μm, and the error between the coupon corrosion rate and the probe monitoring corrosion rate is about 4.68%. Therefore, the probe corrosion rate is relatively consistent with the coupon corrosion rate, that is, the data of a high-temperature and high-pressure wellbore tubular corrosion monitoring system is accurate and reliable, which can meet the requirements of wellbore corrosion monitoring in harsh environments, and provides an effective solution for corrosion monitoring of the casing annulus in harsh oilfield produced water systems.

[0101] Table 1

[0102]

[0103] The present invention realizes real-time and accurate monitoring of wellbore tubular corrosion under high temperature and high pressure environment through unique sealing design, combination of embedded probe and compensation test piece, and precise control of DC current excitation signal, thereby effectively improving the reliability and service life of the system.

[0104] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which will not affect the essence of the present invention.

Claims

1. A high temperature and high pressure wellbore pipe corrosion monitoring system, characterized in that: It comprises a monitoring probe (1), a flow guide cap (2), a left housing seat (3), a battery (4), a circuit board (5), a compensation test piece (6), a right housing seat (8), a protective cover (9), a main housing (14), a communication port (15), a pipe clamp (18), a fan-shaped thin-walled keel (13), a protective cover (20), and a ventilation groove (22); The monitoring probe (1) converts the physical changes caused by the corrosion of the object to be tested into electrical signals, and then transmits the signals to the circuit board (5) for processing; The guide cap (2) is fixed to the upper left end of the left housing seat (3), and the protective cover (9) is fixed to the upper right end of the right housing seat (8); The battery (4), the circuit board (5) and the compensation test piece (6) are fixed on the fan-shaped thin-walled keel (13); The battery (4) provides power to the entire system; The circuit board (5) comprises a signal processing circuit, a microcontroller and a data storage module; the circuit board (5) receives the signal from the monitoring probe (1), performs amplification, filtering and digitization processing, and then stores or sends the data through the communication port (15); The compensation test piece (6) is used in conjunction with the monitoring probe (1); The main housing (14) is cylindrical, and the monitoring probe (1) is connected to the left housing seat (3); The system is fixed on the oil well pipe string by a pipe clamp (18) and fixed by a pipe hoop (19). The material of the connection between the pipe clamp (18) and the oil well pipe string is a thermosetting material, and a layer of silicone rubber is coated on the metal surface connected by the pipe clamp (18).

2. The high temperature and high pressure wellbore pipe string corrosion monitoring system according to claim 1, characterized in that: The monitoring probe (1) comprises two parts, an inlaid probe and an annulus probe (21); wherein the probe of the inlaid probe is inlaid into a standard oil well pipe string as a test piece; and a compensation piece (6) is fixed on the other side of the oil pipe and insulated from the oil pipe.

3. The high temperature and high pressure wellbore pipe string corrosion monitoring system according to claim 2, characterized in that: There are several test strips, which are connected in series.

4. The high temperature and high pressure wellbore pipe string corrosion monitoring system according to claim 1, characterized in that: The excitation signal generated by the circuit board (5) is input from one end of the compensation test piece (6) and is led out from the right terminal of the monitoring probe (1); the excitation response signal is sent out from the right terminal of the fixing seat and the lower terminal of the glass aviation plug (7). The excitation signal is a direct current, and the change in the wall thickness of the oil well pipe and the change in the corrosion rate are calculated by the change in the excitation signal.

5. The high temperature and high pressure wellbore pipe string corrosion monitoring system according to claim 4, characterized in that: The excitation signal is a direct current, and the alternating current excitation signal is obtained by debugging a direct current signal, applied to both ends of the serial test piece through a signal transformer, and the direct current controls the current on and off through a field effect tube switch.

6. A monitoring method for a high-temperature and high-pressure wellbore pipe corrosion monitoring system as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Lower the system into the well to set the monitoring area and securely assemble it by snap-fitting; Step 2: Apply an excitation signal with a continuous frequency change to the monitoring area based on the current limiting resistor, and use the control switch to realize the synchronous application of the excitation signal, and use the analog switch to select the measurement channel, based on the common primary and secondary signal amplification circuits and analog-to-digital conversion circuits; the analog-to-digital conversion circuit uses a high-precision, wide dynamic range insulated gate bipolar transistor measurement chip, and can still save data after power failure, and can be used in an environment with a temperature of -55 to 210°C; Step 3: As the corrosion time progresses, the thickness of the test piece continues to decrease, and the test piece resistance also continues to decrease. The thinning amount and the test piece resistance show a linear relationship. The corrosion rate calculated based on the change in pipe wall thickness measured by the probe represents the corrosion rate of the target pipe string. The probe resistance of the test piece is calculated as shown in formula (1): In formula (1), Ω is the probe resistance of the test piece, ρ is the resistivity of the probe material of the test piece, Ω·m; L is the probe length of the test piece, mm; S is the cross-sectional area of ​​the probe of the test piece, mm 2 ; R and r are the outer diameter and inner diameter of the probe of the test piece, mm; The calculation of corrosion depth is shown in formula (2): In formula (2): r0 is the original radius of the test specimen, R0 is the resistance value before corrosion; R i is the resistance value after corrosion; In formula (3), T2 and T1 are the time difference between the two measurements; H2 and H1 are the difference between the two corrosion depth measurements; Step 4: After completing a maintenance cycle, the oil pipe is returned to the surface, the pipe clamp (18) is opened, and the pipe is brought back to the work area to extract data and analyze the collected data.

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