Wellhead lift safety monitoring device, system, and method

Abstract

The present disclosure provides a wellhead lifting safety monitoring device, system and method, the device comprising a control unit configured to acquire a secondary decay magnetic field signal generated by a casing from a pulsed magnetic field emitted by a pulsed eddy current detection assembly to a casing collar region; acquire a leakage magnetic field signal caused by the stress state of the riser flange connection region when the magnetic stress detection assembly locally magnetizes the riser flange connection region; extract displacement characteristic parameters from the secondary decay magnetic field signal, and generate relative displacement evolution data of the casing collar region relative to the pulsed eddy current detection assembly based on the displacement characteristic parameters; extract stress characteristic parameters from the leakage magnetic field signal, and generate composite stress evolution data representing the mechanical state of the riser flange connection region based on the stress characteristic parameters; determine the wellhead lifting driving type of the target wellhead based on the combination relationship between the relative displacement evolution data and the composite stress evolution data. The wellhead lifting problem can be identified and located in advance.

Description

Technical Field

[0001] This disclosure relates to the field of oil and gas well monitoring technology, and in particular to wellhead lift safety monitoring devices, systems and methods. Background Technology

[0002] During heavy oil thermal recovery, the continuous injection of high-temperature, high-pressure steam can trigger formation thermal expansion, leading to wellhead lift. Wellhead lift can cause consequences such as flange bolt overload, seal failure, and even casing damage, posing a serious threat to safe oil and gas production.

[0003] Currently, there are three main technical approaches for monitoring wellhead uplift: the first is direct displacement measurement technology, which acquires macroscopic displacement data of the wellhead relative to a fixed reference by setting displacement sensing devices at and around the wellhead; the second is indirect prediction technology based on mechanical models, which calculates the trend and magnitude of wellhead uplift by constructing a thermo-mechanical coupling theoretical model and combining it with downhole operating parameters; and the third is contact stress-strain monitoring technology, which monitors the stress state of the structure by arranging strain sensing elements in key parts of the wellhead structure to indirectly reflect the uplift situation.

[0004] However, these technologies can only obtain the final displacement results at the wellhead and cannot distinguish the mechanical causes of the lift. Moreover, downhole parameters are often difficult to obtain in real time and accurately, resulting in insufficient prediction accuracy and poor real-time performance. In addition, in the downhole environment, sensing elements are susceptible to harsh conditions such as high temperature, oil pollution, and strong electromagnetic interference, resulting in low long-term stability and reliability, which makes it difficult to meet the needs of long-term engineering monitoring. Therefore, there is an urgent need for a wellhead lift monitoring technology that can operate stably for a long time under harsh conditions such as high temperature, oil pollution, and strong electromagnetic interference in heavy oil thermal recovery, so as to provide reliable technical support for the safe production of oil and gas wells. Summary of the Invention

[0005] This disclosure provides a wellhead lift safety monitoring device, system, and method; it can distinguish the driving type of wellhead lift based on the joint analysis of pulse eddy current detection and magnetic stress detection, and achieve advanced identification and precise positioning of wellhead lift problems.

[0006] The technical solution disclosed herein is implemented as follows: In a first aspect, this disclosure provides a wellhead lift safety monitoring device, including a control unit configured to: acquire a secondary attenuated magnetic field signal generated by the casing when a pulsed magnetic field is emitted to the casing coupling area by a pulsed eddy current detection component; acquire a leakage magnetic field signal caused by the stress state of the riser flange connection area when the riser flange connection area is locally magnetized by a magnetic stress detection component; extract displacement characteristic parameters from the secondary attenuated magnetic field signal and generate relative displacement evolution data of the casing coupling area relative to the pulsed eddy current detection component based on the displacement characteristic parameters; extract stress characteristic parameters from the leakage magnetic field signal and generate composite stress evolution data characterizing the mechanical state of the riser flange connection area based on the stress characteristic parameters; and determine the wellhead lift drive type of the target wellhead based on the combination relationship between the relative displacement evolution data and the composite stress evolution data.

[0007] Secondly, this disclosure provides a wellhead lift safety monitoring system, including a pulsed eddy current detection component, a magnetic stress detection component, and a control unit. The pulsed eddy current detection component is fixed relative to the riser of the target wellhead and arranged corresponding to the casing coupling area of ​​the target wellhead. The pulsed eddy current detection component is used to emit a pulsed magnetic field to the casing coupling area and collect the secondary attenuated magnetic field signal generated by the casing. The magnetic stress detection component is arranged corresponding to the riser flange connection area of ​​the target wellhead. The magnetic stress detection component is used to locally magnetize the riser flange connection area and collect the leakage magnetic field signal caused by the stress state of the riser flange connection area. The control unit is communicatively coupled to both the pulsed eddy current detection component and the magnetic stress detection component. The control unit is configured to: extract displacement characteristic parameters from the secondary attenuated magnetic field signal, and generate relative displacement evolution data of the casing coupling region relative to the pulsed eddy current detection component based on the displacement characteristic parameters; extract stress characteristic parameters from the leakage magnetic field signal, and generate composite stress evolution data characterizing the mechanical state of the riser flange connection region based on the stress characteristic parameters; and determine the wellhead lift drive type of the target wellhead based on the combination relationship between the relative displacement evolution data and the composite stress evolution data.

[0008] Thirdly, this disclosure provides a wellhead lift safety monitoring method, comprising: acquiring a secondary attenuated magnetic field signal generated by the casing when a pulsed magnetic field is emitted to the casing coupling area by a pulsed eddy current detection component; acquiring a leakage magnetic field signal caused by the stress state of the riser flange connection area when the riser flange connection area is locally magnetized by a magnetic stress detection component; extracting displacement characteristic parameters from the secondary attenuated magnetic field signal, and generating relative displacement evolution data of the casing coupling area relative to the pulsed eddy current detection component based on the displacement characteristic parameters; extracting stress characteristic parameters from the leakage magnetic field signal, and generating composite stress evolution data characterizing the mechanical state of the riser flange connection area based on the stress characteristic parameters; and determining the wellhead lift drive type of the target wellhead based on the combination relationship between the relative displacement evolution data and the composite stress evolution data.

[0009] Fourthly, this disclosure provides a non-volatile computer-readable storage medium storing a computer program / instructions that, when executed by a processor, implement the steps of the wellhead lift safety monitoring method of the third aspect.

[0010] This disclosure provides a wellhead lift safety monitoring device, system, and method. By simultaneously acquiring the secondary attenuated magnetic field signal from the pulsed eddy current detection component and the leakage magnetic field signal from the magnetic stress detection component through a control unit, synchronous monitoring of the casing displacement state and the riser flange stress state related to wellhead lift is achieved. By extracting displacement characteristic parameters from the secondary attenuated magnetic field signal and generating relative displacement evolution data of the casing coupling area, the positional change process of the casing coupling relative to the pulsed eddy current detection component can be quantitatively and continuously reflected, providing a quantitative basis for determining whether actual casing lift has occurred. By extracting stress characteristic parameters from the leakage magnetic field signal and generating composite stress evolution data characterizing the mechanical state of the riser flange connection area, the mechanical state change process of the riser flange connection area can be quantitatively and continuously reflected, providing a quantitative basis for determining whether the wellhead structure is subjected to abnormal loads. Furthermore, by determining the wellhead lift driving type of the target wellhead based on the combination relationship between the relative displacement evolution data and the composite stress evolution data, different wellhead lift mechanical roots can be accurately distinguished, providing a scientific basis for subsequently developing targeted wellhead safety control measures. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the system architecture of a wellhead lift safety monitoring system provided in an embodiment of this disclosure.

[0012] Figure 2 This is a schematic diagram of the circuit structure of a pulsed eddy current detection component provided in an embodiment of the present disclosure.

[0013] Figure 3This is a schematic diagram of the probe structure of the pulsed eddy current detection assembly provided in an embodiment of this disclosure.

[0014] Figure 4 This is a schematic diagram of the circuit structure of a magnetic stress detection component provided in an embodiment of this disclosure.

[0015] Figure 5 This is a schematic diagram of the probe structure of the magnetic stress detection assembly provided in an embodiment of this disclosure.

[0016] Figure 6 This is a waveform diagram of a bipolar step transmission signal provided in an embodiment of this disclosure.

[0017] Figure 7 A flowchart of a wellhead lift safety monitoring method provided in an embodiment of this disclosure.

[0018] Figure 8 This is a schematic diagram of the composition of the wellhead lift safety monitoring device provided in the embodiments of this disclosure.

[0019] Figure 9 This is a schematic diagram of the composition of a computer device provided in an embodiment of this disclosure. Detailed Implementation

[0020] The technical solutions of this disclosure will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art should fall within the protection scope of this disclosure.

[0021] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The singular forms “a,” “the,” and “the” used in this disclosure are also intended to include the plural forms unless the context clearly indicates otherwise.

[0022] Furthermore, in the embodiments of this disclosure, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0023] To facilitate understanding of the technical solutions of the embodiments of this disclosure, the related technologies of the embodiments of this disclosure are described below. The following related technologies are optional solutions and can be combined with the technical solutions of the embodiments of this disclosure in any way, and they all fall within the protection scope of the embodiments of this disclosure.

[0024] During the thermal recovery of heavy oil, the continuous injection of high-temperature and high-pressure steam causes thermal expansion of the formation and casing. The wellhead uplift caused by thermal expansion not only changes the stress boundary conditions at the bottom of the riser, but may also lead to overload of flange connection bolts, seal failure, and even casing damage, posing a significant threat to the safe production of oil and gas wells.

[0025] The mechanical mechanism of wellhead lift is complex. Its root cause may be the actual axial displacement of the deep casing under thermal stress (hereinafter referred to as casing-driven lift), or the relative lift caused by the riser itself due to stress or deformation (hereinafter referred to as riser-force-driven lift). There are also cases where the casing has displaced, but the lift force is partially released or buffered during transmission (hereinafter referred to as lift force-release-type lift). The risk levels and handling measures for these three situations are drastically different. Without distinguishing the driving type, it is impossible to provide a basis for developing targeted prevention and control measures on-site.

[0026] However, existing monitoring technologies struggle to effectively differentiate between the aforementioned drive types. Direct displacement measurement is a reactive method, unable to issue early warnings before macroscopic displacement occurs at the wellhead; indirect calculation and prediction methods require downhole thermo-mechanical coupling parameters that are difficult to obtain in real time, resulting in insufficient prediction accuracy and timeliness; strain measurement methods utilize resistance strain gauges, which exhibit poor long-term stability in high-temperature, oil-contaminated, and strongly electromagnetically interfered field environments, hindering their engineering applications. More importantly, relying solely on measuring relative displacement at the wellhead cannot trace the mechanical root cause of the lift, determine whether it is driven by deep casing or by the riser itself, or ascertain whether the lift force has been released. This leads to a situation where on-site response is only reactive after a wellhead uplift accident occurs, making it highly susceptible to serious production accidents such as flange seal failure, casing rupture, and oil and gas leaks due to delayed response. Furthermore, because the mechanical causes and true risk levels of the uplift cannot be accurately determined, on-site responses often rely on conservative, generalized, "one-size-fits-all" control measures. This not only significantly increases unnecessary maintenance costs and production losses but may also leave significant safety hazards due to mismatches between control measures and actual risks. In addition, the lack of effective monitoring of the uplift force transmission process can lead to systematic misjudgments of the wellhead structure's stress state. For example, a low-risk situation where the uplift force has been fully released might be judged as high-risk, resulting in blind production shutdowns, or the high-risk situation of riser overload might be ignored, leading to structural fatigue failure. This severely restricts the safe production efficiency and life-cycle integrity management level of oil and gas wells.

[0027] In view of this, this disclosure provides a wellhead lift safety monitoring device, system and method, which jointly acquires the secondary attenuated magnetic field signal of the casing coupling area and the leakage magnetic field signal of the riser flange connection area, respectively generates relative displacement evolution data and composite stress evolution data, and determines the driving type of wellhead lift based on the combination relationship between the two, thereby achieving accurate analysis of the root cause of wellhead lift and advanced identification of risks.

[0028] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the system architecture of a wellhead lift safety monitoring system provided in an embodiment of this disclosure. In some embodiments of this disclosure, the wellhead lift safety monitoring system is applied to an offshore oil and gas extraction environment. This environment, from top to bottom, includes an operating platform 15, a sea surface 16, and a deep-sea wellbore structure located below the sea surface. A riser 11 extends downward from the operating platform 15 and passes through the sea surface 16 into the seawater environment; inside the riser 11, multiple layers of casings of different sizes (such as 13-inch 3-casing 121 and 9-inch 5-casing 122) are nested, and these casings also extend downward below the sea surface. A ground deployment area for the wellhead lift monitoring system is formed in the open space between the operating platform and the sea surface. The wellhead lift safety monitoring system mainly includes a wellhead lift safety monitoring device (specifically implemented as a host computer 30 and its internal control unit), a pulse eddy current detection component 10, and a magnetic stress detection component 20.

[0029] like Figure 1 As shown, the pulsed eddy current detection component 10 is typically provided with two sets (e.g., Figure 1 The displacement monitoring devices 18 and 19 are installed on the outer wall of the riser 11, below the work platform 15 and above the sea surface 16, to monitor different sizes of sleeves (such as 13-inch 3-sleeve 121 and 9-inch 5-sleeve 122). Each pulse eddy current detection assembly 10 includes: The probe is fixed to the outer wall of the riser pipe 11 below the working platform 15, and its height corresponds to the center position of the inner sleeve coupling 13 of the riser pipe. The probe integrates a transmitting coil and a receiving coil.

[0030] Circuit system: including a transmitting circuit connected to the transmitting coil, a receiving circuit connected in sequence to the receiving coil, a signal processing circuit, and a data acquisition circuit.

[0031] Processing and Communication Unit: Includes CPU, data integration and communication module, and communication module. The CPU is responsible for controlling the transmitting circuit to generate bipolar pulse signals, performing preliminary processing on the acquired secondary field attenuation signals, summarizing the data to the data integration and communication module via the CAN bus, and finally uploading it to the host computer 30 via the communication module.

[0032] A magnetic stress detection component 20 is deployed at the riser flange 14 to sense the stress state of the flange end face. Its hardware components include: Magnetic stress detection probe 17: fixed to the flange end face of the riser pipe.

[0033] Circuit system: including transmitting circuit (receiving PWM signal output from CPU for driving), signal conditioning circuit, and data acquisition circuit.

[0034] Processing and storage unit: includes CPU, data integration and storage circuit, and communication module. The CPU controls the drive transmission circuit to achieve local magnetization and collects the leakage magnetic field signal after it has been processed by the signal conditioning circuit. The data is transmitted to the data integration and storage circuit for local backup via CAN bus and simultaneously uploaded to the host computer 30 via the communication module.

[0035] In some examples, the pulsed eddy current detection component 10 is fixed relative to the riser 11 at the target wellhead and arranged corresponding to the casing coupling area of ​​the target wellhead. Specifically, the probe is fixed to the riser wall, and its height is determined by the exact center position of the casing coupling; the same deployment method is used for casings of different inlets (sizes). This component is used to emit a pulsed magnetic field into the casing coupling area and to acquire the secondary attenuated magnetic field signal generated by the casing to calculate the casing displacement in real time.

[0036] The magnetic stress detection component 20 is arranged corresponding to the riser flange connection area of ​​the target wellhead. Specifically, the stress measurement probe is fixed to the end face of the riser flange, and the fixing height is determined by the flange end face. This component is used to locally magnetize the riser flange connection area and simultaneously acquire the magnetic signal of the riser flange end face, thereby retrieving the stress state.

[0037] The host computer 30 is equipped with a control unit, which is communicatively coupled to the pulse eddy current detection component 10 and the magnetic stress detection component 20, respectively. The control unit is configured to execute the following time-sharing or synchronous processing logic: The system acquires the secondary attenuated magnetic field signal generated by the casing 13 when the pulsed eddy current detection component 10 emits a pulsed magnetic field to the casing coupling area; it acquires the leakage magnetic field signal caused by the stress state of the riser flange connection area when the magnetic stress detection component 20 locally magnetizes the riser flange connection area; it extracts displacement characteristic parameters from the secondary attenuated magnetic field signal and generates relative displacement evolution data of the casing coupling area relative to the pulsed eddy current detection component 10 based on the displacement characteristic parameters; it extracts stress characteristic parameters from the leakage magnetic field signal and generates composite stress evolution data characterizing the mechanical state of the riser flange connection area based on the stress characteristic parameters; and it determines the wellhead lift drive type of the target wellhead based on the combination relationship between the relative displacement evolution data and the composite stress evolution data.

[0038] The casing coupling area refers to the space surrounding the junction of the casing body and the coupling boss along the axial direction of the casing. The coupling boss has a larger metal wall thickness than the casing body, and its position changes when the casing undergoes axial displacement. Therefore, the casing coupling area is a sensitive area for detecting axial displacement of the casing. The riser flange connection area refers to the area near the connection between the bottom flange of the riser and the surrounding bolts. This area bears axial tensile, compressive, or bending stresses when the wellhead experiences uplift, making it a critical area for stress concentration.

[0039] In some examples, the generation mechanism of the secondary decaying magnetic field signal is as follows: the transmitting coil of the pulsed eddy current detection component applies a pulsed magnetic field to the bushing. This transient magnetic field induces decaying eddy currents in the bushing's metal wall, which in turn generate a secondary decaying magnetic field with the same direction as the initial magnetic field. The receiving coil picks up this secondary decaying magnetic field and converts it into a voltage signal. Since the strength and decay rate of the secondary decaying magnetic field are affected by the mass of the bushing metal (including wall thickness, conductivity, etc.), the thicker the metal wall and the better the conductivity, the stronger the induced magnetic field signal and the slower the decay. Therefore, by analyzing the characteristic parameters of the secondary decaying magnetic field signal, the relative position change of the bushing can be inverted. This measurement principle is non-contact, eliminating the need to install any sensors on the high-temperature, high-pressure bushing surface, thus fundamentally solving the problem of poor stability of strain measurement methods in harsh environments.

[0040] In some examples, the generation mechanism of the leakage magnetic field signal is as follows: the magnetic stress detection component locally magnetizes the pipe wall, forming a closed magnetic loop between the flange and adjacent pipe walls; when the flange end face is subjected to abnormal tensile, compressive, or bending stress, the magnetic domain structure inside the material undergoes a directional change (i.e., the inverse magnetostrictive effect, also known as the Villari effect). The magnetic lines of force originally confined inside the pipe wall are distorted and leak into space in stress concentration areas (such as the flange neck or around bolt holes), forming a leakage magnetic field. The magnetic induction unit arranged around the flange picks up the leakage magnetic field signal, thus retrieving the actual stress distribution and trend of the flange end face. Similarly, this measurement method is non-contact and suitable for field environments with high temperature, oil contamination, and strong electromagnetic interference.

[0041] In some examples, relative displacement evolution data refers to the time-series recording of the displacement change of the sleeve coupling region relative to the pulsed eddy current detection component. Since the pulsed eddy current detection component is fixed to the riser wall and its position relative to the riser remains constant, this relative displacement essentially reflects the axial displacement of the sleeve coupling relative to the riser, i.e., whether the deep sleeve has undergone actual axial displacement. Composite stress evolution data refers to the time-series recording of the changes in composite stress values ​​in the riser flange connection region, reflecting the stress state and its changing trend on the riser flange end face.

[0042] In some embodiments, the control unit may be implemented by a central processing unit (CPU), a microcontroller, a field-programmable gate array (FPGA), or a combination thereof. The CPU within each detection component communicates reliably with the host computer via a CAN bus and a communication module, enabling local data transmission and backup.

[0043] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the circuit structure of a pulsed eddy current detection component provided in an embodiment of this disclosure. The pulsed eddy current detection component 10 is used to accurately excite and sense the secondary attenuated magnetic field signal of the bushing. Figure 2 As shown, the pulsed eddy current detection assembly 10 adopts a modular design, mainly consisting of a transmitting module, a receiving module, and a data integration and communication module. The pulsed eddy current detection assembly 10 includes a probe section, which integrates a magnetic core, a transmitting coil 101, and a receiving coil 102.

[0044] The transmitting module is used to generate the excitation current required to generate a primary pulse magnetic field. The CPU 107 inside the pulse eddy current detection component 10 serves as the core control unit and is responsible for the control logic to generate a bipolar step signal. Driven by the CPU 107, the transmitting circuit 103 injects a bipolar step current into the transmitting coil 101, thereby generating a primary pulse magnetic field in the space around the wellhead casing.

[0045] The receiving module is used to capture weak magnetic signals reflecting the characteristics of the bushing. The receiving coil 102 picks up the secondary attenuated magnetic field signal generated by the bushing and converts it into a voltage signal. The voltage signal first enters the receiving circuit 104, and then undergoes filtering and amplification processing by the signal conditioning circuit 105. This stage significantly improves the signal-to-noise ratio by suppressing noise interference. The processed analog signal enters the data acquisition circuit 106 for analog-to-digital conversion, and after being converted into a digital signal, it is fed back to the CPU 107.

[0046] The pulsed eddy current detection component 10 supports multi-probe collaborative operation. After preprocessing the acquired raw feature signals, the CPU 107 aggregates the feature data to the data integration circuit 108 via a bus. Finally, the communication module 109 uploads the integrated monitoring data to the host computer 30 in real time. The host computer 30 accurately calculates the sleeve displacement and structural anomalies based on the received signal amplitude A and attenuation time constant τ.

[0047] Please refer to Figure 3 , Figure 3This is a schematic diagram of the probe structure of the pulsed eddy current detection assembly provided in this embodiment. The probe portion of the pulsed eddy current detection assembly 10 adopts a compact structure design with layered winding, which can achieve efficient coupling of magnetic field energy and pure signal acquisition.

[0048] In some examples, a magnetic core 100 is disposed at the center of the probe. This magnetic core 100 is made of a soft magnetic alloy with high permeability, and its relative permeability ranges from u. r 1×10 4 Up to 1×10 5 On the outside of the magnetic core 100, a coil assembly is integrated using a precision winding process. Inner layer: The transmitting coil 101 is wound tightly in close contact with the magnetic core 100.

[0049] Outer layer: The receiving coil 102 is coaxially wound around the outer periphery of the transmitting coil 101.

[0050] Specifications: Both the transmitting and receiving coils use 0.13mm diameter enameled wire, with a total of 8 layers and 460 turns.

[0051] Thermal insulation: Polyimide glass fiber is used as thermal insulation material between each layer of the coil to ensure that the sensor can work stably for a long time in the high-temperature environment of heavy oil thermal recovery.

[0052] like Figure 3 As shown, the probe is fixed to the outer wall of the water-tight pipe 11. In the working state, there is an air gap between the probe and the inner sleeve (including the outer tube 121 and the inner tube 122).

[0053] This structural design, which layers the transmitting and receiving coils and winds them on the same magnetic core, offers advantages such as efficient coupling, crosstalk suppression, and compact fit. By utilizing a shared high-permeability magnetic core, the excitation magnetic field is more concentrated on the casing, generating stronger induced eddy currents, while maximizing the receiving coil's pickup efficiency for secondary attenuated magnetic fields. The layered spatial isolation of the coils effectively suppresses direct electromagnetic crosstalk between the excitation magnetic field and the received signal, allowing the characteristic signal acquired by the receiving coil to more purely reflect casing displacement and metal state. The compact physical volume is well-suited for engineering deployments in confined wellhead spaces, providing a reliable hardware foundation for accurate casing displacement monitoring.

[0054] The pulsed eddy current detection component consists of a transmitting module and a receiving module at the circuit level. In the transmitting module, the CPU, as the core control unit, is responsible for the control logic that generates a bipolar step signal. Driven by the CPU, the transmitting circuit injects a bipolar step current into the transmitting coil, thereby exciting a primary pulsed magnetic field in the space around the wellhead casing. This transient magnetic field induces decaying eddy currents in the casing's metal wall, generating a secondary decaying magnetic field in the same direction as the initial magnetic field. In the receiving module, the receiving circuit picks up the secondary decaying magnetic field signal containing casing information through the receiving coil and converts it into a voltage signal. The signal conditioning circuit filters and amplifies this voltage signal to suppress noise and improve the signal-to-noise ratio. The processed analog signal enters the data acquisition circuit for analog-to-digital conversion, converting it into a digital signal before transmitting it to the data integration and communication module.

[0055] Using a bipolar step current (instead of a unipolar pulse) to drive the transmitting coil can effectively eliminate the influence of DC bias on the received signal, improve the symmetry and stability of the signal, and reduce the requirements for the dynamic range of the subsequent amplifier circuit.

[0056] Please refer to Figure 4 , Figure 4 This is a schematic diagram of the circuit structure of a magnetic stress detection component provided in an embodiment of this disclosure. The magnetic stress detection component 20 realizes real-time detection of stress state through an electromagnetic coupling mechanism.

[0057] The CPU 207 inside the magnetic stress detection component 20 serves as the logic control core, outputting a PWM (pulse width modulation) control signal to the transmitting circuit 204. The transmitting circuit 204 drives the excitation coil 201 wound on the U-shaped magnetic core to generate an alternating current, thereby establishing a controllable magnetic circuit inside the tested water-proof pipe flange 14 and achieving local magnetization.

[0058] The magnetic induction unit 202 (which can be implemented as a high-sensitivity TMR magnetoresistive chip) is responsible for detecting the spatial leakage magnetic field signal generated by stress concentration in the flange and converting it into a voltage signal. This voltage signal is sent to the signal conditioning circuit 205. The signal conditioning circuit 205 includes two modules: low-pass filtering and amplification, used to filter out high-frequency electromagnetic noise in the environment and amplify the weak stress response signal. The amplified signal is then subjected to high-precision analog-to-digital conversion by the signal acquisition circuit 206 and subsequently transmitted to the CPU 207 for feature extraction.

[0059] Based on magnetic stress measurement theory (including static signal, dynamic rate of change, and temperature compensation logic), CPU207 calculates the composite stress value of the flange end face. The calculation results are transmitted to the data integration and storage circuit 208 via the CAN bus for local storage of historical monitoring data. Finally, the data is uploaded to the host computer 30 in real time via the communication module 209. The host computer 30 combines the displacement data for joint analysis to achieve early-stage risk identification and precise location.

[0060] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the probe structure of the magnetic stress detection assembly provided in an embodiment of this disclosure.

[0061] In some examples, the magnetic field detection probe employs an integrated structural design, specifically including: U-shaped magnetic core 200: Made of a soft magnetic alloy with high permeability (relative permeability u) r The range is 1×10 4 Up to 1×10 5 It serves as a magnetic circuit guide. Its geometry has been optimized: external height is 60mm and length is 30mm; internal height is 42mm and length is 28mm.

[0062] Excitation coil 201: It uses 0.05mm diameter enameled wire, and is wound in 4 layers on the U-shaped magnetic core 200, for a total of 500 turns.

[0063] Magnetic induction unit 202: Located at the center of the opening of the U-shaped magnetic core, it uses a high-sensitivity TMR magnetoresistive chip to capture extremely weak changes in the leakage magnetic field vector.

[0064] Magnetic shield 203: Located on the outside of the magnetic induction unit 202, with dimensions of 14mm in length, 10mm in height, and 1mm in thickness, it is used to suppress environmental magnetic noise and stabilize the local magnetic field distribution, thereby improving the signal-to-noise ratio.

[0065] like Figure 5 As shown, the probe is fixed to the end face of the riser flange 13. Its working mechanism is based on the inverse magnetostriction effect (i.e., Villari effect) of ferromagnetic materials: when the wellhead is raised, causing stress concentration on the end face of flange 13, the magnetic domains inside the material change orientation, causing the magnetic lines of force that were originally closed in the pipe wall to be distorted and leak into the air.

[0066] The closed magnetic circuit established by the U-shaped magnetic core 200 can effectively concentrate magnetic field energy, enabling the magnetic induction unit 202 to accurately pick up the leakage magnetic field strength H caused by stress. p .

[0067] This non-contact measurement probe can not only reflect the actual stress distribution and changing trend of the flange end face, but also greatly improves the survival rate and measurement accuracy in harsh environments such as heavy oil thermal recovery due to its built-in magnetic shielding structure and high temperature resistant design.

[0068] The magnetic induction unit employs a high-sensitivity tunnel magnetoresistive (TMR) chip. This chip can convert weak leakage magnetic field changes into a voltage signal that is functionally related to stress. It features high sensitivity and low noise, making it suitable for detecting weak leakage magnetic fields generated in stress concentration areas. In some examples, the TMR magnetoresistive chip is positioned between the two ends of the U-shaped magnetic core, close to the surface of the flange under test, to maximize the pickup efficiency of leakage magnetic fields in stress concentration areas.

[0069] The magnetic stress detection component's circuitry mainly comprises two modules: low-pass filtering and amplification. These modules filter out high-frequency noise signals while amplifying weak stress response signals. The signal acquisition circuit performs high-precision analog-to-digital conversion on the magnetic stress measurement signal, then transmits the acquired raw digital signal to the CPU. Based on magnetic stress measurement theory, the CPU performs digital filtering, feature extraction, and inversion calculations on the signal, ultimately obtaining stress change data for the corresponding region. After processing by the CPU, the stress data is transmitted to the data integration and storage circuit via the controller area network (CAN bus). The data integration and storage circuit stores historical stress change information and uploads the processed data to the host computer via the CAN bus. The host computer displays the stress values ​​and change curves of each monitoring point in real time.

[0070] In some examples, the magnetic stress detection assembly can arrange multiple probes circumferentially on the flange end face of the riser (e.g., 4 or 8 probes evenly distributed along the circumference) to obtain information on the circumferential stress distribution on the flange end face. By comparing the stress values ​​at different circumferential positions, it can be determined whether the lifting is uniform. If the stress changes at each position are basically the same, it is a uniform lifting; if the differences at each position are significant, there may be eccentric force or loose bolts, thus further enriching the basis for determining the drive type.

[0071] In practical applications, if only displacement data is available without stress data, it is impossible to determine whether the displacement has been transmitted to the riser and caused overload; similarly, if only stress data is available without displacement data, it is impossible to determine whether the increase in stress stems from the actual upward movement of the deep casing or from the stress deformation of the riser itself. Only by combining both can the root cause of the risk be accurately located. By jointly analyzing quantitative information on "whether there is actual displacement" (relative displacement evolution data) and quantitative information on "whether there is stress and the degree of stress" (composite stress evolution data), a combined relationship can be formed. This overcomes the difficulty of tracing the source of wellhead lift problems. Before displacement occurs, stress risks can be detected in advance through changes in magnetic signals, and the type of lift drive can be accurately distinguished, enabling early identification of wellhead lift. This provides reliable technical support for the safe production of heavy oil thermal recovery wells and other high-temperature, high-pressure oil and gas wells.

[0072] Please refer to Figure 6 , Figure 6 This is a waveform diagram of a bipolar step transmission signal provided in an embodiment of this disclosure. The waveform is generated by the CPU 107 in the pulse eddy current detection component 10 and injected into the transmission coil 101 through the transmission circuit 103.

[0073] like Figure 6 As shown, this embodiment uses a bipolar step current as the excitation signal. The signal consists of alternating combinations of positive and negative pulses. Compared to a unipolar signal, the bipolar step current can effectively suppress the magnetization accumulation effect of the magnetic core 100, reduce signal zero-point drift, and thus improve measurement stability in the high-temperature environment at the wellhead. When current is injected into the transmitting coil 101, a pulsed magnetic field is generated in the space around the casing; at the moment of excitation cutoff, the current rapidly drops to zero, the transient magnetic field disappears, and decaying eddy currents are induced in the metal wall of the casing.

[0074] The receiving coil 102 picks up the secondary decaying magnetic field signal generated by the aforementioned decaying eddy current. To quantitatively calculate the bushing displacement from the complex induced signal, this embodiment is based on... Figure 6 The temporal relationship shown extracts two key feature parameters: amplitude A and decay time constant τ.

[0075] In some embodiments of this disclosure, the displacement characteristic parameters include amplitude A and decay time constant τ.

[0076] The amplitude A is defined as the voltage value corresponding to a fixed delay after the excitation of the pulsed magnetic field is turned off. Specifically, the transmitting coil injects a bipolar step current into the bushing under the drive of the control unit. This current stops at the instant the excitation is turned off, and the secondary attenuated magnetic field signal picked up by the receiving coil immediately begins to attenuate. After a fixed delay time t0 after the excitation is turned off, the voltage value of the received signal is sampled, and the obtained voltage value is the amplitude A.

[0077] The purpose of setting a fixed delay is that, in the very short time after the excitation is turned off, the direct electromagnetic crosstalk from the excitation coil to the receiving coil has not completely dissipated. Sampling during this period would introduce a large error. The fixed delay ensures that the sampling time falls within the time window when the crosstalk has dissipated but the secondary field of the bushing has not completely decayed, thus obtaining a pure signal reflecting the metal state of the bushing. The amplitude A mainly reflects the lift-off distance between the probe and the bushing and the local wall thickness. When the bushing is lifted so that the coupling boss (with a wall thickness greater than the bushing body) enters the probe detection area, the local metal mass increases, the excited eddy currents become stronger, and the amplitude of the secondary field increases accordingly. Therefore, the increase in amplitude A is a direct representation of the bushing coupling displacement.

[0078] The decay time constant τ is defined as the time constant obtained by fitting the late signal segment of the secondary decaying magnetic field signal with an exponential decay. In the late stage after excitation turn-off (far from the crosstalk influence zone), the secondary decaying magnetic field signal approximately follows an exponential decay law. The exponential decay time constant τ is obtained by fitting this signal segment exponentially. The decay time constant τ mainly reflects the change in casing wall thickness: the thicker the casing wall, the greater the penetration depth of the induced eddy current, the slower the eddy current decay, and the larger the corresponding τ. When the coupling boss enters the probe detection area, the local wall thickness increases significantly, and τ increases synchronously.

[0079] The reason for extracting two characteristic parameters, amplitude A and decay time constant τ, instead of using only a single parameter is that amplitude A is more sensitive to the distance between the probe and the sleeve (i.e., the lift-off distance), while τ is more sensitive to changes in wall thickness. Using the two together improves the accuracy of displacement calculation through dual-parameter weighting and provides a data basis for distinguishing displacement signals from permeability fluctuation interference.

[0080] In some embodiments of this disclosure, relative displacement evolution data ΔL of the sleeve coupling region relative to the pulse eddy current detection component is generated by weighted linear combination based on the relative changes in amplitude A and decay time constant τ.

[0081] In some examples, the displacement ΔL is linearly related to the relative changes in amplitude A and decay time constant τ, as expressed by: ΔL =c1×(A - A0) / A0+ c2×(τ - τ0) / τ0 Wherein, A0 and τ0 are the reference amplitude and reference attenuation time constant when the probe is aligned with the sleeve body (non-coupling area) after installation, respectively, and c1 and c2 are the displacement weighting coefficients corresponding to the amplitude and the displacement weighting coefficients corresponding to the attenuation time constant, respectively, all of which are determined through calibration experiments.

[0082] The calculation uses relative changes ((A - A0) / A0 and (τ - τ0) / τ0) instead of absolute values ​​because different casing specifications and different installation spacings will cause differences in the absolute values ​​of A0 and τ0. Using relative changes can eliminate the influence of differences in installation conditions, so that the calculation results only reflect the changes in the relative positions of the casing couplings, thus improving the applicability under different well conditions.

[0083] In actual operation, the control unit extracts A and τ in real time, corrects for temperature, and then inputs them into the above formula to calculate ΔL. When ΔL continuously exceeds the preset displacement threshold and τ increases synchronously, it is determined to be an effective lifting displacement. The temperature correction is introduced to eliminate the influence of on-site temperature fluctuations on permeability, thereby avoiding signal drift caused by temperature changes from being misjudged as displacement.

[0084] In some examples, the relative displacement evolution data includes not only the calculated value of the displacement ΔL at the current moment, but also historical ΔL data recorded in time series form, so that the control unit can analyze the trend of displacement change (e.g., step rise, periodic rise, or slow monotonous increase) and provide a time-series basis for determining the drive type.

[0085] In some embodiments of this disclosure, the reference amplitude A0, the reference attenuation time constant τ0, the displacement weighting coefficients c1 and c2, and the displacement temperature compensation amount are all determined by calibration data, which are obtained through calibration experiments.

[0086] In some examples, the calibration experiment uses a casing sample section and coupling boss of the same specifications as the casing in the field. The probe of the pulse eddy current detection assembly is fixed on a precision translation stage. By controlling the translation stage, different relative displacements between the probe and the casing coupling are simulated. The amplitude A and attenuation time constant τ corresponding to each displacement are recorded. The displacement weighting coefficients c1 and c2 are solved by linear regression. The reference amplitude A0 and reference attenuation time constant τ0 are the acquired values ​​when the probe is aligned with the casing body (the coupling boss is not within the probe's detection range).

[0087] To obtain the temperature compensation coefficient, calibration experiments were repeated under different temperature conditions. Specifically, while maintaining the same relative displacement, the casing sample was heated to different temperatures, and the temperature change and the corresponding A and τ drifts were recorded. The temperature compensation coefficient was then fitted to obtain the coefficient. During actual system operation, the control unit reads the real-time temperature data from the temperature sensor, multiplies the temperature change by the corresponding temperature compensation coefficient, and corrects the original calculated value, thus eliminating the influence of temperature fluctuations on the displacement calculation results.

[0088] In some examples, calibration experiments can be performed separately for different casing sizes (e.g., 9-inch 5-inch casing and 13-inch 3-inch casing), establishing independent calibration parameter sets for different casing sizes to improve the accuracy of displacement calculation under different well conditions. In some examples, calibration data is stored in the local memory of the control unit and is automatically loaded after the system is powered on, eliminating the need for recalibration each time the system starts.

[0089] In actual monitoring, changes in the secondary attenuated magnetic field signal are not solely caused by the displacement of the bushing coupling. Fluctuations in the bushing's magnetic permeability (e.g., due to temperature changes, material aging, or corrosion) can also alter the signal characteristics, potentially leading to misjudgment if not differentiated. Therefore, some embodiments of this disclosure use the ratio of early attenuation rate to late attenuation rate to distinguish the causes of changes in the secondary attenuated magnetic field signal.

[0090] Specifically, the control unit determines the first attenuation rate of the secondary attenuated magnetic field signal in the early time window and the second attenuation rate in the late time window, and based on the ratio between the first attenuation rate and the second attenuation rate, distinguishes whether the change of the secondary attenuated magnetic field signal relative to the reference secondary attenuated magnetic field signal is caused by the displacement of the bushing coupling area or by the fluctuation of the bushing permeability.

[0091] The ability to differentiate the causes of changes in the secondary attenuation magnetic field signal based on the ratio of early to late attenuation rates is grounded in the following physical evidence: Pulsed eddy current signals contain rich spectral components. From a time-domain perspective, the early signal (the signal within a short time after excitation shutdown) primarily reflects the geometric relationship between the probe and the sleeve (i.e., the lift-off distance and the presence of the coupling boss), corresponding to high-frequency components; the late signal (the signal within a longer time after excitation shutdown) primarily reflects the permeability of the sleeve material, corresponding to low-frequency components. When sleeve coupling displacement occurs, the coupling boss enters the detection area, causing all frequency components to increase proportionally, meaning the early and late signals increase synchronously and proportionally, and the ratio of their attenuation rates remains essentially unchanged. However, when the sleeve permeability fluctuates, the change in permeability mainly affects the low-frequency components (i.e., the late signal), while the early signal is relatively less affected, leading to a change in the ratio of early to late attenuation rates.

[0092] In some examples, the control unit calculates the ratio of the signal amplitude in the early time window to the signal amplitude in the late time window and compares it with a reference ratio. If the deviation of this ratio from the reference value exceeds a preset threshold, it is determined that the current signal change is mainly caused by permeability fluctuations; if the ratio does not exceed the threshold and ΔL continuously increases, it is determined to be an effective coupling displacement.

[0093] By introducing this differentiation mechanism, the changes in magnetic permeability caused by sleeve corrosion, incomplete temperature compensation, or material aging can be effectively avoided from being misjudged as sleeve lifting displacement, thereby improving the reliability of the monitoring system.

[0094] In some examples, the differences in timing characteristics between displacement and corrosion signals can be used to aid in differentiation. The coupling displacement signal typically exhibits one or more narrow, "protrusion"-shaped signal jumps along the casing axis, with the amplitude A increasing synchronously with the decay time constant τ. Uniform wall thickness corrosion results in a slow, unidirectional signal change (A and τ gradually decrease as corrosion intensifies), without local spikes. Localized corrosion pits cause brief signal dips, rather than asymmetrical jumps. In some examples, the displacement signal is generally step-like or periodic (e.g., rising during a steam injection cycle and not receding), while corrosion is a slow, irreversible process; further differentiation can be achieved through trend analysis of the timing data.

[0095] In some embodiments of this disclosure, the stress characteristic parameters extracted from the leakage magnetic field signal include static leakage magnetic flux change, leakage magnetic flux change rate, and temperature change. The composite stress evolution data is generated based on the above three characteristic parameters through a weighted linear combination.

[0096] The physical basis of magnetic stress detection is the inverse magnetostriction effect (also known as the Villari effect): when a ferromagnetic material is subjected to an external force, its permeability or magnetization state changes. Specifically, the relationship between magnetic induction intensity B, magnetic field strength H, and permeability μ(σ) can be expressed as: B = μ(σ)×H Where μ(σ) is a function of stress σ. When stress concentration exists in the flange connection area of ​​the riser pipe, the magnetic field lines are no longer completely confined inside the pipe wall, but leak into the air, forming a leakage magnetic field. The leakage magnetic field strength H p The relationship with stress variation can be expressed as: H p = f(dμ / dx, σ, dσ / dx) Where x represents the spatial coordinates along the detection path on the surface of the riser flange. The stress value on the end face of the riser flange can be deduced from the detected leakage magnetic field signal.

[0097] The static leakage magnetic flux change refers to the difference (Vout - V0) between the voltage value Vout output by the magnetic induction unit in real time and the reference voltage value V0 when the wellhead is in normal working condition after installation. This difference reflects the change in the static leakage magnetic field caused by stress, that is, the degree of static force change of the flange end face relative to the reference state at the current moment.

[0098] The rate of change of leakage magnetic field refers to the leakage magnetic field strength H p First derivative with respect to time H p / t, or the rate of change of the magnetic field over time, is used to capture the intensity of stress fluctuations. In the early stages of wellhead uplift, the stress on the flange end face may not yet have reached a high absolute value, but its rate of change has already accelerated significantly. By introducing the leakage magnetic flux change rate, the rapid trend of stress change can be detected in advance when the static leakage magnetic flux change is not yet significant, thereby achieving early warning.

[0099] The temperature change ΔT refers to the difference between the current temperature and the reference temperature, used to eliminate the influence of environmental thermal interference on the measured magnetic stress value. The magnetic permeability of ferromagnetic materials generally decreases with increasing temperature. In the high-temperature heavy oil thermal recovery environment, without temperature compensation, the change in magnetic permeability caused by temperature increase will be superimposed on the change in leakage magnetic field caused by stress, resulting in a systematic deviation in the stress inversion value.

[0100] Based on the above three characteristic parameters, the stress value σf in the composite stress evolution data is calculated by the following formula: σf = α×(Vout -V0) + β·( H p / t) + γ×ΔT Wherein: α is the static magnetic signal coefficient, reflecting the conversion sensitivity between static leakage magnetic field changes and stress, with dimensions in MPa, determined through laboratory tensile / compression calibration experiments: a known stress is applied to a specimen of the same material, the static voltage signal change is recorded, and the linear slope is fitted to obtain α; β is the dynamic stress coefficient, reflecting the proportional relationship between the leakage magnetic field change rate and the severity of stress fluctuations, typically ranging from 0.01 to 10, measured simultaneously in dynamic loading experiments (e.g., impact or alternating stress). H p / t and the rate of stress change are obtained through regression analysis; γ is the temperature compensation coefficient, which reflects the influence of temperature change on the measured value of magnetic stress. Its dimension is MPa / ℃, and its value range is usually from -1 to -0.01 MPa / ℃. It is obtained by heating the specimen to different temperatures under stress-free conditions, recording the magnetic signal drift, and fitting the data.

[0101] The composite stress inversion formula, which uses three superimposed terms instead of just the static leakage magnetic flux change, is employed because: the static term α×(Vout -V0) reflects the current absolute stress level, while the dynamic term β·( H p / t) is used to capture the rapid change trend of stress, and the temperature compensation term γ·ΔT is used to eliminate thermal interference. The σf calculated by the three terms can more realistically reflect the composite stress state of the flange end face, and at the same time has the ability to provide early warning.

[0102] In some examples, the three coefficients α, β, and γ can be calibrated separately for riser flanges of different materials and stored in the local parameter table of the control unit. During system initialization, the corresponding parameter set is automatically loaded based on the flange material of the target wellhead. In some examples, the control unit can also perform trend analysis on the historical data of σf, for example, by smoothing the raw stress data through moving average or Kalman filtering to distinguish the true stress trend from transient signal fluctuations.

[0103] In some embodiments of this disclosure, the control unit determines the wellhead lift drive type as one of the following three cases based on the combined relationship between relative displacement evolution data and composite stress evolution data: The first scenario is casing-driven lift: when the relative displacement evolution data reaches the preset displacement threshold and the composite stress evolution data simultaneously reaches the preset stress threshold, the wellhead lift drive type is determined to be casing-driven lift.

[0104] In this scenario, the pulsed eddy current system detected an upward shift in the casing coupling position, indicating that the deep casing underwent genuine axial uplift under thermal stress. This uplift force is transmitted to the riser through the wellhead device, causing axial compressive stress on the bottom flange face of the riser, possibly accompanied by bending stress. The magnetic stress system simultaneously monitored an increase in stress concentration on the flange face, with the stress direction consistent with the uplift direction. This situation represents casing-driven uplift from the inside out, and the root cause of the risk lies in the thermal expansion or deformation of the underground casing. Close attention must be paid to the integrity of the wellbore and the safety status of the casing coupling.

[0105] The second scenario is riser-driven lift: when the relative displacement evolution data does not reach the preset displacement threshold and the composite stress evolution data reaches the preset stress threshold, the wellhead lift drive type is determined to be riser-driven lift.

[0106] In this scenario, the pulsed eddy current system showed no change in the casing coupling position, indicating that the deep casing had not experienced actual uplift. However, the magnetic stress system detected increased stress on the bottom flange face of the riser, suggesting that the riser itself had deformed or uplifted due to thermal stress, mechanical stress, or external loads. The riser then transmitted the uplift force back to the wellhead equipment, causing the flange face to be overloaded. This situation represents a bottom-up, self-stressed uplift of the riser, and the root cause of the risk lies in the structural safety of the connection between the riser and the wellhead. Close attention should be paid to whether the flange bolts are overloaded and whether the seal has failed.

[0107] The third scenario is lift force release type lift: when the relative displacement evolution data reaches the preset displacement threshold and the composite stress evolution data does not reach the preset stress threshold, the wellhead lift drive type is determined to be lift force release type lift.

[0108] In this scenario, although the deep casing has been uplifted, the uplift force is partially released or buffered during its transmission to the riser. This could be due to flexible connections at the wellhead or relative slippage between the casing and the riser. The magnetic stress system detects a small increase in stress on the flange face, but the pulsed eddy current system has captured casing displacement. This situation suggests the need to inspect the integrity of the wellhead connections to prevent localized damage caused by uneven stress release.

[0109] In some scenarios, a fourth situation exists: neither the relative displacement evolution data nor the composite stress evolution data have reached their respective thresholds, but historical data records show that the thresholds have been exceeded in the past. In this case, it is necessary to conduct retrospective analysis in conjunction with time series data. It is possible that the uplift process has entered a stable period, the stress has been released, but the displacement remains permanent. By comparing historical data, it can be determined whether uplift has ever occurred and its evolution pattern.

[0110] In some examples, preset displacement thresholds and preset stress thresholds can be configured based on the specific engineering parameters of the target wellhead (such as casing specifications, flange material, design load, etc.) and stored in the parameter file of the control unit. In some examples, the system can also set multiple warning thresholds (such as warning level and alarm level). When the monitored value exceeds the warning threshold, a prompt is issued; when it exceeds the alarm threshold, an emergency alarm is issued, so that on-site personnel can respond in stages.

[0111] In some examples, the control unit can further distinguish the following disturbance scenarios: For internal pressure stress, which mainly causes circumferential stress on the flange end face (radial expansion inside the flange), the distribution pattern is different from that of lifting stress (axial tension or compression, with stress at each bolt position in the circumferential direction being basically symmetrical), and can be distinguished by analyzing the spatial distribution of stress; For changes in bolt preload, the changes are highly concentrated near a single bolt, and can be identified by comparing the signal differences at the positions of adjacent bolts; For high-frequency random stress fluctuations caused by vibration, they can be distinguished from quasi-static lifting stress trends by time-domain filtering.

[0112] See Figure 7 , Figure 7 This is a flowchart of a wellhead lift safety monitoring method provided in an embodiment of this disclosure. Specifically, it includes steps S702-S710.

[0113] Step S702: Acquire the secondary attenuated magnetic field signal generated by the bushing when the pulsed eddy current detection component emits a pulsed magnetic field to the bushing coupling area.

[0114] Specifically, the CPU of the pulsed eddy current detection component periodically controls the transmitting circuit to inject a bipolar step current into the transmitting coil, thereby generating a pulsed magnetic field around the bushing. The receiving coil continuously collects the secondary attenuated magnetic field signal, which is then processed by the signal conditioning circuit and transmitted to the control unit.

[0115] Step S704: Acquire the leakage magnetic field signal caused by the stress state of the riser flange connection area when the magnetic stress detection component locally magnetizes the riser flange connection area.

[0116] Specifically, the excitation coil of the magnetic stress detection component continuously establishes an alternating magnetic field in the U-shaped magnetic core, and the TMR magnetoresistive chip continuously collects the leakage magnetic field signal in the flange connection area, which is then transmitted to the control unit after low-pass filtering and amplification.

[0117] In some examples, the pulsed eddy current detection component and the magnetic stress detection component can operate in a time-sharing or synchronous manner under the unified scheduling of the control unit. In the time-sharing mode, the two systems alternately acquire data, which can avoid mutual electromagnetic interference; in the synchronous mode, the two systems acquire data simultaneously, which can obtain displacement and stress data at the same moment, which is beneficial for accurate analysis of time-series related events.

[0118] Step S706: Extract displacement characteristic parameters from the secondary attenuated magnetic field signal, and generate relative displacement evolution data of the sleeve coupling region relative to the pulse eddy current detection component based on the displacement characteristic parameters.

[0119] Specifically, the methods for extracting displacement characteristic parameters and generating relative displacement evolution data can be found in the above-mentioned embodiment of the wellhead lift safety monitoring device, and will not be repeated here.

[0120] Step S708: Extract stress characteristic parameters from the leakage magnetic field signal, and generate composite stress evolution data characterizing the mechanical state of the riser flange connection area based on the stress characteristic parameters.

[0121] Specifically, the methods for extracting stress characteristic parameters and generating composite stress evolution data can also be found in the above-mentioned embodiment of the wellhead lift safety monitoring device, and will not be repeated here.

[0122] Step S710: Determine the wellhead lift drive type of the target wellhead based on the combined relationship between relative displacement evolution data and composite stress evolution data.

[0123] Specifically, the logic for determining the drive type can also be found in the above-mentioned embodiment of the wellhead lift safety monitoring device, and will not be repeated here.

[0124] In some embodiments of this disclosure, the wellhead lift safety monitoring method can be continuously executed in a loop after the system is powered on. The sampling period can be configured according to on-site requirements, for example, completing a full acquisition and calculation cycle every few seconds to several minutes. In some examples, when the monitored displacement or stress value exceeds a preset threshold, the system can actively shorten the sampling period to improve the temporal resolution of the early warning.

[0125] Please refer to Figure 8 The wellhead lifting safety monitoring device can be composed of multiple logical or physical functional modules, which can be implemented through software programming. Figure 8 This is a schematic diagram illustrating the composition of the wellhead lift safety monitoring device provided in an embodiment of this disclosure. Figure 8 As shown, the wellhead lift safety monitoring device 800 includes: First acquisition module 802: is configured to acquire the secondary attenuated magnetic field signal generated by the bushing when the pulsed eddy current detection component emits a pulsed magnetic field to the bushing coupling area.

[0126] The second acquisition module 804 is configured to acquire the leakage magnetic field signal caused by the stress state of the riser flange connection area when the magnetic stress detection component locally magnetizes the riser flange connection area.

[0127] The first extraction module 806 is configured to extract displacement feature parameters from the secondary attenuated magnetic field signal and generate relative displacement evolution data of the sleeve coupling region relative to the pulse eddy current detection component based on the displacement feature parameters.

[0128] The second extraction module 808 is configured to extract stress characteristic parameters from the leakage magnetic field signal and generate composite stress evolution data characterizing the mechanical state of the riser flange connection area based on the stress characteristic parameters.

[0129] First determining module 810: Determines the wellhead lift drive type of the target wellhead based on the combined relationship between relative displacement evolution data and composite stress evolution data.

[0130] In some embodiments, the displacement characteristic parameters include amplitude and decay time constant. The amplitude is the voltage value corresponding to a fixed delay after the excitation of the pulse magnetic field is turned off, and the decay time constant is obtained by fitting the late signal segment of the secondary decay magnetic field signal with exponential decay.

[0131] In some embodiments, the relative displacement evolution data is generated based on the relative change of amplitude relative to a reference amplitude, the relative change of decay time constant relative to a reference decay time constant, the displacement weighting coefficient corresponding to the amplitude, the displacement weighting coefficient corresponding to the decay time constant, and the displacement temperature compensation.

[0132] In some embodiments, the reference amplitude, the reference attenuation time constant, the displacement weighting coefficient corresponding to the amplitude, the displacement weighting coefficient corresponding to the attenuation time constant, and the displacement temperature compensation amount are determined by calibration data, wherein the calibration data includes the amplitude, attenuation time constant, and temperature collected when the sleeve sample section and the coupling boss are in different relative positions with respect to the pulse eddy current detection component.

[0133] In some embodiments, the wellhead lift safety monitoring device 800 further includes a second determining module configured to: determine a first attenuation rate of the secondary attenuated magnetic field signal in an early time window and a second attenuation rate in a late time window; and, based on the ratio between the first attenuation rate and the second attenuation rate, distinguish whether the change in the secondary attenuated magnetic field signal relative to the reference secondary attenuated magnetic field signal is caused by displacement of the casing coupling area or by fluctuations in the casing permeability.

[0134] In some embodiments, stress characteristic parameters include static flux leakage change, flux leakage rate, and temperature change; composite stress evolution data are generated based on the product of static flux leakage change and static magnetic signal coefficient, the product of flux leakage rate and dynamic stress coefficient, and the product of temperature change and temperature compensation coefficient.

[0135] In some embodiments, the first determining module 810 is further configured to: determine the wellhead lift drive type as casing-driven lift when the relative displacement evolution data reaches a displacement threshold and the composite stress evolution data reaches a stress threshold; determine the wellhead lift drive type as riser-forced lift when the relative displacement evolution data does not reach a displacement threshold and the composite stress evolution data reaches a stress threshold; and determine the wellhead lift drive type as lift force release lift when the relative displacement evolution data reaches a displacement threshold and the composite stress evolution data does not reach a stress threshold.

[0136] Please refer to Figure 9 , Figure 9This is a schematic diagram illustrating the composition of a computer device according to an embodiment of the present disclosure. In some embodiments, the computer device 200 may include a processor 201, a memory 202, an input / output (I / O) interface 203, and a communication port 204. The processor 201 may include a microcontroller, a microprocessor, a reduced instruction set computer (RISC), an application-specific integrated circuit (ASIC), an application-specific instruction-set processor (ASIP), a central processing unit (CPU), a graphics processing unit (GPU), a physical processor (PPU), a microcontroller, a digital signal processor, a field-programmable gate array (FPGA), an advanced reduced instruction set system (ARM), a programmable logic device (PLD), any circuit or processor capable of performing at least one function, or any combination thereof.

[0137] Memory 202 may store data, instructions, and / or any other information. In some examples, memory 202 may store data acquired from the imaging device. In some examples, memory 202 may store data and / or instructions for performing the exemplary methods described in this disclosure. In some examples, memory 202 may include mass storage, removable memory, volatile read-write memory, read-only memory (ROM), non-volatile memory, and any combination thereof.

[0138] For example, mass storage devices may include hard disks, optical disks, solid-state drives, etc. Removable storage devices may include flash drives, floppy disks, optical disks, memory cards, compact disks, magnetic tapes, etc. Volatile read / write storage devices may include random access memory (RAM). RAM may include dynamic random access memory (DRAM), double-data-rate synchronous dynamic random access memory (DDR SDRAM), static random access memory (SRAM), thyristor RAM (T-RAM), and zero-capacitor RAM (Z-RAM), etc. ROM may include mask-programmed ROM (MROM), programmable ROM (PROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), optical disc ROM (CD-ROM), and digital multifunction disk ROM, etc. The memory 202 may also include various types of non-volatile memory, which is memory that can retain stored data after power loss. For example, non-volatile memory may include novel non-volatile memory chips such as NAND flash memory, NOR flash memory, embedded multimedia card (eMMC), universal flash memory (UFS), ferroelectric RAM (FRAM), phase change memory (PCM), resistive RAM (RRAM), and magnetoresistive RAM (MRAM); non-volatile memory may also include various non-transitory storage media such as solid-state drives (SSD, including PCIe SSD and NVMe SSD), hard disk drives (HDD), secure digital cards (SD cards), transfer flash cards (TF cards), compact flash cards (CF cards), universal serial bus flash drives (U flash drives), Blu-ray discs (BD-ROM), recordable optical discs (CD-R), rewritable optical discs (CD-RW), digital versatile recordable optical discs (DVD-R), and digital versatile rewritable optical discs (DVD-RW).

[0139] In addition, those skilled in the art will understand that the structure of the computer device 200 shown in the above figures does not constitute a limitation on the computer device 200. The computer device 200 may include more or fewer components than shown, or combine certain components, or have different component arrangements. For example, the computer device 200 may also include a display screen, camera assembly, microphone, speaker, radio frequency circuit, input unit, sensor, audio circuit, WiFi module, power supply, Bluetooth module, etc., which will not be described in detail here.

[0140] This disclosure also provides a non-volatile computer-readable storage medium storing at least one instruction that is executed by a processor to implement the wellhead lift safety monitoring method as described in the above embodiments.

[0141] This disclosure also provides a computer program product including computer instructions stored in a computer-readable storage medium; a processor of an electronic device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform the wellhead lift safety monitoring method described in the above embodiments.

[0142] Those skilled in the art will recognize that the functions described in this disclosure in one or more of the examples above can be implemented using hardware, software, firmware, or any combination thereof. When implemented in software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein communication media include any medium that facilitates the transfer of a computer program from one place to another. Storage media can be any available medium accessible to a general-purpose or special-purpose computer.

[0143] It should be noted that the technical solutions described in this disclosure can be combined arbitrarily as long as they do not conflict.

[0144] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A wellhead lift safety monitoring device, characterized in that, Includes a control unit, which is configured to: Acquire the secondary attenuated magnetic field signal generated by the bushing when the pulsed eddy current detection component emits a pulsed magnetic field to the bushing coupling area; The leakage magnetic field signal caused by the stress state of the flange connection area of ​​the water-proof pipe is acquired when the magnetic stress detection component locally magnetizes the flange connection area of ​​the water-proof pipe. Displacement feature parameters are extracted from the secondary attenuated magnetic field signal, and relative displacement evolution data of the sleeve coupling region relative to the pulse eddy current detection component are generated based on the displacement feature parameters. Stress characteristic parameters are extracted from the leakage magnetic field signal, and composite stress evolution data characterizing the mechanical state of the flange connection area of ​​the riser is generated based on the stress characteristic parameters. as well as The wellhead lift drive type of the target wellhead is determined based on the combined relationship between the relative displacement evolution data and the composite stress evolution data.

2. The wellhead lift safety monitoring device according to claim 1, characterized in that, The displacement characteristic parameters include amplitude and decay time constant. The amplitude is the voltage value corresponding to a fixed delay after the excitation of the pulse magnetic field is turned off. The decay time constant is obtained by performing exponential decay fitting on the late signal segment of the secondary decay magnetic field signal.

3. The wellhead lift safety monitoring device according to claim 2, characterized in that, The relative displacement evolution data is generated based on the relative change of the amplitude relative to the reference amplitude, the relative change of the decay time constant relative to the reference decay time constant, the displacement weighting coefficient corresponding to the amplitude, the displacement weighting coefficient corresponding to the decay time constant, and the displacement temperature compensation amount.

4. The wellhead lift safety monitoring device according to claim 3, characterized in that, The reference amplitude, the reference attenuation time constant, the displacement weighting coefficient corresponding to the amplitude, the displacement weighting coefficient corresponding to the attenuation time constant, and the displacement temperature compensation amount are determined by calibration data. The calibration data includes the amplitude, decay time constant, and temperature collected when the sleeve sample and the coupling boss are in different relative positions with respect to the pulse eddy current detection component.

5. The wellhead lift safety monitoring device according to any one of claims 1-4, characterized in that, The control unit is also configured to: Determine the first decay rate of the secondary decay magnetic field signal in the early time window and the second decay rate in the late time window; Based on the ratio between the first attenuation rate and the second attenuation rate, it can be distinguished whether the change in the secondary attenuated magnetic field signal relative to the reference secondary attenuated magnetic field signal is caused by the displacement of the bushing coupling area or by the fluctuation of the bushing permeability.

6. The wellhead lift safety monitoring device according to claim 1, characterized in that, The stress characteristic parameters include static flux leakage change, flux leakage change rate, and temperature change. The composite stress evolution data is generated based on the product of the static leakage flux change and the static magnetic signal coefficient, the product of the leakage flux change rate and the dynamic stress coefficient, and the product of the temperature change and the temperature compensation coefficient.

7. The wellhead lift safety monitoring device according to claim 1, characterized in that, The determination of the wellhead lift drive type of the target wellhead based on the combined relationship between the relative displacement evolution data and the composite stress evolution data includes: When the relative displacement evolution data reaches the displacement threshold and the composite stress evolution data reaches the stress threshold, the wellhead lift drive type is determined to be casing-driven lift. When the relative displacement evolution data does not reach the displacement threshold and the composite stress evolution data reaches the stress threshold, the wellhead lift drive type is determined to be riser-forced lift. When the relative displacement evolution data reaches the displacement threshold and the composite stress evolution data does not reach the stress threshold, the wellhead lift drive type is determined to be lift force release type lift.

8. A wellhead lift safety monitoring system, characterized in that, Includes a pulsed eddy current detection component, a magnetic stress detection component, and a control unit; The pulsed eddy current detection component is fixed relative to the riser at the target wellhead and arranged in accordance with the casing coupling area of ​​the target wellhead. The pulsed eddy current detection component is used to emit a pulsed magnetic field to the casing coupling area and collect the secondary attenuated magnetic field signal generated by the casing. The magnetic stress detection component is arranged in the riser flange connection area of ​​the target wellhead. The magnetic stress detection component is used to locally magnetize the riser flange connection area and collect the leakage magnetic field signal caused by the stress state of the riser flange connection area. The control unit is communicatively coupled to the pulsed eddy current detection component and the magnetic stress detection component, respectively. The control unit is configured to: Displacement feature parameters are extracted from the secondary attenuated magnetic field signal, and relative displacement evolution data of the sleeve coupling region relative to the pulse eddy current detection component are generated based on the displacement feature parameters. Stress characteristic parameters are extracted from the leakage magnetic field signal, and composite stress evolution data characterizing the mechanical state of the flange connection area of ​​the riser is generated based on the stress characteristic parameters. as well as The wellhead lift drive type of the target wellhead is determined based on the combined relationship between the relative displacement evolution data and the composite stress evolution data.

9. The wellhead lift safety monitoring system according to claim 8, characterized in that, The pulsed eddy current detection assembly includes a magnetic core, a transmitting coil, and a receiving coil. The transmitting coil and the receiving coil are wound in layers around the magnetic core. The transmitting coil is used to generate the pulsed magnetic field when a step current is applied, and the receiving coil is used to receive the secondary attenuated magnetic field signal.

10. The wellhead lift safety monitoring system according to claim 8, characterized in that, The magnetic stress detection assembly includes a U-shaped magnetic core, an excitation coil, a magnetic induction unit, and a magnetic shielding component. The excitation coil is wound around the U-shaped magnetic core and used to form a magnetic circuit in the flange connection area of ​​the water-proof pipe; the magnetic induction unit is used to collect the leakage magnetic field signal; the magnetic shield is disposed on the outside of the magnetic induction unit and is used to suppress the interference of the ambient magnetic field on the leakage magnetic field signal.

11. A method for monitoring wellhead lift safety, characterized in that, include: Acquire the secondary attenuated magnetic field signal generated by the bushing when the pulsed eddy current detection component emits a pulsed magnetic field to the bushing coupling area; The leakage magnetic field signal caused by the stress state of the flange connection area of ​​the water-proof pipe is acquired when the magnetic stress detection component locally magnetizes the flange connection area of ​​the water-proof pipe. Displacement feature parameters are extracted from the secondary attenuated magnetic field signal, and relative displacement evolution data of the sleeve coupling region relative to the pulse eddy current detection component are generated based on the displacement feature parameters. Stress characteristic parameters are extracted from the leakage magnetic field signal, and composite stress evolution data characterizing the mechanical state of the flange connection area of ​​the riser is generated based on the stress characteristic parameters. as well as The wellhead lift drive type of the target wellhead is determined based on the combined relationship between the relative displacement evolution data and the composite stress evolution data.

12. A non-volatile computer-readable storage medium, characterized in that, The non-volatile computer-readable storage medium stores at least one instruction, which is executed by a processor to implement the wellhead lift safety monitoring method as described in claim 11.

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