Underwater well repair system

Abstract

The invention provides an underwater well repair system, and relates to the technical field of underwater well repair intervention equipment. The system comprises a monitoring module used for collecting monitoring data of an operation site and preprocessing the monitoring data, the monitoring data comprising environmental data, operation data and sea condition data; the risk assessment module is used for calculating current risk assessment information according to the preprocessed monitoring data; the control module is used for generating an emergency release instruction or a reentry instruction according to the risk assessment information; and the execution module is used for receiving the emergency release instruction or the reentry instruction and controlling the underwater workover tool to act according to the emergency release instruction or the reentry instruction so as to protect the underwater workover tool. According to the embodiment of the invention, the dependence on personal experience can be effectively reduced, the operation threshold is reduced, the response speed is high, the reliability is high, the probability of equipment damage is reduced, and the safety and the operation efficiency of an underwater well repair tool under severe sea conditions are greatly improved.

Description

Technical Field

[0001] This application relates to the field of underwater well workover intervention equipment technology, and more specifically, to an underwater well workover system. Background Technology

[0002] As offshore oil and gas field development gradually expands into deeper waters and complex sea conditions, the demand for Light Well Intervention (LWI) operations is increasing. These operations rely on multi-functional support vessels or lightweight platforms equipped with dynamic positioning (DP) systems to deliver subsea workover tools and control media into the wellbore via umbilical cables or lightweight risers to perform tasks such as valve maintenance, sand removal, injection, and testing.

[0003] However, during operations, the superposition of complex waves and swells can easily cause phenomena such as heave, roll, and pitch coupling of the hull or platform, applying periodic or sudden axial and lateral loads to the riser and the tool ends of the underwater workover tools. Excessive loads can easily damage the underwater workover tools. To address this issue, existing technologies rely on operators sensing sea conditions and controlling the underwater workover tools to perform emergency release or reentry operations based on the sensing results. This method heavily depends on the experience of the operators, has a high operational threshold, and the manual sensing method lags behind actual sea conditions, easily leading to operational delays, equipment damage, and high operational risks. Summary of the Invention

[0004] This application provides an underwater well repair system that can solve the problems of existing manual control methods that rely heavily on personal experience, have high operational thresholds, and are prone to operational delays, equipment damage, and high operational risks.

[0005] To achieve this objective, the embodiments of this application provide the following solutions.

[0006] According to one aspect of the embodiments of this application, a subsea well workover system is provided, the system being connected to a subsea well workover tool, comprising: The monitoring module is used to collect monitoring data at the work site and preprocess the monitoring data, which includes environmental data, work data, and sea state data. The risk assessment module is used to calculate the current risk assessment information based on the preprocessed monitoring data; The control module is used to generate an emergency release command or a re-entry command based on the risk assessment information. The execution module is used to receive the emergency release command or re-entry command and control the underwater well workover tool to operate according to the emergency release command or re-entry command in order to protect the underwater well workover tool.

[0007] In one possible implementation, a data storage and update module is also included. The data storage and update module is used to record the execution data of the execution module, as well as the emergency and / or re-entry action information and alarm information, and to perform trend analysis and data updates based on the execution data, action information and alarm information.

[0008] In one possible implementation, the risk assessment information includes risk data and risk probability, wherein the calculation of the risk probability includes: Based on the monitoring data, the risk data corresponding to the underwater well repair tool is calculated, and the risk data includes the predicted heave value, tension change rate, and offset change rate. The risk probability is calculated based on the risk data, and the formula for calculating the risk probability is:

[0009] In the formula, For risk probability, , These are the weighting coefficients. For normalized tension, The rate of change of tension, It is the rate of change of offset; It is a predicted heave / sag value; It is the percentage of the effective field of view; It's the health of the communication. This is the sigmoid function.

[0010] In one possible implementation, the subsea workover tool includes a release mechanism for connection to the subsea wellhead and a redundancy mechanism. The generation of the emergency release command includes: Based on the risk data, a combined risk index is calculated, and based on the combined risk index and the risk probability, the release mechanism and the redundant mechanism are controlled to perform preparatory actions. If the interlocking conditions are determined to be met based on the monitoring data and the risk data, an emergency unlocking command is generated to instruct the release mechanism to operate.

[0011] In one possible implementation, the risk data includes dynamic trigger probabilities, and the formula for calculating the combined risk index is:

[0012] In the formula, , , , , , These are the weighting coefficients; The preparatory actions performed by the release mechanism and the redundant mechanism based on the combined risk indicators and the risk probability control include: If it is determined that the combined risk index is greater than or equal to the index threshold and the risk probability is greater than or equal to the dynamic trigger threshold, then an instruction to perform a preparatory action is sent to the execution module.

[0013] In one possible implementation, the subsea wellhead is equipped with a well control linkage module for sealing the subsea wellhead, which controls the operation of the subsea workover tool according to the emergency release command, including: Control the release mechanism to disconnect from the underwater wellhead and obtain the stroke information corresponding to the release mechanism; If a jam is determined based on the travel information, the redundant mechanism is used to disconnect the tool end of the underwater workover tool from the underwater wellhead, and the well control linkage module is controlled to close the underwater wellhead.

[0014] In one possible implementation, the generation of the reentrancy instruction includes: The dominant strategy is determined based on the monitoring data. The position of the working end of the underwater workover tool is adjusted based on the acoustic data and optical data in the monitoring data and the dominant strategy. The dominant strategy includes an optical dominant strategy and an acoustic dominant strategy. If the alignment conditions are met based on the position, a reentry command is generated to instruct the tool end of the subsea workover tool to engage with the subsea wellhead.

[0015] In one possible implementation, determining the dominant strategy based on the monitoring data includes: The optical quality score and acoustic signal-to-noise ratio are calculated based on the monitoring data. The dominant strategy is determined based on the comparison results of the optical quality score and the quality score threshold, and the comparison results of the acoustic signal-to-noise ratio and the minimum acoustic signal-to-noise ratio threshold. The formula for calculating the optical quality score is:

[0016] In the formula, To rate the optical quality, The number of effective feature points, The desired number of feature points, Rate the contrast ratio. , These are weighting coefficients. + =1.

[0017] In one possible implementation, the alignment condition includes that the deviation of the tool end in the underwater workover tool is not greater than a predetermined threshold, and the deviation includes planar position error and angular error; The formula for calculating the deviation is:

[0018]

[0019] In the formula, For planar position error, For angular error, The planar position of the tool end, ( () is the plane position of the reference point. , , These are the weighting coefficients. The roll angle error at the tool end. The pitch angle error at the tool end. This refers to the yaw angle error at the end of the tool.

[0020] In one possible implementation, controlling the underwater workover tool's movements according to a reentry command includes: The tool end is controlled to lock with the subsea wellhead based on the graded velocity curve, and the force information of the tool end is obtained during the locking process. The locking is adjusted according to the force information, which includes lateral force and axial insertion force. The expression for the graded velocity curve is:

[0021] In the formula, The axial velocity corresponding to the insertion depth of the tool end is s, where s is the insertion depth. As the segment boundary, This represents the maximum insertion speed.

[0022] The beneficial effects of the technical solutions provided in this application are: The underwater well workover system provided in this application includes: a monitoring module for collecting monitoring data at the work site and preprocessing the monitoring data, which includes environmental data, operational data, and sea state data; a risk assessment module for calculating current risk assessment information based on the preprocessed monitoring data; a control module for generating emergency release or re-entry commands based on the risk assessment information; and an execution module for receiving emergency release or re-entry commands and controlling the underwater well workover tool's actions according to the commands to protect the tool. This application's embodiment automatically collects monitoring data related to well workover tool operations, performs risk assessments based on this data, and controls the underwater well workover tool's actions based on the assessment results. This effectively reduces reliance on personal experience, lowers the operational threshold, and offers fast response and high reliability, reducing the probability of equipment damage and significantly improving the safety and operational efficiency of underwater well workover tools in harsh sea conditions. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments of this application will be briefly introduced below.

[0024] Figure 1 A block diagram of an underwater well repair system provided in an embodiment of this application; Figure 2 A flowchart of an emergency escape procedure provided for an embodiment of this application; Figure 3 A flowchart illustrating wellbore reentry provided in this application embodiment; Figure 4 A flowchart illustrating multimodal fusion and weight adaptation provided in this application embodiment; Figure 5 A schematic diagram of a portion of the structure of the release mechanism provided in the embodiments of this application; Figure 6 This is a schematic diagram of the state machine logic control mechanism provided in the embodiments of this application. Detailed Implementation

[0025] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0026] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the terms “comprising” and “including” as used in embodiments of this application mean that the corresponding feature can be implemented as the presented feature, information, data, step, operation, element, and / or component, but do not exclude implementation as other features, information, data, step, operation, element, component, and / or combinations thereof supported by the art. It should be understood that when we say that an element is “connected” or “coupled” to another element, the one element can be directly connected or coupled to the other element, or it can mean that the one element and the other element establish a connection relationship through an intermediate element. Furthermore, “connected” or “coupled” as used herein can include wireless connection or wireless coupling. The term “and / or” as used herein indicates at least one of the items defined by the term; for example, “A and / or B” indicates implementation as “A,” or implementation as “A,” or implementation as “A and B.”

[0027] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0028] The technical solutions of the embodiments of the present invention and the technical effects produced by the technical solutions of the present invention will be described below through several exemplary embodiments. It should be noted that the following embodiments can be referred to, learned from, or combined with each other, and the same terms, similar features, and similar implementation steps in different embodiments will not be described again.

[0029] The underwater well repair system provided in this application is intended to solve at least one technical problem existing in the prior art.

[0030] This application provides an underwater well repair system, such as... Figures 1-6 As shown, the subsea workover system can be connected to subsea workover tools and includes: a monitoring module for collecting monitoring data at the work site and preprocessing the monitoring data, which includes environmental data, operational data, and sea state data; a risk assessment module for calculating current risk assessment information based on the preprocessed monitoring data; a control module for generating emergency release commands or re-entry commands based on the risk assessment information; and an execution module for receiving emergency release commands or re-entry commands and controlling the subsea workover tools to protect them.

[0031] Optionally, environmental data may include acoustic (long baseline LBL / ultra-short baseline USBL) data and optical data at the work site. Work data may include inertial navigation / motion reference unit (IMU / MRU) data, tension, pressure, and acceleration data. Sea state data may describe sea surface fluctuations (such as significant wave height and dominant period). The acoustic and optical data may describe the location of the subsea workover tool and the subsea wellhead reference point (connection reference point). The inertial navigation / motion reference unit and acceleration data can be obtained from sensors installed on the work vessel or platform connected to the subsea workover tool. The tension and pressure data may be data on the tension and pressure experienced by the riser / subsea workover tool (tool string) used to connect to or place the subsea workover tool.

[0032] In one embodiment, the monitoring module acquires inertial navigation / motion reference unit (IMU / MRU) data, which includes triaxial angular velocities. Triaxial acceleration Posture Quaternion The real-time heave displacement h is obtained through a tension sensor, which measures the instantaneous tension on the riser or tool string. This instantaneous tension is then normalized. The normalization calculation formula can be... . Design safety tension for riser / subsea workover tools.

[0033] Acoustic data can be used for acoustic positioning. The acoustic positioning sensors in the system output absolute (or relative) position data of the tool tip or underwater wellhead reference point at low frequencies (0.2~2 Hz). The position in this data can be represented as... , Representing three-dimensional coordinates, the covariance matrix corresponding to a position in location data can be expressed as: , The observation covariance of the acoustic positioning sensor output is calculated.

[0034] Optical data can be obtained through cameras or structured light. This optical data includes attitude measurements of the subsea workover tool tip relative to a wellhead feature plane or target, and the results can be expressed as follows: The result includes the translation of the tool tip relative to the reference point on the xyz axes. and the attitude error of the tool relative to the predetermined attitude. Environmental data may also include the velocity of the ship or platform relative to the seabed, which is obtained through DVL (Doppler velocimeter).

[0035] Optionally, the operational data may include communication status monitoring data and visual effective field data, which may include packet success rate (the success rate of data packet transmission). Round trip delay With shaking Normalizing these data yields the communication quality index Q_comm. The visual effective field includes the percentage of effective pixels. The wave state can be determined based on the proportion of feature points (used for image recognition and localization) in the captured image that meet the requirements (confidence greater than a set optical confidence threshold). Sea state data can include effective wave heights obtained through wave radar or existing environmental models. Dominant Cycle .

[0036] Optionally, the subsea workover tool may include a release mechanism and a redundancy mechanism for connection to the subsea wellhead. The release mechanism may include a wedge lock and a shear sleeve. The wedge lock is connected to the shear sleeve. After the release mechanism is connected to the subsea wellhead via a pin connected to the shear sleeve, the wedge lock self-locks to prevent disconnection. When rapid disconnection is required, the wedge lock retracts, thereby causing the shear sleeve to shear the pin and achieve emergency release. Correspondingly, the operational data may also include the retraction stroke of the wedge lock in the release mechanism. Stroke of shear sleeve moving upward and the insertion depth after the release mechanism re-enters. .

[0037] Optionally, the execution module may include a well control linkage module, which may be equipped with a packer or connector. The operational data includes the pressure of the internal cavity (packer cavity or test cavity) of the packer or connector. The working status of the well control linkage module is detected by this pressure.

[0038] Optionally, preprocessing includes time alignment, filtering, and coordinate system unification of the monitoring data for subsequent use. During time alignment, acoustic, optical, and IMU / MRU data can be preprocessed. Preprocessing methods include unifying the time scale of each mode (acoustic, optical, and IMU / MRU modes) and establishing a master time axis, which can be represented as follows: ( The fusion operation cycle for each modality, (for discrete-time indexing) The time interval can be 10~20 ms. For low-frequency acoustic measurements, the interval is within this range. Internally, zero-order hold or prediction updates based on inertial propagation are employed. In the event of temporary optical frame loss, inertial propagation plus the most recent optical correction can be used to construct an extrapolated estimate of the lost frame.

[0039] In one embodiment, when unifying the coordinate system, a volume coordinate system can be established. Tool end (tool end of the release mechanism, used for insertion with the subsea wellhead) coordinate system Wellhead reference coordinate system Inertial (Earth-fixed) coordinate system , via attitude quaternion With rigid transformation (The attitude quaternion is transformed using a rigid transformation matrix), the attitude is derived from... Complete rotation to unify The tool end state of the release mechanism is obtained in the coordinate system. Preliminary estimate based on optical data output. relatively The pose residuals are uniformly converted into a coordinate system. This will then be used as the update amount.

[0040] Optionally, the risk assessment information includes risk data, wherein the calculation of risk probability includes: calculating the risk data corresponding to the underwater well repair tool based on monitoring data, and the risk data includes predicted heave value, tension change rate and offset change rate; The risk probability is calculated based on the risk data. The formula for calculating the risk probability is:

[0041] In the formula, For risk probability, , These are the weighting coefficients. For normalized tension, The rate of change of tension, It is the rate of change of offset; It is a predicted heave / sag value; It is the percentage of the effective field of view; It's the health of the communication. This is the sigmoid function. .

[0042] Optionally, when calculating risk data, tension and offset (offset) can be calculated first. The horizontal displacement amplitude of the tool tip relative to the wellhead reference point is determined by data fusion from acoustic, optical, and inertial / motion reference units to obtain the positions of the tool tip and the reference point, thus yielding the offset value, heave data, and quality factor prediction. These data can be predicted in the short term (e.g., time length of [missing information]) using a sliding window smoothing method. The changing trend within )

[0043] In one embodiment, rapid spectral analysis combined with an autoregressive (AR) model or a short-sequence prediction model can be used to obtain the predicted heave values. , among which, in the time window Used By fitting the model, a prediction model for heave and sag values ​​is obtained, and future time periods are extrapolated based on this model. The changes in heave and sag are observed to obtain the predicted heave and sag values, and to estimate the peak heave and sag values ​​for the next 2-4 seconds. The rate of change can be obtained by performing sliding regression (such as local linear regression or difference smoothing) on ​​tension and offset.

[0044] Specifically, it can be done through Data acquisition of heave signals For this signal, take the nearest window. (length ), establish an autoregressive model, the order of the model The expression for an autoregressive model This model is used to predict future time periods. The peak values ​​of heave and sag within the range are used to obtain the predicted heave and sag values. In the formula, For coefficients, The sampling period; It is noise.

[0045] ,in, This represents the heave or sag at a future time t+τ.

[0046] In one embodiment, the offset change rate and the tension change rate are calculated in the same way, wherein the tension change rate... Local linear regression (window) Alternatively, it can be calculated using difference smoothing. The calculation formula can be:

[0047] In the formula, For time-domain Gaussian weights, , The standard deviation is the time-weighted standard deviation. For the first One tension sample, Let be the mean tension value within the time window corresponding to the k-th tension sample. For the first Each sampling time, This is the average tension value corresponding to the kth sampling time (e.g., the average tension value between the kth sampling time and the (k+1)th sampling time).

[0048] Optionally, the generation of the emergency release command includes: calculating a combined risk index based on risk data; controlling the release mechanism and redundant mechanism to perform preparatory actions based on the combined risk index and risk probability; and generating an emergency unlock command that instructs the release mechanism to act if the interlocking conditions are met based on monitoring data and risk data.

[0049] Optionally, the risk data may include dynamic trigger probabilities, and the formula for calculating the combined risk indicators may be:

[0050] In the formula, , , , , , These are the weighting coefficients.

[0051] The preparatory actions, based on the combined risk indicators, risk probability control release mechanism, and redundancy mechanism, include: if it is determined that the combined risk indicator is greater than or equal to the indicator threshold and the risk probability is greater than or equal to the dynamic trigger threshold, then an instruction to execute the preparatory actions is sent to the execution module. (Indicator threshold) and (Dynamic trigger probability) The instruction to execute the preparatory action is sent only if the conditions are met simultaneously.

[0052] Optionally, the risk data may also include early warning probabilities, which can be calculated as risk probabilities. and the probability of warning Dynamic trigger probability A comparison is made, and if the warning probability is reached, the parameter pre-adjustment action is initiated immediately but the release is not triggered. If the dynamic trigger probability is reached and the trend continues (e.g., instantaneously exceeding...), the trigger probability is reached. The length of the time slice set is Only when (A trigger time of 0.8~1.2 s is considered valid to prevent transient noise), then the preparatory action is executed. Dynamic trigger probability. Based on the effective wave height Hs, the offset amplitude, and the optical failure rate (in terms of...), (Measure optical failure rate) and make linear or nonlinear adjustments to ensure that the threshold decreases moderately to improve sensitivity when the environment deteriorates.

[0053] In one embodiment, the formula for calculating the dynamic trigger probability can be:

[0054] in, The mean of the quality factor. , For the i-th quality factor, The total number of quality factors. For reference to the effective wave height, For the effective wave height, For offset, To allow the maximum offset magnitude, ; ; ; .

[0055] Optionally, the probability of an early warning is less than the probability of dynamic triggering, wherein the probability of an early warning is less than the probability of dynamic triggering. The calculation formula can be:

[0056] .

[0057] Optionally, the preparatory actions may include preparatory actions for controlling the release mechanism and the redundant mechanism to perform emergency release. The release mechanism is equipped with a hydraulic main circuit for providing power, and the redundant mechanism is equipped with an electric push rod and a burst-cut assembly for disconnecting the workover tool from the subsea wellhead. The preparatory actions may include hydraulic pre-charging of the hydraulic main circuit and unlocking of the redundant mechanism.

[0058] Specifically, hydraulic pre-charging includes increasing the pressure in the main hydraulic circuit. Increase work pressure ahead of schedule The values ​​are 0.85~0.92. This method reduces the response dead zone.

[0059] Redundant path unlocking includes a power-on self-test of the electric actuator of the redundant mechanism (used to retract the wedge lock of the release mechanism) (current baseline can be performed). Measurements are taken to monitor for normal operation. The burst-cut assembly (used to shear the weak ring / pin connecting the workover tool to the wellhead for rapid release) releases the safety short-circuit plate. The electric pushrod provides a redundant path for emergency release, applying force directly to the back of the wedge lock or replacing the main circuit to perform wedge lock retraction.

[0060] In one embodiment, such as Figure 5 As shown, the release mechanism consists of a housing, wedge lock, shearing sleeve, actuator piston, return spring, encoder, gear ring, sealing ring, guide sleeve, and pin. The main hydraulic circuit pushes the wedge lock back along the wedge angle formed by the hydraulic piston, releasing the radial clamping (releasing the radial clamping of the wedge lock on the connector used to connect the workover tool and the subsea wellhead), and then the shearing sleeve cuts the pin upwards, achieving instantaneous decoupling of the load path.

[0061] During wedge retraction, the angle between the wedge lock and one end of the actuator piston is maintained between 8° and 12° to balance the forces required for self-locking and retraction. A return spring keeps the released components (wedge lock, shear sleeve) separated, preventing re-engagement. Redundant mechanisms may include an electrically driven push rod that directly applies force to the back of the wedge lock, or a burst-cut assembly for shearing structural thin rings. A stroke encoder, along with hydraulic and current signals, jointly determines the stroke; success is achieved when the expected stroke is reached and the load does not rise abnormally. If the stroke stalls and the pressure increases, the determination is stuck, and the redundant mechanism provides emergency release. Sealing rings and guide sleeves ensure coaxiality of moving parts and prevent seawater ingress. The quick-release flange and viewing window (located on the release mechanism housing for easy maintenance and observation) facilitate maintenance and rapid replacement at sea. Common failures (hydraulic circuit leakage, encoder disconnection, wedge surface contamination) are mitigated by redundant drive, alternative stroke estimation, and a preparatory period micro-vibration cleaning strategy, respectively.

[0062] Optionally, wedge angle This makes the static friction self-locking satisfy ( (where the coefficient of static friction is 1), and to ensure reversibility under controlled hydraulic pressure during wedge lock retraction, the actual coefficient is taken as... .

[0063] Optionally, the dynamic positioning system (DP) of the hull or platform utilizes the thrusters and control computer to maintain the hull / platform's position and heading. The workover system can also include a heave compensation controller, which compensates for the relative displacement transmitted to the tool end through mechanical / hydraulic / control means. During preparatory actions, the heave compensation controller (which can calculate the heave compensation control output using conventional PID or acceleration feedforward control methods before introducing feedforward) introduces feedforward, switching the heave compensation control output to a high-sensitivity mode that includes a heave feedforward component. This improves the stability of the hull or platform, reduces the impact on the subsea workover tool, and minimizes the displacement of the tool end relative to the subsea wellhead reference point. The relevant calculation formula is: , For heave feedforward components, This is the feedforward gain. for The heave and displacement at any given moment. And when performing the preparatory action, the interlock flag is set, and the packer of the well control linkage module (used to establish a seal at the subsea wellhead) performs pre-centering and pressure preparation.

[0064] Heave compensation control output ,in, This is the feedback component (the feedback component of a conventional PID or acceleration feedforward type).

[0065] Optionally, the interlocking conditions may include probability preservation conditions, combined risk indicator conditions, communication health conditions, well control preparation conditions, and structural safety conditions. Specifically, the expression for the probability preservation condition is: , This refers to the moment when the probability of risk is greater than the dynamic trigger probability. The conditions for the combined risk indicator are: ( The communication health conditions are: ( The minimum communication health score can be 0.75. Well control preparation conditions include: the signal value of the packer pre-alignment signal in the well control linkage module. Pressure of pneumatic / hydraulic accumulators used for valve actuation ( (Minimum energy storage pressure). Structural safety conditions include: ( (At the limit of safety tension threshold) and without overload fatigue alarm, The normalized tension is the sum of the real-time tension T and the design safety tension of the riser (or tool string). The ratio, =T / .

[0066] Optionally, the underwater workover tool is controlled to move according to the emergency release command, including: controlling the release mechanism to disconnect from the underwater wellhead and obtaining the stroke information corresponding to the release mechanism; if jamming is determined according to the stroke information, the redundant mechanism is used to disconnect the tool end of the underwater workover tool from the underwater wellhead, and the well control linkage module is controlled to close the underwater wellhead.

[0067] Optionally, part of the structure of the release mechanism is as follows: Figure 5 As shown, when disconnecting using the release mechanism, the wedge lock can be controlled to retract axially along the inclined plane via the hydraulic main circuit, releasing the radial clamping and causing the shearing sleeve to move upward synchronously to cut off the pin. The stroke encoder monitors the displacement curves (piston retraction curve and shearing sleeve displacement curve) to determine whether the minimum safe stroke has been reached and to check for jamming characteristics. If the main circuit fails, the connection is cut off using the electric drive push rod of the redundant mechanism or the burst-cut assembly.

[0068] In one embodiment, the theoretical axial force required for wedge lock retraction is... The formula for calculation is:

[0069] in, The normal force on the wedge surface, the wedge angle coefficient of friction The output force of the release mechanism's actuator piston is... , For mechanical efficiency, , This is the effective pressure-bearing area of ​​the piston. This refers to the pressure in the cylinder chamber (the chamber that drives the piston). This output force must meet the following requirements. Safety margin .

[0070] Optionally, the diameter of the piston is... It can be calculated using the following formula:

[0071] In the formula, This refers to the working hydraulic pressure of the main hydraulic circuit.

[0072] Optionally, if n pins that can be sheared by the shearing sleeve are used, the bearing shear strength of each pin is... The cross-sectional area is Then the total shear load for:

[0073] Required , For operating load, The additional safety factor increment (dimensionless) on the shear strength side is used to amplify the operating load or reduce the conservative coefficient of the strength assessment. When shearing, the characteristic "decline-stable" segment of the hydraulic pressure in the main hydraulic circuit is used as an auxiliary criterion for judging whether the shearing was successful.

[0074] Optionally, the resolution of the travel encoder This resolution is used to set the capture lag characteristics. If the encoder fails, the travel is estimated using a time-stress model, which is as follows:

[0075] In the formula, This is an empirical coefficient. The threshold pressure.

[0076] Optionally, the wedge lock retraction stroke is obtained through the stroke encoder of the release mechanism. The theoretically expected trajectory is divided into two segments (acceleration / stability): if detected... (Approaching 0) and Rise, rise by more than Then it is determined to be stuck, where, This refers to the hydraulic main circuit pressure. The pressure increment for sluggishness detection.

[0077] like If the retraction is successful, then the retraction is confirmed. For the total itinerary, For minimum safe travel, This indicates that there is no blockage.

[0078] Optionally, upon determining a jam, the redundant mechanism is triggered. Specifically, if the hydraulic main path action times out or stall=true (indicating a jam is detected), the electric actuator of the redundant mechanism is activated. The timeout can be expressed as... , For execution time, This is the maximum allowed execution time.

[0079] Optionally, when the electric drive actuator actuates, the monitoring current related to the electric drive actuator is acquired. With speed If the monitored current increases and the speed decreases, it indicates that the friction limit is approaching. The power supply duty cycle (current limiting) should be increased accordingly to ensure that the current does not exceed the monitored current threshold. If the safety interlock conditions are met (the evacuation route to the subsea wellhead is cleared, and no personnel are exposed within the influence range of the explosive cutting assembly), then the explosive cutting mode can be entered. The explosive cutting assembly can be controlled to activate, and an initiation signal can be applied to it. This impacts and shears the thin ring on the connection structure between the workover tool and the subsea wellhead, causing the wedge lock to retract rapidly. Correspondingly, the stroke... Instantaneous jump ( This represents the abrupt change in displacement. (Using the minimum mutation criterion), after the redundant mechanism has finished its operation, a command is sent to instruct the well control linkage module to operate.

[0080] In one embodiment, when controlling the operation of the redundant mechanism, the electric drive push rod and the burst-cutting assembly can be limited, wherein the peak force of the electric drive push rod is... Thermal limit duration of electric actuator satisfy . : Motor / Push Rod Thermal Limit Current For thermal assessment time window The root mean square current within.

[0081] Execution time of burst cut component After the pin is cut, the displacement jump of the wedge lock satisfies , The minimum mutation criterion can be 5-8 mm. This represents the abrupt change in displacement.

[0082] Optionally, to achieve environmental protection, the pressure resistance of the sealing ring is... ≥The sum of the maximum offshore static water pressure and the seawater dynamic pressure. An anti-corrosion coating can be added to the wedge surface to reduce wedge lock damage. Micro-vibration cleaning can be performed during the preparatory phase, during which the wedge lock can be driven to reciprocate at low amplitude. (0.2~0.4 mm, 2~3 Hz, duration 1~2 s) to reduce particle adhesion, can be driven by a hydraulic main circuit / redundant mechanism.

[0083] Optionally, after receiving the command, the well control linkage module controls the packer to close to achieve wellhead sealing, and verifies the success of the sealing through pressure verification. The formula for pressure verification can be: and

[0084] In the formula, The pressure in the packer cavity formed by the packer. To isolate the verification time window, The minimum pressure rise rate threshold. To minimize the pressure to meet the standards.

[0085] Optionally, after successful emergency escape, the data storage and update module saves the risk probability trajectory, escape execution time, modal weights, and heave prediction errors, and then proceeds with the evacuation procedure. Anomaly suppression mechanisms address instantaneous spike probabilities (this probability is determined by...). Exceed Duration Judgment, shorter than Duration filtering (without triggering) ensures that transient noise does not escalate into actual action. In the event of partial sensor failure, data updates include weight allocation, i.e., according to... Reassignment, and restrict the release action unless triggered by hardware limitations. It is the i-th quality factor; It is the standard deviation of the i-th residual. The fusion weights (i.e., the time-domain Gaussian weights) for the i-th mode are used to calculate parameters such as tension and offset.

[0086] In one embodiment, the fields recorded by the data storage and update module include risk probability, dynamic trigger probability, combined risk index, wedge lock stroke, cylinder pressure corresponding to the executing piston, and release mode. Data such as (main path / redundancy), communication health, and quality factors at different times are used for retraining. Based on this data, a simple radial avoidance method can be adopted for the well workover tool's withdrawal path. The withdrawal speed can be calculated using the following formula:

[0087] In the formula, For the evacuation velocity vector, The unit direction vector is the distance from the wellhead. For the evacuation speed amplitude, (Adjustable according to sea conditions), maintain the tool's attitude locked during evacuation. ).

[0088] Optionally, after the subsea workover tool detaches from the subsea wellhead, a wellbore re-entry operation can be performed to reinsert the tool into the wellbore, completing the connection between the workover tool and the wellhead. The generation of the re-entry command includes: determining a dominant strategy based on monitoring data; adjusting the position of the working end of the subsea workover tool based on acoustic and optical data from the monitoring data and the dominant strategy; the dominant strategy includes an optical dominant strategy and an acoustic dominant strategy; if the alignment conditions are met based on the position, a re-entry command is generated instructing the tool end of the subsea workover tool to lock into the subsea wellhead.

[0089] Optionally, before determining the dominant strategy based on monitoring data, it can be determined whether a detachment operation was performed on the subsea wellhead before the reentry operation to be performed. If not, the dominant strategy is determined based on the monitoring data. If not, the wellhead reference frame before the last detachment is loaded first, the acoustic baseline is reset based on the wellhead reference frame, time synchronization and sound velocity are updated, and the optical cleanliness and focal length of the camera / window at the tool end are detected, IMU zero bias is estimated, and acoustic signal-to-noise ratio is evaluated based on the wellhead reference frame. After the above processing, the "optical dominant" or "acoustic dominant" strategy is determined according to the water transparency and multipath situation.

[0090] Optionally, the dominant strategy is determined based on the monitoring data, including: calculating the optical quality score and acoustic signal-to-noise ratio based on the monitoring data, and determining the dominant strategy based on the comparison results of the optical quality score and the quality score threshold, and the comparison results of the acoustic signal-to-noise ratio and the minimum acoustic signal-to-noise ratio threshold.

[0091] The formula for calculating the optical quality score is:

[0092] In the formula, To rate the optical quality, The number of valid feature points (the confidence level of the feature points is greater than the preset optical confidence threshold). The desired number of feature points, Rate the contrast ratio. , These are weighting coefficients. + =1.

[0093] Optionally, if Then the dominant strategy is determined to be the optical dominant strategy. As a quality scoring threshold, if Then, the dominant strategy is determined to be the acoustic dominant strategy, and the fusion window is extended (this window is the time window for observation smoothing and quality assessment, serving the period). renew), This is the minimum acoustic signal-to-noise ratio threshold.

[0094] Optionally, after determining the dominant strategy, the weights of acoustic data and optical data are determined based on the dominant strategy when determining the fusion positioning (the position of the acquisition tool and the reference point).

[0095] In one embodiment, during multimodal fusion, an extended Kalman filter (EKF) is used to establish a state vector, which is then used for... Prediction / Update. The state vector x can be:

[0096] In the formula, This refers to the positional component of the tool tip of the workover tool relative to the underwater wellhead reference point. This refers to the velocity component of the tool tip of the workover tool relative to the underwater wellhead reference point. The attitude quaternion components of the workover tool tip relative to the subsea wellhead reference point. ; For attitude quaternion constraint processing, the constraint conditions can be: .

[0097] For time synchronization, a unified clock and delay correction are used (acoustic data is updated at low frequencies, and time alignment and delay compensation are achieved based on the updated data; for optical data experiencing brief frame drops, inertial extrapolation is used for prediction, and correction is performed in the next valid frame) to handle acoustic low-frequency updates and possible brief frame drops in optical data. The residual of each mode is used to calculate its residual Mahalanobis distance statistic. The number of times the value exceeds a set threshold reaches a predetermined number is used to adjust the quality factor. decay, weight Then it was restored to its original state.

[0098] In one embodiment, the position and velocity components in the state vector can be predicted using inertial extrapolation, and the relevant calculation formula is as follows:

[0099]

[0100] in, For quaternions The generated rotation matrix, This is an IMU acceleration measurement. For accelerometer bias, The vector of gravitational acceleration. For fusion computing cycles, Let k be the speed of the tool at time k-1. For the predicted velocity at time k, The position at time k-1, This represents the predicted position at time k.

[0101] An observation set is generated based on optical data, acoustic data, and DVL observation results, and this observation set is used for... Update. The expression for the acoustic data is as follows: ; Optical data is used for feature alignment, and its expression is: ; The expression for the velocity data is: ; in, The data is acoustic observation data, and x is the state vector. For acoustic observation matrix, For optical observation data, For DVL observation data, For optical observation models, To observe the noise, It is the transpose of the rotation matrix.

[0102] Alternatively, the formula for calculating the residual Mahalanobis distance is:

[0103] in, For the first Modal residuals, For the first Modal residual covariance For the first The residual Mahalanobis distance of the modal residuals.

[0104] The updated formula for the quality factor is:

[0105] in, For the updated i-th quality factor, This is the i-th quality factor before the update. Forgetting factor, , ; c is the Mahalanobis distance scale.

[0106] Optionally, multi-source data fusion can be performed based on the weights of each modality (such as acoustic and optical modalities). For example, data related to the tool end position in acoustic and optical data can be fused according to the weights. The fusion result can then be used to calculate the parameters in the state vector. The weights are calculated using the following formula:

[0107] in, For the first Modal fusion weights, For the first Standard deviation of modal residuals.

[0108] Optionally, if the risk assessment module finds that the diagonal mean of the observed noise deviates from the actual residual variance for a long period of time (lasting for a certain period of time), the observed noise matrix is ​​automatically recalibrated with exponential smoothing to slowly track environmental statistics.

[0109] In one embodiment, it can be achieved by The method detects whether there is a deviation between the diagonal mean of the observed noise and the residual variance. Among other things, Let be the ratio of the residual variance of the i-th mode to the diagonal mean of the observation noise. For the first The observation noise matrix of the modality. . Observe the diagonal mean of the noise. If determined... The value exceeds the range (e.g., 0.5~2.0) for a duration longer than the predetermined time length. Then the observation noise matrix can be updated, and the update formula for the observation noise matrix can be: ,in, , To recalibrate the scaling factor, For exponential smoothing estimation, the residual variance is... The exponential smoothing estimate of the most recent residual variance can be calculated as follows:

[0110] In the formula The exponential smoothing coefficient (can be...) ), Let be the residual variance of the i-th mode. The residual variance of the i-th mode after smoothing estimation.

[0111] When optical data fails, the weights are shifted to acoustic and inertial data, while the acoustic positioning smoothing window is appropriately extended (by reducing the quality factor of the optical mode, the weights of acoustic / inertial data are relatively increased). To extend (to reduce transitions). In acoustic blockage (i.e., acoustic quality degradation (such as acoustic signal-to-noise ratio)). Reduced residual Mahalanobis distance When the limit is continuously exceeded, the pose of the tool end is maintained only by optical + inertial for a short period of time, and the drift upper limit monitoring is started (an upper limit is set for the pure optical / inertial maintenance segment, and if the limit is exceeded, wait for acoustic recovery or degradation processing) to prevent pose divergence.

[0112] If consecutive abnormal triggers occur, the abnormal trigger data storage and update module will be recorded for offline retraining to replace the base probability model or improve the sensitivity of residual judgment (e.g., based on the recorded data on risk probability). Medium weighting coefficient and , (Retraining / fine-tuning is performed after reaching a threshold). The pose, position, and reliability metrics of the fused output are analyzed. It is used not only for control and scheduling, but also as one of the variables for risk assessment.

[0113] In one embodiment, the condition for triggering the exception can be: consecutive occurrences And the number of times it appears If so, the mode is marked as "degenerate", and the mode is forced to... , ( );in, This is the threshold for triggering abnormal events. The threshold value is the residual Mahalanobis distance.

[0114] Optionally, credibility metrics can be integrated. The calculation formula can be: ,in, It is an inverse measure of the position covariance volume, used for state machine interlocking. This is the inverse quantization of position uncertainty.

[0115] Optionally, after preprocessing the monitoring data, multimodal fusion of acoustic data, optical data, and IMU / MRU data can be performed. Specifically, extended Kalman filtering (EKF) can be used to predict and update acoustic, optical, and inertial data with different frequencies and covariances. A quality factor is then constructed based on the modal residuals, variance consistency, and update frequency. Further generate weights Adaptive suppression of degenerate modes.

[0116] Optionally, the system also includes a data storage and update module. The data storage and update module is used to record the execution data of the execution module, as well as the action information and alarm information of emergency release and / or reentry. It performs trend analysis and data updates based on the execution data, action information, and alarm information. The data updates include updating the parameters corresponding to the dynamic trigger threshold and the early warning threshold.

[0117] Alternatively, the short window slope / spectrum can be correlated with autoregression ( Data is updated using predictive methods.

[0118] Optionally, coarse alignment can be performed based on acoustic data, optical data, and a dominant strategy. In the coarse alignment stage, acoustic data is used to obtain absolute position estimates and covariance of the tool tip and reference point. The IMU / MRU performs inertial propagation interpolation within the low-frequency acoustic interval. The DP (Dynamic Positioning System) controls and maintains the offset within the preparatory window. The guidance module (for the tool tip, performing attitude and lateral corrections) coarsely adjusts the axis angle of the workover tool. Specifically, the absolute position observation data of the tool tip and reference point are obtained using acoustic data. covariance , ; To account for observation noise, the inertial prediction results of the state vector and state covariance based on the observed value and covariance are as follows:

[0119]

[0120] Update the Kalman gain and state vector based on the inertial prediction results:

[0121]

[0122] In the formula, For state vectors, Let k be the predicted state vector at time k. Let k be the predicted state covariance. Let k be the state covariance at time k-1. This is the state transition function. Let Jacobi be the state at time k-1. for The transpose of the matrix, Let k be the process noise covariance at time k-1. For acoustic observation matrix, For acoustic observation covariance, For Kalman gain, The process noise at time k-1 is used. The position and attitude of the tool tip and reference point are determined based on the updated state vector, and coarse alignment is performed based on this position and attitude.

[0123] And obtain the lateral position error (this error is the plane error of the tool tip relative to the wellhead reference point), and control this error within the error conditions, which can be: ,in, The coarse alignment threshold can be 0.6~1.0m. This is the lateral position error. , The planar position of the tool end. The planar position is used as the reference point. After obtaining the updated values ​​of the state vector and Kalman gain, and the lateral position error, the rotation matrix is ​​obtained. (Generated from quaternion q), IMU acceleration measurement value Accelerometer bias value Gravitational acceleration vector g, fusion operation period Perform a rough alignment between the tool end and the reference point.

[0124] Optionally, the alignment condition includes that the deviation of the tool tip in the underwater workover tool is not greater than a predetermined threshold, and the deviation includes planar position error and angular error; the formula for calculating the deviation is:

[0125]

[0126] In the formula, For planar position error, For angular error, The planar position of the tool end, ( () is the plane position of the reference point. , , These are the weighting coefficients. The roll angle error at the tool end. This refers to the pitch angle error at the tool end. This refers to the yaw angle error at the tool end. Alignment conditions may include... ( (0.15~0.25 m) and ( (2~3°), once the alignment conditions are met, the alignment is considered complete. If the alignment conditions are not met, the position of the tool end can be iteratively adjusted (measurement-calculation). The position of the tool end is fine-tuned based on the calculation results until the alignment conditions are met.

[0127] Simultaneously, it can monitor whether the fusion confidence level is stable; if unstable, the observation weighted smoothing is extended; once the target is met, "alignment ready" is recorded. Specifically, if the fusion confidence interval... The corresponding main diagonal element is below the threshold (e.g.) If the confidence interval is unstable (e.g., the number of times the residual Mahalanobis distance is consecutively greater than the residual Mahalanobis distance threshold), then set the "Alignment Ready" flag. Exceeding the limit ,Right now If this is the case, then delayed interpolation and reduced weighting of the optical data will occur. The relevant expression can be: . This is the optical weight attenuation coefficient. The quality factor of the weighted optical data. This is the quality factor of the optical data before weighting.

[0128] Optionally, the underwater workover tool is controlled to move according to the reentry command, including: controlling the tool end to lock with the underwater wellhead based on the staged velocity curve, and acquiring the force information of the tool end during the locking process, and adjusting the locking according to the force information, the force information including lateral force and axial insertion force; The expression for the graded velocity curve is:

[0129] In the formula, Let s be the axial velocity corresponding to the insertion depth of the tool end, and s be the insertion depth. As the segment boundary, This represents the maximum insertion speed.

[0130] Optionally, the force sensor used to detect force information outputs a lateral force. If confirmed If the force threshold is reached, the insertion process is paused (and held). It then executes attitude correction commands to adjust the attitude of the tool end. The calculation formula used for adjustment can be: . Incremental control for attitude correction. For attitude error gain, This is the composite amount of angular deviation (i.e., angular error).

[0131] Optionally, at the end of the connection (e.g.) This allows for the use of a damping mode for heave compensation. Specifically, in the final stage, the control module calculates the damping control output. The damping control output and the heave feedforward component are then used to... (t) Superposition, and the heave compensation control output is obtained based on the superposition result. And control the heave compensation output to meet the requirements. .in, , Relative rise and fall; For coefficients, Limit the output for heave compensation control.

[0132] Optionally, after the insertion is completed, a seal integrity test is performed (to test the seal integrity between the tool section and the wellhead connection interface). This can be done by injecting test fluid to establish a test pressure curve, and by combining the compression stroke of the sealing ring (located at the sealing groove at the tool end and wellhead connection interface) with the leakage rate (linear leakage rate). Used to determine whether the condition is met. , If the upper limit of the leakage rate is not met, it is determined to be unqualified. If it fails, the insertion depth and insertion speed are adjusted locally.

[0133] In one embodiment, the test pressure curve can be:

[0134] in, This is the initial compensation item. The permeation / compression time constant. For linear leakage rate, Test stress for the target. Let be the test pressure at time t. The pass / fail criteria are determined based on curve fitting, and can be: ,in, Leakage rate limit The end time of the test. The permissible deviation for the target test pressure.

[0135] If it is determined to be unqualified, the tool tip can be controlled to make a slight retraction distance. , It can be 1~3 mm. Retry insertion (maximum number of attempts). Second-rate).

[0136] Optionally, after the seal integrity test is completed, functional connectivity verification is performed. This involves sending opening and closing commands to the subsea wellhead control channel (connected to the wellhead tree / valve assembly via an umbilical cable) to test response delay and pressure / flow changes (referring to pressure and flow response changes in the control channel), checking communication and power supply stability. If successful, the status is changed from "re-entering" back to "normal," and the risk model statistics window is reset to avoid historical deviations affecting the new work cycle. If it fails, the tool-end locking process is repeated. The entire re-entry process has multiple backtracking paths (…). Figure 3 (The backtrack path is indicated by a dashed line) and anomaly detection are used to improve the success rate and reduce the cost of repeated loops.

[0137] In one embodiment, valve open / close cycle commands can be issued M times (the specific number can be determined according to actual needs), and the response delay of the commands can be recorded. With pressure step amplitude The criteria for checking the stability of communication and power supply are as follows:

[0138]

[0139] In the formula, The response delay for the i-th instruction, For maximum response latency, The pressure step amplitude corresponding to the i-th instruction. This represents the minimum pressure step amplitude.

[0140] If the judgment criteria are met, the status will be changed to "normal", and the risk model statistics window will be reset (such as resetting the historical mean and clearing the variance to zero to prevent deviation).

[0141] Optionally, such as Figure 6 As shown, the execution module uses a state machine logic control mechanism to manage critical states such as normal, early warning, preparatory action, release, isolation, evacuation, and reentry. This mechanism is activated when the risk probability p exceeds the early warning probability. When the rate of change of tension increases significantly, an early warning state is activated.

[0142] The preparatory action state requires the risk probability to reach or exceed the dynamic trigger probability. Furthermore, the portfolio risk indicator R exceeds the indicator threshold. To avoid triggering by a single noise source. The interlocking before the release state includes well control linkage module preparation, communication health, and structural safety.

[0143] If the release is successful, the logic control mechanism immediately drives the linkage module to seal the wellhead and quickly transition to evacuation. After sea conditions recover, the reentry process is initiated, and the system returns to normal after functional verification. The emergency path allows for direct jump to release if extreme tension or abnormal offset occurs during the early warning state; the failure path allows for retraction to the preparatory action before release is completed, for reconfirmation or transfer to redundant mechanisms. All state transitions require a certain duration of anti-jitter conditions and record transition logs for later traceability and model fine-tuning. The state machine also schedules heave compensation parameter modes (including normal / feedforward enhancement / terminal damping modes) and suspends non-critical self-learning operations to avoid resource contention when emergency release priority occurs.

[0144] In one embodiment, the set of states managed by the state machine is:

[0145] The core transition condition for state transition is: Normal → Warning: The duration for which this condition is met , This is the warning threshold for the rate of change of tension.

[0146] Warning → Preparatory Actions: The duration for which this condition is met , Set a value for the duration.

[0147] Preparatory action → Release: All conditions in the interlocked condition set are met.

[0148] Release → Separation: The hydraulic main circuit or redundant mechanism has been successfully released, and the success flag is set.

[0149] Packer → Withdrawal: Packer closure pressure verification passed.

[0150] Evacuation → Reentry: Environmental indicators improve (effective wave height and communication health meet preset requirements).

[0151] Re-entry in progress → Normal: Functional connectivity verification passed.

[0152] Any state → Release (Emergency Branch): , For tension limit, This is the offset limit. This method is used to determine whether the set extreme value has been exceeded. If it has been exceeded, an emergency release operation is performed.

[0153] Optionally, the transition condition from any state to liberation must satisfy... .in, This represents the total number of decisions / sampling points within a fixed time window. Within the same time window, the number of times the "conversion condition" is met / the number of sampling points. To determine the success rate, it can be set at 85%.

[0154] Optionally, in the state machine, the priorities of each state are: Emergency Release > Isolation > Evacuation > Reentry > Warning / Preparatory Action > Data Retraining. When an emergency priority occurs, unnecessary calculations (such as online noise recalibration) are paused.

[0155] Optionally, the log records of the data storage and update module can be: ; in, These are the states of the state machine. This represents the risk probability and the average of the portfolio risk indicators corresponding to the time window. This is the set of weights for each modality. This is an interlock / exception flag; the log entry can be stored in a circular buffer and persisted.

[0156] Optionally, for training the data, a set of record features can be generated based on the system's working data. for: ; Use this set of recorded features as training samples and label them (release event = 1, non-release = 0). Train the model using the labeled samples, and update the logistic regression model or replace it with a time series model based on the training results. It is necessary to ensure that the AUC (Area Under Curve) of the new model is improved. (e.g., 0.02) and the false positive rate does not increase. Model switching uses a "shadow run" verification window. (For example, a work cycle), switch according to the verification results.

[0157] The underwater well workover system provided in this application includes: a monitoring module for collecting monitoring data at the work site and preprocessing the monitoring data, which includes environmental data, operational data, and sea state data; a risk assessment module for calculating current risk assessment information based on the preprocessed monitoring data; a control module for generating emergency release or re-entry commands based on the risk assessment information; and an execution module for receiving emergency release or re-entry commands and controlling the underwater well workover tool's actions according to the commands to protect the tool. This application's embodiment automatically collects operation-related monitoring data, performs risk assessments based on the data, and controls the underwater well workover tool's actions based on the assessment results. This effectively reduces reliance on personal experience, lowers the operational threshold, and offers fast response and high reliability, reducing the probability of equipment damage and significantly improving the safety and operational efficiency of underwater well workover tools in harsh sea conditions.

[0158] The terms "first," "second," "third," "fourth," "1," "2," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in a sequence other than that shown in the illustrations or text descriptions.

[0159] It should be understood that although arrows indicate various operation steps in the flowcharts of this application's embodiments, the order in which these steps are implemented is not limited to the order indicated by the arrows. Unless explicitly stated herein, in some implementation scenarios of this application's embodiments, the implementation steps in each flowchart can be executed in other orders as required. Furthermore, some or all steps in each flowchart, based on the actual implementation scenario, may include multiple sub-steps or multiple stages. Some or all of these sub-steps or stages can be executed at the same time, and each sub-step or stage can also be executed at different times. In scenarios where execution times differ, the execution order of these sub-steps or stages can be flexibly configured according to requirements, and this application's embodiments do not limit this.

[0160] The above description is only an optional implementation method for some implementation scenarios of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application without departing from the technical concept of this application also fall within the protection scope of the embodiments of this application.

Claims

1. A subsea well workover system, characterized in that, Connects to underwater well workover tools, including: The monitoring module is used to collect monitoring data at the work site and preprocess the monitoring data, which includes environmental data, work data, and sea state data. The risk assessment module is used to calculate the current risk assessment information based on the preprocessed monitoring data; The control module is used to generate an emergency release command or a re-entry command based on the risk assessment information. The execution module is used to receive the emergency release command or re-entry command and control the underwater well workover tool to operate according to the emergency release command or re-entry command in order to protect the underwater well workover tool.

2. The underwater well workover system according to claim 1, characterized in that, It also includes a data storage and update module, which is used to record the execution data of the execution module, as well as the emergency and / or re-entry action information and alarm information, and to perform trend analysis and data updates based on the execution data, action information and alarm information.

3. The underwater well workover system according to claim 1, characterized in that, Risk assessment information includes risk data and risk probability. The calculation of the risk probability includes: Based on the monitoring data, the risk data corresponding to the underwater well repair tool is calculated, and the risk data includes the predicted heave value, tension change rate, and offset change rate. The risk probability is calculated based on the risk data, and the formula for calculating the risk probability is: In the formula, For risk probability, , These are the weighting coefficients. For normalized tension, The rate of change of tension, It is the rate of change of offset; It is a predicted heave / sag value; It is the percentage of the effective field of view; It's the health of the communication. This is the sigmoid function.

4. The underwater well repair system according to claim 3, characterized in that, The underwater workover tool includes a release mechanism and a redundancy mechanism for connection to the underwater wellhead. The generation of the emergency release command includes: Based on the risk data, a combined risk index is calculated, and based on the combined risk index and the risk probability, the release mechanism and the redundant mechanism are controlled to perform preparatory actions. If the interlocking conditions are determined to be met based on the monitoring data and the risk data, an emergency unlocking command is generated to instruct the release mechanism to operate.

5. The underwater well workover system according to claim 4, characterized in that, Risk data includes dynamic trigger probabilities, and the formula for calculating the combined risk index is: In the formula, , , , , , These are the weighting coefficients; The preparatory actions performed by the release mechanism and the redundant mechanism based on the combined risk indicators and the risk probability control include: If it is determined that the combined risk index is greater than or equal to the index threshold and the risk probability is greater than or equal to the dynamic trigger threshold, then an instruction to perform a preparatory action is sent to the execution module.

6. The underwater well repair system according to claim 4, characterized in that, The subsea wellhead is equipped with a well control linkage module for sealing the subsea wellhead, which controls the action of the subsea workover tool according to the emergency release command, including: Control the release mechanism to disconnect the underwater workover tool from the underwater wellhead, and obtain the stroke information corresponding to the release mechanism; If a jam is determined based on the travel information, the redundant mechanism is used to disconnect the tool end of the underwater workover tool from the underwater wellhead, and the well control linkage module is controlled to close the underwater wellhead.

7. The underwater well workover system according to claim 4, characterized in that, The generation of the reentrancy instruction includes: The dominant strategy is determined based on the monitoring data. The position of the working end of the underwater workover tool is adjusted based on the acoustic data and optical data in the monitoring data and the dominant strategy. The dominant strategy includes an optical dominant strategy and an acoustic dominant strategy. If the alignment conditions are met based on the position, a reentry command is generated to instruct the tool end of the subsea workover tool to engage with the subsea wellhead.

8. The underwater well workover system according to claim 7, characterized in that, The step of determining the dominant strategy based on the monitoring data includes: The optical quality score and acoustic signal-to-noise ratio are calculated based on the monitoring data. The dominant strategy is determined based on the comparison results of the optical quality score and the quality score threshold, and the comparison results of the acoustic signal-to-noise ratio and the minimum acoustic signal-to-noise ratio threshold. The formula for calculating the optical quality score is: In the formula, To score the optical quality, The number of effective feature points, The desired number of feature points, Rate the contrast ratio. , These are weighting coefficients. + =1.

9. The underwater well workover system according to claim 7, characterized in that, The alignment condition includes that the deviation of the tool end in the underwater workover tool is not greater than a predetermined threshold, and the deviation includes planar position error and angular error; The formula for calculating the deviation is: In the formula, For planar position error, For angular error, The planar position of the tool end, ( () is the plane position of the reference point. , , These are the weighting coefficients. The roll angle error at the tool end. The pitch angle error at the tool end. This refers to the yaw angle error at the end of the tool.

10. The underwater well workover system according to claim 9, characterized in that, Controlling the underwater workover tool's movements according to the reentry command includes: The tool end is controlled to lock with the subsea wellhead based on the graded velocity curve, and the force information of the tool end is obtained during the locking process. The locking is adjusted according to the force information, which includes lateral force and axial insertion force. The expression for the graded velocity curve is: In the formula, The axial velocity corresponding to the insertion depth of the tool end is s, where s is the insertion depth. As the segment boundary, This represents the maximum insertion speed.

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