A wave compensator for a drilling platform

Abstract

The application discloses a wave compensation device for a drilling platform, which comprises a compensation execution mechanism, a multi-source sensing module, a control module and a hydraulic power station. The compensation execution mechanism is composed of a hydraulic driving unit and an electric driving unit in parallel. The hydraulic driving unit provides a low-frequency coarse adjustment compensation force, and the electric driving unit provides a high-frequency fine adjustment compensation force. The multi-source sensing module comprises an inertial measurement unit, a wave detection unit and a pressure sensor, which respectively acquire the platform posture, wave information and drill string load. The control module generates a composite control instruction through a model predictive control algorithm based on a wave feedforward signal, a posture feedback signal and a load signal. The hydraulic power station is connected with the hydraulic driving unit through a proportional oil supply pipeline, and a digital hydraulic valve group is arranged on the pipeline. The flow and pressure are adjusted according to the composite control instruction. The device combines electromechanical composite driving with predictive control, effectively solves the problems of response lag and high energy consumption of the traditional hydraulic system, and improves the compensation precision and system reliability.

Description

Technical Field

[0001] This invention relates to the field of deep-sea drilling technology, and in particular to a wave compensation device for drilling platforms. Background Technology

[0002] In deep-water drilling operations, hydraulic wave compensation devices are typically used to actively or passively compensate for the effects of six-degree-of-freedom motions (heave, sway, etc.) of the platform caused by ocean waves on the drill string and riser. Most existing compensation devices employ a purely hydraulic drive structure, using hydraulic cylinders as actuators and incorporating PID control algorithms. These cylinders extend and retract based on platform attitude data collected by an inertial measurement unit to counteract wave disturbances. Some improved designs incorporate wave radar as a feedforward sensor, attempting to enhance the compensation effect through a composite control system combining feedforward and feedback. Proportional valves or servo valves in the hydraulic system adjust flow rates according to control signals to output the compensating force.

[0003] However, in the complex environment of actual deep-sea operations, traditional pure hydraulic drive solutions are limited by the bulk modulus of the oil and the flow rate of the valve orifice. The system response has a millisecond-level delay, making it difficult to effectively suppress drill string vibration caused by high-frequency micro-amplitude waves. Moreover, continuous operation leads to a sharp rise in oil temperature, requiring a large cooling system and resulting in huge energy consumption. At the same time, the control strategy that relies solely on platform attitude feedback has obvious phase lag and cannot predict wave impact. Furthermore, the analog proportional valve of the hydraulic system is extremely sensitive to the cleanliness of the oil and is prone to jamming or leakage in the high-vibration, high-dust drilling platform environment, leading to compensation failure. In addition, fixed system parameters cannot adapt to changes in environmental pressure and drill string suspension weight at different water depths, which can easily create compensation dead zones or excessive rigidity, further reducing compensation accuracy and operational safety.

[0004] Therefore, in response to the urgent need for high-precision and high-reliability wave compensation in deep-water drilling, it is imperative to develop a new type of compensation device that integrates the advantages of high-power hydraulic drive and high-response electric drive, possesses multi-source information fusion and prediction capabilities, and has strong anti-pollution capabilities. By optimizing the actuator topology and control strategy, the device can fundamentally solve the problems of slow response, high energy consumption, and poor environmental adaptability of traditional hydraulic systems, thereby ensuring the continuity and safety of drilling operations in harsh sea conditions. Summary of the Invention

[0005] To improve existing methods and systems, a wave compensation device for drilling platforms is provided. This device generates composite control commands through a model predictive control algorithm. A hydraulic power station is connected to a hydraulic drive unit via a proportional oil supply pipeline. The pipeline is equipped with a digital hydraulic valve group, which adjusts the flow and pressure according to the composite control commands. This device effectively solves the problems of lag and high energy consumption in traditional hydraulic systems by combining electromechanical composite drive with predictive control, thereby improving compensation accuracy and system reliability.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This application provides a wave compensation device for drilling platforms, comprising: The compensation actuator includes a hydraulic drive unit and an electric drive unit. The hydraulic drive unit is used to provide low-frequency coarse adjustment compensation force, and the electric drive unit is connected in parallel with the hydraulic drive unit to provide high-frequency fine adjustment compensation force. The multi-source sensing module includes an inertial measurement unit for acquiring the platform's motion attitude, a wave detection unit for acquiring wave information, and a pressure sensor for acquiring the drill string load. The control module is connected to the multi-source sensing module and the compensation actuator. The control module is configured to generate composite control commands based on the feedforward signal of the wave detection unit, the feedback signal of the inertial measurement unit, and the load signal of the pressure sensor through a model predictive control algorithm. The hydraulic power unit is connected to the hydraulic drive unit via a proportional oil supply line. The proportional oil supply line is equipped with a digital hydraulic valve group, which adjusts the flow and pressure entering the hydraulic drive unit according to the composite control command.

[0007] In some embodiments, the electric drive unit is a linear motor or a voice coil motor, the stator portion of the electric drive unit is fixed to the drilling platform deck, and the mover portion of the electric drive unit is coaxially connected to the piston rod of the hydraulic drive unit via a spline or guide shaft. The linear motor's mover stroke is less than 10% of the hydraulic drive unit's stroke, and its response frequency is greater than 50Hz.

[0008] In some embodiments, the digital hydraulic valve group includes a preset number of high-speed switching solenoid valves, which operate in PWM pulse width modulation mode. The control module is configured to convert composite control commands into PWM duty cycle signals to drive the on / off switching of high-speed switching solenoid valves, thereby achieving digital quantitative control of the speed of the hydraulic drive unit.

[0009] In some embodiments, an adaptive accumulator assembly is also included, which is connected in parallel to the proportional fuel supply line; The adaptive accumulator assembly includes a main accumulator and an auxiliary cylinder. The auxiliary cylinder is connected to the nitrogen chamber of the main accumulator through an air passage, and a regulating valve is provided on the air passage. The control module adjusts the opening of the regulating valve based on the drill string suspension signal detected by the pressure sensor, so as to dynamically change the equivalent pre-charge pressure of the main accumulator.

[0010] In some embodiments, the specific execution logic of the control module is as follows: S1: Establish the transfer function model of wave disturbance and platform motion; S2: Based on the data from the wave detection unit, the data is input into the transfer function model to generate a predicted displacement curve; S3: Fuse the predicted displacement curve with the actual attitude data, and estimate the residual wave disturbance through the disturbance observer; S4: Distribute low-frequency components to the hydraulic drive unit and high-frequency components to the electric drive unit.

[0011] In some embodiments, the hydraulic drive unit includes a hydraulic cylinder and a piston rod, with a mechanical safety lock provided at the end of the piston rod; The mechanical safety lock is a power-off braking electromagnetic brake. When the control module detects a power failure, communication interruption, or vibration acceleration exceeding a preset threshold, the mechanical safety lock automatically locks the piston rod.

[0012] In some embodiments, the digital hydraulic valve assembly is integrally formed inside the valve block substrate using an additive manufacturing process to form an integrated flow channel; The integrated flow channel includes an oil inlet, an oil return port, a working oil port, and an oil drain port. The oil inlet, oil return port, working oil port, and oil drain port are directly connected to the high-speed switching solenoid valve through internal channels.

[0013] In some embodiments, the multi-source sensing module further includes a proximity switch disposed at the top of the drill string for detecting the lateral offset of the drill string; The control module is configured to limit the output power of the electric drive unit and adjust the center oil pressure of the hydraulic drive unit to provide radial normalizing force when the lateral offset exceeds the safety threshold.

[0014] In some embodiments, the hydraulic power unit includes a main pump, a motor, and a cooling circulation loop; The cooling circulation loop includes a plate heat exchanger and seawater cooling pipes. The control module adjusts the flow rate of the seawater cooling pipes based on the oil temperature sensor data to keep the hydraulic oil temperature within the range of 40℃-60℃.

[0015] In some embodiments, the device is installed between the traveling block and the hook, or between the top drive unit and the derrick. The axis of the compensation actuator coincides with the axis of the drill string.

[0016] This application employs a composite actuator combining hydraulic and electric drive units in parallel, integrating multi-source sensing modules and model predictive control algorithms to achieve precise flow regulation using digital hydraulic valve assemblies. This solution utilizes the electric drive unit for rapid response to high-frequency, low-amplitude waves, while the hydraulic unit handles low-frequency coarse-adjustment loads, effectively compensating for the shortcomings of traditional hydraulic systems such as lag and high energy consumption. The digital valve assemblies exhibit strong anti-contamination capabilities, significantly improving system reliability and compensation accuracy, ensuring the continuity and safety of drilling operations under harsh sea conditions. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the wave compensation device for drilling platforms proposed in this invention; Figure 2 The present invention provides a flowchart illustrating the specific execution logic of the control module.

[0018] In the diagram: 1. Compensation actuator; 11. Hydraulic drive unit; 12. Electric drive unit; 2. Multi-source sensing module; 21. Inertial measurement unit; 22. Wave detection unit; 23. Pressure sensor; 3. Control module; 4. Hydraulic power station; 41. Proportional oil supply line; 42. Digital hydraulic valve group. Detailed Implementation

[0019] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0020] This application provides a wave compensation device for drilling platforms, such as... Figure 1 As shown, it includes: The compensation actuator 1 includes a hydraulic drive unit 11 and an electric drive unit 12. The hydraulic drive unit 11 is used to provide low-frequency coarse adjustment compensation force, and the electric drive unit 12 is connected in parallel with the hydraulic drive unit 11 to provide high-frequency fine adjustment compensation force. The multi-source sensing module 2 includes an inertial measurement unit 21 for acquiring the platform's motion attitude, a wave detection unit 22 for acquiring wave information, and a pressure sensor 23 for acquiring the drill string load. Control module 3 is connected to multi-source sensing module 2 and compensation actuator 1 respectively. Control module 3 is configured to generate composite control commands based on the feedforward signal of wave detection unit 22, feedback signal of inertial measurement unit 21 and load signal of pressure sensor 23 through model predictive control algorithm. The hydraulic power station 4 is connected to the hydraulic drive unit 11 through the proportional oil supply line 41. The proportional oil supply line 41 is equipped with a digital hydraulic valve group 42, which adjusts the flow and pressure entering the hydraulic drive unit 11 according to the composite control command.

[0021] In practical implementation, this wave compensation device achieves high-precision compensation for deep-sea operations through a combined electromechanical-hydraulic control strategy. Taking the control logic of the actuator as an example, when the wave detection unit 22 (such as an X-band wave measuring radar) detects that the wave peak is about to arrive within the next 5 seconds, the control module 3 calculates the platform's heave trajectory in advance based on the model predictive control algorithm, and allocates the high-frequency micro-motion component (such as vibration with a frequency greater than 2Hz) to the electric drive unit 12 (such as a voice coil motor), which uses its millisecond-level response speed to directly drive the piston rod for fine adjustment. At the same time, the low-frequency coarse adjustment component (such as heave amplitude exceeding 0.5 meters) is allocated to the hydraulic drive unit 11, which adjusts the main oil circuit flow through the digital hydraulic valve group 42. This parallel topology allows the electric drive unit 12 to be dedicated to "fast-changing" disturbances, avoiding the throttling losses and oil temperature rise caused by frequent reversals in traditional hydraulic systems, while the hydraulic unit uses its high power density advantage to bear "slow-changing" loads such as drill string gravity. The two complement each other to achieve full-frequency coverage. Another concrete implementation technology lies in the realization of the digital hydraulic valve group 42. This valve group consists of multiple high-speed switching solenoid valve arrays integrated into a 3D-printed valve block. The control module 3 converts the composite control commands into PWM pulse width modulation signals, driving the solenoid valves to regulate the flow into the hydraulic cylinder in a high-frequency on / off manner. Compared with traditional proportional servo valves, this digital control method is insensitive to oil contamination, has strong anti-jamming ability, and can linearly increase the system throughput by increasing the number of parallel valves, adapting to the needs of drilling rigs of different tonnages. In addition, the pressure sensor 23 in the multi-source sensing module 2 monitors the changes in drill string suspension weight in real time. The control module 3 introduces a load torque observer. When it detects that the drill pressure suddenly decreases due to wave impact, the system automatically increases the preload of the hydraulic drive unit 11 to prevent drill string instability. This adaptive adjustment based on load feedback significantly improves the robustness of the system under extreme sea conditions.

[0022] The beneficial effects of the above technical solution are mainly reflected in the significant improvements in three dimensions: compensation accuracy, system energy consumption, and reliability. Firstly, by adopting a parallel composite drive mode of "electric high-frequency + hydraulic low-frequency," the electric drive unit 12 directly overcomes the limitations of hydraulic oil volume modulus and valve response delay, effectively eliminating the phase lag problem present in traditional hydraulic compensation at high frequencies. This significantly reduces the residual displacement error at the drill string end, solving the problems of drill bit skipping and well deviation control caused by micro-amplitude high-frequency vibrations in deep-water drilling. Secondly, the application of the digital hydraulic valve group 42 eliminates the system's reliance on high-precision analog proportional valves. The fully open and fully closed working characteristics of the high-speed switching valve reduce throttling heat generation. Combined with the electric drive unit 12 bearing the high-frequency load, this significantly reduces the overflow loss and cooling load of the hydraulic power station 4, resulting in lower overall energy consumption and meeting the energy conservation and emission reduction requirements of offshore platforms. Furthermore, the combination of multi-source sensing and model predictive control utilizes the feedforward information from the wave radar to compensate for the feedback delay of the inertial measurement unit 21. At the same time, the load signal from the pressure sensor 23 corrects the model parameters in real time, enabling the system to maintain a stable compensation output by relying on the load observer even when the wave radar signal is distorted due to rainstorm interference, thus avoiding malfunctions. The anti-contamination characteristics of the digital valve group and the non-contact or low-friction transmission of the electric drive unit 12 (depending on the specific motor type) significantly extend the maintenance cycle of core components and reduce the risk of downtime maintenance in harsh marine environments, thereby ensuring the continuity and safety of drilling operations.

[0023] In some embodiments, the electric drive unit 12 is a linear motor or a voice coil motor, the stator portion of the electric drive unit 12 is fixed to the drilling platform deck, and the mover portion of the electric drive unit 12 is coaxially connected to the piston rod of the hydraulic drive unit 11 via a spline or guide shaft. The linear motor's mover stroke is less than 10% of the stroke of the hydraulic drive unit 11, and its response frequency is greater than 50Hz.

[0024] In practical implementation, to achieve efficient output of high-frequency fine-tuning compensation force, the electric drive unit 12 adopts a high dynamic response linear motor or voice coil motor structure. Its stator is firmly fixed to the deck base of the drilling platform by a rigid bracket to ensure that it does not sway with the platform during operation, while the mover is coaxially rigidly connected to the piston rod of the hydraulic drive unit 11 through a precision spline pair or guide shaft. This mechanical connection method allows the thrust of the linear motor to act directly on the drill string suspension point without the need for intermediate transmission through hydraulic oil, thereby eliminating the elastic deformation caused by the compressibility of the oil. In actual assembly, considering that the hydraulic cylinder usually has a low-frequency coarse adjustment of several meters to cope with the platform's rise and fall, the stroke of the linear motor mover is strictly limited to within 10% of the hydraulic stroke. For example, when the hydraulic stroke is 2 meters, the linear motor stroke is only 150 millimeters. This short stroke design significantly reduces the mass of the motor mover. Combined with the optimized magnetic circuit design, its mechanical response frequency easily exceeds 50Hz, which can specifically compensate for high-frequency micro-amplitude vibrations caused by waves in real time. In terms of control implementation, when the wave detection radar in the multi-source sensing module 2 captures the upcoming wave peak signal, the control module 3 uses a model prediction algorithm to decompose the future disturbance and directly converts the drastically changing high-frequency components into current commands for the linear motor, driving the actuator to make a reverse micro-displacement within milliseconds. Meanwhile, the hydraulic drive unit 11 only needs to adjust slowly according to the low-frequency components. The parallel connection of the two at the physical level and the frequency domain division of labor at the control level constitute a highly efficient composite drive system.

[0025] The beneficial effects of this technical solution are mainly reflected in its fundamental overcoming of the defects of "inertial lag" and "high-frequency weakness" in traditional hydraulic systems. Because the linear motor or voice coil motor is directly connected to the piston rod and has an extremely short stroke, the inertia of its moving parts is much smaller than that of the massive piston assembly of the hydraulic cylinder. This gives the system a strong ability to follow high-frequency wave disturbances above 50Hz, enabling fine-tuning before the hydraulic valve group has completed flow regulation. This significantly reduces the residual vibration amplitude at the drill string end, solving the problems of drill bit wear and well deviation control caused by micro-vibrations in deep-sea drilling. Simultaneously, by offloading the high-frequency load to the electric drive unit 12, the hydraulic power station 4 no longer needs to maintain a high-pressure overflow state for high-frequency response. The digital hydraulic valve group 42 only needs to operate at a lower switching frequency to regulate the average flow. This not only significantly reduces the throttling heat and energy consumption of the hydraulic system but also reduces cavitation and wear at the valve ports caused by high-frequency commutation, extending the service life of core hydraulic components. In addition, the rigid connection of splines or guide shafts provides higher structural rigidity compared to flexible hinges, which allows the electric drive unit 12 to provide compensation force while also playing an auxiliary role in straightening, preventing the drill string from shifting too much under lateral surges. This compact electromechanical design achieves a dual improvement in compensation accuracy and system reliability without significantly increasing the size and weight of the equipment.

[0026] In some embodiments, the digital hydraulic valve group 42 includes a preset number of high-speed switching solenoid valves, which operate in PWM pulse width modulation mode. The control module 3 is configured to convert composite control commands into PWM duty cycle signals to drive the on / off switching of high-speed switching solenoid valves, thereby achieving digital quantitative control of the speed of the hydraulic drive unit 11.

[0027] In practical implementation, the digital hydraulic valve group 42 is mainly achieved through the array integration of high-speed switching solenoid valves and pulse width modulation control. For example, in terms of the physical structure of the valve group, additive manufacturing technology is used to directly 3D print and embed multiple high-speed switching solenoid valves into the valve block matrix, eliminating traditional pipeline connections and forming an integrated flow channel. This structure not only significantly reduces the number of pipe joints to reduce the risk of high-pressure oil leakage, but also shortens the flow path of oil in the valve body, improving the response speed. In terms of control logic, after the control module 3 generates a composite control command, it will convert it into a PWM duty cycle signal of a specific frequency. For example, when the hydraulic drive unit 11 needs to extend at a medium speed, the control module 3 outputs a pulse signal with a duty cycle of 60%, driving the high-speed switching solenoid valve to remain open for 60% of the time and closed for 40% of the time per unit time. By utilizing the inertial effect of the oil, a continuous average thrust is formed in the hydraulic cylinder, thereby replacing the linear adjustment function of the traditional proportional valve. Another specific implementation example is the redundant control design, which uses multiple small-diameter high-speed switching solenoid valves in parallel to be equivalent to a large-flow main valve. When a solenoid valve experiences a coil open circuit or jamming failure, the control module 3 can recalculate the PWM distribution strategy through the remaining effective valves to maintain the basic operation of the hydraulic drive unit 11. This flexibility of digital control is difficult to achieve in traditional analog hydraulic systems.

[0028] The beneficial effects of this technical solution mainly stem from the replacement of analog control by digital control and the structural advantages brought by integration. Firstly, since the high-speed switching solenoid valve only operates in two states—fully open or fully closed—it completely avoids the nonlinear region where traditional proportional or servo valves are extremely sensitive to small openings. This eliminates the huge pressure loss and heat generation caused by valve throttling, significantly reducing the energy consumption and cooling load of the hydraulic power station 4. Secondly, PWM duty cycle control is essentially a digital quantization adjustment; its control accuracy depends only on the clock frequency, not the machining accuracy of the valve core. This makes the speed control of the hydraulic drive unit 11 more linear and has high repeatability, effectively solving the drift problem caused by oil temperature changes in traditional hydraulic systems. Furthermore, the integrated 3D-printed valve block eliminates a large number of threaded connection points. In the high-frequency vibration environment of the drilling platform, this tubeless design greatly improves fatigue resistance and reduces the risk of external leakage due to vibration loosening. In addition, high-speed switching valves have a much higher tolerance for oil contamination than precision proportional valves because their flow area is large when fully open, making it less likely for contaminants to cause blockages. This directly reduces the requirements for maintenance of marine hydraulic oil and improves the overall reliability and uptime of the system.

[0029] In some embodiments, an adaptive accumulator assembly is also included, which is connected in parallel to the proportional oil supply line 41. The adaptive accumulator assembly includes a main accumulator and an auxiliary cylinder. The auxiliary cylinder is connected to the nitrogen chamber of the main accumulator through an air passage, and a regulating valve is provided on the air passage. The control module 3 adjusts the opening of the regulating valve based on the drill string suspension signal detected by the pressure sensor 23, so as to dynamically change the equivalent pre-charge pressure of the main accumulator.

[0030] In practical implementation, the adaptive accumulator assembly is mainly deployed through a gas-hydraulic linkage and real-time pressure regulation mechanism to achieve dynamic optimization of system stiffness. For example, in terms of mechanical structure, the main accumulator adopts a bladder-type structure and is connected in parallel to the main oil supply pipeline of the hydraulic power station 4. The auxiliary cylinder is connected to the nitrogen chamber of the bladder through a stainless steel air circuit. The high-speed proportional regulating valve installed on the air circuit is driven by the current signal of the control module 3. When the pressure sensor 23 detects a drastic change in the drill string suspension due to wave rise and fall, such as a sudden reduction in drill string suspension indicating that the platform is in the peak rising phase, the control module 3 will immediately calculate the optimal pre-charge pressure required under the current working condition and output a corresponding current signal to open the regulating valve, so that the auxiliary cylinder can replenish high-pressure gas to the nitrogen chamber, thereby increasing the equivalent pre-charge pressure of the main accumulator and avoiding compensation lag due to insufficient system pressure. Another specific implementation method uses a differential cylinder as an auxiliary cylinder, utilizing its large and small cavity area ratio to achieve nonlinear pressure gain regulation. This allows for fine-tuning when the drill string weight changes slightly, while providing rapid, wide-range pressure compensation during sudden weight changes. This design transforms the accumulator from a fixed-parameter spring into an elastic element that "breathes" with the drill string weight. Furthermore, to prevent pressure runaway due to valve jamming, a mechanical safety relief valve is connected in parallel in the air circuit. This ensures that the maximum pressure is physically limited in the event of electronic control failure, guaranteeing system safety.

[0031] The main benefits of this technical solution lie in solving the "dead zone" problem of traditional fixed pre-charge pressure accumulators being unable to adapt to varying working conditions and optimizing system energy consumption. Firstly, since the suspended weight of the drill string changes in real time with drilling depth and wave disturbances during operation, traditional accumulators, if set with the maximum suspended weight as the pre-charge pressure, will be unable to absorb high-frequency micro-fluctuations under light loads due to excessive system rigidity; if set with the average suspended weight, the compensation force will be insufficient under heavy loads. By introducing auxiliary cylinders and regulating valves, the control module 3 can correct the pre-charge pressure in real time based on the drill string suspended weight signal, ensuring that the accumulator's oil suction and discharge characteristics always match the current load, thus providing smooth compensation force under all working conditions and significantly improving compensation accuracy. Secondly, the dynamic pre-charge pressure mechanism reduces the overflow loss of the hydraulic pump. When wave disturbances are small, the system does not need to maintain high pressure standby; the accumulator can meet the fine-tuning requirements at a lower pre-charge pressure. This reduces the average working pressure of the hydraulic power station 4, thereby reducing the pump's drive torque and heat generation, and extending the service life of the hydraulic oil and seals. Furthermore, this adaptive structure enhances the system's shock resistance. When the drill string suddenly encounters resistance or releases drilling pressure, the auxiliary cylinder can quickly adjust the air chamber volume like a shock absorber to absorb hydraulic shock peaks, prevent pipeline rupture or actuator creep, and ensure the continuity and safety of deepwater drilling operations under extreme sea conditions.

[0032] In some embodiments, such as Figure 2As shown, the specific execution logic of control module 3 is as follows: S1: Establish the transfer function model of wave disturbance and platform motion; S2: Based on the data from wave detection unit 22, the data is input into the transfer function model to generate a predicted displacement curve; S3: Fuse the predicted displacement curve with the actual attitude data, and estimate the residual wave disturbance through the disturbance observer; S4: Distribute the low-frequency component to the hydraulic drive unit 11 and the high-frequency component to the electric drive unit 12.

[0033] In practical implementation, the execution logic of control module 3 achieves precise decoupling and allocation of wave disturbances through a multi-layered cascaded algorithm architecture. First, when establishing the transfer function model of wave disturbances and platform motion, a system identification method is used. Historical sea state data and platform motion response are used to train a mathematical model containing second-order oscillation elements and damping characteristics. This model can characterize the dynamic relationship between platform heave and wave excitation under different wave directions and frequencies. When the wave detection unit 22 (such as an X-band radar) acquires real-time wave height and direction data, it directly substitutes these as input variables into the transfer function model. Convolution operations are then used to generate a predicted platform displacement curve for the next few seconds, giving the system "look-ahead" capability. Second, to correct model errors and environmental noise, control module 3 introduces a Kalman filter as an interference observer. Residual analysis is performed between the radar-generated predicted displacement and the actual acceleration and velocity data fed back by the inertial measurement unit 21. This allows for real-time estimation of the residual wave disturbances not captured by the model, effectively filtering out clutter interference from the radar in rainy or foggy weather. Finally, based on the wavelet packet transform algorithm, the fused total disturbance signal is decomposed in the frequency domain. A specific cutoff frequency (such as 2Hz) is set, and the low-frequency high-energy components are directly converted into displacement commands of the hydraulic drive unit 11, while the high-frequency micro-amplitude components are allocated to the electric drive unit 12, thus realizing the physical hierarchical control of the actuator.

[0034] The beneficial effects of this control strategy are mainly reflected in the qualitative leap in compensation accuracy and the significant reduction in system energy consumption. Due to the introduction of feedforward prediction based on the transfer function model (S1-S2), the system no longer relies solely on lagging attitude feedback but can anticipate wave impact actions, fundamentally eliminating the phase lag caused by system inertia in traditional PID control. This allows the drill string to more accurately "float" above the seabed wellhead. The introduction of the disturbance observer (S3) endows the system with extremely strong robustness. Even in the event of a brief loss or distortion of the wave radar signal, the actual data from the inertial unit can still be used to estimate the true disturbance through the observer, avoiding miscompensation caused by feedforward errors and ensuring operational safety. The frequency domain allocation strategy (S4) is the key to achieving high efficiency. It fully utilizes the high power density of the hydraulic drive unit 11 to process low-frequency energy, while leveraging the fast high-frequency response of the electric drive unit 12 to process micro-amplitude vibrations. This "each doing its own job" control method avoids the hydraulic system from frequently throttling to respond to high-frequency signals, significantly reducing valve pressure loss and oil heating. It also prevents the electric drive unit 12 from saturating due to stroke overload. Thus, while ensuring high-precision compensation, it significantly reduces the load rate and overall energy consumption of the hydraulic power station 4.

[0035] In some embodiments, the hydraulic drive unit 11 includes a hydraulic cylinder and a piston rod, and a mechanical safety lock is provided at the end of the piston rod; The mechanical safety lock is a power-off braking electromagnetic brake. When the control module 3 detects a power failure, communication interruption, or vibration acceleration exceeding a preset threshold, the mechanical safety lock automatically locks the piston rod.

[0036] In practical implementation, the mechanical safety lock is primarily activated through a power-off braking structure that combines pure mechanical and electromagnetic components. For example, a normally closed electromagnetic brake is installed at the end flange of the hydraulic cylinder piston rod. Its brake shoes are made of a sintered material with a high coefficient of friction. Under normal conditions, they tightly grip the outer surface of the piston rod under the action of a strong disc spring. When the system is powered normally, the control module 3 supplies a continuous current to the brake coil, and the resulting electromagnetic force overcomes the spring preload, causing the brake shoes to release and allowing the piston rod to extend and retract freely. Once the system loses power due to a fault or communication link interruption, the coil's magnetic force disappears instantly, and the disc spring resets within milliseconds, pushing the brake shoes to clamp the piston rod again. Another specific implementation involves directly integrating an acceleration sensor onto the outer wall of the hydraulic cylinder. When the vibration acceleration detected by the sensor exceeds a preset safety threshold (e.g., 10 m / s² representing extreme sea conditions or equipment collisions), the sensor... 2The control module 3 directly cuts off the power supply circuit to the brake coil, forcibly triggering mechanical locking. This design allows the safety lock to not only cope with electrical faults but also actively defend against severe physical impacts. In addition, to ensure effective locking even when the hydraulic circuit ruptures or the pressure drops to zero, the mechanical structure of the brake is designed as a pure friction self-locking type, which does not rely on any hydraulic pressure assistance and can maintain the locked state solely by spring force and friction.

[0037] The beneficial effects of this technical solution are mainly reflected in the enhanced inherent safety and equipment protection capabilities under extreme operating conditions. Firstly, due to the adoption of a "fail-safe" logic of power-off braking, in the event of sudden situations such as platform power grid fluctuations or control system failure, the mechanical safety lock automatically engages, transferring the weight of the drill string directly to the rigid mechanical structure via the piston rod. This prevents the drill string from falling or violently swinging due to loss of support after a power outage, as is common with traditional hydraulic compensation devices, thus preventing collisions between the drill string and the wellhead, or even blowouts. Secondly, the introduction of vibration acceleration as a trigger condition endows the system with predictive protection capabilities. When the wave impact force is too large, causing the hydraulic system to be about to overload, the mechanical lock intervenes in advance, limiting the piston rod's ultimate displacement. This prevents damage to the hydraulic cylinder due to overtravel or destruction of seals by high pressure, significantly extending the service life of the core actuator. Furthermore, this purely mechanical locking method does not rely on hydraulic oil pressure, thus solving the hidden danger of locking failure caused by pipeline leakage in traditional hydraulic locks. In the low temperature and high pressure environment of the deep sea, its reliability is far higher than that of hydraulic control check valves, providing the last indestructible physical defense for drilling operations and significantly reducing the operational risks and equipment maintenance costs under harsh sea conditions.

[0038] In some embodiments, the digital hydraulic valve assembly 42 is integrally formed inside the valve block substrate using an additive manufacturing process to form an integrated flow channel; The integrated flow channel includes an oil inlet, an oil return port, a working oil port, and an oil drain port. The oil inlet, oil return port, working oil port, and oil drain port are directly connected to the high-speed switching solenoid valve through internal channels.

[0039] In practical implementation, the integrated molding of the digital hydraulic valve group 42 is mainly achieved through the direct construction of complex internal flow channels using metal additive manufacturing technology. For example, selective laser melting (SLM) is used with high-strength alloy steel as raw material to print the valve block substrate and the internal integrated flow channels in one go. This eliminates the need for deep hole drilling, cartridge valve mounting holes, and external connecting pipelines required by traditional valve blocks. The high-speed switching solenoid valve is directly embedded in the printed cavity, and its oil port is directly connected to the main oil inlet, oil return port, working oil port, and oil drain port through the internally designed three-dimensional curved flow channel. This design changes the flow path of the oil inside the valve group from the traditional "S"-shaped bend to a smooth streamline, significantly reducing pressure loss along the flow path. Another concrete application of this technology lies in the integrated design of multi-way valves. Utilizing the stacking advantages of 3D printing, multiple high-speed switching solenoid valves are arranged vertically or horizontally within the same valve block. Oil distribution and merging are achieved through internally printed flow channels, forming a multi-valve assembly. This structure compresses the traditional hydraulic piping system, which originally required several cubic meters of space, into a compact metal block, directly installed near the hydraulic cylinder, significantly shortening the length of the hydraulic lines. Furthermore, in terms of the inner wall treatment of the flow channels, electrochemical polishing can be performed after additive manufacturing to reduce surface roughness and decrease oil flow resistance. Simultaneously, damping orifices or buffer grooves are designed in the critical valve port transition areas to suppress hydraulic shocks caused by high-speed switching.

[0040] The beneficial effects of this technical solution are mainly reflected in the significant improvement of system reliability, dynamic response, and energy efficiency. Firstly, by eliminating a large number of external pipes and fittings, the leakage points of high-pressure oil are greatly reduced. In the high-frequency vibration environment of deep-sea drilling platforms, this pipe-free integrated structure avoids the risk of external leakage due to loose threads or fatigue fracture, significantly improving the inherent safety of the hydraulic system. Secondly, the streamlined design of the internal integrated flow channel reduces local resistance and turbulence of the oil, not only reducing the driving load of the hydraulic pump but also reducing the heat generated by throttling, thereby reducing the requirements of the cooling system and improving the system's energy utilization efficiency. Furthermore, the direct connection between the high-speed switching solenoid valve and the oil port eliminates the volumetric effect of intermediate pipes, shortening the valve group's response time from the traditional hundreds of milliseconds to the millisecond level. Combined with model predictive control algorithms, it can more accurately execute composite control commands, achieving high-frequency and precise adjustment of the hydraulic drive unit 11. In addition, the integrated structure of additive manufacturing has extremely high overall rigidity, which can withstand the severe impact and vibration during drilling operations, and prevents the control failure caused by loose connecting bolts in traditional split valve groups, thus ensuring the continuous and stable operation of the wave compensation device under harsh working conditions.

[0041] In some embodiments, the multi-source sensing module 2 further includes a proximity switch disposed on the top of the drill string for detecting the lateral offset of the drill string; The control module 3 is configured to limit the output power of the electric drive unit 12 and adjust the center oil pressure of the hydraulic drive unit 11 to provide radial straightening force when the lateral offset exceeds the safety threshold.

[0042] In practical implementation, the lateral displacement monitoring technology at the top of the drill string is mainly achieved through the combination of non-contact sensors and differential control of hydraulic cylinders. For example, the proximity switch uses a high-frequency eddy current sensor, arranged in pairs in the orthogonal direction of the guide frame at the top of the drill string, to monitor the relative distance between the outer wall of the drill string and the center of the wellhead in real time. When the drill string swings laterally due to a surge, causing the gap to be less than the safety threshold, the sensor outputs a high-level signal to the control module 3. After receiving the signal, the control module 3 first limits the inverter output current of the electric drive unit 12, forcibly limiting its thrust within a safe range, preventing the electric drive unit 12 from continuing to perform high-frequency fine-tuning when the drill string has already shifted significantly, thus increasing the risk of collision. At the same time, the control module 3 sends a specific command to the digital hydraulic valve group 42 to adjust the oil pressure ratio entering the rodless chamber and the rod chamber of the hydraulic drive unit 11, so that the piston rod, while maintaining axial compensation force, uses the radial component force generated by the pressure difference on both sides to push the drill string back to center. Another specific implementation method is to adopt a double-rod hydraulic cylinder structure. By independently controlling the pressure of the oil circuits on both sides, an asymmetrical hydraulic support force is actively established when the drill string deviates laterally, forming a straightening effect similar to an "active bearing". This structure transforms the traditional passive constraint into active correction.

[0043] The main benefits of this technical solution are improved drill string stability and enhanced downhole operational safety. Due to the extremely long drill string in deep-sea drilling, resembling a slender rod, it is highly susceptible to buckling instability under wave forces. Traditional attitude compensation only focuses on vertical heave, neglecting the cumulative effect of lateral displacement. By introducing a proximity switch to monitor lateral offset, the system obtains complete information on the drill string's spatial position. When the offset approaches the wellbore friction limit, limiting the power of the electric drive unit 12 avoids erroneous excitation, preventing the drill string from colliding with the blowout preventer or wellbore. Simultaneously, utilizing the high thrust of the hydraulic drive unit 11 provides radial normalizing force, effectively adding an intelligent guiding device to the top of the drill string. This significantly increases the critical instability load of the drill string, ensuring stable drilling pressure even in harsh sea conditions and preventing drill bit trajectory deviation or wellbore instability accidents caused by severe drill string oscillation. Furthermore, this state-switching-based control strategy optimizes energy distribution, enabling the electric drive unit to operate efficiently under non-hazardous conditions and the hydraulic unit to take over the uprighting task under hazardous conditions, thus achieving a balance between safety and efficiency.

[0044] In some embodiments, the hydraulic power unit 4 includes a main pump, a motor, and a cooling circulation loop; The cooling circulation loop includes a plate heat exchanger and seawater cooling pipes. The control module 3 adjusts the flow rate of the seawater cooling pipes according to the oil temperature sensor data to keep the hydraulic oil temperature within the range of 40℃-60℃.

[0045] In practical implementation, the thermal management of the hydraulic power station 4 achieves precise and stable oil temperature through closed-loop temperature control and corrosion-resistant heat exchange technology. For example, an electric proportional regulating valve driven by the control module 3 is installed on the seawater cooling pipeline. This valve automatically adjusts the valve opening to change the seawater flow rate based on real-time data fed back by the platinum resistance thermometer immersed in the oil tank. When the oil temperature rises to the upper limit of 60°C due to high-frequency compensation, the valve is fully opened to introduce the maximum flow of low-temperature seawater, while the flow rate is reduced during the low-temperature start-up phase to avoid excessively low oil temperature. Another specific implementation technology is the material selection and structural design of the plate heat exchanger. Titanium alloy corrugated plates are used to resist the strong corrosion of seawater, and the number of gaskets is reduced through brazing, improving pressure resistance and heat exchange efficiency. At the same time, the heat exchanger is integrated into the main channel of the power station's return oil pipeline, utilizing the turbulence effect of the return oil to enhance heat exchange. In addition, a variable frequency seawater pump can be introduced into the cooling circulation loop. With the PID adjustment algorithm of control module 3, the pump speed can be corrected in real time according to the dynamic relationship between oil temperature and seawater temperature difference, so as to avoid energy waste or insufficient cooling caused by fixed speed pump.

[0046] The beneficial effects of this technical solution are mainly reflected in the comprehensive optimization of system reliability, control accuracy, and energy consumption management. Firstly, by strictly maintaining the hydraulic oil temperature within the optimal operating range of 40℃ to 60℃, it directly solves the problem of drastic viscosity changes in traditional marine hydraulic systems caused by large fluctuations in ambient temperature. This prevents oil oxidation and deterioration at high temperatures and accelerated aging of seals, while also avoiding pump cavitation or response delays caused by excessive viscosity during low-temperature startup, significantly extending the service life of the main pump, digital hydraulic valve group 42, and seals. Secondly, the stable oil temperature ensures a constant bulk modulus of the hydraulic medium, which is crucial for the digital hydraulic valve group 42, which relies on precise flow control. This eliminates the nonlinear error between the PWM duty cycle and the actual flow rate caused by oil temperature drift, thereby ensuring the repeatability accuracy of the position control of the hydraulic drive unit 11. Furthermore, the variable frequency regulation mechanism based on oil temperature feedback enables on-demand distribution of cooling energy. Compared to traditional constant flow cooling, this significantly reduces the ineffective power consumption of the seawater pump, alleviates the load on the platform's power grid, and avoids the risk of hydraulic oil condensate mixing due to over-cooling, improving the inherent safety and operational efficiency of the system in the low-temperature environment of the deep sea.

[0047] In some embodiments, the device is installed between the traveling block and the hook, or between the top drive unit and the derrick. The axis of the compensation actuator 1 coincides with the axis of the drill string.

[0048] In practical implementation, the technical solution of directly connecting the compensation actuator 1 in series with the drill string load-bearing chain is mainly achieved through two typical mechanical layouts. The first implementation involves installing the entire compensation actuator 1 between the traveling block and the hook. In this case, the housings of the hydraulic drive unit 11 and the electric drive unit 12 are fixed to the bottom of the traveling block, while the piston rod is directly connected to the hook. The drill string load is entirely borne by the piston rod. This layout makes the device a direct component of the drill string lifting system, enabling it to directly sense and counteract the vertical movement of the drill string. The second implementation, for top-drive drilling systems, involves inverting the compensation actuator 1 between the top of the derrick and the top drive unit. An extended piston rod is used to connect downwards to the top drive unit. In this case, the axis of the device must be strictly aligned with the wellbore center. This is typically ensured by installing a precision guide sleeve at the top of the derrick or using a self-aligning ball joint structure. This ensures that during hook lifting or lowering, the thrust of the actuator always acts along the drill string axis, avoiding the generation of component forces. In both layouts, the key implementation technology lies in ensuring "coaxiality". For example, the connecting end face of the piston rod is machined by deep hole boring process, and a laser alignment instrument is used for fine adjustment during installation to ensure that the parallelism error between the hydraulic cylinder and the drill string axis is controlled within a very small range, thereby preventing the seal from wearing out or the piston rod from bending due to eccentric force.

[0049] The beneficial effects of this technical solution mainly stem from the optimization of the force transmission path and the elimination of lateral interference. First, because the axis of the compensation actuator 1 is strictly coincident with the drill string axis, the compensation force generated by the hydraulic drive unit 11 and the electric drive unit 12 acts directly on the center of gravity axis of the drill string, completely avoiding the bending moment caused by the lever arm in traditional lateral compensation devices. This bending moment can easily cause the slender drill string to buckle and become unstable or to generate severe friction with the blowout preventer / wellbore in deep-sea operations. The coaxial design ensures that the drill string only bears pure axial force during the compensation process, significantly reducing the wear rate between the drill string and the wellbore and extending the life of the drill string. Second, by directly installing the device between the traveling block and the hook or between the derrick and the top drive, making it the main load-bearing component, additional auxiliary support structures are eliminated, simplifying the system layout. At the same time, the pressure sensor 23 in the multi-source sensing module 2 can directly measure the actual suspended weight of the drill string without interference from other intermediate links, improving the authenticity of the load feedback and the control accuracy. Furthermore, this compact coaxial series design significantly reduces the lateral dimensions of the device, allowing it to fit into the narrow spaces inside the derrick and avoiding interference with other equipment such as overhead cranes and traveling blocks. It also reduces the overall height and weight of the device, minimizing its impact on the stability of the drilling platform. Finally, by ensuring the coaxial transmission of force, the system does not excite lateral vibration modes in the drill string during high-frequency fine-tuning, fundamentally solving the potential "stuck" phenomenon during compensation and ensuring the continuity and safety of deep-sea drilling operations under high sea states.

[0050] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this specification. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0051] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wave compensation device for drilling platforms, characterized in that, include: The compensation actuator (1) includes a hydraulic drive unit (11) and an electric drive unit (12). The hydraulic drive unit (11) is used to provide low-frequency coarse adjustment compensation force, and the electric drive unit (12) is connected in parallel with the hydraulic drive unit (11) to provide high-frequency fine adjustment compensation force. The multi-source sensing module (2) includes an inertial measurement unit (21) for acquiring the platform's motion attitude, a wave detection unit (22) for acquiring wave information, and a pressure sensor (23) for acquiring the drill string load. The control module (3) is connected to the multi-source sensing module (2) and the compensation actuator (1) respectively. The control module (3) is configured to generate composite control commands based on the feedforward signal of the wave detection unit (22), the feedback signal of the inertial measurement unit (21) and the load signal of the pressure sensor (23) through a model predictive control algorithm. A hydraulic power station (4) is connected to the hydraulic drive unit (11) via a proportional oil supply line (41). A digital hydraulic valve group (42) is provided on the proportional oil supply line (41). The digital hydraulic valve group (42) adjusts the flow rate and pressure entering the hydraulic drive unit (11) according to the composite control command.

2. The wave compensation device for drilling platforms according to claim 1, characterized in that, The electric drive unit (12) is a linear motor or a voice coil motor. The stator of the electric drive unit (12) is fixed to the drilling platform deck. The mover of the electric drive unit (12) is coaxially connected to the piston rod of the hydraulic drive unit (11) through a spline or guide shaft. The stroke of the linear motor is less than 10% of the stroke of the hydraulic drive unit (11), and the response frequency is greater than 50Hz.

3. The wave compensation device for drilling platforms according to claim 2, characterized in that, The digital hydraulic valve group (42) includes a preset number of high-speed switching solenoid valves, which operate in PWM pulse width modulation mode; The control module (3) is configured to convert the composite control command into a PWM duty cycle signal to drive the on / off state of the high-speed switching solenoid valve, so as to realize digital quantitative control of the speed of the hydraulic drive unit (11).

4. The wave compensation device for drilling platforms according to claim 3, characterized in that, It also includes an adaptive accumulator assembly, which is connected in parallel to the proportional oil supply line (41); The adaptive accumulator assembly includes a main accumulator and an auxiliary cylinder. The auxiliary cylinder is connected to the nitrogen chamber of the main accumulator through an air passage, and a regulating valve is provided on the air passage. The control module (3) adjusts the opening of the regulating valve according to the drill string suspension signal detected by the pressure sensor (23) to dynamically change the equivalent pre-charge pressure of the main accumulator.

5. The wave compensation device for drilling platforms according to claim 4, characterized in that, The specific execution logic of the control module (3) is as follows: S1: Establish the transfer function model of wave disturbance and platform motion; S2: Based on the data from the wave detection unit (22), the data is input into the transfer function model to generate a predicted displacement curve; S3: Fuse the predicted displacement curve with the actual attitude data, and estimate the remaining wave disturbance through the disturbance observer; S4: Distribute the low-frequency component to the hydraulic drive unit (11) and the high-frequency component to the electric drive unit (12).

6. The wave compensation device for drilling platforms according to claim 5, characterized in that, The hydraulic drive unit (11) includes a hydraulic cylinder and a piston rod, and the piston rod is provided with a mechanical safety lock at the end; The mechanical safety lock is a power failure braking electromagnetic brake. When the control module (3) detects that the system is powered down, communication is interrupted, or the vibration acceleration exceeds a preset threshold, the mechanical safety lock automatically locks the piston rod.

7. The wave compensation device for drilling platforms according to claim 6, characterized in that, The digital hydraulic valve assembly (42) is integrally formed inside the valve block substrate using additive manufacturing process to form an integrated flow channel; The integrated flow channel includes an oil inlet, an oil return port, a working oil port, and an oil drain port. The oil inlet, the oil return port, the working oil port, and the oil drain port are directly connected to the high-speed switching solenoid valve through an internal channel.

8. The wave compensation device for drilling platforms according to claim 7, characterized in that, The multi-source sensing module (2) also includes a proximity switch disposed on the top of the drill string for detecting the lateral offset of the drill string; The control module (3) is configured to limit the output power of the electric drive unit (12) and adjust the center oil pressure of the hydraulic drive unit (11) to provide radial straightening force when the lateral offset exceeds a safety threshold.

9. The wave compensation device for drilling platforms according to claim 8, characterized in that, The hydraulic power station (4) includes a main pump, a motor, and a cooling circulation loop; The cooling circulation loop includes a plate heat exchanger and a seawater cooling pipeline. The control module (3) adjusts the flow rate of the seawater cooling pipeline according to the oil temperature sensor data to keep the hydraulic oil temperature within the range of 40℃-60℃.

10. The wave compensation device for drilling platforms according to any one of claims 1 to 9, characterized in that, The device is installed between the traveling block and the hook, or between the top drive unit and the derrick. The axis of the compensation actuator (1) coincides with the axis of the drill string.

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