A large borehole axial shock absorber

Abstract

This invention belongs to the field of shock absorber technology and relates to a large-size wellbore axial shock absorber, including an upper connector, a housing, and a lower connector. The housing is fitted onto the outer wall of the upper connector, and a receiving cavity is formed between the inner wall of the housing and the outer wall of the upper connector. A disc spring shock absorber assembly is installed in the receiving cavity. A hydraulic shock absorber assembly is connected to the bottom of the housing, and the lower connector is connected to the bottom of the hydraulic shock absorber assembly. The hydraulic shock absorber assembly includes a hydraulic shell, a piston, and a hydraulic sealing seat. The hydraulic shell is fitted onto the bottom of the housing, and the hydraulic sealing seat communicates with the bottom of the hydraulic shell and forms a hydraulic cavity inside. The piston slides through the hydraulic sealing seat and is slidably disposed in the hydraulic cavity. The piston has a hydraulic through hole, and an electromagnetic proportional valve is connected to the hydraulic through hole. This invention improves the problem of existing technology's single shock absorber element and fixed parameters, which are difficult to adapt to the vibration characteristics of large-size wellbores, by combining disc spring and hydraulic shock absorption, adaptive stiffness of shape memory alloy adjustment plate, and active adjustment by electromagnetic proportional valve.

Description

Technical Field

[0001] This invention relates to the field of shock absorber technology, and more specifically, to a large-size wellbore axial shock absorber. Background Technology

[0002] As oil and gas exploration and development moves towards deeper, ultra-deep, and complex formations, axial vibration and torsional stick-slip vibration are particularly prominent in large-diameter wellbore (12-1 / 2 inches and above) drilling operations. These issues are caused by factors such as the interaction between the drill bit and the rock, changes in formation hardness, and unreasonable drilling parameters. This can easily lead to problems such as drill string fatigue fracture, increased drill bit wear, and reduced mechanical drilling speed. Existing shock absorbers are mostly designed for conventional-sized wellbores, and their damping stiffness, stroke, and other parameters are poorly matched to the working conditions of large-diameter wells. Moreover, they often use a single damping element, which is difficult to cope with the severe and complex multi-directional vibrations of large-diameter wells. At the same time, the fixed damping parameters cannot be adapted to the dynamic vibration characteristics of the formation in real time, and the sealing structure is also difficult to adapt to the high temperature, high pressure, and complex motion conditions of large-diameter wells. They are prone to failure, and the overall structure is not disassembled, resulting in high maintenance costs, making it difficult to meet the damping requirements of large-diameter wells.

[0003] Therefore, existing technologies suffer from problems such as the inability to adaptively adjust damping parameters, the use of a single damping element, insufficient sealing reliability, and inconvenient maintenance. Summary of the Invention

[0004] This invention provides a large-size wellbore axial shock absorber, which solves the problems of existing technologies such as the inability to adaptively adjust shock absorption parameters, the use of a single shock absorption element, and insufficient sealing reliability.

[0005] The technical solution of the present invention is as follows:

[0006] A large-size wellbore axial damper includes: an upper connector, a housing, and a lower connector. The housing is fitted onto the outer wall of the upper connector, and a receiving cavity is formed between the inner wall of the housing and the outer wall of the upper connector. A disc spring damping assembly is disposed within the receiving cavity. A hydraulic damping assembly is connected to the bottom of the housing, and the lower connector is connected to the bottom of the hydraulic damping assembly. The hydraulic damping assembly includes a hydraulic housing, a piston, and a hydraulic sealing seat. The hydraulic housing is fitted onto the bottom of the housing, and the hydraulic sealing seat communicates with the bottom of the hydraulic housing and forms a hydraulic cavity inside. The piston passes through the hydraulic sealing seat and is slidably disposed within the hydraulic cavity. The piston has a hydraulic through hole, and an electromagnetic proportional valve is connected within the hydraulic through hole.

[0007] Furthermore, the disc spring damping assembly includes a disc spring group, with a pad abutting at both the top and bottom of the disc spring group. The pad has an installation groove, and a shape memory alloy adjustment piece is disposed in the installation groove.

[0008] Furthermore, a rubber cylinder abuts against the disc spring assembly and the hydraulic housing, the rubber cylinder having through holes evenly distributed on its wall and a spiral cut on its wall.

[0009] Furthermore, it also includes an adjustment assembly, which includes a vibration sensor and a processor. The vibration sensor is electrically connected to the processor, and the processor is electrically connected to the electromagnetic proportional valve. Both the vibration sensor and the processor are disposed inside the piston.

[0010] Furthermore, the inner wall of the housing is provided with a keyway, and the outer wall of the upper connector is provided with an external spline that engages with the keyway, so that the housing and the upper connector are circumferentially fixedly connected.

[0011] Furthermore, piezoelectric ceramic sheets are evenly distributed within the spiral cut, and these piezoelectric ceramic sheets are electrically connected to both the vibration sensor and the processor. The piezoelectric ceramic sheets are used to convert vibration energy into electrical energy to power the vibration sensor and the processor.

[0012] Furthermore, the keyway teeth are provided with a spiral groove, which is filled with a wear-resistant material. The spiral groove and the wear-resistant material together form a composite spiral groove. The composite spiral groove dissipates torsional vibration energy through the friction of the relative rotation of the spline mating surfaces, thereby achieving torsional vibration attenuation.

[0013] Furthermore, sealing grooves are provided at the connection between the hydraulic housing and the upper connector, and at the connection between the hydraulic housing and the hydraulic sealing seat. A composite sealing assembly is provided in the sealing groove, and the composite sealing assembly includes a main sealing ring, a secondary sealing ring, a guide ring, and a dustproof ring connected in sequence.

[0014] Furthermore, the processor has a built-in database of typical formation vibration characteristics for large-size wellbores. The processor is configured to compare and analyze the axial vibration signal collected by the vibration sensor with the database of typical formation vibration characteristics for large-size wellbores to determine the vibration mode of the next stage of drilling operations, and output control commands to adjust the valve opening of the electromagnetic proportional valve according to the prediction results, so as to adjust the hydraulic damping.

[0015] Furthermore, the piezoelectric ceramic sheet has an arc-shaped sheet structure with a curvature that matches the spiral cut. The surface of the piezoelectric ceramic sheet is nickel-plated to form a bottom protective layer, and a polytetrafluoroethylene coating is applied to the outside of the bottom protective layer to form a top protective layer.

[0016] In summary, the present invention has the following beneficial effects:

[0017] First, the present invention connects the disc spring damping component and the hydraulic damping component in series, and sets a hydraulic through hole and an electromagnetic proportional valve on the piston, so that the axial vibration can be dissipated by the elastic deformation of the disc spring and the hydraulic damping. The damping force can be adjusted by the valve opening, realizing graded damping and adjustable damping, which is beneficial to adapting to different axial vibration conditions in large-size well holes.

[0018] Secondly, this invention utilizes a shape memory alloy adjusting plate to change the working clearance of the disc spring assembly according to the vibration amplitude, thereby achieving adaptive matching of damping stiffness; the rubber cylinder combined with the spiral cut takes into account both axial and torsional vibration energy dissipation; the built-in vibration sensor and processor can predict and actively adjust the damping according to the ground vibration characteristics; and the piezoelectric ceramic sheet recovers vibration energy to power the electronic control system, reducing dependence on external power sources.

[0019] In addition, by setting a composite spiral groove on the keyway tooth surface, the friction effect when the spline mating surfaces rotate relative to each other dissipates the torsional stick-slip vibration energy, which helps to attenuate torsional vibration; the composite sealing assembly composed of main and auxiliary sealing rings, guide rings and dustproof rings enhances the sealing reliability of the hydraulic cavity under high temperature, high pressure and compound motion, and provides a stable working environment for damping adjustment.

[0020] In summary, this invention improves upon the problems of existing technologies, such as the single damping element and fixed parameters, which are difficult to adapt to the vibration characteristics of large-diameter wells, by combining disc spring damping components with hydraulic damping components, adaptive stiffness of shape memory alloy adjusting plates, and active damping adjustment of electromagnetic proportional valves. The composite spiral groove and rubber sleeve provide a torsional energy dissipation path, the composite sealing component enhances the sealing reliability under high temperature and high pressure, and the detachable shell structure facilitates downhole maintenance. Thus, it comprehensively improves the problems of existing technologies, such as the inability to adaptively adjust damping parameters, the single damping element, insufficient sealing reliability, and inconvenient maintenance. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a perspective view of the shock absorber provided by the present invention;

[0023] Figure 2 This is a front view of the shock absorber provided by the present invention;

[0024] Figure 3 This is a cross-sectional view of the shock absorber provided by the present invention;

[0025] Figure 4This invention provides Figure 3 A magnified view of a portion of point A in the middle;

[0026] Figure 5 This invention provides Figure 3 A magnified view of a portion of point B in the middle.

[0027] Figure 6 This invention provides Figure 3 A magnified view of a portion of point C in the middle;

[0028] Figure 7 This is a schematic diagram of the hydraulic shock absorption component structure of the shock absorber provided by the present invention;

[0029] Figure 8 This is a schematic diagram of the structure of the gasket and shape memory alloy adjusting plate provided by the present invention;

[0030] Figure 9 This is a three-dimensional structural schematic diagram of the rubber cylinder provided by the present invention;

[0031] Figure 10 This is a front view of the rubber cylinder provided by the present invention;

[0032] Figure 11 This invention provides Figure 10 A magnified view of a portion of point D.

[0033] Legend:

[0034] 1-Upper connector; 2-Housing shell; 3-Hydraulic housing; 4-Lower connector; 5-Oil injection hole; 6-External spline; 7-Disc spring assembly; 8-Gasket; 9-Rubber sleeve; 91-Helical cut; 92-Piezoelectric ceramic plate; 10-Piston; 11-Hydraulic sealing seat; 12-Memory alloy adjusting plate; 13-First composite sealing assembly; 14-Second composite sealing assembly; 15-Hydraulic chamber; 16-Hydraulic through hole; 17-Electromagnetic proportional valve; 18-Composite helical groove; 19-Vibration sensor. Detailed Implementation

[0035] In the description of this invention, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0036] Example

[0037] The following is in conjunction with the appendix Figure 1-11 The present invention will be further described in detail below.

[0038] This embodiment provides a large-size wellbore axial shock absorber, including: an upper connector 1, a housing 2 and a lower connector 4. The housing 2 is sleeved on the outer wall of the upper connector 1, and a receiving cavity is formed between the inner wall of the housing 2 and the outer wall of the upper connector 1. A disc spring shock absorber is provided in the receiving cavity. A hydraulic shock absorber is connected to the bottom of the housing 2, and the lower connector 4 is connected to the bottom of the hydraulic shock absorber.

[0039] The hydraulic shock absorber assembly includes a hydraulic housing 3, a piston 10, and a hydraulic sealing seat 11. The hydraulic housing 3 is fitted onto the bottom of the housing 2. The hydraulic sealing seat 11 is connected to the bottom of the hydraulic housing 3 and has a hydraulic chamber 15 inside. The piston 10 passes through the hydraulic sealing seat 11 and is slidably disposed in the hydraulic chamber 15. The piston 10 has a hydraulic through hole 16, and an electromagnetic proportional valve 17 is connected in the hydraulic through hole 16.

[0040] The housing 2 and the upper connector 1 are fitted together by a spline, and are arranged coaxially to ensure coaxiality during relative movement. The bottom of the housing 2 and the hydraulic housing 3 of the hydraulic shock absorber are detachably connected to facilitate the assembly and maintenance of internal components. The hydraulic housing 3 and the lower connector 4 are connected by threads, and the hydraulic sealing seat 11 is connected to the bottom of the hydraulic housing 3 by a sealed connection, so that the hydraulic chamber 15 forms a closed space for the hydraulic medium. The piston 10 and the hydraulic sealing seat 11 are fitted with a sliding seal and can slide back and forth along the axial direction of the hydraulic chamber 15. The hydraulic through hole 16 is opened through the piston 10 along the axial direction. The electromagnetic proportional valve 17 is embedded in the hydraulic through hole 16, and its valve opening can be adjusted to control the flow of hydraulic medium.

[0041] Preferably, the electromagnetic proportional valve 17 is a high-temperature and high-pressure valve with a temperature resistance of 200℃ and a pressure resistance of 35MPa, and the vibration sensor 19 is packaged with an IP68 protection rating to adapt to harsh downhole working conditions.

[0042] During drilling operations, the drilling pressure of this invention is transmitted via the upper connector 1 to the disc spring damping assembly and the hydraulic damping assembly, and then to the drill bit via the lower connector 4. When the drill string experiences axial vibration, the disc spring damping assembly absorbs and dissipates some of the vibration energy through elastic deformation. Simultaneously, the vibration drives the piston 10 in the hydraulic damping assembly to slide back and forth within the hydraulic chamber 15. The hydraulic medium flows through the hydraulic through-hole 16 on both sides of the piston. The electromagnetic proportional valve 17 controls the flow area of ​​the hydraulic medium by adjusting the valve opening, generating a damping force corresponding to the vibration speed, thus converting the mechanical energy of the vibration into heat energy for dissipation. The elastic buffering of the disc spring damping assembly and the damping energy dissipation of the hydraulic damping assembly work together to achieve the attenuation of axial vibration.

[0043] Furthermore, the inner wall of the housing 2 is provided with a keyway, and the outer wall of the upper connector 1 is provided with an external spline 6 that engages with the keyway, so that the housing 2 and the upper connector 1 are circumferentially fixedly connected.

[0044] In this embodiment, the keyway extends axially along the inner wall of the housing 2, and the external spline 6 extends axially along the outer wall of the upper connector 1. The tooth profile parameters of the two are matched with each other. After meshing, the housing 2 and the upper connector 1 are circumferentially fixed, which can transmit the torque during the drilling process and prevent the two from rotating relative to each other. At the same time, the keyway and the external spline 6 adopt a clearance meshing fit, so that the housing 2 and the upper connector 1 can slide relative to each other in the axial direction without affecting the axial damping stroke of the disc spring damping assembly.

[0045] Preferably, in this embodiment, the upper connector 1 is made of 42CrMo alloy steel, with an outer diameter of 126.4mm and an inner diameter of 75mm at the critical section. The upper connector 1 has a tensile safety factor ≥2.98 and a torsional safety factor ≥2.58 to prevent fatigue fracture of the upper connector 1 during drilling. The housing 2 is also made of 42CrMo alloy steel, with 8 spline teeth. When the housing 2 and the upper connector 1 are in a dynamic connection (axial relative sliding, circumferential fixed) state, the keyway extrusion pressure is controlled at ≤19.60MPa to prevent plastic deformation of the spline teeth. The safety factor of this spline fit should be ≥48.47 to stably bear the circumferential torque and axial load during the drilling process of large-diameter wells, adapt to the complex downhole working conditions of 200℃ high temperature and 300kN high pressure, ensure the continuity and reliability of spline meshing transmission, avoid failure problems such as spline tooth breakage and keyway damage, and further improve the overall service life of the shock absorber.

[0046] It is worth noting that in this embodiment, the outer wall of the housing 2 is provided with an oil injection hole 5, which is used to inject lubricating oil into the disc spring damping assembly.

[0047] Furthermore, the tooth surface of the keyway is provided with a spiral groove, which is filled with wear-resistant material. The spiral groove and the wear-resistant material together form a composite spiral groove 18. The composite spiral groove 18 dissipates torsional vibration energy through the friction of the relative rotation of the spline mating surfaces, thereby achieving torsional vibration attenuation.

[0048] In this embodiment, the spiral groove is spirally opened along the axial direction of the keyway tooth surface, and the wear-resistant material is filled inside the spiral groove and flush with the tooth surface to form a composite spiral groove 18. When the drill string generates torsional stick-slip vibration, the mating surfaces of the keyway and the external spline 6 rotate relative to each other, and the tooth surface of the composite spiral groove 18 and the tooth surface of the external spline 6 generate friction, converting the energy of the torsional vibration into heat energy dissipation, thereby attenuating the torsional vibration and reducing the fatigue wear of the drill bit.

[0049] Preferably, in this embodiment, the wear-resistant material in the spiral groove is graphite-polytetrafluoroethylene.

[0050] Furthermore, the disc spring damping assembly includes a disc spring assembly 7, with a pad 8 abutting at both the top and bottom of the disc spring assembly 7. The pad 8 has an installation groove, and a shape memory alloy adjustment piece 12 is provided in the installation groove.

[0051] In this embodiment, the disc spring assembly 7 is formed by coaxially stacking several disc springs, and the stacking method is adapted according to the damping stiffness requirements. The gasket 8 is a ring structure, which abuts against the upper and lower ends of the disc spring assembly 7 to transmit axial load. The mounting groove is opened circumferentially along the end face of the gasket 8, and the shape memory alloy adjusting plate 12 is embedded in the mounting groove and fixedly connected to the gasket 8. When the load generated by drilling vibration acts on the disc spring assembly 7, the shape memory alloy adjusting plate 12 can deform according to the vibration condition, thereby adjusting the compression of the disc spring assembly 7, changing the working distance of the disc spring assembly 7, and realizing the adaptive adjustment of the damping stiffness.

[0052] Preferably, in this embodiment, the disc spring assembly 7 is made of a non-standard disc spring with an outer diameter of 225mm, an inner diameter of 127mm, and a base thickness of 12mm. After precision machining, the thickness is reduced to 11.5mm. The height of the disc spring in its free state is 16.5mm, and the flattening deformation is 4.5mm. The disc spring is made of 60Si2MnA material and undergoes surface manganese phosphating treatment to improve fatigue resistance and wear resistance. The disc spring assembly uses two pieces stacked together as a basic unit, with a total of 60 basic units used together. After assembly, the total length of the disc spring assembly 7 is 1680mm. To ensure the service life and vibration damping stability of the disc spring assembly 7, its working compression is controlled at 0.2 to 0.75 times the ultimate compression. During operation, the stiffness is maintained within the range of 1.96 to 2.21 kN / mm, which is suitable for the axial vibration load requirements of large-diameter wells. The shape memory alloy adjusting plate 12 is made of Ni-Ti alloy and has deformation triggering and stiffness adjustment characteristics. When the axial vibration amplitude exceeds 15mm during drilling, the shape memory alloy adjusting plate 12 undergoes preset deformation due to vibration heat, automatically changing the mating gap of the disc spring assembly 7. The deformation of the shape memory alloy adjusting plate 12 can adaptively increase the stiffness of the disc spring assembly 7 by 20% to 40%, which can achieve the matching of vibration damping stiffness with severe vibration conditions and effectively improve the vibration damping effect.

[0053] Furthermore, a rubber cylinder 9 abuts between the disc spring assembly 7 and the hydraulic housing 3. The wall of the rubber cylinder 9 is evenly distributed with through holes, and the wall of the rubber cylinder 9 is provided with a spiral cut 91.

[0054] The rubber cylinder 9 is coaxially sleeved between the disc spring assembly 7 and the hydraulic housing 3. Gaskets 8 are abutted at both its top and bottom. The upper end face of the rubber cylinder 9 abuts against the lower end face of the gasket 8 at the bottom of the disc spring assembly 7, and the lower end face abuts against the upper end face of the gasket 8 at the top of the hydraulic housing 3, serving to buffer the axial impact between the disc spring assembly 7 and the hydraulic housing 3. Through holes are evenly distributed circumferentially along the wall of the rubber cylinder 9, and spiral cuts 91 are spirally opened along the wall of the rubber cylinder 9. The through holes and spiral cuts 91 cooperate with each other, allowing the rubber cylinder 9 to undergo elastic deformation under axial force, assisting in absorbing axial vibration energy and simultaneously improving the deformation adaptability of the rubber cylinder 9.

[0055] Preferably, in this embodiment, the rubber sleeve 9 is made of fluororubber to adapt to the downhole working conditions of large-size wellbores with high temperatures of 200°C and high pressures of 300kN. The wall of the rubber sleeve 9 has circumferential through holes with various shapes including circular, elliptical, and waist-shaped holes, with a diameter of 2-8mm to adapt to the energy dissipation requirements of different vibration intensities. The rubber sleeve 9 and the gasket 8, with a thickness in the range of 5-30mm, are assembled in an alternating overlapping manner to improve the structural adaptability and energy dissipation capacity of the rubber sleeve 9. The wall of the rubber sleeve 9 adopts a spiral cut 91 structure design, which can simultaneously meet the dual requirements of axial viscoelastic energy dissipation and torsional shear deformation energy dissipation. The rubber sleeve 9 utilizes the superelastic and viscoelastic properties of fluororubber itself. When subjected to drilling vibration loads, the internal molecular chains of the fluororubber are coiled and slipped, combined with the shear deformation of the spiral cut 91 on the rubber sleeve 9, to achieve synchronous absorption and dissipation of axial and torsional vibration energy, further improving the damping effect of the shock absorber on multi-directional vibrations.

[0056] Furthermore, it also includes an adjustment component, which includes a vibration sensor 19 and a processor. The vibration sensor 19 is electrically connected to the processor, and the processor is electrically connected to the electromagnetic proportional valve 17. Both the vibration sensor 19 and the processor are disposed inside the piston 10.

[0057] Furthermore, the processor has a built-in database of typical formation vibration characteristics for large-size wellbores. The processor is configured to compare and analyze the axial vibration signal collected by the vibration sensor 19 with the database of typical formation vibration characteristics for large-size wellbores to determine the vibration mode of the next stage of drilling operations. Based on the prediction results, the processor outputs control commands to adjust the valve opening of the electromagnetic proportional valve 17 to adjust the hydraulic damping.

[0058] The piston 10 has a chamber for installing the adjustment components. The vibration sensor 19 and the processor are both fixedly installed in this chamber. The chamber is sealed to isolate the downhole hydraulic medium and impurities. The processor has a built-in large-size typical formation vibration feature library of the wellbore. The vibration sensor 19 is used to collect axial vibration signals during the drilling process in real time and transmit the signals to the processor. The processor compares and analyzes the received vibration signals with the large-size typical formation vibration feature library of the wellbore. Then, based on the matching results, it predicts the vibration mode of the next stage of drilling operation. Subsequently, the processor directly outputs control commands based on the prediction results to adjust the valve opening of the electromagnetic proportional valve 17 to adjust the hydraulic damping.

[0059] The hardware connection and control method of the adjustment component in this embodiment will be further described below:

[0060] I. Hardware connection and wiring;

[0061] The piston 10 has an axial wiring groove inside. After the wire is embedded in the groove, it is fixed with high-temperature resistant silicone. The wiring direction is parallel to the hydraulic through hole 16, avoiding the sealing groove and the moving contact surface, so as to ensure that there is no wire pulling when the piston 10 reciprocates.

[0062] The processor and the electromagnetic proportional valve 17 are connected using PTFE-insulated silver-plated copper wires that are resistant to 200℃ high temperature and drilling fluid corrosion. The wires are wrapped with fluororubber protective sleeves to prevent direct contact between the wires and the hydraulic medium, which could lead to wire aging. The terminals of the processor and the electromagnetic proportional valve 17 are fixed by welding and potting. The two ends of the wires are welded to the processor I / O interface and the control coil pin of the electromagnetic proportional valve, respectively. The weld points are coated with high-temperature epoxy potting compound to prevent vibration from causing desoldering.

[0063] II. Processor Control Flow

[0064] The processor performs closed-loop regulation of the valve opening of the electromagnetic proportional valve 17 based on the real-time vibration signal. The specific control logic is as follows:

[0065] 1. Control parameter settings

[0066] Adjust the trigger threshold: The vibration sensor detects a change in vibration frequency ≥ 0.5 Hz or a change in vibration amplitude ≥ 2 mm;

[0067] Valve opening adjustment range: 0~100%, corresponding to a flow area of ​​0~8mm²;

[0068] Adjustment step size: 5% / time for normal working conditions (amplitude < 15mm), 8% / time for severe vibration conditions with amplitude ≥ 15mm;

[0069] Damping coefficient mapping: There is a linear mapping between the valve opening of the electromagnetic proportional valve 17 and the damping coefficient. 0% opening corresponds to a damping coefficient of 3.5kN·s / m, 100% opening corresponds to a damping coefficient of 0.8kN·s / m, and the damping coefficient decreases by 0.3kN·s / m for every 10% increase in opening.

[0070] Adjustable response time: ≤0.3s;

[0071] Locking condition: If the vibration frequency and vibration amplitude do not exceed the adjustment trigger threshold within 500ms after adjustment, the processor locks the current valve opening to avoid wear caused by frequent adjustments.

[0072] 2. Signal Acquisition and Operating Condition Determination

[0073] The processor acquires vibration signals from the vibration sensor 19 at a frequency of 200 sets per second, and uses a Kalman filter algorithm to remove drilling fluid pulse interference, obtaining smooth frequency and amplitude signals.

[0074] If the vibration parameters are within the adjustment threshold range, the current valve opening remains unchanged. If the vibration parameters exceed the threshold, the processor extracts the time-domain feature parameters of the real-time signal (including the mean frequency, peak amplitude, standard deviation of amplitude, torque fluctuation range, and peak factor), and after normalization, forms a feature vector, which is then matched with the built-in typical formation vibration feature library for large-size wells.

[0075] The matching algorithm uses dynamic time warping to calculate the similarity between the real-time feature vector and each standard vector in the feature library. The matching rules are as follows:

[0076] If the similarity of a certain stratum is ≥85%, the optimal damping parameters corresponding to that stratum are directly used.

[0077] If the similarity of all strata is <85% but the highest value is ≥70%, the damping coefficient corresponding to that stratum is reduced by 10% and the valve opening is increased by 10%, leaving a safety margin.

[0078] If the similarity of all formations is less than 70%, the conservative mode is activated, and the valve opening is locked at 30% (corresponding to a damping coefficient of 2.6 kN·s / m). At the same time, the processor records the vibration characteristics and adds them to the feature library after the tool is pulled out of the hole, thus achieving adaptive updates.

[0079] To avoid instability caused by frequent switching, the matching operation is performed every 200ms.

[0080] 3. Opening adjustment and closed-loop correction

[0081] The target opening is calculated based on the preset damping coefficient-valve opening mapping relationship, and then adjusted step by step to the target value. After adjustment, the processor collects the pressure signal of hydraulic chamber 15 in real time through the built-in pressure sampling module. If the actual damping coefficient deviates from the target value by ≥0.1kN·s / m, a supplementary adjustment is performed in 2% steps.

[0082] 4. Coordinated control with shape memory alloy adjustment plates

[0083] When the shape memory alloy adjustment plate 12 is triggered to deform due to a vibration amplitude ≥15mm, the processor simultaneously increases the adjustment step size from 5% to 8% and lowers the target damping coefficient by 10% to avoid resonance after the system stiffness is increased.

[0084] III. Regarding the database of ground vibration characteristics;

[0085] The large-diameter wellbore typical formation vibration feature library built into the processor described above can be pre-constructed using the following exemplary methods:

[0086] (1) Data Acquisition

[0087] For large-diameter wellbore blocks, downhole vibration sensors and data loggers are used to continuously collect vibration response data, such as axial vibration frequency, vibration amplitude, and torque fluctuation range, for different typical formations (e.g., sandstone, mudstone, and gravel layers) during drilling, forming field-measured samples. For extreme conditions that are difficult to simulate in the field, supplementary experiments can be conducted using a large-diameter wellbore vibration simulation test bench, or a coupled "drill string-drill bit-formation" model can be established through drill string dynamics simulation to generate simulation data as a supplement.

[0088] (2) Feature extraction

[0089] After denoising and normalizing the collected raw vibration data, key parameters characterizing the ground vibration properties are extracted to construct a multidimensional feature vector. A typical feature vector can contain three dimensions: mean frequency, peak amplitude, and torque fluctuation range.

[0090] (3) Parameter association and database construction

[0091] For each typical formation, the optimal damping parameters (including at least the target valve opening and target damping coefficient of the electromagnetic proportional valve) that achieve the best damping effect under the formation conditions are determined through experiments or simulations. The extracted feature vectors are associated with the corresponding optimal damping parameters, and stored according to formation type to form a feature library that can be called in real time during drilling operations. For example, the gravel layer can correspond to the feature vector [8.5Hz, 16mm, 18~22kN·m], and match the optimal damping parameters [valve opening 60%, damping coefficient 1.5kN·s / m].

[0092] The specific sensor selection, filtering algorithms, normalization methods, simulation software operation, and correlation optimization methods used in the aforementioned data acquisition, processing, feature extraction, and database construction processes are all existing technologies in this field. The completed feature library is pre-built into the processor, eliminating the need for ground signal transmission and interaction, effectively reducing signal interference in the complex downhole environment. All operations are autonomously completed within the shock absorber, realizing a shift in shock absorption adjustment from real-time feedback to proactive prediction. This allows for advance adaptation to the dynamically changing vibration characteristics of the formation, improving the timeliness and adaptability of the shock absorption response.

[0093] Furthermore, piezoelectric ceramic sheets 92 are evenly distributed within the spiral cut 91. The piezoelectric ceramic sheets 92 are electrically connected to the vibration sensor and the processor. The piezoelectric ceramic sheets 92 are used to convert vibration energy into electrical energy to power the vibration sensor and the processor.

[0094] Furthermore, the piezoelectric ceramic sheet 92 has an arc-shaped sheet structure with a curvature that matches the spiral cut 91. The surface of the piezoelectric ceramic sheet 92 is treated with nickel plating to form a bottom protective layer. A polytetrafluoroethylene coating is also applied to the outside of the bottom protective layer to form a top protective layer.

[0095] In this embodiment, the shape of the piezoelectric ceramic sheet 92 is adapted to the shape of the spiral cut 91, and is tightly embedded inside the spiral cut 91 and fixedly connected to the wall of the rubber cylinder 9. When the rubber cylinder 9 is deformed by vibration, the piezoelectric ceramic sheet 92 is simultaneously mechanically excited, and the mechanical energy generated by the vibration is converted into electrical energy by using the positive piezoelectric effect. The generated electrical energy is transmitted to the adjustment component through the wire to provide working power for the vibration sensor 19 and the processor, thereby realizing the recovery and utilization of vibration energy.

[0096] The piezoelectric ceramic sheet 92 adopts an arc-shaped sheet structure with a curvature consistent with the spiral cut 91 of the rubber tube. Its dimensions are 20mm in length, 8mm in width, and 1.5mm in thickness, so as to fit the inner wall of the spiral cut 91 without protruding from the surface of the rubber tube. Its temperature resistance can reach 200℃, its vibration resistance is not less than 100g, its piezoelectric constant d33 is not less than 320pC / N, its surface is nickel-plated to meet the 5%~8% sulfur resistance requirements in downhole wells, and its water pressure resistance is not less than 35MPa.

[0097] The piezoelectric ceramic sheet 92 is bonded and fixed to the inner wall of the spiral cut 91 with a high-temperature epoxy adhesive with a temperature resistance of 250℃. A 0.5mm thick fluororubber buffer layer is placed between the ceramic sheet and the rubber cylinder to absorb high-frequency impact and prevent the ceramic sheet from breaking brittlely.

[0098] The ceramic sheet surface is also coated with a 0.3mm thick polytetrafluoroethylene coating to isolate it from drilling fluid corrosion without affecting deformation transmission. Within the spiral cut 91 of each rubber sleeve, a piezoelectric ceramic sheet 92 is evenly arranged every 30° along the spiral line, totaling 36 sheets forming a ring array. This ensures that at least one-third of the ceramic sheets are simultaneously stressed under both axial and torsional vibrations, guaranteeing continuous and stable energy output. The spiral cut 91 is 10mm wide and 5mm deep, providing ample deformation space for the piezoelectric ceramic sheet 92 to avoid limiting the vibration damping and energy dissipation of the rubber sleeve.

[0099] The adhesive, buffer layer, and rubber sleeve utilize a fluororubber system with matching coefficients of thermal expansion, making them resistant to peeling under high-temperature conditions. The power supply system for the piezoelectric ceramic discs 92 is integrated within the mounting chamber of the piston 10, with an overall volume not exceeding φ20mm × 50mm. The power supply system sequentially includes a piezoelectric array, a rectifier module, an energy storage module, a voltage regulator module, and a load interface. The 36 piezoelectric ceramic discs 92 are divided into 6 groups, with 6 discs in each group connected in series and then in parallel to increase the output voltage and current, meeting the power requirements of the load.

[0100] The rectifier module uses a high-temperature resistant bridge rectifier chip with a temperature resistance of 210℃ to convert the AC power output from the piezoelectric ceramic plate 92 into DC power.

[0101] The energy storage module uses a 200℃-resistant, 10F downhole-specific supercapacitor to balance vibration energy fluctuations and maintain a stable power supply.

[0102] The voltage regulator module uses a high-temperature and low-dropout voltage regulator chip, and outputs dual voltages of 3.3V and 5V. The 3.3V supplies the vibration sensor 19 and the processor, and the 5V supplies the drive unit of the electromagnetic proportional valve 17.

[0103] The power supply wire is made of polytetrafluoroethylene insulated silver-plated copper wire with a diameter of 0.2mm and a temperature resistance of 200℃. It is covered with a stainless steel braided protective sleeve. The wire is led out from the spiral cut 91, passes through the reserved wire hole between the rubber cylinder and the gasket 8, and extends along the axial wiring groove on the inner wall of the housing 2 to the mounting chamber of the piston 10. The two ends of the wire are fixed by welding and potting high-temperature epoxy glue to prevent the piston from detaching due to reciprocating motion.

[0104] The power supply wires are laid separately from the control wires from the processor to the electromagnetic proportional valve 17, with a spacing of no less than 5mm. The control wires use a twisted-pair structure with a twist pitch of 8mm to reduce power interference. The power supply interface uses a miniature board-to-board connector with a temperature resistance of 200℃ for easy assembly and maintenance. The system is equipped with power supply priority and energy redundancy protection. The primary loads are the vibration sensor 19 and the processor, which are given priority in power supply.

[0105] The secondary load is electromagnetic proportional valve 17, which starts working when the supercapacitor voltage is not lower than 4.5V and stops when it is lower than 3.5V to avoid malfunction. When the capacitor voltage is higher than 5.5V, the charging circuit is automatically cut off. When it is lower than 3V, it enters low power mode, reduces the sampling frequency and extends the processor sleep cycle to ensure the continuous operation of the core control function.

[0106] Furthermore, sealing grooves are provided at the connection between the hydraulic housing 3 and the upper connector 1, and at the connection between the hydraulic housing 3 and the hydraulic sealing seat 11. A composite sealing assembly is provided in the sealing groove, which includes a main sealing ring, a secondary sealing ring, a guide ring, and a dustproof ring connected in sequence.

[0107] It is worth noting that the first composite sealing assembly 13 and the second composite sealing assembly 14 have the same structure, but the installation positions are different. The first sealing assembly 13 is located at the connection between the hydraulic housing 3 and the upper connector 1, while the second sealing assembly 14 is located at the connection between the hydraulic housing 3 and the hydraulic sealing seat 11.

[0108] The sealing grooves are respectively opened circumferentially along the mating surfaces of the hydraulic housing 3 and the upper connector 1, and the mating surfaces of the hydraulic housing 3 and the hydraulic sealing seat 11. The groove dimensions are adapted to the shape of the composite sealing assembly. The composite sealing assembly is sequentially embedded in the sealing grooves, and the main sealing ring and the secondary sealing ring cooperate with each other to form a double sealing structure to prevent the medium in the hydraulic chamber 15 from leaking. The guide ring is set on the inner side of the sealing assembly to guide the relatively moving parts and avoid the seal from being worn by the off-center load. The dustproof ring is set on the outer side of the sealing assembly to prevent mud, sand and impurities from the well from entering the sealing mating surface, protect the seal from wear and improve the reliability of the sealing structure.

[0109] The sealing groove is a multi-stage annular groove structure formed in the hydraulic seal seat 11, with a total groove width of 16mm, a total groove depth of 12mm, and a groove wall roughness Ra≤0.8μm. The groove is divided into 4 independent sub-grooves, each adapted to a different sealing component. The sealing groove is CNC machined, with the groove bottom and groove wall perpendicularity ≤0.02mm, and the groove wall hardness ≥HRC60 after nitriding treatment.

[0110] The dust seal is made of PTFE composite material with a rectangular cross-section and a lip structure. It is interference-fitted with the piston and embedded in the outermost sub-groove, with the lip facing outwards, to scrape impurities from the piston surface. The guide ring is made of polyoxymethylene (POM) with a stepped cross-section. It is clearance-fitted with the piston and located inside the dust seal to ensure that the piston is not subjected to off-center load during rotation and reciprocating motion, with a radial offset ≤0.2mm.

[0111] The main sealing ring is made of different materials depending on the drilling fluid type: a polyurethane (PU) Y-shaped cross-section is used for water-based fluids, and a filled PTFE V-shaped cross-section is used for oil-based fluids. Located inside the guide ring, with the lip facing the hydraulic chamber 15, it utilizes the pressure self-tightening effect to withstand 35MPa high pressure, achieving a core seal. The secondary sealing ring uses a fluororubber (FKM) O-ring structure, matched with a rectangular retaining ring, located inside the main sealing ring. A 1mm thick 42CrMo metal retaining ring is installed on its outer side to withstand high temperatures of 200℃ and sulfur environments of 5%~8%, and to prevent high-pressure extrusion of the seal.

[0112] Assembly is carried out in the following order: dust ring, guide ring, main seal ring, secondary seal ring, and retaining ring. The pre-compression of the lip of the main seal ring is 0.4~0.5mm, and the contact pressure between the secondary seal ring and the piston surface is ≥0.3MPa.

[0113] Preferably, in this embodiment, the components of the composite sealing assembly are made of materials suitable for downhole working conditions. The main sealing ring is made of polyurethane (PU) or filled polytetrafluoroethylene (PTFE), the secondary sealing ring is made of fluororubber (FKM), the guide ring is made of polyoxymethylene (POM), and the dustproof ring is made of polytetrafluoroethylene (PTFE) composite material. The materials work together to balance sealing performance, guiding accuracy, and wear and dust resistance requirements, making it suitable for the harsh working conditions of large-size wellbores with 200°C high temperature, 300kN high pressure, and complex motion, effectively improving the overall reliability and service life of the sealing structure.

[0114] To better illustrate this, the working principle of the present invention is explained below:

[0115] Drilling pressure is transmitted via upper connector 1 to disc spring assembly 7 and rubber sleeve 9, and then via hydraulic chamber 15 and lower connector 4 to the drill bit; torque is transmitted via upper connector 1, housing 2, hydraulic housing 3, and lower connector 4 to the lower drill string. Based on this load transmission path, this invention achieves vibration attenuation through multi-structure collaboration. The core mechanism is a coupling of adaptive axial stiffness adjustment, active hydraulic damping control, and torsional friction energy dissipation. It is also equipped with vibration energy recovery power supply and long-term sealing protection. The specific principle is as follows:

[0116] (1) When the drill string generates axial vibration, the vibration energy acts sequentially on the disc spring assembly 7, the rubber sleeve 9, and the hydraulic damping assembly, forming a layered energy dissipation. The disc spring assembly 7 converts the mechanical energy of axial vibration into elastic potential energy through its own elastic deformation, thus completing the basic damping energy dissipation. When the vibration intensity reaches the set threshold, the shape memory alloy adjusting plate 12 in the shim 8 deforms under vibration excitation, changing the working clearance of the disc spring assembly 7, realizing the adaptive matching of damping stiffness, and adapting to axial vibration of different intensities. The rubber sleeve 9 dissipates vibration energy by relying on its own viscoelasticity and structural deformation. Its cylinder wall opening and spiral cut 91 are matched, which can not only buffer axial impact, but also take into account the dual energy dissipation of axial and torsional vibration, thus improving the overall damping effect.

[0117] (2) The hydraulic damping assembly is the core of axial vibration control. The piston 10 slides back and forth in the hydraulic chamber 15 along the hydraulic sealing seat 11, and the hydraulic medium flows through the hydraulic through hole 16 of the piston 10. The vibration sensor 19 collects vibration signals in real time, processes them, and transmits them to the processor. The processor compares the signals with the built-in large-size wellbore typical formation vibration feature library, identifies the formation type, and predicts the subsequent vibration conditions. Then, it adjusts the opening of the electromagnetic proportional valve 17 in the hydraulic through hole 16 to change the flow area and damping of the hydraulic medium, converting the mechanical energy of vibration into hydraulic energy dissipation. This hydraulic damping adjustment and the stiffness self-adaptation of the disc spring group 7 work together to achieve efficient attenuation of axial vibration. At the same time, the processor can synchronously adjust the control strategy according to the working state of the shape memory alloy adjusting plate 12 to avoid system resonance.

[0118] (3) When the drill string generates torsional stick-slip vibration, the shell 2 and the upper connector 1 are meshed circumferentially through the external spline 6 to transmit torque. The composite spiral groove 18 on the keyway tooth surface and the external spline 6 generate friction, which converts the torsional vibration energy into heat energy for dissipation, thus achieving torsional damping. The rubber sleeve 9 dissipates the torsional vibration energy through the shear deformation of the spiral cut 91, forming a synergistic damping with the composite spiral groove 18. At the same time, the spline clearance does not affect the axial sliding, thus taking into account both torque transmission and axial damping functions.

[0119] (4) The spiral cut 91 of the rubber cylinder 9 is embedded with a piezoelectric ceramic sheet 92. When the rubber cylinder 9 is deformed by vibration, the piezoelectric ceramic sheet 92 converts the mechanical energy of vibration into electrical energy through the positive piezoelectric effect. After rectification, energy storage and voltage stabilization, the electrical energy supplies power to the vibration sensor 19, processor and electromagnetic proportional valve 17, realizing the recovery and utilization of vibration energy. No external power supply is required to meet the needs of long-term underground operation.

[0120] (5) The composite sealing assembly of the hydraulic chamber 15 achieves impurity isolation, motion guidance, high-pressure sealing and high-temperature protection through multi-level structural collaboration, preventing the intrusion of downhole impurities, maintaining the pressure stability of the hydraulic chamber 15, providing a reliable working environment for hydraulic damping adjustment, and ensuring the long-term stable operation of the shock absorber.

[0121] This invention requires no ground signal interaction throughout the entire process. All adjustments are completed autonomously within the shock absorber. Through formation vibration prediction, stiffness self-adaptation, active damping adjustment, and multi-form energy dissipation coupling, it forms a full-condition adaptive vibration attenuation system, which can be adapted to the harsh downhole conditions of large-diameter wells and effectively improve the stability of drilling operations and the service life of the shock absorber.

[0122] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed above through embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A large-size wellbore axial vibration damper, characterized in that, include: The upper connector (1), the housing (2) and the lower connector (4) are provided. The housing (2) is sleeved on the outer wall of the upper connector (1), and a receiving cavity is formed between the inner wall of the housing (2) and the outer wall of the upper connector (1). A disc spring damping assembly is provided in the receiving cavity. A hydraulic damping assembly is connected to the bottom of the housing (2), and the lower connector (4) is connected to the bottom of the hydraulic damping assembly. The hydraulic shock absorber assembly includes a hydraulic housing (3), a piston (10), and a hydraulic sealing seat (11). The hydraulic housing (3) is fitted onto the bottom of the housing (2). The hydraulic sealing seat (11) is connected to the bottom of the hydraulic housing (3) and has a hydraulic cavity (15) inside. The piston (10) passes through the hydraulic sealing seat (11) and is slidably disposed in the hydraulic cavity (15). The piston (10) has a hydraulic through hole (16), and an electromagnetic proportional valve (17) is connected in the hydraulic through hole (16).

2. The shock absorber according to claim 1, characterized in that, The disc spring damping assembly includes a disc spring group (7), with a pad (8) abutting the top and bottom of the disc spring group (7). The pad (8) has an installation groove, and a memory alloy adjustment piece (12) is provided in the installation groove.

3. The shock absorber according to claim 2, characterized in that, A rubber cylinder (9) abuts between the disc spring assembly (7) and the hydraulic housing (3). The wall of the rubber cylinder (9) is evenly distributed with through holes, and the wall of the rubber cylinder (9) is provided with a spiral cut (91).

4. The shock absorber according to claim 3, characterized in that, It also includes an adjustment component, which includes a vibration sensor (19) and a processor. The vibration sensor (19) is electrically connected to the processor, and the processor is electrically connected to the electromagnetic proportional valve (17). Both the vibration sensor (19) and the processor are disposed inside the piston (10).

5. The shock absorber according to claim 4, characterized in that, The inner wall of the housing (2) is provided with a keyway, and the outer wall of the upper connector (1) is provided with an external spline (6) that engages with the keyway, so that the housing (2) and the upper connector (1) are circumferentially fixedly connected.

6. The shock absorber according to claim 5, characterized in that, The spiral cut (91) is evenly distributed with piezoelectric ceramic sheets (92). The piezoelectric ceramic sheets (92) are electrically connected to the vibration sensor and the processor. The piezoelectric ceramic sheets (92) are used to convert vibration energy into electrical energy to power the vibration sensor and the processor.

7. The shock absorber according to claim 6, characterized in that, The keyway has a spiral groove on its tooth surface, and the spiral groove is filled with wear-resistant material. The spiral groove and the wear-resistant material together form a composite spiral groove (18). The composite spiral groove (18) dissipates torsional vibration energy through the friction of the relative rotation of the spline mating surfaces, thereby achieving torsional vibration attenuation.

8. The shock absorber according to claim 7, characterized in that, Sealing grooves are provided at the connection between the hydraulic housing (3) and the upper connector (1) and at the connection between the hydraulic housing (3) and the hydraulic sealing seat (11). A composite sealing assembly is provided in the sealing groove. The composite sealing assembly includes a main sealing ring, a secondary sealing ring, a guide ring and a dustproof ring connected in sequence.

9. The shock absorber according to claim 4, characterized in that, The processor has a built-in database of typical formation vibration characteristics of large-size wellbores. The processor is configured to compare and analyze the axial vibration signal collected by the vibration sensor (19) with the database of typical formation vibration characteristics of large-size wellbores, determine the vibration mode of the next stage of drilling operation, and output control commands to adjust the valve opening of the electromagnetic proportional valve (17) according to the prediction results, so as to adjust the hydraulic damping.

10. The shock absorber according to claim 6, characterized in that, The piezoelectric ceramic sheet (92) has an arc-shaped sheet structure with a curvature that matches the spiral cut (91). The surface of the piezoelectric ceramic sheet (92) is nickel-plated to form a bottom protective layer. A polytetrafluoroethylene coating is also applied to the outside of the bottom protective layer to form a top protective layer.

Images