A tandem two-stage shock absorber for oil drilling

Abstract

The application relates to a series double-stage shock absorber for oil drilling, which comprises a shell, a fluid damping module, an inertial vibration absorption module, a pressure compensator system and a heat dissipation and sealing system arranged in the shell, the fluid damping module and the inertial vibration absorption module are axially connected in series to form a series double-stage shock absorbing structure, the fluid damping module is arranged in a fluid damping chamber at the lower part of the shell, the inertial vibration absorption module is arranged in an inertial vibration absorption chamber at the upper part of the shell, and the pressure compensator system is arranged between the fluid damping module and the inertial vibration absorption module; the fluid damping module comprises rectangular damping discs, a transition flow channel and damping liquid, the rectangular damping discs are uniformly arranged outside the transition flow channel, and the rectangular damping discs are provided with damping holes and damping rib plates; heat dissipation fins are uniformly arranged at the lower part of the shell. The series double-stage shock absorbing structure is adopted, large energy low-frequency impact is consumed through the fluid damping chamber, high-frequency vibration is filtered through the inertial vibration absorption chamber, and wide-band and high-efficiency multidimensional vibration suppression is realized.

Description

Technical Field

[0001] This invention relates to the field of downhole tools technology for oil and gas drilling, specifically a high-performance downhole shock absorber for suppressing axial and torsional vibrations of the drill string. Background Technology

[0002] In the field of oil drilling, the complex vibrations experienced by the downhole drill string system are a key challenge restricting drilling efficiency and safety. Traditional shock absorbers mostly employ pure spring structures or hydraulic damping structures based on a single-stage damping principle. Their natural frequency range is narrow, making it difficult to effectively cover the wide frequency spectrum of energy generated during drilling, ranging from low-frequency high-energy impacts (such as stick-slip vibrations) to high-frequency residual vibrations (such as drill bit bounce). Furthermore, existing pressure compensation systems are typically single-path passive designs, exhibiting delayed response and prone to system failure when critical components malfunction, making it difficult to reliably maintain a seal during severe downhole pressure fluctuations. Their outer shells are often smooth cylindrical surfaces with limited heat dissipation area, resulting in low efficiency in heat dissipation through drilling fluid convection. Internal heat accumulation can easily lead to material aging and performance degradation. Simultaneously, existing technologies generally neglect targeted treatment of high-frequency vibrations or rely solely on a single damping mechanism, resulting in the frequency band limitation of single-stage damping. Summary of the Invention

[0003] The purpose of this invention is to provide a series-type two-stage shock absorber for oil drilling. This series-type two-stage shock absorber for oil drilling solves the problems of material aging and performance degradation caused by poor heat dissipation in existing downhole shock absorbers, as well as the frequency band limitation problem of single-stage shock absorbers.

[0004] The technical solution adopted by this invention to solve its technical problem is as follows: This series-type two-stage shock absorber for oil drilling includes a shell, inside which a fluid damping module, an inertial vibration absorption module, a pressure compensator system, and a heat dissipation and sealing system are arranged. The fluid damping module and the inertial vibration absorption module are axially connected in series to form a series-type two-stage shock absorption structure. The fluid damping module is located in the fluid damping chamber at the bottom of the shell, and the inertial vibration absorption module is located in the inertial vibration absorption chamber at the top of the shell. A pressure compensator system is arranged between the fluid damping module and the inertial vibration absorption module. The fluid damping module includes a rectangular damping disk, a transition channel, and damping fluid. The rectangular damping disk is evenly arranged outside the transition channel. The rectangular damping disk is provided with damping holes and damping ribs. Bearings are arranged at both ends of the transition channel, and the two ends of the transition channel are connected to the drilling fluid channel through the bearings. The damping fluid is filled in the fluid damping chamber; the inertial vibration absorption module consists of an upper inertial mass block group and a lower inertial mass block group symmetrically installed outside the transition sleeve. The outer wall of the transition sleeve is provided with a high-performance elastic rubber body. The upper inertial mass block group includes an upper inertial mass block, an upper inertial mass block guide sleeve, a second limiting spring, and an upper inertial mass block limiting baffle. The upper inertial mass block limiting baffle is fixedly connected to the lower port of the upper inertial mass block guide sleeve. The upper inertial mass block and the second limiting spring are set outside the transition sleeve. When the upper inertial mass block moves upward, it compresses the second limiting spring. An intermediate inertial mass block guide sleeve is set between the upper inertial mass block group and the lower inertial mass block group. The transition sleeve is fitted outside the drilling fluid flow channel. The upper port of the upper inertial mass block guide sleeve is connected to a locking cap. Heat dissipation fins are evenly arranged on the lower part of the outer shell.

[0005] The above scheme includes a lower inertial mass block assembly comprising a lower inertial mass block, a lower inertial mass block guide sleeve, a first limiting spring, and a lower inertial mass block limiting baffle. The lower inertial mass block limiting baffle is fixedly connected to the lower end of the lower inertial mass block guide sleeve. The lower inertial mass block and the first limiting spring are disposed outside the transition sleeve. When the lower inertial mass block moves downward, it compresses the first limiting spring. When high-frequency vibration is transmitted through the outer shell, each inertial mass block generates shear motion opposite to the vibration direction due to inertial lag. Its kinetic energy is converted into heat energy dissipation through the internal friction of the high-performance rubber body. The guide sleeves of each inertial mass block ensure the accurate movement trajectory of the corresponding inertial mass block and prevent skew collisions. The limiting spring, through its pre-compression force, sets a safe movement boundary for the corresponding inertial mass block, ensuring that the inertial mass block always moves within the elastic range.

[0006] The pressure compensator system described above includes a pressure compensator module, a pressure balancing diaphragm, a pressure compensating oil circuit, and a pressure compensating end cap. The pressure compensating end cap is placed on an annular retaining ring on the outer shell. A sealing groove is located at the junction of the pressure compensating end cap and the drilling fluid flow channel. A pressure compensating oil circuit, T-shaped, is installed inside the pressure compensating end cap, with oil outlets at both ends. A pressure balancing diaphragm is inserted into each oil outlet, and a hollow pressure cap is screwed tightly onto the oil outlet. A side hole is provided at the junction of the pressure compensating end cap and the outer shell. The pressure compensator module is a cylindrical structure consisting of a pressure compensator interface and a cylindrical body integrated together. The inlet has an external thread, and the pressure compensator interface has an oil passage connected to the pressure compensation oil circuit. The inlet and outlet ends of the pressure compensation oil bladder inside the cylinder are embedded with a threaded metal skeleton. The end of the pressure compensation oil bladder is screwed into the stepped countersunk hole of the pressure compensator interface through a clamping screw, which axially presses the metal skeleton onto the step, realizing a rigid connection and reliable sealing between the pressure compensation oil bladder and the internal oil passage of the pressure compensator module. The inlet end of the compensation oil bladder is a process oil injection hole, which is sealed by a high-pressure screw plug with a sealing ring. The pressure compensator module passes through the side hole on the outer shell and is threadedly connected to the pressure compensation end cap. The solid pressure cap is screwed onto the side hole.

[0007] The heat dissipation and sealing system in the above scheme includes the heat dissipation fins, the pressure compensation end cap sealing ring, and the lower end cap sealing ring. The pressure compensation end cap sealing ring is located in the sealing groove of the pressure compensation end cap. The lower end cap is located at the lower port of the outer shell. The connection between the lower end cap and the drilling fluid flow channel is located in the sealing groove. The lower end cap sealing ring is located in the sealing groove. The lower end cap is connected to the lower connector.

[0008] In the above scheme, both the upper inertial mass block and the lower inertial mass block are cylindrical bodies with an outer edge at one end. Beneficial effects

[0009] 1. This invention adopts a series-type dual-stage vibration reduction architecture. It consumes high-energy low-frequency impacts through a fluid damping chamber and filters high-frequency vibrations through an inertial vibration absorption chamber, thereby achieving wide-bandwidth and high-efficiency multi-dimensional vibration suppression. It avoids mutual constraints between different damping mechanisms in the same space and achieves superimposed performance gains.

[0010] 2. This invention adopts a modular dual-redundant pressure compensation system, which effectively avoids the risk of single-point failure and greatly improves the reliability of the tool during long-term downhole operation. The compensator itself can be designed as a quick-replaceable module, making maintenance convenient.

[0011] 3. This invention integrates heat dissipation fins into the outer shell, effectively controlling the temperature rise generated during damping operation and ensuring material performance and seal life. With no moving parts, it utilizes purely physical heat dissipation, resulting in a simple structure that will never fail. It maintains the stability of the damping fluid viscosity, thus ensuring long-term consistency in shock absorption performance. The fins significantly increase the contact area with the circulating drilling fluid, utilizing forced convection generated by drill string rotation to efficiently remove internal heat, keeping the tool operating within a safe temperature range.

[0012] 4. The inertial vibration-absorbing chamber is specially optimized and tuned for high-frequency vibration, the fluid damping in the lower chamber resolves severe low-frequency impacts, and the integrated heat dissipation system controls the temperature rise of the tool, providing a stable temperature environment for the instrument. This significantly reduces the failure rate of downhole measurement while drilling (MWD) / logging while drilling (LWD) instruments and ensures the continuity and accuracy of data transmission.

[0013] 5. This invention introduces an inertial vibration absorption module composed of an inertial mass block and a vibration-absorbing rubber body, which realizes targeted absorption and efficient filtering of high-frequency residual vibration of the drill string, and significantly improves the wideband suppression capability of the shock absorber.

[0014] 6. This invention first employs a series-connected dual-stage vibration reduction architecture, axially connecting the fluid damping module and the inertial vibration absorption module. Functional decoupling optimizes the handling of low-frequency high-energy vibrations and high-frequency residual vibrations, overcoming the frequency band limitations of single-stage vibration reduction. Second, a modular dual-redundant pressure compensation system is designed, employing parallel oil circuits and independent chambers working in tandem. This system can sense and dynamically balance the internal and external pressures of the tool in real time, significantly reducing the working pressure difference of the seals and improving system-level reliability. Third, axial heat dissipation fins are integrated into the outer shell, greatly increasing the heat exchange area. Induced drilling fluid turbulence enhances heat dissipation, effectively controlling the internal working temperature. Finally, the inertial vibration absorption module chamber is specially tuned. By precisely matching the stiffness of the inertial mass block and the vibration-absorbing rubber body, optimal phase cancellation (anti-resonance) effect is generated within the target high-frequency band, achieving targeted absorption of high-frequency vibrations. These innovative designs together constitute a highly reliable, wide-bandwidth damping downhole shock absorber, providing a better technical option for deep well drilling operations; the present invention is a series-type two-stage downhole shock absorber with reasonable structure, good damping effect, high reliability and long service life. Attached Figure Description Figure 1 This is a cross-sectional view of the present invention; Figure 2 This is a schematic diagram of the rectangular damping disk in this invention; Figure 3 This is a schematic diagram of the pressure compensator system in this invention; Figure 4 This is a schematic diagram showing the relationship between the heat dissipation fins and the outer casing in this invention; Figure 5This is a schematic diagram of the transition sleeve and its partially enlarged structure in this invention; Figure 6 This is a schematic diagram of the pressure compensator module in this invention.

[0015] Figure 1 In the middle section: 1. Outer shell, 2. Locking gland, 3. Lower connector, 4. Upper inertial mass block, 5. Lower inertial mass block, 6. Upper inertial mass block limiting baffle, 7. Upper inertial mass block guide sleeve, 8. First limiting spring, 9. Second limiting spring, 10. Pressure compensation end cap, 11. Fluid damping chamber, 12. High-performance elastic rubber body, 13. Drilling fluid flow channel, 14. Lower end cap; 15. Transition casing; 16. Rectangular damping disc, 17. Damping hole, 18. Damping rib, 19. Positioning groove, 20. Bearing; 21. Pressure compensation end cap sealing ring, 22. Diaphragm, 23. Hollow gland, 24. Pressure compensation oil circuit, 25. Pressure compensator interface, 26. Process oil injection hole, 27. Pressure compensation oil bladder, 28. Solid gland, 29. Pressure compensator module; 30. Heat dissipation fins. Detailed Implementation Combination Figures 1-6 As shown, this series-connected two-stage vibration damper for oil drilling employs a layout where an inertial damping chamber and a fluid damping chamber are connected in series. Vibration energy is first dissipated by the lower fluid damping chamber 11, and then filtered by the upper inertial damping chamber. This graded processing mode specifically covers a wide frequency spectrum of energy, from low-frequency impacts to high-frequency vibrations. This series-connected two-stage vibration damper for oil drilling includes a housing 1, within which are installed a fluid damping module, an inertial damping module, a pressure compensator system, and a heat dissipation and sealing system. The fluid damping module and the inertial damping module are axially connected in series to form a series-connected two-stage vibration damping architecture. The fluid damping module is located in the lower fluid damping chamber 11 of the housing 1, and the inertial damping module is located in the upper inertial damping chamber of the housing 1. A pressure compensator system is installed between the fluid damping module and the inertial damping module. The outer casing 1 is equipped with API standard threaded connectors at both the top and bottom ends; the interior of the outer casing is divided into an inertial vibration absorption chamber and a fluid damping chamber 11 arranged at the top and bottom through an isolation structure, and heat dissipation fins are evenly arranged at the bottom of the outer casing.

[0016] The inertial vibration absorption module includes an inertial mass block connected to a high-performance rubber elastomer and a drilling fluid flow channel shell. The module cavity is a sealed structure, comprising an upper inertial mass block 4, a lower inertial mass block 5, a high-performance rubber elastomer 12, an inertial mass block guide sleeve, a limiting spring, and an inertial mass block limiting baffle. The inertial mass block is elastically connected to the transition sleeve via the high-performance rubber elastomer 12. When high-frequency vibration is transmitted through the shell 1, the inertial mass block, due to inertial hysteresis, generates shear motion opposite to the vibration direction. Its kinetic energy is converted into heat energy dissipation through the internal friction of the high-performance rubber elastomer 12. The inertial mass block guide sleeve ensures the precise trajectory of the inertial mass block, preventing skew and collision. The limiting spring, through its preload, sets a safe movement boundary for the inertial mass block, ensuring it always moves within the designed elastic range. The dual inertial mass block design, with its precisely proportioned mass, allows tuning to different natural frequencies, thereby expanding the bandwidth of high-frequency vibration suppression and avoiding resonance failure that might occur with a single mass block at a specific frequency. The inertial vibration absorption module is detailed below: The inertial vibration absorption module consists of an upper inertial mass block group 4 and a lower inertial mass block group 5 symmetrically installed outside a transition sleeve. A high-performance elastic rubber body 12 is provided on the outer wall of the transition sleeve 15. The upper inertial mass block group includes an upper inertial mass block 4, an upper inertial mass block guide sleeve 7, a second limiting spring 9, and an upper inertial mass block limiting baffle 6. The upper inertial mass block limiting baffle 6 is fixedly connected to the lower end of the upper inertial mass block guide sleeve 7. The upper inertial mass block 4 and the second limiting spring 9 are located outside the transition sleeve 15. When the upper inertial mass block 4 moves upward, it compresses the second limiting spring 9, thus absorbing vibration. An intermediate inertial mass block guide sleeve is provided between the mass block group and the lower inertial mass block group. The transition sleeve 15 is fitted outside the drilling fluid flow channel 13. The upper end of the upper inertial mass block guide sleeve 7 is connected to a locking cap. The lower inertial mass block group includes a lower inertial mass block 5, a lower inertial mass block guide sleeve, a first limiting spring 8, and a lower inertial mass block limiting baffle. The lower inertial mass block limiting baffle is fixedly connected to the lower end of the lower inertial mass block guide sleeve. The lower inertial mass block and the first limiting spring 8 are located outside the transition sleeve 15. When the lower inertial mass block moves downward, it compresses the first limiting spring 8. Both the upper inertial mass block 4 and the lower inertial mass block 5 are cylindrical bodies with an outer edge at one end.

[0017] The pressure compensator system includes a pressure compensator module, a pressure balancing diaphragm, a pressure compensating oil passage 24, and a pressure compensating end cap 10. The pressure compensating end cap 10 is placed on an annular retaining ring on the outer casing 1. A sealing groove is provided at the junction of the pressure compensating end cap 10 and the drilling fluid flow channel 13. The pressure compensating oil passage 24 is T-shaped, with oil outlets at both ends. A pressure balancing diaphragm is placed in each oil outlet. A hollow pressure cap 23 is screwed onto the oil outlet. A side hole is provided at the junction of the pressure compensation end cap 10 and the outer shell 1. The pressure compensator module is a cylindrical body integrally formed by the pressure compensator interface 25 and the cylinder. The pressure compensator interface 25 has external threads and an oil passage connected to the pressure compensation oil circuit 24. Threaded metal skeletons are embedded in the inlet and outlet ends of the pressure compensation oil bladder 27 inside the cylinder. The end of the pressure compensation oil bladder 27 is screwed into the stepped countersunk hole of the pressure compensator interface 25 through a clamping screw, axially pressing the metal skeleton onto the step. When the tool enters the high-pressure zone, the drilling fluid pressure in the wellbore is transmitted to the pressure balance diaphragm through the tool shell. The diaphragm 22 is driven by the external high pressure and undergoes elastic deformation towards the inside of the tool. The deformation of the diaphragm 22 compresses the adjacent oil chamber, causing the compensating oil to flow through the pressure compensation oil circuit 24 to the pressure compensation oil bladder 27. The oil enters the pressure compensation oil bladder 27, driving it to expand to increase the internal volume of the tool, thereby counteracting the compression of the sealing system by the external high pressure. Conversely, when the tool is pulled up to a low-pressure section, the external pressure decreases, the diaphragm rebounds, and the oil bladder contracts, maintaining the internal and external pressure difference close to zero. Furthermore, a dual-pressure compensator design is employed, forming a "main-backup" system. If the main compensator fails unexpectedly, the backup compensator can take over, greatly reducing the risk of the entire tool failing due to a single point of failure, making it particularly suitable for long-term downhole operations. In this invention, the oil bladder is the pressure compensation oil bladder 27, and the diaphragm 22 is the pressure balancing diaphragm.

[0018] The fluid damping module includes a rectangular damping disc 16, a bearing 20, a damping hole 17, a damping rib 18, a positioning groove 19, and a high-performance damping fluid. When the vibration of the drill string is transmitted from the drill bit and enters the tool through the lower connector, the fluid damping chamber 11 is activated first. The rotation of the drill string drives the bearing 20 to rotate, and the rectangular damping disc 16 fixed on it rotates within the chamber filled with high-performance damping fluid. The specially designed damping hole 17 on the disc greatly disturbs the fluid, generating strong viscous resistance, directly converting the mechanical energy of the high-energy low-frequency impact into the thermal energy of the damping fluid. The damping rib 18 significantly improves the bending and torsional stiffness of the damping disc by increasing the moment of inertia of the cross section, preventing plastic deformation or resonance failure, and ensuring that the damping clearance remains constant. The bearing 20 ensures smooth and precise rotation of the damping plate during this process, while the positioning groove 19 maintains the stability of the entire rotation system. When the drill string suddenly jams, the lower chamber achieves a soft landing of the impact energy through rapid balancing by the pressure compensation system, energy absorption by the compression of the damping fluid, and coordinated restraint by structural components. This design prevents internal overload failure of the tool and ensures the overall safety of the drill string.

[0019] The heat dissipation and sealing system includes heat dissipation fins 30, a pressure compensation end cap sealing ring 21, and a lower end cap sealing ring. The pressure compensation end cap sealing ring is located in the sealing groove of the pressure compensation end cap; the lower end cap is located at the lower port of the outer shell, and the connection between the lower end cap and the drilling fluid flow channel is located in the sealing groove, where the lower end cap sealing ring is located, and the lower end cap connects to the lower connector. The heat dissipation fins increase the heat dissipation area to 2-3 times the original size, and the grooves between the fins guide the drilling fluid to form turbulence, enhancing the flushing effect and continuously carrying away heat from the tool surface. The sealing ring uses a high-performance O-ring seal, providing a primary sealing barrier at the tool connection to prevent high-pressure damping fluid from leaking into the lower chamber or intruding into the upper chamber.

[0020] like Figure 1As shown, the assembled bearing 20 and rectangular damping disc 16 are vertically lifted and placed on the fine drilling fluid channel 13 in the lower chamber. Then, they are vertically placed into the outer shell 1 and aligned with the lower end cap 14. High-performance damping fluid is slowly injected into the fluid damping chamber 11. Utilizing the incompressibility of the liquid in the full-fluid state, the vibration impact is instantly converted into a strong shear force between the damping disc 16 and the damping fluid, achieving immediate dissipation of high-energy, low-frequency impact. The pressure compensation end cap 10 is then lowered onto the annular retaining ring in the middle of the outer shell 1, and the end cap is rotated to align with the pre-installed pressure compensator module 25 on the outer shell 1. The pressure compensator modules 29 are then screwed into both sides. The lower inertial mass block guide sleeve 7 is then inserted. A separate thin-walled transition sleeve 15 is provided, the inner diameter of which is slightly larger than the outer diameter of the drilling fluid flow channel 13. A first limiting spring 8 is sleeved on the lower outer side of the transition sleeve 15. The integrated assembly of the lower inertial mass block 5, the lower inertial mass block limiting baffle, the middle inertial mass block guide sleeve, the upper inertial mass block limiting baffle 6, and the upper inertial mass block 5 is coaxially sleeved into the transition sleeve 15, so that the high-performance elastic rubber body 12 is firmly connected to the outer peripheral surface of the transition sleeve 15. Then, the second limiting spring 9 is installed, and the limiting baffle is axially locked by inserting an elastic retaining ring into the pre-set annular groove on the transition sleeve 15, thereby completing the overall inertial vibration absorption sub-module including the spring, mass block, and limiting baffle. Pre-assembly; finally, perform the upper chamber assembly. Stand the drilling fluid channel 13, which has been assembled with the lower chamber and pressure compensation end cap 10, upright. Align the pre-assembled inertial vibration absorber module coaxially with the upper opening of the drilling fluid channel 13. Since the inner diameter of the transition sleeve 15 is slightly larger than the outer diameter of the drilling fluid channel 13, the entire inertial vibration absorber module smoothly slides into the drilling fluid channel 13 along the axial direction until the bottom end of the transition sleeve touches the positioning step on the pressure compensation end cap 10. Install the locking cap 2 at the top of the drilling fluid channel 13. Tighten the locking cap 2 so that its bottom surface presses against the upper end surface of the transition sleeve, and firmly lock the transition sleeve and the drilling fluid channel 13 into one, completing the final assembly of the tool.

[0021] like Figure 4 As shown, heat dissipation fins 30 are machined on the outer surface of the outer shell 1. These fins are integrally formed with the outer shell 1. Heat generated inside the tool is conducted to the heat dissipation fins 30 on the outer surface through the outer shell 1. As the drill string rotates and the drilling fluid circulates, the drilling fluid flowing over the fin surface continuously carries away the heat, achieving continuous cooling of the tool. The connection between the lower end cover 14 and the inner wall of the outer shell 1 is sealed by a lower end cover 14 sealing ring. The material of the lower end cover 14 sealing ring is selected according to the operating temperature, such as fluororubber. After the pressure compensation system balances the internal and external pressures, the static seal only needs to prevent leakage, resulting in extremely high reliability. Figure 2As shown, the upper and lower ends of the fine drilling fluid flow channel (i.e., the transition flow channel) in the lower chamber are connected by threads for easy disassembly, facilitating the installation of the rectangular damping disc 16. The bearing 20 and the positioning groove 19 are installed using a heating fit method, ensuring a tight fit between the outer ring of the bearing 20 and its end face with the positioning groove 19. The damping disc and damping rib 18 are preferably manufactured using an integral forging process, avoiding stress concentration and fatigue weak points that may result from welding or bolting connections, ensuring structural integrity and high reliability. The damping hole 17 is formed using laser processing to ensure a smooth hole wall.

[0022] like Figure 3 As shown, the diaphragm anti-detachment installation is first performed. The surface of the pressure balancing diaphragm 22 is checked for smoothness and absence of scratches. The pressure balancing diaphragm 22 is then smoothly placed above and below the oil outlet of the pressure compensation end cap 10. The hollow pressure cap 23 is then screwed in to ensure the diaphragm will not detach due to pressure. The pressure compensator module 29 is screwed into the side hole of the end cap 10, while leaving a solid pressure cap channel 28. The connection between the pressure compensation oil bladder 27 and the internal flow channel of the module 26 adopts an anti-pull-out flange clamping structure. A threaded metal skeleton is embedded in the inlet and outlet ends of the pressure compensation oil bladder 27 to prevent the rubber body from being pulled out. The end of the pressure compensation oil bladder 27 is screwed into the stepped countersunk hole through a clamping screw, axially and firmly pressing the metal skeleton onto the step, achieving a rigid connection and reliable seal between the pressure compensation oil bladder 27 and the internal flow channel of the pressure compensation module 29, thereby completely resisting connection failure caused by downhole high-pressure impact and severe vibration. Next, the entire closed system is evacuated to a high negative pressure state. Then, compensation oil is sequentially passed through the process oil injection port 26, the oil passage of the pressure compensator interface, and the pressure compensation oil circuit 24, ensuring the oil fills all dead zones and the oil bladder 25 expands naturally, guaranteeing no residual air in the system. Finally, a high-pressure plug with a sealing ring is screwed into the process oil injection port 26 to achieve a leak-free and cavitation-free full-oil seal assembly. Finally, the solid gland 28 is screwed in to achieve a completely sealed state, realizing a leak-free and cavitation-free full-oil seal assembly.

[0023] The working process of this invention is described as follows: When complex vibrations generated by the drill bit breaking rock (such as axial skipping and torsional stick-slip) are transmitted to the tool through the lower connector 3, the working process officially begins: First, the vibration energy enters the fluid damping chamber 11, where the high-performance damping fluid absorbs most of the low-frequency vibrations. The rotation of the drill string drives the rectangular damping disk 16, which is fixed to it, to rotate within the chamber filled with high-performance damping fluid. The full fluid state ensures a constant damping fluid density, making the viscous resistance generated by the damping orifice 17 stable and predictable. When the damping fluid flows through the damping orifice 17, it generates strong viscous resistance, converting a large amount of mechanical energy into heat energy. The damping rib 18 enhances the stiffness of the damping disk. This process consumes most of the low-frequency impact energy. When the drill string suddenly stops, the rectangular damping disk 16 still tends to continue rotating due to its own inertia. This results in a very strong instantaneous shearing action between the damping orifice 17 and the surrounding damping fluid, rapidly converting the huge inertial kinetic energy into heat energy, causing the damping fluid temperature to rise instantaneously, thus preventing stress from being directly transmitted to the upper drill string and downhole instruments.

[0024] Subsequently, the residual vibration after the first stage of treatment is transmitted to the inertial vibration absorption chamber through the outer shell 1. This is the core of handling high-frequency vibration. Under the elastic support of the high-performance elastic rubber body 12, the upper inertial mass block 4 and the lower inertial mass block 5 undergo shear deformation due to inertial lag behind the movement of the outer shell 1, further dissipating the energy of the high-frequency vibration. The inertial mass block guide sleeve ensures the stability of the mass block's movement, while the first limit spring 8 and the second limit spring 9 prevent excessive displacement under extreme working conditions, which could lead to tearing of the high-performance elastic rubber body 12. Throughout the entire operation, the pressure compensation system is crucial. The pressure balancing diaphragm 22 senses changes in downhole pressure in real time. When the external pressure increases, it acts on the outer shell 1. The external high pressure is transmitted to the pressure balancing diaphragm 22, and the diaphragm is driven by the radial pressure difference to deform inward toward the tool center (radially inward), squeezing adjacent oil chambers; when the external pressure decreases, the diaphragm rebounds toward the tool outer wall (radially outward) under the drive of the internal micro-pressure. Simultaneously, when the diaphragm flexes radially, a slight axial follow-up tilt occurs at the edge of the pressure compensation end cap 10. The hollow gland 25 reserved inside the end cap allows this axial follow-up, thus preventing the diaphragm edge from tearing due to stress concentration. This achieves real-time, highly sensitive follow-up capture of external pressure changes. The oil is squeezed into the pressure compensation oil passage 24 and flows to the pressure compensation oil bladder 27. The oil bladder expands, occupying the space inside the tool, causing the internal pressure to rise until it cancels out the external pressure, ensuring that the fluid damping chamber 11 and the upper inertial mass block 4 and lower inertial mass block 5 always operate under a low pressure difference, thereby greatly improving the reliability of the tool. At the same time, the heat dissipation system continues to operate. The heat generated by the operation of the fluid damping chamber 11 is conducted through the outer shell 1 to the heat dissipation fins 30 on the outer wall, and is finally carried away by the circulating drilling fluid, maintaining a stable internal temperature of the tool and preventing performance degradation. Finally, the stable load after two-stage damping is output to the upper drill string through the locking gland 2. This invention achieves effective management of complex downhole vibrations through the precise coordination of the aforementioned components, significantly improving the efficiency and safety of drilling operations.

Claims

1. A tandem dual-stage shock absorber for oil drilling, characterized by: This tandem two-stage shock absorber for oil drilling includes a housing, within which are housed a fluid damping module, an inertial vibration absorption module, a pressure compensator system, and a heat dissipation and sealing system. The fluid damping module and the inertial vibration absorption module are axially connected in series to form a tandem two-stage shock absorber architecture. The fluid damping module is located in the fluid damping chamber at the bottom of the housing, and the inertial vibration absorption module is located in the inertial vibration absorption chamber at the top of the housing. A pressure compensator system is installed between the fluid damping module and the inertial vibration absorption module. The fluid damping module includes a rectangular damping disc, a transition channel, and damping fluid. The rectangular damping disc is evenly distributed outside the transition channel and has damping holes and damping ribs. Bearings are installed at both ends of the transition channel, connecting it to the drilling fluid channel via the bearings. The damping fluid is filled in the fluid damping disc. In the nitrile chamber, the inertial vibration absorption module consists of an upper inertial mass block group and a lower inertial mass block group symmetrically installed outside the transition sleeve. The outer wall of the transition sleeve is provided with a high-performance elastic rubber body. The upper inertial mass block group includes an upper inertial mass block, an upper inertial mass block guide sleeve, a second limiting spring, and an upper inertial mass block limiting baffle. The upper inertial mass block limiting baffle is fixedly connected to the lower port of the upper inertial mass block guide sleeve. The upper inertial mass block and the second limiting spring are set outside the transition sleeve. When the upper inertial mass block moves upward, it compresses the second limiting spring. An intermediate inertial mass block guide sleeve is set between the upper inertial mass block group and the lower inertial mass block group. The transition sleeve is fitted outside the drilling fluid flow channel. The upper port of the upper inertial mass block guide sleeve is connected to a locking cap. Heat dissipation fins are evenly arranged on the lower part of the outer shell.

2. The tandem dual-stage shock absorber for oil drilling according to claim 1, characterized in that: The lower inertial mass block assembly includes a lower inertial mass block, a lower inertial mass block guide sleeve, a first limiting spring, and a lower inertial mass block limiting baffle. The lower inertial mass block limiting baffle is fixedly connected to the lower end of the lower inertial mass block guide sleeve. The lower inertial mass block and the first limiting spring are disposed outside the transition sleeve. When the lower inertial mass block moves downward, it compresses the first limiting spring. When high-frequency vibration is transmitted through the outer shell, each inertial mass block generates shear motion opposite to the vibration direction due to inertial lag. Its kinetic energy is converted into heat energy dissipation through the internal friction of the high-performance rubber body. The guide sleeve of each inertial mass block ensures the accurate movement trajectory of the corresponding inertial mass block and prevents skew collision. The limiting spring, through its pre-compression force, sets a safe movement boundary for the corresponding inertial mass block, ensuring that the inertial mass block always moves within the elastic range.

3. The tandem dual-stage shock absorber for oil drilling according to claim 2, characterized in that: The pressure compensator system includes a pressure compensator module, a pressure balancing diaphragm, a pressure compensating oil circuit, and a pressure compensating end cap. The pressure compensating end cap is placed on an annular retaining ring on the outer shell. A sealing groove is provided at the junction of the pressure compensating end cap and the drilling fluid flow channel. A pressure compensating oil circuit is provided inside the pressure compensating end cap; the pressure compensating oil circuit is T-shaped, with oil outlets at both the upper and lower ends. A pressure balancing diaphragm is placed in each oil outlet, and a hollow pressure cap is screwed tightly onto the oil outlet. A side hole is provided at the junction of the pressure compensating end cap and the outer shell. The pressure compensator module is a cylindrical body integrally formed by the pressure compensator interface and the cylinder. The pressure compensator interface has… It has external threads, and the pressure compensator interface has an oil passage connected to the pressure compensation oil circuit. The inlet and outlet ends of the pressure compensation oil bladder inside the cylinder are embedded with a threaded metal skeleton. The end of the pressure compensation oil bladder is screwed into the stepped countersunk hole of the pressure compensator interface through a clamping screw, which axially presses the metal skeleton onto the step, realizing a rigid connection and reliable sealing between the pressure compensation oil bladder and the internal oil passage of the pressure compensator module. The inlet end of the compensation oil bladder is a process oil injection hole, which is sealed by a high-pressure screw plug with a sealing ring. The pressure compensator module passes through the side hole on the outer shell and is threadedly connected to the pressure compensation end cap. The solid pressure cap is screwed onto the side hole.

4. The tandem dual-stage shock absorber for oil drilling according to claim 3, characterized in that: The heat dissipation and sealing system includes the heat dissipation fins, the pressure compensation end cap sealing ring, and the lower end cap sealing ring. The pressure compensation end cap sealing ring is located in the sealing groove of the pressure compensation end cap. The lower end cap is located at the lower port of the outer shell. The lower end cap is located in the sealing groove at the junction with the drilling fluid flow channel. The lower end cap sealing ring is located in the sealing groove. The lower end cap is connected to the lower connector.

5. The tandem dual-stage shock absorber for oil drilling according to claim 4, characterized in that: Both the upper inertial mass block and the lower inertial mass block are cylindrical bodies with an outer edge at one end.

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