A hanging device for a complex well condition sealed coring tool

Abstract

The utility model discloses a kind of for complex well condition sealed coring tool's suspension device, it is related to drilling coring tool technical field, the suspension device is used to be connected with the upper joint of outer tube and inner tube, hollow cavity that is equipped with in suspension device is connected with ground atmosphere inner tube cavity, one-way valve piece is arranged in hollow cavity;One-way valve piece is set as when inner tube cavity is caused by sealing liquid release obstruction and leads to pressure increase, automatically open, sealing liquid is released upward in conduction, to reduce inner tube cavity pressure, so that core enters smoothly.The utility model is by being equipped with the one-way valve piece that can automatically respond pressure change in the hollow cavity of suspension device, realize reverse conduction and pressure automatic release when sealing liquid release obstruction, to reach in suspension device Construction fluid passage and pressure regulating function, prevent sealing liquid obstruction when inner tube cavity pressure accumulation forms liquid lock coring, the purpose of improving soft broken stratum coring success rate.

Description

Technical Field

[0001] This utility model relates to the field of drilling coring tools, specifically to a suspension device for a closed coring tool in complex well conditions. Background Technology

[0002] Closed-loop coring is a crucial method for obtaining original core samples from deep formations, especially in complex conditions such as highly deviated wells, small-diameter wells, and soft, fractured formations, where stringent requirements for core fidelity are placed. These well types face higher friction and torque during drilling due to their complex wellbore trajectories and narrow annular spaces. High-deviated sections often suffer from significantly reduced core sliding due to gravity, while small-diameter wells experience strong pressure transmission lag due to limited annular volume, making it difficult to respond promptly to downhole anomalies. In high-pressure oil and gas reservoirs, the pressure difference between formation fluid pressure and drilling fluid column pressure can reach high levels, making core samples highly susceptible to erosion by high-speed drilling fluid during core extraction. This leads to damage to the original pore structure, loss of oil and gas components, and severely impacts the accuracy of subsequent reservoir evaluation parameters. To this end, the closed core sampling technology employs a process of pre-filling a high-viscosity sealing fluid in the inner cylinder. As the core enters the inner cylinder, the sealing fluid is squeezed by the piston and evenly coated onto the surface of the core, forming a continuous and dense protective film that physically isolates the core from the wellbore fluid. This effectively prevents the core from being washed away and contaminated, preserves its original composition and morphology to the maximum extent, and provides a true and reliable geological sample for rock mechanics analysis, geochemical testing, and hydrocarbon evaluation.

[0003] However, the technical challenges are particularly prominent when performing closed coring in soft and fractured formations. Due to weak diagenesis and poor cementation, these formations are highly susceptible to wellbore instability under the vibration and cutting action of mechanical drilling, resulting in poor core column formation. Cores produced are often fragmented, flaky, or even powdery. Irregular rock cuttings and fragments easily accumulate and clog the inner cylinder inlet, the narrowing section of the core claw, and the lower part of the suspension device during the process of entering the inner cylinder through the core claw – a phenomenon known as "core blockage." Once blockage occurs, the downward flow of the sealing fluid is blocked, the piston cannot move downwards normally, leading to a sharp increase in pressure within the inner cylinder cavity, creating a "liquid lock" effect. Subsequent cores will be completely unable to enter the inner cylinder, resulting in coring failure. Existing closed coring tools often use solid force-transmitting structures for their suspension devices, lacking internal fluid channels and pressure regulation mechanisms. Their function is limited to connecting the inner and outer cylinder joints and enabling single-action rotation; they cannot guide the reverse flow of the sealing fluid, nor do they possess adaptive pressure release capabilities. When the release of the sealing fluid is obstructed, the pressure buildup cannot be automatically relieved by the existing structure. Operators can only rely on changes in vertical pressure monitored on the surface to make a judgment, but the lag in pressure transmission makes it difficult to determine the timing of intervention. In addition, after core plugging, cuttings are more likely to accumulate at the bottom edge of the wellbore, further increasing the risk of core failure.

[0004] In view of the above, this application is hereby submitted. Utility Model Content

[0005] The purpose of this utility model is to provide a suspension device for a closed coring tool in complex well conditions. By setting a one-way valve that can automatically respond to pressure changes in the hollow cavity of the suspension device, reverse conduction and automatic pressure release are achieved when the release of the sealing fluid is blocked. This solves the technical problem in the prior art where the suspension device is a solid structure without fluid channels and pressure regulation functions, which leads to pressure accumulation in the inner cylinder cavity when the release of the sealing fluid is blocked, forming a liquid lock and causing low coring success rate in soft and broken formations.

[0006] The present invention is achieved through the following technical solution: a suspension device for a closed coring tool in complex well conditions is provided. The suspension device is used to connect with the upper connector of the outer cylinder and the inner cylinder. The suspension device is provided with a hollow cavity that connects the inner cylinder cavity with the ground atmosphere. A one-way valve is provided in the hollow cavity. The one-way valve is designed to automatically open when the pressure in the inner cylinder cavity increases due to obstruction of the sealing fluid release, allowing the sealing fluid to be released upwards, thereby reducing the pressure in the inner cylinder cavity and enabling the core to enter smoothly.

[0007] Optionally, the suspension device includes a balance shaft and a suspension water distribution shaft, the balance shaft and the suspension water distribution shaft are fixedly connected to form a rigid transmission unit; the bottom of the suspension water distribution shaft is fastened to the top of the inner cylinder by threads. The suspension water distribution shaft is connected to the upper connector on the outer cylinder by a thread and is locked by the first screw to prevent loosening, ensuring that the torque of the drill assembly can be transmitted to both the outer and inner cylinders simultaneously.

[0008] Optionally, the hollow cavity of the balance shaft is connected to the inner cylinder cavity, and the first pressure relief check valve is located at the top of the hollow cavity; The first pressure relief check valve is configured such that when the pressure in the inner cylinder cavity increases due to obstruction of the sealing fluid release, the sealing fluid enters the hollow cavity and flows upward to push the first pressure relief check valve open, thereby releasing the sealing fluid upward.

[0009] Optionally, the top of the hollow cavity is provided with a mounting groove, the inner diameter of which is larger than the diameter of the hollow cavity, and the first pressure relief check valve is disposed in the mounting groove.

[0010] Optionally, the first pressure relief check valve includes a positioning sleeve, a spring, a positioning bead, and a check valve core. The positioning sleeve has a slot for installing the spring, and the two ends of the positioning bead abut against the spring and the check valve core, respectively. The first pressure relief check valve is configured such that when the sealing fluid is released normally, the spring pushes the check valve core to seal the top of the hollow cavity; when the release of the sealing fluid is obstructed, causing the pressure in the inner cylinder cavity to rise, the sealing fluid pushes the check valve core to move upward to compress the spring, release the seal, and allow the sealing fluid to be released upward from the gap between the check valve core and the mounting groove.

[0011] Optionally, the size of the slot is adapted to the size of the positioning bead, and the positioning bead can move along the axial direction of the slot.

[0012] Optionally, the suspension device includes a suspension component and a water distribution component. The suspension component is rotatably connected to the upper connector of the outer cylinder via a bearing assembly, and the bottom of the water distribution component is threadedly fastened to the top of the inner cylinder. The hollow cavity of the water separator is equipped with a second pressure relief check valve. The second pressure relief check valve is configured to automatically open and guide the sealing fluid to the hollow cavity of the water separator to release upward when the pressure in the inner cylinder cavity rises due to obstruction of the release of sealing fluid.

[0013] Optionally, the bearing assembly includes a bearing housing, an angular contact bearing, and a half-ring. The angular contact bearing carries a combined axial and radial load, and the half-ring is disposed in the bearing housing to axially position the suspension component. It also includes a second screw, which is used to connect the bearing housing on the suspension to the upper connector of the outer cylinder.

[0014] Optionally, the second pressure relief check valve includes a steel ball and a steel ball seat, the steel ball seat being fixed to the bottom of the suspension component, and the steel ball being embedded in the annular groove in the steel ball seat to form a sealing fit.

[0015] Optionally, the annular groove is larger than the diameter of the steel ball, and the steel ball can seal the upper end of the inner cylinder cavity; When the pressure in the inner cylinder cavity increases due to obstruction of the release of the sealing fluid, it can push the steel ball component to move upward in the annular groove, thereby releasing the seal on the upper end of the inner cylinder cavity and allowing the sealing fluid to enter the hollow cavity from the gap between the steel ball component and the annular groove.

[0016] Compared with the prior art, the embodiments of this utility model have the following advantages and beneficial effects: 1. This utility model embodiment integrates a pressure self-response one-way valve into the hollow cavity of the suspension device, constructing a micro adaptive system that integrates support, fluid guidance, and pressure regulation. Essentially, it utilizes the sealed fluid itself as a pressure signal medium and guiding fluid to convert the abnormal high pressure in the inner cylinder cavity into the opening and closing action of the one-way valve in real time, realizing intelligent regulation of "releasing when blocked and closing when unobstructed". During normal drilling, the valve is sealed to ensure zero contamination of the core cavity. When a blockage occurs, it can automatically trigger bypass pressure relief, which not only eliminates the risk of drilling fluid intrusion into the inner cylinder from the source, but also completely eliminates the core blockage problem caused by the sealed fluid lock effect, improving the success rate and operational safety of sealed core sampling in soft and broken formations, while maintaining the advantages of the suspension device's compact structure and ease of disassembly and maintenance.

[0017] 2. This utility model embodiment establishes a direct, gapless, and anti-loosening torque transmission chain from the drill string assembly to the inner cylinder by fixing the balance shaft and the suspension water distribution shaft together as a rigid transmission unit and using a double-safety method of threaded and screw locking to connect with the upper connector. This enables the inner and outer cylinders to rotate synchronously during drilling, maintaining the advantages of simple structure and good tool stability of the double-cylinder double-action structure. The rigid integrated design avoids the micro-motion wear and torque transmission lag problems caused by connection gaps in traditional split suspension devices. Combined with the pressure self-regulation function of the auxiliary pressure relief mechanism, it significantly improves the working reliability and service life of the double-action mode under complex well conditions of high torque and strong vibration while ensuring the complete insertion of the core column into the cylinder. It realizes the versatility and strengthening of the force transmission structure when the sealed coring tool quickly switches between double-cylinder double-action and double-cylinder single-action modes.

[0018] 3. The suspension device of this utility model embodiment, through the separate arrangement of the suspension component and the water distribution component, longitudinally decouples and axially connects the rotation isolation function of the bearing assembly and the pressure regulation function of the pressure relief check valve. In single-action mode, it achieves the parallel operation of the mechanical state of "outer rotation and inner stillness" and the fluid state of "release when blocked, close when open": the bearing assembly ensures that the rotational power of the outer cylinder is not transmitted to the inner cylinder, eliminating the risk of core blockage from the root; the second pressure relief check valve monitors and releases abnormal pressure in real time at the water distribution component, which is located near the inner cylinder, to avoid the liquid lock effect; the pressure relief fluid passes through the series path of the hollow cavity of the water distribution component and the through hole of the suspension component in sequence, which not only bypasses the dynamic sealing problem of the bearing assembly, but also maintains the sensitivity of pressure response. Ultimately, the sealed coring tool can maintain the absolute stillness and zero contamination of the core cavity in single-action mode, and also has the self-protection ability to automatically adapt to the blockage of complex formations, improving the success rate of coring in soft and broken formations and the reliability of the tool.

[0019] In general, this utility model provides a suspension device for a sealed coring tool in complex well conditions. By setting a one-way valve that can automatically respond to pressure changes in the hollow cavity of the suspension device, reverse conduction and automatic pressure release are achieved when the release of the sealing fluid is blocked. This achieves the purpose of building a fluid channel and pressure regulation function in the suspension device, preventing the accumulation of pressure in the inner cylinder cavity to form a liquid lock when the sealing fluid is blocked, and improving the success rate of coring in soft and broken formations. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1This is a schematic diagram of the suspension device structure provided in Embodiment 1 of this utility model; Figure 2 for Figure 1 Enlarged view of the structure at point A in the middle; Figure 3 This is a schematic diagram of the suspension device structure provided in Embodiment 2 of this utility model; Figure 4 for Figure 1 Enlarged view of the structure at point B in the middle.

[0022] The attached diagram shows the markings and corresponding component names: Hollow cavity, 2-balance shaft, 3-suspended water distribution shaft, 4-first screw, 5-first pressure relief check valve, 6-mounting groove, 7-positioning sleeve, 8-spring, 9-positioning ball, 10-check valve core, 11-slot, 12-suspension component, 13-water distribution component, 14-second pressure relief check valve, 15-bearing assembly, 16-bearing box, 17-angular contact bearing, 18-half ring, 19-second screw, 20-steel ball component, 21-steel ball seat, 22-annular groove. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this utility model, it should be noted that the terms "first", "second", "third", etc. are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Example

[0027] This utility model provides a suspension device for a sealed coring tool in complex well conditions. The suspension device is used to connect to the upper connector of the outer cylinder and the inner cylinder. The suspension device is provided with a hollow cavity 1 that connects the inner cylinder cavity to the ground atmosphere. A one-way valve is provided in the hollow cavity 1. The one-way valve is configured to automatically open when the pressure in the inner cylinder cavity increases due to obstruction of the release of sealing fluid, so as to release the sealing fluid upward, thereby reducing the pressure in the inner cylinder cavity and allowing the core to enter smoothly.

[0028] Specifically, the suspension device body, as the core load-bearing component of the sealed coring tool, is connected to the upper connector of the outer cylinder by a thread or suspension method at its upper part and docked with the inner cylinder body at its lower part, forming an axial force transmission path for the drill assembly; the interior is machined with a longitudinally through hollow cavity 1, which provides structural space for pressure balance and fluid drainage.

[0029] The upper connector of the outer cylinder is part of the outer cylinder assembly. The upper part is connected to drilling tools such as drill collars, and the lower part is connected to the suspension device. Its main function is to transmit drilling torque and drilling pressure. Its inner hole is connected to the hollow cavity 1 of the suspension device to form a drilling fluid circulation channel.

[0030] The inner cylinder is the core sampling cavity located inside the outer cylinder. Its upper end is sealed to the suspension device. The inner cylinder contains the core and the sealed fluid. Its top is connected to the wellhead atmosphere through the hollow cavity 1, forming the final cavity for the release of the sealed fluid.

[0031] The through hole in the hollow cavity 1 along the axis of the suspension device has an upper opening that leads to the annulus or the ground atmosphere, and a lower opening that connects to the top cavity of the inner cylinder, forming the only channel for the reverse flow of the sealed liquid, and also serving as the sensing path for pressure transmission.

[0032] The one-way valve is embedded in the valve seat structure in the middle of the hollow cavity 1. It can be composed of a valve body, a valve ball (or valve disc) and a return spring 8. Its opening pressure threshold is slightly higher than the normal closed liquid pump injection pressure but lower than the safe pressure limit of the inner cylinder cavity, so as to realize automatic control of pressure response.

[0033] The sealing fluid is a high-viscosity protective fluid that is simultaneously coated on the surface of the core as it enters the inner cylinder via a dedicated pumping system. Under normal operating conditions, it flows downward along the inner wall of the inner cylinder, and becomes the source of pressure medium when it encounters a blockage.

[0034] In this embodiment of the invention, when the core enters the cylinder smoothly, the sealing fluid flows downward normally, the pressure in the inner cylinder cavity is stable, and the one-way valve remains sealed under the combined action of the spring force 8 and the static pressure of the drilling fluid, preventing backflow of drilling fluid into the annulus. When soft and broken core debris blocks the lower part of the inner cylinder or the core claw position, the continuously pumped sealing fluid cannot flow downward, accumulates in the top cavity of the inner cylinder, and the pressure rises sharply. This pressure acts on the lower end of the one-way valve through the hollow cavity 1. When the pressure exceeds the preset threshold, it pushes the valve ball to compress the spring 8 and open it upward, connecting the inner cylinder cavity with the upper annulus, allowing the sealing fluid to be released in reverse. The cavity pressure then decreases, relieving the reverse pushing resistance on the core, allowing it to continue entering the cylinder.

[0035] Example 1: Refer to Figure 1 As shown, the suspension device includes a balance shaft 2 and a suspension water distribution shaft 3. The balance shaft 2 and the suspension water distribution shaft 3 are fixedly connected to form a rigid transmission unit. The bottom of the suspension water distribution shaft 3 is fastened to the top of the inner cylinder by threads. The suspension water distribution shaft 3 is connected to the upper connector on the outer cylinder by threads and locked by the first screw 4 to prevent loosening, ensuring that the torque of the drill assembly can be transmitted to the outer cylinder and the inner cylinder at the same time.

[0036] Specifically, the balance shaft 2, as the upper component of the suspension device, has a pressure relief channel machined at its top, and its upper outer circle is precisely matched with the upper connector to achieve radial positioning; the interior has a through hollow cavity 1 for installing one-way valves, and it is connected to the upper end face of the suspension water distribution shaft 3, undertaking the functions of radial support, axial positioning and pressure balance, ensuring the overall alignment of the force transmission unit.

[0037] The suspended water distribution shaft 3 serves as the lower component of the suspension device. Its upper part is rigidly connected to the balance shaft 2, and its lower part is fastened to the top of the inner cylinder through threads. The outer circle has connecting threads that engage with the upper connector. It is a key carrier for realizing torque diversion and rigid force transmission. Its inner hole is connected to the hollow cavity 1 of the balance shaft 2 to form a closed fluid pressure relief channel. Water distribution holes are opened radially on the outer circle to guide drilling fluid into the annulus of the inner and outer cylinders.

[0038] The upper connector is threaded to connect with the outer diameter thread of the suspension water distribution shaft 3, and the lower part is screwed into the outer cylinder body; the radial hole on its side wall is used to install the first screw 4, which is the main path for the torque to be transmitted from the drill assembly to the outer cylinder, and at the same time provides external support and locking base for the suspension device.

[0039] The first screw 4 is a radial locking element. It passes through the threaded hole of the upper connector and presses against the anti-loosening groove or plane on the outer circle of the suspension water distribution shaft 3. It restricts the relative rotation of the threaded pair through mechanical interference, preventing the connection from loosening under impact, vibration and high torque. It is an anti-rotation insurance to ensure the reliability of the dual-action mode.

[0040] Because the balance shaft 2 and the suspension water distribution shaft 3 of this utility model are fixed together by end face teeth, high-strength bolts or interference fit, the relative displacement and gap between the components are eliminated, forming a rigid torque chain from the drill assembly → upper connector → suspension water distribution shaft 3 → inner cylinder, realizing the power transmission of synchronous rotation of the two cylinders.

[0041] In the dual-tube dual-action mode, the torque transmitted by the drill string assembly is output synchronously through two paths: the outer path drives the outer tube to rotate through the threaded pair between the upper joint and the outer tube, and the inner path transmits the torque directly to the inner tube through the threaded pair between the upper joint and the suspended water distribution shaft 3, and then through the overall structure of the rigid transmission unit, so that the inner and outer tubes obtain the same speed and direction of rotation. The first screw 4 continuously provides radial tightening force during dynamic drilling to counteract the loosening torque generated by the vibration of the threaded pair, ensuring that the connection between the suspended water distribution shaft 3 and the upper joint does not loosen under high-frequency alternating load, and maintaining the continuity and stability of torque transmission.

[0042] In a preferred embodiment of the present invention, the hollow cavity 1 of the balance shaft 2 is connected to the inner cylinder cavity, and the first pressure relief check valve 5 is disposed at the top of the hollow cavity 1. The first pressure relief check valve 5 is configured such that when the pressure in the inner cylinder cavity increases due to obstruction of the release of sealing fluid, the sealing fluid enters the hollow cavity 1 and flows upward to push the first pressure relief check valve 5 to open, thereby releasing the sealing fluid upward.

[0043] Specifically, the hollow cavity 1 of the balance shaft 2 serves as the main pressure relief channel. Its lower end connects to the top cavity of the inner cylinder via the hollow cavity 1 of the suspended water distribution shaft 3, and its upper end extends to the top of the balance shaft 2 to connect with the valve seat of the first pressure relief check valve 5. The cross-sectional area of ​​its internal through-hole matches the flow rate of the sealed liquid, ensuring both pressure transmission sensitivity and preventing excessive release that could lead to insufficient sealed liquid. The opening pressure threshold of the first pressure relief check valve 5 is set slightly higher than the normal sealed liquid pump pressure but lower than the safe pressure limit of the inner cylinder cavity, ensuring that it only opens under blockage conditions, thus achieving a one-way conduction function of "releasing upon overpressure and sealing under normal pressure".

[0044] For example, refer to Figure 2 As shown, the top of the hollow cavity 1 is provided with a mounting groove 6. The inner diameter of the mounting groove 6 is larger than the diameter of the hollow cavity 1. The first pressure relief check valve 5 is disposed in the mounting groove 6. The first pressure relief check valve 5 includes a positioning sleeve 7, a spring 8, a positioning bead 9, and a check valve core 10. The positioning sleeve 7 is provided with a slot 11 for mounting the spring 8. The two ends of the positioning bead 9 abut against the spring 8 and the check valve core 10, respectively. The first pressure relief check valve 5 is configured such that when the sealing fluid is released normally, the spring 8 pushes the check valve core 10 to seal the top of the hollow cavity 1; when the release of the sealing fluid is obstructed, causing the pressure in the inner cylinder cavity to rise, the sealing fluid pushes the check valve core 10 to move upward to compress the spring 8, releasing the seal and allowing the sealing fluid to be released upward from the gap between the check valve core 10 and the mounting groove 6.

[0045] In this embodiment of the invention, the spring 8 is pre-compressed in the mounting groove 6 by the positioning sleeve 7. The resulting downward thrust is transmitted to the one-way valve core 10 via the positioning bead 9, causing the lower end face of the one-way valve core 10 to fit tightly against the top orifice of the hollow cavity 1 to form an initial seal, blocking the communication between the sealing fluid and the annulus. When the inner cylinder is blocked, causing the sealing fluid pressure to rise, the hydraulic pressure acts upward on the lower end face of the one-way valve core 10. When the hydraulic thrust overcomes the force of the spring 8, the one-way valve core 10 moves upward in the mounting groove 6, the spring 8 is further compressed, and the lower end face of the one-way valve core 10 disengages from the orifice of the hollow cavity 1, releasing the seal. The sealing fluid flows into the mounting groove 6 from the opened orifice, and then flows upward into the annulus or wellhead through the annular gap between the outer circle of the valve core and the inner wall of the mounting groove 6, thus releasing the pressure. After the pressure drops, the spring 8 rebounds, and the valve core resets and re-seals.

[0046] Preferably, the size of the slot 11 is adapted to the size of the positioning bead 9, and the positioning bead 9 can move along the axial direction of the slot 11. The fitting gap between the slot 11 and the positioning bead 9 is controlled at 0.01-0.03 mm, which avoids jamming and prevents the bead from deflecting, so that the valve core can open smoothly without jamming and close and reset accurately.

[0047] Example 2: Refer to Figure 3 As shown, the suspension device includes a suspension component 12 and a water distribution component 13. The suspension component 12 is rotatably connected to the upper connector of the outer cylinder through a bearing assembly 15. The bottom of the water distribution component 13 is threadedly fastened to the top of the inner cylinder. A second pressure relief check valve 14 is provided in the hollow cavity 1 of the water distribution component 13. The second pressure relief check valve 14 is configured to automatically open and guide the sealing liquid to the hollow cavity 1 of the water distribution component 13 to release upward when the pressure in the inner cylinder cavity rises due to obstruction of the release of the sealing liquid.

[0048] Specifically, the suspension component 12 serves as a rotating isolation component in single-action mode. Its upper outer circle is embedded in the inner hole of the upper connector of the outer cylinder through the bearing assembly 15, forming a low-friction rotating pair. Its lower end face is rigidly connected to the water distribution component 13. An axial through hole is provided inside to connect the upper and lower end faces, forming an upward channel for the pressure-relieved fluid. It also has radial support and force transmission and steering functions to ensure that the inner cylinder remains relatively stationary during drilling.

[0049] The bearing assembly 15 is installed between the outer circle of the suspension member 12 and the inner hole of the upper connector of the outer cylinder. Its outer ring is interference-fitted with the upper connector, and its inner ring is interference-fitted with the suspension member 12. While bearing the drilling pressure and radial load, it realizes the relative rotation between the suspension member 12 and the outer cylinder. It is the core mechanical unit of the dual-cylinder single-action function. The upper connector of the outer cylinder is indirectly connected to the suspension member 12 through the bearing assembly 15. Its lower end is threaded to the outer cylinder body, which is the only path for the torque of the drill bit assembly to be transmitted to the outer cylinder. The inner hole provides rotational support and axial limit for the suspension member 12, forming the physical boundary of the outer cylinder rotating while the inner cylinder remains stationary.

[0050] The water distribution component 13 serves as an integrated carrier for pressure relief and diversion functions. Its lower outer circle is machined with connecting threads to engage with the top of the inner cylinder. Its upper end face is fixed to the lower end of the suspension component 12 by end face teeth or high-strength bolts to form a rigid whole. The upper end of the internal hollow cavity 1 is connected to the through hole of the suspension component 12, and the lower end is connected to the inner cylinder cavity. Water distribution holes are radially opened on the side wall to guide drilling fluid into the gap between the inner and outer cylinders.

[0051] The second pressure relief check valve 14 is embedded in the pressure control component in the middle of the hollow cavity 1 of the water distribution component 13. Its opening threshold is slightly higher than the normal pump pressure of the sealed liquid, and it directly senses the pressure change of the inner cylinder cavity and controls the opening and closing of the pressure relief channel.

[0052] In this embodiment of the invention, when the upper connector of the drill string assembly drives the outer cylinder to rotate, the torque is transmitted to the outer cylinder through the threaded pair of the upper connector. The inner hole of the upper connector is rotatedly isolated from the suspension component 12 through the bearing assembly 15, so that the suspension component 12, the water distribution component 13 and the inner cylinder as a whole remain relatively stationary, realizing single-action. After the sealing fluid is pumped in, it is coated downwards onto the core. When the core is blocked, the pressure in the inner cylinder cavity rises sharply. This pressure acts on the lower end of the valve core of the second pressure relief check valve 14 through the hollow cavity 1 of the water distribution component 13. When the hydraulic thrust overcomes the preload of the spring 8, the valve core moves upward and opens. The sealing fluid enters the upper part of the hollow cavity 1 through the valve port, and then flows upward through the internal through hole of the suspension component 12 to the annulus. After the pressure is released, the spring 8 drives the valve core to reset, resealing the inner cylinder cavity and preventing drilling fluid backflow.

[0053] For example, refer to Figure 4 As shown, the bearing assembly 15 includes a bearing housing 16, an angular contact bearing 17, and a semi-ring 18. The angular contact bearing 17 bears a combined axial and radial load, and the semi-ring 18 is disposed in the bearing housing to axially position the suspension member 12. The suspension also includes a second screw 19, which is used to connect the bearing housing 16 on the suspension member 12 to the upper joint of the outer cylinder.

[0054] Specifically, in single-action mode, the water distributor 13 rotates freely within the bearing housing 16 via the angular contact bearing 17. The semi-ring 18 engages with the annular groove of the water distributor 13 and presses against the upper end face of the inner ring of the bearing, rotating synchronously with the water distributor 13 while restricting its axial displacement. The drill string assembly drives the upper connector of the outer cylinder to rotate as a whole with the bearing housing 16, while the water distributor 13 and the inner cylinder remain relatively stationary due to bearing isolation. When switching to double-action mode, the double-action suspension assembly is replaced ( Figure 1 The water is directly transmitted to the inner cylinder through the suspended water distribution shaft 3, so as to achieve rigid synchronous rotation of the outer cylinder and the inner cylinder.

[0055] Therefore, Example 1 is a dual-action suspension device, and Example 2 is a single-action suspension device. In actual operation, the operator can replace the suspension device according to actual needs to achieve the purpose of dual-action or single-action. Because the dual-action suspension device in Example 1 adopts the same mechanical interface, flow channel layout and pressure relief logic as the single-action suspension device in Example 2, it forms a standardized replaceable module. The conversion between dual-tube dual-action and dual-tube single-action functions can be achieved simply by replacing the entire suspension device.

[0056] Based on formation predictions or real-time monitoring results, operators can switch the coring tool from the "inner cylinder static anti-clogging" mode to the "dual cylinder rotation for stability" mode simply by removing the single-action suspension device (including bearing assembly 15), replacing it with a rigid double-action suspension device, and tightening the upper and lower threads. The modular design retains the advantages of both working modes while eliminating the complexity of on-site adjustments and the risk of misoperation through standardized interfaces. This allows the tool to adapt to complex well conditions, ranging from soft and fractured formations to relatively intact formations, in a simple and reliable manner, improving the flexibility and economy of closed coring operations.

[0057] Returning to the embodiments of this utility model, as a preferred embodiment of this utility model, the second pressure relief check valve 14 includes a steel ball 20 and a steel ball seat 21. The steel ball seat 21 is fixed to the bottom of the suspension member 12, and the steel ball 20 is embedded in the annular groove 22 in the steel ball seat 21 to form a sealing fit.

[0058] Specifically, after the steel ball seat 21 is installed at the bottom of the suspension component 12, the annular groove 22 is directly opposite the lower end opening of the hollow cavity 1 of the suspension component 12. The steel ball component 20 is embedded in the groove under the action of gravity and the static pressure of the sealing liquid, forming an initial seal. When the inner cylinder is blocked, causing the sealing liquid pressure to rise, the hydraulic pressure acts on the lower hemisphere of the steel ball component 20, generating an upward axial thrust. When the thrust exceeds the sum of the weight of the steel ball component 20, the static pressure of the liquid column, and the elastic resistance of the groove contact, the steel ball component 20 is pushed away from the annular groove 22 and moves up a few millimeters along the hollow cavity 1. The sealing pair is instantly released, and the sealing liquid flows into the hollow cavity 1 from the annular gap between the steel ball component 20 and the groove, and is released upward into the annulus. After the pressure drops, the steel ball component 20 falls back into the groove under its own weight and the action of liquid backflow, and the line contact seal is restored.

[0059] More preferably, the diameter of the annular groove 22 is larger than that of the steel ball 20, and the steel ball 20 can seal the upper end of the inner cylinder cavity. When the pressure in the inner cylinder cavity increases due to obstruction of the release of the sealing liquid, the steel ball 20 can be pushed to move upward in the annular groove 22, releasing the seal on the upper end of the inner cylinder cavity, allowing the sealing liquid to enter the hollow cavity 1 from the gap between the steel ball 20 and the annular groove 22. Specifically, in this embodiment of the present invention, because the inner diameter of the groove is larger than the diameter of the steel ball 20, the liquid flows upward into the hollow cavity 1 of the suspension member 12 from the annular gap between the outer circle of the steel ball 20 and the inner wall of the groove, and then discharges into the annular space. After the pressure drops, the steel ball 20 falls back to the upper end orifice of the inner cylinder cavity under its own weight, and a new line contact seal is formed.

[0060] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model. It should be noted that the structures or components illustrated in the accompanying drawings are not necessarily drawn to scale, and descriptions of well-known components, processing techniques, and processes are omitted to avoid unnecessarily limiting the utility model.

Claims

1. A suspension device for a closed coring tool in complex well conditions, the suspension device being used to connect to the upper connector of the outer cylinder and the inner cylinder, characterized in that, The suspension device is provided with a hollow cavity (1) that connects the inner cylinder cavity with the ground atmosphere, and a one-way valve is provided in the hollow cavity (1). The one-way valve is designed to automatically open when the pressure in the inner cylinder cavity increases due to obstruction of the sealing fluid release, thereby allowing the sealing fluid to be released upwards, reducing the pressure in the inner cylinder cavity and enabling the core to enter smoothly.

2. The suspension device for a closed coring tool in complex well conditions according to claim 1, characterized in that, The suspension device includes a balance shaft (2) and a suspension water distribution shaft (3). The balance shaft (2) and the suspension water distribution shaft (3) are fixedly connected to form a rigid transmission unit. The bottom of the suspension water distribution shaft (3) is fastened to the top of the inner cylinder by threads. The suspended water distribution shaft (3) is connected to the upper connector on the outer cylinder by a thread, and is locked by a first screw (4) to prevent loosening, so that the torque of the drill assembly can be transmitted to the outer cylinder and the inner cylinder at the same time.

3. A suspension device for a closed coring tool in complex well conditions according to claim 2, characterized in that, The one-way valve includes a first pressure relief one-way valve (5), the hollow cavity (1) of the balance shaft (2) is connected to the inner cylinder cavity, and the first pressure relief one-way valve (5) is disposed at the top of the hollow cavity (1); The first pressure relief check valve (5) is configured such that when the pressure in the inner cylinder cavity increases due to obstruction of the release of the sealing fluid, the sealing fluid enters the hollow cavity (1) and flows upward to push the first pressure relief check valve (5) to open, thereby releasing the sealing fluid from the top.

4. A suspension device for a closed coring tool in complex well conditions according to claim 3, characterized in that, The top of the hollow cavity (1) is provided with an installation groove (6), the inner diameter of the installation groove (6) is larger than the diameter of the hollow cavity (1), and the first pressure relief check valve (5) is disposed in the installation groove (6).

5. A suspension device for a closed coring tool in complex well conditions according to claim 4, characterized in that, The first pressure relief check valve (5) includes a positioning sleeve (7), a spring (8), a positioning bead (9) and a check valve core (10). The positioning sleeve (7) has a slot (11) for installing the spring (8). The two ends of the positioning bead (9) abut against the spring (8) and the check valve core (10) respectively. The first pressure relief check valve (5) is configured such that when the sealing fluid is released normally, the spring (8) pushes the check valve core (10) to seal the top of the hollow cavity (1); when the release of the sealing fluid is blocked, causing the pressure in the inner cylinder cavity to rise, the sealing fluid pushes the check valve core (10) to move upward to compress the spring (8), release the seal and allow the sealing fluid to be released upward from the gap between the check valve core (10) and the mounting groove (6).

6. A suspension device for a closed coring tool in complex well conditions according to claim 5, characterized in that, The size of the slot (11) is adapted to the size of the positioning bead (9), and the positioning bead (9) can move along the axial direction of the slot (11).

7. A suspension device for a closed coring tool in complex well conditions according to claim 1, characterized in that, The suspension device includes a suspension component (12) and a water distribution component (13). The suspension component (12) is rotatably connected to the upper connector of the outer cylinder through a bearing assembly (15). The bottom of the water distribution component (13) is threadedly fastened to the top of the inner cylinder. The hollow cavity (1) of the water distribution component (13) is provided with a second pressure relief check valve (14). The second pressure relief check valve (14) is configured to automatically open and guide the sealing liquid to the hollow cavity (1) of the water distribution component (13) to release upward when the pressure in the inner cylinder cavity rises due to obstruction of the release of sealing liquid.

8. A suspension device for a closed coring tool in complex well conditions according to claim 7, characterized in that, The bearing assembly (15) includes a bearing housing (16), an angular contact bearing (17), and a half ring (18). The angular contact bearing (17) bears a combined axial and radial load, and the half ring (18) is disposed in the bearing housing to axially position the suspension component (12). It also includes a second screw (19) for connecting the bearing housing (16) on the suspension (12) to the upper connector of the outer cylinder.

9. A suspension device for a closed coring tool in complex well conditions according to claim 7, characterized in that, The second pressure relief check valve (14) includes a steel ball (20) and a steel ball seat (21). The steel ball seat (21) is fixed to the bottom of the suspension member (12). The steel ball (20) is embedded in the annular groove (22) in the steel ball seat (21) to form a sealing fit.

10. A suspension device for a closed coring tool in complex well conditions according to claim 9, characterized in that, The annular groove (22) is larger than the diameter of the steel ball (20), and the steel ball (20) can seal the upper end of the inner cylinder cavity; When the pressure in the inner cylinder cavity increases due to obstruction of the release of sealing fluid, the steel ball (20) can be pushed to move upward in the annular groove (22) to release the seal on the upper end of the inner cylinder cavity, so that the sealing fluid can enter the hollow cavity (1) from the gap between the steel ball (20) and the annular groove (22).

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