Coring device suitable for ultra-deep wells, device assembly method and method for drilling and coring

Abstract

This invention belongs to the field of oil and gas exploration and development technology, and particularly relates to a coring device, device assembly method, and drilling coring method suitable for ultra-deep wells. The coring device includes an upper connector, an inner cylinder assembly, an outer cylinder assembly, a core claw assembly, a coring drill bit, and a shock absorption assembly. The shock absorption assembly is located inside the upper connector near the bottom and has a first fluid channel. The inner cylinder assembly is placed inside the outer cylinder assembly, and the two are axially limited by an anti-detachment mechanism, with an annular structure between them. The inner cylinder assembly has a flow channel hole communicating with the annular structure. The top of the outer cylinder assembly is spirally fastened to the upper connector, and the bottom is connected to the coring drill bit. The top of the inner cylinder assembly and the shock absorption assembly are axially movable, and the core claw assembly is inside the coring drill bit and fixed to the bottom of the inner cylinder assembly. The components of this technical solution work together to cope with the complex and harsh environment of ultra-deep wells, ensuring smooth coring operations and improving the success rate and quality of coring.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas exploration and development technology, and particularly relates to a coring device, device assembly method and drilling coring method suitable for ultra-deep wells. Background Technology

[0002] Deep-earth oil and gas resources are abundant, representing a significant next-generation area for oil and gas exploration and development in China. In the process of oil and gas exploration, development, and reserve assessment, core drilling technology plays an indispensable role as a crucial means of obtaining the most direct geological core data. With increasing well depths, the bottom-hole environment becomes increasingly harsh, and drilling conditions become increasingly complex. The characteristics of ultra-deep wells, such as their depth and small borehole size, result in poor stability and low strength of core drilling tools. Under conditions of high temperature and high-volume drilling fluid circulation, critical components such as the mandrel and outer cylinder suffer severe erosion, which greatly affects the erosion resistance, temperature resistance, and mechanical strength of the core drilling tools, thus posing a serious threat to the quality of core samples.

[0003] Firstly, there is the issue of core damage and blockage caused by the vibration of the coring tool. In ultra-deep well drilling, due to the great depth, the length and flexibility of the drill string, and its poor stability, the coring tool will generate irregular vibrations. This vibration will damage the core, causing broken rock cuttings to accumulate in the inner barrel, leading to problems such as core blockage and core grinding, which seriously affects the core recovery rate and single-barrel footage.

[0004] Secondly, there is the impact of temperature on the mechanical properties of the tool and the required drilling fluid circulation rate. High temperatures at the bottom of the well not only negatively affect the mechanical properties of the coring tool, but also require a higher drilling fluid circulation rate to ensure effective cuttings removal. Currently, the flow channels drilled into the central shaft of the coring tool allow the high-temperature, high-speed drilling fluid to repeatedly erode the outer casing, exacerbating erosion and causing significant damage to its mechanical properties, posing a major downhole safety risk.

[0005] Thirdly, there are drawbacks to the conventional method of adjusting the assembly gap of coring tools. During the assembly process, conventional coring tools require adjusting the gap between the inner cylinder and the inner step of the drill bit to allow the core to enter the inner cylinder. Taking the "Sichuan-style" coring tool as an example, the adjustment nut, pressure cap, and brake ring are usually used to achieve the adjustment and locking functions. However, this method requires a straight groove to be cut on the mandrel. This straight groove cannot be sealed, forming a drilling fluid channel. As a result, when high-pressure, high-speed drilling fluid flows through, it causes severe erosion to the mandrel, pressure cap, brake ring, and adjustment nut.

[0006] Fourthly, there is the problem of inner cylinder swaying hindering core entry and causing core blockage. During ultra-deep well drilling, the drill string is highly flexible and has a large swing amplitude, which creates a certain gap between the inner and outer cylinders of the coring tool. This causes the inner cylinder to sway and deviate from the axis of the outer cylinder. When the core enters the inner cylinder, it forms a step, which hinders the entry of the core and leads to core blockage.

[0007] Fifth is the problem of core blockage caused by the conventional inner cylinder structure. Conventional coring tools use cylindrical steel pipes as the inner cylinder for core sampling. When the core enters the inner cylinder, due to factors such as the lithology of the strata, tool vibration, and the small gap between the core and the inner wall of the inner cylinder, broken rock fragments can easily accumulate in the inner cylinder, causing core blockage.

[0008] Finally, there are shortcomings in existing core claw structures. Ultra-deep wells have complex downhole conditions and long tripping times. Currently, the commonly used self-locking core claw structures have many problems, such as reduced friction due to core claw wear and ineffective shrinkage when the core claw adheres to the connecting sleeve. These problems frequently cause core extraction, which has a significant negative impact on core sampling in ultra-deep wells. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of the existing technology by proposing a coring device, device assembly method, and drilling coring method suitable for ultra-deep wells. Based on the characteristics of reasonable structure, convenient operation, and easy realization of functions of the coring device, it improves the safety, stability, and efficiency of ultra-deep well coring, which is of great significance for obtaining high-quality geological data and supporting the exploration and development of deep-earth oil and gas resources.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: A coring device suitable for ultra-deep wells includes an upper connector, an inner cylinder assembly, an outer cylinder assembly, a core claw assembly, a coring bit, and a shock absorption assembly. The shock absorption assembly is coaxially and movably embedded inside the upper connector, located near the bottom end of the upper connector, and has a first fluid channel axially penetrating its interior. The inner cylinder assembly is coaxially disposed inside the outer cylinder assembly and is axially limited to the outer cylinder assembly by an anti-detachment mechanism; an annular structure is pre-formed between the inner and outer cylinder assemblies, and several flow channels communicating with the annular structure are formed on the inner cylinder assembly. The top of the outer cylinder assembly is spirally fastened to the upper connector, and the coring bit is coaxially and fixedly connected to the bottom of the outer cylinder assembly. The top of the inner cylinder assembly is axially movably connected to the shock absorption assembly; the core claw assembly is coaxially disposed inside the coring bit and fixedly connected to the bottom of the inner cylinder assembly.

[0011] Preferably, the damping assembly includes a damping seat, a damping disc spring, and several positioning pins. The damping seat is clearance-fitted with the upper connector and includes an integrally formed base structure and a connecting cylinder structure. The connecting cylinder structure has several positioning holes spaced circumferentially. The top of the inner cylinder assembly is inserted into the connecting cylinder structure of the damping seat and is clearance-fitted with it. Near the top end of the inner cylinder assembly, several straight waist holes are spaced circumferentially, corresponding one-to-one with the positioning holes and extending axially. All positioning pins pass through the corresponding positioning holes and are inserted into the corresponding straight waist holes, allowing the inner cylinder assembly to be axially movablely connected to the damping seat. The damping disc spring is coaxially disposed in the connecting cylinder structure of the damping seat and, after being compressed, is engaged between the base structure and the inner cylinder assembly.

[0012] Preferably, the anti-detachment mechanism includes a bearing component; the bearing component is coaxially sleeved on the inner cylinder assembly, the outer wall of the inner cylinder assembly is provided with an upper limiting step, the inner wall of the outer cylinder assembly is provided with a lower limiting step, and the bearing component is located between the upper limiting step and the lower limiting step; the upper limiting step and the lower limiting step cooperate to restrict the axial movement of the bearing component.

[0013] Preferably, a protective collar is provided inside the outer cylinder assembly at the position corresponding to the flow channel hole; the protective collar is tightly fitted to the inner wall of the outer cylinder assembly, and the outer cylinder assembly is provided with a locking step to prevent the protective collar from moving axially.

[0014] Preferably, the inner cylinder assembly includes an upper spindle, a ball seat, a telescopic adjustment mechanism, and a lower inner cylinder. The ball seat is coaxially disposed inside the telescopic adjustment mechanism and is coaxially and sealed to the upper spindle; a second fluid channel is axially provided inside the ball seat. The lower inner cylinder is coaxially disposed with the upper spindle and is axially adjustable and fastened to the upper spindle through the telescopic adjustment mechanism.

[0015] Preferably, the telescopic adjustment mechanism includes an adjusting nut, a polygonal retaining ring, and a locking nut. The adjusting nut is hollow and includes an integrally formed upper internal thread portion and a lower external thread portion. The upper internal thread portion is threadedly connected to the upper spindle, and the lower external thread portion is threadedly fastened to the lower inner cylinder. A polygonal through hole is formed at the center of the lower external thread portion. The ball seat includes an integrally formed coaxial upper ball support portion, a middle retaining ring fitting portion, and a lower threaded portion. The upper ball support portion is fastened to the inner wall of the upper spindle. The polygonal retaining ring is embedded between the ball seat and the adjusting nut. Its inner wall is clearance-fitted with the middle retaining ring fitting portion of the ball seat, and its outer wall is clearance-fitted with the polygonal through hole of the adjusting nut. The locking nut engages with the lower threaded portion of the ball seat to axially fix the polygonal retaining ring.

[0016] Preferably, the inner wall of the lower inner cylinder is provided with a plurality of straight chip discharge grooves at intervals along the circumference, and the straight chip discharge grooves extend axially to penetrate the entire lower inner cylinder.

[0017] Preferably, the cross-section of the linear chip removal groove is trapezoidal.

[0018] Preferably, the lower inner cylinder includes an upper cylinder and a lower cylinder arranged coaxially, and an inner cylinder straightening mechanism is connected between the upper cylinder and the lower cylinder, with a third fluid channel axially penetrating the interior of the inner cylinder straightening mechanism.

[0019] Preferably, the inner cylinder straightening mechanism includes a straightening sleeve, an upper connector, and a lower connector. The upper connector includes an integrally formed locking connection part I and a casing part; the locking connection part I is threadedly fastened to the upper cylinder body. The straightening sleeve is coaxially sleeved on the outside of the casing part, with its inner annular surface having a clearance fit with the casing part and its outer annular surface having a clearance fit with the inner wall of the outer cylinder assembly; the straightening sleeve is provided with a channel structure for drilling fluid to pass through. The lower connector includes an integrally formed locking connection part II and a connector connection part; the locking connection part II is threadedly fastened to the casing part, and the lower cylinder body is threadedly fastened to the connector connection part.

[0020] Preferably, the channel structure includes a plurality of inner flow channels spaced circumferentially along the inner annular surface of the straightening sleeve and outer flow channels spaced circumferentially along the outer annular surface of the straightening sleeve.

[0021] Preferably, the core claw assembly includes an annular clamp seat and a core claw body. A clamping notch is axially extended through one side of the core claw body; at the bottom end of the core claw body, wedge-shaped locking protrusions are spaced circumferentially, with a drainage groove between adjacent wedge-shaped locking protrusions; the top end of the core claw body is clearance-fitted with the inner wall of the inner cylinder assembly, allowing the core claw body and the inner cylinder assembly to move circumferentially and axially. The annular clamp seat is threadedly fastened to the bottom of the inner cylinder assembly, and the interior of the annular clamp seat has a tapered surface that is wider at the top and narrower at the bottom, which wedges with the wedge-shaped locking protrusions of the core claw body.

[0022] Preferably, the top of the core claw body is provided with arc-shaped spring plates that bend toward the central axis at intervals along the circumferential edge.

[0023] Preferably, the outer cylinder assembly includes a differential short section and an outer cylinder body that are coaxially threaded and fastened together.

[0024] A method for assembling a core-collecting device includes the following steps: S11, Assemble the outer cylinder assembly at the coring site, hoist the outer cylinder assembly to the target wellhead, and then use slips to clamp the outer cylinder assembly; S12, perform the inner cylinder assembly assembly operation above the outer cylinder assembly, and axially connect the shock absorption assembly to the top of the inner cylinder assembly to place the assembled inner cylinder assembly into the outer cylinder assembly, and use the anti-detachment mechanism to axially limit and prevent the inner cylinder assembly from detaching from the outer cylinder assembly. S13, fasten the upper connector to the top of the outer cylinder assembly through threads. At this time, the upper connector covers the vibration damping assembly and is clearance-fitted with the vibration damping assembly. S14, using a lifting sub to extract the assembled coring device from the target well as a whole; S15, Install the core claw assembly at the bottom of the inner cylinder assembly; S16, Install the core drill bit at the bottom of the outer cylinder assembly.

[0025] Preferably, in step S11, assembling the outer cylinder assembly includes coaxially threading the differential short section to the outer cylinder body.

[0026] Preferably, in step S12, the inner cylinder assembly operation includes the following steps: S121, After assembling the lower inner cylinder, use the inner cylinder chuck to place the lower inner cylinder on the end face of the outer cylinder assembly; S122, to coaxially and securely connect the ball seat to the bottom of the upper spindle; S123, rotate the adjusting nut and the bottom of the upper spindle by threading them together, so that the adjusting nut is rotated to the preset position of the upper spindle; S124, Select a polygonal snap ring with a suitable thickness and fit the polygonal snap ring onto the middle snap ring mating part of the ball seat to ensure that the polygonal snap ring and the polygonal through hole of the adjusting nut can fit tightly. S125, the locking nut is threadedly fastened to the lower threaded part of the ball seat to axially fix the polygonal snap ring; S126, insert the protective collar into the differential short section, and then put the anti-detachment mechanism onto the upper spindle; S127 After installing the shock absorber assembly onto the upper spindle, tighten the top of the lower inner cylinder to the adjusting nut at the bottom of the upper spindle.

[0027] Preferably, in step S121, assembling the lower inner cylinder includes the following steps: assembling the inner cylinder straightening mechanism, that is, coaxially sleeve the straightening sleeve on the outside of the sleeve part of the upper connector, and then thread-tightly connecting the locking connection part II of the lower connector to the sleeve part; thread-tightly connecting the locking connection part I of the upper connector to the upper cylinder body; and thread-tightly connecting the lower cylinder body below the connector connection part of the lower connector to the lower cylinder body.

[0028] Preferably, in step S127, installing the shock absorber assembly onto the upper spindle includes the following steps: S1271, the damping disc spring is coaxially placed into the connecting cylinder structure of the damping seat; S1272, insert the top of the inner cylinder assembly into the connecting cylinder structure, and compress and pre-tighten the damping disc spring in conjunction with the base structure of the damping seat; S1273, screw in the corresponding positioning pins into all the positioning holes of the shock absorber seat. After the positioning pins pass through the positioning holes, they are inserted into the straight waist hole on the inner cylinder assembly, so that the inner cylinder assembly and the shock absorber seat are axially connected.

[0029] Preferably, it also includes step S17, namely: S171, check whether the gap between the inner step of the core drill bit and the core claw assembly is within the range of 5 mm to 15 mm; if not, proceed to step S172; if yes, proceed directly to step S176. S172, separate the differential short section from the outer cylinder body, and lift the differential short section and the inner cylinder assembly together to expose the telescopic adjustment mechanism; S173, after removing the lower inner cylinder from the adjusting nut of the telescopic adjustment mechanism, remove the locking nut and the polygonal snap ring from the ball seat in sequence; S174, after adjusting the position of the adjusting nut on the upper spindle by rotating, reinstall the polygonal snap ring and locking nut onto the ball seat in sequence; S175, after reconnecting the lower inner cylinder to the adjusting nut, lower the inner cylinder assembly and the differential short section together, and reconnect the differential short section to the outer cylinder body, then return to step S171. S176, no adjustment of the axial dimension of the inner cylinder assembly is required.

[0030] A drilling and coring method suitable for ultra-deep wells, employing a coring device suitable for ultra-deep wells according to this technical solution, includes the following steps: S21. After completing the assembly of the coring device, connect the coring device to the bottom of the drill string of the upper drill string and carry out the drilling operation in accordance with the drilling operation procedures. S22, perform cyclic removal of aftereffects; during this period, when the coring bit of the coring device is still 2 to 3 drill pipes away from the bottom of the well, connect the top drive drilling device to the upper drill string and perform cyclic lowering operation, using light pressure and slow rotation to ream the coring device to the bottom. S23, steel balls are inserted into the inner cylinder device to seal the inner cylinder assembly; S24, start the coring drilling operation. When the coring drilling reaches the predetermined coring length, the coring operation is completed.

[0031] Preferably, during the drilling operation in step S21, when the coring device enters the open hole section, a short trip tripping operation is performed, and drilling data including the suspended weight and drilling pressure during the lifting and lowering of the coring device are recorded.

[0032] Preferably, during the core cutting operation in step 24, when the lifting force exceeds 50kN, the core extractor is lowered to its original suspended weight; the top drive drilling device is started, and the rotation speed of the core extractor is set in the range of 20~50rpm; then the core extractor is raised using the reverse reaming method until the core is raised to the wellbore.

[0033] The beneficial effects of this invention are: I. A shock absorption assembly was installed. 1) Reducing vibration damage to cores: The damping disc springs in the damping assembly effectively absorb and buffer the energy transmitted to the inner cylinder assembly due to drill string vibration during core sampling. In ultra-deep well drilling, the drill string is long and highly flexible, resulting in severe vibration. The damping assembly, through its structural design, connects the inner cylinder assembly and the upper connector axially, working in conjunction with the buffering effect of the damping disc springs to stabilize the inner cylinder assembly. This reduces the possibility of core breakage due to vibration, thereby improving core integrity and facilitating the acquisition of high-quality core samples.

[0034] 2) Stabilizing the position of the inner cylinder assembly: The shock absorber and the inner cylinder assembly are axially connected via locating pins and other structures. This allows for a certain axial displacement of the inner cylinder assembly to accommodate vibrations, while ensuring its relative stability within a certain range. This helps prevent the inner cylinder assembly from colliding with the outer cylinder assembly or causing structural damage due to excessive shaking, further ensuring the smooth progress of the coring operation.

[0035] Second, an anti-detachment mechanism is incorporated to prevent the inner cylinder assembly from dislodging. The bearing components of the anti-detachment mechanism, in conjunction with the upper limiting step on the outer wall of the inner cylinder assembly and the lower limiting step on the inner wall of the outer cylinder assembly, precisely restrict the axial movement of the bearing components, thereby effectively preventing the inner cylinder assembly from detaching from the outer cylinder assembly. In the complex working conditions of ultra-deep wells, the twisting and swaying of the drill string may cause the inner cylinder assembly to tend to detach. This anti-detachment mechanism significantly improves the structural stability and safety of the coring device, avoiding coring failure or even downhole accidents due to inner cylinder detachment.

[0036] Third, a protective collar is installed to protect the outer cylinder assembly from erosion. The protective collar, positioned inside the outer cylinder assembly corresponding to the flow channel hole, fits tightly against the inner wall of the outer cylinder assembly and is fixed in axial position by a locking step. When drilling fluid flows out of the flow channel hole in the inner cylinder assembly, the protective collar can withstand the direct erosion of the drilling fluid, preventing high-speed, high-temperature drilling fluid from directly impacting the inner wall of the outer cylinder assembly. This effectively reduces erosion of the outer cylinder assembly, extends its service life, lowers the safety risks caused by outer cylinder erosion, and improves the reliability of the coring device under high-temperature, high-volume drilling fluid circulation conditions.

[0037] IV. The inner cylinder assembly structure has been optimized. 1) Adjustable Axial Dimension: The telescopic adjustment mechanism in the inner cylinder assembly achieves adjustable and secure connection of the inner cylinder assembly's axial dimension through the cooperation of the adjusting nut, multi-sided snap ring, and locking nut. This design overcomes the drawbacks of conventional coring tool assembly gap adjustment methods, such as the problem of drilling fluid erosion of components caused by the straight groove in the mandrel in the "Sichuan-style" coring tool adjustment method. This technical solution can precisely adjust the gap between the inner cylinder and the drill bit's inner step, etc., without compromising the structural integrity and sealing of the inner cylinder assembly, facilitating core entry into the inner cylinder and improving the assembly accuracy and adaptability of the coring device.

[0038] 2) Improved cuttings removal efficiency and reduced friction: The straight cuttings removal grooves on the inner wall of the lower inner cylinder have a trapezoidal cross-section and extend axially throughout the entire lower inner cylinder. On the one hand, the trapezoidal structure facilitates the flow and removal of cuttings within the grooves, improving the efficiency of removing crushed cuttings from the inner cylinder and preventing core blockage caused by cuttings accumulation. On the other hand, the number and size of the straight cuttings removal grooves are designed according to the inner cylinder dimensions, reducing the contact arc length between the core and the inner cylinder wall, decreasing friction between the core and the inner cylinder, reducing core grinding, and improving the core recovery rate and single-cylinder advance.

[0039] 3) Inner cylinder straightening reduces core blockage: The inner cylinder straightening mechanism in the lower inner cylinder, through the connection of the straightening sleeve with the upper and lower joints and the clearance fit between the sleeve and the inner wall of the casing and outer cylinder assembly, effectively reduces the swaying and shaking of the inner cylinder caused by the high flexibility and large torsional amplitude of the drill string during ultra-deep well drilling. The straightening sleeve keeps the inner cylinder as consistent with the axis of the outer cylinder as possible, avoiding the formation of steps that would obstruct core entry into the inner cylinder, thereby reducing the incidence of core blockage and improving the success rate of coring operations.

[0040] V. The core claw assembly structure has been optimized for reliable core gripping. The structural design of the core claw body, such as the clamping notch on one side, the wedge-shaped locking protrusion and drainage groove at the bottom, and the arc-shaped spring plate at the top, provides excellent core gripping performance during core extraction. When the core enters, the wedge-shaped locking protrusion engages with the conical surface of the annular clamp seat, narrowing the clamping notch and gripping the core as it moves relative to the clamp. The arc-shaped spring plate assists in pushing the core claw body to retract and grip the core during core cutting, effectively solving the core extraction problem caused by reduced friction due to wear or adhesion to the connecting sleeve in conventional core claws. This improves the reliability of the core gripping assembly and ensures that the core can be extracted intact.

[0041] VI. Regarding the core-taking device structure of this technical solution, an assembly method for the core-taking device is provided. This assembly method assembles the outer cylinder assembly and the inner cylinder assembly separately and then performs overall assembly. The steps are clear and orderly, and can be assembled accurately and efficiently.

[0042] VII. The coring device based on this technical solution provides a drilling coring method suitable for ultra-deep well conditions. In this method, short tripping operations during the drilling process and recording relevant drilling data help to understand the downhole conditions in advance, providing a basis for adjusting subsequent coring drilling parameters. Operations such as circulating to eliminate aftereffects, connecting the top drive drilling unit, and using light pressure and slow rotation to ream to the bottom effectively cope with the complex formation environment and high temperature and pressure conditions at the bottom of ultra-deep wells. During the core cutting operation, specific operating procedures are adopted according to factors such as the pulling force, such as lowering the core when it exceeds 50kN, starting the top drive, and reaming, which improves the success rate of core cutting and reduces problems such as core damage or failure caused by improper core cutting. This allows the entire drilling coring process to better adapt to the harsh conditions of ultra-deep wells, improving coring quality and operational safety. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the overall half-section structure of a coring device suitable for ultra-deep wells; Figure 2 for Figure 1 A partially enlarged structural diagram; Figure 3 for Figure 2 A partially enlarged structural diagram; Figure 4 This is a schematic diagram of the radial structure of a half-section of the ball seat; Figure 5 This is a schematic diagram of the axial structure of the ball joint; Figure 6 A schematic diagram of the radial structure of the adjusting nut; Figure 7 A schematic diagram of the axial structure of the adjusting nut; Figure 8 This is a schematic diagram of the axial structure of a polygonal snap ring; Figure 9 This is a schematic diagram of the axial structure of the lower inner cylinder; Figure 10 This is a schematic diagram of the axonal structure of the inner cylinder straightening mechanism; Figure 11 This is a cross-sectional radial structural diagram of the inner cylinder straightening mechanism; Figure 12 A schematic diagram of the axial structure for straightening the sleeve; Figure 13 This is a schematic diagram of the axial structure of the core claw body; Figure 14 This is a schematic diagram of coring without an inner cylinder straightening mechanism. Figure 15 This is a schematic diagram of the core taking process with the inner cylinder uprighting mechanism in place.

[0044] In the picture: 1. Upper connector; 2. Core drill bit; 2.1 Inner step; 3. Vibration damping assembly; 3.1 Vibration damping disc spring; 3.2 Locating pin; 3.3 Vibration damping seat; 3.31 Base structure; 3.32 Connecting sleeve structure; 3.4 Locating hole; 3.5 Straight waist hole; 3.6 First fluid channel; 4. Anti-detachment mechanism; 4.1 Bearing component; 4.2 Semi-ring; 4.3 Upper limiting step; 4.4 Lower... 5. Limiting step; 6. Annular structure; 7. Flow channel hole; 8. Protective collar; 9. Locking step; 10.1. Inclined surface; 11. Upper spindle; 12. Ball seat; 13.1. Connecting cylinder; 14.2. Transition cylinder; 15.3. Intermediate retaining ring mating part; 16.4. Lower screw connection part; 17. Second fluid channel; 18. Adjusting nut; 19.1. Upper internal thread part; 10.2. Lower external thread part; 11. 3. Polygonal through hole; 13. Polygonal snap-fit ​​ring; 14. Locking nut; 15. Lower inner cylinder; 15.1. Straight chip removal groove; 15.2. Contact surface; 16. Upper cylinder; 17. Lower cylinder; 18. Inner cylinder straightening mechanism; 18.1. Straightening sleeve; 18.11. Inner flow channel; 18.12. Outer flow channel; 18.2. Upper connector; 18.21. Locking connection part I; 18.22. Casing section; 18.3, Lower joint; 18.31, Locking connection II; 18.32, Joint connection; 19, Third fluid channel; 20, Annular clamp seat; 20.1, Conical surface; 21, Core claw body; 21.1, Clamping notch; 21.2, Wedge-shaped locking protrusion; 21.3, Drainage groove; 21.4, Arc-shaped spring plate; 22, Differential short section; 23, Outer cylinder body; 24, Core. Detailed Implementation

[0045] To make the purpose, technical solution and advantages of the invention clearer, the technical solution of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the invention, but not all embodiments.

[0046] Therefore, the following detailed description of the 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 invention without inventive effort are within the scope of protection of the invention.

[0047] Example 1 This embodiment discloses a coring device (hereinafter referred to as "coring device") and a drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, Figure 1 (AA in the figure is a cross-section) As shown, it includes an upper connector 1, an inner cylinder assembly, an outer cylinder assembly, a core claw assembly, a core drill bit 2, and a shock absorption assembly 3. Among them: The upper connector 1 is a key component connecting the entire coring device to the upper drill bit. It transmits the drilling pressure and torque of the drill bit to the coring device through a threaded fastening connection, providing power support for the coring operation.

[0048] The shock absorption assembly 3 is coaxially and movably embedded inside the upper connector 1, and is located at one end near the bottom of the upper connector 1. A first fluid channel 3.6 is axially provided inside the assembly, which allows drilling fluid and other fluids to pass through during the drilling process.

[0049] The inner cylinder assembly is coaxially mounted inside the outer cylinder assembly and is axially limited by the anti-detachment mechanism 4. This structure ensures the stability of the inner cylinder assembly while allowing it to move axially relative to the outer cylinder assembly to a certain extent. Furthermore, the top of the outer cylinder assembly is screw-fastened to the upper connector 1, and the top of the inner cylinder assembly is axially movable to the shock-absorbing assembly 3 to achieve shock absorption.

[0050] An annular structure 5 is provided between the inner and outer cylinder assemblies, and several flow channel holes 6 communicating with the annular structure 5 are opened on the inner cylinder assembly. The annular structure 5 and the flow channel holes 6 on the inner cylinder assembly together form a circulation channel for drilling fluid, which helps to carry cuttings, cool the drill bit, and balance pressure. The core drill bit 2 is coaxially fixed to the bottom of the outer cylinder assembly. It is the component that directly contacts the formation rock and drills the core. Its structure and performance directly affect the efficiency and quality of core drilling. Therefore, the structure, type and material of the core drill bit 2 can be adapted to the formation characteristics.

[0051] The core claw assembly is coaxially mounted inside the core drill bit 2 and is fixedly connected to the bottom of the inner cylinder assembly. Its main function is to grab and fix the core during the core-taking process, prevent the core from falling off during the lifting process, and ensure that the core can smoothly enter the inner cylinder assembly and be completely removed.

[0052] Based on the aforementioned coring device suitable for ultra-deep wells, this technical solution possesses the following vibration reduction principles and advantages: Vibration damping principle: Based on the anti-detachment mechanism 4, the inner cylinder assembly moves axially within the outer cylinder assembly within a limited range, thus providing vibration damping space for the inner cylinder assembly. Furthermore, when the coring device experiences axial vibration during drilling, the inner cylinder assembly will undergo relative displacement with the outer cylinder assembly under the action of the damping assembly 3. The damping mechanism absorbs and offsets the vibration energy through its own axial elastic deformation or other buffering methods, thereby minimizing the vibration amplitude of the inner cylinder assembly and keeping it essentially stationary.

[0053] Advantages: The relative stability of the inner cylinder assembly is crucial for core preservation. Since the core at the lower inlet of the inner cylinder assembly is relatively fragile, excessive vibration can easily cause core breakage, affecting the integrity and quality of the core sample. This technical solution, through the action of a vibration damping mechanism, ensures that the core can enter the inner cylinder assembly smoothly, improving the success rate of core sampling and the quality of the core, providing reliable samples for subsequent geological analysis and research.

[0054] Based on the aforementioned coring device suitable for ultra-deep wells, the following drilling and coring method can be implemented using this technical solution: Preparation stage: Connect the upper connector 1 of the coring device to the upper drill string with threads to ensure a firm and reliable connection. At the same time, check whether all components of the coring device are installed in place and tightly connected to ensure the integrity and sealing of the device.

[0055] Drilling Stage: The drilling equipment is started, and the drilling pressure and torque are transmitted to the coring device through the upper drill string, driving the coring bit 2 to rotate and drill into the formation. During drilling, the drilling fluid is introduced into the coring device through the upper drill string, and then flows sequentially through the upper connector 1, the shock absorption assembly 3, the inner cylinder assembly, and the core claw assembly, finally reaching the coring bit 2 to cool, clean, and lubricate it, while carrying rock cuttings back to the surface through the wellbore annulus.

[0056] Core sampling stage: When the core drill bit 2 has drilled to a certain depth and reached the predetermined core sampling length, drilling is stopped and the drill string is slowly lifted. At this time, the core gripper assembly will firmly grasp the core to prevent it from falling off. As the drill string is lifted, the core gradually enters the inner cylinder assembly. The inner cylinder assembly remains relatively stable under the action of the shock absorption assembly 3, ensuring that the core can smoothly and completely enter the inner cylinder assembly.

[0057] Extraction stage: The coring device is pulled out of the well to the surface, and then the coring drill bit 2, core claw assembly and other components are disassembled. The core is taken out from the inner cylinder assembly and marked, sealed and preserved accordingly for subsequent geological analysis and research.

[0058] Example 2 This embodiment discloses a coring device (hereinafter referred to as "coring device") and a drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, based on Embodiment 1, as follows... Figure 2 As shown, its damping assembly 3 includes a damping seat 3.3, a damping disc spring 3.1, and several positioning pins 3.2.

[0059] The shock absorber seat 3.3 is clearance-fitted with the upper connector 1 and includes an integrally formed base structure 3.31 and a connecting cylinder structure 3.32. The connecting cylinder structure 3.32 is provided with a number of positioning holes 3.4 at circumferential intervals. The positioning holes 3.4 are threaded holes.

[0060] The top of the inner cylinder assembly is inserted into the connecting sleeve structure 3.32 of the shock absorber 3.3, and is clearance-fitted with the connecting sleeve structure 3.32. Near the top end of the inner cylinder assembly, several straight waist holes 3.5 are circumferentially spaced, corresponding one-to-one with the positioning holes 3.4 and extending axially. All positioning pins 3.2 pass through the corresponding positioning holes 3.4 and are inserted into the corresponding straight waist holes 3.5, allowing the inner cylinder assembly to be axially movable to the shock absorber 3.3. This fit allows the inner cylinder assembly to move slightly up and down within a certain range to cooperate with the shock absorption mechanism, while the connection of the positioning pins 3.2 ensures the relative positional relationship between the inner cylinder assembly and the shock absorber 3.3, keeping it radially stable. Furthermore, the positioning pins 3.2 and the positioning holes 3.4 are threaded.

[0061] The damping disc spring 3.1 is coaxially mounted in the connecting sleeve structure 3.32 of the damping seat 3.3. After being compressed and stored, it is engaged between the base structure 3.31 and the inner cylinder assembly, with its two ends contacting the base structure 3.31 and the inner cylinder assembly of the damping seat 3.3, respectively. When the drill bit is not vibrating, the damping disc spring 3.1 is in a compressed and stored state. The preload generated maintains a certain pressure between the inner cylinder assembly and the damping seat 3.3, thereby effectively suppressing the vibration amplitude of the inner cylinder assembly when the drill bit vibrates.

[0062] In summary, during actual core drilling, when the drill string vibrates axially, the outer cylinder assembly will experience vertical vibration. Since the inner cylinder assembly is axially connected to the damping seat 3.3 via the locating pin 3.2, and a pre-tensioned damping disc spring 3.1 is installed between the inner cylinder assembly and the damping seat 3.3, the vibration amplitude of the inner cylinder assembly is effectively suppressed under the action of the damping disc spring 3.1 when the outer cylinder assembly vibrates, thus maintaining a relatively stable state. Based on this, the retrieved core is stored in the inner cylinder assembly, and the stability of the inner cylinder assembly is crucial for protecting the core. Through the action of the damping assembly 3, the damage to the core caused by drill string vibration is reduced, the probability of core blockage is decreased, and the core drilling footage is increased. This provides a strong guarantee for obtaining high-quality core samples in geological exploration, helps to more accurately understand the geological conditions of the formation, and improves the efficiency and quality of drilling work.

[0063] Example 3 This embodiment discloses a coring device (hereinafter referred to as "coring device") and a drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, based on Embodiment 1 or 2, the anti-detachment mechanism 4 plays a crucial role in ensuring a proper connection between the inner cylinder assembly and the outer cylinder assembly throughout the coring device. Its key function is to effectively prevent the inner cylinder assembly from detaching from the outer cylinder assembly while meeting the vibration damping requirements of the inner cylinder assembly, thus ensuring the smooth progress of the coring operation. Therefore, the key component of the anti-detachment mechanism 4 is the bearing 4.1, which is coaxially sleeved on the inner cylinder assembly, providing support between the inner and outer cylinder assemblies. This sleeved arrangement ensures a close connection between the bearing 4.1 and the inner cylinder assembly, enabling corresponding linkage effects with the axial movement of the inner cylinder assembly and the rotation of the outer cylinder assembly.

[0064] Specifically: an upper limiting step 4.3 is provided on the outer wall of the inner cylinder assembly, and a lower limiting step 4.4 is provided on the inner wall of the outer cylinder assembly. The bearing component 4.1 is located between the upper limiting step 4.3 and the lower limiting step 4.4. More specifically, the anti-detachment mechanism 4 also includes a semi-ring 4.2, which is located between the bearing component 4.1 and the upper limiting step 4.3.

[0065] The upper limiting step 4.3, as an important component restricting the axial movement of bearing component 4.1, works in conjunction with the lower limiting step 4.4 to constrain bearing component 4.1. When bearing component 4.1 is subjected to various external forces (such as forces generated by vibration or drill bit movement during the operation of the coring device) and may tend to move axially, the upper limiting step 4.3 can block bearing component 4.1 from above, preventing it from moving excessively upwards, thereby ensuring that bearing component 4.1 remains within a relatively reasonable axial position range.

[0066] The lower limiting step 4.4 is also a key structure used to restrict the axial movement of the bearing component 4.1. Working in conjunction with the upper limiting step 4.3, when the bearing component 4.1 tends to move downwards, the lower limiting step 4.4 can block it from below, preventing the bearing component 4.1 from moving excessively downwards and deviating from its normal working position. Through the cooperation of the upper limiting step 4.3 and the lower limiting step 4.4, the bearing component 4.1 is stably restricted between the two, so that the bearing component 4.1 can only move within a specific axial range. This effectively prevents the connection relationship between the inner cylinder assembly and the outer cylinder assembly from becoming disordered due to uncontrolled axial movement of the bearing component 4.1, thereby ensuring the stability and reliability of the entire core-taking device structure.

[0067] In summary, by coaxially mounting the bearing component 4.1 onto the inner cylinder assembly and using upper and lower limiting steps 4.3 and 4.4 to restrict the axial movement of the bearing component 4.1, the anti-detachment mechanism 4 effectively stabilizes the connection between the inner and outer cylinder assemblies. In the actual operation of the coring device, especially in complex environments with many uncertainties (such as strong vibrations and complex formation forces) like ultra-deep wells, this stable connection is crucial. It ensures that the inner cylinder assembly will not easily detach from the outer cylinder assembly, guaranteeing the integrity of the coring device and playing an indispensable role in ensuring smooth coring operations, obtaining high-quality core samples, and safeguarding downhole operations.

[0068] Example 4 In conventional coring tools, the flow channel hole 6, opened at a 45° angle on the inner cylinder assembly, serves as the main flow channel for drilling fluid. The high-temperature, high-speed drilling fluid ejected from the inner cylinder repeatedly scours the outer cylinder. Due to this prolonged scouring, the mechanical properties of the outer cylinder are significantly affected, leading to substantial downhole safety risks. This poses a serious threat to the smooth operation of coring and downhole safety. This embodiment discloses a coring device (hereinafter referred to as "coring device") and a coring method suitable for ultra-deep wells. Based on embodiments 1, 2, or 3, the flow channel hole 6 is opened at a 45° angle on the inner cylinder assembly. As a preferred embodiment of the present invention, targeted improvements have been implemented.

[0069] Inside the outer cylinder assembly, a protective collar 7 is installed at the location corresponding to the flow channel hole 6. This protective collar 7 fits tightly against the inner wall of the outer cylinder assembly, forming an effective protective barrier to prevent drilling fluid from directly eroding the outer cylinder assembly, thereby reducing the impact of erosion. To ensure the stability of the protective collar 7 during operation, a retaining step 8 is also provided inside the outer cylinder assembly to prevent axial movement of the protective collar 7. Notably, the angle between the retaining step 8 and the inner wall of the outer cylinder assembly is less than 90°. This inclined surface 8.1 fit effectively prevents the protective collar 7 from shrinking and deforming under pressure. This not only ensures the continuity of the protective effect of the protective collar 7, but also makes replacement relatively simple, thus saving maintenance costs.

[0070] Based on the above structure, for ease of installation, the top of the protective collar 7 can be used as a limiting step to restrict the axial movement of the anti-detachment mechanism 4.

[0071] In summary, the coring device disclosed in this embodiment effectively solves the problems of the outer cylinder assembly being easily eroded by drilling fluid, the existence of downhole safety risks, and the high cost in the prior art by setting up a protective collar 7 and a corresponding locking step 8, which is of great significance for improving the safety and economy of coring operations.

[0072] Example 5 Considering the drawbacks of conventional coring tool assembly gap adjustment methods, this embodiment discloses a coring device (hereinafter referred to as "coring device") and drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, based on embodiments 1, 2, 3 or 4, its inner cylinder assembly includes an upper mandrel 9, a ball seat 10, a telescopic adjustment mechanism and a lower inner cylinder 15.

[0073] The upper spindle 9, as an important component of the inner cylinder assembly, plays a supporting and connecting role in the upper part. It is one of the key connection hubs in the overall structure of the inner cylinder assembly and has a close connection with other components. For example, its top is connected to the vibration damping assembly, and the straight waist hole 3.5 and the flow channel hole 6 are opened on the upper spindle 9.

[0074] The ball seat 10 is coaxially mounted inside the telescopic adjustment mechanism and is coaxially and sealed to the upper mandrel 9. This sealed connection ensures that the fluid flowing through the ball seat 10 will not leak during core sampling, guaranteeing the stability and reliability of fluid transmission. To allow fluid to pass through the ball seat 10, a second fluid channel 11 is axially provided inside the ball seat 10. During core sampling, the ball seat 10 and the steel ball are mainly used to seal the circulation channel. That is, after core sampling, the steel ball is inserted and falls onto the ball seat 10, forming a sealed structure. This changes the circulation path of the drilling fluid, causing the drilling fluid to be pressurized.

[0075] The lower inner cylinder 15 is coaxially arranged with the upper mandrel 9 and is axially adjustable and securely connected to the upper mandrel 9 via a telescopic adjustment mechanism. The lower inner cylinder 15 is the part that directly contacts and stores the core. Its adjustable connection with the upper mandrel 9 ensures better adaptability to various situations during coring. For example, by adjusting the gap between the lower inner cylinder 15 (specifically, the core grab assembly connected to the bottom of the lower inner cylinder 15) and the drill bit inner step 2.1, the telescopic adjustment mechanism is a key component for achieving an axially adjustable and secure connection between the lower inner cylinder 15 and the upper mandrel 9. It can flexibly adjust the position of the lower inner cylinder 15 according to different formation conditions and coring requirements, thereby adjusting the overall axial dimension of the inner cylinder assembly and adjusting the corresponding gap to reduce the resistance of the core entering the lower inner cylinder 15. This ensures that the core can smoothly enter and be completely stored in the lower inner cylinder 15, achieving the best coring effect.

[0076] Example 6 This embodiment discloses a coring device (hereinafter referred to as "coring device") and a drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, based on embodiment 5, its telescopic adjustment mechanism includes an adjustment nut 12, a multi-sided snap ring 13 and a locking nut 14.

[0077] The adjusting nut 12 is hollow and includes an integrally formed upper internal threaded portion 12.1 and a lower external threaded portion 12.2. The upper internal threaded portion 12.1 can be adjusted to connect with the upper spindle 9, allowing the adjusting nut 12 to move flexibly relative to the upper spindle 9, thereby adjusting its axial position. The lower external threaded portion 12.2 is used to securely connect with the lower inner cylinder 15, ensuring a tight connection between the lower inner cylinder 15 and the adjusting nut 12. A polygonal through hole 12.3 (such as a quadrilateral through hole) is provided at the center of the lower external threaded portion 12.2. This through hole plays a crucial role in preventing the adjusting nut 12 from rotating and in the overall coordination of the telescopic adjustment mechanism.

[0078] The ball seat 10 includes an upper ball support part, a middle retaining ring fitting part 10.3, and a lower screw connection part 10.4, all integrally formed on the same axis. The upper ball support part includes a connecting cylinder 10.1 and a transition cylinder 10.2. The connecting cylinder 10.1 in the upper ball support part is tightly connected to the inner wall of the upper spindle 9. This connection method ensures the relatively fixed position of the ball seat 10 in the entire inner cylinder assembly, providing a stable foundation for subsequent adjustment and fitting operations.

[0079] A polygonal retaining ring 13 (such as a four-sided retaining ring) is embedded between the ball seat 10 and the adjusting nut 12. Its inner wall is in clearance fit with the middle retaining ring mating part 10.3 of the ball seat 10, and its outer wall is in clearance fit with the polygonal through hole 12.3 of the adjusting nut 12. Through this clearance fit, the relative movement of the components is supported, while the rotation of the adjusting nut 12 is restricted.

[0080] The locking nut 14 engages with the lower threaded portion 10.4 of the ball seat 10, and its axis passes through it. The main function of the locking nut 14 is to axially fix the polygonal retaining ring 13, ensuring the stability of the polygonal retaining ring 13 in the entire telescopic adjustment mechanism and preventing axial displacement during operation.

[0081] Based on the above structure, the axial dimension adjustment operation process of the inner cylinder assembly in this technical solution is as follows: Initial positioning with adjusting nut 12: When adjusting the overall axial dimension of the inner cylinder assembly, first rotate adjusting nut 12 and adjust it to a suitable position on the mandrel according to actual needs. This step is mainly achieved through the adjustable threaded connection between adjusting nut 12 and the upper mandrel 9. By rotating adjusting nut 12, it can be moved flexibly in the axial direction to find a preliminary suitable position.

[0082] Fine-tuning the adjusting nut 12: Next, fine-tune the adjusting nut 12 so that the edge of its polygonal through hole 12.3 is parallel to the middle retaining ring mating part 10.3 of the ball seat 10. The accuracy of this step is crucial for the correct insertion of the polygonal retaining ring 13 and the effective cooperation of the entire telescopic adjustment mechanism. Only by ensuring that the two are parallel can the polygonal retaining ring 13 be smoothly inserted and play its role in preventing the adjusting nut 12 from rotating.

[0083] Embedding the polygonal retaining ring 13: After completing the above fine-tuning, accurately embed the polygonal retaining ring 13 between the ball seat 10 and the adjusting nut 12, so that its inner wall is in clearance fit with the middle retaining ring mating part 10.3 of the ball seat 10, and its outer wall is in clearance fit with the polygonal through hole 12.3 of the adjusting nut 12. Through this embedding method, the polygonal retaining ring 13 can effectively restrict the rotation of the adjusting nut 12, thereby ensuring that the position of the adjusting nut 12 is relatively fixed in subsequent operations.

[0084] Locking nut 14 secures the polygonal snap-fit ​​ring 13: Subsequently, the locking nut 14 is tightened to the lower threaded portion 10.4 of the ball seat 10 to axially fix the polygonal snap-fit ​​ring 13. In this way, the position of the polygonal snap-fit ​​ring 13 in the entire telescopic adjustment mechanism is stabilized, further ensuring that the adjusting nut 12 will not rotate due to external forces or other factors, thus maintaining the stability of the entire mechanism.

[0085] Connecting the lower inner cylinder 15: Finally, fasten the lower inner cylinder 15 to the lower external thread 12.2 of the adjusting nut 12 to complete the axial dimension adjustment process of the entire inner cylinder assembly. Through this series of steps, the overall axial dimension of the inner cylinder assembly is precisely adjusted, enabling it to adapt to different coring operation requirements.

[0086] The telescopic adjustment mechanism in this technical solution, through its unique structural composition and standardized axial dimension adjustment operation procedure for the inner cylinder assembly, achieves effective adjustment of the overall axial dimension of the inner cylinder assembly. It also has advantages such as reliable locking and prevention of drilling fluid erosion, providing strong support for coring devices suitable for ultra-deep wells during coring operations, and helping to improve the efficiency and quality of coring operations.

[0087] Example 7 This embodiment discloses a coring device (hereinafter referred to as "coring device") and a drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, based on embodiment 5 or 6, a plurality of straight cuttings removal grooves 15.1 are arranged on the inner wall of the lower inner cylinder 15 in a circumferentially spaced manner. These straight cuttings removal grooves 15.1 exhibit axial extension and penetrate the entire lower inner cylinder 15, forming a complete cuttings removal channel, which provides convenient conditions for cuttings removal from a structural perspective.

[0088] Furthermore, the cross-section of the straight chip removal trough 15.1 is trapezoidal. This trapezoidal design has certain rationale: the shape of the trapezoid is relatively stable, which can ensure the structural strength of the chip removal trough itself, while also facilitating the flow of rock cuttings within the trough. Compared to some other shapes, the inclined side of the trapezoid can, to a certain extent, guide the rock cuttings smoothly through the chip removal trough, reducing the possibility of rock cuttings getting stuck within the trough.

[0089] Therefore, the linear chip conveying groove 15.1 provided in this technical solution has the following functions and advantages: Providing a chip removal channel: The presence of the straight chip removal channel 15.1 significantly improves the efficiency of removing rock cuttings from the inner cylinder. During core drilling, the drill bit generates a large amount of rock cuttings from breaking the rock. If these cuttings cannot be removed from the inner cylinder in time, they can easily accumulate inside. The straight chip removal channel 15.1, as a dedicated chip removal channel, allows the rock cuttings to be quickly discharged along the channel, effectively preventing rock cuttings from accumulating and causing core blockage, thus ensuring the smooth progress of the core drilling operation.

[0090] Controlling the contact arc length: The number and size of the straight chip removal grooves 15.1 are rationally designed according to the inner cylinder dimensions, so that the arc length of the contact surface 15.2 between the core and the inner cylinder wall on the same cross section can be controlled within 10mm, that is, the circumferential interval between adjacent straight chip removal grooves 15.1 is within 10mm. This design makes the contact surface area 15.2 between the core and the inner cylinder wall relatively small, thereby reducing the friction between the core and the inner cylinder.

[0091] Reduced core entry resistance: Lower friction means less resistance encountered when the core enters the inner cylinder. Reduced entry resistance allows the core to enter the inner cylinder more smoothly, further preventing core blockage caused by excessive entry resistance and improving the success rate and quality of core extraction.

[0092] In summary, the straight chip removal groove 15.1 set on the inner wall of the lower inner cylinder 15 plays an important role in ensuring the normal operation of the coring device and the efficient completion of coring operations, whether in terms of its setting method, cross-sectional shape, or its function of avoiding rock chip accumulation and reducing friction. It effectively improves the effect and reliability of coring operations.

[0093] Example 8 Considering the numerous challenges that arise in ultra-deep well drilling scenarios, coring operations face. The drill string is highly flexible and exhibits significant torsional amplitude, while a certain gap exists between the inner and outer cylinder components of the coring tool. These factors combined make the inner cylinder component prone to swaying and shaking. This swaying and shaking causes a certain deviation between the axes of the inner and outer cylinder components (which coincide with the drill bit's central axis), creating a step when the core enters the inner cylinder, obstructing its entry and ultimately leading to core blockage. This severely impacts the smooth progress and quality of coring operations. Therefore, this embodiment discloses a coring device (hereinafter referred to as "coring device") and a coring method suitable for ultra-deep wells. The lower inner cylinder 15 features a targeted improvement design. As a preferred embodiment of this invention, based on embodiments 5, 6, or 7, the lower inner cylinder 15 includes an upper cylinder 16 and a lower cylinder 17 coaxially arranged. This two-section structure facilitates the subsequent connection of the inner cylinder straightening mechanism 18 and lays the foundation for solving the swaying and shaking problem of the inner cylinder component.

[0094] Furthermore, an inner cylinder straightening mechanism 18 is connected between the upper cylinder 16 and the lower cylinder 17. The inner cylinder straightening mechanism 18 plays a key straightening role in the lower inner cylinder 15. Through a reasonable connection method, it is made to work closely with the upper cylinder 16 and the lower cylinder 17 to ensure the structural continuity and stability of the entire lower inner cylinder 15.

[0095] A third fluid channel 19 is axially integrated within the inner cylinder centering mechanism 18. This third fluid channel 19 is also of great importance in the fluid circulation system of the entire coring device, enabling the smooth flow of fluids such as drilling fluid within the device. For example, during coring operations, the drilling fluid can provide cooling and lubrication to the drill bit through this channel, while also helping to carry away impurities such as rock cuttings, maintaining the normal progress of coring operations. It works in conjunction with other fluid channels (such as the second fluid channel 11 in the ball seat 10 of the inner cylinder assembly) to improve the fluid circulation system of the coring device.

[0096] This technical solution has the following advantages: Centering Function: The core function of the inner cylinder centering mechanism 18 is to center the lower inner cylinder 15. When the drill bit twists or the inner cylinder assembly wobbles, the inner cylinder centering mechanism 18, through its own structure and mechanical properties, can maintain the lower inner cylinder 15 as relatively aligned with the axis of the outer cylinder assembly as possible, reducing the degree of deviation between them. This effectively avoids the formation of steps that obstruct core entry due to axis deviation when the core enters the inner cylinder, greatly reducing the possibility of core blockage and improving the success rate of core sampling.

[0097] Coordinated Fluid Circulation: As mentioned above, the third fluid channel 19 inside the inner cylinder straightening mechanism 18 works in conjunction with other fluid channels to optimize the fluid circulation inside the coring device. Good fluid circulation not only provides the necessary cooling, lubrication, and cuttings carrying functions for the drill bit and the entire coring operation, but also plays a crucial role in maintaining the normal working condition of each component of the coring device, further ensuring the smooth progress of the coring operation and improving the quality of the cored samples.

[0098] In summary, this embodiment, through improvements to the structure of the lower inner cylinder 15, the introduction of an inner cylinder straightening mechanism 18, and the provision of corresponding fluid channels, effectively solves the problem of core blockage caused by the swaying and shaking of the inner cylinder assembly during ultra-deep well drilling. It also improves the fluid circulation system of the coring device, providing stronger support for coring devices suitable for ultra-deep wells during coring operations, and helps to improve the efficiency and quality of coring operations.

[0099] Example 9 This embodiment discloses a coring device (hereinafter referred to as "coring device") and a drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, based on embodiment 8, its inner cylinder straightening mechanism 18 includes a straightening sleeve 18.1, an upper connector 18.2 and a lower connector 18.3.

[0100] The upper connector 18.2 includes an integrally formed locking connection part I 18.21 and a sleeve part 18.22. The locking connection part I 18.21 is threadedly fastened to the upper cylinder body, ensuring the stable installation of the upper connector 18.2 in the entire structure and providing a reliable foundation for the connection of subsequent components. The sleeve part 18.22 is a key part that mates with the straightening sleeve 18.1. The straightening sleeve 18.1 is coaxially sleeved on its outside. The inner annular surface of the straightening sleeve 18.1 is fitted with the sleeve part 18.22 with a clearance (1.5mm). This clearance fit allows the straightening sleeve 18.1 to rotate freely relative to the sleeve part 18.22, laying the structural foundation for achieving specific functions.

[0101] Furthermore, its integral construction with cemented carbide endows it with excellent strength and wear resistance, making it less prone to deformation in complex downhole environments and better able to withstand various external forces and wear, thus ensuring its stability and service life. The outer annular surface fits snugly with the inner wall of the outer cylinder assembly (1mm), effectively ensuring the centering effect. This allows the centering sleeve 18.1 to provide good centering for the lower inner cylinder 15 during the coring process. Simultaneously, the centering sleeve 18.1 is equipped with a channel structure for drilling fluid passage. This not only increases the flow area but also improves its erosion resistance, facilitating smooth flow of drilling fluid within the device and reducing the erosive impact of drilling fluid on components.

[0102] The lower connector 18.3 includes an integrally formed locking connection part II 18.31 and a connector connection part 18.32. The locking connection part II 18.31 is threadedly fastened to the sleeve part 18.22, and the lower cylinder 17 is threadedly fastened to the connector connection part 18.32. The outer diameter of both the locking connection part I 18.21 and the lower connector 18.3 is larger than the outer diameter of the straightening sleeve 18.1. This dimensional design plays an important role in connecting the upper cylinder 16 and the lower cylinder 17, as well as limiting the axial displacement of the straightening sleeve 18.1, so that the straightening sleeve 18.1 can be kept in a proper position in the axial direction, ensuring the normal operation of the entire inner cylinder straightening mechanism 18.

[0103] Based on the above structure, the principle by which this technical solution achieves the "dual-barrel single-action" function is as follows: Linkage between the outer cylinder assembly and the centralizing sleeve 18.1: During core drilling, when the outer cylinder assembly rotates, due to the clearance fit between the outer annular surface of the centralizing sleeve 18.1 and the inner wall of the outer cylinder assembly, the outer cylinder assembly can drive the centralizing sleeve 18.1 to rotate synchronously. This rotational linkage is one of the key links to realize subsequent functions.

[0104] The lower inner cylinder 15 remains stationary: Simultaneously, a gap exists between the upper connector 18.2 and the straightening sleeve 18.1, preventing the lower inner cylinder 15 from rotating with the straightening sleeve 18.1 and allowing it to remain stationary. This is because the structural design of the upper connector 18.2 and the clearance fit with the straightening sleeve 18.1 effectively isolate the rotational force of the straightening sleeve 18.1, preventing it from being transmitted to the lower inner cylinder 15.

[0105] The "dual-tube single-action" function is achieved: Through the coordinated action of the outer tube assembly driving the rotation of the centering sleeve 18.1 and the lower inner tube 15 remaining stationary, the "dual-tube single-action" function of inner tube centering and core sampling is simultaneously realized. That is, when the outer tube assembly rotates for core drilling, it can drive the centering sleeve 18.1 to rotate, thereby centering the inner tube, while the lower inner tube 15 remains stationary to better receive and store the core. This functional mode effectively improves the efficiency and quality of core sampling operations and avoids problems such as core damage and blockage caused by unnecessary rotation of the inner tube.

[0106] In summary, the inner cylinder straightening mechanism 18 disclosed in this embodiment, through its unique structural composition and ingenious coordination, not only possesses excellent straightening effect and erosion resistance, but also successfully realizes the "dual-cylinder single-action" function of inner cylinder straightening and coring. This provides strong support for coring devices suitable for ultra-deep wells in coring operations, and helps to improve the overall performance and effect of coring operations.

[0107] Example 10 This embodiment discloses a coring device (hereinafter referred to as "coring device") and a drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, based on Embodiment 9, its channel structure, as an important component of the centralizing sleeve 18.1, plays a crucial role in the flow of drilling fluid within the coring device. It is composed of an inner flow channel 18.11 and an outer flow channel 18.12 respectively disposed on the inner and outer annular surfaces of the centralizing sleeve 18.1. Through reasonable layout and design, smooth flow of drilling fluid inside and outside the centralizing sleeve 18.1 is achieved, thereby affecting the overall operating performance of the coring device. Based on this, the specific layout structure of the inner flow channel 18.11 and the outer flow channel 18.12 is as follows: Several internal flow channels 18.11 are arranged circumferentially along the inner annular surface of the centralizing sleeve 18.1. This circumferentially spaced layout can be distributed relatively evenly on the inner annular surface of the centralizing sleeve 18.1, so that the drilling fluid can have multiple flow paths near the inner annular surface, avoiding local blockage or poor flow.

[0108] Several external flow channels 18.12 are arranged at intervals along the outer annular surface of the centralizing sleeve 18.1. The same circumferentially spaced layout forms a uniformly distributed flow path on the outer annular surface, ensuring that the drilling fluid can flow stably and uniformly near the outer annular surface.

[0109] Example 11 This embodiment discloses a coring device (hereinafter referred to as "coring device") and a drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, based on any one of the embodiments 1 to 10, the core claw assembly includes an annular clamp seat 20 and a core claw body 21.

[0110] The annular clamp seat 20, as part of the core claw assembly, is fastened to the bottom of the inner cylinder assembly by threads, playing an important role in connecting the core claw body 21 and the inner cylinder assembly. It also has a special conical surface 20.1 structure inside, which works in conjunction with the core claw body 21 to achieve functions such as clamping the core.

[0111] The core gripper body 21 is a key component for grasping and holding the core, featuring a variety of unique structural designs to meet its functional requirements. Specifically: The core claw body 21 has an axially penetrating clamping notch 21.1 on one side. This notch has a certain width in the initial state, and its width will change when subjected to external pressure or other forces, thereby realizing the clamping action on the core. This is an important structural basis for the core claw body 21 to effectively grasp the core.

[0112] Near the bottom end of the core body, wedge-shaped locking protrusions 21.2 are spaced circumferentially on the outer wall. These protrusions not only play a key role in the engagement with the annular clamp seat 20, but their wedge-shaped design also helps to achieve better axial positioning when engaging with the conical surface 20.1 of the annular clamp seat 20, and to accurately transmit force when compressed, causing the clamping notch 21.1 to narrow and thus clamp the core.

[0113] A discharge groove 21.3 is provided between adjacent wedge-shaped clamping protrusions 21.2. During core drilling, the drill bit will generate a large amount of rock cuttings when breaking the rock. If these rock cuttings accumulate on the annular clamp, the core claw may not be able to effectively retract and grip the core, leading to problems such as core extraction. The presence of the discharge groove 21.3 can effectively prevent this accumulation of rock cuttings, allowing them to be smoothly discharged through the discharge groove 21.3, ensuring that the core claw body 21 can work normally and achieve effective gripping of the core.

[0114] The core claw body 21 has a clearance fit with the inner wall of the inner cylinder assembly at one end near the top, allowing for circumferential and axial movable connection between the core claw body 21 and the inner cylinder assembly. This movable connection ensures that the core claw body 21 can move freely within a certain range to meet the core grasping requirements during core sampling, while also ensuring its relative positional relationship with the inner cylinder assembly, enabling it to function accurately within the entire core sampling device.

[0115] Based on the above structure, the working principle of this technical solution is as follows: During the core drilling stage, the core claw body 21 is in a relatively relaxed state. At this time, the core continuously enters the inner cylinder assembly under the action of the core drill bit 2, and the clamping notch 21.1 of the core claw body 21 maintains a certain width, allowing the core to smoothly enter the inner cylinder assembly. This is because during the drilling process, the core claw body 21 mainly serves to guide the core into the inner cylinder and does not require clamping the core.

[0116] When the coring device is lifted, the situation changes. Due to its own weight and the friction between the core and the inner cylinder assembly and the core claw body 21, the core tends to move downward relative to the core claw body 21. As the coring device is lifted, the core exerts a downward pulling force on the core claw body 21, causing the core claw body 21 to tend to move downward relative to the annular clamp seat 20.

[0117] Because the tapered surface 20.1, wider at the top and narrower at the bottom, inside the annular clamp seat 20 engages with the wedge-shaped locking protrusion 21.2 of the core claw body 21, when the core claw body 21 moves downward, its wedge-shaped locking protrusion 21.2 slides along the tapered surface 20.1 of the annular clamp seat 20. This sliding process causes the core claw body 21 to be compressed by the tapered surface 20.1, resulting in a narrowing of the clamping notch 21.1. The narrowing of the clamping notch 21.1 allows the core claw body 21 to tightly hold the core, preventing the core from falling out of the inner cylinder assembly during the core extraction process. This ensures that the core can be safely and intactly retrieved from the well, providing high-quality core samples for subsequent geological analysis and other work.

[0118] In summary, the core claw assembly, through its unique structural design and the collaborative working principle of the annular clamp seat 20 and the core claw body 21, can effectively grasp and hold the core, preventing problems such as core detachment during the core sampling process, and providing a strong guarantee for the core sampling device to obtain high-quality core samples.

[0119] Example 12 This embodiment discloses a coring device (hereinafter referred to as "coring device") and a drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, based on embodiment 11, the top of the core claw body 21 is provided with arc-shaped spring plates 21.4 spaced circumferentially along the edge, and these spring plates are bent towards the central axis. This bending shape and orientation design causes the spring plates to exhibit an inward convergence when not subjected to external force, thus structurally preparing for subsequent interaction with the core.

[0120] More specifically, the end face of the arc-shaped spring sheet 21.4 is blade-shaped, with a thickness of less than 1 mm and a width of 10-15 mm. This size design ensures that the spring sheet has a certain degree of elasticity and strength, and allows it to be smoothly opened when the core passes through the core claw body 21 without causing damage to the spring sheet. The thinner thickness helps it to undergo elastic deformation more easily under stress, while the appropriate width ensures a certain range of elasticity and also provides sufficient contact area 15.2 for interaction with the core.

[0121] During core cutting, the core moves downward relative to the core claw body 21. At this time, the arc-shaped spring plate 21.4 rests on the core. Due to the elasticity of the spring plate itself, it undergoes elastic deformation under the compression of the core, generating a reaction force on the core. The direction of this reaction force is to assist in pushing the core claw body 21 downward, thereby causing the core claw body 21 to contract and grip the core.

[0122] During core sampling, several factors can cause the core claw to fail to retract properly. For example, insufficient friction between the core claw body 21 and the core may prevent the core claw body 21 from smoothly retracting downwards as the core moves; or the core claw body 21 may adhere to the inner cylinder assembly, hindering its normal downward retraction. The auxiliary pushing action generated by the arc-shaped spring plate 21.4 can effectively prevent these situations. When the spring plate supports the core and generates a force that pushes the core claw body 21 downwards, even with the aforementioned adverse factors, it can ensure that the core claw body 21 can retract and grip the core relatively smoothly to a certain extent, preventing the problem of cylinder extraction due to incomplete retraction. This ensures that the core can be reliably gripped and completely removed from the well, providing high-quality core samples for subsequent geological analysis and other work.

[0123] In summary, the arc-shaped spring plate 21.4 installed on the core claw body 21 plays an important role in assisting the core claw body 21 to grip the core and avoid problems such as core extraction due to its unique structural features and working principle during core cutting, thereby further improving the reliability of core extraction operations and the quality of core acquisition.

[0124] Example 13 This embodiment discloses a coring device (hereinafter referred to as "coring device") and a drilling coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, based on any one of the embodiments 1 to 12, the outer cylinder assembly includes a differential short section 22 and an outer cylinder body 23 that are coaxially threaded and fastened together.

[0125] In this technical solution, the outer cylinder assembly is constructed by fastening the differential short section 22 and the outer cylinder body 23 together with coaxial threads. This two-section structural design brings many conveniences to the entire coring device, especially in terms of easy assembly and adjustment.

[0126] Based on the above structure, the anti-detachment mechanism 4 and the protective collar 7 can be housed inside the differential sub 22. Placing the anti-detachment mechanism 4 and the protective collar 7 inside the differential sub 22 allows these two components to be relatively concentrated in space, facilitating unified installation and commissioning during the assembly of the coring device. Furthermore, as part of the outer cylinder assembly, the differential sub 22 has a relatively enclosed and stable internal environment, providing better working conditions for the anti-detachment mechanism 4 and the protective collar 7, reducing interference from external factors, and helping to ensure their normal operation and functionality. For example, the anti-detachment mechanism 4 can more stably prevent the inner cylinder assembly from detaching, and the protective collar 7 can more effectively resist the erosion of the outer cylinder in this area by drilling fluid.

[0127] The telescopic adjustment mechanism is located inside the outer cylinder body 23, near the male thread end of the differential short section 22. This location is primarily to account for potential gap adjustment operations later. Its proximity to the male thread end of the differential short section 22 allows operators easy access to the mechanism when adjustments are needed, eliminating the need for extensive disassembly of the entire outer cylinder assembly. This saves adjustment time and labor costs, improving efficiency and convenience. Furthermore, this layout ensures overall coordination between the telescopic adjustment mechanism and other components of the outer cylinder assembly. Its proximity to the male thread end of the differential short section 22 allows for better collaboration with other parts of the outer cylinder assembly, such as the anti-detachment mechanism 4 located inside the differential short section 22. Together, they fulfill various functions of the core-taking device during the core-taking process, such as ensuring the stability of the inner cylinder assembly and adjusting its axial dimensions, thus ensuring smooth core-taking operations.

[0128] In summary, the outer cylinder assembly, by dividing it into differential short sections 22 and the outer cylinder body 23, and rationally arranging components such as the anti-detachment mechanism 4, the protective collar 7, and the telescopic adjustment mechanism, exhibits significant advantages in terms of ease of assembly and adjustment. This provides a strong guarantee for the efficient and stable operation of coring devices suitable for ultra-deep wells, and helps to improve the efficiency and quality of coring operations.

[0129] Example 14 This embodiment discloses a method for assembling a coring device, wherein the coring device is suitable for drilling and coring operations in ultra-deep wells. As a preferred embodiment of the present invention, it includes the following steps: S11. Assemble the outer casing assembly at the coring site. Hoist the assembled outer casing assembly to the target wellhead and use slips to clamp the outer casing assembly. The slips must be evenly distributed and firmly clamp the outer casing assembly to keep it stable at the wellhead position, preventing shaking or displacement during subsequent assembly. This provides a reliable support foundation for the subsequent installation of the inner casing assembly, ensuring the accuracy and safety of the assembly process.

[0130] Assembling the outer cylinder assembly includes coaxially threaded fastening of the differential sub 22 to the outer cylinder body 23, carefully checking the threads at the connection points to ensure the integrity and sealing of the outer cylinder assembly. This step constructs the main structure of the outer cylinder assembly. The tight connection between the differential sub 22 and the outer cylinder body 23 ensures the integrity and stability of the outer cylinder, providing a reliable external framework for the subsequent assembly of the entire coring device. During coring, the outer cylinder assembly needs to withstand enormous pressure, torque, and drilling fluid erosion; its structural stability directly affects the safety and effectiveness of the coring operation.

[0131] S12, perform the inner cylinder assembly assembly operation above the outer cylinder assembly, and axially connect the shock absorption assembly 3 to the top of the inner cylinder assembly. Place the assembled inner cylinder assembly into the outer cylinder assembly, and axially limit it through the anti-detachment mechanism 4 to prevent the inner cylinder assembly from detaching from the outer cylinder assembly.

[0132] S13, fasten the upper connector 1 to the top of the outer cylinder assembly via threads. At this time, the upper connector 1 covers the vibration damping assembly and is clearance-fitted with the vibration damping assembly.

[0133] S14, using a lifting sub, the assembled coring device is pulled out of the target well as a whole.

[0134] S15, Install the core claw assembly at the bottom of the inner cylinder assembly.

[0135] S16, Install the core drill bit 2 at the bottom of the outer cylinder assembly.

[0136] Example 15 This embodiment discloses an assembly method for a core-taking device. As a preferred embodiment of the present invention, based on embodiment 14, step S12 of the inner cylinder assembly operation includes the following steps: S121, complete the assembly operation of the lower inner cylinder 15. Use the inner cylinder chuck to place the lower inner cylinder 15 on the end face of the outer cylinder assembly to initially determine the relative positional relationship between the lower inner cylinder 15 and the outer cylinder assembly, so as to facilitate subsequent connection and debugging operations.

[0137] The assembly of the lower inner cylinder 15 includes: assembling the inner cylinder straightening mechanism 18, that is, coaxially sleeve the straightening sleeve 18.1 on the outside of the sleeve portion 18.22 of the upper connector 18.2, then threadedly fastening the locking connection portion II 18.31 of the lower connector 18.3 to the sleeve portion 18.22; threadedly fastening the locking connection portion I 18.21 of the upper connector 18.2 to the upper cylinder 16; and threadedly fastening the lower cylinder 17 below the connector connection portion 18.32 of the lower connector 18.3.

[0138] S122, in the inner cylinder assembly area, the ball seat 10 is coaxially and securely connected to the bottom of the upper spindle 9, and the second fluid channel 11 inside the ball seat 10 is checked to ensure it is unobstructed.

[0139] S123, make an adjustable threaded connection between the upper internal thread 12.1 of the hollow part of the adjusting nut 12 and the upper spindle 9. By rotating the adjusting nut 12, initially adjust its axial position so that it is approximately in a suitable height range (preset position).

[0140] S124. Select a polygonal retaining ring 13 with an appropriate thickness and embed it between the ball seat 10 and the adjusting nut 12, so that the inner wall of the polygonal retaining ring 13 is in clearance fit with the middle retaining ring mating part 10.3 of the ball seat 10, and the outer wall is in clearance fit with the polygonal through hole 12.3 of the adjusting nut 12. It is necessary to ensure that the polygonal retaining ring 13 and the polygonal through hole 12.3 of the adjusting nut 12 can fit tightly to prevent the adjusting nut 12 from rotating.

[0141] S125, tighten the locking nut 14 to the lower threaded part 10.4 of the ball seat 10, axially fix the polygonal snap ring 13 to prevent the adjusting nut 12 from rotating, and complete the preliminary construction of the structure related to the axial dimension adjustment of the inner cylinder assembly, thereby completing the preliminary installation and debugging of the telescopic adjustment mechanism.

[0142] S126, the protective collar 7 is fitted into the differential short section 22, and the locking step 8 on the inner wall of the outer cylinder assembly prevents the protective collar 7 from falling; then the anti-detachment mechanism 4 is fitted onto the upper mandrel 9, and the top of the protective collar 7 serves as the lower limiting step 4.4 inside the outer cylinder assembly, which can prevent the protective collar 7 from falling. The overall layout of each component in the entire coring device structure is gradually improved.

[0143] S127 After installing the shock absorption assembly 3 onto the upper spindle 9, hoist the upper spindle 9 to the top of the lower inner cylinder 15, and then fasten the top of the lower inner cylinder 15 to the adjusting nut 12 at the bottom of the upper spindle 9. This completes the overall assembly of the core extractor.

[0144] Example 16 This embodiment discloses an assembly method for a core-taking device. As a preferred embodiment of the present invention, based on embodiment 15, step S127, which involves installing the shock-absorbing assembly 3 onto the upper mandrel 9, includes the following steps: S1271, the damping disc spring 3.1 is coaxially placed into the connecting tube structure 3.32 of the damping seat 3.3.

[0145] S1272, insert the top of the inner cylinder assembly into the connecting cylinder structure 3.32, and compress and pre-tighten the damping disc spring 3.1 in conjunction with the base structure 3.31 of the damping seat 3.3.

[0146] S1273, locating pins 3.2 are screwed into all the locating holes 3.4 of the shock absorber 3.3 one by one. After the locating pins 3.2 pass through the locating holes 3.4, they are inserted into the straight waist hole 3.5 on the inner cylinder assembly, so that the inner cylinder assembly is axially connected to the shock absorber 3.3.

[0147] Example 17 This embodiment discloses an assembly method for a core-taking device. As a preferred embodiment of the present invention, based on embodiments 14, 15, or 16, it further includes step S17, namely: S171, check whether the gap between the inner step 2.1 of the core drill bit 2 and the core claw assembly is within the range of 5 mm to 15 mm; if not, proceed to step S172; if yes, proceed directly to step S176.

[0148] S172, separate the differential section 22 from the outer cylinder body 23, and lift the differential section 22 and the inner cylinder assembly together to expose the telescopic adjustment mechanism.

[0149] S173, after removing the lower inner cylinder 15 from the adjusting nut 12 of the telescopic adjustment mechanism, remove the locking nut 14 and the polygonal snap ring 13 from the ball seat 10 in sequence.

[0150] S174, after adjusting the position of the adjusting nut 12 on the upper spindle 9 by rotating, the polygonal snap ring 13 and the locking nut 14 are reinstalled on the ball seat 10 in sequence.

[0151] S175, after reconnecting the lower inner cylinder 15 to the adjusting nut 12, lower the inner cylinder assembly and the differential short section 22 together, and reconnect the differential short section 22 to the outer cylinder body 23, then return to step S171.

[0152] S176, no adjustment of the axial dimension of the inner cylinder assembly is required.

[0153] Example 18 This embodiment discloses a drilling and coring method suitable for ultra-deep wells. As a preferred embodiment of the present invention, drilling and coring are performed using any one of the coring devices suitable for ultra-deep wells in embodiments 1 to 13, including the following steps: S21. After completing the assembly of the coring device, connect it to the bottom of the drill string of the upper drill string and perform the drilling operation according to the drilling operation procedures. During this process, considering the strong compaction of the formation in ultra-deep wells, it is often necessary to match the downhole motor such as the screw to achieve efficient drilling. Therefore, a hydraulic or electrically controlled ball dropping device should be matched to the upper end of the upper connector 1 to achieve effective flushing and setting of the inner cylinder, and to avoid the inability to drop balls when assembling the screw.

[0154] Furthermore, during the drilling operation, when the coring device enters the open hole section, a short trip trip is performed. At the same time, drilling data, including the suspended weight and drilling pressure during the lifting and lowering of the coring device, are recorded. This data will provide important reference for the subsequent correction of coring drilling parameters and help to optimize the drilling process according to the actual situation.

[0155] S22, after-effect removal operation is performed. During this process, drilling fluid is introduced into the coring device through the upper drill string, flowing sequentially through the upper connector 1, shock absorption assembly 3, inner cylinder assembly, and core claw assembly, finally reaching the coring bit 2. The coring bit 2 is cooled, cleaned, and lubricated, while carrying rock cuttings back to the surface through the wellbore annulus. When the coring bit 2 of the coring device is 2-3 drill pipes away from the bottom of the well, the top drive drilling device is connected to the upper drill string, and a circulation lowering operation is performed, using a light pressure and slow rotation method to ream the coring device to the bottom.

[0156] In drilling operations, "circulation to eliminate aftereffects" primarily refers to the process of eliminating the subsequent impacts of complex downhole conditions through drilling fluid circulation at specific stages of the drilling operation. When the drill bit reaches a certain depth or after operations such as tripping in and out of the well, conditions such as formation pressure and temperature around the wellbore change. These changes can lead to potential problems, such as the intrusion of formation fluids (oil, gas, water) into the drilling fluid, or changes in the drilling fluid's properties due to formation materials. Circulation to eliminate aftereffects removes these adverse effects by circulating the drilling fluid. Typically, drilling equipment is used to circulate the drilling fluid within the wellbore. The drilling fluid is pumped from the mud pit at the surface into the drill string, passes through the drill bit, returns to the surface through the annulus (the space between the drill string and the wellbore), and then flows back to the mud pit, repeating this cycle. During circulation, new drilling fluid continuously replaces the affected drilling fluid in the wellbore, carrying formation fluids, cuttings, and other impurities from near the wellbore to the surface, restoring the normal properties of the drilling fluid within the wellbore.

[0157] Top drive drilling rig is an advanced piece of equipment used in oil drilling. It is installed on the top of the derrick of the drilling platform and uses a rotatable drive mechanism to directly apply torque to the drill string above, thereby driving the core retrieval device (core bit 2) to rotate for drilling operations.

[0158] "Circulation and lowering": "Circulation" refers to the circulation of drilling fluid, and "lowering" refers to the lowering of the coring tool. In other words, "circulation and lowering" means maintaining the circulation of drilling fluid while the drill string is moving (lowering) to the bottom of the well.

[0159] Light pressure and slow rotation: "Pressure" refers to drilling pressure, and "rotation" refers to rotational speed. "Light pressure and slow rotation" means using a smaller downward pressure and a lower rotational speed during the cyclic lowering process.

[0160] Reaming refers to using a drill bit to re-cut a regular wellbore into the well wall.

[0161] S23, steel balls are inserted into the inner cylinder device to seal the inner cylinder assembly. The steel balls sit on the ball seat 10 and cooperate with the ball seat 10 to seal the inner cylinder assembly.

[0162] S24, coping drilling begins. During drilling, drilling fluid is introduced into the coping device through the upper drill string, flowing sequentially through the upper connector 1 and the shock absorption assembly 3. It then enters the annular structure 5 between the inner and outer cylinder assemblies through the flow channel 6 of the inner cylinder assembly. The fluid then reaches the coping bit 2 through the annular structure 5, where it is cooled, cleaned, and lubricated. Simultaneously, it carries rock cuttings back to the surface through the wellbore annulus. Once the predetermined coping length is reached, the coping operation is completed.

[0163] Furthermore, during the core cutting operation, when the pulling force exceeds 50kN, lower the core extractor to its original suspended weight; start the top drive drilling unit and set the core extractor's rotation speed within the range of 20~50rpm; then use the reverse reaming method to raise the core extractor until the core is raised to the wellbore. When extracting the core, the wellhead operation time should be controlled as much as possible to avoid prolonged empty wellbore operation, which could cause downhole complications.

Claims

1. A coring device suitable for ultra-deep wells, characterized in that: It includes an upper connector (1), an inner cylinder assembly, an outer cylinder assembly, a core claw assembly, a core drill bit (2), and a shock absorption assembly (3). The shock absorption assembly (3) is coaxially and movably embedded inside the upper connector (1) and located at one end near the bottom of the upper connector (1). A first fluid channel (3.6) is axially provided inside it. The inner cylinder assembly is coaxially disposed inside the outer cylinder assembly and is axially limited to the outer cylinder assembly through the anti-detachment mechanism (4); an annular structure (5) is reserved between the inner cylinder assembly and the outer cylinder assembly, and several flow channel holes (6) communicating with the annular structure (5) are opened on the inner cylinder assembly. The top of the outer cylinder assembly is screwed and fastened to the upper connector (1), and the core drill bit (2) is coaxially fixed to the bottom of the outer cylinder assembly; The top of the inner cylinder assembly is axially movable to the shock absorption assembly (3); the core claw assembly is coaxially disposed inside the core drill bit (2) and is fixedly connected to the bottom of the inner cylinder assembly.

2. The coring device for ultra-deep wells as described in claim 1, characterized in that: The damping assembly (3) includes a damping seat (3.3), a damping disc spring (3.1), and several locating pins (3.2). The shock absorber (3.3) is fitted with the upper connector (1) with a clearance, and includes an integrally formed base structure (3.31) and a connecting cylinder structure (3.32). The connecting cylinder structure (3.32) is provided with a number of positioning holes (3.4) at intervals in the circumferential direction. The top of the inner cylinder assembly is inserted into the connecting cylinder structure (3.32) of the shock absorber (3.3) and is clearance-fitted with the connecting cylinder structure (3.32); at one end of the inner cylinder assembly near the top, there are several straight waist holes (3.5) that correspond one-to-one with the positioning holes (3.4) and extend axially; after all the positioning pins (3.2) pass through the positioning holes (3.4) one-to-one, they are inserted into the corresponding straight waist holes (3.5), so that the inner cylinder assembly and the shock absorber (3.3) are axially movable. The damping disc spring (3.1) is coaxially disposed in the connecting cylinder structure (3.32) of the damping seat (3.3), and after being compressed, it is snapped between the base structure (3.31) and the inner cylinder assembly.

3. The coring device for ultra-deep wells as described in claim 1, characterized in that: The anti-detachment mechanism (4) includes a bearing component (4.1); the bearing component (4.1) is coaxially sleeved on the inner cylinder assembly, the outer wall of the inner cylinder assembly is provided with an upper limiting step (4.3), the inner wall of the outer cylinder assembly is provided with a lower limiting step (4.4), and the bearing component (4.1) is located between the upper limiting step (4.3) and the lower limiting step (4.4); the upper limiting step (4.3) and the lower limiting step (4.4) cooperate to restrict the axial movement of the bearing component (4.1).

4. The coring device for ultra-deep wells as described in claim 1, characterized in that: Inside the outer cylinder assembly, a protective collar (7) is provided at the position corresponding to the flow channel hole (6); the protective collar (7) is tightly fitted to the inner wall of the outer cylinder assembly, and the outer cylinder assembly is provided with a locking step (8) to prevent the protective collar (7) from moving axially.

5. The coring device for ultra-deep wells as described in claim 1, characterized in that: The inner cylinder assembly includes an upper spindle (9), a ball seat (10), a telescopic adjustment mechanism, and a lower inner cylinder (15). The ball seat (10) is coaxially disposed inside the telescopic adjustment mechanism and is coaxially and sealed to the upper spindle (9); a second fluid channel (11) is axially disposed inside the ball seat (10). The lower inner cylinder (15) is coaxially arranged with the upper spindle (9) and is axially adjustable and fastened to the upper spindle (9) through a telescopic adjustment mechanism.

6. The coring device for ultra-deep wells as described in claim 5, characterized in that: The telescopic adjustment mechanism includes an adjustment nut (12), a multi-sided snap ring (13), and a locking nut (14). The adjusting nut (12) is hollow and includes an integrally formed upper internal threaded part (12.1) and a lower external threaded part (12.2). The upper internal threaded part (12.1) is adjustablely threaded to the upper spindle (9), and the lower external threaded part (12.2) is threadedly fastened to the lower inner cylinder (15). A polygonal through hole (12.3) is provided at the center of the lower external threaded part (12.2). The ball seat (10) includes an upper ball support part, a middle retaining ring fitting part (10.3) and a lower screw part (10.4) that are coaxially integrally formed. The upper ball support part is fastened to the inner wall of the upper spindle (9). The polygonal snap ring (13) is embedded between the ball seat (10) and the adjusting nut (12). Its inner wall is in clearance fit with the middle snap ring fitting part (10.3) of the ball seat (10), and its outer wall is in clearance fit with the polygonal through hole (12.3) of the adjusting nut (12). The locking nut (14) is fitted with the lower screw part (10.4) of the ball seat (10) to fix the polygonal snap ring (13) axially.

7. The coring device for ultra-deep wells as described in claim 5, characterized in that: On the inner wall of the lower inner cylinder (15), a number of straight chip discharge grooves (15.1) are provided at intervals along the circumference, and the straight discharge grooves (21.3) extend axially to penetrate the entire lower inner cylinder (15).

8. The coring device for ultra-deep wells as described in claim 7, characterized in that: The cross-section of the straight chip removal groove (15.1) is trapezoidal.

9. The coring device for ultra-deep wells as described in claim 5, characterized in that: The lower inner cylinder (15) includes an upper cylinder (16) and a lower cylinder (17) arranged coaxially, and an inner cylinder straightening mechanism (18) is connected between the upper cylinder (16) and the lower cylinder (17). A third fluid channel (19) is axially arranged inside the inner cylinder straightening mechanism (18).

10. The coring device for ultra-deep wells as described in claim 9, characterized in that: The inner cylinder straightening mechanism (18) includes a straightening sleeve (18.1), an upper connector (18.2), and a lower connector (18.3). The upper connector (18.2) includes an integrally formed locking connection part I (18.21) and a sleeve part (18.22); the locking connection part I (18.21) is threadedly fastened to the upper cylinder (16); The centralizing sleeve (18.1) is coaxially sleeved on the outside of the casing section (18.22), with its inner annular surface in clearance fit with the casing section (18.22) and its outer annular surface in clearance fit with the inner wall of the outer cylinder assembly; the centralizing sleeve (18.1) is provided with a channel structure for drilling fluid to pass through; The lower connector (18.3) includes an integrally formed locking connection part II (18.31) and a connector connection part (18.32); the locking connection part II (18.31) is threadedly fastened to the sleeve part (18.22), and the lower cylinder (17) is threadedly fastened to the connector connection part (18.32).

11. The coring device for ultra-deep wells as described in claim 10, characterized in that: The channel structure includes several inner flow channels (18.11) spaced circumferentially along the inner annular surface of the straightening sleeve (18.1) and outer flow channels (18.12) spaced circumferentially along the outer annular surface of the straightening sleeve (18.1).

12. The coring device for ultra-deep wells as described in claim 1, characterized in that: The core claw assembly includes an annular clamp seat (20) and a core claw body (21). The core claw body (21) has an axially penetrating notch (21.1) on one side; the core body has wedge-shaped locking protrusions (21.2) spaced apart circumferentially at one end near the bottom, and a discharge groove (21.3) is formed between adjacent wedge-shaped locking protrusions (21.2); the core claw body (21) is in clearance fit with the inner wall of the inner cylinder assembly at one end near the top, so that the core claw body (21) and the inner cylinder assembly are circumferentially and axially movable; The annular clamp seat (20) is threadedly fastened to the bottom of the inner cylinder assembly. The annular clamp seat (20) has a tapered surface (20.1) that is wider at the top and narrower at the bottom. The tapered surface (20.1) is wedge-shapedly engaged with the wedge-shaped locking protrusion (21.2) of the core claw body (21).

13. The coring device for ultra-deep wells as described in claim 1, characterized in that: The top of the core claw body (21) is provided with arc-shaped spring plates (21.4) that bend toward the central axis at intervals along the edge.

14. The coring device for ultra-deep wells as described in claim 1, characterized in that: The outer cylinder assembly includes a differential short section (22) and an outer cylinder body (23) that are coaxially threaded and fastened together.

15. A method for assembling a core-taking device, characterized in that, Includes the following steps: S11, Assemble the outer cylinder assembly at the coring site, hoist the outer cylinder assembly to the target wellhead, and then use slips to clamp the outer cylinder assembly; S12, perform inner cylinder assembly assembly operation above outer cylinder assembly, and axially connect shock absorption assembly (3) to the top of inner cylinder assembly to place the assembled inner cylinder assembly into outer cylinder assembly, and axially limit it through anti-detachment mechanism (4) to prevent inner cylinder assembly from detaching from outer cylinder assembly; S13, fasten the upper connector (1) to the top of the outer cylinder assembly through the thread. At this time, the upper connector (1) covers the vibration damping assembly and is in clearance fit with the vibration damping assembly. S14, using a lifting sub to extract the assembled coring device from the target well as a whole; S15, Install the core claw assembly at the bottom of the inner cylinder assembly; S16, install the core drill bit (2) at the bottom of the outer cylinder assembly.

16. The assembly method of the core-taking device as described in claim 15, characterized in that, In step S11, assembling the outer cylinder assembly includes coaxially threading the difference short section (22) to the outer cylinder body (23).

17. A method for assembling a core-taking device as described in claim 16, characterized in that, In step S12, the inner cylinder assembly operation includes the following steps: S121, After assembling the lower inner cylinder (15), use the inner cylinder chuck to place the lower inner cylinder (15) on the end face of the outer cylinder assembly; S122, the ball seat (10) is coaxially and securely connected to the bottom of the upper spindle (9); S123, rotate the adjusting nut (12) and the bottom of the upper spindle (9) by threading, so that the adjusting nut (12) is rotated to the preset position of the upper spindle (9); S124, Select a polygonal snap ring (13) with a suitable thickness and fit the polygonal snap ring (13) onto the middle snap ring mating part (10.3) of the ball seat (10) to ensure that the polygonal snap ring (13) and the polygonal through hole (12.3) of the adjusting nut (12) can fit tightly; S125, the locking nut is threadedly fastened to the lower threaded part (10.4) of the ball seat (10) to axially fix the polygonal snap ring (13); S126, insert the protective collar (7) into the differential short section (22), and then put the anti-detachment mechanism (4) onto the upper spindle (9); S127 After installing the shock absorber assembly (3) onto the upper spindle (9), tighten the top of the lower inner cylinder (15) to the adjusting nut (12) at the bottom of the upper spindle (9).

18. A method for assembling a core-taking device as described in claim 17, characterized in that, In step S121, assembling the lower inner cylinder (15) includes the following steps: Assemble the inner cylinder straightening mechanism (18), that is, coaxially sleeve the straightening sleeve (18.1) on the outside of the sleeve part (18.22) of the upper connector (18.2), and then thread the locking connection part II (18.31) of the lower connector (18.3) to the sleeve part (18.22). The locking connection part I (18.21) of the upper connector (18.2) is threadedly fastened to the upper cylinder (16); The lower cylinder (17) of the lower connector (18.3) is fastened to the threaded connection of the connector connection part (18.32).

19. A method for assembling a core-taking device as described in claim 17, characterized in that, In step S127, installing the shock absorber assembly (3) onto the upper spindle (9) includes the following steps: S1271, the damping disc spring (3.1) is coaxially placed into the connecting tube structure (3.32) of the damping seat (3.3); S1272, insert the top of the inner cylinder assembly into the connecting cylinder structure (3.32), and use the base structure (3.31) of the shock absorber seat (3.3) to compress and pre-tighten the damping disc spring (3.1); S1273, locating pins (3.2) are screwed into all the locating holes (3.4) of the shock absorber (3.3) one by one. After the locating pins (3.2) pass through the locating holes (3.4), they are inserted into the straight waist hole (3.5) on the inner cylinder assembly, so that the inner cylinder assembly is axially connected to the shock absorber (3.3).

20. A method for assembling a core-taking device as described in claim 17, characterized in that: It also includes step S17, namely: S171, check whether the gap between the inner step (2.1) of the core drill bit (2) and the core claw assembly is within the range of 5 mm to 15 mm; if not, proceed to step S172; if yes, proceed directly to step S176. S172, separate the differential short section (22) from the outer cylinder body (23), and lift the differential short section (22) and the inner cylinder assembly together to expose the telescopic adjustment mechanism; S173, after removing the lower inner cylinder (15) from the adjusting nut (12) of the telescopic adjustment mechanism, remove the locking nut (14) and the polygonal snap ring (13) from the ball seat (10) in sequence; S174, after adjusting the position of the adjusting nut (12) on the upper spindle (9) by rotating, reinstall the polygonal snap ring (13) and the locking nut (14) onto the ball seat (10) in sequence; S175, after reconnecting the lower inner cylinder (15) to the adjusting nut (12), lower the inner cylinder assembly and the differential short section (22) together, and reconnect the differential short section (22) to the outer cylinder body (23), and return to step S171; S176, no adjustment of the axial dimension of the inner cylinder assembly is required.

21. A drilling and coring method suitable for ultra-deep wells, characterized in that, Core drilling using a core sampling device suitable for ultra-deep wells as described in any one of claims 1 to 14 includes the following steps: S21. After completing the assembly of the coring device, connect the coring device to the bottom of the drill string of the upper drill string and carry out the drilling operation in accordance with the drilling operation procedures. S22, perform cyclic removal of aftereffects; during this period, when the core bit (2) of the core sampling device is still 2 to 3 drill pipes away from the bottom of the well, connect the top drive drilling device in the upper drill string and perform cyclic lowering operation, and use light pressure and slow rotation to make the core sampling device drill to the bottom. S23, steel balls are inserted into the inner cylinder device to seal the inner cylinder assembly; S24, start the coring drilling operation. When the coring drilling reaches the predetermined coring length, the coring operation is completed.

22. The drilling and coring method for ultra-deep wells as described in claim 21, characterized in that: During the drilling operation in step S21, when the coring device enters the open hole section, a short trip tripping operation is performed. At the same time, drilling data including the suspended weight and drilling pressure during the lifting and lowering of the coring device are recorded.

23. The drilling and coring method for ultra-deep wells as described in claim 21, characterized in that: During the core cutting operation in step 24, when the lifting force exceeds 50kN, the core extractor is lowered to its original suspended weight; the top drive drilling device is started, and the rotation speed of the core extractor is set in the range of 20~50rpm; then the core extractor is raised using the reverse reaming method until the core is raised to the wellbore.

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