Pressure maintaining coring pressurizing mechanism

Abstract

The application relates to a pressure-keeping coring pressurizing mechanism, which comprises a pressurizing inner cylinder, a pressurizing outer cylinder sleeved on the outer side of the pressurizing inner cylinder, a steel ball for axially locking the pressurizing outer cylinder and the pressurizing inner cylinder and an unlocking mechanism for unlocking the axial locking, the steel ball can be simultaneously arranged in the cylinder wall of the pressurizing inner cylinder and the pressurizing outer cylinder to realize the axial locking; the unlocking mechanism comprises an unlocking sleeve arranged in the pressurizing inner cylinder, the unlocking is realized by sliding the unlocking sleeve downward relative to the pressurizing inner cylinder, when the unlocking sleeve is located at an unlocking position, the steel ball is withdrawn from the cylinder wall of the pressurizing outer cylinder and is simultaneously arranged in the cylinder wall of the unlocking sleeve and the pressurizing inner cylinder, so that the axial locking is released; when the axial locking is released, the pressurizing outer cylinder can be moved downward from a first position to a second position relative to the pressurizing inner cylinder. The application uses the sliding of the unlocking sleeve to realize the unlocking, which is safer than the pure pin fixing; the pressurizing mechanism can realize the bidirectional movement actions of pressing the core claw downward to cut the core and lifting the core cabin upward to keep the pressure.

Description

Technical Field

[0001] This invention relates to the field of pressure-holding coring technology, and more particularly to a pressure-holding coring mechanism. Background Technology

[0002] Deep oil and gas low-disturbance, heat-preserving, and pressure-preserving coring technology is a coring technique that ensures the extracted core remains at its original formation pore water pressure, temperature, and state. This is mainly achieved through the coordinated operation of pressure-preserving assemblies, heat-preserving assemblies, anti-rotation assemblies, and pressurizing assemblies.

[0003] When performing pressurized coring in loose formations, the pressurization method typically involves using a ball-dropping technique to build up pressure and shear the starting pin, then applying pressure to the core barrel and core claw to force them downwards, ultimately causing the core claw to contract and cut the core. However, because drilling fluid circulation is not stable and fluctuates due to pump pressure, the drilling fluid can experience impacts, potentially causing the pin to shear prematurely. This method, relying solely on pin fixation, is not safe enough. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a pressure-holding coring mechanism.

[0005] This invention is achieved through the following technical solution: This application provides a pressure-holding coring mechanism, comprising a pressure-holding inner cylinder, a pressure-holding outer cylinder with its upper end sleeved outside the pressure-holding inner cylinder, a steel ball for axially locking the pressure-holding outer cylinder and the pressure-holding inner cylinder, and an unlocking mechanism for releasing the axial lock between the pressure-holding outer cylinder and the pressure-holding inner cylinder. The steel ball can be simultaneously installed in the cylinder walls of both the pressure-holding inner cylinder and the pressure-holding outer cylinder to achieve the axial lock. The unlocking mechanism includes an unlocking sleeve installed inside the pressure-holding inner cylinder, which has a locking position and an unlocking position. By sliding the unlocking sleeve downward relative to the pressure-holding inner cylinder, the unlocking sleeve switches from the locking position to the unlocking position. When the unlocking sleeve is in the unlocking position, the steel ball exits from the cylinder wall of the pressure-holding outer cylinder and is simultaneously installed in the cylinder walls of both the unlocking sleeve and the pressure-holding inner cylinder, thereby releasing the axial lock. When the axial lock is released, the pressure-holding outer cylinder can move downward relative to the pressure-holding inner cylinder from a first position to a second position.

[0006] Optionally, a steel ball is installed in a hole on the wall of the pressurized inner cylinder, and the diameter of the steel ball is larger than the wall thickness of the pressurized inner cylinder; the inner wall of the pressurized outer cylinder has an annular inner groove that matches the steel ball. When the pressurized outer cylinder is in the first position, part of the steel ball is installed in the pressurized inner cylinder, and the other part of the steel ball is installed in the annular inner groove on the inner wall of the pressurized outer cylinder. The pressurized inner cylinder is axially fixed to the pressurized outer cylinder and can rotate circumferentially through the steel ball.

[0007] Optionally, the outer wall of the unlocking sleeve has an annular outer groove that matches the steel ball on the pressurized inner cylinder; when the unlocking sleeve is in the unlocked position, the annular outer groove on the unlocking sleeve is aligned with the steel ball on the pressurized inner cylinder, and the steel ball can exit from the annular inner groove of the pressurized outer cylinder and enter the annular outer groove of the unlocking sleeve, thereby releasing the axial lock.

[0008] Optionally, the unlocking mechanism further includes an unlocking ball, and the unlocking sleeve is fixed in the pressurized inner cylinder by an unlocking pin, at which time the unlocking sleeve is in the locked position; the unlocking sleeve has an internal flow channel, and the top of the unlocking sleeve has a conical ball seat adapted to the unlocking ball; the outer wall of the unlocking sleeve has a first water passage hole, which penetrates the internal flow channel of the unlocking sleeve and is located below the conical ball seat; the unlocking ball is configured to block the top opening of the internal flow channel of the unlocking sleeve when it is placed in the conical ball seat.

[0009] Optionally, the outer wall of the pressurized inner cylinder has a first limiting step, and the outer wall of the pressurized outer cylinder has a second limiting step adapted to the first limiting step, which is located above the first limiting step. When the first limiting step and the second limiting step abut against each other, the pressurized outer cylinder cannot move downward relative to the pressurized inner cylinder.

[0010] Optionally, a pressure-holding core-taking mechanism further includes a spring, under the action of the spring, the pressure-holding outer cylinder tends to move downward from a first position to a second position relative to the pressure-holding outer cylinder.

[0011] Optionally, a pressure-holding coring mechanism further includes a differential mechanism, which includes a differential inner tube, a differential outer tube, a differential ball seat, and a differential ball. The lower end of the differential inner tube is connected to the differential ball seat, which has a flow channel hole and a sealing surface adapted to the differential ball. The lower end of the differential outer tube is connected to the pressure-pressurizing inner cylinder, and a second water passage hole adapted to the first water passage hole is located at a corresponding position on the side wall of the differential outer tube. When the unlocking sleeve is in the locked position, the medium can flow from the internal flow channel of the pressure-pressurizing inner cylinder through the first water passage hole and the second water passage hole to the outside of the differential outer tube.

[0012] Optionally, the differential outer tube has a first pressure relief hole located above the differential ball seat; one of the differential inner tube and the differential outer tube has a serrated retaining spring, and the other has a safety claw that matches the serrated retaining spring; when the differential outer tube moves upward relative to the differential inner tube to a certain height, the safety claw can lock onto the serrated retaining spring, at which point the differential outer tube cannot move downward relative to the differential inner tube.

[0013] Optionally, a pressure-holding coring mechanism further includes a pressure-relieving sleeve, which is fixed in the differential outer tube by a safety pin. The upper end of the unlocking sleeve is installed in the pressure-relieving sleeve, and the lower end of the unlocking sleeve is installed in the pressure-pressurizing inner tube. The pressure-relieving sleeve is located between the unlocking sleeve and the differential outer tube. The differential outer tube has a second pressure-relieving hole at a position corresponding to the pressure-relieving sleeve. When the pressure-relieving sleeve is fixed to the differential outer tube by the safety pin, the second pressure-relieving hole is blocked by the pressure-relieving sleeve, and the medium cannot flow to the outside of the differential outer tube through the second pressure-relieving hole. When the safety pin between the pressure-relieving sleeve and the differential outer tube is hydraulically sheared, the pressure-relieving sleeve can move downward relative to the differential outer tube. When the pressure-relieving sleeve moves downward to a predetermined position, the second pressure-relieving hole on the differential outer tube is exposed, and the medium can flow to the outside of the differential outer tube through the second pressure-relieving hole.

[0014] Optionally, the differential outer tube has a limiting step adapted to the pressure relief sleeve. When the pressure relief sleeve descends to the point where it abuts against the limiting step, the pressure relief sleeve descends to the predetermined position and cannot continue to move downward relative to the differential outer tube.

[0015] Compared with the prior art, this application has at least the following beneficial effects: 1. This application utilizes the sliding of the unlocking sleeve to unlock, which is safer than pure pin fixing; 2. The pressurization mechanism of this application can realize bidirectional movement of the lower core claw for core cutting and the upper core extraction chamber for pressure maintenance.

[0016] Of course, implementing any of the embodiments of the present invention does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the pressure-holding and coring mechanism in the embodiment when the pressure-pressurized outer cylinder is in the first position; Figure 2 This is a schematic diagram of the pressure-holding and coring mechanism when the pressure-pressurized outer cylinder is in the second position in the embodiment. Figure 3 This is a schematic diagram of the core-taking device in the embodiment. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. It should also be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments; similar or identical parts between embodiments can be referred to interchangeably.

[0021] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] like Figure 1 As shown, this embodiment discloses a preferred pressure-holding coring mechanism, including a pressure inner cylinder 51, a pressure outer cylinder 52, a steel ball 56 for axially locking the pressure outer cylinder 52 and the pressure inner cylinder 51, and an unlocking mechanism for releasing the axial lock between the pressure outer cylinder 52 and the pressure inner cylinder 51. The upper end of the pressure outer cylinder 52 is sleeved outside the pressure inner cylinder 51. The steel ball 56 can be simultaneously installed in the cylinder walls of both the pressure inner cylinder 51 and the pressure outer cylinder 52 to achieve the axial lock. The unlocking mechanism is used to remove the steel ball 56 from the cylinder wall of the pressure outer cylinder 52 to release the axial lock. When the axial lock is released, the pressure outer cylinder 52 can move downward relative to the pressure inner cylinder 51 from a first position to a second position, thereby achieving downward pressure through the downward movement of the pressure outer cylinder 52.

[0024] In some embodiments, a steel ball 56 is installed in a hole on the wall of the pressurized inner cylinder 51, and the diameter of the steel ball 56 is larger than the wall thickness of the pressurized inner cylinder 51. The inner wall of the pressurized outer cylinder 52 has an annular inner groove 521 adapted to the steel ball 56. When the pressurized outer cylinder 52 is in the first position, part of the steel ball 56 is installed in the pressurized inner cylinder 51, and the other part of the steel ball 56 is installed in the annular inner groove 521 on the inner wall of the pressurized outer cylinder 52. The pressurized inner cylinder 51 is axially fixed to the pressurized outer cylinder 52 by the steel ball 56, and the pressurized inner cylinder 51 and the pressurized outer cylinder 52 can also rotate circumferentially by the steel ball 56.

[0025] Preferably, the unlocking mechanism includes an unlocking sleeve 53 installed inside the pressurized inner cylinder 51. The outer wall of the unlocking sleeve 53 has an annular outer groove 532 that matches the steel ball 56 on the pressurized inner cylinder 51. The unlocking sleeve 53 has a locking position and an unlocking position, such as... Figure 1 As shown, when the unlocking sleeve 53 is in the locked position, the pressure outer sleeve 52 is in the first position; as Figure 2 As shown, when the unlocking sleeve 53 is in the unlocked position, the annular outer groove 532 on the unlocking sleeve 53 is aligned with the steel ball 56 of the pressurized inner cylinder 51. The steel ball 56 can exit from the annular inner groove 521 of the pressurized outer cylinder 52 and enter the annular outer groove 532 of the unlocking sleeve 53, thereby releasing the axial lock. At this time, the pressurized outer cylinder 52 can move downward from the first position to the second position relative to the pressurized inner cylinder 51.

[0026] It is worth noting that the axial sliding distance of the unlocking sleeve 53 relative to the pressurized inner cylinder 51 is controlled by the axial dimension of the annular outer groove 532. When the steel ball 56 abuts against the top of the annular outer groove 532, the unlocking sleeve 53 cannot slide downward relative to the pressurized inner cylinder 51.

[0027] In some embodiments, the unlocking mechanism further includes an unlocking ball 54, and the unlocking sleeve 53 is fixed in the pressurized inner cylinder 51 by an unlocking pin 57, at which time the unlocking sleeve 53 is in the locked position. The unlocking sleeve 53 has an internal flow channel, and the top of the unlocking sleeve 53 has a conical ball seat 531 adapted to the unlocking ball 54. The outer wall of the unlocking sleeve 53 has a first water passage hole 510, which penetrates the internal flow channel of the unlocking sleeve 53 and is located below the conical ball seat 531. The unlocking ball 54 is configured to block the top opening of the internal flow channel of the unlocking sleeve 53 when placed in the conical ball seat 531.

[0028] In some embodiments, the outer wall of the pressurized inner cylinder 51 has a first limiting step 511, and the outer wall of the pressurized outer cylinder 52 has a second limiting step 522 adapted to the first limiting step 511, which is located above the first limiting step 511. When the first limiting step 511 and the second limiting step 522 abut against each other, the pressurized outer cylinder 52 cannot move downward relative to the pressurized inner cylinder 51.

[0029] In some embodiments, the pressure-holding core-taking pressure mechanism further includes a spring 59, under the action of the spring 59, the pressure outer cylinder 52 tends to move downward from the first position to the second position relative to the pressure outer cylinder 52.

[0030] In some embodiments, the pressurized inner cylinder 51 is connected to a differential mechanism, which includes a differential inner tube 41, a differential outer tube 42, a differential ball seat 43, and a differential ball 44. The outer tube of the differential outer tube 42 is sleeved outside the differential inner tube 41, and there is a seal 45 between the two. The lower end of the differential inner tube 41 is connected to the differential ball seat 43. The differential ball seat 43 has a flow channel hole and a sealing surface adapted to the differential ball 44. There is also a seal 45 between the differential ball seat 43 and the differential outer tube 42.

[0031] The differential outer tube 42 has a first pressure relief hole 46, which is located above the differential ball seat 43. When the differential ball 44 is inserted, the drilling fluid cannot flow downward from the differential ball seat 43, so it can only flow out from the first pressure relief hole 46 and become pressurized in the sealed cavity formed between the differential outer tube 42 and the differential inner tube 41.

[0032] The lower end of the differential outer tube 42 is connected to the pressurized inner cylinder 51. The corresponding position on the side wall of the differential outer tube 42 has a second water passage 48 that is adapted to the first water passage 510. When the unlocking sleeve 53 is in the locked position, the medium can flow from the internal flow channel of the pressurized inner cylinder 51 through the first water passage 510 and the second water passage 48 to the outside of the differential outer tube 42.

[0033] In some embodiments, one of the differential inner tube 41 and the differential outer tube 42 has a serrated retaining ring 411, and the other has a safety claw 421 adapted to the serrated retaining ring 411. When the differential outer tube 42 moves upward to a certain height relative to the differential inner tube 41, the safety claw 421 can be engaged with the serrated retaining spring 411. At this time, the differential outer tube 42 cannot move downward relative to the differential inner tube 41.

[0034] In some embodiments, the pressure-holding and coring mechanism further includes a pressure relief sleeve 55, which is fixed in the differential outer tube 42 by a safety pin 58. The upper end of the unlocking sleeve 53 is installed in the pressure relief sleeve 55, and the lower end of the unlocking sleeve 53 is installed in the pressure-pressurizing inner tube 51. The pressure relief sleeve 55 is located between the unlocking sleeve 53 and the differential outer tube 42. The differential outer tube 42 has a second pressure relief hole 47 at the position corresponding to the pressure relief sleeve 55. When the pressure relief sleeve 55 is fixed to the differential outer tube 42 with the safety pin 58, the second pressure relief hole 47 is blocked by the pressure relief sleeve 55. The pressure relief sleeve 55 and the two sealing rings installed at intervals on the pressure relief sleeve 55 block the second pressure relief hole 47, and the medium cannot flow to the outside of the differential outer tube 42 through the second pressure relief hole 47. When the pressure relief sleeve 55 and the safety pin 58 of the differential outer tube 42 are hydraulically sheared, the pressure relief sleeve 55 can move down relative to the differential outer tube 42. When the pressure relief sleeve 55 moves down to the predetermined position, the second pressure relief hole 47 on the differential outer tube 42 is exposed, and the medium can flow to the outside of the differential outer tube 42 through the second pressure relief hole 47.

[0035] Optionally, the differential outer tube 42 has a limiting step that is adapted to the pressure relief sleeve 55. When the pressure relief sleeve 55 descends to the point where it abuts against the limiting step, the pressure relief sleeve 55 descends to the predetermined position and cannot continue to move downward relative to the differential outer tube 42.

[0036] This application utilizes the sliding of the unlocking sleeve for unlocking, which is safer than pure pin fixing; the pressurization mechanism of this application can realize bidirectional movement of pressing down the core claw to cut the core and pressing up the core extraction chamber to maintain pressure.

[0037] like Figure 3 As shown, the coring device disclosed in this embodiment includes a pressure-holding coring pressurization mechanism, an outer tube assembly 1, and a coring chamber assembly 7. The pressure-holding coring pressurization mechanism and the differential outer tube 42 are both located inside the outer tube assembly 1. The uppermost end of the outer tube assembly 1 is connected to the oil drill pipe, and the lowermost end is connected to the coring drill bit 10. The inner wall of the coring drill bit 10 has a drill bit conical surface. A suspension ring 21 is provided inside the outer tube assembly 1. The lower end of the suspension ring 21 is threadedly connected to the first-stage separation mechanism 22, which is used to position the axial distance of the coring device in the outer tube.

[0038] The differential inner tube 41 is threadedly connected below the first-stage separation mechanism 22. The lower end of the pressurized outer cylinder 52 is threadedly connected to the sensor sleeve 6. An axial spring 59 is located between the pressurized inner cylinder 51 or the unlocking sleeve 53 and the sensor sleeve 6. In an exemplary embodiment, the spring 59 is sleeved on the unlocking sleeve 53, and the two ends of the spring 59 act on the outer step of the unlocking sleeve 53 and the upper end face of the sensor sleeve 6.

[0039] The sensor sleeve 6 contains encapsulated sensors, including pressure sensors, temperature sensors, etc.

[0040] The core chamber assembly 7 includes an insulated and pressure-maintaining core chamber and an inner tube 70. The lower end of the sensor sleeve 6 is connected to the insulated and pressure-maintaining core chamber, and the lower end of the insulated and pressure-maintaining core chamber is connected to the core tube 8. A pressure-maintaining controller 9 is installed at the lower part of the inner tube 70, and a pressurized core claw 81 is connected to the lower end of the core tube 8. The pressure-maintaining controller 9 includes a valve seat and a valve cover, with one end of the valve cover movably connected to the valve seat, allowing the core tube 8 to pass through the valve seat. The structure and working principle of the pressure-maintaining controller 9 are conventional technologies in this field and will not be described in detail here.

[0041] In this embodiment, the working principle of the core extraction device is as follows: During coring operations, the pressure holding controller 9 is activated, and the core tube 8 is located inside the valve seat 91. First, the PIPPC is lowered to the target formation, and coring drilling begins. At this time, the first water passage 510 of the unlocking sleeve 53 connects to the second water passage 48 of the differential outer tube 42. Drilling fluid flows out through the first water passage 510 and the second water passage 48 into the annulus of the outer tube assembly 1. Figure 1 As shown; After the predetermined core length is reached, the unlocking ball 54 is lowered and falls onto the conical ball seat 531 of the unlocking sleeve 53, forming hydraulic pressure to shear the unlocking pin 57 between the unlocking sleeve 53 and the pressurized inner cylinder 51. The unlocking sleeve 53 descends, and when the annular outer groove 532 on the unlocking sleeve 53 aligns with the steel ball 56 of the pressurized inner cylinder 51, the axial constraint of the pressurized outer cylinder 52 is unlocked. The spring 59 at the bottom of the unlocking sleeve 53 presses down on the sensor sleeve 6, pushing the core chamber assembly 7 downwards. Under the pressure at the upper end, the pressurized core claw 81 retracts inward along the drill bit conical surface 101. When the second limiting step 522 of the pressurized outer cylinder 52 abuts against the first limiting step 511 on the outer wall of the pressurized inner cylinder 51, the pressurized outer cylinder 52 moves into position, and the pressurized core claw 81 completes the cutting and encapsulation of the core. Figure 2 As shown.

[0042] Hydraulic pressure shears off the safety pin 58 between the pressure relief sleeve 55 and the differential outer tube 42. The pressure relief sleeve 55 descends, exposing the second pressure relief hole 47 on the differential outer tube 42, and the drilling fluid water passage reopens. At this time, the differential ball 44 is inserted and falls onto the differential ball seat 43. The resulting hydraulic pressure lifts the differential outer tube 42 and drives the pressurized inner tube 51 upward. The pressurized inner tube 51 pulls the pressurized outer tube 52 and the core chamber assembly 7 upward through the limiting step surface formed between it and the pressurized outer tube 52. After passing the pressure holding controller 9, the pressure holding controller 9 automatically closes.

[0043] When the upper edge of the second pressure relief hole 47 of the differential outer tube 42 passes the seal 45 between the differential outer tube 42 and the differential ball seat 43, the hydraulic pressure rapidly and continuously decreases until the upper end of the core tube 8 presses against the inner tube 70, completing the lifting and shutting off the mud pump. At this time, the safety claw 421 on the differential outer tube 42 is suspended on the serrated retaining spring 411 of the differential inner cylinder 41. The heat-insulating and pressure-maintaining core chamber can be lifted by lifting the differential inner cylinder 41.

[0044] The coring device in this embodiment can achieve low-disturbance coring with dual-cylinder single-action. After coring is completed, the coring cylinder and core claw can move in both directions. First, it moves downward to perform a pressure-type core cutting action to wrap the core and prevent loose core from falling out. Then, it moves upward to trigger the pressure holding controller to complete the pressure holding action.

[0045] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A pressure-holding coring mechanism, characterized in that, include: Pressurized inner cylinder (51); The upper end of the pressure outer cylinder (52) is fitted over the pressure inner cylinder (51); Steel balls (56) are used for axial locking of the outer pressurized cylinder (52) and the inner pressurized cylinder (51). The steel balls (56) can be installed simultaneously in the cylinder walls of both the inner pressurized cylinder (51) and the outer pressurized cylinder (52) to achieve the axial locking. An unlocking mechanism for releasing the axial lock between the pressurized outer cylinder (52) and the pressurized inner cylinder (51) includes an unlocking sleeve (53) installed inside the pressurized inner cylinder (51). The unlocking sleeve (53) has a locking position and an unlocking position. By sliding the unlocking sleeve (53) downward relative to the pressurized inner cylinder (51), the unlocking sleeve (53) is switched from the locking position to the unlocking position. When the unlocking sleeve (53) is in the unlocking position, the steel ball (56) exits from the cylinder wall of the pressurized outer cylinder (52) and is simultaneously installed in the cylinder walls of the unlocking sleeve (53) and the pressurized inner cylinder (51), thereby releasing the axial lock. When the axial lock is released, the pressurized outer cylinder (52) can move downward relative to the pressurized inner cylinder (51) from a first position to a second position. A steel ball (56) is installed in a hole on the wall of the pressurized inner cylinder (51). The diameter of the steel ball (56) is larger than the wall thickness of the pressurized inner cylinder (51). The inner wall of the pressurized outer cylinder (52) has an annular groove (521) that matches the steel ball (56). When the pressurized outer cylinder (52) is in the first position, part of the steel ball (56) is installed in the pressurized inner cylinder (51), and the other part of the steel ball (56) is installed in the annular groove (521) on the inner wall of the pressurized outer cylinder (52). The pressurized inner cylinder (51) is axially fixed to the pressurized outer cylinder (52) and can rotate circumferentially through the steel ball (56). The outer wall of the unlocking sleeve (53) has an annular outer groove (532) that is adapted to the steel ball (56) on the pressurized inner cylinder (51). When the unlocking sleeve (53) is in the unlocked position, the annular outer groove (532) on the unlocking sleeve (53) is aligned with the steel ball (56) on the pressurized inner cylinder (51). The steel ball (56) can exit from the annular inner groove (521) of the pressurized outer cylinder (52) and enter the annular outer groove (532) of the unlocking sleeve (53), thereby releasing the axial lock.

2. The pressure-holding coring mechanism according to claim 1, characterized in that, The unlocking mechanism also includes an unlocking ball (54), and the unlocking sleeve (53) is fixed in the pressurized inner cylinder (51) by an unlocking pin (57). At this time, the unlocking sleeve (53) is in the locked position. The unlocking sleeve (53) has an internal flow channel. The top of the unlocking sleeve (53) has a conical ball seat (531) that is adapted to the unlocking ball (54). The outer wall of the unlocking sleeve (53) has a first water passage hole (510). The first water passage hole (510) passes through the flow channel inside the unlocking sleeve (53). The first water passage hole (510) is below the conical ball seat (531). The unlocking ball (54) is configured to block the top opening of the internal flow channel of the unlocking sleeve (53) when it is placed in the conical ball seat (531).

3. The pressure-holding coring mechanism according to claim 1, characterized in that, The outer wall of the pressurized inner cylinder (51) has a first limiting step (511), and the outer wall of the pressurized outer cylinder (52) has a second limiting step (522) that is adapted to the first limiting step (511). When the first limiting step (511) and the second limiting step (522) abut against each other, the pressurized outer cylinder (52) cannot move downward relative to the pressurized inner cylinder (51).

4. The pressure-holding coring mechanism according to claim 1, characterized in that, It also includes a spring (59), under the action of the spring (59), the pressurized outer cylinder (52) tends to move downward from the first position to the second position relative to the pressurized outer cylinder (52).

5. The pressure-holding coring mechanism according to claim 1, characterized in that, It also includes a differential mechanism, which includes a differential inner tube (41), a differential outer tube (42), a differential ball seat (43), and a differential ball (44). The lower end of the differential inner tube (41) is connected to the differential ball seat (43), and the differential ball seat (43) has a flow channel hole and a sealing surface that are adapted to the differential ball (44). The lower end of the differential outer tube (42) is connected to the pressurized inner cylinder (51). The corresponding position on the side wall of the differential outer tube (42) has a second water passage (48) that is compatible with the first water passage (510). When the unlocking sleeve (53) is in the locked position, the medium can flow from the internal flow channel of the pressurized inner cylinder (51) through the first water passage (510) and the second water passage (48) to the outside of the differential outer tube (42).

6. The pressure-holding coring mechanism according to claim 5, characterized in that, The differential outer tube (42) has a first pressure relief hole (46), which is located above the differential ball seat (43); In the differential inner tube (41) and differential outer tube (42), one has a serrated retaining ring (411), and the other has a safety claw (421) that is adapted to the serrated retaining ring (411). When the differential outer tube (42) moves upward to a certain height relative to the differential inner tube (41), the safety pawl (421) can be engaged with the serrated spring clip (411). At this time, the differential outer tube (42) cannot move downward relative to the differential inner tube (41).

7. A pressure-holding coring mechanism according to claim 5, characterized in that, It also includes a pressure relief sleeve (55), which is fixed in the differential outer tube (42) with a safety pin (58). The upper end of the unlocking sleeve (53) is installed in the pressure relief sleeve (55), and the lower end of the unlocking sleeve (53) is installed in the pressurized inner tube (51). The pressure relief sleeve (55) is located between the unlocking sleeve (53) and the differential outer tube (42). The differential outer tube (42) has a second pressure relief hole (47) at the position corresponding to the pressure relief sleeve (55). When the pressure relief sleeve (55) is fixed to the differential outer tube (42) with a safety pin (58), the second pressure relief hole (47) is blocked by the pressure relief sleeve (55), and the medium cannot flow to the outside of the differential outer tube (42) through the second pressure relief hole (47). When the pressure relief sleeve (55) and the safety pin (58) of the differential outer tube (42) are hydraulically sheared, the pressure relief sleeve (55) can move down relative to the differential outer tube (42). When the pressure relief sleeve (55) moves down to the predetermined position, the second pressure relief hole (47) on the differential outer tube (42) is exposed, and the medium can flow to the outside of the differential outer tube (42) through the second pressure relief hole (47).

8. A pressure-holding coring mechanism according to claim 7, characterized in that, The differential outer tube (42) has a limiting step that is adapted to the pressure relief sleeve (55). When the pressure relief sleeve (55) descends to the point where it abuts against the limiting step of the pressure relief sleeve (55), the pressure relief sleeve (55) descends to the predetermined position and the pressure relief sleeve (55) cannot continue to move downward relative to the differential outer tube (42).

Images