CN111894478B

CN111894478B - RD type safety joint

Info

Publication number: CN111894478B
Application number: CN202010658031.1A
Authority: CN
Inventors: 罗伟波; 赵亮; 景建平; 张锦锦; 万文超
Original assignee: Baoji Changyou Petroleum Equipment Co ltd
Current assignee: Baoji Changyou Petroleum Equipment Co ltd
Priority date: 2020-07-09
Filing date: 2020-07-09
Publication date: 2022-03-29
Anticipated expiration: 2040-07-09
Also published as: CN111894478A

Abstract

The invention discloses an RD-type safety joint which comprises an upper mandrel, wherein the top end and the bottom end of the upper mandrel are sequentially connected with an upper joint and a lower mandrel, and a hydraulic locking device for locking the upper mandrel and the lower mandrel and an unlocking mechanism for unlocking are arranged in the safety joint. The safety joint disclosed by the invention is suitable for various complex well conditions, and is particularly suitable for well conditions with serious sand production. When in normal operation, the device is connected with other downhole tools such as a packer and the like for use, can normally transmit tension, pressure, torque and the like, can bear the actions of tubular column internal pressure and annular external pressure in a shaft, and cannot influence the operation of other tools; the safety joint is simple and rapid to release, convenient and reliable to operate, after tools on the lower portion of the safety joint are clamped or buried, tool strings on the upper portion of the safety joint can be smoothly released and lifted out of a wellhead, the tools can still be normally used in subsequent testing work, convenience is brought to subsequent operations of salvaging, milling and the like, and accordingly economic loss is greatly reduced.

Description

RD type safety joint

Technical Field

The invention relates to the technical field of safety connectors, in particular to an RD type safety connector.

Background

An oil well is a borehole drilled by a drilling method. After drilling oil layer, the oil layer casing is set, and the cement is injected into the annular space between casing and well wall to maintain well wall and seal oil, gas and water layer. Before production, various parameters such as temperature, pressure, depth and the like of an oil layer in a well need to be tested so as to obtain more test parameters, and the smooth production of crude oil of the oil layer is facilitated.

At present, due to the development of the technology, the drilling and exploitation depths are deepened, so that measuring tools are increased, the tool string is generally integrally called, the integral lowering depth of the tool string is deeper, the geological condition in a well is more complex, the problem which easily occurs is that a pipe column of sand or other reasons in the well is clamped, the tool string is lifted, each part of the tool string is damaged due to the fact that the tool string is lifted by a large lifting force, the reuse quality is influenced, and the tool string has large potential safety hazards. If not, it causes more economic loss.

Disclosure of Invention

Aiming at the existing problems, the invention aims to provide an RD type safety joint which comprises an upper mandrel, wherein the top end and the bottom end of the upper mandrel are sequentially connected with an upper joint and a lower mandrel, an outer oil chamber cylinder, an outer rupture disc cylinder and an outer lock claw cylinder are movably sleeved and fixedly connected with the outer circle of the upper mandrel along the direction of the upper joint towards the lower mandrel, the bottom end of the outer lock claw cylinder is movably connected with a connecting outer cylinder which can be separated from the outer lock claw cylinder, the bottom end of the connecting outer cylinder is fixedly connected with a lower joint, the bottom of the lower joint is connected with other underground tools, and the safety joint is vertically connected with a plurality of tools to form an integral tool string. When the downhole tool connected with the lower joint is stuck in a downhole accident, the lower joint and the downhole tool connected with the lower joint are integrally separated from the safety joint by the operation mode of separating the connecting outer cylinder from the locking claw outer cylinder, tools above the safety joint are lifted and recovered, the loss of the downhole tool is reduced, and the safety joint is simple and reliable in releasing and lifting mode and has high popularization value.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: the utility model provides a RD type safety joint, includes the upper mandrel, the upper mandrel is the inside straight-bar structure that has through the passageway the upper mandrel top and bottom have connected gradually upper joint and lower dabber, its characterized in that: the outer circle of the upper mandrel is movably sleeved along an upper joint towards the direction of the lower mandrel and fixedly connected with an oil chamber outer cylinder, a rupture disc outer cylinder and a locking claw outer cylinder in sequence, the bottom end of the locking claw outer cylinder is movably connected with a connecting outer cylinder which can be separated from the locking claw outer cylinder, the bottom end of the connecting outer cylinder is fixedly connected with a lower joint, a hydraulic locking device used for locking the upper mandrel relative to the oil chamber outer cylinder is arranged between the outer circle of the upper mandrel and the oil chamber outer cylinder, an unlocking mechanism which acts on the hydraulic locking device and enables the upper mandrel to move relative to the oil chamber outer cylinder is arranged on the rupture disc outer cylinder, a pressure sleeve used for connecting the outer cylinder and the locking claw outer cylinder to be separated from a release is arranged in the lower joint, and the pressure sleeve has rated fracture pressure; an oil filling port is formed in the outer cylinder of the oil chamber corresponding to the cavity, and a lower oil filling plug and an O-shaped ring for opening and closing the oil filling port in a sealing manner are arranged in the oil filling port.

Preferably, the hydraulic locking device comprises a cavity formed by the excircle of the upper mandrel and the inner hole of the oil chamber outer barrel, one end of the cavity, which is close to the upper joint, is sealed, the other end of the cavity is provided with a first channel communicated with the unlocking mechanism, one end of the cavity, which is close to the first channel, is internally provided with a power valve assembly, the power valve assembly is matched with the unlocking mechanism, the cavity and the first channel are opened and closed, and the power valve assembly and the cavity part, which is close to one end of the upper joint, of the cavity are filled with liquid locking media in the state that the lower joint is not released from the lower mandrel.

Preferably, the unlocking mechanism comprises a second channel reserved between the outer circle of the upper mandrel and the inner hole of the outer barrel of the rupture disk, the second channel is communicated with the first channel, the outer barrel wall of the rupture disk is provided with the rupture disk communicated with the second channel, and one end, far away from the first channel, of the second channel is sealed through the top end of the lower mandrel.

Preferably, the bottom end of the outer cylinder of the locking claw is provided with a releasing mechanism, the whole locking claw is of an elastic claw structure, the releasing mechanism specifically comprises claw rods which are arranged at the bottom end of the outer cylinder of the locking claw at intervals along the circumferential direction and are provided with hammer-head-shaped structures, a first V-shaped groove for limiting the outer cylinder is formed in the excircle of each claw rod, a first V-shaped protrusion matched with the first V-shaped groove for limiting is arranged on the outer cylinder of the connecting claw rod, a second V-shaped groove which is of a certain width and used for retracting the claw rod and releasing limiting of the outer cylinder is formed in the excircle of the lower mandrel, and the second V-shaped groove is located on one side, close to the upper joint, of the claw rod in the state that the lower mandrel is not released.

Preferably, the pressing sleeve is integrally provided with an open tubular structure on one side, a boss extends outwards from the end part on one side of the opening of the tubular structure, the bottom end of the lower mandrel is pressed against the inner bottom surface of the tubular structure, and a first shoulder supported by the boss and a sliding channel used after the tubular structure and the boss are broken are arranged in the lower joint.

Preferably, the top of the oil chamber outer cylinder is connected with a limiting block used for limiting the upper mandrel in a one-way mode towards the upper joint direction, and a first protrusion matched with the limiting block is arranged on the upper mandrel.

Preferably, the power valve assembly comprises a shell, and a first perforation, a second perforation and a third perforation which are communicated with each other in the shell, a pressure spring and a sealing head are sequentially arranged in the second perforation, the pressure spring is connected with the sealing head, one end of the sealing head movably penetrates through the third perforation, one end of the sealing head extends into the first channel under the action of the pressure spring, and a second shoulder used for limiting the whole power valve assembly is arranged in the oil chamber outer cylinder.

Preferably, a locking ring is movably arranged in the first channel, a third channel is arranged between an inner hole of the locking ring and the outer circle of the upper mandrel, the end part of the locking ring is abutted against the end part of the sealing head in the hydraulic locking state of the upper mandrel and can push the sealing head to separate from the sealing effect on the third through hole, and a one-way back-buckling threaded matching structure in the same direction as the limiting block is arranged between the outer circle of the locking ring and the inner hole of the oil chamber outer barrel.

Preferably, a balance piston is movably arranged in the second channel, one end of the balance piston abuts against one end, away from the sealing head, of the locking ring after moving, and a third shoulder for unidirectionally limiting the direction of the balance piston towards the lower joint is arranged on an inner hole of the outer cylinder of the rupture disc on one side, close to the outer cylinder of the oil chamber, of the rupture disc.

Preferably, a locking block is embedded at the bottom of the outer barrel of the rupture disc, a locking groove which is matched with the locking block and used for locking the released lower mandrel with the outer barrel of the rupture disc is formed in the lower mandrel, and a spring which is used for pushing the locking block into the locking groove is embedded at one side, close to the outer barrel of the locking claw, of the locking block.

The invention has the beneficial effects that: (1) the safety joint disclosed by the invention can be suitable for various complex well conditions, and is particularly suitable for well conditions with serious sand production. When in normal operation, the downhole tool is connected with other downhole tools such as a packer and the like for use, so that tension, pressure, torque and the like can be normally transmitted, and the operation of other tools cannot be influenced. (2) The safety joint is simple and quick to release, convenient and reliable to operate, so that after tools at the lower part of the safety joint are buried, the tools at the upper part of the safety joint can be smoothly lifted without being damaged under the condition of not being subjected to burying resistance, the tools at the part can still be normally used in subsequent testing work, and economic loss is reduced. (3) When the tool string is not buried and is normally placed, the hydraulic locking device in the tool string and the structural design of each part ensure that the whole structure of the safety joint is reliable, the tool string has high tensile strength and accurate length and size, and the accuracy of measuring data by matching with other measuring tools is facilitated.

Drawings

Fig. 1 is a structural view of the safety joint of the present invention.

Fig. 2 is a schematic vertical cross-section of fig. 1 in accordance with the present invention.

FIG. 3 is a lateral enlarged view of FIG. 2A of the present invention.

FIG. 4 is a lateral enlarged view of the invention at FIG. 2B.

FIG. 5 is a lateral enlarged view of the invention at FIG. 2C.

FIG. 6 is a lateral enlarged view of the invention at FIG. 2D.

FIG. 7 is a laterally enlarged view of the invention at FIG. 2E.

Fig. 8 is a lateral enlarged view of the invention at fig. 2F.

FIG. 9 is an enlarged view of the power valve assembly structure of the present invention.

FIG. 10 is an enlarged view of the fitting structure of the lower core shaft and the press sleeve of the present invention.

FIG. 11 is an enlarged view of FIG. 8I of the present invention.

Fig. 12 is a perspective view of the outer cylinder of the locking pawl of the present invention.

Wherein: reference numerals 18-23 are all support seals, 24-29 and 31-33 are all O-shaped sealing rings, and the support seals and the O-shaped sealing rings are matched as shown in 36 and 37 in FIG. 9; 30 is a rectangular sealing ring.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following further describes the technical solution of the present invention with reference to the drawings and the embodiments.

Referring to fig. 1 to 12, an RD type safety joint (RD is a short term of a rupture disc, that is, a rupture disc) includes an upper mandrel 2, the upper mandrel 2 is a straight rod structure having a through channel 201 inside, an upper joint 1 and a lower mandrel 9 are sequentially connected to the top end and the bottom end of the upper mandrel 2, an oil chamber outer cylinder 4, a rupture disc outer cylinder 7 and a locking claw outer cylinder 10 are movably sleeved on the outer circle of the upper mandrel 2 along the upper joint 1 toward the lower mandrel 9 and fixedly connected in sequence, the connection modes of the above components are preferably threaded connections, a connection outer cylinder 13 capable of being detached from the bottom end of the locking claw outer cylinder 10 is movably connected to the bottom end of the connection outer cylinder 13, a lower joint 14 is fixedly connected to the bottom end of the connection outer cylinder 13, and the bottom of the lower joint 14 is connected to other downhole tools. When the downhole tool connected with the lower joint 14 is subjected to excessive sand in the well and buried and can not be lowered continuously, the lower joint 14 and the downhole tool connected with the lower joint are integrally separated from the safety joint by an operation mode of separating the connecting outer cylinder 13 from the locking claw outer cylinder 10, tools above the safety joint are lifted and recovered, and the loss of the downhole tool is reduced.

In order to enable the safety joint to have simple, quick and reliable practical effects, a hydraulic locking device used for locking the upper mandrel 2 relative to the oil chamber outer cylinder 4 is arranged between the outer circle of the upper mandrel 2 and the oil chamber outer cylinder 4, an unlocking mechanism which acts on the hydraulic locking device and enables the upper mandrel 2 to move relative to the oil chamber outer cylinder 4 is arranged on the rupture disc outer cylinder 7, a pressing sleeve 15 which is used for connecting the outer cylinder 13 and the locking claw outer cylinder 10 to be separated from a releasing hand is arranged in the lower joint 14, and the pressing sleeve 15 has rated fracture pressure. The working principle is as follows: when the underground tool is not buried, the underground tool connected with the upper end and the lower end of the upper joint 1 and the lower joint 14 of the safety joint and the safety joint are integrally and smoothly arranged below the safety joint, the hydraulic locking device locks the positions of the upper mandrel 2 and the lower mandrel 9 relative to the oil chamber outer cylinder 4, the rupture disc outer cylinder 7 and the locking claw outer cylinder 10, and the connecting outer cylinder 13 and the lower joint 14 are connected under the action of gravity of the underground tool connected with the lower joint 14Is tightly pulled at the bottom of the outer cylinder 10 of the locking claw Terminal endSo that the safety joint has a fastened integral structure in the process of the lower part, and the stability of tools connected with the two ends of the safety joint in the lowering process is ensuredAnd accuracy, which is convenient for accurately reaching the predicted relative depth and improves the quality of the underground measurement operation. When the underground sand is discharged to bury the tools connected with the lower joint 14, the tools are prevented from being lowered integrally, the hydraulic locking device is released through the unlocking mechanism to release the positions of the upper mandrel 2 and the lower mandrel 9 relative to the oil chamber outer cylinder 4, the rupture disc outer cylinder 7 and the locking claw outer cylinder 10, so that the upper mandrel 2 and the lower mandrel 9 move relative to the oil chamber outer cylinder 4, the rupture disc outer cylinder 7 and the locking claw outer cylinder 10 towards the direction of the pressing sleeve 15, the lower mandrel 9 acts on the pressing sleeve 15 to break the pressing sleeve 15, the connecting outer cylinder 13 is separated from the locking claw outer cylinder 10, the lower joint 14 and the underground tools connected with the lower joint are separated from the safety joint integrally, the releasing operation of the safety joint is completed, and then the safety joint and the tools above the safety joint are lifted up through the upper joint 1. The releasing and lifting mode is simple and reliable, and has high popularization value.

Specifically, the hydraulic locking device comprises a cavity 204 formed by an outer circle of the upper mandrel 2 and an inner hole of the oil chamber outer cylinder 4, one end of the cavity 204, which is close to the upper joint 1, is sealed, the other end of the cavity is provided with a first channel 101 communicated with the unlocking mechanism, a power valve assembly 5 is arranged in one end of the cavity 204, which is close to the first channel 101, the power valve assembly 5 is matched with the unlocking mechanism to open and close the cavity 204 and the first channel 101, and under the condition that the lower joint 14 is not released from the lower mandrel 9, the part of the cavity 204, which is close to one end of the upper joint 1, of the power valve assembly 5 and the cavity 204 is filled with a liquid locking medium (preferably hydraulic oil) to play a hydraulic locking role. Preferably, an oil filling port 205 is formed in the oil chamber outer cylinder 4 corresponding to the cavity 204, and a lower oil filling plug 17 and an O-ring 26 are arranged in the oil filling port 205 for opening and closing the oil filling port 205. The locking mode is as follows: the cavity 204 is filled with hydraulic oil, the upper end of the cavity is sealed by the contact of the excircle of the upper mandrel 2 and the inner hole of the oil chamber outer cylinder 4, and the lower end of the cavity is sealed by the power valve assembly 5, so that the upper mandrel 2 and the lower mandrel 9 are relatively locked relative to the oil chamber outer cylinder 4, the rupture disc outer cylinder 7 and the locking claw outer cylinder 10. When the tool is buried, the unlocking mode is as follows: the unlocking mechanism acts on the power valve assembly 5 and opens the power valve assembly, the cavity 204 is communicated with the first channel 101, hydraulic oil in the cavity 204 is decompressed, the locking effect on the upper mandrel 2 and the lower mandrel 9 is released, the upper mandrel 2 and the lower mandrel 9 continue to move downwards relative to the oil chamber outer cylinder 4, the rupture disc outer cylinder 7 and the locking claw outer cylinder 10 under the action of the unlocking mechanism, the pressing sleeve 15 is broken, the connecting outer cylinder 13 is separated from the locking claw outer cylinder 10, the lower joint 14 and a downhole tool connected with the lower joint are separated from the safety joint integrally, and the releasing operation of the safety joint is completed.

Specifically, the unlocking mechanism comprises a second channel 102 reserved between the outer circle of the upper mandrel 2 and the inner hole of the outer rupture disc cylinder 7, the second channel 102 is communicated with the first channel 101, a rupture disc 16 communicated with the second channel 102 is arranged on the wall of the outer rupture disc cylinder 7, and one end, far away from the first channel 101, of the second channel 102 is sealed at the top end of the lower mandrel 9. The specific unlocking mode is as follows: after the tool is buried, liquid is squeezed between the tool and an inner hole of a pipe column, so that the rupture disc 16 is ruptured after reaching a rated value, the liquid circulates into the first channel 101 through the second channel 102, then acts on the power valve assembly 5 and opens the power valve assembly, the cavity 204 is communicated with the first channel 101, hydraulic oil in the cavity 204 is decompressed, the locking effect on the upper mandrel 2 and the lower mandrel 9 is relieved, the pressing is continued, the upper mandrel 2 and the lower mandrel 9 move downwards, the pressing sleeve 15 is broken, the connecting outer cylinder 13 is separated from the locking claw outer cylinder 10, and the releasing operation of the safety joint is completed.

Further, in order to ensure the reliability of the connection between the outer cylinder 13 and the outer cylinder 10 of the locking claw and the simplicity and rapidness of releasing the lock claw, the bottom end of the outer cylinder 10 of the locking claw is provided with a releasing mechanism, the whole body of the claw lock is of an elastic claw structure, and specifically comprises claw rods 35 which are arranged at the bottom end of the outer locking claw cylinder 10 at intervals along the circumferential direction and have hammer-head-shaped structures, first V-shaped grooves 35a for limiting the connecting outer cylinder 13 are arranged on the excircle of each claw rod 35, the connecting outer cylinder 13 is provided with a first V-shaped bulge 13a matched with the first V-shaped groove 35a for limiting, a second V-shaped groove 9a which has a certain width and is used for retracting the claw rod 35 and releasing the limit with the connecting outer cylinder 13 is arranged on the excircle of the lower mandrel 9, in a state where the lower joint 14 is not released from the lower mandrel 9, the second V-shaped groove 9a is located on the side of the claw rod 35 close to the upper joint 1. The specific working mode is as follows: when the locking claw is not released, the first V-shaped protrusion 13a is matched and pressed in the first V-shaped groove 35a, and meanwhile, each claw rod 35 is pressed on the excircle of the lower mandrel 9 at the lower end of the second V-shaped groove 9a under the action of the elasticity of the claw rod 35, so that a tool for connecting the outer cylinder 13 with the lower joint 14 and the lower end of the lower joint is tensioned at the bottom end of the outer cylinder 10 of the locking claw, and the whole body is released at the same time. Preferably, a wiping ring 34 which is attached to the outer circle of the lower mandrel 9 is nested in the inner hole at the bottom of the connecting outer cylinder 13, a slope shoulder 34a is arranged on one side of the wiping ring 34 close to the end of the lower mandrel 9, and the slope shoulder 34a has the function of bringing impurities such as slurry into the second V-shaped groove 9a when the end of the lower mandrel 9 retracts after the pressing sleeve 15 is broken, so as to prevent the retraction of the claw rod 35 and cause the problem of failed releasing. The inclined shoulder 34a can effectively scrape off impurities such as slurry on the end part of the lower core shaft 9, and the second V-shaped groove 9a is ensured to be in a clearance state. When the hand is thrown, the unlocked upper mandrel 2 and the unlocked lower mandrel 9 move downwards to cause the pressing sleeve 15 to break, the pressure pressed into the second channel 102 through the rupture disc 16 flows downwards to push the top end of the lower mandrel 9 and drive the upper mandrel 2 to continue to move downwards, after the second V-shaped grooves 9a move to the position horizontally aligned with the claw rods 35, each claw rod 35 retracts into the second V-shaped groove 9a by means of the inward elasticity of the claw rod 35, the first V-shaped grooves 35a release the limit of the first V-shaped protrusions 13a, namely the connection and fixation of the locking claw outer cylinder 10 and the connection outer cylinder 13 is released, then the upper joint 1 and the outer cylinder 4 are lifted upwards, so that the locking claw outer cylinder 10 is separated from the connection outer cylinder 13, the lower joint 14 and tools connected with the locking claw outer cylinder 10, and the hand throwing lifting operation is completed.

In order to facilitate smooth completion of releasing operation after the pressure sleeve 15 is broken, the pressure sleeve 15 is integrally a cylindrical structure 15a with an opening on one side, a boss 15b extends outwards from the end part of the cylindrical structure 15a on the opening side, the bottom end of the lower mandrel 9 is pressed against the inner bottom surface of the cylindrical structure 15a, and a first shoulder 14a for supporting the boss 15b and a sliding channel 14b for breaking the cylindrical structure 15a and the boss 15b are arranged in the lower joint 14. After the lower mandrel 9 acts downward on the inner bottom surface of the cylindrical structure 15a and the acting force reaches the tensile strength of the cylindrical structure 15a and the boss 15b, the boss 15b is broken at the joint of the cylindrical structure 15a and the cylindrical structure 15a under the support of the first shoulder 14a (broken at fig. 10H), the cylindrical structure 15a is continuously pushed into the sliding channel 14b, so that after the second V-shaped groove 9a moves to a position horizontally aligned with the claw rod 35, each claw rod 35 retracts into the second V-shaped groove 9a by virtue of the inward elasticity of the claw rod 35, so that the first V-shaped groove 35a releases the limit of the first V-shaped protrusion 13a, namely, the connection fixation of the claw outer cylinder 10 and the connection outer cylinder 13 is released, and then the joint 1 and the oil chamber outer cylinder 4 are lifted upwards, and the releasing and lifting operation is completed.

Further in order to facilitate the lifting operation of the safety joint, the top of the oil chamber outer cylinder 4 is connected with a limiting block 3 (preferably a locking nut) for unidirectionally limiting the direction of the upper mandrel 2 towards the upper joint 1, the locking nut is in threaded connection with an inner hole in the top of the oil chamber outer cylinder 4, and the upper mandrel 2 is provided with a first protrusion 2a matched with the limiting block 3. When the upper mandrel 2 is hydraulically locked by hydraulic oil in the cavity 204, the first protrusion 2a is matched with the locking nut to limit the movement of the upper mandrel 2 towards the direction of the upper joint 1; when the hydraulic locking of the upper mandrel 2 is released, the upper mandrel 2 moves downward relative to the lock nut, and the releasing operation is completed. The locking nut is used for limiting the upward direction of the upper mandrel 2 in a one-way mode, so that when the safety joint is lifted, only the locking nut needs to act on the upper joint 1, the external lifting force does not need to be applied to the oil chamber outer cylinder 4 unnecessarily, the complexity of the lifting operation in a deep well is simplified, and meanwhile the structure is lifted quickly and reliably.

Further, in order to facilitate smooth pressure relief of hydraulic oil in the cavity 204, the power valve assembly 5 includes a housing 51 and a first through hole 501, a second through hole 502 and a third through hole 503 which are mutually communicated in the housing 51, a pressure spring 5a and a sealing head 5b are sequentially arranged in the second through hole 502, the pressure spring 5a and the sealing head 5b are connected, one end of the sealing head 5b extends into the first channel 101 under the action of the pressure spring 5a, and a second shoulder 4a used for limiting the whole power valve assembly 5 is arranged in the oil chamber outer cylinder 4. When the pressure is released, the liquid entering the first channel 101 through the second channel 102 pushes the sealing head 5b to press the pressure spring 5a to move towards the second through hole 502 under the action of the pressure, so that the sealing effect on the third through hole 503 is eliminated, preferably, the aperture of the second through hole 502 is larger than the outer diameter of the sealing head 5b, after the sealing head 5b moves into the second through hole 502, the hydraulic oil in the cavity 204 flows through the third through hole 503 through the gap between the sealing head 5b and the second through hole 502, and finally the pressure is released, and meanwhile, the pressure spring 5a enables the sealing head 5b to retract without contacting the port of the first through hole 501 to block the port. After pressure relief, the liquid pressure in the second channel 102 pushes the lower mandrel 9 to drive the upper mandrel 2 to move downwards, and subsequent releasing and lifting operations are completed.

Further, in order to facilitate smooth pressure relief of hydraulic oil in the cavity 204, a lock ring 6 is movably arranged in the first channel 101, a third channel 103 is arranged between an inner hole of the lock ring 6 and the outer circle of the upper mandrel 2, and the end of the lock ring 6 abuts against the end of the sealing head 5b in the hydraulic locking state of the upper mandrel 2 and can push the sealing head 5b to separate from the sealing effect on the third through hole 503. Preferably, the sealing head 5b is specifically configured as a position-limiting portion 5b1 and a pressure-relief portion 5b2 with different outer diameters, the position-limiting portion 5b1 is located in the second through hole 502 and abuts against one end of the pressure spring 5a, the pressure-relief portion 5b2 is arranged in the third through hole 503 and leaves a pressure-relief gap 504 with the inner hole of the third through hole 503, the end portion of the pressure-relief portion extends into the first channel 101, the connecting transition portion between the position-limiting portion 5b1 and the pressure-relief portion 5b2 is configured as a cone-shaped structure 5b3 facing the direction of the third through hole 503 and sealing the port of the third through hole 503, and since the end portion of the pressure-relief portion 5b2 extends into the first channel 101 and abuts against the end portion of the locking ring 6, when the liquid in the second channel 102 acts on the locking ring 6, the locking ring 6 can push the pressure-relief portion 5b2 to move towards the second through hole 502 for the first time, so that the cone-shaped structure 5b3 transitioning with the position-limiting portion 5b1 instantaneously opens the pressure-relief port to seal the third through hole 503, so that the hydraulic oil in the cavity 204 can be quickly discharged to the first passage 101 through the third passage 103 for the first time, and the locking of the upper mandrel 2 and the lower mandrel 9 is released. A one-way reverse-buckling thread matching structure which is in the same direction as the limiting block 3 is arranged between the outer circle of the locking ring 6 and the inner hole of the oil chamber outer cylinder 4, namely, the locking ring 6 is always kept to be abutted against the end part of the pressure relief part 5b2, and the pressure can be quickly relieved at the first time when the hand is released.

Further, in order to enable the liquid pressure in the second channel 102 to smoothly drive the locking ring 6 to push the sealing head 5b, a balance piston 8 is movably arranged in the second channel 102, one end of the balance piston 8 abuts against one end, away from the sealing head 5b, of the locking ring 6 after moving, a third shoulder 7a for unidirectionally limiting the direction of the balance piston 8 towards the lower joint 14 is arranged on an inner hole of the rupture disc outer cylinder 7 on one side of the rupture disc 16 close to the oil chamber outer cylinder 4, and the function of the third shoulder is to prevent the balance piston 8 from having an obstruction function on the rupture disc 16 and the channel thereof to be communicated with the second channel 102. Because the balance piston 8 is arranged in the second channel 102, the preferable relative movement between the balance piston 8 and the inner hole of the second channel 102 has better sealing performance, and meanwhile, the reaction force caused by the pressurized liquid entering the second channel 102 through the rupture disk 16 and the hydraulic oil decompressed by the cavity 204 is prevented, so that the normal decompression problem of the upper mandrel 2 is influenced, the pressurized liquid is isolated from the hydraulic oil by the balance piston 8, so that the hydraulic oil can be normally decompressed, therefore, the balance piston 8 can be synchronously and efficiently pushed to be in contact with the locking ring 6 under the liquid pressure of the second channel 102, the sealing head 5b is pushed to complete the hydraulic operation of the cavity 204, and the accuracy and reliability of the decompression of the opening of the power valve assembly 5 are further improved by the balance piston 8.

Further, in order to improve the stability of the safety joint when the safety joint is lifted integrally, a locking block 11 is embedded at the bottom of the outer barrel 7 of the rupture disc, a locking groove 9b which is matched with the locking block 11 and locks the released lower mandrel 9 and the outer barrel 7 of the rupture disc is arranged on the lower mandrel 9, and a spring 12 which is used for pushing the locking block 11 into the locking groove 9b is embedded at one side, close to the outer barrel 10 of the locking claw. After the upper mandrel 2 is unlocked hydraulically, the upper mandrel 2 and the lower mandrel 9 move towards the pressing sleeve 15, preferably, a fourth shoulder 9c matched with the upper mandrel 2 to press downwards is arranged on the lower mandrel 9, meanwhile, the fourth shoulder 9c can bear the downward pressing effect of gravity from a tool on the upper portion of the upper mandrel 2 on the lower mandrel 9, so that after the pressing sleeve 15 is broken, the claw rod 35 is ensured to retract into the second V-shaped groove 9a, the connection fastening effect on the connecting outer cylinder 13 is relieved, the locking groove 9b corresponds to the locking block 11, the locking block 11 is pushed into the locking groove 9b under the action of the spring 12, the lower mandrel 9 and the locking claw outer cylinder 10 form a fixed whole, and the whole safety joint is lifted through the upper joint 1 together with the lifting effect of the first bulge 2a on the upper mandrel 2 on the locking nut and the outer cylinder 4.

Preferably, the inside of the outer cylinder 7 of the rupture disc and the bottom end of the outer cylinder 4 of the oil chamber are provided with a conical limiting structure (as shown in fig. 5G), and the structure is used for enhancing the pressing effect of the power valve assembly 5 on the outer cylinder 4 of the oil chamber when the pressure relief of the hydraulic oil is supported, so that the reliability of the connection between the outer cylinder 7 of the rupture disc and the outer cylinder 4 of the oil chamber is enhanced.

The principle of the invention is as follows: the upper joint 1 and the lower joint 1 of the safety joint are connected with downhole tools up and down to form a tool string, and the tool string is integrally lowered into a well. When sand is produced at a certain section in the well to cause the pipe string to be extruded and deformed and buried, and the whole tool string in the pipe string is lowered to the section, the blocking or lower joint 14 is used for simultaneously burying the tools in the process of passing through the section, the buried part and the non-buried part need to be released through the safety joint, the non-buried part is lifted up after being released, and the tools in the part are recovered, so that the tool loss is reduced. After a tool at the lower part of the lower joint 14 is buried, liquid pressure is pumped between the outer circle of the safety joint and the pipe column, when a certain pressure value is reached, the rupture disc 16 is ruptured, the liquid pressure enters the second channel 102 and pushes the balance piston 8 to move towards the upper joint, further the lock ring 6 is pushed, the lock ring 6 pushes the sealing head 5b away instantly, hydraulic oil in the cavity 204 is discharged into the second channel 102 under the action of the self gravity of the upper core shaft 2 and the lower core shaft 9, the pressurizing is continuously injected into the second channel 102, the liquid pressure pushes the top end of the lower core shaft 9 to move downwards, when the pressure reaches a rated value of the fracture of the cylindrical structure 15a and the boss 15b of the pressing sleeve 15, the boss 15b is fractured at the joint of the cylindrical structure 15a under the support of the first shoulder 14a, the cylindrical structure 15a is continuously pushed into the sliding channel 14b, and the second V-shaped groove 9a is moved to a position horizontally aligned with the claw rod 35, each claw rod 35 retracts into the second V-shaped groove 9a by means of the inward elasticity of the claw rod, so that the first V-shaped groove 35a releases the limit of the first V-shaped protrusion 13a, namely, the connection and fixation of the outer locking claw cylinder 10 and the outer connecting cylinder 13 are released, meanwhile, the locking groove 9b corresponds to the locking block 11, the locking block 11 is pushed into the locking groove 9b under the action of the spring 12, the lower core shaft 9 and the outer locking claw cylinder 10 form a fixed whole, the lifting action of the first protrusion 2a on the upper core shaft 2 on the locking nut and the outer oil chamber cylinder 4 is achieved, the whole safety joint is lifted through the upper joint 1, the outer connecting cylinder 13 and the outer locking claw cylinder 10 are separated, the releasing operation is completed, and then the upper joint 1 is lifted, and the tool which is not buried is lifted out of the well.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The utility model provides a RD type safety joint, includes upper mandrel (2), upper mandrel (2) have the straight-bar construction that runs through passageway (201) for inside upper mandrel (2) top and bottom have connected gradually upper joint (1) and lower mandrel (9), its characterized in that: an outer circle of the upper mandrel (2) is movably sleeved with an oil chamber outer cylinder (4), a rupture disc outer cylinder (7) and a locking claw outer cylinder (10) which are fixedly connected in sequence along the direction of the upper joint (1) towards the lower mandrel (9), the bottom end of the locking claw outer cylinder (10) is movably connected with a connecting outer cylinder (13) which can be separated from the locking claw outer cylinder, the bottom end of the connecting outer cylinder (13) is fixedly connected with a lower joint (14), a hydraulic locking device which is used for locking the upper mandrel (2) relative to the oil chamber outer cylinder (4) is arranged between the outer circle of the upper mandrel (2) and the oil chamber outer cylinder (4), an unlocking mechanism which acts on the hydraulic locking device and enables the upper mandrel (2) to move relative to the oil chamber outer cylinder (4) is arranged on the rupture disc outer cylinder (7), a pressing sleeve (15) which is used for connecting the outer cylinder (13) and the locking claw outer cylinder (10) to be separated from a release is arranged in the lower joint (14), the pressing sleeve (15) has a rated fracture pressure;

the hydraulic locking device comprises a cavity (204) formed by the excircle of the upper mandrel (2) and the inner hole of the oil chamber outer cylinder (4), one end of the cavity (204) close to the upper joint (1) is sealed, the other end of the cavity is provided with a first channel (101) communicated with the unlocking mechanism, one end of the cavity (204) close to the first channel (101) is internally provided with a power valve assembly (5), the power valve assembly (5) is matched with the unlocking mechanism to open and close the cavity (204) and the first channel (101), and the parts of the cavity (204) at one ends of the power valve assembly (5) and the cavity (204) close to the upper joint (1) are filled with liquid locking media under the condition that the lower joint (14) is not released from the lower mandrel (9);

an oil filling port (205) is formed in the oil chamber outer cylinder (4) corresponding to the cavity (204), and a lower oil filling plug (17) and an O-shaped ring (26) for opening and closing the oil filling port (205) in a sealing manner are arranged in the oil filling port.

2. An RD-type safety joint according to claim 1, wherein: the unlocking mechanism comprises a second channel (102) reserved between the outer circle of the upper mandrel (2) and the inner hole of the outer rupture disc barrel (7), the second channel is communicated with the first channel (101), a rupture disc (16) communicated with the second channel (102) is arranged on the wall of the outer rupture disc barrel (7), and the second channel (102) is far away from one end of the first channel (101) and is sealed at the top end of the lower mandrel (9).

3. An RD-type safety joint according to claim 2, wherein: the bottom end of the outer lock claw cylinder (10) is provided with a releasing mechanism which is integrally of an elastic claw structure and specifically comprises claw rods (35) which are arranged at the bottom end of the outer lock claw cylinder (10) at intervals along the circumferential direction and have hammer-head-shaped structures, the outer circle of each claw rod (35) is provided with a first V-shaped groove (35a) for limiting the outer connecting cylinder (13), a first V-shaped bulge (13a) matched with the first V-shaped groove (35a) for limiting is arranged on the connecting outer cylinder (13), a second V-shaped groove (9a) which has a certain width, is used for retracting the claw rod (35) and is released from limiting with the connecting outer cylinder (13) is arranged on the excircle of the lower mandrel (9), in a state where the lower joint (14) is not released from the lower spindle (9), the second V-shaped groove (9a) is positioned on one side, close to the upper joint (1), of the claw rod (35).

4. A RD-type safety joint according to claim 3, wherein: the pressing sleeve (15) is integrally a cylindrical structure (15a) with an opening at one side, a boss (15b) extends outwards from the end part of the cylindrical structure (15a) at the opening side, the bottom end of the lower mandrel (9) is pressed against the inner bottom surface of the cylindrical structure (15a), and a first shoulder (14a) used for supporting the boss (15b) and a sliding channel (14b) used for breaking the cylindrical structure (15a) and the boss (15b) are arranged in the lower joint (14).

5. An RD-type safety joint according to claim 4, wherein: the oil chamber outer barrel (4) is connected with a limiting block (3) used for limiting the upper core shaft (2) in a one-way mode towards the direction of the upper joint (1), and a first protrusion (2a) matched with the limiting block (3) is arranged on the upper core shaft (2).

6. An RD-type safety joint according to claim 5, wherein: the power valve assembly (5) comprises a shell (51) and a first through hole (501), a second through hole (502) and a third through hole (503) which are communicated with each other in the shell (51), a pressure spring (5a) and a sealing head (5b) with one end movably penetrating through the third through hole (503) are sequentially arranged in the second through hole (502), one end of the sealing head (5b) extends into the first channel (101) under the action of the pressure spring (5a), and a second shoulder (4a) used for limiting the whole power valve assembly (5) is arranged in the oil chamber outer barrel (4).

7. An RD-type safety joint according to claim 6, wherein: a locking ring (6) is movably arranged in the first channel (101), a third channel (103) is arranged between an inner hole of the locking ring (6) and the outer circle of the upper core shaft (2), the end of the locking ring (6) is abutted against the end of the sealing head (5b) in the hydraulic locking state of the upper core shaft (2) and can push the sealing head (5b) to break away from the sealing effect on the third through hole (503), and a one-way back-buckling thread matching structure in the same direction as the limiting block (3) is arranged between the outer circle of the locking ring (6) and the inner hole of the oil chamber outer barrel (4).

8. An RD-type safety joint according to claim 7, wherein: a balance piston (8) is movably arranged in the second channel (102), one end of the balance piston (8) abuts against one end, away from the sealing head (5b), of the locking ring (6) after moving, and a third shoulder (7a) for unidirectionally limiting the direction of the balance piston (8) towards the lower joint (14) is arranged on an inner hole of the rupture disc outer cylinder (7) on one side, close to the oil chamber outer cylinder (4), of the rupture disc (16).

9. An RD-type safety joint according to claim 8, wherein: the bottom of the outer barrel (7) of the rupture disc is inlaid with a locking block (11), a locking groove (9b) which is matched with the locking block (11) to lock the lower mandrel (9) after releasing with the outer barrel (7) of the rupture disc is formed in the lower mandrel (9), the locking block (11) is close to one side of the outer barrel (10) of the locking claw is inlaid with a spring (12) which is used for pushing the locking block to the locking groove (9 b).