Hydraulic boosting device

Abstract

The utility model relates to the technical field of in-well pipe column drawing and jam releasing, in particular to a hydraulic boosting device. The hydraulic boosting device comprises an inner pipe and an outer pipe, an upper connecting structure is arranged at the upper end of the inner pipe, a lower connector is connected to the lower end of the outer pipe, an annulus is defined between the inner pipe and the outer pipe, a piston assembly is assembled in the annulus in a sealed mode and comprises a piston seat and a piston, the piston seat is fixedly connected with the inner pipe, and the piston is located above the piston seat and fixedly connected with the outer pipe. The inner pipe, the piston seat, the piston and the outer pipe jointly define a pressurizing cavity, the inner pipe and / or the piston seat are / is provided with a pressure transmitting hole, the outer pipe is provided with an exhaust channel, the inner pipe is provided with a ball seat below the pressure transmitting hole, the lower end of the inner pipe extends into the lower connector and is in sealing fit with the lower connector, and the inner pipe, the lower connector, the piston seat and the outer pipe jointly define a lower cavity. And a communicating hole for communicating the lower cavity with the outside is formed in the outer pipe. When a plurality of hydraulic boosting devices are connected in series for use, the jam releasing stroke can be increased, and the boosting effect is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of pulling and releasing stuck wellbore strings, in particular to a hydraulic force increasing device. Background Technique

[0002] In the middle and late stages of oilfield development, the injection-production well pattern needs to be adjusted. After long-term water injection in some oil wells, the downhole string will scale, corrode, and the formation will produce sand seriously, resulting in the phenomenon of the stuck string. It is necessary to release the stuck and fish out the downhole string for repair or replacement. When performing workover pulling and releasing stuck, there is a problem of insufficient pulling force. Or at the moment of releasing the stuck, the string stretches and rebounds, causing strong vibration impact on the surface lifting system, leading to a series of safety hazards. When performing major repair pulling and releasing stuck, for highly deviated wells, especially horizontal wells, when pulling strongly at the wellhead, the fishing string and the inner wall of the casing slide friction occurs, and most of the wellhead pulling force is lost by the friction force between the fishing string and the inner wall of the casing. The actual stuck releasing force acting on the stuck string is very small, resulting in difficult stuck releasing.

[0003] The Chinese invention patent application document with the application publication number CN112324378A discloses a string shock hydraulic force increasing stuck releasing device. The device includes a bidirectional shocker and a hydraulic force increasing device. The hydraulic force increasing device includes an inner pipe and an outer pipe sleeved outside the inner pipe. The inner pipe includes an upper central pipe, a multi-stage piston rod and other components. The upper end of the inner pipe is fixedly connected with an upper joint (equivalent to an upper connection structure). The outer pipe includes an outer sleeve, a multi-stage piston cylinder and other components. The lower end of the outer pipe is connected with a lower joint. An annular space is formed between the outer pipe and the inner pipe. Along the axial direction, multiple groups of piston assemblies are hermetically assembled at intervals in the annular space. The piston assembly includes a piston sleeve (equivalent to a piston) and a piston (equivalent to a piston seat). The piston sleeve is above the piston and fixedly connected with the outer pipe. The piston is fixedly connected with the inner pipe. The outer pipe, the inner pipe, the piston sleeve and the piston jointly enclose a pressurizing cavity. The piston is provided with a liquid inlet hole (equivalent to a pressure transmission hole) communicating the pressurizing cavity with the inner cavity of the inner pipe. A ball seat is arranged at the lower end of the inner pipe, and a steel ball (equivalent to a valve ball) for hermetically cooperating with the ball seat when being pressed is arranged in the ball seat. During application, the upper end of the upper joint is connected with a hydraulic anchor, and the lower end of the lower joint is connected with a fishing tool. Hydraulic pressure is pumped from the wellhead. The liquid enters each pressurizing cavity through each liquid inlet hole, thereby pushing each piston sleeve to move upward, and then driving the lower joint to move upward. Since the lower joint is fixedly connected with the fishing tool and the fishing tool catches the stuck string, an upward pulling force can be generated on the stuck string, so as to convert the hydraulic pressure into the stuck releasing force for upward pulling the stuck string, and realize the stuck releasing of the stuck string.

[0004] When the existing hydraulic booster is used individually, the axial movement distance between the inner tube and the outer tube is restricted by a certain stage of piston sleeve and the piston seats on its upper and lower sides, and the movement distance is the pipe sticking releasing stroke. In actual application, if the distance between the top of the stuck pipe string and the sticking point is long, a larger pipe sticking releasing stroke is required. To increase the pipe sticking releasing stroke, multiple hydraulic boosters need to be connected in series. The steel ball of the lowermost hydraulic booster is retained, and the steel balls of other hydraulic boosters are removed to create a downward pressure transmission channel, thereby doubling the pipe sticking releasing stroke. When multiple existing hydraulic boosters are connected in series, since there is a long distance between the lower end of the inner tube and the lower joint to meet the upward movement requirement of the outer tube, there is a large cavity inside the outer tube between the lower end of the inner tube and the lower joint, and the cross-sectional area of this cavity is large. Therefore, when pressure is applied to the hydraulic booster, a large downward force will be generated on the lower joint and then a large downward force on the outer tube. The liquid entering the pressure chamber generates an upward thrust on the piston sleeve, which drives the outer tube to move upward. Most of this upward thrust is lost by this large downward force, resulting in a greatly reduced upward force that can finally be generated on the outer tube, a small pulling force on the stuck pipe string, and a poor force increasing effect. Summary of the Invention

[0005] The purpose of the present invention is to provide a hydraulic force increasing device to solve the problem of poor force increasing effect when multiple existing hydraulic boosters are connected in series.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A hydraulic force increasing device includes an inner tube and an outer tube sleeved outside the inner tube. The upper end of the inner tube is provided with an upper connection structure for connecting a fishing string. The lower end of the outer tube is connected with a lower joint. An annular space is formed between the inner and outer tubes. A piston assembly is hermetically assembled in the annular space. The piston assembly includes a piston seat and a piston. The piston seat is fixedly connected with the inner tube. The piston is above the piston seat and fixedly connected with the outer tube. The inner tube, the piston seat, the piston and the outer tube jointly enclose a pressure chamber. The inner tube and / or the piston seat are provided with pressure transmission holes communicating the pressure chamber with the inner cavity of the inner tube. The outer tube is provided with an exhaust passage communicating the annular space above the piston with the outside. A ball seat for hermetically cooperating with a valve ball is provided on the inner tube below the pressure transmission hole. The lower end of the inner tube extends into the lower joint and they are hermetically cooperated. The inner tube, the lower joint, the piston seat and the outer tube jointly enclose a lower chamber. The outer tube is provided with a communication hole communicating the lower chamber with the outside.

[0008] Further, the ball seat is inside the lower joint.

[0009] Further, the lower end of the ball seat is close to the lower end outlet of the lower joint.

[0010] Further, the ball seat is separately arranged from the inner tube and is detachably connected.

[0011] Further, the communication holes are located at a position on the outer tube close to the lower joint.

[0012] Further, an upper joint is connected to the upper end of the inner tube, and the upper joint constitutes the upper connection structure. The inner tube and the outer tube achieve torque transmission through the upper joint.

[0013] Further, the upper joint and the outer tube achieve torque transmission through keyway fit.

[0014] Further, a convex key is provided on one of the upper joint and the outer tube, and a groove is provided on the other. The central angle corresponding to the groove is larger than the central angle corresponding to the convex key, so that they can rotate relative to each other in the circumferential direction, and when they rotate to the convex key contacts the groove wall, they form a stop fit in the circumferential direction to achieve torque transmission.

[0015] Further, the upper connection structure and the lower joint are provided with matching thread structures to achieve the series connection of two hydraulic boosting devices when the lower joint is threadedly connected to the upper connection structure of another hydraulic boosting device.

[0016] Further, the pressure transmission holes are provided on the tube wall of the inner tube and above the piston sleeve.

[0017] Beneficial effects: The hydraulic force - increasing device of the present utility model is an improved invention. When used individually, the upper end of the inner tube can be connected to the fishing string through the upper connection structure, and the lower end of the outer tube can be connected to the fishing tool through the lower joint. Pressurize from the wellhead to press the valve ball against the ball seat to achieve sealing. The liquid in the inner cavity of the inner tube enters the pressurizing cavity through the pressure - transmitting holes, thereby pushing the piston to move upward. The piston drives the outer tube and the lower joint to move upward. Since the lower joint is fixedly connected to the fishing tool and the fishing tool catches the stuck pipe string, an upward pulling force can be generated on the stuck pipe string, thus converting the hydraulic pressure into the unlocking force for pulling the stuck pipe string upward to achieve unlocking. When two or more hydraulic force - increasing devices are connected in series, only the valve ball is placed in the lowermost hydraulic force - increasing device, and no valve ball is provided in other hydraulic force - increasing devices to leave the pressure - transmitting channel. The main improvement of the hydraulic force - increasing device of the present utility model lies in that the lower end of the inner tube extends into the lower joint and the inner tube is in sealing fit with the lower joint. The inner tube, the lower joint, the piston seat, and the outer tube jointly enclose a lower chamber, and the lower chamber is an annular chamber. The outer tube is provided with a communication hole for communicating the lower chamber with the outside. When the outer tube moves upward, it squeezes the lower chamber, and the gas in the lower chamber is discharged through the communication hole to meet the upward movement requirement of the outer tube. Compared with the relatively large cavity between the lower end of the inner tube and the lower joint in the existing hydraulic booster, the cross - sectional area of this lower chamber is significantly smaller. In this way, when two or more hydraulic force - increasing devices are connected in series, compared with connecting two or more existing hydraulic boosters in series, when pressurizing the hydraulic force - increasing device, a smaller downward force is generated on the lower joint and thus a smaller downward force is generated on the outer tube. The liquid entering the pressurizing cavity generates an upward thrust on the piston and then drives the outer tube to move upward. The part of the upward thrust lost by this downward force is less, so a greater upward force can be generated on the outer tube, a greater pulling force is generated on the stuck pipe string, and the force - increasing effect is better. Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of the upper half of the hydraulic force - increasing device of the present utility model;

[0019] Figure 2 It is a schematic structural diagram of the lower half of the hydraulic force - increasing device of the present utility model;

[0020] Figure 3 It is a schematic diagram of torque transmission between the inner tube and the outer tube through the upper joint;

[0021] Figure 4 It is a schematic structural diagram of the upper joint;

[0022] Figure 5 For Figure 4 The sectional view taken along A - A in

[0023] Figure 6 It is a schematic structural diagram of the outer tube;

[0024] Figure 7 For Figure 6 Cross-sectional view taken along line B-B in

[0025] Figure 8 Schematic diagram of the hydraulic force increasing device of the present utility model being lowered into the well along with the fishing string

[0026] In the figure: 1. Upper joint; 1-1. Upper joint convex key; 1-2. Upper joint groove; 2. Inner pipe; 3. Outer pipe; 4. Sealing ring; 5. Piston; 6. Piston seat; 7. Exhaust passage; 8. Communication hole; 9. Pressure transmission hole; 10. Pressurizing cavity; 11. Lower chamber; 12. Lower joint; 12-1. Outer pipe convex key; 12-2. Outer pipe groove; 13. Ball seat; 14. Valve ball; 15. Hydraulic anchor; 16. Fishing tool; 17. Fish; 18. Hydraulic force increasing device Specific embodiments

[0027] The features and performance of the present utility model will be further described in detail below in conjunction with embodiments

[0028] The present utility model provides a hydraulic force increasing device, which is mainly used to solve the problem of poor force increasing effect when multiple existing hydraulic force boosters are connected in series. The basic inventive concept of the present utility model is: on the basis of the structure of the existing hydraulic force booster, further improvement is made by extending the inner pipe so that the lower end of the inner pipe extends into the lower joint and the two are hermetically fitted, thereby enabling the inner pipe, the lower joint, the piston seat and the outer pipe to jointly enclose a lower chamber with a relatively small cross-sectional area. In this way, when two or more hydraulic force increasing devices are connected in series and pressurized, a relatively small downward force will be generated on the lower joint and thus a relatively small downward force will be generated on the outer pipe. The liquid entering the pressurizing cavity will generate an upward thrust on the piston, which will drive the outer pipe to move upward. The part of the upward thrust lost by the downward force is less, so that a greater upward force can be generated on the outer pipe and a greater pulling force can be generated on the stuck pipe string, significantly improving the force increasing effect

[0029] Based on the above basic inventive concept, the embodiments of the hydraulic force increasing device of the present utility model will be introduced in detail below

[0030] As Figure 1-2As shown in the figure, the hydraulic boosting device includes an inner pipe assembly and an outer pipe assembly. The outer pipe assembly is sleeved outside the inner pipe assembly. The outer pipe assembly includes an outer pipe 3 and a lower joint 12 threadedly connected to the lower end of the outer pipe 3. The fishing tool 16 can be connected through the lower joint 12. The inner pipe assembly includes an inner pipe 2, an upper joint 1 and a ball seat 13. The upper joint 1 is threadedly connected to the upper end of the inner pipe 2. The upper joint 1 can be used to connect the fishing string. The ball seat 13 is threadedly connected to the lower end of the inner pipe 2 and is used for sealing cooperation with the valve ball 14. After the wellhead is pressured, the valve ball 14 is pressed against the ball seat 13 to achieve the sealing cooperation between the two. An annular space is formed between the inner pipe 2 and the outer pipe 3. A piston assembly is hermetically assembled in the annular space. The piston assembly includes a piston seat 6 and a piston 5. The piston seat 6 is fixedly connected to the inner pipe 2. A sealing ring 4 is provided on the outer peripheral surface of the piston seat 6 to achieve the sealing cooperation between the piston seat 6 and the outer pipe 3. The piston 5 is located above the piston seat 6 and is fixedly connected to the outer pipe 3. A sealing ring 4 is provided on the inner peripheral surface of the piston 5 to achieve the sealing cooperation between the piston 5 and the inner pipe 2. A sealing ring 4 is also provided at the position where the piston 5 is fixedly connected to the outer pipe 3 to prevent liquid leakage at the connection position. The inner pipe 2, the piston seat 6, the piston 5 and the outer pipe 3 together enclose a pressurizing chamber 10. A pressure transmission hole 9 communicating the pressurizing chamber 10 with the inner cavity of the inner pipe 2 is provided on the pipe wall of the inner pipe 2. The liquid in the inner pipe 2 enters the pressurizing chamber 10 through the pressure transmission hole 9 and acts on the piston 5 to push the piston 5 upward. An exhaust passage 7 communicating the annulus above the piston 5 with the outside is provided on the outer pipe 3. When the piston 5 moves upward, the gas in the annulus above the piston 5 is squeezed, and the gas is discharged through the exhaust passage 7 to ensure the smooth upward movement of the piston 5.

[0031] In this embodiment, there are two sets of piston assemblies. The two sets of piston assemblies are axially spaced in the annular space between the inner and outer pipes. For the lower set of piston assemblies, the annulus above its piston 5 is the annulus between the piston 5 of the lower set of piston assemblies and the piston seat 6 of the upper set of piston assemblies. An exhaust passage 7 communicating this annulus with the outside is provided on the pipe wall of the outer pipe 3. Preferably, the exhaust passage 7 is located at the position of the piston 5 of the outer pipe 3 close to the lower set of piston assemblies. The exhaust passage 7 communicates with the annulus at a position close to the bottom, so as to ensure a larger pipe sticking releasing stroke. For the upper set of piston assemblies, the annulus above its piston 5 is the annulus between the piston 5 of the upper set of piston assemblies and the upper joint 1. The upper end of the outer pipe 3 is sleeved outside the upper joint 1. A long groove communicating this annulus with the outside of the upper end of the outer pipe 3 is provided on the inner peripheral surface of the outer pipe 3. The long groove is the exhaust passage 7 communicating this annulus with the outside.

[0032] Both the inner tube 2 and the outer tube 3 are provided with multiple segments. Adjacent segments of the inner tube 2 are fixedly connected through a piston seat 6, and the piston seat 6 also serves as a coupling between adjacent segments of the inner tube 2. Adjacent segments of the outer tube 3 are fixedly connected through a piston 5, and the piston 5 also serves as a coupling between adjacent segments of the outer tube 3. The inner tube 2 and the piston seat 6, as well as the outer tube 3 and the piston 5, are connected by threads, which can be assembled on-site, and the number of piston groups to be connected can be independently selected according to needs, making the assembly more convenient and flexible. The multi-stage piston structure can double the pulling force and provide a large pipe-unsticking force at a relatively low internal pipe pressure. There is no limit to the number of piston groups during application, and the number of piston groups can be increased or decreased according to needs. In addition, the piston 5 and the piston seat 6 adopt a compact nested design, which can provide a large pipe-unsticking stroke with a relatively small total length of the tool.

[0033] As Figure 2 shown in the figure, the lower end of the inner tube 2 extends into the lower joint 12. A sealing ring 4 is provided on the lower joint 12 to achieve a sealed fit between the lower joint 12 and the inner tube 2. The inner tube 2, the lower joint 12, the piston seat 6 of the lowermost piston assembly, and the outer tube 3 together enclose a lower chamber 11. The outer tube 3 is provided with a communication hole 8 that communicates the lower chamber 11 with the outside. When the lower joint 12 moves upward, it squeezes the gas in the lower chamber 11, and the gas in the lower chamber 11 is discharged through the communication hole 8 to ensure the smooth upward movement of the lower joint 12 and the outer tube 3. The cross-sectional area of the lower chamber 11 is small, so when pressure is applied to the hydraulic force-increasing device, a relatively small downward force is generated on the lower joint 12 and thus a relatively small downward force is generated on the outer tube 3. The liquid entering the pressure chamber 10 generates an upward thrust on the piston 5, which in turn drives the outer tube 3 to move upward. The part of the upward thrust lost by this downward force is relatively small, so that a relatively large upward force can be ensured on the outer tube 3, and a relatively large pulling force can be generated on the stuck pipe string, with a good force-increasing effect.

[0034] Preferably, the communication hole 8 is located on the outer tube 3 near the lower joint 12, and the communication hole 8 communicates with the lower chamber 11 near the bottom, so as to ensure that the lower joint 12 has a relatively large upward stroke as much as possible, and thus ensure a relatively large pipe-unsticking stroke. Of course, in other embodiments, the communication hole 8 can also be moved upward by a certain distance.

[0035] In this embodiment, the ball seat 13 is separately arranged from the inner tube 2. The ball seat 13 is fixedly connected to the lower end of the inner tube 2. The inner tube 2 extends into the lower joint 12 and is in sealing fit with the lower joint 12. The ball seat 13 is located inside the lower joint 12. In this way, there is no need to consider the sealing fit between the ball seat 13 and the inner tube 2, which can simplify the structure and assembly relationship. In another embodiment, the ball seat 13 and the inner tube 2 are of an integral structure. The inner tube 2 has a sealing surface for sealing fit with the valve ball 14 inside. This sealing surface constitutes the ball seat 13. At this time, the ball seat 13 is located inside the lower joint 12, and the ball seat 13 is arranged as low as possible on the inner tube 2. It is possible to arrange more piston assemblies while ensuring the overall length of the inner tube 2 remains unchanged, increasing the pipe releasing force. Of course, the ball seat 13 can also be located above the lower joint 12. In this embodiment, the ball seat 13 is separately arranged from the inner tube 2 and is detachably connected, which is beneficial for processing and more convenient for assembly.

[0036] More preferably, the lower end of the ball seat 13 is close to the lower end outlet of the lower joint 12. The advantage is that the total length of the hydraulic force increasing device can be shortened on the premise that the pipe releasing stroke remains unchanged. Especially when two or more hydraulic force increasing devices are connected in series, the total length after series connection can be controlled not to be too long. Of course, in other embodiments, the ball seat 13 can also be located at the middle position or the upper position inside the lower joint 12.

[0037] The upper joint 1 and the lower joint 12 are provided with matching thread structures. An internal thread section is provided at the upper end of the upper joint 1, and an external thread section is provided at the lower end of the lower joint 12. When two hydraulic force increasing devices need to be connected in series, the lower joint 12 of one hydraulic force increasing device is directly thread-connected to the upper joint 1 of another hydraulic force increasing device through the thread structure, so as to realize the series connection of the two hydraulic force increasing devices. The connection is convenient and the total length after series connection of multiple hydraulic force increasing devices can be controlled.

[0038] In one embodiment of this embodiment, the pressure transmission hole 9 is arranged on the pipe wall of the inner tube 2 and above the piston seat 6, which is beneficial for processing. In other embodiments, the two inner tubes 2 are fixedly connected through the piston seat 6. The pressure transmission hole 9 can also be arranged on the piston seat 6, or through holes are respectively arranged at corresponding positions on the inner tube 2 and the piston seat 6, and the through holes on the inner tube 2 and the piston seat 6 are connected to each other, and the two together constitute the pressure transmission hole.

[0039] The outer tube 3 is sleeved outside the inner tube 2. The inner tube 2 and the outer tube 3 realize torque transmission through the upper joint 1. When the inner tube 2 rotates, it can transmit the torque to the outer tube 3 through the upper joint 1, driving the outer tube 3 to rotate. The lower end of the outer tube 3 is connected to the fishing tool 16 through the lower joint 12, so the torque can be transmitted to the fishing tool 16. Specifically, as Figure 3 shown, the upper joint 1 and the outer tube 3 realize torque transmission through keyway fit. As Figure 4-5As shown, on the outer circumferential surface of the lower end of the upper joint 1, upper joint keys 1-1 extending axially along the upper joint 1 are provided at intervals in the circumferential direction. There are four upper joint keys 1-1 and they are evenly distributed at intervals in the circumferential direction. Upper joint grooves 1-2 are formed between adjacent upper joint keys 1-1. As Figure 6-7 shown, on the inner circumferential surface of the outer tube 3, outer tube keys 12-1 extending axially along the outer tube 3 are provided at intervals. There are four outer tube keys 12-1 and they are evenly distributed at intervals in the circumferential direction. Outer tube grooves 12-2 are formed between adjacent outer tube keys 12-1. As Figure 3 shown in the figure, the upper joint keys 1-1 are inserted into the outer tube grooves 12-2. The central angle corresponding to the outer tube grooves 12-2 is larger than the central angle corresponding to the upper joint keys 1-1, so that the outer tube grooves 12-2 and the upper joint keys 1-1 can rotate relative to each other within a certain range in the circumferential direction. At the same time, the outer tube keys 12-1 are movably inserted into the upper joint grooves 1-2 along the circumferential direction. When the upper joint 1 rotates until the upper joint keys 1-1 contact the groove walls of the outer tube grooves 12-2 to form a circumferential stop, the groove walls of the upper joint grooves 1-2 contact the outer tube keys 12-1 at the same time, so that torque transmission can be realized.

[0040] The upper joint 1 and the outer tube 3 are made to realize torque transmission through keyway cooperation, and the central angle corresponding to the groove is made larger than the central angle corresponding to the key so that the two can rotate relative to each other within a certain range in the circumferential direction. The purpose of such a setting is to prevent the downhole dirt from easily filling and solidifying the groove when the groove is small. Once it is solidified, the outer tube 3 cannot move upward relative to the inner tube 2, resulting in the failure of hydraulic force increase. The torque of the fishing string is transmitted to the outer tube assembly through the upper joint 1 on the inner tube 2. The outer tube assembly has a larger diameter, so it can transmit a larger torque. In other embodiments, the upper joint 1 and the outer tube 3 can also realize torque transmission through a regular polygon cross-section. Of course, a torque transmission structure may not be provided between the inner tube 2 and the outer tube 3. At this time, the outer tube 3 can move upward relative to the inner tube 2, but the torque of the inner tube 2 cannot be transmitted to the outer tube 3.

[0041] During application, as Figure 8As shown, the upper end of the hydraulic booster 18 is connected to the salvage pipe string, and the lower end is connected to the salvage device 16 and then lowered into the well with the salvage pipe string. The salvage pipe string is connected with a hydraulic anchor 15. After the salvage device 16 captures the fallen fish 17, the pipe string is lifted up to a free hanging weight, and pressure is applied from the wellhead. The anchor claws of the hydraulic anchor 15 are opened to anchor the pipe string on the inner wall of the casing. After the hydraulic anchor 15 is sealed, the pipe string is lowered to a free hanging weight. At this time, under the action of liquid pressure, the valve ball 14 in the hydraulic booster 18 is pressed against the ball seat 13 to form a seal. The liquid in the pipe string enters the pressure chamber 10 through the pressure transmission hole 9 on the inner pipe 2, pushing the piston 5 upward. The piston 5 drives the outer pipe 3, the lower joint 12 and the salvage device 16 below to move upward, producing a pulling effect on the fallen fish 17. The multi-stage piston structure doubles the pulling force, gradually increasing the pressure in the pipe string on the ground until the fallen fish 17 is forcibly released. It should be noted that the fish falling 17 mentioned here is not limited to the stuck pipe string, but generally refers to the stuck objects in the well.

[0042] After the fish 17 is unstuck or the fish top is pulled off / detached, the outer tube 3 moves upward rapidly under the pressure until the connecting hole 8 and the pressure relief channel on the outer tube 3 exceed the piston seat 6 upward and the pressure chamber 10 is connected with the oil casing annulus to release the pressure. The pressure on the ground display drops, indicating that the unstuck stroke has been completed. If the fish top is pulled off without the fish catcher 16 being gripped during unstuck, the fish catch can be repeated.

[0043] When the jam cannot be released, the pressure in the pipe string is released to retract the anchor claws of the hydraulic anchor 15, release the anchor, and then rotate the salvage pipe string, the torque is transmitted to the inner pipe 2 and then transmitted to the outer pipe assembly and the salvage device 16 connected at the lower part through the upper joint 1, and the salvage device 16 is withdrawn.

[0044] When a hydraulic booster is used alone, the axial movement distance between the inner tube 2 and the outer tube 3 is limited by a certain level of piston 5 and the piston seats 6 on its upper and lower sides, and the movement distance is the jam-release stroke. If the distance from the fish top to the jam point is long and a larger jam-release stroke is required, multiple hydraulic boosters can be used in series, and only the valve ball 14 is retained on the bottom hydraulic booster, and the valve balls 14 of other hydraulic boosters are removed to make way for the downward pressure transmission channel. Since the outer tube assembly of the previous hydraulic booster is connected to the inner tube assembly of the next hydraulic booster, the pulling force remains unchanged after multiple hydraulic boosters are connected in series, and the jam-release stroke is doubled.

[0045] In one of the above embodiments, an upper joint is connected to the upper end of the inner tube, and the upper joint constitutes an upper connection structure for connecting the salvage pipe string. In other embodiments, the upper joint may not be provided, and a threaded structure may be directly provided on the upper end of the inner tube, and the inner tube is connected to the salvage pipe string through the threaded structure. In this case, the threaded structure is the upper connection structure.

[0046] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. The patent protection scope of the present utility model is subject to the claims. Any equivalent structural changes made by using the content of the specification and drawings of the present utility model shall similarly be included within the protection scope of the present utility model.

Claims

1. A hydraulic booster device, comprising an inner tube and an outer tube sleeved outside the inner tube, an upper connecting structure for connecting a salvage pipe string is provided at the upper end of the inner tube, a lower joint is connected at the lower end of the outer tube, an annulus is formed between the inner and outer tubes, a piston assembly is sealably assembled in the annulus, the piston assembly comprises a piston seat and a piston, the piston seat is fixedly connected to the inner tube, the piston is located above the piston seat and fixedly connected to the outer tube, the inner tube, the piston seat, the piston and the outer tube jointly form a pressurized chamber, a pressure transmission hole connecting the pressurized chamber with the inner chamber of the inner tube is provided on the inner tube and / or the piston seat, an exhaust passage connecting the annulus above the piston with the outside is provided on the outer tube, a ball seat for cooperating with a valve ball seal is provided on the inner tube below the pressure transmission hole, and the characteristics are as follows: The lower end of the inner tube extends into the lower joint and the two are sealed and matched. The inner tube, the lower joint, the piston seat and the outer tube together form a lower chamber. The outer tube is provided with a connecting hole connecting the lower chamber with the outside.

2. The hydraulic booster device according to claim 1, characterized in that: The ball seat is inside the lower joint.

3. The hydraulic booster device according to claim 2, characterized in that: The lower end of the ball seat is close to the lower end outlet of the lower joint.

4. The hydraulic booster device according to any one of claims 1 to 3, characterized in that: The ball seat and the inner tube are separately arranged and detachably connected.

5. The hydraulic booster device according to any one of claims 1 to 3, characterized in that: The communicating hole is located on the outer tube near the lower joint.

6. The hydraulic booster device according to any one of claims 1 to 3, characterized in that: The upper end of the inner tube is connected with an upper joint, which constitutes the upper connection structure, and the inner tube and the outer tube realize torque transmission through the upper joint.

7. The hydraulic booster device according to claim 6, characterized in that: The upper joint and the outer tube realize torque transmission through keyway cooperation.

8. The hydraulic booster device according to claim 7, characterized in that: One of the upper joint and the outer tube is provided with a convex key, and the other is provided with a groove. The central angle corresponding to the groove is greater than the central angle corresponding to the convex key, so that the two can rotate relative to each other in the circumferential direction. When the convex key rotates to contact the groove wall of the groove, the two form a stop fit in the circumferential direction to achieve torque transmission.

9. The hydraulic booster device according to any one of claims 1 to 3, characterized in that: The upper connection structure and the lower joint are provided with matching thread structures, so as to realize the serial connection of two hydraulic boosting devices when the lower joint is threadedly connected with the upper connection structure of another hydraulic boosting device.

10. The hydraulic booster device according to any one of claims 1 to 3, characterized in that: The pressure transmission hole is arranged on the tube wall of the inner tube and is located above the piston sleeve.

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