Differential pressure sliding sleeve

Abstract

The utility model relates to the field of valve devices of well holes or wells, in particular to a differential pressure sliding sleeve. The differential pressure sliding sleeve comprises a bearing cylinder and an inner cylinder assembled in the bearing cylinder in a sliding mode, the lower end of the inner cylinder is provided with an elastic hook claw, the elastic hook claw comprises a finger part connected with the lower end of the inner cylinder and a hook part arranged at the tail end of the finger part, and the upper side face of the hook part is a wedge face inclining downwards from the end close to the finger part to the other end. In the process that the inner cylinder moves downwards to the avoiding position, the elastic hook claws are opened at the positioning steps, hook the inner wall face of the bearing cylinder and prevent the inner cylinder from moving upwards, when the differential pressure sliding sleeve needs to be recycled, the wedge faces of the hook parts can guide the inner cylinder to move upwards to a certain degree, and when a worker exerts large lifting force on the inner cylinder, the inner cylinder is prevented from moving upwards. And a worker can conveniently release the cooperation between the elastic claw and the positioning step, the elastic claw cannot deform, and the problem that the elastic claw and the latch hook step are difficult to separate is solved.

Description

Technical Field

[0001] The utility model relates to the field of valve devices for wellbores or wells, in particular to a differential pressure sliding sleeve. Background Art

[0002] Oil well fracturing is an important measure to increase the production of oil and gas wells and water injection wells. The oil recovery rate and production can be significantly improved through fracturing operations, especially for oil layers with low permeability. Fracturing technology is widely used in oil well development at home and abroad and has become an indispensable part of field development.

[0003] The differential pressure sleeve is widely used in oil and gas field fracturing completion operations, especially in staged fracturing operations. The differential pressure sleeve is a sleeve device controlled by pressure difference. It mainly uses the driving force generated by the pressure difference between the inside and outside of the pipe to open and close the sleeve, and then provides a working channel for the fracturing operation. In the fracturing operation of oil and gas wells, the differential pressure sleeve can ensure that the fracturing fluid is accurately injected into the target formation, improving the efficiency and success rate of the fracturing operation.

[0004] The pressure differential sleeve uses the fact that the area of ​​the axial upper end face of the inner cylinder is larger than the area of ​​the axial lower end face to generate a pressure difference at both axial ends of the inner cylinder, so that the inner cylinder moves downward to shear the shear pin, and then open the fracturing channel on the outer cylinder (i.e., the receiving cylinder). After the fracturing channel is opened, it is necessary to inject fracturing fluid into the channel. During this process, the fracturing channel needs to be kept open, but the inner cylinder may be affected by the bottom hole pressure during operation, causing the fracturing channel to close. Regarding the above problems, the prior art, such as the utility model patent with authorization announcement number CN217055102U and authorization announcement date 2022.07.26, discloses a pressure differential sleeve opened by absolute pressure difference, including an upper joint, an inner cylinder, a receiving cylinder, and a lower joint. The inner cylinder is slidably received in the receiving cylinder and is sealed with the inner wall of the receiving cylinder. When the inner cylinder moves downward, the shear pin is sheared to open the fracturing channel. An elastic claw is provided at one end of the inner tube near the lower joint, and a locking hook step is provided on the inner wall of the receiving tube near the lower joint. When the inner tube moves downward, the elastic claw cooperates with the locking hook step to prevent the inner tube from closing the sliding sleeve due to the bottom hole pressure. However, since the matching surface of the elastic claw and the locking hook step is a plane, a specific tool is required to separate the elastic claw from the locking hook step when the pressure differential sliding sleeve needs to be recycled, which is inconvenient to operate. When the staff applies a large lifting force to the inner tube, the matching part of the elastic claw and the locking step is easily deformed by force, which is not conducive to the recycling of the pressure differential sliding sleeve. Utility Model Content

[0005] The utility model aims to provide a differential pressure sleeve, which is used to solve the problem in the prior art that the elastic claw and the lock hook step are difficult to separate.

[0006] To achieve the above-mentioned purpose, the technical solution of the pressure differential sleeve provided by the utility model is: a pressure differential sleeve, including a receiving tube and an inner tube slidably assembled in the receiving tube, the lower end of the inner tube is provided with an elastic hook claw, the inner wall surface of the receiving tube is provided with a positioning step for stopping the elastic hook claw, the inner tube has a closing position for closing the flow hole of the receiving tube and an escape position below the closing position for opening the flow hole of the receiving tube in the receiving tube, the elastic hook claw is spread open when the inner tube is in the escape position and hooks the inner wall of the receiving tube through the positioning step to prevent the inner tube from moving upward due to the bottom hole pressure, the elastic hook claw includes a finger connected to the lower end of the inner tube and a hook portion provided at the end of the finger portion, the upper side surface of the hook portion is a wedge surface inclined downward from one end close to the finger portion to the other end.

[0007] Beneficial effect: The utility model improves the pressure differential sleeve in the prior art. By means of the elastic hook claw arranged at the lower end of the inner cylinder and the positioning step on the inner wall surface of the receiving cylinder, the elastic hook claw is stretched at the positioning step and hooks the inner wall surface of the receiving cylinder during the process of the inner cylinder moving downward to the avoidance position. When the inner cylinder has a tendency to move upward due to the bottom hole pressure, the positioning step can stop the elastic hook claw and prevent the inner cylinder from moving upward to the closed position due to the bottom hole pressure. When the pressure differential sleeve needs to be recycled, the wedge surface of the hook portion can guide the inner cylinder to move upward to a certain extent. When the staff applies a large lifting force to the inner cylinder, it is convenient for the staff to release the cooperation between the elastic hook claw and the positioning step, and the elastic hook claw will not be deformed, thereby solving the problem of the difficulty in separating the elastic claw and the locking hook step.

[0008] Furthermore, a plurality of the elastic hooks are arranged at intervals in the circumferential direction of the inner tube, and the positioning step is formed by an upper groove wall of a groove arranged along the circumferential direction of the receiving tube.

[0009] Furthermore, the groove is an annular groove arranged around the inner wall surface of the receiving tube.

[0010] Furthermore, a mounting hole is provided on the inner cylinder, a crushing piece is installed in the mounting hole, the flow hole on the receiving cylinder corresponds to the crushing piece, a shear pin is provided at the contact position between the inner cylinder and the receiving cylinder, the shear pin is sheared when the pressure of the inner cylinder reaches a first set pressure value, the crushing piece is opened when the pressure of the inner cylinder reaches a second set pressure value, and the first set pressure value is less than the second set pressure value.

[0011] Furthermore, the crushing piece is fixedly installed in the mounting hole by means of threads, and a sealing member is provided between the crushing piece and the mounting hole.

[0012] Furthermore, the opening pressure difference of the crushing piece from the inner cylinder to the receiving cylinder is smaller than the opening pressure difference from the receiving cylinder to the inner cylinder.

[0013] Furthermore, sealing members are provided at the upper and lower ends of the crushing piece and the shear pin, respectively.

[0014] Furthermore, a limiting structure is provided between the inner tube and the receiving tube to prevent the inner tube from escaping from the receiving tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of the pressure differential sleeve provided by the utility model.

[0016] In the figure: 1. upper joint; 11. shear pin; 2. inner tube; 21. mounting hole; 22. crushing piece; 23. annular boss; 24. elastic hook; 25. finger; 26. hook; 3. receiving tube; 31. flow hole; 32. annular raised part; 33. positioning step; 4. lower joint; 5. sealing member. DETAILED DESCRIPTION

[0017] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0018] In the prior art, after the pressure differential sleeve moves downward in the inner tube to open the flow hole on the receiving tube, the inner tube recovers the bottom hole pressure and moves upward. Once the inner tube moves to the position to close the flow hole on the receiving tube, the fracturing operation is interrupted, which will affect the completion operation of the oil well.

[0019] Therefore, the utility model provides a pressure differential sleeve, in which the lower end of the inner tube is provided with an elastic hook claw, and the inner wall surface of the receiving tube is provided with a positioning step, so that when the inner tube descends to the avoidance position to make way for the flow hole on the receiving tube, the elastic hook claw is stretched out and stopped by the positioning step, thereby preventing the inner tube from moving up due to the bottom hole pressure, solving the problem in the prior art that the inner tube is easily pressed up to block the fracturing channel.

[0020] The overall design concept of the pressure differential sleeve provided by the utility model is:

[0021] like Figure 1As shown, the differential pressure sleeve of the utility model includes a receiving tube 3 and an inner tube 2 slidably assembled in the receiving tube 3. The inner tube 2 has a closed position in the receiving tube 3 for closing the flow hole 31 of the receiving tube 3 and a evasion position below the closed position for opening the flow hole 31 of the receiving tube 3. When the inner tube 2 is in the evasion position, the fracturing fluid can enter the fracturing formation from the flow hole 31 of the receiving tube 3, thereby performing a fracturing operation. An elastic hook 24 is provided at the lower end of the inner tube 2, and a positioning step 33 is provided on the inner wall surface of the receiving tube 3. The positioning step 33 can stop the elastic hook 24. The elastic hook 24 can be opened and hooked on the inner wall of the receiving tube 3 through the positioning step 33 when the inner tube 2 moves to the evasion position. The positioning step 33 can stop the elastic hook 24 when it tends to move upward, thereby preventing the inner tube 2 from moving upward due to the bottom hole pressure. The elastic hook 24 includes a finger 25 connected to the lower end of the inner tube 2 and a hook 26 arranged at the end of the finger 25. The upper side of the hook 26 is a wedge surface that is inclined downward from one end close to the finger 25 to the other end. The finger 25 is arranged vertically. When in use, the hook 26 is elastically pressed against the inner wall surface of the receiving tube 3, thereby hooking the inner wall surface of the receiving tube 3. When the elastic hook 24 moves upward, the hook 26 is stopped by the positioning step 33, thereby locking the inner tube 2 in the avoidance position. The wedge surface of the hook 26 is inclined downward from one end close to the finger 25 to the other end. When the staff wants to release the lock on the inner tube 2, the wedge surface can make the staff conveniently allow the positioning step 33 to release the blocking of the hook 26. The whole process is relatively labor-saving. The staff does not need to use specific tools to overcome the elastic force of the elastic hook 24. It only needs to apply a large upward lifting force to the inner tube 2. Unlocking is relatively convenient, and the elastic hook will not be deformed, thereby increasing the service life of the differential pressure sleeve.

[0022] Based on the overall introduction of the differential pressure sleeve of the utility model above, a more specific embodiment is provided below on the basis of the overall introduction:

[0023] like Figure 1 As shown, multiple elastic hooks 24 are arranged at intervals in the circumferential direction of the inner cylinder 2, and the positioning step 33 is formed by the upper groove wall of the groove arranged along the circumferential direction of the receiving cylinder 3. The multiple elastic hooks 24 have multiple force application points, which increases the firmness of the elastic hooks 24 and the positioning step 33, and further prevents the inner cylinder 2 from moving up. The groove is an annular groove arranged around the inner wall surface of the receiving cylinder 3. The inner cylinder 2 may rotate axially during the downward movement, resulting in a change in the circumferential position of the elastic hook 24, while the annular groove on the circumferential direction of the receiving cylinder 3 allows the elastic hook 24 to enter in any case, thereby improving the fault tolerance of the groove.

[0024] like Figure 1As shown, the upper and lower ends of the receiving tube 3 are respectively connected with an upper joint 1 and a lower joint 4 for connecting with the downhole pipe string, and both ends of the receiving tube 3 are configured as negative step-shaped connecting buckles, and the upper joint 1 and the lower joint 4 are configured as positive step-shaped connecting buckles. In other embodiments, the two ends of the receiving tube 3 can also be configured as positive step-shaped connecting buckles, and the corresponding upper joint 1 and the lower joint 4 are configured as negative step-shaped connecting buckles.

[0025] In order to ensure the sealing performance of the upper joint 1 and the lower joint 4 with the receiving tube 3, sealing members 5 are respectively provided between the connecting surfaces of the upper joint 1, the lower joint 4 and the receiving tube 3. A sealing groove is provided on the positive step-shaped connecting buckle of the upper joint 1 and the lower joint 4 and on the axial inner side of the end surface, and the sealing member 5 is installed in the sealing groove. Preferably, the sealing member 5 adopts an O-ring. In other embodiments, the sealing groove can also be provided on the receiving tube 3. An overflow hole 31 is provided at one end of the receiving tube 3 close to the upper joint 1, and the overflow hole 31 is provided on the side wall of the receiving tube 3. A plurality of overflow holes 31 are provided and are provided at the same axial position of the receiving tube 3, and the overflow holes 31 are evenly spaced in the circumferential direction of the receiving tube 3. In other embodiments, the overflow hole 31 can be provided as a strip-shaped through hole extending in the axial direction. An annular boss 23 extending radially outward is provided at one end of the inner tube 2 close to the upper joint 1, so that the area of ​​the axial upper end surface of the inner tube 2 is larger than the area of ​​the axial lower end surface. When pressurized, a pressure difference is generated at the upper and lower ends of the inner tube 2, providing downward pressure to the inner tube 2 to cause it to move downward.

[0026] The inner tube 2 is provided with a mounting hole 21, and a crushing piece 22 is installed in the mounting hole 21. The flow hole 31 on the receiving tube 3 corresponds to the position of the crushing piece 22. When the inner tube 2 cannot move downward, the crushing piece 22 is opened to open the fracturing channel. In the actual working process, the inner tube 2 may encounter resistance and cannot move downward. At this time, the crushing piece 22 on the inner tube 2 can be opened. After opening, the flow hole 31 on the receiving tube 3 is opened, and the fracturing fluid can enter the fracturing formation for fracturing operations, which can improve the fault tolerance of the differential pressure sleeve. The crushing piece 22 is fixedly installed in the mounting hole 21 by a thread, and a sealing member is provided between the crushing piece 22 and the mounting hole 21. The sealing member can ensure the sealing performance between the crushing piece 22 and the mounting hole 21. The sealing member is specifically an O-ring arranged around the crushing piece 22. In other embodiments, the crushing piece 22 can be installed in other ways, such as welding, bolting, etc.

[0027] Preferably, the crushing piece 22 is opened by the internal and external pressure difference, the external pressure is the formation pressure, the internal pressure is the pressure of the working fluid in the pipe string, the opening pressure difference of the crushing piece 22 from the inner tube 2 to the receiving tube 3 is less than the opening pressure difference from the receiving tube 3 to the inner tube 2, that is, the opening pressure difference of the crushing piece 22 from the inside to the outside is less than the opening pressure difference from the outside to the inside, and when the internal pressure of the crushing piece 22 is greater than the external pressure and the internal and external pressure difference reaches the set value, the crushing piece 22 is opened. This setting can prevent the crushing piece 22 from opening first due to the pressure in the fracturing formation, resulting in pressure relief during the pressure process. In addition, due to the high cost of the crushing piece 22, the crushing piece 22 is set as the second layer of guarantee for opening the fracturing channel. If the crushing piece 22 is opened when the shear pin 11 is not cut off, it will lead to higher costs during the fracturing operation.

[0028] A shear pin 11 is provided at the contact portion between the inner tube 2 and the receiving tube 3. A through hole for installing the shear pin 11 is provided on the side wall of the receiving tube 3, and a mounting groove corresponding to the through hole is provided on the outer surface of the inner tube 2. The shear pin 11 passes through the through hole and is installed in the mounting groove, so that the inner tube 2 and the receiving tube 3 form a fixed connection at the blocking position. The shear pin 11 is sheared when the pressure of the inner tube 2 reaches the first set pressure value, and the crushing piece 22 is opened when the pressure of the inner tube 2 reaches the second set pressure value. The first set pressure value is less than the second set pressure value. In this way, when the pressure of the inner tube 2 reaches the first set value, the shear pin 11 is sheared, and the fixation of the inner tube 2 is released, and the inner tube 2 can move downward to open the flow hole 31. When the pressure of the inner tube 2 reaches the first set value, the shear pin 11 is sheared, but the inner tube 2 does not move downward, it means that the inner tube 2 encounters resistance. At this time, it is necessary to continue to pressurize to the second set pressure value, and the crushing piece 22 is opened to open the flow hole 31 and open the fracturing channel.

[0029] like Figure 1As shown, an annular protrusion 32 extending radially inward is provided on the inner wall surface of the receiving tube 3, the outer diameter of the annular boss 23 of the inner tube 2 is set to be the same as the inner diameter of the receiving tube 3, and the inner diameter of the annular protrusion 32 is set to be the same as the outer diameter of the inner tube 2, so that the inner tube 2 can move downward along the receiving tube 3. The distance between the axial upper end of the annular protrusion 32 and the axial lower end of the annular boss 23 is greater than the distance from the annular boss 23 to the lowest end of the flow hole 31, so as to ensure that the flow hole 31 on the receiving tube 3 can be fully opened when the inner tube 2 moves downward. The axial upper end surface of the annular protrusion 32 and the axial lower end surface of the annular boss 23 form a limiting structure. In the process of the inner tube 2 moving downward, the axial upper end surface of the annular protrusion 32 blocks the axial lower end surface of the annular boss 23 to prevent the inner tube 2 from moving too far and falling out of the receiving tube. The axial upper end of the annular protrusion 32 is located above the shear pin 11, and the axial lower end of the annular boss 23 is located below the flow hole 31. Of course, in other embodiments, the axial upper end of the annular protrusion 32 and the axial lower end of the annular boss 23 are both located below the shear pin 11.

[0030] In order to ensure better sealing performance, seals 5 are provided at the upper and lower ends of the shear pin 11 and the crushing piece 22, and sealing grooves are provided at the upper and lower ends of the shear pin 11 and the crushing piece 22 on the outer surface of the inner tube 2. The seals 5 are installed in the sealing grooves. The seals 5 can effectively ensure the sealing performance between the inner tube 2 and the receiving tube 3, thereby improving the working performance of the differential pressure sleeve. In addition, the seal 5 is provided at the lower end of the shear pin 11 so that the lower part of the shear pin 11 is sealed, which can avoid the influence of formation water on the shear pin 11, thereby reducing the possibility that the inner tube 2 encounters resistance and cannot move downward. Preferably, the seal 5 is an O-ring. In other embodiments, the sealing groove can also be provided on the inner wall of the receiving tube 3.

[0031] During the actual construction process, firstly, pressure is applied to the downhole tubing. At this time, the inner tube 2 on the pressure differential sleeve tends to move downward due to the pressure difference. At this time, pressure is continued until the pressure reaches the first set pressure value of the shear pin 11. The shear pin 11 is cut off to release the fixation of the inner tube 2. The inner tube 2 moves downward to the avoidance position to expose the flow hole 31 on the receiving tube 3. At the same time, the elastic hook 24 at the lower end of the inner tube 2 hooks the positioning step provided on the inner wall surface of the receiving tube 3. The positioning step 33 stops the elastic hook 24 to prevent the inner tube 2 from moving upward to the blocking position.

[0032] However, in the actual working process, the inner tube 2 may get stuck and unable to move downward. In this case, the pressure is continued. When the pressure in the inner tube 2 reaches the second set pressure value, the crushing piece 22 opens, and the fracturing channel is opened. Subsequent fracturing operations can be carried out.

[0033] After the fracturing operation is completed, when the differential pressure sleeve needs to be recycled, the wedge surface on the elastic hook 24 can be used to conveniently move the inner tube 2 to the blocking position, and then the crushing piece 22 or the shear pin 11 can be installed to carry out the next work.

[0034] It should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0035] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the description and drawings of the present invention shall be included in the protection scope of the present invention.

Claims

1. A differential pressure sleeve, characterized in that: It includes a receiving tube and an inner tube slidably assembled in the receiving tube, the lower end of the inner tube is provided with an elastic hook claw, the inner wall surface of the receiving tube is provided with a positioning step for stopping the elastic hook claw, the inner tube has a closing position for closing the flow hole of the receiving tube and an escape position below the closing position for making way for the flow hole of the receiving tube, the elastic hook claw is spread open and hooks the inner wall of the receiving tube through the positioning step when the inner tube is in the escape position to prevent the inner tube from moving upward due to the bottom hole pressure, the elastic hook claw includes a finger connected to the lower end of the inner tube and a hook portion provided at the end of the finger portion, the upper side surface of the hook portion is a wedge surface inclined downward from one end close to the finger portion to the other end.

2. The differential pressure sleeve according to claim 1, characterized in that: A plurality of elastic hooks are arranged at intervals in the circumferential direction of the inner tube, and the positioning step is formed by an upper groove wall of a groove arranged along the circumferential direction of the receiving tube.

3. The differential pressure sleeve according to claim 2, characterized in that: The groove is an annular groove arranged around the inner wall surface of the receiving tube.

4. The differential pressure sleeve according to any one of claims 1 to 3, characterized in that: The inner cylinder is provided with a mounting hole, a crushing piece is installed in the mounting hole, the flow hole on the receiving cylinder corresponds to the crushing piece, a shear pin is provided at the contact position between the inner cylinder and the receiving cylinder, the shear pin is cut off when the pressure of the inner cylinder reaches a first set pressure value, and the crushing piece is opened when the pressure of the inner cylinder reaches a second set pressure value, and the first set pressure value is less than the second set pressure value.

5. The differential pressure sleeve according to claim 4, characterized in that: The crushing piece is fixedly installed in the installation hole through a thread, and a sealing member is arranged between the crushing piece and the installation hole.

6. The differential pressure sleeve according to claim 4, characterized in that: The opening pressure difference of the crushing piece from the inner cylinder to the receiving cylinder is smaller than the opening pressure difference from the receiving cylinder to the inner cylinder.

7. The differential pressure sleeve according to claim 5, characterized in that: The opening pressure difference of the crushing piece from the inner cylinder to the receiving cylinder is smaller than the opening pressure difference from the receiving cylinder to the inner cylinder.

8. The differential pressure sleeve according to claim 4, characterized in that: Seals are provided at the upper and lower ends of the crushing piece and the shear pin respectively.

9. The differential pressure sleeve according to any one of claims 5 to 7, characterized in that: Seals are provided at the upper and lower ends of the crushing piece and the shear pin respectively.

10. The differential pressure sleeve according to claim 9, characterized in that: A limiting structure is arranged between the inner tube and the receiving tube to prevent the inner tube from escaping from the receiving tube.

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