Setting adapter, ball seat assembly and fracturing ball recovery method

Abstract

Disclosed are a setting adapter, a ball seat assembly and a fracturing ball recovery method. The setting adapter comprises a push sleeve (1) and a release rod (2). The push sleeve has a ball seat abutting section (11), which is configured to abut against and connect to a ball seat. The passing direction of a one-way passage mechanism (3) is a direction extending from an axial outer side of the ball seat abutting section to an inner side thereof. After the ball seat completes setting, the release rod retracts into the push sleeve, and a first space (12) for accommodating a fracturing ball is provided between an end of the release rod, the ball seat abutting section and the one-way passage mechanism. When a fracturing ball recovery operation needs to be performed, the fracturing ball is pushed into the first space in the push sleeve by means of flowback, and the one-way passage mechanism restricts the fracturing ball from falling out of the push sleeve, thereby ensuring the reliability of fracturing ball recovery.

Description

A setting adapter, a ball seat assembly, and a method for recovering fracturing balls. Technical Field

[0001] This invention relates to the field of downhole tool technology, specifically to a setting adapter, a ball seat assembly, and a method for recovering fracturing balls. Background Technology

[0002] Current fracturing methods often employ perforation and seat assembly. To save on pumping fracturing balls and water, ball seats with pre-placed balls are used. However, this presents two risks: First, if the seal is not tight during verification after the ball seat is set, a new ball seat needs to be installed. This requires secondary pumping, but since there is no channel for pumping fluid in the wellbore, secondary pumping is not possible. Second, if the perforation fails due to the gun not igniting, the perforation gun needs to be pumped again for secondary pumping. Again, this is impossible because there is no channel for pumping fluid in the wellbore. To achieve secondary pumping, fracturing balls need to be captured and recovered. Current fracturing ball capture and recovery methods use specialized ball-collecting adapters or fracturing ball recovery devices. This method, which uses separately equipped fracturing balls, is complex and costly. Summary of the Invention

[0003] To address one of the problems in the prior art, this invention provides a setting adapter, a ball seat assembly, and a sealing ring for a fracturing ball recovery method.

[0004] The technical solution is as follows:

[0005] A seated adapter includes a pusher and a release lever;

[0006] The pusher has a ball seat abutment section, which is used to abut and connect with a ball seat. The ball seat abutment section is provided with a one-way passage mechanism for the fracturing ball to pass through in one direction. The passage direction of the one-way passage mechanism is the direction extending from the outer side of the axial direction of the ball seat abutment section to its inner side.

[0007] The drop stick has a ball seat connecting section, which passes through the one-way passage mechanism for fitting and connecting with the ball seat. After the ball seat is set, the drop stick retracts into the push tube. There is a first space between the end of the drop stick, the ball seat abutment section and the one-way passage mechanism to accommodate the fracturing ball.

[0008] The working principle and beneficial effects of this invention are as follows: After setting is completed using the setting adapter of this invention, the release lever retracts into the push cylinder, and there is a first space for accommodating the fracturing ball between the end of the release lever, the ball seat abutment section, and the one-way passage mechanism; when a secondary pumping operation is required, the fracturing ball is pushed back into the first space in the push cylinder by a backflow method. At the same time, the one-way passage mechanism restricts the fracturing ball from falling out of the push cylinder, ensuring the reliability of fracturing ball recovery.

[0009] Based on the above technical solution, the present invention can be further improved as follows.

[0010] Furthermore, the unidirectional passage mechanism is a single-layer mechanism, which is a spring sheet layer. The spring sheet layer has multiple spring sheets, and the aperture formed at the ends of the multiple spring sheets is smaller than the diameter of the fracturing ball. The ends of the multiple spring sheets extend obliquely away from the ball seat abutment section.

[0011] The beneficial effect of adopting the above-mentioned further solution is that the single-layer mechanism in which the ends of the multiple spring pieces extend inclined away from the ball seat abutment section achieves the effect of simple unidirectional restriction of the fracturing ball.

[0012] Based on the above technical solution, the present invention can be further improved as follows.

[0013] Furthermore, the spring has a first end and a second end. The first end is integrated with the outer ring to form an integral structure, and the outer ring is fixedly mounted on the ball seat abutment section. The second end extends obliquely away from the ball seat abutment section. The advantage of adopting the above-mentioned further solution is that making the first end an integral structure facilitates the installation of the entire one-way passage mechanism.

[0014] Based on the above technical solution, the present invention can be further improved as follows.

[0015] Furthermore, the unidirectional passage mechanism is a double-layer mechanism, including a spring sheet layer and a retaining ring layer. The spring sheet layer has multiple spring sheets, and the diameter of the holes formed at the ends of the multiple spring sheets is smaller than the diameter of the fracturing ball. The spring sheet layer is disposed on the axial inner side of the ball seat abutment section. The retaining ring layer has a through hole for the fracturing ball to pass through, and the diameter of the through hole is larger than the diameter of the fracturing ball. The retaining ring layer is disposed on the axial outer side of the ball seat abutment section.

[0016] The beneficial effects of adopting the above-mentioned further solution are: by setting a double-layer structure, the fracturing ball can pass through in the direction of extending from the outer side of the ball seat abutment section to its inner side, but cannot pass through in the opposite direction; at the same time, the retaining ring layer provides a reliable restraining effect.

[0017] Based on the above technical solution, the present invention can be further improved as follows.

[0018] Furthermore, the unidirectional passage mechanism is a variable-diameter helical spring structure. The diameter of the central hole in the variable-diameter helical spring structure is smaller than the diameter of the fracturing ball, and the small end of the variable-diameter helical spring extends obliquely away from the ball seat abutment section. The beneficial effect of adopting the above-mentioned further solution is that: the central through hole is smaller than the fracturing ball, and the fracturing ball enters the variable-diameter helical spring structure from the ball seat abutment section. When the impact force of the backflow flow on the fracturing ball is large, the diameter of the central through hole becomes larger, and the fracturing ball smoothly passes through the variable-diameter helical spring structure into the first space; due to the variable-diameter helical spring structure, the fracturing ball will not fall out of the first space.

[0019] Based on the above technical solution, the present invention can be further improved as follows.

[0020] Furthermore, it also includes a second space for accommodating the fracturing ball, wherein the second space is formed between the ball seat abutment section and the fracturing ball after the release lever passes through the one-way passage mechanism.

[0021] The beneficial effect of adopting the above-mentioned further scheme is that the second space formed in the ball seat abutment section in the pusher tube is used to accommodate the fracturing ball, which makes it easier to pre-place the fracturing ball in the pusher tube.

[0022] Based on the above technical solution, the present invention can be further improved as follows.

[0023] Furthermore, an axial groove is provided on the ball seat contact section between the one-way passage mechanism and the ball seat, and a second space is formed at the axial groove to accommodate the fracturing ball. The axial groove is used to fix the one-way passage mechanism.

[0024] The beneficial effects of adopting the above-mentioned further solution are: by setting the axial groove, the space for accommodating the fracturing ball on the ball seat abutment section is increased, which facilitates the placement of the fracturing ball; at the same time, the one-way passage mechanism can be fixed at the axial groove.

[0025] The present invention also provides a ball seat assembly, including a ball seat body and an adapter, wherein the adapter is the aforementioned seat adapter, the ball seat body includes a central tube, a sealing anchoring structure and a lower connector, the sealing anchoring structure is sleeved on the central tube, the lower connector is located at the end away from the central tube and abuts against the sealing anchoring structure; the ball seat abutting section abuts against the central tube, and the ball seat connecting section is connected to the lower connector.

[0026] The beneficial effects of the ball seat assembly of the present invention are: by setting the ball seat assembly, after the fracturing ball needs to be recovered, there is no need to put in a special fracturing ball capture and recovery tool, and the fracturing ball can be recovered directly at the bottom of the well, which simplifies the process and saves costs.

[0027] Based on the above technical solution, the present invention can be further improved as follows.

[0028] Furthermore, the sealing and anchoring structure includes a sealing ring and a slip assembly. The sealing ring includes a sealing body and a pumping body, which are integrally formed. The contact surface between the sealing body and the slip assembly is a slip contact surface, which is a beveled surface used to abut against the slip assembly and press the sealing body tightly. The pumping body is a foldable skirt structure. The skirt structure has a bottom near the sealing body and is a stepped multi-level structure with gradually increasing thickness in the direction extending towards the bottom. The skirt structure has multiple openings in its circumferential direction, and these openings are evenly distributed in the circumferential direction of the skirt structure.

[0029] The beneficial effects of adopting the above-mentioned further solution are as follows: This invention sets the sealing body and the pumping body as an integrated structure. The sealing ring is directly installed on the downhole packer tool. During pumping, the skirt structure folds outward and bears force. The contact surface of the slips of the sealing body is inclined, used to abut against the slip assembly and press the sealing body tightly, ensuring that the sealing ring will not fall off, thus improving the reliability of pumping. After pumping is completed, the sealing body can be used to seal the packer tool and the wellbore. At the same time, by setting the structure to gradually thicken from top to bottom, when the pumping displacement is low, the thinner top is easy to fold outward and can quickly fold outward, generating pumping thrust and driving the entire downhole tool to descend quickly, thereby improving the pumping effect. As the pumping displacement increases, the skirt folds outward step by step, and the pumping thrust also increases step by step. In the actual pumping process, it will not cause a sudden increase in cable tension, avoiding the risk of the cable being pulled apart. In addition, the thicker structure at the bottom ensures that the skirt structure has sufficient pressure bearing capacity, achieving a reliable pumping effect. The stepped, multi-stage structure allows for better sequential opening when the pumping displacement is low.

[0030] Based on the above technical solution, the present invention can be further improved as follows.

[0031] Furthermore, the sealing body has a flange protruding towards the slip assembly at the contact point with the slip assembly, the flange being used to cover part of the slip assembly; the inner surface of the sealing body has a raised ring structure, the top end of the raised ring structure extending towards the slip assembly.

[0032] The beneficial effects of adopting the above-mentioned further solution are as follows: With the flange structure provided, after setting, part of the slip assembly provides compression and support to the flange, resulting in a good auxiliary sealing effect. Simultaneously, by providing a groove on the central tube that matches the convex ring structure, the convex ring structure is located within the groove before setting. During pumping, the convex ring structure matches and connects with the groove, preventing the pumping sealing ring from detaching from the central tube, further ensuring pumping reliability. Furthermore, during setting, the convex ring structure is pressed against the outer wall of the central tube, increasing the thickness of the sealing body and improving its sealing reliability.

[0033] Based on the above technical solution, the present invention can be further improved as follows.

[0034] Furthermore, it also includes a pressure ring, which is disposed at the bottom of the skirt; or, the pressure ring is disposed on the circumferential direction of the outer cylindrical surface between the sealing body and the pumping body.

[0035] The advantages of adopting the above-mentioned further solution are: by setting up a pressure ring structure, the pressure ring compresses the sealing ring radially against the downhole tool, further ensuring the reliability and stability of the sealing ring during pumping. Furthermore, the position of the pressure ring can be set externally or internally depending on the actual situation.

[0036] The present invention also provides a method for recovering fracturing balls, including the use of the above-mentioned setting adapter, the specific steps of which include:

[0037] Remove the release lever from the adapter;

[0038] At the section furthest from the ball seat contact point, connect the pusher to the lowest part of the oil or cable string.

[0039] The pusher is lowered into the designated position in the well.

[0040] The flowback fluid will flush the captured sphere into the first space, stopping the flowback fluid flow;

[0041] The tubing string was pulled out of the wellbore, and the captured sphere was removed.

[0042] The beneficial effect of the fracturing ball recovery method of the present invention is that when the setting adapter of the present invention is used alone as a fracturing ball recovery device, the function of efficiently catching balls can be achieved simply by releasing the release bar from the adapter.

[0043] The present invention also provides a method for recovering fracturing balls, including the use of the ball seat assembly described above, and the specific steps include:

[0044] When the ball seat assembly enters the preset position in the wellbore, the setting tool begins to work, and the ball seat completes the setting process.

[0045] The setting tool continues to work, the release lever retracts into the pusher, and a first space is formed between the ball seat connecting section and the one-way passage mechanism to accommodate the fracturing ball;

[0046] The pipe string is lifted, the setting adapter leaves the ball seat, and the fracturing ball falls out from the ball seat abutment section of the pusher and into the wellbore;

[0047] Test the wellbore condition;

[0048] When the wellbore condition is not up to standard, the flowback fluid will flush the fracturing ball into the first space and stop the flowback fluid.

[0049] Remove the setting tool and adapter from the wellbore and take out the fracturing ball.

[0050] The beneficial effect of the fracturing ball recovery method of the present invention is that after the setting is completed, the fracturing ball is sucked into the space containing the fracturing ball by directly returning the well fluid, thereby achieving the purpose of secondary pumping. Attached Figure Description

[0051] Figure 1 is a cross-sectional view of the first state of the first embodiment of the seated adapter of the present invention;

[0052] Figure 2 is a cross-sectional view of the second state of Embodiment 1;

[0053] Figure 3 is an exploded view of a single-layer structure;

[0054] Figure 4 is an exploded view of Embodiment 1 of the double-layer mechanism;

[0055] Figure 5 is an exploded view of Embodiment 2 of the double-layer mechanism;

[0056] Figure 6 is an exploded view of an embodiment of the one-way passage mechanism of the variable diameter helical spring structure.

[0057] Figure 7 is a cross-sectional view of Embodiment 1 of the ball seat assembly;

[0058] Figure 8 is a view from one direction of Embodiment 1 of the ball seat assembly;

[0059] Figure 9 is a three-dimensional structural schematic diagram of the ball seat assembly according to Embodiment 1;

[0060] Figure 10 is a cross-sectional view of the first working state of the ball seat assembly embodiment 1;

[0061] Figure 11 is a cross-sectional view of the second working state of the ball seat assembly embodiment 1;

[0062] Figure 12 is a cross-sectional view of the third working state of the ball seat assembly embodiment one;

[0063] Figure 13 is a cross-sectional view of the fourth working state of the ball seat assembly embodiment one;

[0064] Figure 14 is a cross-sectional view of the fifth working state of the ball seat assembly embodiment one;

[0065] Figure 15 is a cross-sectional view of the sealing ring in Embodiment 2 of the ball seat assembly;

[0066] Figure 16 is a cross-sectional view of the ball seat assembly in the first working state of Embodiment 2;

[0067] Figure 17 is a cross-sectional view of the second working state of the ball seat assembly embodiment 2;

[0068] Figure 18 is a cross-sectional view of the third working state of the ball seat assembly in Embodiment 2;

[0069] Figure 19 is a cross-sectional view of the sealing ring in Embodiment 3 of the ball seat assembly.

[0070] Figure 20 is a cross-sectional view of the first working state of the ball seat assembly in Embodiment 3;

[0071] Figure 21 is a cross-sectional view of the second working state of the ball seat assembly in Embodiment 3;

[0072] Figure 22 is a cross-sectional view of the third working state of the ball seat assembly according to Embodiment 3;

[0073] Figure 23 is a cross-sectional view of another embodiment of the sealing ring;

[0074] Figure 24 is a cross-sectional view of another embodiment of the sealing ring;

[0075] Figure 25 is a cross-sectional view of Embodiment 1 of the skirt structure;

[0076] Figure 26 is a cross-sectional view of Embodiment 2 of the skirt structure;

[0077] Figure 27 is a cross-sectional view of Embodiment 3 of the skirt structure.

[0078] The components represented by each number in the attached diagram are listed below: 1. Push tube, 11. Ball seat contact section, 12. First space, 13. Second space, 2. Release lever, 21. Ball seat connecting section, 3. One-way passage mechanism, 31. Spring layer, 32. Spring, 33. Retaining ring layer, 4. Fracturing ball, 5. Central tube, 6. Sealing anchoring structure, 61. Sealing ring, 611. Sealing body, 612. Pumping body, 613. Slip contact surface, 614. Flange, 615. Skirt structure, 616. Skirt bottom, 617. Pressure ring, 618. Protruding ring, 62. Slip assembly, 7. Lower connector, 8. Wellbore. Detailed Implementation

[0079] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0080] The structural schematic diagram of Embodiment 1 of the seated adapter of the present invention is shown in Figures 1 and 2.

[0081] A setting adapter includes a pusher cylinder 1 and a release lever 2. The pusher cylinder 1 has a ball seat abutment section 11 for abutting and connecting with a ball seat. The ball seat abutment section 11 is provided with a one-way passage mechanism 3 for the one-way passage of a fracturing ball 4. The passage direction of the one-way passage mechanism 3 is from the axial outer side to the inner side of the ball seat abutment section 11. In this embodiment, the pusher cylinder 1 is configured as a two-section structure, that is, the ball seat abutment section 11 is set separately, and can be ultimately configured into pusher cylinders of different lengths.

[0082] The drop lever 2 has a ball seat connecting section 21, which passes through a one-way passage mechanism 3 for fitting and connecting with the ball seat. After the ball seat is set, the drop lever 2 retracts into the push cylinder 1. There is a first space 12 between the end of the drop lever 2, the ball seat abutment section 11, and the one-way passage mechanism 3 to accommodate the fracturing ball 4. In this embodiment, the drop lever 2 is also configured as a two-section structure. Since the overall length of the drop lever 2 is relatively long, the two-section structure shortens the length of a single lever, making it easier to manufacture; at the same time, the two-section design allows for adjustment of the overall length.

[0083] In this embodiment, as shown in FIG1, the one-way passage mechanism 3 is located in the middle of the ball seat abutment section 11. The release lever 2 retracts into the push tube 1. A first space 12 that can accommodate the fracturing ball 4 is formed in the area of ​​the ball seat abutment section 11 on the left side of the one-way passage mechanism 3 and the end of the release lever 2.

[0084] As shown in Figure 2, after the drop bar 2 passes through the one-way passage mechanism 3, there is a second space 13 between the ball seat contact section 11 and the one-way passage mechanism 3 to accommodate the fracturing ball 4.

[0085] As shown in Figure 7, on the right side of the one-way passage mechanism 3, at the groove structure of the ball seat abutment section 11, the groove structure is the notch structure in the figure. Because the groove structure penetrates the inner and outer surfaces of the ball seat connecting section 21, the space here becomes larger, with enough space to accommodate the fracturing ball 4. It should be noted that the circumferential width of the groove structure is smaller than the diameter of the fracturing ball, ensuring that the fracturing ball will not fall out radially from the ball seat connecting section 21.

[0086] As shown in Figures 3, 4, 5, and 6, the groove structure can also be used to install the one-way passage mechanism 3. As shown in Figure 3, the upward-protruding part of the spring sheet layer 31 is directly installed in the groove structure; as shown in Figures 4 and 5, the upward-protruding parts of the spring sheet layer 31 and the retaining ring layer 33 are installed in the groove structure; as shown in Figure 6, the upward-protruding part of the one-way passage mechanism 3 is installed in the groove structure.

[0087] In this embodiment of the setting adapter, after setting is completed, the release lever 2 retracts into the push cylinder 1. The end of the release lever 2, the ball seat abutment section 11, and the one-way passage mechanism 3 have a first space 12 for accommodating the fracturing ball 4. When a secondary pumping operation is required, the fracturing ball 4 is pushed back into the first space 12 in the push cylinder 1 by a backflow method. At the same time, the one-way passage mechanism 3 restricts the fracturing ball 4 from falling out of the push cylinder 1, ensuring the reliability of the fracturing ball 4 recovery.

[0088] Referring to Figure 3, which illustrates a structural embodiment of the one-way passage mechanism 3, the one-way passage mechanism 3 is a single-layer mechanism consisting of a spring sheet layer 31. The spring sheet layer 31 has multiple spring sheets 32, the diameter of which is smaller than the diameter of the fracturing ball 4. The ends of the multiple spring sheets 32 extend obliquely away from the ball seat abutment section 11. In this embodiment, the spring sheet layer 31 is configured as a circular thin sheet structure. Three protruding components are provided at the edge of the thin sheet for fixed connection with the ball seat abutment section 11. Eight spring sheets 32 are evenly distributed in the middle of the thin sheet, the diameter of which is smaller than the diameter of the fracturing ball 4. Three groove structures are provided axially in the ball seat abutment section 11, with the bottom of the groove structures located in the middle of the ball seat abutment section. The protruding components of the spring sheet layer 31 are located at the bottom of the three groove structures and are fixedly connected. It should be noted that the number of spring sheets 32 can be selected according to actual working conditions, such as 3-10.

[0089] When the fracturing ball 4 needs to be recovered, the well fluid is returned, and the fracturing ball 4 is pushed by the well fluid to the right end of the one-way mechanism of the adapter. The fracturing ball 4 squeezes the end of the spring sheet 32 ​​of the spring sheet layer 31. Since the entire spring sheet 32 ​​is in an unconstrained state and the end of the spring sheet 32 ​​is tilted inward, the entire spring sheet 32 ​​is easily deformed, and the aperture becomes larger. The fracturing ball 4 then passes through the spring sheet layer 31 and enters the first space 12. When the fracturing ball 4 enters the first space 12, the spring strip 32 recovers its deformation, so that the aperture formed by the ends of the eight spring strips 32 is smaller than the diameter of the fracturing ball 4. In subsequent operations, if the fracturing ball 4 in the first space 12 is subjected to pressure to squeeze the spring strip layer 31, the ends of the spring strips 32 in the spring strip layer 31 are still tilted inward. It is difficult for the fracturing ball 4 to squeeze the spring strips 32 to become perpendicular to the axis of the ball seat contact section 11. The aperture formed by the ends of the spring strips 32 cannot be smaller than the diameter of the fracturing ball 4. Therefore, the fracturing ball 4 cannot pass through the spring strip layer 31, ensuring that the fracturing ball 4 will not fall out of the first space 12, which has high reliability.

[0090] The schematic diagram of the second embodiment of the one-way passage mechanism 3 is shown in Figure 4. The one-way passage mechanism 3 is a double-layer mechanism, including a spring sheet layer 31 and a retaining ring layer 33. The spring sheet layer 31 has multiple spring sheets 32. The diameter of the holes formed at the ends of the multiple spring sheets 32 is smaller than the diameter of the fracturing ball 4. The spring sheet layer 31 is located on the axial inner side of the ball seat abutment section 11. The retaining ring layer 33 has a through hole through which the fracturing ball 4 passes. The retaining ring layer 33 is located on the axial outer side of the ball seat abutment section 11.

[0091] In this embodiment, the spring sheet layer 31 is configured as a circular thin sheet structure. Three protruding components are provided at the edge of the thin sheet for fixed connection with the ball seat abutment section 11. Eight spring sheets 32 are evenly distributed in the middle of the thin sheet, and the aperture formed at the ends of the eight spring sheets 32 is smaller than the diameter of the fracturing ball 4. Three groove structures are provided axially in the ball seat abutment section 11, with the bottom of the groove structures located in the middle of the ball seat abutment section. The protruding components of the spring sheet layer 31 are located at the bottom of the three groove structures and are fixedly connected. The retaining ring layer 33 is also configured as a thin sheet structure. Compared with the spring sheet layer 31, it does not have spring sheets 32. The retaining ring layer 33 has a through hole in the middle, with a diameter slightly larger than the diameter of the fracturing ball 4, for the fracturing ball 4 to pass through. The diameter of its through hole is larger than the aperture formed at the ends of the eight spring sheets 32. The retaining ring layer 33 and the spring sheet layer 31 are stacked and fixed at the groove structures. In this embodiment, the spring sheets 32 are perpendicular to the axis of the ball seat abutment section 11.

[0092] In this embodiment, the setting adapter of this embodiment is used for downhole setting. After setting is completed, the release rod 2 retracts into the pusher barrel 1. There is a first space 12 between the end of the release rod 2, the ball seat abutment section 11, and the one-way passage mechanism 3 to accommodate the fracturing ball 4. When it is necessary to perform fracturing ball 4 retrieval, the fracturing ball 4 is pushed back into the first space 12 in the pusher barrel 1 by backflow. At the same time, the one-way passage mechanism 3 restricts the fracturing ball 4 from falling out of the pusher barrel 1, ensuring the reliability of fracturing ball 4 retrieval. Specifically, during backflow, the fracturing ball 4 is pushed by the well fluid towards the ball seat abutment section of the adapter. Since the aperture of the retaining ring layer 33 is larger than the diameter of the fracturing ball 4, the fracturing ball 4 can pass through the retaining ring layer 33 and squeeze the end of the spring plate 32 of the spring plate layer 31. Since the entire spring plate 32 is in an unconstrained state, the entire spring plate 32 deforms, thereby increasing the aperture, and the fracturing ball 4 passes through the spring plate layer 31 and enters the first space 12. When the fracturing ball 4 enters the first space 12, the spring strips 32 recover their deformation, so that the aperture formed at the ends of the eight spring strips 32 is smaller than the diameter of the fracturing ball 4. In subsequent operations, if the fracturing ball 4 in the first space 12 is subjected to pressure to squeeze the spring strip layer 31, only the ends of the spring strips 32 in the spring strip layer 31 are in a free state, while the other parts are constrained by the retaining ring layer 33 and cannot be deformed. Therefore, the fracturing ball 4 cannot pass through the spring strip layer 31, ensuring that the fracturing ball 4 will not fall out of the first space 12, which has high reliability.

[0093] The schematic diagram of the unidirectional passage mechanism 3 in Embodiment 3 is shown in Figure 5. It is also configured as a double-layer structure. The difference from the embodiment is that the ends of the multiple spring pieces 32 extend obliquely away from the ball seat abutment section 11, that is, the free ends of the spring pieces 32 extend inward. Because the entire spring piece 32 is in an unconstrained state and its ends are obliquely inclined inward, the entire spring piece 32 is easily deformed, resulting in a larger aperture. The fracturing ball 4 can then easily pass through the spring piece layer 31 and enter the first space 12. Similarly, due to the combined action of the oblique spring piece 32 and the retaining ring layer 33, the fracturing ball 4 cannot fall out of the first space 12.

[0094] Figure 6 shows another embodiment of the one-way passage mechanism 3. In this embodiment, the one-way passage mechanism 3 is a variable-diameter helical spring structure, with the small end of the variable-diameter helical spring extending obliquely away from the ball seat contact section. In this embodiment, the adapter has a central through-hole smaller than the fracturing ball. During fracturing ball retrieval, the fracturing ball enters the variable-diameter helical spring structure from the right end. When the impact force of the backflow flow on the fracturing ball is large, the diameter of the central through-hole increases, allowing the fracturing ball to smoothly pass through the variable-diameter helical spring structure and enter the first space. Due to the variable-diameter helical spring structure, the fracturing ball will not fall out of the first space, i.e., it will not fall out from the left end.

[0095] An embodiment of the ball seat assembly of the present invention is shown in Figures 7 to 9. It includes a ball seat body and an adapter, the adapter being the aforementioned setting adapter. The ball seat body includes a central tube 5, a sealing anchoring structure 6, and a lower connector 7. The sealing anchoring structure 6 is sleeved on the central tube 5, and the lower connector 7 is located at the end away from the central tube 5 and abuts against the sealing anchoring structure 6. The ball seat abutting section 11 abuts against the central tube 5, and the ball seat connecting section 21 is connected to the lower connector 7. In this embodiment, the second space 13 is provided with a fracturing ball 4.

[0096] In this embodiment, the sealing anchoring structure 6 includes a sealing ring 61 and a slip assembly 62. The slip assembly 62 is a segmented slip, and then the slip assembly 62 is integrated into a single structure through a spiral structure at the end that abuts against the sealing ring 61.

[0097] The working process of the ball seat assembly in this embodiment is shown in Figures 10 to 14. As shown in Figure 10, the ball seat body is pumped to a designated position in the wellbore 8 and set using a setting tool. After setting, the adapter is removed from the ball seat by lifting the tubing string. At this time, as shown in Figure 11, the fracturing ball 4 falls from the second space 13 into the wellbore 8. As shown in Figure 12, during ball seat verification or fracturing, the fracturing ball 4 falls into the sealing position of the central tube 5. In the event of a perforation failure, the fracturing ball 4 capture scheme needs to be activated, as shown in Figures 13 and 14. At this time, the fracturing ball 4 is pushed back into the first space 12 inside the pusher tube 1 by a backflow method. The fracturing ball 4 is retrieved downhole, the adapter is lifted out of the wellbore 8, and the fracturing ball 4 is taken out. After the fracturing ball 4 is taken out, other subsequent operations are performed.

[0098] The second embodiment of the ball seat assembly of the present invention is shown in Figures 15 to 18. The difference from the first embodiment is that the sealing ring 61 includes a sealing body 611 and a pumping body 612, which are integral structures. The contact surface between the sealing body 611 and the slip assembly 62 is a slip contact surface 613, which is a beveled surface used to abut against the slip assembly 62 and press the sealing body 611 tightly. The pumping body 612 is a foldable skirt structure 615. The skirt structure 615 has a skirt bottom 616 near the sealing body 611, and the skirt structure 615 has a stepped multi-level structure with gradually increasing thickness in the direction extending towards the skirt bottom 616.

[0099] The sealing ring 61 includes a sealing body 611 and a pumping body 612, as shown in Figure 15. The sealing body 611 is on the right, and the pumping body 612 is on the left. The sealing body 611 and the pumping body 612 are integrally formed to form the sealing ring 61. The contact surface between the sealing body 611 and the slip assembly 62 is the slip contact surface 613. The slip contact surface 613 is a bevel, used to abut against the slip assembly 62 and press the sealing body 611 tightly. The sealing body 611 has a flange 614 protruding towards the slip assembly 62 at the contact point with the slip assembly 62. The pumping body 612 has an outwardly foldable skirt structure 615. Because the sealing ring 61 has both sealing and pumping functions, it is generally made of rubber or a highly ductile and highly tough plastic material.

[0100] The skirt structure 615 has a bottom 616 near the sealing body 611, and its thickness gradually increases towards the bottom 616. The outer wall of the skirt structure 615 and the outer wall of the sealing body 611 are coplanar, forming a sealing ring 61. In this embodiment, the inner diameter of the sealing ring 61 is a tapered hole structure, with the small end of the tapered hole structure located at the end of the sealing body 611. In this embodiment, a pressure ring 617 is provided on the sealing body 611 near the bottom 616 of the skirt, and a flange 614 is provided on the sealing body 611.

[0101] The inner surface of the sealing body 611 is provided with a convex ring 618 structure. The top end of the convex ring 618 structure extends towards the slip contact surface 613 of the sealing body 611, i.e., the right end as shown in the figure. By setting the convex ring 618 structure, the convex ring 618 structure matches and connects with the groove of the central tube 5. During pumping, the sealing ring 61 will not fall off the central tube 5, further ensuring the reliability of pumping. At the same time, during setting, the convex ring 618 structure is pressed tightly against the outer wall of the central tube 5, increasing the thickness of the sealing body 611 and improving the sealing reliability of the sealing body 611.

[0102] The recovery process of the fracturing ball 4 in the ball seat assembly in this embodiment is the same as that in Embodiment 1, and will not be repeated here. The sealing and pumping functions of the ball seat assembly sealing ring 61 will be described below. The first working state of the pumping process of the ball seat assembly in Embodiment 2 is shown in Figure 16, which is the state before pumping when the ball seat assembly is just placed into the wellbore 8. The ball seat assembly is located in the middle of the wellbore 8. Since it is not in the pumping state, the skirt structure 615 of the pumping body 612 in the sealing ring 61 is in the normal state and does not turn outward.

[0103] The second working state of the pumping process in this embodiment is shown in Figure 17, which is the state in which the ball seat assembly is in the wellbore 8 and is being pumped. On the left side of Figure 17, pumping fluid is input, flowing from left to right. Due to the pressure of the pumping fluid, the skirt structure 615 of the pumping body 612 flips outward, and the pumping fluid generates thrust on the entire ball seat assembly, pushing it forward. During the pumping process of the ball seat assembly, the pressure ring 617 maintains a pressing effect on the pumping body 612, that is, the pressure ring 617 continuously presses the pumping body 612 tightly against the central pipe 5. The sealing ring 61 will not be washed away by the pumping pressure, ensuring reliability.

[0104] The third working state of the pumping process in this embodiment is shown in Figure 18, which is the state where the ball seat assembly is in the wellbore 8 after pumping is completed and set. After setting, the slip teeth in the slip assembly 62 are anchored to the inner wall of the wellbore 8, and the sealing body 611 in the sealing ring 61 abuts and seals against the inner wall of the wellbore 8. In this embodiment, after setting, part of the slip assembly 62 provides a pressing and supporting function for the flange 614, and the flange 614 provides a good auxiliary sealing function.

[0105] The third embodiment of the ball seat assembly of the present invention is shown in Figures 19 to 22. Compared with the second embodiment, the difference is that, as shown in Figure 18, the cross-section of the pressure ring 617 in this embodiment is circular, and it abuts against the skirt structure 615 at the bottom 616 of the skirt. This structure further ensures the reliability and stability of the sealing ring 61 during the pumping process. That is, during the pumping process, the pressure ring 617 always maintains a pressing effect on the pump body 612, and the entire sealing ring 61 will not be washed away by the pumping pressure. At the same time, after the setting is completed, the pressure ring 617 will provide support for the skirt structure 615, thereby making the skirt structure 615 abut against the inner wall of the wellbore 8 and achieving auxiliary sealing.

[0106] The pumping process of the ball seat assembly in this embodiment is shown in Figures 20 and 21. The state change of the sealing ring 61 during the operation is consistent with that in embodiment two. The third operating state of the pumping process in this embodiment is shown in Figure 22. After setting, the slip teeth in the slip assembly 62 are anchored to the inner wall of the wellbore 8, and the sealing body 611 in the sealing ring 61 abuts and seals against the inner wall of the wellbore 8. In this embodiment, after setting, the pressure ring 617 provides support for the skirt structure 615, thereby causing the skirt structure 615 to abut against the inner wall of the wellbore 8 and achieving auxiliary sealing.

[0107] A cross-sectional view of another embodiment of the sealing ring 61 is shown in FIG23. In this embodiment, the difference from the sealing ring 61 in the second embodiment of the ball seat assembly is that the inner surface of the sealing body 611 does not have a convex ring 618 structure, which is simpler.

[0108] A cross-sectional view of another embodiment of the sealing ring 61 is shown in Figure 24. In this embodiment, compared with the sealing ring 61 in embodiment three of the ball seat assembly, the difference is that the contact surface 613 of the slip is a vertical surface, and the bottom 616 of the skirt is not provided with a groove structure; the skirt structure 615 has multiple openings in the circumferential direction. At the same time, a pressure ring 617 is provided on the outer cylindrical surface between the sealing body 611 and the pumping body 612. Specifically, the outer circular surface of the pressure ring 617 is not higher than the surface of the sealing body 611.

[0109] Regarding the skirt structure 615 of the sealing ring 61, the present invention provides the following three embodiments for illustration.

[0110] The cross-sectional view of the skirt structure 615 in Embodiment 1 is shown in Figure 25. The skirt is set with a structure of multiple tapers. That is, the taper is smaller and the skirt is thinner at the top of the skirt; the taper is larger and the skirt is thicker near the bottom of the skirt 616, forming a structure in which the thickness gradually increases from the edge of the skirt to the bottom of the skirt 616.

[0111] The cross-sectional view of the skirt structure 615 in Embodiment 2 is shown in Figure 26. Compared with Figure 25, all the tapers in the skirt structure 615 are the same, except that steps are provided between adjacent tapers, forming a stepped multi-level structure. This design provides better step-by-step opening effect when the pumping displacement is low.

[0112] The sectional view of the skirt structure 615 in Embodiment 3 is shown in Figure 27. Compared with Figure 26, there is no tapered structure, and each step is a cylindrical structure.

[0113] This embodiment also provides two methods for recovering fracturing balls. One method for recovering fracturing balls includes using the aforementioned setting adapter, and the specific steps include:

[0114] Remove the handle from the adapter.

[0115] At the section away from the ball seat, connect the pusher to the bottom of the string of oil or cable.

[0116] The pusher is lowered to the designated position in the well.

[0117] The return fluid flushes the captured sphere into the first space.

[0118] The tubing string is pulled out of the wellbore, and the captured fracturing balls are removed, stopping the flowback of well fluid. This fracturing ball recovery method is applicable to any operating condition requiring ball recovery; simply install the setting adapter, and it is highly efficient and reliable.

[0119] Another method for recovering fracturing balls includes using the aforementioned ball seat assembly, with specific steps including:

[0120] The ball seat assembly of the setting tool is inserted into the preset position in the wellbore and the setting is completed.

[0121] The setting tool and the setting adapter are removed from the ball seat.

[0122] The setting tool continues to work, retracting the release handle into the pusher, and has a first space for accommodating the fracturing ball between the ball seat connection section and the one-way passage mechanism.

[0123] The fracturing ball falls out of the ball seat contact section of the pusher and into the wellbore.

[0124] Test the wellbore condition.

[0125] When the wellbore condition is unqualified, the flowback fluid will flush the fracturing ball into the first space and stop the flowback fluid.

[0126] Remove the setting tool and adapter from the wellbore and take out the fracturing ball.

[0127] Specifically, this embodiment describes in detail the method of the present invention by listing the working process of perforation operation in the well.

[0128] Downhole perforation is an important operation in the oil drilling and completion process. It aims to open the oil layer with a perforating gun so that fluids in the formation can flow into the wellbore for oil and gas production.

[0129] Assemble the perforating gun string, the setting tool, and the ball seat assembly in this embodiment. Pump the ball seat assembly to the predetermined position, and the setting tool begins its work, completing the setting process.

[0130] The setting tool continues to move until it has completed its entire stroke; at this point, due to the movement of the pusher cylinder of the adapter carried by the setting tool, the release lever retracts into the pusher cylinder, forming the first space for the fracturing ball to be accommodated.

[0131] The tubing string is lifted, and the fracturing ball falls into the wellbore from the first space of the pusher.

[0132] Continue lifting the pipe string to the perforation section to complete the perforation operation.

[0133] If the perforation operation is normal, pull the tubing string up to the wellhead and remove it.

[0134] Then the pump is turned on, the fracturing ball is placed on the ball seat, and fracturing begins.

[0135] If perforation failure is detected, the fracturing ball recovery program needs to be initiated.

[0136] The backflow process begins by opening the valve at the wellhead. The high-pressure fluid at the bottom of the well will flow from the bottom to the wellhead. At this time, the fluid will carry the fracturing ball towards the wellhead, thus pushing the fracturing ball into the pusher of the adapter.

[0137] Close the wellhead valve, pull the tubing to the wellhead, and remove the adapter and fracturing ball.

[0138] Replace the perforating gun string and reinsert it into the well.

[0139] The pump pipe is connected to the location where perforation is needed to complete the perforation operation.

[0140] Raise the tubing string to the wellhead and remove it.

[0141] The fracturing balls are re-inserted, pumped, and then seated on the ball seat.

[0142] Fracturing completed.

[0143] The above specific embodiments are merely examples to facilitate understanding of the technical solution of the present invention.

[0144] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A seat adapter, characterized in that it includes a pusher and a release lever; The pusher has a ball seat abutment section, which is used to abut and connect with a ball seat. The ball seat abutment section is provided with a one-way passage mechanism for the fracturing ball to pass through in one direction. The passage direction of the one-way passage mechanism is the direction extending from the outer side of the axial direction of the ball seat abutment section to its inner side. The drop stick has a ball seat connecting section, which passes through the one-way passage mechanism for fitting and connecting with the ball seat. After the ball seat is set, the drop stick retracts into the push tube. There is a first space between the end of the drop stick, the ball seat abutment section and the one-way passage mechanism to accommodate the fracturing ball.

2. The seat adapter according to claim 1, characterized in that, The unidirectional passage mechanism is a single-layer mechanism, which is a spring sheet layer. The spring sheet layer has multiple spring sheets, and the aperture formed at the ends of the multiple spring sheets is smaller than the diameter of the fracturing ball. The ends of the multiple spring sheets extend obliquely away from the ball seat abutment section.

3. A sealing adapter according to claim 2, characterized in that, The spring has a first end and a second end. The first end is connected to the outer ring to form an integral structure. The outer ring is fixedly disposed on the ball seat abutment section. The second end extends obliquely away from the ball seat abutment section.

4. A sealing adapter according to claim 1, characterized in that, The unidirectional passage mechanism is a double-layer mechanism, including a spring sheet layer and a retaining ring layer. The spring sheet layer has multiple spring sheets, and the diameter of the holes formed at the ends of the multiple spring sheets is smaller than the diameter of the fracturing ball. The spring sheet layer is located on the axial inner side of the ball seat abutment section. The retaining ring layer has a through hole for the fracturing ball to pass through, and the diameter of the through hole is larger than the diameter of the fracturing ball. The retaining ring layer is located on the axial outer side of the ball seat abutment section.

5. A sealing adapter according to claim 1, characterized in that, The one-way passage mechanism is a variable diameter helical spring structure. The diameter of the middle hole of the variable diameter helical spring structure is smaller than the diameter of the fracturing ball. The small end of the variable diameter helical spring extends obliquely away from the ball seat abutment section.

6. A seat adapter according to any one of claims 1 to 5, characterized in that, It also includes a second space for accommodating the fracturing ball, and the second space is formed between the ball seat abutment section and the fracturing ball after the release bar passes through the one-way passage mechanism.

7. A sealing adapter according to claim 6, characterized in that, An axial groove is provided on the ball seat contact section between the one-way passage mechanism and the ball seat. The axial groove forms a second space to accommodate the fracturing ball and is used to fix the one-way passage mechanism.

8. A ball seat assembly, comprising a ball seat body and an adapter, characterized in that, The adapter is a seated adapter as described in any one of claims 1 to 7. The ball seat body includes a central tube, a sealing anchor structure, and a lower connector. The sealing anchor structure is sleeved on the central tube. The lower connector is located at the end away from the central tube and abuts against the sealing anchor structure. The ball seat abutting section abuts against the central tube, and the ball seat connecting section is connected to the lower connector.

9. A ball seat assembly according to claim 8, characterized in that, The sealing and anchoring structure includes a sealing ring and a slip assembly. The sealing ring includes a sealing body and a pumping body, which are integrally formed. The contact surface between the sealing body and the slip assembly is a slip contact surface, which is a beveled surface used to abut against the slip assembly and press the sealing body tightly. The pumping body is a foldable skirt structure. The skirt structure has a bottom near the sealing body and is a stepped multi-level structure with gradually increasing thickness in the direction extending towards the bottom. The skirt structure has multiple openings in its circumferential direction, and these openings are evenly distributed in the circumferential direction of the skirt structure.

10. A ball seat assembly according to claim 9, characterized in that, The sealing body has a flange protruding towards the slip assembly at the contact point with the slip assembly, and the flange is used to cover part of the slip assembly; the inner surface of the sealing body has a raised ring structure, and the top end of the raised ring structure extends towards the slip assembly.

11. A ball seat assembly according to claim 10, characterized in that, It also includes a pressure ring, which is disposed at the bottom of the skirt; or, the pressure ring is disposed circumferentially on the outer cylindrical surface between the sealing body and the pumping body.

12. A method for recovering fracturing balls, characterized in that, Including the use of the seat adapter as described in any one of claims 1 to 7, the specific steps include: Remove the release lever from the adapter; At the section furthest from the ball seat contact point, connect the pusher to the lowest part of the oil or cable string. The pusher is lowered into the designated position in the well. The flowback fluid will flush the captured sphere into the first space, stopping the flowback fluid flow; The tubing string was pulled out of the wellbore, and the captured sphere was removed.

13. A method for recovering fracturing balls, characterized in that, Including the use of the ball seat assembly according to any one of claims 8 to 11, the specific steps include: When the ball seat assembly enters the preset position in the wellbore, the setting tool begins to work, and the ball seat completes the setting process. The setting tool continues to work, the release lever retracts into the pusher, and a first space is formed between the ball seat connecting section and the one-way passage mechanism to accommodate the fracturing ball; The pipe string is lifted, the setting adapter leaves the ball seat, and the fracturing ball falls out from the ball seat abutment section of the pusher and into the wellbore; Test the wellbore condition; When the wellbore condition is not up to standard, the flowback fluid will flush the fracturing ball into the first space and stop the flowback fluid. Remove the setting tool and adapter from the wellbore and take out the fracturing ball.

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