Full-bore infinite fracturing sliding sleeve for horizontal well

Abstract

The invention relates to the technical field of oil field oil production engineering, in particular to a full-bore infinite fracturing sliding sleeve for a horizontal well, which comprises a switching mechanism and a plurality of actuating mechanisms, and the plurality of actuating mechanisms jointly form a channel for flowing of fracturing fluid; the actuating mechanism comprises an upper joint and a lower joint; the lower connector is provided with a first gap, and the first gap communicates with the channel. An inner cylinder is arranged on the inner side of the lower joint; a gap II is formed in the inner cylinder; under the action of the switching mechanism, the inner cylinder can slide in the axial direction and has a first position and a second position correspondingly before and after sliding, and when the inner cylinder is located at the first position, the second gap and the first gap are staggered in the axial direction; when the first opening and the second opening are located at the second position, the first opening and the second opening correspond to each other and communicate with each other, the inner barrel and the lower connector are in stop fit, well sections of the horizontal well are fractured conveniently, and after fracturing is completed, the switching mechanism can be automatically matched with different executing mechanisms through the special structures of the switching mechanism and the executing mechanisms; and the same well section of the horizontal well can be fractured for multiple times.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield production engineering, in particular to a full-bore unlimited-stage fracturing sliding sleeve for horizontal wells. BACKGROUND

[0002] In oilfield production operations, staged fracturing technology is one of the core technologies for promoting the efficient development of low-permeability oil and gas reservoirs. The core operation logic is to divide the production area into multiple independent operation sections according to the geological characteristics and reservoir distribution of the target well section or rock formation. By carrying out fracturing operation on each independent section one by one, the original closed state of the reservoir is broken, and more abundant oil and gas seepage channels are constructed, thereby realizing the increase of single well production and oil and gas recovery.

[0003] In the fracturing implementation process of each operation section, two types of technical solutions are mainly used, namely, drag-type fracturing process and full-bore unlimited-stage fracturing process. Among them, the full-bore unlimited-stage fracturing process has outstanding advantages in operation flexibility, wellbore utilization rate and scene adaptability, and has been widely used in various oilfield production scenes.

[0004] The application range of the full-bore unlimited-stage fracturing process covers both open-hole completion and casing completion. Compared with the traditional ball sliding sleeve + packer staged fracturing process, the core difference between the two lies in the opening mode of the sliding sleeve.

[0005] In related technologies, for example, Chinese patent CN107178352B discloses a downhole full-bore unlimited-stage fracturing sliding sleeve. The opening of the sliding sleeve is realized by axial movement, which is more stable than the circumferential rotation mode. By changing the axial distance of the push block to correspond to different inner cylinders, it is realized that each specific actuator can only correspond to a specific switching mechanism, achieving accurate identification effect.

[0006] However, the above-mentioned downhole full-bore unlimited-stage fracturing sliding sleeve can only perform fracturing on the same well section once in actual use, and has poor adaptability. Moreover, a switching mechanism can only adapt to one actuator at a time, and when the switching mechanism needs to be changed, the switching mechanism needs to be removed and then the axial distance of the push block needs to be changed. Not only is the procedure complicated, but also the construction time is long, which affects the construction efficiency. SUMMARY

[0007] Therefore, it is necessary to provide a full-bore unlimited-stage fracturing sliding sleeve for horizontal wells to solve the problems that the current full-bore unlimited-stage fracturing sliding sleeve can only perform fracturing on the same well section once, resulting in poor adaptability and complex switching mechanism changing operation.

[0008] The above-mentioned purpose is realized by the following technical solutions: The full-bore unlimited-stage fracturing sliding sleeve for horizontal wells comprises a switching mechanism and a plurality of executing mechanisms; The executing mechanism comprises an upper joint and a lower joint, and an inner cylinder is arranged on the inner side of the lower joint. The switching mechanism can rotate and comprises a sliding seat which is located on the inner side of the inner cylinder and can slide along the axial direction.

[0009] Further, the iris assembly comprises a plurality of blocking blocks which are arranged along the circumferential direction and can be movably sleeved on the sliding seat and can be attached to the inner circumferential wall of the inner cylinder.

[0010] Further, the side wall of each blocking block is provided with an elastic layer one.

[0011] Further, the attachment position of the inner cylinder and the blocking block is provided with an annular elastic layer two.

[0012] Further, the blocking block is made of an elastic material.

[0013] Further, the elastic material is rubber.

[0014] Further, the end head is internally provided with a cavity one, the cavity one is internally provided with a baffle one and a baffle two, the baffle one is fixedly connected with the end head, the baffle two is connected with the sliding base, and the baffle one and the baffle two divide the cavity one into two sub-cavities which are not communicated with each other, and one of the sub-cavities is configured to be capable of receiving liquid from the outside.

[0015] Further, the baffle one and the baffle two are connected with a first elastic member, after the end head is rotated relative to the sliding base, under the action of the first elastic member, the end head has a tendency to rotate to reset.

[0016] Further, the upper joint and the lower joint of the same execution mechanism are threadedly connected; and the lower joint and the upper joint of adjacent execution mechanisms are threadedly connected.

[0017] Further, the upper joint and the lower joint of the same execution mechanism and the lower joint and the upper joint of adjacent execution mechanisms are fixedly connected through fasteners.

[0018] The beneficial effects of the present application are: The present application relates to a full-bore unlimited-stage fracturing sliding sleeve for horizontal wells, a switching mechanism and a plurality of execution mechanisms are arranged, and the plurality of execution mechanisms jointly constitute a channel for conveying fracturing fluid; during fracturing, the inner cylinder is driven to move from the first position to the second position under the action of the switching mechanism, at this time, the fracture one, the fracture two and the channel are communicated, then the fracturing fluid is conveyed into the channel, and the fracturing fluid is sprayed out in turn after passing through the fracture two and the fracture one, so that the horizontal well section is fractured; after fracturing is completed, the inner cylinder is driven to move from the second position to the first position by using the special structure of the switching mechanism and the execution mechanism, so that the fracture two and the fracture one are axially dislocated, then the fracturing process is repeated, so that multiple fracturing of the same well section is realized, and the applicability is improved; at the same time, the switching mechanism can be adapted to different execution mechanisms, the operation steps are simplified, the construction time is reduced, and the construction efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The cross-sectional structure schematic of the full-bore unlimited-stage fracturing sliding sleeve for horizontal wells provided by the embodiment of the present application Figure 1 Figure 2 The partial enlarged structure schematic of the W in the middle Figure 1 Figure 3 The top view structure schematic of the full-bore unlimited-stage fracturing sliding sleeve for horizontal wells provided by the embodiment of the present application Figure 4 The cross-sectional view of the A-A in the middle Figure 3 The partial enlarged structure schematic of the X in the middle Figure 5 Figure 4 The partial enlarged structure schematic of the X in the middle Figure 6 The partial enlarged structure schematic of the X in the middle Figure 3 ​​​Cross-sectional view of B-B direction; Figure 7 As Figure 6 Local enlarged structure schematic view at Y; Figure 8 Front view structural schematic view of full bore unlimited stage fracturing sliding sleeve for horizontal well provided by the embodiment of the present application; Figure 9 As Figure 8 Cross-sectional view of C-C direction; Figure 10 Cross-sectional structural schematic view of full bore unlimited stage fracturing sliding sleeve for horizontal well provided by the embodiment of the present application Figure 2 ; Figure 11 Cross-sectional structural schematic view of full bore unlimited stage fracturing sliding sleeve for horizontal well provided by the embodiment of the present application Figure 3 ; Figure 12 As Figure 11 Local enlarged structure schematic view at Z; Figure 13 Cross-sectional structural schematic view of full bore unlimited stage fracturing sliding sleeve for horizontal well provided by the embodiment of the present application Figure 4 ; Figure 14 Stereoscopic cross-sectional structural schematic view of inner cylinder of full bore unlimited stage fracturing sliding sleeve for horizontal well provided by the embodiment of the present application; Figure 15 Stereoscopic structural schematic view of latch of full bore unlimited stage fracturing sliding sleeve for horizontal well provided by the embodiment of the present application; Figure 16 Stereoscopic structural schematic view of switch mechanism of full bore unlimited stage fracturing sliding sleeve for horizontal well provided by the embodiment of the present application.

[0020] Wherein: 1. Upper connector; 2. Lower connector; 201. Crack 1; 202. Slot; 203. Angled structure 2; 204. Narrowing structure; 3. Inner cylinder; 301. Crack 2; 302. Guide protrusion 2; 3021. Curved surface structure 1; 303. Cavity 2; 304. Conical annular surface structure 1; 305. Mounting groove; 4. Pin; 401. Slip ring; 402. Angled surface structure 1; 403. Angled surface structure 3; 5. First compression spring; 6. Slide seat; 601. Guide protrusion 1; 6011. Curved surface structure 2; 602. Slide groove 1; 603. Stop protrusion; 604. Baffle 2 605. Cavity 3; 606. Connecting rod; 607. Column protrusion; 608. Conical annular structure 2; 609. Infusion channel; 610. Telescopic groove; 7. Locking block; 701. Inclined structure 4; 8. Second compression spring; 9. End; 901. Key block; 9011. Inclined structure 5; 9012. Protrusion; 902. Cavity 1; 903. Baffle 1; 904. Fixing sleeve; 905. Conical annular structure 3; 10. Spring; 11. Iris assembly; 1101. Sealing block; 11011. Slide groove 2; 1102. Third compression spring; 12. Torsion spring. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0022] The component designations used in this document, such as "first" and "second," are merely for distinguishing the described objects and do not have any sequential or technical meaning. The terms "connection" and "linkage," unless otherwise specified, include both direct and indirect connections (linkages). In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0024] Existing full-bore unlimited-stage fracturing sleeves only support single fracturing operations on the same section of a horizontal well. They cannot be adjusted for secondary or multiple fracturing operations based on reservoir dynamics or production needs, resulting in poor technical adaptability. Furthermore, existing full-bore unlimited-stage fracturing sleeves employ a "one-to-one" fixed adaptation mode, meaning one switching mechanism can only be adapted to one specific actuator. When production requirements change and the actuator type adapted to the switching mechanism needs to be changed, the entire downhole switching mechanism must be removed, the axial spacing of the push blocks adjusted on the surface, and then it must be re-installed and tested downhole. This adjustment process is not only cumbersome and time-consuming, but more importantly, the complex downhole environment and frequent tubing string tripping operations increase the risk of wellbore collapse and contamination, while also significantly extending the construction cycle and reducing overall production efficiency.

[0025] Based on this, embodiments of the present invention provide a full-bore, unlimited-stage fracturing sleeve for horizontal wells, which is particularly suitable for oilfield exploitation operations.

[0026] Specifically, such as Figures 1 to 16 As shown, the horizontal well's full-bore, unlimited-stage fracturing sleeve is configured to include a switching mechanism and multiple actuators. These actuators are arranged vertically and together form a vertical tubular structure. The inner side of this vertical tubular structure forms a channel for conveying fracturing fluid; the switching mechanism is located within this channel. Taking one actuator as an example, the actuator includes an upper connector 1, which is a tubular structure and vertically positioned. A lower connector 2, also a tubular structure and vertically positioned, is threaded into its bottom. The inner diameter of the lower connector 2 is equal to that of the upper connector 1. An inner cylinder 3 is vertically positioned inside the upper connector 1 and the lower connector 2. Both the upper and lower ends of the inner cylinder 3 are open, and the outer diameter of the inner cylinder 3 is equal to the inner diameter of the upper connector 1. The inner cylinder 3 is connected to the lower connector 2 by N circumferentially arranged pins 4 to lock the initial position of the inner cylinder 3.

[0027] Taking N=3 as an example, the three pins 4 are evenly arranged circumferentially. Taking one of the pins 4 as an example, the main body of the pin 4 is long and rectangular with a square cross-section, and is horizontally positioned during installation. A cavity 303 is formed inside the side wall of the inner cylinder 3. The cavity 303 is a columnar structure and is perpendicular to the inner cylinder 3. A slot 202 is formed on the inner side wall of the lower connector 2. The middle part of the pin 4 is inserted into the cavity 303, with the inner end passing through the inner side wall of the inner cylinder 3 and located inside the inner cylinder 3, and the outer end passing through the outer side wall of the inner cylinder 3 and located in the slot 202. A slip ring 401 is provided in the middle of the pin 4. The slip ring 401 is coaxially arranged with the cavity 303 and can slide along the extension direction of the cavity 303. It can also form a stop with the outer side wall of the cavity 303 to limit the outward sliding of the pin 4. The pin 4 is connected to the inner cylinder 3 via a second elastic element. Under the action of the second elastic element, the pin 4 can slide elastically in the radial direction, facilitating reset. The second elastic element can be set as a first compression spring 5, which is sleeved in the middle of the pin 4 and connected between the inner wall of the slip ring 401 and the inner wall of the cavity 303. The outer end wall of the pin 4 is a slope structure 402, which is inclined upward and outward. A slope structure 203 is provided at the junction of the inner peripheral wall of the slot 202 and the lower connector 2. The slopes of the slope structure 203 and the slope structure 402 are equal, which facilitates guiding the pin 4 out of the slot 202, allowing the inner cylinder 3 to slide axially relative to the lower connector 2, facilitating the correspondence and communication between the second split 301 and the first split 201. Taking two adjacent actuators as an example, when the two adjacent actuators are installed, the lower connector 2 of the upper actuator is threaded onto the upper connector 1 of the lower actuator.

[0028] The lower connector 2 has a first slit 201 on its side wall, which is composed of multiple hole-like structures; the inner cylinder 3 has a second slit 301 on its side wall, which is composed of multiple hole-like structures; the inner peripheral wall of the lower connector 2 near the bottom is a constricted structure 204, with the large end facing upwards; the outer peripheral wall of the bottom of the inner cylinder 3 is a conical annular structure 304, and the taper is equal to the taper of the constricted structure 204. Under the action of the switching mechanism, the inner cylinder 3 can slide along the axial direction and has corresponding first and second positions before and after sliding. Initially, the inner cylinder 3 is in the first position, and the second fracture 301 and the first fracture 201 are misaligned along the axial direction, with the second fracture 301 located above the first fracture 201. When in the second position, the first fracture 201 and the second fracture 301 correspond and are connected. The constriction structure 204 and the conical annular structure 304 overlap, so that the inner cylinder 3 and the lower connector 2 form a stop fit, which facilitates locking the position of the inner cylinder 3. At this time, fracturing fluid can be delivered into the channel. The fracturing fluid is ejected after passing through the second fracture 301 and the first fracture 201 in sequence, realizing the fracturing of the horizontal well section.

[0029] The switching mechanism is rotatable and includes a slide 6. The main body of the slide 6 is a columnar structure, vertically inserted into the inner side of the inner cylinder 3, and can slide axially. Three guide protrusions 601 are evenly distributed circumferentially on the peripheral sidewall of the slide 6. The guide protrusions 601 are strip-shaped structures and extend in a direction parallel to the axis of the slide 6. Each guide protrusion 601 has a groove 602 on its outward-facing sidewall. The grooves 602 are symmetrically arranged about the guide protrusions 601 and are located at the middle of the guide protrusions 601 circumferentially, extending in a direction parallel to the axis of the slide 6. The grooves 602 also extend inward to the peripheral sidewall of the slide 6. Each groove 602 has a stop protrusion 603 on its two opposite sidewalls near the bottom. The inner end of the pin 4 has four inclined structures 403 on its sidewall facing the slip ring 401. 3. The four inclined surface structures 403 are divided into two groups, which are located on the left and right sides of the pin 4 respectively and are symmetrically arranged about the pin 4. The two inclined surface structures 403 in the same group are arranged axially and symmetrically about the pin 4, forming a V-shape. The tip of the V-shape faces the slip ring 401. The inclined surface structure 403 can form a stop engagement with the stop protrusion 603. When the stop protrusion 603 and the upper inclined surface structure 403 form a stop engagement, as the slide 6 moves down, the stop protrusion 603 drives the pin 4 to move inward through the upper inclined surface structure 403 until the stop protrusion 603 moves to the tip of the V-shape formed by the two inclined surface structures 403 in the same group. At this time, the pin 4 moves inward to the limit position, and the inclined surface structure 402 and the inclined surface structure 203 overlap.

[0030] Two sets of guide protrusions 302 are axially spaced on the inner circumferential wall of each inner cylinder 3. Three guide protrusions 302 in the same set are evenly spaced circumferentially, with gaps between adjacent guide protrusions 302. Guide protrusions 302 in different sets are axially corresponding. The guide protrusions are arc-shaped and coaxial with the inner cylinder 3. The top of the upper guide protrusion 302 decreases in height from the middle to both ends, forming two curved surface structures 3021. The two curved surface structures 3021 are symmetrically arranged about the guide protrusions 302. The bottom of the guide protrusion 302 at the bottom is arranged in a V-shape with the tip pointing upwards. The height of the bottom of the guide protrusion 302 at the bottom increases from the middle to both ends, forming two curved surface structures 3021. The two curved surface structures 3021 are symmetrically arranged about the guide protrusion 302 and form a V-shape with the tip pointing downwards. The upper and lower end faces of each guide protrusion 601 are curved surface structures 6011. The upper curved surface structure 6011 extends upwards and inwards, and the lower curved surface structure 6011 extends downwards and inwards. When the slide block 6 slides downward, the lower curved surface structure 6011 can form a guiding engagement with the upper curved surface structure 3021, facilitating the rotation of the switching mechanism. This allows the guide protrusion 601 to rotate to correspond with the notch between adjacent guide protrusions 302 in the same group, thereby achieving automatic position correction. As the slide block 6 continues to slide downward, the guide protrusion 601 can be embedded into the notch. When the slide block 6 slides upward, the upper curved surface structure 6011 can form a guiding engagement with the lower curved surface structure 3021, facilitating the rotation of the switching mechanism. This allows the guide protrusion 601 to rotate to correspond with the notch between adjacent guide protrusions 302 in the same group, thereby achieving automatic position correction. As the slide block 6 continues to slide upward, the guide protrusion 601 can be embedded into the notch.

[0031] The pin 4 is located at the notch between adjacent guide protrusions 302 in the same group, and is located axially between the two groups of guide protrusions 302; three mounting grooves 305 are evenly provided circumferentially on the inner circumferential wall of each inner cylinder 3, and the mounting grooves 305 are located below the two groups of guide protrusions 302; a locking block 7 is inserted into each mounting groove 305, and the locking block 7 is connected to the inner cylinder 3 through a third elastic element. Under the action of the third elastic element, the locking block 7 can slide elastically in the radial direction; the third elastic element can be set as a second compression spring 8. The second compression spring 8 is inserted into the mounting groove 305 during installation, and its two ends are respectively connected between the bottom of the mounting groove 305 and the outer wall of the locking block 7. Under the action of the second compression spring 8, the locking block 7 has a tendency to move inward; the locking blocks 7 on different inner cylinders 3 are misaligned circumferentially with respect to the notch between adjacent guide protrusions 302 in the same group at different angles, so that each actuator is different.

[0032] A cavity 605 is provided near the bottom of the slide block 6, dividing the slide block 6 into upper and lower parts. Multiple connecting rods 606 connect the upper and lower parts, extending vertically and evenly arranged circumferentially. An end 9 is inserted into the bottom of the slide block 6. The main body of the end 9 is a columnar structure and is coaxially arranged with the slide block 6. A fourth elastic element is connected between the slide block 6 and the end 9. Under the action of the fourth elastic element, the slide block 6 can slide elastically relative to the end 9 along the axial direction. A columnar protrusion 607 is coaxially arranged on the top of the cavity 605 on the slide block 6. A fixing sleeve 904 is coaxially arranged on the top of the end 9, and the fixing sleeve 904 is slidably sleeved on the columnar protrusion 607. The fourth elastic element can be a spring 10, which is sleeved on both the columnar protrusion 607 and the fixing sleeve 904.

[0033] Two inclined structures 701 are provided on the inner sidewall of each locking block 7. The two inclined structures 701 are arranged axially and symmetrically about the locking block 7, and together they form a V-shape. The tip of the V-shape is set inward. A V-shaped notch is provided at the connection between the upper inclined structure 701 and the top surface. The tip of the notch is set downward. Three key blocks 901 are evenly spaced along the circumferential sidewall of end 9. Each key block 901 has two inclined structures 9011 on its outer sidewall. The two inclined structures 9011 are arranged axially and together form a V-shape with their tips facing outward. The lower inclined structure 9011 and the upper inclined structure 701 have the same inclination. The upper inclined structure 9011 and the lower inclined structure 701 have the same inclination. A protrusion 9012 is provided on the lower inclined structure 9011. The protrusion 9012 can be embedded into the notch on the locking block 7, thereby realizing the engagement between the locking block 7 and the key block 901. Conical annular structures 608 are provided at the junction of the upper and lower end faces and the peripheral sidewalls of the slide block 6. The larger end of the upper conical annular structure 608 is set downward. When the slide block 6 slides upward, it can form a stop with the lower inclined structure 701, thereby guiding the locking block 7 to insert into the mounting groove 305 and avoiding movement interference. The larger end of the lower conical annular structure 608 is set upward. When the slide block 6 slides downward, it can form a stop with the upper inclined structure 701, thereby guiding the locking block 7 to insert into the mounting groove 305 and avoiding movement interference.

[0034] The end 9 can rotate relative to the slide 6, and can rotate to correspond with the locking blocks 7 on different inner cylinders 3, facilitating the engagement of the key block 901 and the corresponding locking block 7 of the actuator. This allows for fracturing of the target well section, enabling the switching mechanism to adapt to different actuators, simplifying operation steps, reducing construction time, and improving construction efficiency. It can also rotate to correspond with the first slide 602, facilitating the movement of the inner cylinder 3 from the second position to the first position, causing the second fracture 301 and the first fracture 201 to be axially misaligned. The fracturing process can then be repeated, allowing for multiple fracturing operations on the same well section, thus improving applicability.

[0035] An iris assembly 11 is provided between the slide block 6 and the end 9. The iris assembly 11 is located within the cavity 605 and includes multiple sealing blocks 1101. Each sealing block 1101 has a second sliding groove 11011 on its top. The second sliding groove 11011 extends in a direction perpendicular to the slide block 6. During installation, the sealing block 1101 is movably sleeved on the connecting rod 606 through the second sliding groove 11011. Figure 13 As shown, viewed from above, the sealing block 1101 is approximately an obtuse triangle, and the outer wall of the sealing block 1101 is a curved surface, which facilitates its fit with the inner circumferential wall of the inner cylinder 3. In the clockwise direction, the front side wall of the sealing block 1101 is a vertical surface, and the rear side wall of the sealing block 1101, with the part near the front side wall of the sealing block 1101 being a curved surface, allows multiple sealing blocks 1101 to form a complete annular structure, which facilitates its cooperation with the slide block 6 to jointly seal the inner cylinder 3 in the transverse direction.

[0036] To facilitate the formation of a complete annular structure from multiple sealing blocks 1101, a conical annular structure 905 is provided at the junction of the top surface and the peripheral sidewall of the end 9, with the larger end of the conical annular structure 905 facing downwards. A conical annular structure 4 is provided at the bottom of each sealing block 1101, with the taper of the conical annular structure 4 being equal to the taper of the conical annular structure 905, facilitating a guiding fit. When the slide block 6 slides downwards relative to the end 9, the slide block 6 simultaneously drives the sealing block 1101 to slide downwards relative to the end 9. Under the guiding fit between the conical annular structure 4 and the conical annular structure 905, the sealing block 1101 moves outwards and ultimately forms a complete annular structure. To facilitate the automatic reset of the sealing block 1101, a first elastic element is connected between the sealing block 1101 and the connecting rod 606. Under the action of the first elastic element, the sealing block 1101 tends to move inward. The first elastic element can be set as a third compression spring 1102, which is inserted into the slide groove 11011 and its two ends are respectively located between the inner end of the slide groove 11011 and the connecting rod 606.

[0037] To facilitate relative rotation between end 9 and slide 6, a cavity 902 is provided inside end 9 near the top, with a corresponding fixed sleeve 904. A baffle 903 and a baffle 604 are vertically inserted into cavity 902. A telescopic groove 610 is provided at the bottom of the column protrusion 607, extending upwards into the slide 6. During installation, baffle 604 penetrates upwards through the top of end 9 and inserts into the fixed sleeve 904, sliding within the telescopic groove 610 to ensure that the position of baffle 604 within cavity 902 remains constant. The first baffle 903 and the end 9 are fixedly connected; the first baffle 903 and the second baffle 604 divide the first cavity 902 into two non-communicating sub-cavities along the circumference, and an infusion channel 609 is provided inside the slide 6. The infusion channel 609 is connected to one of the sub-cavities formed between the column protrusion 607 and the fixed sleeve 904, so that external liquids, such as hydraulic oil, can be introduced into the sub-cavity. Under the action of hydraulic pressure, the end 9 can be rotated relative to the slide 6 through the first baffle 903, thereby adjusting the key block 901 and the corresponding locking blocks 7 on different inner cylinders 3.

[0038] Optionally, to achieve upper sealing of the well section, a liquid bladder is provided on the slide block 6. The liquid bladder is located above the second fracture 301 and can slide synchronously with the slide block 6 along the axial direction. When the liquid is flushed inside, it can block the inner cylinder 3 laterally.

[0039] In the preparation stage, the actuators are first assembled: the upper connector 1 and the lower connector 2 are threaded together, and then the assembled upper connector 1 and lower connector 2 are set vertically with the upper connector 1 at the top. Then the inner cylinder 3 is inserted into the inner side of the upper connector 1 and the lower connector 2 from top to bottom. Under its own weight or external force, the inner cylinder 3 moves downward and moves until the pin 4 is inserted into the slot 202. The first compression spring 5 is compressed and then released. At this time, the position of the inner cylinder 3 inside the lower connector 2 is locked and located in the first position. Crack 1 201 and Crack 2 301 are axially misaligned, and Crack 2 301 is located above Crack 1 201. Then the different actuators are assembled together: the lower connector 2 and the upper connector 1 of the adjacent actuators are threaded together, so that multiple actuators together form a tubular structure, and the inner side of the tubular structure forms a channel for conveying fracturing fluid. The guide protrusions 302 of different actuators are set accordingly, and the locking blocks 7 on the inner cylinder 3 are misaligned at different angles along the circumferential direction relative to the gaps between adjacent guide protrusions 302 in the same group, making each actuator different.

[0040] During use, the assembled actuators are first placed into the horizontal well; then hydraulic oil is introduced into the cavity 902 through the fluid infusion channel 609. Under the action of hydraulic pressure, the end 9 is rotated relative to the slide 6 through the baffle 903, so that the key block 901 and the locking block 7 on the target inner cylinder 3 are set accordingly; then the switch mechanism is placed into the channel; then the switch mechanism is moved inward along the channel to the target actuator.

[0041] During the movement of the switching mechanism, if the gap between the first guide protrusion 601 and the adjacent second guide protrusion 302 of the same group above the first actuator is misaligned circumferentially, when the slide 6 moves to form a guiding fit between the lower curved structure 6011 and the upper curved structure 3021, as the slide 6 continues to move, under the guidance of the upper curved structure 3021, the switching mechanism rotates to correspond to the gap between the first guide protrusion 601 and the adjacent second guide protrusion 302 of the same group. As the slide 6 continues to slide, the first guide protrusion 601 is embedded in the gap, and at the same time, the pin 4 is inserted into the slide groove 602 and slides along the slide groove 602.

[0042] Before the switching mechanism moves to the target actuator, when the stop protrusion 603 and the upper inclined structure 403 form a stop engagement, as the slide 6 continues to move, the stop protrusion 603 drives the pin 4 to move inward through the upper inclined structure 403, and the first compression spring 5 is compressed synchronously until the stop protrusion 603 moves to the tip of the V-shape formed by the two inclined structures 403 in the same group. At this time, the pin 4 moves inward to its limit position. Since the outer end of the pin 4 is still in the slot 202 and the inner cylinder 3 is not subjected to downward force, the inner cylinder 3 will not move. After the stop protrusion 603 passes the tip of the V-shape formed by the two inclined structures 403 in the same group, as the slide 6 continues to move, the first compression spring 5 is released, driving the pin 4 to reset. And since the key block 901 only corresponds to the locking block 7 on the target inner cylinder 3, the key block 901 will not interfere with the movement of the locking block 7 on other inner cylinders 3, ensuring that the switching mechanism can pass smoothly through other actuators.

[0043] When the switching mechanism moves to the target actuator, the protrusion 9012 inserts into the notch on the locking block 7, causing the key block 901 and the locking block 7 to engage. At this time, the position of the end 9 is locked. The stop protrusion 603 moves to the tip of the V-shape formed by the two inclined structures 403 in the same group. The pin 4 moves inward to its limit position, and the inclined structure 402 and the inclined structure 203 overlap. Then, the slide 6 continues to move, and the slide 6 simultaneously moves the blocking block 1101 closer to the end 9. Under the guidance of the conical annular structure 4 and the conical annular structure 905, the third compression spring 1102 is compressed, and the blocking block 1101 moves outward, finally forming a complete circular structure, which, together with the slide 6, cuts off the channel laterally. Then, the slide 6 continues to move, and the slide 6 simultaneously passes the key block 901. The engagement between 01 and the locking block 7 causes the inner cylinder 3 to move away from the upper connector 1. The inner cylinder 3 drives the pin 4 to move along the inclined structure 203, guiding the pin 4 to disengage from the slot 202. The outer end of the pin 4 then pushes against the inner circumferential wall of the lower connector 2 and slides along the inner circumferential wall of the lower connector 2. When the constriction structure 204 and the conical annular structure 304 overlap, the inner cylinder 3 reaches its limit position downward. At this time, the second fracture 301 and the first fracture 201 correspond and are connected. The switching mechanism stops moving and then liquid is flushed into the liquid bladder to expand it and block the channel laterally. At this time, the target well section is blocked into a closed chamber by the annular structure composed of the liquid bladder, the sealing block 1101 and the slide 6. Then, fracturing fluid is filled into the closed chamber. The fracturing fluid is ejected after passing through the second fracture 301 and the first fracture 201 in sequence, thus achieving fracturing of the target well section.

[0044] When secondary fracturing is required on the target well section, the fluid inside the liquid bladder is first retracted, causing the bladder to contract. Then, hydraulic oil is introduced into cavity 902 through the fluid inlet channel 609. Under hydraulic pressure, the end 9 rotates relative to the slide block 6 via the baffle 903, aligning the key block 901 and the pin 4. Alternatively, hydraulic oil can be drawn from cavity 902 through the fluid inlet channel 609. Under differential pressure, the end 9 rotates relative to the slide block 6 via the baffle 903, aligning the key block 901 and the pin 4. Then, the slide block... As the end 9 moves away from the 6, the third compression spring 1102 is released, causing the sealing block 1101 to move inward, thus resetting the sealing block 1101. When the key block 901 moves to the stop of the pin 4, as the slide 6 continues to move, the slide 6 simultaneously drives the inner cylinder 3 to approach the upper connector 1, causing the second fracture 301 and the first fracture 201 to gradually misalign until the pin 4 is reinserted into the slot 202. Then, the process of making the second fracture 301 and the first fracture 201 correspond and connect is repeated. Then, fracturing fluid is injected into the sealed chamber to achieve secondary fracturing of the target well section.

[0045] If the target well section needs to be fracturing three or more times, the above-mentioned two-stage fracturing process can be repeated.

[0046] It should be noted that when the switching mechanism is inside the channel, hydraulic oil can be input into the cavity 902 through the fluid inlet channel 609. Under the action of hydraulic pressure, the end 9 rotates relative to the slide 6 through the baffle 903, so that the key block 901 and the locking block 7 on the other target inner cylinder 3 are set accordingly. Alternatively, hydraulic oil can be drawn from the cavity 902 through the fluid inlet channel 609. Under the action of pressure difference, the end 9 rotates relative to the slide 6 through the baffle 903, so that the key block 901 and the locking block 7 on the other target inner cylinder 3 are set accordingly. This allows the switching mechanism to be adapted to different actuators inside the well, which simplifies the operation steps, reduces construction time, and improves construction efficiency.

[0047] In a further embodiment, to improve the sealing performance of the iris assembly 11 when it laterally seals the inner cylinder 3, an elastic layer is provided on the side wall of each sealing block 1101. The elastic layer can be made of an elastic material, such as rubber. Thus, when multiple sealing blocks 1101 form a complete annular structure, the gaps can be filled by the deformation of the elastic layer, thereby improving the sealing effect.

[0048] In other embodiments, to improve the sealing performance of the iris assembly 11 when it laterally blocks the inner cylinder 3, an annular elastic layer 2 can be provided at the contact position between the inner cylinder 3 and the blocking block 1101. The elastic layer 2 can be made of an elastic material, such as rubber. In this way, when multiple blocking blocks 1101 form a complete annular structure, the gaps can be filled by the deformation of the elastic layer 2, thereby improving the sealing effect.

[0049] In other embodiments, to improve the sealing performance of the iris assembly 11 when it laterally blocks the inner cylinder 3, the sealing blocks 1101 can be made of an elastic material, such as rubber. Thus, when multiple sealing blocks 1101 form a complete annular structure, the gaps can be filled by the deformation of the sealing blocks 1101 themselves, improving the sealing effect.

[0050] In other embodiments, to achieve automatic reset of the end 9 after it rotates relative to the slide 6, a second elastic element is connected between the first baffle 903 and the second baffle 604. After the end 9 rotates relative to the slide 6, the end 9 tends to rotate to the reset position under the action of the second elastic element.

[0051] Specifically, the second elastic element can be set as a torsion spring 12, which is inserted into the first baffle 903 and fixedly connected to the first baffle 903 and the second baffle 604 at both ends respectively.

[0052] During use, after the end 9 rotates relative to the slide 6, the torsion spring 12 deforms and stores force; during the process of restoring normal pressure in the cavity 902, the torsion spring 12 synchronously drives the end 9 to rotate relative to the slide 6 through the baffle 903, thereby achieving reset.

[0053] In other embodiments, to improve the connection stability between the upper connector 1 and lower connector 2 of the same actuator, and between the lower connector 2 and upper connector 1 of adjacent actuators, the upper connector 1 and lower connector 2 of the same actuator, and between the lower connector 2 and upper connector 1 of adjacent actuators, are fixedly connected by fasteners.

[0054] Specifically, the fastener can be equipped with an anti-rotation pin. For the upper connector 1 and lower connector 2 of the same actuator, the anti-rotation pin penetrates the side wall of the upper connector 1 radially inward during installation, and is threaded or friction-inserted into the side wall of the lower connector 2. For the lower connector 2 and upper connector 1 of adjacent actuators, the anti-rotation pin penetrates the side wall of the lower connector 2 radially inward during installation, and is threaded or friction-inserted into the side wall of the upper connector 1.

[0055] In other embodiments, to improve the sealing between the upper connector 1 and the lower connector 2, a sealing element, such as a sealing ring, is provided at the connection between the upper connector 1 and the lower connector 2 to achieve a seal.

[0056] In other embodiments, the channel can be blocked on one side by replacing the liquid bladder with an existing packer or soluble bridge plug. In this case, both the second crack 301 and the first crack 201 are located below the end 9, and the packer or soluble bridge plug is located below the first crack 201.

[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The above embodiments are merely illustrative of several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A full-bore, unlimited-stage fracturing sleeve for horizontal wells, characterized in that, Includes a switching mechanism and multiple actuators; The actuator includes an upper connector (1) and a lower connector (2). An inner cylinder (3) is provided inside the lower connector (2). The inner cylinder (3) is connected to the lower connector (2) by N pins (4) arranged circumferentially. The pins (4) can slide elastically in the radial direction. A first slit (201) is provided on the lower connector (2). A second slit (301) is provided on the inner cylinder (3). Under the action of the switching mechanism, the inner cylinder (3) can slide axially and has a first position and a second position before and after sliding. When it is in the first position, the second slit (301) and the first slit (201) are misaligned. When it is in the second position, the first slit (201) and the second slit (301) are connected to each other, and the inner cylinder (3) and the lower connector (2) form a stop fit. The switching mechanism is rotatable and includes a slide (6), which is located inside the inner cylinder (3) and can slide along the axial direction; N guide protrusions (601) are arranged circumferentially on the slide (6); each guide protrusion (601) is provided with a groove (602), which extends axially; the pin (4) can be slidably inserted into the groove (602); each groove (602) is provided with a stop protrusion (603), which can form a stop engagement with the pin (4) and can drive the pin (4) to move inward; two sets of guide protrusions (302) are arranged axially at intervals on the inner circumferential wall of each inner cylinder (3), and the N guide protrusions (302) in the same set are arranged circumferentially at intervals, and the guide protrusions (302) can form a guiding engagement with the guide protrusions (601); the pin (4) is located in the same set of adjacent guide protrusions (302). The gap between the two sets of guide protrusions (302) is located between the two sets of guide protrusions (302); N locking blocks (7) are arranged circumferentially on the inner wall of each inner cylinder (3). The locking blocks (7) can slide elastically in the radial direction. The locking blocks (7) on different inner cylinders (3) are misaligned at different angles relative to the gap between adjacent guide protrusions (302) in the same set of guide protrusions (302) in the circumferential direction; an end (9) is inserted on the slide (6); the slide (6) can slide elastically in the axial direction relative to the end (9); N key blocks (901) are arranged circumferentially on the side wall of the end (9). The end (9) can rotate relative to the slide (6) and can rotate until the key block (901) and the first slide groove (602) or the locking blocks (7) on different inner cylinders (3) are correspondingly arranged; an iris assembly (11) is arranged between the slide (6) and the end (9). The iris assembly (11) can block the inner cylinder (3) in the transverse direction.

2. The horizontal well full-bore unlimited-stage fracturing sliding sleeve according to claim 1, characterized in that, The iris assembly (11) includes multiple blocking blocks (1101), which are arranged circumferentially and can be movably fitted onto the slide (6) and can fit against the inner circumferential wall of the inner cylinder (3). Each blocking block (1101) is connected to the slide (6) through a first elastic element. Under the action of the first elastic element, the blocking block (1101) has a tendency to move inward.

3. The horizontal well full-bore unlimited-stage fracturing sliding sleeve according to claim 2, characterized in that, Each sealing block (1101) has an elastic layer on its sidewall.

4. The horizontal well full-bore unlimited-stage fracturing sliding sleeve according to claim 2, characterized in that, An annular elastic layer 2 is provided at the contact position between the inner cylinder (3) and the sealing block (1101).

5. The horizontal well full-bore unlimited-stage fracturing sliding sleeve according to claim 2, characterized in that, The sealing block (1101) is made of elastic material.

6. The horizontal well full-bore unlimited-stage fracturing sleeve according to claim 5, characterized in that, The elastic material is rubber.

7. The horizontal well full-bore unlimited-stage fracturing sliding sleeve according to claim 1, characterized in that, The end (9) has a cavity 1 (902) inside. A baffle 1 (903) and a baffle 2 (604) are inserted in the cavity 1 (902). The baffle 1 (903) is fixedly connected to the end (9), and the baffle 2 (604) is connected to the slide (6). The baffle 1 (903) and the baffle 2 (604) divide the cavity 1 (902) into two non-communicating sub-cavities. One of the sub-cavities is configured to receive liquid from the outside.

8. The horizontal well full-bore unlimited-stage fracturing sleeve according to claim 7, characterized in that, A first elastic element is connected between baffle one (903) and baffle two (604). After the end (9) rotates relative to the slide (6), the end (9) tends to rotate to the reset position under the action of the first elastic element.

9. The horizontal well full-bore unlimited-stage fracturing sleeve according to claim 1, characterized in that, The upper connector (1) and lower connector (2) of the same actuator are threaded together; the lower connector (2) and upper connector (1) of adjacent actuators are threaded together.

10. The horizontal well full-bore unlimited-stage fracturing sliding sleeve according to claim 9, characterized in that, The upper connector (1) and lower connector (2) of the same actuator are fixedly connected by fasteners, as are the lower connector (2) and upper connector (1) of adjacent actuators.

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