Horizontal well repairing and reinforcing device by lowering small casing

Abstract

The invention relates to the technical field of oil and gas well hanging small casing pipe well repairing, in particular to a horizontal well repairing and reinforcing device by lowering a small casing pipe. The device for repairing and reinforcing the horizontal well through the lower small casing pipe comprises the small casing pipe, a packing device is arranged on the small casing pipe, the packing device comprises a packer, one end of the packer is connected with a differential pressure sliding sleeve, a first centralizer is arranged between the packer and the differential pressure sliding sleeve, and a second centralizer is arranged between the packer and the differential pressure sliding sleeve. The other end of the packer is connected with a sealing device used for sealing one port of the small casing pipe, and a second centralizer is arranged between the packer and the sealing device. According to the device for repairing and reinforcing the horizontal well by lowering the small casing pipe, the small casing pipe is lowered to the position above an oil layer, the oil layer is blocked through the packer clamping and sealing technology, well cementation cement can flow back above the packer and be solidified, a firm cement sheath is formed, and therefore an oil and gas layer is effectively isolated and protected and prevented from being polluted by well cementation cement paste.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well workover technology, and particularly to a device for repairing and reinforcing horizontal wells with a small casing. Background Technology

[0002] A horizontal well is a well whose borehole trajectory reaches or nearly reaches a horizontal state underground and maintains a certain length of horizontal section. Horizontal wells are mainly used for the development of unconventional oil and gas reservoirs such as thin-layer reservoirs, low-permeability reservoirs, and fractured oil and gas reservoirs, offering advantages such as improved recovery rate, increased oil and gas production, and reduced drilling quantity. The horizontal well's borehole trajectory maintains a certain length of horizontal section within the oil-bearing layer, significantly increasing the contact area between the wellbore and the oil layer, thus improving the recovery rate of a single well. During oilfield development and production, geological factors such as abnormal formation pressure, fault activity, and lithological interface sliding may cause additional stress on the casing, leading to deformation, fracture, or leakage, resulting in water production in horizontal wells and affecting oil production efficiency and quality. Therefore, for well sections where casing damage has occurred, cementing repair operations are necessary.

[0003] In existing technologies, suspended small casing is commonly used to repair wells with casing damage. The basic principle of suspended small casing technology for wells with casing damage is to run a new casing with a smaller diameter into the damaged section of the well, and then seal the annulus between the new casing and the original casing through cementing operations, thereby forming a new and robust wellbore channel; cementing slurry is injected into the wellbore channel, and after it solidifies, a stable cemented tubing string is formed for subsequent production use.

[0004] Chinese utility model patent CN205370504U, with an authorization announcement date of 2016 / 07 / 06, discloses a plugging process string suitable for cementing small casing wells in horizontal wells. The disclosed plugging process string for cementing small casing wells in horizontal wells includes a drill pipe, a small casing connected to the bottom of the drill pipe, a ball seat connected to the bottom of the small casing, and a float shoe connected to the lower end of the ball seat via a float collar. The float shoe, float collar, small casing, and ball seat are all housed inside a precision microporous sand control tube. The upper end of the precision microporous sand control tube, connected sequentially from top to bottom, is connected to the bottom end of a large casing. A hanger is connected to the outer wall of the upper end of the small casing, and the hanger is suspended from the inner wall of the bottom end of the large casing. The drill pipe passes through the large casing. The annulus between the inner cavity of the precision microporous sand control tube and the small casing is filled with injected plugging cement, and simultaneously, the annulus between the outer surface of the precision microporous sand control tube and the open hole well wall is also filled with injected plugging cement.

[0005] Chinese utility model patent CN203499632U, with an authorization announcement date of March 26, 2014, discloses a tubing string for repairing suspended small casing in horizontal wells with casing damage. This tubing string includes drill pipe plugs, drill pipe, a forward / reverse threaded suspension connector, a hollow plug assembly, a string of small casings, a helical rigid centralizer, a pressure joint, a float shoe, a float collar, and a vortex tube. Helical rigid centralizers are threadedly connected between the small casings. During cementing, the tubing string is lowered to the section below the oil layer, and then cement slurry is injected.

[0006] Chinese invention applications CN113294135A and 2021 / 08 / 24 disclose a method for reshaping a casing within a horizontal well. The method includes the following steps: running a small casing or tubing and a hanger into the wellbore; sealing the original orifices and fractures in the wellbore with a polymer plugging agent; cementing the small casing or tubing with cementing mud and allowing it to set; and performing a pressure test on the small casing or tubing according to subsequent fracturing requirements. In this invention, a special cement slurry is used to cement the new casing with the original casing, ensuring that there is no pressure cross-contamination between sections during subsequent fracturing, thus guaranteeing the smooth completion of fracturing and modification of each section of the entire horizontal well.

[0007] All three patents involve cementing in the oil-bearing well section, which not only causes oil layer contamination but also requires re-communication with the oil layer, increasing cementing costs without improving cementing efficiency. Summary of the Invention

[0008] The purpose of this invention is to provide a device for repairing and reinforcing horizontal wells with a small casing, so as to solve the problem in the prior art that cementing in the oil layer section affects oil production efficiency and oil quality.

[0009] To address the aforementioned problems, the present invention provides a horizontal well repair and reinforcement device with a small casing, employing the following technical solution: A device for repairing and reinforcing horizontal wells with a small casing is characterized in that it includes a small casing, the small casing is connected to a differential pressure sleeve via a drillable float collar, the lower end of the differential pressure sleeve is connected to a packer, the packer includes a packer, a first centralizer is provided between the packer and the differential pressure sleeve, the other end of the packer is connected to a sealing device for sealing one end of the small casing, and a second centralizer is provided between the packer and the sealing device.

[0010] Furthermore, the first straightener includes a connecting cylinder and a straightener body, both of which are tubular structures. The straightener body is sleeved on the lower part of the connecting cylinder and has a clearance fit with the outer surface of the connecting cylinder.

[0011] Furthermore, the outer cylindrical surface of the connecting cylinder is a stepped surface, larger at the top and smaller at the bottom. The upper end of the connecting cylinder is provided with an internal thread to match the external thread provided at the lower end of the central cylinder, and the lower end of the connecting cylinder is provided with an external thread to connect the packer.

[0012] Furthermore, the straightening body is cylindrical and its diameter is slightly larger than the outer diameter of the other components of the sealing device, and a set of inclined grooves at an angle to its center line are uniformly arranged on the outer surface of the straightening body.

[0013] Furthermore, the packer includes a rubber sleeve seat. The packer is connected to the connecting cylinder via an internal thread on the upper end of the rubber sleeve seat and an external thread on the lower end of the connecting cylinder. The rubber sleeve seat is provided with a rubber sleeve, and a setting mechanism is connected to the rubber sleeve. The setting mechanism is connected to a locking mechanism.

[0014] Furthermore, the second straightener includes an upper connector, a lower connector, and a straightener body disposed between the upper connector and the lower connector. The straightener body is sleeved on the lower part of the upper connector and has a clearance fit with the outer surface of the lower connector.

[0015] Furthermore, the upper connector is a tubular structure, and the outer surface of the upper connector is a stepped surface, wider at the top and narrower at the bottom. The upper end of the upper connector is provided with an internal thread for connecting to the locking mechanism, and the lower end of the upper connector is provided with an external thread for connecting to the external thread provided at the upper end of the lower connector. The outer surface of the lower connector is a stepped surface, wider at the top and narrower at the bottom, and the lower end of the lower connector is provided with an external thread for connecting to the sealing device.

[0016] Furthermore, the straightening body is cylindrical and its diameter is slightly larger than the outer diameter of the other components of the sealing device, and a set of inclined grooves at an angle to its center line are uniformly arranged on the outer surface of the straightening body.

[0017] Furthermore, the sealing device is a drillable ball seat, which has the same structure as the drillable floating hoop.

[0018] Furthermore, the differential pressure sleeve and the drillable floating hoop are connected by a threaded connection.

[0019] Beneficial Effects: The small casing repair and reinforcement device of this invention is a pioneering invention. This scheme lowers a small casing into a damaged horizontal well to provide support for the new wellbore. The packer device on the small casing includes a packer, a differential pressure sleeve, a first centralizer, and a second centralizer. The packer forms a seal at a specific location, confining the injected cement slurry within the section to be reinforced under the packer's sealing effect. The flow holes in the differential pressure sleeve guide the injected cement slurry. The first and second centralizers reduce the friction area between the centralizer and the wellbore. This invention's small casing repair and reinforcement device lowers the small casing above the oil layer, using packer sealing technology to seal the oil layer. The cement slurry flows back and solidifies above the packer, forming a strong cement ring, effectively isolating and protecting the oil and gas layer from contamination by the cement slurry. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the tubular structure of the present invention; Figure 2 for Figure 1 Schematic diagram of the middle sealing device; Figure 3 for Figure 2 Schematic diagram of the structure of the differential pressure sliding sleeve; Figure 4 for Figure 2 A schematic diagram of the structure of the first central stabilizer; Figure 5 for Figure 2 A schematic diagram of the packer structure; Figure 6 for Figure 2 A schematic diagram of the structure of the second central stabilizer; Figure 7 : Schematic diagram of the well completion casing structure of the present invention.

[0021] In the diagram: 1. Tubing; 2. Casing hanger; 3. Small casing; 4. Drillable float collar; 5. Packer; 6. Drillable ball seat; 7. Bell mouth; 8. Casing; 9. Screen pipe; 10. Oil layer; 11. Lost section of casing-damaged well; 12. Annular space 12 between casing 8 and small casing 3; 5-1. Central cylinder; 5-2. Differential pressure sliding sleeve; 5-2-1. Sliding sleeve; 5-2-2. Pin; 5-2-3. Sealing ring; 5- 2-4, Sealing ring; 5-2-5, Flow hole; 5-3, First stabilizer; 5-3-1, Connecting cylinder; 5-3-2, Stabilizer; 5-3-3, Inclined groove; 5-4, Packer; 5-4-1, Glue sleeve seat; 5-4-2, Glue sleeve; 5-4-3, Sealing mechanism; 5-4-4, Locking mechanism; 5-5, Second stabilizer; 5-5-1, Upper connector; 5-5-2, Stabilizer; 5-5-3, Lower connector. Detailed Implementation

[0022] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0023] The present invention relates to a small casing repair and reinforcement horizontal well device that lowers a small casing above the oil layer and uses a packer to seal it, so that the cementing cement solidifies into a ring above the oil layer, protecting the oil and gas layer from cement slurry contamination.

[0024] As a basic solution, the present invention provides a small casing repair and reinforcement device for horizontal wells, comprising a small casing 3, such as... Figure 1 As shown, the small casing 3 is the foundation of the entire device, providing a solid base for installing the packer 5 and other components. It also provides a stable channel for subsequent oil and gas extraction or injection of cementing slurry. The small casing 3 is equipped with the packer 5, such as... Figure 2 As shown, the packer device 5 includes a packer 5-4, which is the core component of the packer device 5. Through its internal sealing elements and elastic materials, it can form an effective sealing layer inside the casing 8. One end of the packer 5-4 is connected to a differential pressure sleeve 5-2, which is mainly used to control the flow path and flow rate of the cementing slurry. A first centralizer 5-3 is provided between the packer 5-4 and the differential pressure sleeve 5-2. The other end of the packer 5-4 is connected to a sealing device to seal one port of the small casing 3. A second centralizer 5-5 is provided between the packer 5-4 and the sealing device. The two centralizers ensure the stability and accuracy of the packer 5-4 and other components inside the casing 8, and reduce the friction area between them and the inner wall of the casing 8.

[0025] In a preferred embodiment, the differential pressure sleeve 5-2 includes a central cylinder 5-1, such as... Figure 3 As shown, a sliding sleeve 5-2-1 is provided on the central cylinder 5-1. The central cylinder 5-1 provides a robust support platform for installing and fixing the sliding sleeve 5-2-1 and other related components. Sealing rings 5-2-3 and 5-2-4 are provided at both ends of the contact surface between the sliding sleeve 5-2-1 and the central cylinder 5-1. A flow hole 5-2-5 is provided on the cylinder wall of the central cylinder 5-1 between the sealing rings 5-2-3 and 5-2-4. The sliding sleeve 5-2-1 can slide on the central cylinder 5-1, thereby opening or closing the flow hole 5-2-5 to control the cement slurry. The sealing rings are key components in the differential pressure sliding sleeve 5-2; their main function is to prevent leakage between the sliding sleeve 5-2-1 and the central cylinder during the setting process of the packer 5-4.

[0026] In a preferred embodiment, the outer cylindrical surface of the central cylinder 5-1 is designed as a stepped surface, wider at the top and narrower at the bottom. This design not only enhances the structural strength of the central cylinder 5-1 but also facilitates the fixing of the sliding sleeve 5-2-1. One section of the sliding sleeve 5-2-1 is fixed to the step of the central cylinder 5-1 by a pin 5-2-2. The upper end of the central cylinder 5-1 is provided with an internal thread, and the lower end is provided with an external thread. The internal and external threads are used to connect and fix other components or tools. The internal thread is used to connect the components or tools on the upper part of the sealing device 5, while the external thread is used to connect the components or tools on the lower part of the differential pressure sliding sleeve 5-2. This design allows the differential pressure sliding sleeve 5-2 to be flexibly combined and disassembled with other components or tools.

[0027] In a preferred embodiment, the first centralizer 5-3 includes a connecting cylinder 5-3-1 and a centralizer body 5-3-2, such as... Figure 4 As shown, both the connecting cylinder 5-3-1 and the centralizer 5-3-2 are tubular structures. The internal channel of the connecting cylinder 5-3-1 allows fluid or material to pass through smoothly. The centralizer 5-3-2 is sleeved on the lower part of the connecting cylinder 5-3-1 and has a clearance fit with the outer surface of the connecting cylinder 5-3-1. Through the contact between its outer surface and the inner wall of the casing 8, it provides additional support and guidance. This design allows the first centralizer 5-3 to be firmly fixed on the packer 5-4 and effectively protects the other components of the invention from wear during the well running process, thereby ensuring the reliability of the packing effect.

[0028] In a preferred embodiment, the connecting cylinder 5-3-1 serves as an intermediate component, with its upper internal thread engaging with the lower external thread of the central cylinder 5-1 to achieve a secure connection. Simultaneously, the lower external thread of the connecting cylinder 5-3-1 connects to the packer 5-4, ensuring that the packer 5-4 is stably fixed to the connecting cylinder 5-3-1. This design allows the connecting cylinder 5-3-1, the central cylinder 5-1, and the packer 5-4 to form a stable integrated structure, collectively fulfilling the function of the packer device 5.

[0029] In one preferred embodiment, the packer 5-4 includes a rubber sleeve seat 5-4-1, such as... Figure 5As shown, the rubber sleeve seat 5-4-1 is used to fix and support the rubber sleeve 5-4-2. The upper end of the rubber sleeve seat 5-4-1 is provided with an internal thread for connecting with the external thread at the lower end of the connecting sleeve 5-3-1, thereby achieving a firm connection between the packer 5-4 and the connecting sleeve 5-3-1, allowing the packer 5-4 to be stably suspended in the casing 8. The rubber sleeve 5-4-2 is the core component of the packer 5-4, directly contacting the inner wall of the wellbore, and achieving the packing function through expansion and contraction. When the packer 5-4 is set, the rubber sleeve 5-4-2 is compressed and expanded, thus tightly fitting against the inner wall of the wellbore, forming an effective sealing layer. The rubber sleeve 5-4-2 is connected to a setting mechanism 5-4-3, which is the power component of the packer 5-4. When setting is required, it pushes the rubber sleeve 5-4-2 to expand and fit against the inner wall of the wellbore. The setting mechanism 5-4-3 typically achieves the setting operation of the rubber cartridge 5-4-2 through hydraulic, pneumatic, or mechanical force. The locking mechanism 5-4-4 is the locking component in the packer 5-4; it is responsible for locking the rubber cartridge 5-4-2 in the correct position after setting, preventing movement or failure of the rubber cartridge 5-4-2 due to fluid pressure or other external factors. The locking mechanism 5-4-4 typically locks the rubber cartridge 5-4-2 through mechanical jaws, threaded connections, or friction. The setting mechanism 5-4-3 and the locking mechanism 5-4-4 cooperate to ensure that the rubber cartridge 5-4-2 is stably locked in the correct position after setting, preventing packer failure due to external factors. The packer used in this embodiment is a pressure-setting type; specifically, the packer model used is Y341.

[0030] As a preferred implementation method, such as Figure 6 As shown, the upper connector 5-5-1 and the lower connector 5-5-3 serve as the upper and lower connecting components of the second centralizer 5-5, respectively. They are securely connected to other devices via threaded connections and jointly support and fix the centralizer 5-5-2. The centralizer 5-5-2 is fitted onto the lower part of the upper connector 5-5-1 and maintains a clearance fit with the outer surface of the lower connector 5-5-3. This design allows the centralizer 5-5-2 to move freely in the wellbore and adapt to changes in the wellbore shape, while reducing contact friction with other devices.

[0031] In a preferred embodiment, the upper connector 5-5-1 is a tubular structure with a stepped outer surface, wider at the top and narrower at the bottom. The lower connector 5-5-3 also has a stepped outer surface. The upper connector 5-5-1 is connected to the locking mechanism 5-4-4 via its internal thread and to the lower connector 5-5-3 via its external thread. The lower connector 5-5-3 is connected to the sealing device via its external thread. This connection method not only enhances the overall structural strength but also ensures sealing performance and operational safety within the wellbore. Furthermore, the stepped surface design between the components facilitates fitting and positioning, improving installation accuracy and efficiency.

[0032] In a preferred embodiment, the stabilizer is designed as a cylinder with a diameter slightly larger than the outer diameter of the other components of the packer 5. This design allows the stabilizer to have sufficient contact area with the inner wall of the sleeve 8, thereby providing stable support. The outer surface of the stabilizer is uniformly provided with a set of inclined grooves 5-3-3 at an angle to its centerline. These inclined grooves 5-3-3 can rotate when the packer 5 is lowered into the sleeve 8, reducing the downward resistance of the device and facilitating the smooth movement of the device in the sleeve 8.

[0033] In a preferred embodiment, the sealing device is a drillable ball seat 6, which has the same structure as a drillable float hoop, and the structure of the drillable float hoop is the same as that of a regular float hoop. Its internal components are made of drillable material. The installation direction of the drillable ball seat is opposite to that of the drillable float hoop, allowing liquid from the lower part of the tubing string to enter the tubing string, but blocking it in the opposite direction. The drillable ball seat 6 provides a reliable sealing surface to prevent leakage of fluids (such as oil, gas, water, etc.) within the casing 8 during repair. The drillable ball seat 6 is typically designed with a robust ball and seat. The ball can withstand the pressure from the fluid within the casing 8, while the seat provides stable support. When it is necessary to drill through the ball seat, the drill bit can be used for milling through the hole in the center of the ball seat without damaging the overall sealing structure.

[0034] In a preferred embodiment, a drillable float collar 4 is connected to the small casing 3 via a differential pressure sleeve 5-2, and the connection between the differential pressure sleeve 5-2 and the drillable float collar 4 is a threaded connection. The design of the drillable float collar 4 prevents backflow of cementing slurry during injection and allows it to be drilled through by the drill string when necessary for subsequent operations.

[0035] The implementation process of this embodiment is as follows: The horizontal well repair and reinforcement device of the present invention is divided into four stages, namely the first stage of running the small casing 3, the second stage of setting the packer 5-4, the third stage of cementing, and the fourth stage of connecting the oil layer 10.

[0036] The specific process of lowering the small casing 3 in the first stage is as follows: First, the tubing 1, casing 8 hanger 2, small casing 3, drillable float collar 4, packer 5, and drillable ball seat 6 are sequentially connected by threads, and then the entire device is lowered into the well. During the well lowering process, the first and second stabilizers on the packer 5, because their outer diameters are slightly larger than the outer diameters of other rigid bodies, and because their outer cylindrical surfaces are evenly distributed with inclined grooves 5-3-3, will contact the inner wall of the casing 8 and rotate. This design ensures that the other components of the packer 5 will not directly contact the inner wall of the casing 8, thereby preventing the packer 5 from being worn during the well lowering process.

[0037] The specific process of setting the packer 5-4 in the second stage is as follows: After the device is lowered to the oil layer 10, the packer 5 is positioned between the lost circulation section 11 of the casing and the screen pipe 9. At this time, the casing 8 hanger 2 is set, and the tubing 1 is pressurized. Since the drillable ball seat 6 blocks the lower part of the small casing 3, hydraulic pressure flows through the central channel of the packer 5-4 on the packer 5. Under pressure, the setting mechanism 5-4-3 pushes up the compressed rubber cylinder 5-4-2, sealing the casing annular space 12 between the casing 8 and the small casing 3. Subsequently, the locking mechanism 5-4-4 locks the setting mechanism 5-4-3. Continue to increase the pressure in the oil pipe 1. The pressure acts on the inner step at the bottom of the sliding sleeve 5-2-1, shearing the pin 5-2-2 and causing the sliding sleeve 5-2-1 to move downward, thereby exposing the flow hole 5-2-5 on the central cylinder 5-1 and opening the channel between the casing annular space 12 between the casing 8 and the small casing 3.

[0038] The specific process of the third stage of cementing is as follows: Cementing slurry is injected from the surface through tubing 1. The cementing slurry passes through the drillable float collar 4, and then through the flow hole 5-2-5 of the integrated sealing sleeve 5-2-1 into the annular space 12 of the casing 8. Since the annular space of the casing 8 below the flow hole 5-2-5 has been sealed by the rubber sleeve 5-4-2, the cementing slurry will rise along the annular space of the casing 8 to a certain height above the lost circulation section 11 of the casing 8. Under the action of the drillable float collar 4, the cement cannot return, and after it solidifies, it forms a cementing annulus, sealing the lost circulation section 11 of the casing 8. Afterwards, the casing 8 hanger 2 is reversed, and the hanger mandrel and tubing 1 are pulled out of the wellhead.

[0039] The specific process of connecting oil layer 10 in the fourth stage is as follows: By drilling through tubing 1 with a drill bit, the residual cement, drillable float collar 4, and drillable ball seat 6 of the small casing 3 are removed, thereby connecting the oil layer 10. For example... Figure 7 As shown, in subsequent operations such as sand flushing of the lower casing, the bell mouth 7 plays a guiding role, which helps the tool return smoothly to the small casing 3 and prevents the drill from getting stuck.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A device for repairing and reinforcing horizontal wells with a small casing, characterized in that, The device includes a small sleeve, which is connected to a differential pressure sleeve via a drillable floating hoop. The lower end of the differential pressure sleeve is connected to a sealing device, which includes a packer. A first centralizer is provided between the packer and the differential pressure sleeve. The other end of the packer is connected to a sealing device to seal one end of the small sleeve. A second centralizer is provided between the packer and the sealing device.

2. The device for repairing and reinforcing horizontal wells with a small casing as described in claim 1, characterized in that, The first stabilizer includes a connecting cylinder and a stabilizer body. Both the connecting cylinder and the stabilizer body are tubular structures. The stabilizer body is sleeved on the lower part of the connecting cylinder and has a clearance fit with the outer surface of the connecting cylinder.

3. The device for repairing and reinforcing horizontal wells with a small casing as described in claim 2, characterized in that, The outer cylindrical surface of the connecting cylinder is a stepped surface, which is larger at the top and smaller at the bottom. The upper end of the connecting cylinder is provided with an internal thread to match the external thread provided at the lower end of the central cylinder. The lower end of the connecting cylinder is provided with an external thread to connect the packer.

4. The device for repairing and reinforcing horizontal wells with a small casing as described in claim 2 or 3, characterized in that, The straightening body is cylindrical and its diameter is slightly larger than the outer diameter of the other components of the sealing device. A set of inclined grooves at an angle to its center line are uniformly arranged on the outer surface of the straightening body.

5. The device for repairing and reinforcing horizontal wells with a small casing as described in claim 1, characterized in that, The packer includes a rubber sleeve seat, and the packer is connected to the connecting cylinder by an internal thread at the upper end of the rubber sleeve seat and an external thread at the lower end of the connecting cylinder. The rubber sleeve seat is provided with a rubber sleeve, and a setting mechanism is connected to the rubber sleeve. The setting mechanism is connected to a locking mechanism.

6. The device for repairing and reinforcing horizontal wells with a small casing as described in claim 5, characterized in that, The second straightener includes an upper connector, a lower connector, and a straightener body disposed between the upper connector and the lower connector. The straightener body is sleeved on the lower part of the upper connector and has a clearance fit with the outer surface of the lower connector.

7. The device for repairing and reinforcing horizontal wells with a small casing as described in claim 6, characterized in that, The upper connector is a tubular structure with a stepped outer surface that is wider at the top and narrower at the bottom. The upper end of the upper connector has an internal thread for connecting to the locking mechanism, and the lower end of the upper connector has an external thread for connecting to the external thread on the upper end of the lower connector. The outer surface of the lower connector is a stepped surface that is wider at the top and narrower at the bottom, and the lower end of the lower connector has an external thread for connecting to the sealing device.

8. The device for repairing and reinforcing horizontal wells with a small casing as described in claim 7, characterized in that, The straightening body is cylindrical and its diameter is slightly larger than the outer diameter of the other components of the sealing device. A set of inclined grooves at an angle to its center line are uniformly arranged on the outer surface of the straightening body.

9. The device for repairing and reinforcing horizontal wells with a small casing as described in claim 8, characterized in that, The sealing device is a drillable ball seat, which has the same structure as the drillable floating hoop.

10. The device for repairing and reinforcing horizontal wells with a small casing as described in claim 1, characterized in that, The differential pressure sleeve and the drillable float are connected by a threaded connection.

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