Small-diameter bridge plug operation method

Abstract

The invention relates to the technical field of petroleum and shale gas exploitation, and particularly discloses a small-diameter bridge plug operation method which comprises the following steps: S1, acquiring the inner diameters of all casing change points on a plugging position path from a bridge plug to an oil casing, recording the inner diameter of each casing change point, and screening out the casing change point with the minimum inner diameter; s2, analyzing the deformation condition of the sleeve deformation point with the minimum inner diameter based on an image recognition method, wherein the deformation condition comprises the maximum deformation position of the sleeve deformation point and the corresponding deformation amount; s3, selecting a small-diameter bridge plug with a proper size based on the inner diameter of the maximum deformation position; s4, the size of the cutting sleeve is determined based on the conventional inner diameter of the oil casing, the inner diameter of the oil casing at the maximum deformation position and the diameter of the small-diameter bridge plug; s5, the clamping sleeve is arranged on the small-diameter bridge plug in a sleeving mode, and assembling is completed; and S6, the small-diameter bridge plug is fed into the plugging position in the oil casing. The small-diameter bridge plug can smoothly pass through the sleeve change point, and the plugging effect of the small-diameter bridge plug is not affected as far as possible.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum and shale gas exploitation, and in particular to a small-diameter bridge plug operation method. Background Art

[0002] Horizontal well staged fracturing technology is a common technology for the development of unconventional energy sources such as tight gas, tight oil and shale gas. Bridge plugs are important downhole staged temporary plugging tools in the current horizontal well volume fracturing process. All materials used to prepare bridge plugs are required to have certain strength, ductility and solubility.

[0003] During the fracturing process of shale, the formation is deformed due to fracturing, and thus the bottom piled wellbore pipe is deformed and its diameter becomes smaller. In the subsequent bridge plug pumping process, the wellbore diameter becomes smaller, which affects the passage of the normal-sized bridge plug, the sealing tool and the tool string, so that the bridge plug cannot smoothly reach the fracturing part of the shale layer.

[0004] Therefore, a small-diameter bridge plug (with a diameter less than or equal to 70 mm) is designed for casing change wells. The small-diameter bridge plug can smoothly pass through the casing change point by utilizing its small diameter. However, there is the following problem: when the deformation at the casing change point is large, in order to make the bridge plug pass through the casing change point smoothly, a relatively small-diameter bridge plug is required. However, due to the relatively large difference between the small-diameter bridge plug and the inner diameter of the oil casing, the plugging effect of the small-diameter bridge plug is affected. Summary of the invention

[0005] The object of the present invention is to provide a small-diameter bridge plug operation method, which can enable the small-diameter bridge plug to pass through the sleeve change point smoothly and can minimize the impact on the plugging effect of the small-diameter bridge plug.

[0006] The present invention is achieved through the following technical solutions:

[0007] A small diameter bridge plug operation method comprises the following steps:

[0008] S1. Obtain the inner diameters of all the casing change points on the path where the bridge plug reaches the plugging position in the oil casing, and record the inner diameters of each casing change point. Based on the inner diameter of the oil casing, select the casing change point with the smallest inner diameter (maximum deformation);

[0009] S2. Analyze the deformation of the sleeve change point with the smallest inner diameter based on an image recognition method, wherein the deformation includes the maximum deformation position of the sleeve change point and the corresponding deformation amount;

[0010] S3, selecting a small-diameter bridge plug of appropriate size based on the inner diameter of the maximum deformation position, wherein the diameter of the selected small-diameter bridge plug is smaller than the inner diameter of the maximum deformation position;

[0011] S4, determining the size of the ferrule based on the conventional inner diameter of the oil casing and the inner diameter of the oil casing at the maximum deformation position, and the diameter of the small-diameter bridge plug;

[0012] S5. Put the ferrule on the small diameter bridge plug to complete the assembly;

[0013] S6. Send a small diameter bridge plug into the plugging position in the oil casing.

[0014] The deformation of the ferrule described in the present invention enables the small-diameter bridge plug with the ferrule to smoothly pass through the ferrule change point with the largest deformation. The maximum outer diameter of the small-diameter bridge plug with the ferrule is larger than the inner diameter of the oil casing at the maximum deformation position, and smaller than the conventional inner diameter of the oil casing.

[0015] The present invention obtains the sleeve change point of the oil casing first, analyzes the deformation of the sleeve change point with the largest deformation amount, selects a small-diameter bridge plug of appropriate size according to the analysis result, and uses a ferrule matched with the small-diameter bridge plug, so that the small-diameter bridge plug with the ferrule has an outer diameter larger than the minimum size of the sleeve change point, and the deformation amount of the ferrule can enable the small-diameter bridge plug with the ferrule to smoothly pass through the sleeve change point with the largest deformation amount. Moreover, since the maximum outer diameter of the small-diameter bridge with the ferrule is larger than the inner diameter of the oil casing at the maximum deformation position, and smaller than the conventional inner diameter of the oil casing, the present invention can not only enable the relatively large-sized small-diameter bridge plug with the ferrule to smoothly pass through the sleeve change point with the largest deformation amount, but also reduce the gap between the small-diameter bridge plug and the oil casing as much as possible, thereby reducing the problem of poor plugging effect caused by the small-diameter bridge plug or the problem of complicated plugging operation due to the size of the small-diameter bridge plug.

[0016] Furthermore, in step S1, the MIT24 multi-arm caliper logging tool is used to enter the well on site to measure the inner diameters of all casing change points on the path where the bridge plug reaches the plugging position, and the inner diameters of each casing change point are recorded. The MIT24 multi-arm caliper logging tool is a prior art.

[0017] Furthermore, in step S2, the maximum deformation position is determined based on the oil casing, and the determination process is: the oil casing is divided into four quadrants according to the diameter of the oil casing perpendicular to the ground and the diameter parallel to the ground, and based on the divided quadrants, it is determined in which quadrant the maximum deformation position specifically falls.

[0018] Further, in step S4, the size of the ferrule includes the outer diameter and inner diameter of the ferrule, the inner diameter of the ferrule is equal to the diameter of the small diameter bridge plug, the outer diameter of the ferrule is smaller than the inner diameter of the oil casing, and the outer diameter of the ferrule is larger than the minimum inner diameter at the sleeve deformation point, and the ferrule passes through the maximum deformation position in the oil casing through the deformation of the ferrule.

[0019] Furthermore, in step S4, an easily deformable area matching the maximum deformation position is provided on the ferrule. When the small diameter bridge plug passes through the sleeve change point, the easily deformable area is deformed under the extrusion of the maximum deformation position to ensure that the small diameter bridge plug passes smoothly through the sleeve change point with the minimum diameter.

[0020] Furthermore, in step S4, the material of the ferrule is soluble rubber; the easily deformable area uses softer and more easily deformable soluble rubber.

[0021] Further, in step S4, a buffer groove is provided on the inner wall of the easily deformable zone, and both ends of the inner wall of the easily deformable zone extend outward along the circumferential direction to form an extension section; an extension accommodating groove is provided in the ferrule to accommodate the extension section, and when the easily deformable zone is not squeezed, the extension section does not fill the extension accommodating groove.

[0022] Furthermore, the buffer groove is a V-shaped groove or an arc-shaped groove.

[0023] Furthermore, in step S4, the easily deformable area is arranged on the ferrule in a nested manner.

[0024] Furthermore, the specific process of step S6 is:

[0025] Based on the quadrant method used to determine the maximum deformation position in step S2, the ferrule on the small-diameter bridge plug is divided into areas in the same way. When the small-diameter bridge plug enters the horizontal section of the casing, the quadrant area where the easy-to-deform area is located and the area where the maximum deformation position is located are placed in a way that the two overlap in the axial direction of the casing. The small-diameter bridge plug is sent to the sleeve change point through the input tool. Under the action of the easy-to-deform area, the small-diameter bridge plug passes through the sleeve change point smoothly and finally reaches the plugging position.

[0026] Furthermore, in step S4, a plurality of ferrules are sleeved on the small-diameter bridge plug, and the easily deformable areas on the plurality of ferrules are on the same axis.

[0027] Furthermore, among the plurality of ferrules, there is a certain annular gap between two adjacent ferrules to accommodate the deformation amount of the ferrules when they are deformed.

[0028] Furthermore, the end of the ferrule located at the front end of the small-diameter bridge plug extends radially inward to form a protection ring, and the protection ring is located at the end of the front end of the small-diameter bridge plug.

[0029] Furthermore, in step S1, the inner diameters of all sleeve change points on the path where the bridge plug reaches the plugging position are sorted in descending order, and the difference in the inner diameters of two adjacent sleeve change points in the sorting is calculated for subsequent determination of the material and size of the ferrule. By determining the size and material of the ferrule, the ferrule is allowed to arrange the second sleeve change point through the deformation amount under the action of its own deformation.

[0030] Further, in step S1, the outer wall of the ferrule is a spiral structure, a sawtooth structure or a wavy structure.

[0031] Further, in step S1, the inner wall of the ferrule is provided with protrusions, threads or grid patterns.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0033] 1. The present invention obtains the sleeve change point of the oil casing and analyzes the deformation of the sleeve change point with the largest deformation, selects a small-diameter bridge plug of appropriate size according to the analysis result, and sets a clamping sleeve matched with the small-diameter bridge plug; the small-diameter bridge plug with the clamping sleeve can smoothly pass through the sleeve change point with the largest deformation, and the gap between the small-diameter bridge plug and the oil casing can be reduced as much as possible, thereby reducing the problem of poor plugging effect caused by the small-diameter bridge plug or the problem of complicated plugging operation due to the size of the small-diameter bridge plug.

[0034] 2. The present invention sets an easy-deformation zone on the ferrule. Since the easy-deformation zone adopts a soluble rubber that is softer and easier to deform (relative to the ferrule), the ferrule can more easily pass through the ferrule change point with the largest deformation. Moreover, through the set easy-deformation zone, a small-diameter bridge plug with a larger ferrule can smoothly pass through the ferrule change point with the largest deformation, and the gap between the bridge plug and the oil casing can be reduced as much as possible, thereby reducing the problem of poor sealing effect caused by the small-diameter bridge plug or the problem of complicated sealing operation due to the size of the small-diameter bridge plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0036] Figure 1 The schematic diagram of the present invention is that the oil casing is divided into four quadrants, wherein a, b, c and d are four quadrants respectively;

[0037] Figure 2 It is a schematic diagram of the inner sleeve change point of the oil casing of the present invention;

[0038] Figure 3 It is a schematic diagram of the ferrule being sleeved on the small-diameter bridge plug when the easy-to-deform zone of the present invention is not deformed;

[0039] Figure 4 It is a schematic diagram of the ferrule being sleeved on the small diameter bridge plug when the easy deformation zone is deformed according to the present invention.

[0040] Marks and corresponding parts names in the attached drawings:

[0041] 1-ferrule; 2-extension accommodating groove; 3-easy deformation area; 4-buffer groove; 5-extension section; 100-oil casing; 101-maximum deformation position; 200-small diameter bridge plug. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0043] Embodiment 1:

[0044] A small diameter bridge plug operation method comprises the following steps:

[0045] S1. Use the MIT24 multi-arm caliper logging tool to enter the well, measure the inner diameters of all casing change points on the path where the bridge plug reaches the plugging position in the oil casing 100, and record the inner diameters of each casing change point. Based on the inner diameter of the oil casing 100, select the casing change point with the smallest inner diameter (maximum deformation).

[0046] S2. Analyze the deformation of the sleeve change point with the smallest inner diameter based on the image recognition method. The deformation includes the maximum deformation position 101 of the sleeve change point and the corresponding deformation amount. The image recognition method used to analyze the deformation at the sleeve change point with the smallest inner diameter is a prior art, and the deformation amount can be directly calculated by the image recognition method.

[0047] The maximum deformation position 101 is determined based on the oil casing 100. The determination process is as follows: the oil casing 100 is divided into four quadrants according to the diameter of the oil casing 100 perpendicular to the ground and the diameter parallel to the ground. Figure 1 As shown, based on the divided quadrants, it is determined in which quadrant the maximum deformation position 101 specifically falls.

[0048] Among them, the sleeve deformation point with the smallest inner diameter (maximum deformation) is as follows Figure 2 As shown, the deformation amount is the radial distance between the highest point of the maximum deformation position 101 and the inner wall of the oil casing 100.

[0049] S3. Select a small-diameter bridge plug 200 of appropriate size based on the inner diameter of the maximum deformation position 101 , wherein the diameter of the selected small-diameter bridge plug 200 is smaller than the inner diameter of the maximum deformation position 101 .

[0050] S4. Determine the size and material of the ferrule 1 based on the conventional inner diameter of the oil casing 100, the inner diameter of the oil casing 100 at the maximum deformation position 101, and the diameter of the small-diameter bridge plug 200:

[0051] Among them, the material of the ferrule 1 is soluble rubber. When in use, the ferrule 1 is sleeved on the outer wall of the small-diameter bridge 200 to increase the diameter of the small-diameter bridge plug 200 sleeved with the ferrule 1, so as to reduce the size difference between the diameter of the small-diameter bridge plug 200 and the inner diameter of the oil casing 100.

[0052] Among them, the size of the ferrule 1 includes the outer diameter and inner diameter of the ferrule 1. The inner diameter of the ferrule 1 is equal to the diameter of the small diameter bridge plug 200, so that the ferrule 1 can be sleeved on the small diameter bridge plug 200. The outer diameter of the ferrule 1 is smaller than the inner diameter of the oil casing 100, and the outer diameter of the ferrule 1 is larger than the minimum inner diameter at the sleeve change point.

[0053] Preferably, an easy-to-deform zone 3 matching the maximum deformation position 101 is provided on the ferrule 1. Specifically, the easy-to-deform zone 3 is arranged on the ferrule 1 in a nested manner. When the small-diameter bridge plug 200 passes through the sleeve change point, the easy-to-deform zone 3 is deformed under the extrusion of the maximum deformation position 101 to ensure that the small-diameter bridge plug 200 smoothly passes through the sleeve change point with the smallest diameter.

[0054] The material of the ferrule 1 is soluble rubber; the easily deformable zone 3 uses a soluble rubber that is softer and more easily deformed than the ferrule 1; the soluble rubber used in the ferrule 1 and the easily deformable zone 3 are both existing technical materials.

[0055] Specifically, the inner wall of the easy-to-deform zone 3 is provided with a buffer groove 4, and the two ends of the inner wall of the easy-to-deform zone 3 extend outward along the circumferential direction to form an extension section 5; the ferrule 1 is provided with an extension accommodating groove 2 for accommodating the extension section 5, and when the easy-to-deform zone 3 is not squeezed, the extension section 5 does not fill the extension accommodating groove 2. Preferably, the buffer groove 4 is a V-shaped groove or an arc groove.

[0056] Specifically, Figure 3 , Figure 4 As shown ( Figure 3 This is a schematic diagram of the ferrule when the easy-to-deform area is not deformed; Figure 4 is a schematic diagram of the ferrule when the easily deformable zone is deformed), the inner wall of the easily deformable zone 3 is provided with a buffer groove 4, and both ends of the inner wall of the easily deformable zone 3 extend into the ferrule 1, when the easily deformable zone 3 is squeezed, the easily deformable zone 3 is compressed and deformed, so that the small diameter bridge plug 200 can smoothly pass through the maximum deformation position 101, after the small diameter bridge plug 200 passes through the maximum deformation position 101, the easily deformable zone 3 can restore to its original position, even if the easily deformable zone 3 cannot return to its original position due to excessive squeezing, it will not affect the blocking effect of the small diameter bridge plug 200 on the blocking position of the oil casing 100; since the easily deformable zone 3 is only a part of the ferrule 1, it does not affect the effect of the ferrule 1 on reducing the gap between the small diameter bridge plug 200 and the oil casing 100.

[0057] S5, sleeve the ferrule 1 on the small-diameter bridge plug 200 to complete the assembly; the deformation of the ferrule 1 can enable the small-diameter bridge plug 200 sleeved with the ferrule 1 to smoothly pass through the sleeve change point with the largest deformation, and the maximum outer diameter of the small-diameter bridge plug 200 sleeved with the ferrule 1 is greater than the inner diameter of the oil casing 100 at the maximum deformation position 101, and is smaller than the conventional inner diameter of the oil casing 100. When the ferrule 1 is embedded with the easy-deformation zone 3, the deformation of the easy-deformation zone 3 can enable the small-diameter bridge plug 200 sleeved with the ferrule 1 to smoothly pass through the sleeve change point with the largest deformation.

[0058] S6. Send the small-diameter bridge plug 200 into the plugging position in the oil casing 100:

[0059] Based on the quadrant method used to determine the maximum deformation position 101 in step S2, the ferrule 1 on the small-diameter bridge plug 200 is divided into areas in the same manner, and the quadrant area where the easy-deformation zone 3 is located and the area where the maximum deformation position 101 is located are placed in such a way that the two overlap in the axial direction of the oil casing 100 when the small-diameter bridge plug 200 enters the horizontal section of the oil casing 100. The small-diameter bridge plug 200 is sent into the sleeve change point by an input tool, and under the action of the easy-deformation zone 3, the small-diameter bridge plug 200 smoothly passes through the sleeve change point and finally reaches the plugging position.

[0060] In a specific case, in step S4, a plurality of ferrules 1 are sleeved on the small-diameter bridge plug 200, and the easily deformable areas 3 on the plurality of ferrules 1 are on the same axis. Among the plurality of ferrules 1, there is a certain annular gap between two adjacent ferrules 1 to accommodate the deformation amount of the ferrules 1 when they are deformed.

[0061] In a preferred case, the end of the ferrule 1 at the front end of the small-diameter bridge plug 200 extends radially inward to form a protection ring, which is located at the front end of the small-diameter bridge plug 200. On the one hand, it can be used to protect the small-diameter bridge plug 200, and on the other hand, it can prevent the ferrule 1 at the front end of the small-diameter bridge plug 200 from being relatively displaced with the small-diameter bridge plug 200 when the axial thrust is applied.

[0062] In a preferred case, in step S1, the inner diameters of all sleeve change points on the path where the bridge plug reaches the blocking position are sorted in descending order, and the difference in the inner diameters of two adjacent sleeve change points in the sorting is calculated for subsequent determination of the material and size of the ferrule 1. By determining the size and material of the ferrule 1, the ferrule 1 arranges the second sleeve change point through the deformation amount under the action of its own deformation, thereby ensuring that the small-diameter bridge plug 200 with the ferrule 1 can smoothly pass through all the sleeve change points to reach the blocking area.

[0063] In a preferred case, the outer wall of the ferrule 1 is a spiral structure, a sawtooth structure or a wavy structure.

[0064] In a preferred case, in step S1 , the inner wall of the ferrule 1 is provided with protrusions, threads or grid patterns to increase the friction between the ferrule 1 and the small-diameter bridge plug 200 .

[0065] In summary, in this embodiment, the sleeve change point of the oil casing 100 is first obtained, and the deformation of the sleeve change point with the largest deformation is analyzed. According to the analysis result, a small-diameter bridge plug 200 of appropriate size is selected, and a ferrule 1 matched with the small-diameter bridge plug 200 is provided, so that the small-diameter bridge plug 200 with the ferrule 1 has an outer diameter greater than the minimum size of the sleeve change point, and through the provided easy-to-deform zone 3, the small-diameter bridge plug 200 with a larger size and provided with the ferrule 1 can smoothly pass through the sleeve change point with the largest deformation, and the gap between the small-diameter bridge plug 200 and the oil casing 100 can be reduced as much as possible, thereby reducing the problem of poor plugging effect caused by the small-diameter bridge plug 200 or the problem of complicated plugging operation due to the size of the small-diameter bridge plug 200.

[0066] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0067] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and the like cited in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of the relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

Claims

1. A small diameter bridge plug operation method, It is characterized in that The following steps are involved: S1, obtaining the inner diameters of all casing change points on the path where the bridge plug reaches the plugging position in the oil casing (100), recording the inner diameters of each casing change point, and selecting the casing change point with the smallest inner diameter based on the inner diameter of the oil casing (100); S2, analyzing the deformation of the sleeve change point with the smallest inner diameter based on an image recognition method, wherein the deformation includes the maximum deformation position (101) of the sleeve change point and the corresponding deformation amount; S3, selecting a small-diameter bridge plug (200) of appropriate size based on the inner diameter of the maximum deformation position (101), wherein the diameter of the selected small-diameter bridge plug (200) is smaller than the inner diameter of the maximum deformation position (101); S4, determining the size of the ferrule (1) based on the conventional inner diameter of the oil casing (100), the inner diameter of the oil casing (100) at the maximum deformation position (101), and the diameter of the small-diameter bridge plug (200); S5, sleeve the ferrule (1) onto the small-diameter bridge plug (200) to complete the assembly; S6. Send a small-diameter bridge plug (200) into the oil casing (100) to seal the position.

2. A small diameter bridge plug operation method according to claim 1, It is characterized in that In step S1, an MIT24 multi-arm caliper logging tool is used to enter the well on site to measure the inner diameters of all casing change points on the path where the bridge plug reaches the plugging position, and the inner diameter of each casing change point is recorded.

3. A small diameter bridge plug operation method according to claim 1, It is characterized in that In step S2, the maximum deformation position (101) is determined based on the oil casing (100), and the determination process is: the oil casing (100) is divided into four quadrants according to the diameter of the oil casing (100) perpendicular to the ground and the diameter parallel to the ground, and based on the divided quadrants, it is determined in which quadrant the maximum deformation position (101) specifically falls.

4. A small diameter bridge plug operation method according to claim 1, It is characterized in that In step S4, the size of the ferrule (1) includes the outer diameter and inner diameter of the ferrule (1), the inner diameter of the ferrule (1) is equal to the diameter of the small-diameter bridge plug (200), the outer diameter of the ferrule (1) is smaller than the inner diameter of the oil casing (100), and the outer diameter of the ferrule (1) is larger than the minimum inner diameter at the sleeve deformation point, and the ferrule (1) passes through the maximum deformation position (101) in the oil casing (100) through deformation.

5. A small diameter bridge plug operation method according to claim 1, It is characterized in that In step S4, an easily deformable area (3) matching the maximum deformation position (101) is provided on the ferrule (1). When the small-diameter bridge plug (200) passes through the sleeve deformation point, the easily deformable area (3) is deformed under the pressure of the maximum deformation position (101) to ensure that the small-diameter bridge plug (200) passes smoothly through the sleeve deformation point with the minimum diameter.

6. A small diameter bridge plug operation method according to claim 5, It is characterized in that In step S4, the material of the ferrule (1) is soluble rubber; the easily deformable area (3) is made of soluble rubber that is softer and more easily deformed.

7. A small diameter bridge plug operation method according to claim 5, It is characterized in that In step S4, a buffer groove (4) is provided on the inner wall of the easily deformable zone (3), and both ends of the inner wall of the easily deformable zone (3) extend outward along the circumferential direction to form an extension section (5); an extension accommodating groove (2) for accommodating the extension section (5) is provided in the ferrule (1), and when the easily deformable zone (3) is not squeezed, the extension section (5) does not fill the extension accommodating groove (2).

8. A small diameter bridge plug operation method according to claim 7, It is characterized in that The buffer groove (4) is a V-shaped groove or an arc-shaped groove.

9. A small diameter bridge plug operation method according to claim 5, It is characterized in that In step S4, the easily deformable area (3) is arranged on the ferrule (1) in a nested manner.

10. A small diameter bridge plug operation method according to claim 5, It is characterized in that The specific process of step S6 is: Based on the quadrant method used to determine the maximum deformation position (101) in step S2, the ferrule (1) on the small-diameter bridge plug (200) is divided into regions in the same manner, and the quadrant region where the easy-to-deform zone (3) is located and the region where the maximum deformation position (101) is located are arranged such that the small-diameter bridge plug (200) overlaps in the axial direction of the oil casing (100) when the small-diameter bridge plug (200) enters the horizontal section of the oil casing (100). The small-diameter bridge plug (200) is sent to the sleeve change point by an input tool, and under the action of the easy-to-deform zone (3), the small-diameter bridge plug (200) smoothly passes through the sleeve change point and finally reaches the plugging position.

11. A small diameter bridge plug operation method according to claim 5, It is characterized in that In step S4, a plurality of ferrules (1) are sleeved on the small-diameter bridge plug (200), and the easily deformable areas (3) on the plurality of ferrules (1) are on the same axis.

12. A small diameter bridge plug operation method according to claim 11, It is characterized in that Among the plurality of ferrules (1), a certain annular gap is provided between two adjacent ferrules (1) for accommodating the deformation amount of the ferrules (1) when they are deformed.

13. A small diameter bridge plug operation method according to claim 11, It is characterized in that The end of the ferrule (1) located at the front end of the small-diameter bridge plug (200) extends radially inward to form a protection ring, and the protection ring is located at the front end of the small-diameter bridge plug (200).

14. A small diameter bridge plug operation method according to claim 5, It is characterized in that In step S1, the inner diameters of all sleeve change points on the path of the bridge plug to the plugging position are sorted in descending order, and the difference in the inner diameters of two adjacent sleeve change points in the sorting is calculated for use in the subsequent determination of the material and size of the ferrule (1). By determining the size and material of the ferrule (1), the ferrule (1) is arranged to have a second sleeve change point through the deformation amount under the action of its own deformation.

15. A small diameter bridge plug operation method according to any one of claims 1 to 14, It is characterized in that In step S1, the outer wall of the ferrule (1) is a spiral structure, a sawtooth structure or a wavy structure.

16. A small diameter bridge plug operation method according to any one of claims 1 to 14, It is characterized in that In step S1, the inner wall of the ferrule (1) is provided with protrusions, threads or grid patterns.

Images