Differential pressure sliding sleeve and pressure testing method

Abstract

The invention belongs to the technical field of downhole tools, and particularly relates to a differential pressure sliding sleeve and a pressure testing method. The differential pressure sliding sleeve comprises an outer cylinder, an inner cylinder and an inner cylinder, wherein a flow guide hole is formed in the outer cylinder; the differential pressure cylinder is arranged in the outer cylinder through a first pin and is used for blocking the flow guide hole; the at least one locking cylinder is arranged in the outer cylinder through a second pin, the locking cylinders are arranged at the downstream of the differential pressure cylinder at intervals, and the pressure critical value of the locking cylinders is smaller than the starting pressure value of the first pin. The pressure integrity testing device can meet the requirement for pressure integrity testing of the whole shaft casing pipe.

Description

Technical Field

[0001] This invention belongs to the field of downhole tool technology, specifically relating to a differential pressure sliding sleeve and a method for testing the differential pressure sliding sleeve. Background Technology

[0002] With the development of unconventional oil and gas resources, horizontal well staged fracturing technology has become one of the most effective means of developing unconventional oil and gas reservoirs.

[0003] Currently, by pre-installing a sliding sleeve at the toe of a horizontal well, fracturing can be performed directly by pressurizing the tubing and opening the sliding sleeve during fracturing operations, which can greatly reduce the cost of the first stage of fracturing.

[0004] However, before fracturing, a pressure integrity test must be performed on the entire well casing to ensure the smooth implementation of subsequent operations. Conventional sliding sleeves cannot meet this requirement. Conventional sliding sleeves will open once subjected to pressure exceeding the predetermined pressure value, thus limiting the pressure test intensity and frequently resulting in accidental opening of the sliding sleeve.

[0005] Therefore, there is an urgent need to develop a sliding sleeve that can meet the requirements for pressure integrity testing of the entire well casing. Summary of the Invention

[0006] To address the technical problems described above, this invention aims to provide a differential pressure sliding sleeve that can meet the requirements for pressure integrity testing of the entire well casing.

[0007] This invention also proposes a pressure testing method that uses the differential pressure sliding sleeve proposed in this invention, which can meet the requirements for pressure integrity testing of the entire well casing.

[0008] According to the present invention, a differential pressure sleeve is provided, comprising:

[0009] The outer cylinder has flow guide holes.

[0010] A differential pressure cylinder that seals the guide hole by means of a first pin located inside the outer cylinder; and

[0011] At least one locking cylinder is installed inside the outer cylinder by a second pin, the locking cylinders being spaced out downstream of the differential pressure cylinder, and the pressure threshold of the locking cylinder being less than the starting pressure of the first pin.

[0012] In one specific embodiment, the axial distance between the locking cylinder and the differential pressure cylinder is not less than the diameter of the first pin, and the axial distance between two adjacent locking cylinders is not less than the diameter of the second pin.

[0013] In one specific embodiment, the pressure threshold of each of the locking cylinders gradually decreases from upstream to downstream.

[0014] In one specific embodiment, a fifth seal is provided between the second pin and the outer cylinder.

[0015] In one specific embodiment, the outer cylinder includes a first cylinder section and a second cylinder section, wherein the inner diameter of the first cylinder section is larger than the inner diameter of the second cylinder section;

[0016] The differential pressure cylinder includes a third cylinder section and a fourth cylinder section. The outer diameter of the third cylinder section is larger than the outer diameter of the fourth cylinder section. A first sealing element and a second sealing element are provided between the third cylinder section and the outer cylinder. The first sealing element and the second sealing element are respectively located on the upper and lower sides of the flow guide hole.

[0017] The locking cylinder includes a fifth cylinder section and a sixth cylinder section. The outer diameter of the fifth cylinder section is larger than that of the sixth cylinder section. The fifth cylinder section is disposed between the fourth cylinder section and the outer cylinder. A third sealing element is disposed between the fifth cylinder section and the fourth cylinder section. The sixth cylinder section is located inside the second cylinder section. A fourth sealing element is disposed between the sixth cylinder section and the second cylinder section.

[0018] In one specific embodiment, the axial clearance between the third cylinder section and the fifth cylinder section is not less than the diameter of the first pin.

[0019] In one specific embodiment, the axial distance from the first seal to the upper end of the guide hole is d1, the axial interval between the locking cylinder and the differential pressure cylinder is d2, the axial interval between two adjacent locking cylinders is d3, and d1≥d2+d3.

[0020] In one specific embodiment, the axial distance between the downstream locking cylinder and the second cylinder section is d4, d1. <d2+d3+d4。

[0021] According to the present invention, a pressure testing method using a differential pressure sleeve provided according to the present invention is also provided, comprising the following steps:

[0022] S1. Pressurize the differential pressure sleeve until the pressure exceeds the starting pressure value of the first pin, thereby causing the differential pressure cylinder to move downward relative to the outer cylinder until it axially abuts against the locking cylinder;

[0023] S2. Test the differential pressure sleeve within a pressure range greater than the critical pressure value of the locking cylinder.

[0024] In one specific embodiment, the differential pressure sleeve includes a multi-stage locking cylinder, characterized by further including the following steps:

[0025] S3. Control the pressure between the critical pressure values ​​of the first-stage locking cylinder and the second-stage locking cylinder, and the differential pressure cylinder pushes the first-stage locking cylinder to move until it axially abuts against the second-stage locking cylinder;

[0026] S4. Test the differential pressure sleeve within a pressure range greater than the pressure critical value of the secondary locking cylinder;

[0027] S5. Following steps S3 and S4, gradually reduce the pressure to test the differential pressure sleeve.

[0028] Compared with the prior art, the advantages of this application are as follows.

[0029] This invention includes an outer cylinder and a differential pressure cylinder and a locking cylinder disposed within the outer cylinder. The differential pressure cylinder is constructed to have a differential pressure surface, and when subjected to pressure, it can move axially relative to the outer cylinder and axially abut against the locking cylinder. The locking cylinder does not have a differential pressure surface; that is, the force-bearing surfaces at its upper and lower ends are equal in area. When the locking cylinder is subjected to pressure, it deforms and expands radially, increasing the friction between the outer wall of the locking cylinder and the inner wall of the outer cylinder. When this pressure increases to a certain value, the force exerted by the differential pressure on the differential pressure cylinder to move axially downward is insufficient to push the locking cylinder to move axially relative to the outer cylinder. Furthermore, as long as the pressure exceeds this certain value, the locking cylinder cannot move axially relative to the outer cylinder, thus preventing the differential pressure cylinder from moving relative to the outer cylinder to open the guide hole. This is because the increase in frictional resistance after the outer cylinder and the locking cylinder are in contact is much greater than the increase in the axial thrust experienced by the differential pressure cylinder. This application describes this specific pressure value as a critical pressure value.

[0030] The critical pressure value of the locking cylinder is less than the starting pressure value of the first pin. When it is necessary to test the differential pressure sleeve, pressure is applied to the differential pressure sleeve. When the pressure increases to exceed the starting pressure value of the first pin, the differential pressure cylinder moves axially relative to the outer cylinder and abuts against the locking cylinder axially. At this time, the differential pressure cylinder is still in a blocked state for the guide hole. Since the starting pressure value of the first pin is greater than the critical pressure value of the locking cylinder, the differential pressure cylinder cannot continue to move after abutting against the locking cylinder. After that, pressure can continue to be applied for testing. The guide hole will not open accidentally due to the increase in pressure, thus meeting the requirements for the pressure integrity test of the entire wellbore. Attached Figure Description

[0031] The invention will now be described with reference to the accompanying drawings.

[0032] Figure 1 A schematic diagram showing a differential pressure sleeve with a locking cylinder according to the present invention is shown;

[0033] Figure 2 A schematic diagram showing the differential pressure sleeve with two locking cylinders according to the present invention is provided;

[0034] Figures 3-5 Showing Figure 2 The diagram shown illustrates the working principle of the differential pressure sleeve undergoing multiple pressure tests.

[0035] Figure 6 A schematic diagram showing a differential pressure sleeve with multiple locking cylinders according to the present invention is shown.

[0036] In the picture:

[0037] 1. Outer cylinder; 11. Flow guide hole; 12. First cylinder section; 13. Second cylinder section; 2. Differential pressure cylinder; 21. Third cylinder section; 22. Fourth cylinder section; 3. Locking cylinder; 31. Fifth cylinder section; 32. Sixth cylinder section; 33. Seventh cylinder section; 41. Upper connector; 42. Lower connector; 81. First seal; 82. Second seal; 83. Third seal; 84. Fourth seal; 85. Fifth seal; 86. Sixth seal; 87. Seventh seal; 88. Eighth seal; 91. First pin; 92. Second pin; 100. Differential pressure sliding sleeve.

[0038] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0039] The invention will now be described with reference to the accompanying drawings.

[0040] It should be noted that the direction near the wellhead after the differential pressure sliding sleeve of the present invention is inserted into the well is described as "upstream", "front end" or similar terms, i.e. Figure 1 Above; the direction away from the wellhead after the differential pressure sliding sleeve is inserted into the well is described as "downstream," "rear end," or similar terms, i.e. Figure 1 Below.

[0041] In this application, the differential pressure sliding sleeve provided by the present invention is not limited to use in horizontal wells, but can also be used in vertical wells, inclined wells and other working conditions.

[0042] Example 1:

[0043] Figure 1 The structure of the differential pressure sleeve 100 according to the present invention is shown. For example... Figure 1 As shown, the differential pressure sleeve 100 includes an outer cylinder 1, a differential pressure cylinder 2, and a locking cylinder 3.

[0044] The outer cylinder 1 is generally cylindrical in shape, and at least one flow guide hole 11 is provided on the cylinder wall of the outer cylinder 1, which connects the inner cavity of the outer cylinder 1 to the outside. In this embodiment, multiple flow guide holes 11 are arranged at intervals along the circumferential direction on the cylinder wall of the outer cylinder 1.

[0045] The differential pressure cylinder 2 is generally cylindrical in shape. It is fixed inside the outer cylinder 1 by a first pin 91 and blocks the guide hole 11. The pressure-bearing areas at the upper and lower ends of the differential pressure cylinder 2 are different, which allows the differential pressure cylinder 2 to move axially relative to the outer cylinder 1 under the action of the pressure difference between the upper and lower ends when it is subjected to pressure.

[0046] The locking cylinder 3 is generally cylindrical in shape. It is fixed inside the outer cylinder 1 by the second pin 92 and is spaced downstream of the differential pressure cylinder 2, meaning there is an axial gap between the locking cylinder 3 and the differential pressure cylinder 2. The upper and lower ends of the locking cylinder 3 have the same pressure-bearing area, meaning that the locking cylinder 3 will not move axially on its own after being subjected to pressure.

[0047] The basic operating principle of the differential pressure sleeve 100 provided by this invention is based on the principle that the locking cylinder 3, under a certain pressure, undergoes slight elastic deformation and other stresses, resulting in radial expansion and tight contact with the inner wall of the outer cylinder 1, thus forming a lock and causing the movement to fail. In experiments, it was found that in existing technologies, the inner cylinder with the differential pressure surface of the sleeve cannot be opened due to excessive pressure; it can only be opened smoothly after the pressure is reduced. This is because the inner cavity of the inner cylinder expands radially outward under pressure, undergoing elastic deformation and contacting the outer cylinder, thereby increasing the friction between the inner and outer cylinders. This pressure causing the inner cylinder to expand radially outward has a specific value. When this specific value is exceeded, the inner cylinder cannot move axially relative to the outer cylinder even under greater force, because the increase in frictional resistance after the inner and outer cylinders are in contact is much greater than the increase in the differential pressure force on the inner cylinder. This specific value is defined and described in this invention as a critical pressure value.

[0048] Therefore, in the prior art, it is usually necessary to avoid the pressure from exceeding the pressure critical value in order to ensure that the inner cylinder with the pressure differential surface can move axially relative to the outer cylinder, thereby opening the sliding sleeve.

[0049] This application, however, utilizes this principle in reverse. In this application, the critical pressure value of the locking cylinder 3 is less than the starting pressure value of the first pin 91. The starting pressure value of the first pin 91 refers to the pressure value at which the differential pressure cylinder 2 can be sheared by the pressure difference force after being subjected to pressure.

[0050] This design allows for pressure integrity testing of the entire well casing. When the differential pressure sleeve 100 is inserted into the well along with other well casings and a pressure integrity test is required, pressure can be applied to the well casing without worrying about the differential pressure sleeve 100 accidentally opening. When the pressure inside the differential pressure sleeve 100 increases to the starting pressure value of the first pin 91, the differential pressure cylinder 2 moves downward relative to the outer cylinder 1 under the differential pressure force of its upper and lower differential pressure surfaces until the lower end of the differential pressure cylinder 2 axially abuts against the upper end of the locking cylinder 3. At this point, the starting pressure value of the first pin 91 is greater than the critical pressure value of the locking cylinder 3. After the differential pressure cylinder 2 abuts against the locking cylinder 3, it cannot move further downward, and the guide hole 11 remains within the sealing range of the differential pressure cylinder 2. Therefore, even if the pressure is further increased, the guide hole 11 will not open, thus meeting the requirements for pressure integrity testing of the entire well casing. After the pressure test (pressure integrity test of the entire well casing) is completed, the pressure inside the differential pressure sleeve 100 is reduced to below the critical pressure value of the locking cylinder 3. This allows the differential pressure cylinder 2 to push the locking cylinder 3 to move axially relative to the outer cylinder 1 under the pressure differential force, thereby enabling the differential pressure cylinder 2 to move to open the guide hole 11 and implement subsequent downhole processes.

[0051] Example 2:

[0052] According to the present invention, based on Embodiment 1, the number of locking cylinders 3 can be set to multiple. In this embodiment, as... Figure 2 As shown, a differential pressure cylinder 2 is installed inside the outer cylinder 1 via a first pin 91 to block the flow guide hole 11. Two locking cylinders 3 are also installed inside the outer cylinder 1 via two second pins 92, with the two locking cylinders 3 spaced apart downstream of the differential pressure cylinder 2. For ease of explanation, this application names each locking cylinder 3 and its corresponding second pin 92, from upstream to downstream, as first-level locking cylinder 3, second-level locking cylinder 3, first-level second pin 92, and second-level second pin 92, respectively.

[0053] Furthermore, the axial distance between the primary locking cylinder 3 and the differential pressure cylinder 2 is not less than the diameter of the first pin 91. This ensures that during the first pressure test, when the differential pressure cylinder 2 moves relative to the outer cylinder 1 to abut against the primary locking cylinder 3, it can shear off the first pin 91, preventing the differential pressure sleeve 100 from failing to open. The axial distance between two adjacent locking cylinders 3 is not less than the diameter of the second pin 92. In other words, the axial distance between the primary locking cylinder 3 and the secondary locking cylinder 3 is not less than the diameter of the second pin 92 of the primary locking cylinder 3. This ensures that during the second pressure test, when the differential pressure cylinder 2 pushes the primary locking cylinder 3 to abut against the secondary locking cylinder 3, it can shear off the second pin 92 of the primary locking cylinder 3, preventing the differential pressure sleeve 100 from failing to open.

[0054] In this embodiment, the pressure critical value of each locking cylinder 3 gradually decreases from upstream to downstream. That is, the pressure critical value of the first-stage locking cylinder 3 is greater than the pressure critical value of the second-stage locking cylinder 3. Furthermore, the pressure critical value of the differential pressure cylinder 2 is greater than the starting pressure value of the first pin 91, thereby preventing the differential pressure cylinder 2 from moving smoothly.

[0055] In one specific embodiment, the pressure values ​​in this application are arranged from largest to smallest as follows: the pressure critical value of the differential pressure cylinder 2, the starting pressure value of the first pin 91, the pressure critical value of the first-stage locking cylinder 3, the starting pressure value of the first-stage second pin 92, the pressure critical value of the second-stage locking cylinder 3, and the starting pressure value of the second-stage second pin 92.

[0056] By setting multiple locking cylinders 3, the differential pressure sleeve 100 can be pressure tested multiple times.

[0057] like Figure 3 As shown, during the first pressure test, when the pressure inside the differential pressure sleeve 100 is greater than the starting pressure value of the first pin 91, the differential pressure cylinder 2 moves downward relative to the outer cylinder 1 until it axially abuts against the first-stage locking cylinder 3, and... Figure 3 The first pin 91 shown in section A is sheared. At this time, the guide hole 11 is still within the sealing range of the differential pressure cylinder 2, so the guide hole 11 is still in the closed state. At this time, the pressure inside the differential pressure sleeve 100 is greater than the pressure critical value of the first-stage locking cylinder 3. No matter how the pressure increases, the first-stage locking cylinder 3 can prevent the differential pressure cylinder 2 from moving further downward relative to the outer cylinder 1. Therefore, the pressure can be increased for pressure testing, as long as the pressure does not exceed the material bearing limit of each part. After the pressure test is completed, the pressure is released.

[0058] After the first pressure test, a second pressure test can be conducted if needed. Figure 4 As shown, during the second pressure test, when the pressure inside the differential pressure sleeve 100 exceeds the starting pressure value of the first-stage second pin 92, the differential pressure cylinder 2 pushes the first-stage locking cylinder 3 to move axially relative to the outer cylinder 1 until it axially abuts against the second-stage locking cylinder 3, and... Figure 4 The first-stage second pin 92 shown in section B is sheared. At this time, the guide hole 11 is still within the sealing range of the differential pressure cylinder 2, so the guide hole 11 is still in the closed state. At this time, the pressure inside the differential pressure sleeve 100 is greater than the pressure critical value of the second-stage locking cylinder 3. No matter how the pressure increases, the second-stage locking cylinder 3 can prevent the differential pressure cylinder 2 and the first-stage locking cylinder 3 from moving further downward relative to the outer cylinder 1. Therefore, the pressure can be increased further for pressure testing, as long as the pressure does not exceed the material bearing limit of each part. After the pressure test is completed, the pressure is released.

[0059] After the second pressure test is completed, when it is necessary to open the differential pressure sleeve 100, pressurize the differential pressure sleeve 100, such as... Figure 5As shown, when the pressure inside the differential pressure sleeve 100 is greater than the starting pressure value of the second secondary pin 92, the differential pressure cylinder 2 pushes the first-stage locking cylinder 3 and the second-stage locking cylinder 3 to move downward relative to the outer cylinder 1, and... Figure 5 The second secondary pin 92 shown in section C is cut off. At this time, the guide hole 11 has been removed from the sealing range of the differential pressure cylinder 2, and the guide hole 11 is in the open state, thus completing the opening of the differential pressure sleeve 100.

[0060] According to a preferred embodiment of the present invention, a fifth sealing element 85 is provided between the first pin 91 and the outer cylinder 1, and between the second pin 92 and the outer cylinder 1.

[0061] According to one specific embodiment of the present invention, the outer cylinder 1 includes a first cylinder section 12 and a second cylinder section 13, wherein the first cylinder section 12 is coaxially disposed at the upper end of the second cylinder section 13. The inner diameter of the first cylinder section 12 is larger than the inner diameter of the second cylinder section 13, and the outer diameters of the two are equal.

[0062] The differential pressure cylinder 2 includes a third cylinder section 21 and a fourth cylinder section 22, with the third cylinder section 21 coaxially disposed at the upper end of the fourth cylinder section 22. The outer diameter of the third cylinder section 21 is larger than the outer diameter of the fourth cylinder section 22, while their inner diameters are equal. The differential pressure cylinder 2 is located inside the first cylinder section 12. A first sealing element 81 and a second sealing element 82 are disposed between the outer wall of the third cylinder section 21 and the outer cylinder 1, respectively located on the upper and lower sides of the guide hole 11. A first pin 91 is located below the guide hole 11, also positioned between the first sealing element 81 and the second sealing element 82.

[0063] The locking cylinder 3 includes a fifth cylinder section 31 and a sixth cylinder section 32. Furthermore, the fifth cylinder section 31 and the sixth cylinder section 32 are connected by a seventh cylinder section 33. That is, the locking cylinder 3 includes a fifth cylinder section 31, a seventh cylinder section 33 and a sixth cylinder section 32 arranged coaxially from top to bottom.

[0064] The outer diameters of the fifth cylindrical section 31 and the seventh cylindrical section 33 are equal, and the outer diameter of the fifth cylindrical section 31 is greater than the outer diameter of the sixth cylindrical section 32. The inner diameter of the sixth cylindrical section 32 is equal to the inner diameter of the seventh cylindrical section 33, and the inner diameter of the fifth cylindrical section 31 is greater than the inner diameter of the sixth cylindrical section 32.

[0065] The fifth section 31 of the first-stage locking cylinder 3 is located between the fourth section 22 and the first section 12. That is, the outer wall of the fifth section 31 is in contact with the inner wall of the outer cylinder 1, the inner wall of the fifth section 31 is in contact with the outer wall of the fourth section 22, and a third sealing element 83 is provided between the inner wall of the fifth section 31 and the outer wall of the fourth section 22.

[0066] The fifth cylinder section 31 of the secondary locking cylinder 3 is disposed between the sixth cylinder section 32 and the first cylinder section 12 of the primary locking cylinder 3, and a fourth seal 84 is provided between the fifth cylinder section 31 of the secondary locking cylinder 3 and the sixth cylinder section 32 of the primary locking cylinder 3.

[0067] The sixth cylinder section 32 of the secondary locking cylinder 3 is located within the second cylinder section 13, and a fourth seal 84 is provided between the outer wall of the sixth cylinder section 32 and the inner wall of the second cylinder section 13.

[0068] According to the present invention, the axial gap between the fourth cylinder section 22 of the differential pressure cylinder 2 and the seventh cylinder section 33 of the primary locking cylinder 3 is equal to the axial gap between the third cylinder section 21 of the differential pressure cylinder 2 and the fifth cylinder section 31 of the primary locking cylinder 3, and is not less than the diameter of the first pin 91.

[0069] According to the present invention, as Figure 2 shown, the axial distance from the first seal 81 to the upper end of the diversion hole 11 is d1. The axial spacing between the locking cylinder 3 and the differential pressure cylinder 2, that is, the axial spacing between the fourth cylinder section 22 of the differential pressure cylinder 2 and the seventh cylinder section 33 of the primary locking cylinder 3 is d2. The axial spacing between two adjacent locking cylinders 3, that is, the axial spacing between the sixth cylinder section 32 of the primary locking cylinder 3 and the seventh cylinder section 33 of the secondary locking cylinder 3 is d3. d1≥d2 + d3, thereby preventing the diversion hole 11 from being accidentally opened.

[0070] According to the present invention, the axial spacing between the lowermost locking cylinder 3 and the second cylinder section 13, that is, the axial spacing between the seventh cylinder section 33 of the secondary locking cylinder 3 and the second cylinder section 13 is d4. d1 < d2 + d3 + d4, thereby enabling the diversion hole 11 to be normally opened.

[0071] According to the present invention, there is also provided a pressure testing method using the differential pressure sliding sleeve 100 provided by the present invention, including the following steps:

[0072] S1. Pressurize the differential pressure sliding sleeve until the pressure exceeds the starting pressure value of the first pin 91, so that the differential pressure cylinder 2 moves downward relative to the outer cylinder 1 until it axially abuts against the locking cylinder 3;

[0073] S2. Perform pressure testing on the differential pressure sliding sleeve within a pressure range greater than the pressure critical value of the locking cylinder 3;

[0074] S3. Control the pressure between the pressure critical values of the primary locking cylinder and the secondary locking cylinder, and the differential pressure cylinder 2 pushes the primary locking cylinder 3 to move until it axially abuts against the secondary locking cylinder 3;

[0075] S4. Perform pressure testing on the differential pressure sliding sleeve within a pressure range greater than the pressure critical value of the secondary locking cylinder 3;

[0076] S5. Following steps S3 and S4, gradually reduce the pressure to test the differential pressure sleeve.

[0077] According to the present invention, such as Figure 6 As shown, the number of locking cylinders 3 can be set to multiple based on the number of pressure tests.

[0078] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0079] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0080] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0081] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A differential pressure sliding sleeve, characterized in that, include: The outer cylinder (1) is provided with a flow guide hole (11); A differential pressure cylinder (2) that blocks the flow guide hole (11) is installed inside the outer cylinder (1) by a first pin (91); as well as At least one locking cylinder (3) is provided in the outer cylinder (1) by a second pin (92), the locking cylinder (3) is provided intermittently downstream of the differential pressure cylinder (2), and the pressure critical value of the locking cylinder (3) is less than the starting pressure value of the first pin (91).

2. The differential pressure sliding sleeve according to claim 1, characterized in that, The axial distance between the locking cylinder (3) and the differential pressure cylinder (2) is not less than the diameter of the first pin (91), and the axial distance between two adjacent locking cylinders (3) is not less than the diameter of the second pin (92).

3. The differential pressure sliding sleeve according to claim 1, characterized in that, The pressure threshold of each locking cylinder (3) gradually decreases from upstream to downstream.

4. The differential pressure sliding sleeve according to claim 1, characterized in that, A fifth seal (85) is provided between the second pin (92) and the outer cylinder (1).

5. The differential pressure sleeve according to any one of claims 1 to 4, characterized in that, The outer cylinder (1) includes a first cylinder section (12) and a second cylinder section (13), wherein the inner diameter of the first cylinder section (12) is larger than the inner diameter of the second cylinder section (13); The differential pressure cylinder (2) includes a third cylinder section (21) and a fourth cylinder section (22). The outer diameter of the third cylinder section (21) is larger than the outer diameter of the fourth cylinder section (22). A first sealing element (81) and a second sealing element (82) are provided between the third cylinder section (21) and the outer cylinder (1). The first sealing element (81) and the second sealing element (82) are located on the upper and lower sides of the guide hole (11), respectively. The locking cylinder (3) includes a fifth cylinder section (31) and a sixth cylinder section (32). The outer diameter of the fifth cylinder section (31) is larger than the outer diameter of the sixth cylinder section (32). The fifth cylinder section (31) is disposed between the fourth cylinder section (22) and the outer cylinder (1). A third sealing element (83) is disposed between the fifth cylinder section (31) and the fourth cylinder section (22). The sixth cylinder section (32) is located inside the second cylinder section (13). A fourth sealing element (84) is disposed between the sixth cylinder section (32) and the second cylinder section (13).

6. The differential pressure sliding sleeve according to claim 5, characterized in that, The axial gap between the third cylindrical section (21) and the fifth cylindrical section (31) is not less than the diameter of the first pin (91).

7. The differential pressure sliding sleeve according to claim 5, characterized in that, The axial distance from the first seal (81) to the upper end of the guide hole (11) is d1, the axial interval between the locking cylinder (3) and the differential pressure cylinder (2) is d2, the axial interval between two adjacent locking cylinders (3) is d3, and d1≥d2+d3.

8. The differential pressure sliding sleeve according to claim 7, characterized in that, The axial distance between the downstream locking cylinder (3) and the second cylinder section (13) is d4, d1 <d2+d3+d4。 9. A pressure testing method using a differential pressure sleeve according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Pressurize the differential pressure sleeve until the pressure exceeds the starting pressure value of the first pin (91), thereby causing the differential pressure cylinder (2) to move downward relative to the outer cylinder (1) to axially abut against the locking cylinder (3); S2. Test the differential pressure sleeve within a pressure range greater than the critical pressure value of the locking cylinder (3).

10. The pressure testing method according to claim 9, wherein the differential pressure sleeve comprises a multi-stage locking cylinder, characterized in that, It also includes the following steps: S3. The pressure is controlled between the critical pressure values ​​of the first-stage locking cylinder and the second-stage locking cylinder, and the differential pressure cylinder (2) pushes the first-stage locking cylinder (3) to move to axial contact with the second-stage locking cylinder (3); S4. Test the differential pressure sleeve within a pressure range greater than the critical pressure value of the secondary locking cylinder (3); S5. Following steps S3 and S4, gradually reduce the pressure to test the differential pressure sleeve.

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