Packer capable of being closed at constant pressure and repeatedly set

Abstract

The invention provides a constant-pressure closing and repeated setting packer which comprises a central pipe, and a constant-pressure spring is coaxially sleeved on the central pipe. The closing piston is annular, the upper end and the lower end of the closing piston are opened in the circumferential direction and the axial direction, the closing piston is coaxially arranged on the center pipe in a sleeving mode, and the closing piston can push the constant-pressure spring to move from bottom to top in the axial direction through high-pressure liquid in the cavity. The liquid conveying device further comprises a closed bridge type connector, the bridge type connector is coaxially arranged on the central pipe in a sleeving mode, and a liquid conveying opening is formed in the bridge type connector. And a liquid inlet is also formed in the central pipe. And the cavity in the closing piston can be communicated with the liquid inlet. The liquid conveying opening can be closed or opened through movement of the liquid conveying opening, and the liquid conveying opening can be communicated with the cavity in the closing piston. The device can prevent a rubber sleeve in the packer from continuously building pressure and expanding at a liquid conveying port under the set pressure, and the situation that the packer is damaged in a broken soft rock stratum and a coal seam or cracks in a non-crack-initiation area are expanded due to setting of the packer under the continuous pressure is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of enhanced coal mine gas extraction and strata pressure control, relates to hydraulic fracturing technology, and specifically relates to a packer with constant pressure closing and repeated setting Background Art

[0002] In underground coal mine mining, fracturing technology is commonly used to control strong strata pressure disasters. When using the hydraulic fracturing construction technology, the setting effect of the hole-internal sealing device is one of the important factors affecting the quality of hydraulic fracture formation. The setting effect of the sealing device is greatly affected by the operating environment. Therefore, it is particularly important to design a suitable sealing device for different operating environments or rock stratum properties. For example, Chinese Patent with application number CN113356787A discloses a retrievable downhole packer resistant to high temperature and high pressure. This device uses two sets of clamping connections to improve structural stability and has stronger high-pressure resistance. By setting high-temperature-resistant rubber cylinders, its high-temperature resistance characteristics are improved, overcoming the problems of complex packer structure, difficult setting and unsealing, long cycle, and high operating cost existing in the prior art. Another Chinese Patent with application number CN202321264304.X discloses an expandable wear-resistant packer for downhole long borehole hydraulic fracturing, which includes a rubber cylinder arranged outside the central pipe, and capsule shoulders respectively arranged at both ends of the rubber cylinder. The capsule shoulder includes a fixing part and a rubber protection part. One side of the fixing part is connected to the central pipe, a fixing hole is arranged in the fixing part, one side of the rubber protection part extends into the fixing hole and is connected to the fixing part, and the other side of the rubber protection part extends out of the fixing part, and the inner wall of the rubber protection part contacts the outer wall of the rubber cylinder. This effectively avoids the direct contact between the rubber cylinder and the sealing connection, solving the problems of easy wear, low pressure resistance, and non-reusability of the rubber cylinder.

[0003] Most coal seams in China are soft and fragmented, with low gas permeability and difficult hole formation in coal seam drilling. There are also soft and fragmented rock strata in the roof fracturing layer, resulting in difficult setting of the packer, easy over-expansion and damage of the packer, or excessive setting pressure before fracturing, leading to premature cracks in non-fracturing positions, poor setting effect, and difficulty in forming effective cracks in the set fracture initiation area. The packers in the prior art mainly focus on the upgrade of appearance and materials, and rarely start from the optimization of internal structure, making it difficult to fundamentally solve the problem of difficult setting of the packer in complex environments, with low versatility. Moreover, there is even less prior art for relevant soft and fragmented rock strata. Therefore, it is urgent to carry out research on realizing efficient setting of the packer in soft and fragmented coal and rock strata through internal structure optimization. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a packer with constant pressure closing and repeated setting, so as to solve the technical problem that the setting effect of the packer in soft and fragmented coal and rock strata in the prior art needs to be further improved.

[0005] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0006] A packer with constant-pressure closing and repeated setting, comprising a central tube, and a rubber cylinder coaxially sleeved on the central tube.

[0007] An upper joint with a hollow interior and both axial ends open is coaxially sleeved on the upper section of the central tube in the axial direction, and is connected between the inner side wall of the lower section of the upper joint in the axial direction and the outer side wall of the upper section of the central tube; a constant-pressure spring is also coaxially sleeved on the central tube, and the upper end of the constant-pressure spring in the axial direction abuts against the lower end of the upper joint in the axial direction.

[0008] It also includes a closing piston, which is a hollow structure with both axial ends open. The closing piston is coaxially sleeved on the central tube, abuts against the lower end of the constant-pressure spring in the axial direction, and can push the constant-pressure spring to move upward in the axial direction.

[0009] The closing piston includes, from top to bottom in the axial direction, an integrally formed piston upper-end sealing section, a piston middle cavity section, and a piston lower-end switching section; a sealed and movable connection is provided between the inner side wall of the piston upper-end sealing section and the outer side wall of the central tube; the inner diameter of the piston middle cavity section is larger than the outer diameter of the central tube, and the inner diameter of the piston middle cavity section is larger than the inner diameter of the piston lower-end switching section.

[0010] It also includes a bridge connector, which is a hollow structure with both axial ends open. The bridge connector is coaxially sleeved on the central tube.

[0011] The bridge connector includes, from top to bottom in the axial direction, an integrally formed connector sealing section, a piston movable lower section, a connector mounting upper section, a connector mounting middle section, and a connector mounting lower section.

[0012] The inner diameter of the connector sealing section is equal to the outer diameter of the central tube, and a sealed and interconnected connection is provided between the inner side wall of the connector sealing section and the outer side wall of the central tube. The upper end of the connector sealing section in the axial direction is located at the lower end of the piston upper-end sealing section in the axial direction; the outer diameter of the connector sealing section is equal to the inner diameter of the piston lower-end switching section, and a sealed and movable connection can be provided between the outer side wall of the connector sealing section and the inner side wall of the piston lower-end switching section.

[0013] The inner diameter of the piston movable lower section is larger than the outer diameter of the central tube, the outer diameter of the piston movable lower section is equal to the inner diameter of the piston lower-end switching section, and a sealed and movable connection can be provided between the outer side wall of the piston movable lower section and the inner side wall of the piston lower-end switching section.

[0014] The upper end of the connector mounting upper section can limit the axial movement of the piston lower-end switching section.

[0015] A plurality of liquid inlets penetrating the side wall are also provided on the central tube, and the liquid inlets are arranged between the piston upper-end sealing section and the connector sealing section.

[0016] The annular cavity formed by the outer sidewall of the central tube, the axial bottom of the upper piston sealing section, the inner sidewall of the middle piston cavity section, the axial top of the connector sealing section, the outer sidewall of the connector sealing section, the outer sidewall of the lower movable piston section, and the axial top of the lower piston switch section is the first high-pressure liquid flow cavity.

[0017] A liquid delivery port penetrating the sidewall is also provided on the upper part near the upper end of the lower movable piston section.

[0018] The annular gap between the inner sidewall of the lower movable piston section and the outer sidewall of the central tube is the first annular liquid flow channel.

[0019] The annular cavity formed by the inner sidewalls of the upper connector mounting section, the middle connector mounting section, the lower connector mounting section, and the outer sidewall of the central tube is the second high-pressure liquid flow cavity.

[0020] The inner cavity of the central tube, the liquid inlet, the first high-pressure liquid flow cavity, the liquid delivery port, the first annular liquid flow channel, the second high-pressure liquid flow cavity, and the rubber cylinder can be sequentially connected and communicated to form a liquid drive channel.

[0021] When the central tube is in a pressurized state, the closing piston moves upward axially to push the constant pressure spring to compress. When the constant pressure spring reaches the compression threshold state, the lower piston switch section can close the liquid drive channel between the first high-pressure liquid flow cavity and the liquid delivery port, realizing the constant pressure closing of the high-pressure liquid in the rubber cylinder.

[0022] When the central tube is in a pressure relief state, the compressed constant pressure spring pushes the closing piston to move downward axially. When the constant pressure spring returns to the initial state, the lower piston switch section can open the liquid drive channel between the first high-pressure liquid flow cavity and the liquid delivery port, realizing the pressure relief of the high-pressure liquid in the rubber cylinder.

[0023] The present invention also has the following technical features:

[0024] Specifically, the outer diameter of the upper connector mounting section is greater than or equal to the outer diameter of the lower piston switch section, and the inner diameter of the upper connector mounting section is greater than the outer diameter of the central tube; an outer cylinder with a hollow interior and both axial ends open is coaxially sleeved on the upper connector mounting section, and the inner sidewall of the lower half of the outer cylinder is connected to the outer sidewall of the upper connector mounting section.

[0025] The inner diameter of the middle connector mounting section is greater than the outer diameter of the central tube, and the outer diameter of the middle connector mounting section is equal to the outer diameter of the outer cylinder.

[0026] The inner diameter of the lower section of the connector installation is larger than the outer diameter of the central tube. An upper rubber barrel assembly tube that is hollow inside and open at both axial ends is coaxially sleeved on the lower section of the connector installation. The outer diameter of the upper rubber barrel assembly tube is equal to the outer diameter of the middle section of the connector installation. The inner side wall of the upper section of the thin-walled section of the upper rubber barrel assembly tube and the outer side wall of the lower section of the connector installation are sealed and connected to each other.

[0027] Specifically, the outer tube includes, from top to bottom in the axial direction, an integrally formed upper outer tube installation section, a constant pressure spring piston moving section, and a lower outer tube installation section.

[0028] The upper outer tube installation section is coaxially sleeved on the lower axial section of the upper joint, and the inner side wall of the upper outer tube installation section is connected to the outer side wall of the lower axial section of the upper joint.

[0029] The constant pressure spring piston moving section is coaxially sleeved on the constant pressure spring and the closing piston from top to bottom in sequence. The closing piston can push the constant pressure spring to move upward in the constant pressure spring piston moving section.

[0030] The lower outer tube installation section is coaxially sleeved on the upper section of the connector installation, and the inner side wall of the lower outer tube installation section is connected to the outer side wall of the upper section of the connector installation.

[0031] Specifically, a first upper rubber barrel fixing piece that is hollow inside and open at both axial ends is coaxially sleeved on the central tube. The first upper rubber barrel fixing piece is arranged at the lower axial end of the lower section of the connector installation. The inner diameter of the first upper rubber barrel fixing piece is larger than the outer diameter of the central tube. The annular gap between the inner side wall of the first upper rubber barrel fixing piece and the outer side wall of the central tube is the second annular liquid flow channel. The outer side wall of the first upper rubber barrel fixing piece is connected to the inner side wall of the lower section of the thin-walled section of the upper rubber barrel assembly tube.

[0032] A second upper rubber barrel fixing piece that is hollow inside and open at both axial ends is also coaxially sleeved on the central tube. The second upper rubber barrel fixing piece is arranged at the lower axial end of the first upper rubber barrel fixing piece. The inner diameter of the second upper rubber barrel fixing piece is larger than the outer diameter of the central tube. The annular gap between the inner side wall of the second upper rubber barrel fixing piece and the outer side wall of the central tube is the third annular liquid flow channel.

[0033] The rubber barrel is arranged at the lower axial end of the first upper rubber barrel fixing piece. The inner diameter of the rubber barrel is larger than the outer diameter of the central tube. The upper axial end of the rubber barrel is connected to the lower axial end of the first upper rubber barrel fixing piece. The inner side wall of the upper axial section of the rubber barrel is connected to the outer side wall of the second upper rubber barrel fixing piece. The annular gap between the inner side wall of the rubber barrel and the outer side wall of the central tube is the fourth annular liquid flow channel. The outer side wall of the upper axial section of the rubber barrel is connected to the inner side wall of the rear wall section of the upper rubber barrel assembly tube.

[0034] Specifically, a second fixing member at the lower end of the rubber cylinder, which is internally hollow and open at both axial ends, is also coaxially sleeved on the central tube. The inner diameter of the second fixing member at the lower end of the rubber cylinder is larger than the outer diameter of the central tube. The second fixing member at the lower end of the rubber cylinder and the second fixing member at the upper end of the rubber cylinder are symmetrically arranged in the rubber cylinder in the axial direction in a mirror image manner.

[0035] A first fixing member at the lower end of the rubber cylinder, which is internally hollow and open at both axial ends, is also coaxially sleeved on the central tube. The inner diameter of the first fixing member at the lower end of the rubber cylinder is larger than the outer diameter of the central tube. The first fixing member at the lower end of the rubber cylinder and the first fixing member at the upper end of the rubber cylinder are symmetrically arranged at both ends of the rubber cylinder in the axial direction in a mirror image manner.

[0036] A lower rubber cylinder assembly cylinder, which is internally hollow and open at both axial ends, is also coaxially sleeved on the lower axial section of the rubber cylinder. The lower rubber cylinder assembly cylinder and the upper rubber cylinder assembly cylinder are symmetrically arranged at both ends of the rubber cylinder in the axial direction in a mirror image manner.

[0037] A lower joint, which is internally hollow and open at both axial ends, is also coaxially sleeved on the central tube. A floating head is arranged between the first fixing member at the lower end of the rubber cylinder, the lower rubber cylinder assembly cylinder and the lower joint.

[0038] Specifically, the outer diameter of the lower rubber cylinder assembly cylinder is equal to the outer diameter of the upper rubber cylinder assembly cylinder. The lower rubber cylinder assembly cylinder includes, from top to bottom in the axial direction, a thick-wall section of the lower rubber cylinder assembly cylinder and a thin-wall section of the lower rubber cylinder assembly cylinder that are integrally formed.

[0039] The inner side wall of the thick-wall section of the lower rubber cylinder assembly cylinder is connected to the outer side wall of the lower axial section of the rubber cylinder.

[0040] The inner side wall of the upper half of the thin-wall section of the lower rubber cylinder assembly cylinder is connected to the outer side wall of the first fixing member at the lower end of the rubber cylinder.

[0041] The inner side wall of the lower half of the thin-wall section of the lower rubber cylinder assembly cylinder is connected to the outer side wall of the floating head.

[0042] Specifically, the outer diameters of the upper axial section and the lower axial section of the rubber cylinder are both smaller than the outer diameter of the middle axial section of the rubber cylinder.

[0043] The outer diameter of the middle axial section of the rubber cylinder is [compared with] the outer diameter of the upper rubber cylinder assembly cylinder.

[0044] The inner diameters of the upper axial section and the lower axial section of the rubber cylinder are both larger than the inner diameter of the middle axial section of the rubber cylinder.

[0045] Specifically, the second fixing member at the lower end of the rubber cylinder is coaxially sleeved on the central pipe. The inner diameter of the second fixing member at the lower end of the rubber cylinder is larger than the outer diameter of the central pipe, and the annular gap between the inner side wall of the second fixing member at the lower end of the rubber cylinder and the outer side wall of the central pipe is the fifth annular liquid flow channel; the outer side wall of the second fixing member at the lower end of the rubber cylinder is connected to the inner side wall of the lower axial section of the rubber cylinder.

[0046] Specifically, the first fixing member at the lower end of the rubber cylinder is coaxially sleeved on the central pipe. The inner diameter of the first fixing member at the lower end of the rubber cylinder is larger than the outer diameter of the central pipe, and the annular gap between the inner side wall of the first fixing member at the lower end of the rubber cylinder and the outer side wall of the central pipe is the sixth annular liquid flow channel.

[0047] Compared with the prior art, the present invention has the following technical effects:

[0048] (Ⅰ) The device in the present invention can prevent the rubber cylinder in the packer from continuously being pressured and expanding at the set pressure at the liquid delivery port, avoiding damage to the packer caused by setting the packer under continuous pressure in soft broken rock formations and coal seams or causing crack propagation in non-fracture initiation areas, and not affecting normal liquid injection and pressure increase at the set setting pressure, achieving efficient and effective fracturing.

[0049] (Ⅱ) The setting of various pressure values in the device of the present invention is achieved by different constant pressure spring specifications, that is, different stiffness coefficients. Therefore, only by changing the internal constant pressure spring can the transformation of the set pressure value be achieved, so as to adapt to soft broken coal and rock formations under various occurrence environments and quantitatively control the expansion size of the packer rubber cylinder.

[0050] (Ⅲ) After the pressure is released in the device of the present invention, the rubber cylinder returns to its original state by the rebound of the constant pressure spring, realizing efficient repeated setting in soft broken rock horizons.

[0051] (Ⅳ) The device in the present invention has the characteristics of convenient operation, high setting efficiency and strong versatility, and can effectively solve the problem of difficult setting in soft broken coal and rock formations. Description of the Drawings

[0052] Figure 1 is the overall structural schematic diagram of the device in the present invention.

[0053] Figure 2 is the sectional structural schematic diagram of the device in the present invention.

[0054] Figure 3 is Figure 2 the equal-proportion partial enlarged view of part A in

[0055] The meanings of the reference numerals in the figure are as follows: 1 - central tube, 2 - upper joint, 3 - constant pressure spring, 4 - closing piston, 5 - bridge connector, 6 - liquid inlet, 7 - first high-pressure liquid flow cavity, 8 - liquid delivery port, 9 - first annular liquid flow channel, 10 - outer cylinder, 11 - upper rubber barrel assembly cylinder, 12 - second high-pressure liquid flow cavity, 13 - first fixing part at the upper end of the rubber barrel, 14 - second annular liquid flow channel, 15 - second fixing part at the upper end of the rubber barrel, 16 - third annular liquid flow channel, 17 - rubber barrel, 18 - fourth annular liquid flow channel, 19 - second fixing part at the lower end of the rubber barrel, 20 - first fixing part at the lower end of the rubber barrel, 21 - lower rubber barrel assembly cylinder, 22 - floating head, 23 - lower joint, 24 - fifth annular liquid flow channel, 25 - sixth annular liquid flow channel, 26 - first sealing ring, 27 - second sealing ring, 28 - third sealing ring, 29 - fourth sealing ring, 30 - fifth sealing ring, 31 - sixth sealing ring, 32 - seventh sealing ring, 33 - eighth sealing ring.

[0056] 401 - upper piston sealing section, 402 - middle piston cavity section, 403 - lower piston switch section.

[0057] 501 - connector sealing section, 502 - lower movable piston section, 503 - upper connector mounting section, 504 - middle connector mounting section, 505 - lower connector mounting section.

[0058] 1001 - upper outer cylinder mounting section, 1002 - constant pressure spring piston movable section,1003 - lower outer cylinder mounting section.

[0059] 2101 - thick wall section of the lower rubber barrel assembly cylinder, 2102 - thin wall section of the lower rubber barrel assembly cylinder.

[0060] The following further elaborates on the specific content of the present invention in conjunction with the drawings and embodiments. Specific Embodiments

[0061] It should be noted that all the devices, components, and materials in the present invention, unless otherwise specified, are all the devices, components, and materials known in the prior art. For example, the bridge connector uses a known bridge connector, and the rubber barrel uses a known rubber barrel.

[0062] Complying with the above technical solutions, the following gives specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solutions of this application fall within the protection scope of the present invention.

[0063] Embodiment:

[0064] This embodiment provides a packer with constant pressure closing and repeated setting, as shown in Figure 1 and Figure 2As shown, it includes a central tube 1, and a rubber cylinder 17 is also coaxially sleeved on the central tube 1.

[0065] As Figures 1 to 3 shown, an upper joint 2 with a hollow interior and both axial ends open is coaxially sleeved on the upper axial section of the central tube 1, and it is connected between the inner side wall of the lower axial section of the upper joint 2 and the outer side wall of the upper axial section of the central tube 1; a constant pressure spring 3 is also coaxially sleeved on the central tube 1, and the upper axial end of the constant pressure spring 3 abuts against the lower axial end of the upper joint 2.

[0066] As Figure 2 and Figure 3 shown, it also includes a closing piston 4, which is a hollow structure with both axial ends open. The closing piston 4 is coaxially sleeved on the central tube 1, the closing piston 4 abuts against the lower axial end of the constant pressure spring 3, and the closing piston 4 can push the constant pressure spring 3 to move axially from bottom to top.

[0067] As Figure 2 and Figure 3 shown, the closing piston 4 includes, from top to bottom in the axial direction, an integrally formed piston upper end sealing section 401, a piston middle cavity section 402, and a piston lower end switch section 403; there is a sealed and movable connection between the inner side wall of the piston upper end sealing section 401 and the outer side wall of the central tube 1; the inner diameter of the piston middle cavity section 402 is larger than the outer diameter of the central tube 1, and the inner diameter of the piston middle cavity section 402 is larger than the inner diameter of the piston lower end switch section 403.

[0068] As Figure 2 and Figure 3 shown, it also includes a bridge connection head 5, which is a hollow structure with both axial ends open. The bridge connection head 5 is coaxially sleeved on the central tube 1.

[0069] As Figure 2 and Figure 3 shown, the bridge connection head 5 includes, from top to bottom in the axial direction, an integrally formed connection head sealing section 501, a piston movable lower section 502, a connection head mounting upper section 503, a connection head mounting middle section 504, and a connection head mounting lower section 505.

[0070] As Figure 2 and Figure 3 shown, the inner diameter of the connection head sealing section 501 is equal to the outer diameter of the central tube 1, there is a sealed and interconnected relationship between the inner side wall of the connection head sealing section 501 and the outer side wall of the central tube 1, and the upper axial end of the connection head sealing section 501 is located at the lower axial end of the piston upper end sealing section 401; the outer diameter of the connection head sealing section 501 is equal to the inner diameter of the piston lower end switch section 403, and there can be a sealed and movable connection between the outer side wall of the connection head sealing section 501 and the inner side wall of the piston lower end switch section 403.

[0071] As Figure 2 andFigure 3 As shown, the inner diameter of the lower movable section 502 of the piston is greater than the outer diameter of the central tube 1, and the outer diameter of the lower movable section 502 of the piston is equal to the inner diameter of the lower switch section 403 of the piston. A sealed and movable connection can be achieved between the outer side wall of the lower movable section 502 of the piston and the inner side wall of the lower switch section 403 of the piston.

[0072] As Figure 2 and Figure 3 shown, the upper end of the upper connecting head mounting section 503 can limit the axial movement of the lower switch section 403 of the piston.

[0073] As Figure 2 and Figure 3 shown, a plurality of liquid inlet ports 6 penetrating the side wall are also provided on the central tube 1, and the liquid inlet ports 6 are arranged between the upper piston sealing section 401 and the connecting head sealing section 501.

[0074] As Figure 2 and Figure 3 shown, the annular cavity formed by the outer side wall of the central tube 1, the axial bottom of the upper piston sealing section 401, the inner side wall of the middle piston cavity section 402, the axial top of the connecting head sealing section 501, the outer side wall of the connecting head sealing section 501, the outer side wall of the lower movable section 502 of the piston, and the axial top of the lower switch section 403 of the piston is the first high-pressure liquid flow cavity 7.

[0075] As Figure 2 and Figure 3 shown, a liquid delivery port 8 penetrating the side wall is also provided on the lower movable section 502 of the piston near the upper end.

[0076] As Figure 2 and Figure 3 shown, the annular gap between the inner side wall of the lower movable section 502 of the piston and the outer side wall of the central tube 1 is the first annular liquid flow channel 9.

[0077] As Figure 2 shown, the annular cavity formed by the inner side wall of the upper connecting head mounting section 503, the inner side wall of the middle connecting head mounting section 504, the inner side wall of the lower connecting head mounting section 505, and the outer side wall of the central tube 1 is the second high-pressure liquid flow cavity 12.

[0078] As Figure 2 shown, the inner cavity of the central tube 1, the liquid inlet port 6, the first high-pressure liquid flow cavity 7, the liquid delivery port 8, the first annular liquid flow channel 9, the second high-pressure liquid flow cavity 12, and the rubber cylinder 17 can be connected in sequence to form a liquid drive channel.

[0079] When the central tube 1 is under pressure, the closing piston 4 moves upward along the axis to push and compress the constant-pressure spring 3. When the constant-pressure spring 3 reaches the compressed threshold state, the switch section 403 at the lower end of the piston can close the liquid driving channel between the first high-pressure liquid flow cavity 7 and the liquid delivery port 8, realizing the constant-pressure closing of the high-pressure liquid in the rubber cylinder 17.

[0080] When the central tube 1 is in a pressure relief state, the compressed constant-pressure spring 3 pushes the closing piston 4 to move downward along the axis. When the constant-pressure spring 3 returns to its initial state, the switch section 403 at the lower end of the piston can open the liquid driving channel between the first high-pressure liquid flow cavity 7 and the liquid delivery port 8, realizing the pressure relief of the high-pressure liquid in the rubber cylinder 17.

[0081] In this embodiment, the central tube 1 is a tubular structure with a hollow interior and open ends at both axial ends. The outer diameter at each position of the central tube 1 is equal, and the inner diameter at each position of the central tube 1 is equal.

[0082] In this embodiment, the inner side wall of the lower axial section of the upper joint 2 and the outer side wall of the upper axial section of the central tube 1 are connected by threaded steel, and the threaded steel is well-known threaded steel.

[0083] In this embodiment, the material of the constant-pressure spring 3 is silicon manganese constant-pressure spring steel, and the silicon manganese constant-pressure spring steel is well-known silicon manganese constant-pressure spring steel.

[0084] In this embodiment, the outer diameter of the constant-pressure spring 3 is smaller than the outer diameter of the upper piston sealing section 401.

[0085] In this embodiment, between the inner side wall of the upper piston sealing section 401 and the outer side wall of the central tube 1, a plurality of first sealing rings 26 are used for sealing, and the first sealing rings 26 are well-known and commonly used O-ring seals.

[0086] In this embodiment, between the outer side wall of the lower movable piston section 502 and the inner side wall of the lower piston switch section 403, a plurality of second sealing rings 27 are used for sealing, and the second sealing rings 27 are well-known and commonly used O-ring seals.

[0087] In this embodiment, between the inner side wall of the connector sealing section 501 and the outer side wall of the central tube 1, a plurality of third sealing rings 28 are used for sealing, and the third sealing rings 28 are well-known and commonly used O-ring seals.

[0088] In this embodiment, steel belts are arranged inside the side wall of the rubber cylinder 17.

[0089] As a preferred solution of this embodiment, as Figure 2As shown, the outer diameter of the upper connecting head mounting section 503 is greater than or equal to the outer diameter of the lower piston switch section 403, and the inner diameter of the upper connecting head mounting section 503 is greater than the outer diameter of the central tube 1; an outer cylinder 10 with a hollow interior and open at both axial ends is coaxially sleeved on the upper connecting head mounting section 503, and the inner side wall of the lower half section of the outer cylinder 10 is connected to the outer side wall of the upper connecting head mounting section 503.

[0090] As Figure 2 shown, the inner diameter of the middle connecting head mounting section 504 is greater than the outer diameter of the central tube 1, and the outer diameter of the middle connecting head mounting section 504 is equal to the outer diameter of the outer cylinder 10.

[0091] As Figure 2 shown, the inner diameter of the lower connecting head mounting section 505 is greater than the outer diameter of the central tube 1, and an upper rubber cylinder assembly cylinder 11 with a hollow interior and open at both axial ends is coaxially sleeved on the lower connecting head mounting section 505; the outer diameter of the upper rubber cylinder assembly cylinder 11 is equal to the outer diameter of the middle connecting head mounting section 504; the inner side wall of the upper section of the thin wall section of the upper rubber cylinder assembly cylinder 11 is sealed and connected to the outer side wall of the lower connecting head mounting section 505.

[0092] In this embodiment, a plurality of fourth sealing rings 29 are used to seal between the inner side wall of the upper section of the thin wall section of the upper rubber cylinder assembly cylinder 11 and the outer side wall of the lower connecting head mounting section 505, and the fourth sealing rings 29 are O - shaped sealing rings commonly used and known.

[0093] In this embodiment, the bridge - type connecting head 5 is used to close the connection between the piston 4 and the upper rubber cylinder assembly cylinder 11.

[0094] In this embodiment, the inner side wall of the lower half section of the outer cylinder 10 and the outer side wall of the upper connecting head mounting section 503 are connected by threads.

[0095] In this embodiment, the inner side wall of the upper section of the thin wall section of the upper rubber cylinder assembly cylinder 11 and the outer side wall of the lower connecting head mounting section 505 are connected by threads.

[0096] As a preferred solution of this embodiment, as Figure 2 shown, the outer cylinder 10 axially includes, from top to bottom, an integrally formed outer cylinder upper mounting section 1001, a constant - pressure spring piston moving section 1002, and an outer cylinder lower mounting section 1003.

[0097] As Figure 2 shown, the outer cylinder upper mounting section 1001 is coaxially sleeved on the lower axial section of the upper joint 2, and the inner side wall of the outer cylinder upper mounting section 1001 is connected to the outer side wall of the lower axial section of the upper joint 2.

[0098] As Figure 2As shown, the movable section 1002 of the constant-pressure spring piston is coaxially sleeved on the constant-pressure spring 3 and the closing piston 4 from top to bottom in sequence. The closing piston 4 can push the constant-pressure spring 3 to move upward in the movable section 1002 of the constant-pressure spring piston.

[0099] As Figure 2 shown, the lower end mounting section 1003 of the outer cylinder is coaxially sleeved on the upper mounting section 503 of the connector. The inner side wall of the lower end mounting section 1003 of the outer cylinder is connected to the outer side wall of the upper mounting section 503 of the connector.

[0100] In this embodiment, the inner side wall of the upper end mounting section 1001 of the outer cylinder and the outer side wall of the lower axial section of the upper joint 2 are connected by threaded steel, and the threaded steel is known threaded steel.

[0101] In this embodiment, the inner side wall of the upper end mounting section 1001 of the outer cylinder and the outer side wall of the lower axial section of the upper joint 2 are also fixed by a clamping groove, and the clamping groove is a commonly used clamping groove known in the art.

[0102] In this embodiment, the wall thickness of the side wall of the lower end mounting section 1003 of the outer cylinder is less than the wall thickness of the side wall of the upper end mounting section 1001 of the outer cylinder; the inner side wall of the lower end mounting section 1003 of the outer cylinder and the outer side wall of the upper mounting section 503 of the connector are fixed by a clamping groove, and the clamping groove is a commonly used clamping groove known in the art.

[0103] As a preferred solution of this embodiment, as Figure 2 shown, a first upper fixing member 13 of the rubber cylinder with a hollow interior and both axial ends open is also coaxially sleeved on the central tube 1. The first upper fixing member 13 of the rubber cylinder is arranged at the lower axial end of the lower mounting section 505 of the connector. The inner diameter of the first upper fixing member 13 of the rubber cylinder is greater than the outer diameter of the central tube 1. The annular gap between the inner side wall of the first upper fixing member 13 of the rubber cylinder and the outer side wall of the central tube 1 is the second annular liquid flow channel 14; the outer side wall of the first upper fixing member 13 of the rubber cylinder is connected to the inner side wall of the lower thin-walled section of the upper rubber cylinder assembly tube 11.

[0104] As Figure 2 shown, a second upper fixing member 15 of the rubber cylinder with a hollow interior and both axial ends open is also coaxially sleeved on the central tube 1. The second upper fixing member 15 of the rubber cylinder is arranged at the lower axial end of the first upper fixing member 13 of the rubber cylinder. The inner diameter of the second upper fixing member 15 of the rubber cylinder is greater than the outer diameter of the central tube 1. The annular gap between the inner side wall of the second upper fixing member 15 of the rubber cylinder and the outer side wall of the central tube 1 is the third annular liquid flow channel 16.

[0105] As Figure 2As shown, the rubber cylinder 17 is arranged at the axially lower end of the first fixing member 13 at the upper end of the rubber cylinder. The inner diameter of the rubber cylinder 17 is greater than the outer diameter of the central tube 1. The axially upper end of the rubber cylinder 17 is connected to the axially lower end of the first fixing member 13 at the upper end of the rubber cylinder. The inner side wall of the axially upper section of the rubber cylinder 17 is connected to the outer side wall of the second fixing member 15 at the upper end of the rubber cylinder. The annular gap between the inner side wall of the rubber cylinder 17 and the outer side wall of the central tube 1 is the fourth annular liquid flow channel 18. The outer side wall of the axially upper section of the rubber cylinder 17 is connected to the inner side wall of the rear wall section of the upper rubber cylinder assembly cylinder 11.

[0106] As a preferred solution of this embodiment, as Figure 2 shown, a second lower fixing member 19 of the rubber cylinder, which is internally hollow and open at both axial ends, is also coaxially sleeved on the central tube 1. The inner diameter of the second lower fixing member 19 of the rubber cylinder is greater than the outer diameter of the central tube 1. The second lower fixing member 19 of the rubber cylinder and the second upper fixing member 15 of the rubber cylinder are symmetrically arranged in the rubber cylinder 17 in the axial direction.

[0107] As Figure 2 shown, a first lower fixing member 20 of the rubber cylinder, which is internally hollow and open at both axial ends, is also coaxially sleeved on the central tube 1. The inner diameter of the first lower fixing member 20 of the rubber cylinder is greater than the outer diameter of the central tube 1. The first lower fixing member 20 of the rubber cylinder and the first upper fixing member 13 of the rubber cylinder are symmetrically arranged at both ends of the rubber cylinder 17 in the axial direction.

[0108] As Figure 2 shown, a lower rubber cylinder assembly cylinder 21, which is internally hollow and open at both axial ends, is also coaxially sleeved on the axially lower section of the rubber cylinder 17. The lower rubber cylinder assembly cylinder 21 and the upper rubber cylinder assembly cylinder 11 are symmetrically arranged at both ends of the rubber cylinder 17 in the axial direction.

[0109] As Figure 2 shown, a lower joint 23, which is internally hollow and open at both axial ends, is also coaxially sleeved on the central tube 1. A floating head 22 is arranged between the first lower fixing member 20 of the rubber cylinder, the lower rubber cylinder assembly cylinder 21 and the lower joint 23.

[0110] In this embodiment, multiple fifth sealing rings 30 are used for sealing between the inner side wall of the axially upper section of the floating head 22 and the outer side wall of the central tube 1. The fifth sealing rings 30 are known and commonly used O-shaped sealing rings.

[0111] In this embodiment, multiple sixth sealing rings 31 are used for sealing between the outer side wall of the axially upper section of the floating head 22 and the inner side wall of the lower thin-wall section of the lower rubber cylinder assembly cylinder 21. The sixth sealing rings 31 are known and commonly used O-shaped sealing rings.

[0112] In this embodiment, when the high-pressure liquid filled inside the rubber cylinder 17 expands, the floating head 22 moves along with the expansion amplitude of the rubber cylinder 17. The fifth sealing ring 30 and the sixth sealing ring 31 play a role in sealing and maintaining pressure.

[0113] In this embodiment, between the inner side wall of the upper axial section of the lower joint 23 and the outer side wall of the lower axial section of the central tube 1, a plurality of seventh sealing rings 32 are used for sealing. The seventh sealing ring 32 adopts a commonly known O-shaped sealing ring.

[0114] In this embodiment, an eighth sealing ring 33 is further provided on the lower joint 23 near the lower axial end. The eighth sealing ring 33 is used for sealing with the lower device of the packer, and the lower device of the packer is a commonly known lower device of the packer.

[0115] As a preferred solution of this embodiment, as Figure 2 shown, the outer diameter of the lower rubber cylinder assembly cylinder 21 is equal to the outer diameter of the upper rubber cylinder assembly cylinder 11. The lower rubber cylinder assembly cylinder 21 axially includes, from top to bottom, a thick-wall section 2101 of the lower rubber cylinder assembly cylinder and a thin-wall section 2102 of the lower rubber cylinder assembly cylinder which are integrally formed.

[0116] As Figure 2 shown, the inner side wall of the thick-wall section 2101 of the lower rubber cylinder assembly cylinder is connected to the outer side wall of the lower axial section of the rubber cylinder 17.

[0117] As Figure 2 shown, the inner side wall of the upper half of the thin-wall section 2102 of the lower rubber cylinder assembly cylinder is connected to the outer side wall of the first rubber cylinder lower fixing member 20.

[0118] As Figure 2 shown, the inner side wall of the lower half of the thin-wall section 2102 of the lower rubber cylinder assembly cylinder is connected to the outer side wall of the floating head 22.

[0119] As a preferred solution of this embodiment, as Figure 2 shown, the outer diameter of the upper axial section of the rubber cylinder 17 and the outer diameter of the lower axial section of the rubber cylinder 17 are both smaller than the outer diameter of the axial middle section of the rubber cylinder 17.

[0120] As Figure 2 shown, the outer diameter of the axial middle section of the rubber cylinder 17 is... the outer diameter of the upper rubber cylinder assembly cylinder 11.

[0121] As Figure 2 shown, the inner diameter of the upper axial section of the rubber cylinder 17 and the inner diameter of the lower axial section of the rubber cylinder 17 are both larger than the inner diameter of the axial middle section of the rubber cylinder 17.

[0122] As a preferred solution of this embodiment, as Figure 2As shown, the second fixing member 19 at the lower end of the rubber cylinder is coaxially sleeved on the central tube 1. The inner diameter of the second fixing member 19 at the lower end of the rubber cylinder is larger than the outer diameter of the central tube 1. The annular gap between the inner side wall of the second fixing member 19 at the lower end of the rubber cylinder and the outer side wall of the central tube 1 is the fifth annular liquid flow channel 24; the outer side wall of the second fixing member 19 at the lower end of the rubber cylinder is connected to the inner side wall of the lower axial section of the rubber cylinder 17.

[0123] As a preferred solution of this embodiment, as Figure 2 shown, the first fixing member 20 at the lower end of the rubber cylinder is coaxially sleeved on the central tube 1. The inner diameter of the first fixing member 20 at the lower end of the rubber cylinder is larger than the outer diameter of the central tube 1. The annular gap between the inner side wall of the first fixing member 20 at the lower end of the rubber cylinder and the outer side wall of the central tube 1 is the sixth annular liquid flow channel 25.

[0124] In this embodiment, the inner cavity of the central tube 1 is communicated with the liquid inlet 6. The liquid inlet 6 can be communicated with the first high-pressure liquid flow cavity 7. The first high-pressure liquid flow cavity 7 can be communicated with the liquid delivery port 8. The liquid delivery port 8 is communicated with the first annular liquid flow channel 9. The first annular liquid flow channel 9 is communicated with the second high-pressure liquid flow cavity 12. The second high-pressure liquid flow cavity 12 is communicated with the second annular liquid flow channel 14. The second annular liquid flow channel 14 is communicated with the third annular liquid flow channel 16. The third annular liquid flow channel 16 is communicated with the fourth annular liquid flow channel 18. The fourth annular liquid flow channel 18 is communicated with the fifth annular liquid flow channel 24. The fifth annular liquid flow channel 24 is communicated with the sixth annular liquid flow channel 25.

[0125] In this embodiment, the elastic force and the cavity pressure are the instantaneous forces at the corresponding time nodes and change continuously with pressurization or depressurization.

[0126] In this embodiment, the setting and control of the setting pressure of the packer are realized by the constant pressure spring 3. According to different models, that is, by selecting constant pressure springs 3 with different stiffness coefficients k, different pressure thresholds when blocking the liquid delivery port 8 are controlled under the same compression amount to adapt to the soft rock geological conditions of various occurrence environments, which specifically include the following steps:

[0127] In the initial state, both the liquid inlet 6 and the liquid delivery port 8 are located within the piston intermediate cavity section 402 of the closing piston 4. At this time, normal liquid supply and pressure boosting can be achieved. The high-pressure liquid flows from the central tube 1 successively along the liquid inlet 6, the first high-pressure liquid flow cavity 7, the liquid delivery port 8, the first annular liquid flow channel 9, the second high-pressure liquid flow cavity 12, the second annular liquid flow channel 14, the third annular liquid flow channel 16 into the fourth annular liquid flow channel 18. The rubber cylinder 17 is gradually pressurized and expanded to achieve normal setting. When the packer is normally set, with the injection of high-pressure liquid, the pressure value in the piston intermediate cavity section 402 of the closing piston 4, that is, the pressure value in the first high-pressure liquid flow cavity 7, gradually increases. Until the pressure value in the piston intermediate cavity section 402 of the closing piston 4 is greater than the elastic force of the constant-pressure spring 3, the closing piston 4 pushes the constant-pressure spring 3 to be slowly compressed, that is, the closing piston 4 and the constant-pressure spring 3 as a whole move in the direction of the upper joint 2.

[0128] At this time, the first sealing ring 26 seals the connection position between the central tube 1 and the piston upper sealing section in the closing piston 4, and the fourth sealing ring 29 seals the connection position between the lower connection section 505 of the bridge connection head 5 and the upper rubber cylinder assembly tube 11, preventing the high-pressure liquid in the first high-pressure liquid flow cavity 7 and the fourth annular liquid flow channel 18 in the rubber cylinder 17 from overflowing, resulting in pressure loss and poor setting effect. During the setting process, the floating head 22 moves and buffers with the expansion amplitude of the rubber cylinder 17 to prevent the internal steel belt from being broken during the expansion of the rubber cylinder. The fifth sealing ring 30 plays a role in sealing and controlling pressure.

[0129] When the set pressure determined by the physical and mechanical parameters of the construction coal seam stratum is reached, the closing piston 4 pushes the constant-pressure spring 3 to reach the compression threshold value. At this time, the compression amount of the constant-pressure spring 3, that is, the displacement amount of the closing piston 4 moving axially upward, satisfies the complete sealing of the contact between the lower piston switch section 403 and the lower movable piston section 502 and cuts off the connection between the first high-pressure liquid flow cavity 7 and the liquid delivery port 8, that is, blocking the liquid inlet. At this time, the supply of high-pressure liquid in the rubber cylinder 17 is cut off, the pressure in the rubber cylinder 17 no longer increases, and the expansion size remains unchanged, achieving constant-pressure closing, avoiding the continuous pressurization of the rubber cylinder 17 causing excessive expansion and damage of the rubber cylinder 17 in soft and broken rock strata and coal seams, or the setting pressure being greater than the surrounding rock fracture pressure causing crack propagation at non-fracture positions.

[0130] If the surrounding rock is hard, a constant-pressure spring 3 with a larger stiffness coefficient k is selected, and a larger setting pressure is set under the same compression amount of the constant-pressure spring 3; if the surrounding rock is soft, a constant-pressure spring 3 with a smaller stiffness coefficient k is selected, and a smaller setting pressure is set under the same compression amount of the constant-pressure spring 3.

[0131] When pressure relief occurs, the supply of high-pressure liquid in the central pipe 1 stops, and the liquid in the closing piston 4 flows out from the liquid inlet 6, resulting in a gradual reduction in the pressure in the cavity of the piston intermediate cavity section 402 of the closing piston 4, that is, the pressure in the first high-pressure liquid flow cavity 7. At this time, the elastic force of the constant-pressure spring 3 is greater than the pressure in the cavity of the piston intermediate cavity section 402, so the constant-pressure spring 3 slowly rebounds and pushes the closing piston 4 back to its original position.

[0132] After the closing piston 4 is pushed back to its original position, the liquid delivery port 8 also returns to the inside of the piston intermediate cavity section 402 of the closing piston 4, that is, the liquid delivery port 8 is connected to the first high-pressure liquid flow cavity 7 again. The high-pressure liquid in the rubber barrel 17 flows out from the liquid delivery port 8 through the liquid inlet 6, and the rubber barrel 17 gradually shrinks, and the floating head 22 returns to its original position. At this time, the packer returns to the initial state of being unset, and normal liquid supply and pressure increase can be carried out. In this way, the packer can be efficiently and repeatedly set in the soft and broken coal rock stratum.

Claims

1. A packer with constant pressure closing and repeated setting, comprising a central tube (1), and a rubber cylinder (17) is coaxially sleeved on the central tube (1). It is characterized in that: An upper joint (2) with a hollow interior and open at both axial ends is coaxially sleeved on the upper axial section of the central tube (1). The inner side wall of the lower axial section of the upper joint (2) is connected to the outer side wall of the upper axial section of the central tube (1). A constant pressure spring (3) is also coaxially sleeved on the central tube (1), and the upper axial end of the constant pressure spring (3) abuts against the lower axial end of the upper joint (2); It further includes a closing piston (4). The closing piston (4) has a hollow structure with open ends at both axial ends. The closing piston (4) is coaxially sleeved on the central tube (1). The closing piston (4) abuts against the lower axial end of the constant pressure spring (3), and the closing piston (4) can push the constant pressure spring (3) to move upward axially; The closing piston (4) includes, from top to bottom in the axial direction, an integrally formed piston upper end sealing section (401), a piston middle cavity section (402), and a piston lower end switching section (403). The inner side wall of the piston upper end sealing section (401) is in sealed and movable connection with the outer side wall of the central tube (1). The inner diameter of the piston middle cavity section (402) is larger than the outer diameter of the central tube (1), and the inner diameter of the piston middle cavity section (402) is larger than the inner diameter of the piston lower end switching section (403); It further includes a bridge connection head (5). The bridge connection head (5) has a hollow structure with open ends at both axial ends. The bridge connection head (5) is coaxially sleeved on the central tube (1); The bridge connection head (5) includes, from top to bottom in the axial direction, an integrally formed connection head sealing section (501), a piston movable lower section (502), a connection head mounting upper section (503), a connection head mounting middle section (504), and a connection head mounting lower section (505); The inner diameter of the connection head sealing section (501) is equal to the outer diameter of the central tube (1). The inner side wall of the connection head sealing section (501) is in sealed and connected to the outer side wall of the central tube (1). The upper axial end of the connection head sealing section (501) is located at the lower axial end of the piston upper end sealing section (401). The outer diameter of the connection head sealing section (501) is equal to the inner diameter of the piston lower end switching section (403), and the outer side wall of the connection head sealing section (501) and the inner side wall of the piston lower end switching section (403) can be in sealed and movable connection; The inner diameter of the piston movable lower section (502) is larger than the outer diameter of the central tube (1). The outer diameter of the piston movable lower section (502) is equal to the inner diameter of the piston lower end switching section (403), and the outer side wall of the piston movable lower section (502) and the inner side wall of the piston lower end switching section (403) can be in sealed and movable connection; The upper end of the connection head mounting upper section (503) can limit the axial movement of the piston lower end switching section (403); A plurality of liquid inlet ports (6) penetrating the side wall are also provided on the central tube (1). The liquid inlet ports (6) are arranged between the piston upper end sealing section (401) and the connection head sealing section (501); The annular cavity formed by the outer sidewall of the central tube (1), the axial bottom of the upper piston sealing section (401), the inner sidewall of the middle piston cavity section (402), the axial top of the connector sealing section (501), the outer sidewall of the connector sealing section (501), the outer sidewall of the lower movable piston section (502), and the axial top of the lower piston switch section (403) is the first high-pressure liquid flow cavity (7); A liquid delivery port (8) penetrating the sidewall is further provided on the lower movable piston section (502) near the upper end; The annular gap between the inner sidewall of the lower movable piston section (502) and the outer sidewall of the central tube (1) is the first annular liquid flow channel (9); The annular cavity formed by the inner sidewalls of the upper connector mounting section (503), the middle connector mounting section (504), the lower connector mounting section (505), and the outer sidewall of the central tube (1) is the second high-pressure liquid flow cavity (12); The inner cavity of the central tube (1), the liquid inlet (6), the first high-pressure liquid flow cavity (7), the liquid delivery port (8), the first annular liquid flow channel (9), the second high-pressure liquid flow cavity (12), and the rubber cylinder (17) can be sequentially connected to form a liquid drive channel; When the central tube (1) is in a pressurized state, the closing piston (4) moves axially upward to push the constant pressure spring (3) to compress. When the constant pressure spring (3) reaches the compression threshold state, the lower piston switch section (403) can close the liquid drive channel between the first high-pressure liquid flow cavity (7) and the liquid delivery port (8), realizing the constant pressure closing of the high-pressure liquid in the rubber cylinder (17); When the central tube (1) is in a pressure relief state, the compressed constant pressure spring (3) pushes the closing piston (4) to move axially downward. When the constant pressure spring (3) returns to the initial state, the lower piston switch section (403) can open the liquid drive channel between the first high-pressure liquid flow cavity (7) and the liquid delivery port (8), realizing the pressure relief of the high-pressure liquid in the rubber cylinder (17).

2. The packer with constant pressure closing and repeated setting according to claim 1, wherein The outer diameter of the upper connector mounting section (503) is greater than or equal to the outer diameter of the lower piston switch section (403), and the inner diameter of the upper connector mounting section (503) is greater than the outer diameter of the central tube (1); An outer cylinder (10) with a hollow interior and both axial ends open is coaxially sleeved on the upper connector mounting section (503), and the inner sidewall of the lower half of the outer cylinder (10) is connected to the outer sidewall of the upper connector mounting section (503); The inner diameter of the middle connector mounting section (504) is greater than the outer diameter of the central tube (1), and the outer diameter of the middle connector mounting section (504) is equal to the outer diameter of the outer cylinder (10); The inner diameter of the lower section (505) for connector installation is larger than the outer diameter of the central tube (1). An upper rubber barrel assembly tube (11) which is internally hollow and open at both axial ends is coaxially sleeved on the lower section (505) for connector installation. The outer diameter of the upper rubber barrel assembly tube (11) is equal to the outer diameter of the middle section (504) for connector installation; the inner side wall of the upper section of the thin-wall section of the upper rubber barrel assembly tube (11) is sealed and connected to the outer side wall of the lower section (505) for connector installation.

3. The packer with constant pressure closing and repeated setting as claimed in claim 2, wherein The outer tube (10) includes, from top to bottom in the axial direction, an integrally formed upper installation section (1001) of the outer tube, a constant-pressure spring piston movable section (1002), and a lower installation section (1003) of the outer tube. The upper installation section (1001) of the outer tube is coaxially sleeved on the lower axial section of the upper joint (2), and the inner side wall of the upper installation section (1001) of the outer tube is connected to the outer side wall of the lower axial section of the upper joint (2). The constant-pressure spring piston movable section (1002) is coaxially sleeved on the constant-pressure spring (3) and the closing piston (4) in sequence from top to bottom, and the closing piston (4) can push the constant-pressure spring (3) to move upward in the constant-pressure spring piston movable section (1002). The lower installation section (1003) of the outer tube is coaxially sleeved on the upper section (503) for connector installation, and the inner side wall of the lower installation section (1003) of the outer tube is connected to the outer side wall of the upper section (503) for connector installation.

4. The packer with constant pressure closing and repeated setting as claimed in claim 2, characterized in that, A first fixing part (13) of the upper end of the rubber barrel which is internally hollow and open at both axial ends is coaxially sleeved on the central tube (1). The first fixing part (13) of the upper end of the rubber barrel is arranged at the lower axial end of the lower section (505) for connector installation. The inner diameter of the first fixing part (13) of the upper end of the rubber barrel is larger than the outer diameter of the central tube (1). The annular gap between the inner side wall of the first fixing part (13) of the upper end of the rubber barrel and the outer side wall of the central tube (1) is the second annular liquid flow channel (14); the outer side wall of the first fixing part (13) of the upper end of the rubber barrel is connected to the inner side wall of the lower section of the thin-wall section of the upper rubber barrel assembly tube (11). A second fixing part (15) of the upper end of the rubber barrel which is internally hollow and open at both axial ends is coaxially sleeved on the central tube (1). The second fixing part (15) of the upper end of the rubber barrel is arranged at the lower axial end of the first fixing part (13) of the upper end of the rubber barrel. The inner diameter of the second fixing part (15) of the upper end of the rubber barrel is larger than the outer diameter of the central tube (1). The annular gap between the inner side wall of the second fixing part (15) of the upper end of the rubber barrel and the outer side wall of the central tube (1) is the third annular liquid flow channel (16). The described rubber cylinder (17) is arranged at the lower axial end of the first fixing member (13) at the upper end of the rubber cylinder. The inner diameter of the rubber cylinder (17) is larger than the outer diameter of the central tube (1). The upper axial end of the rubber cylinder (17) is connected to the lower axial end of the first fixing member (13) at the upper end of the rubber cylinder. The inner side wall of the upper axial section of the rubber cylinder (17) is connected to the outer side wall of the second fixing member (15) at the upper end of the rubber cylinder. The annular gap between the inner side wall of the rubber cylinder (17) and the outer side wall of the central tube (1) is the fourth annular liquid flow channel (18). The outer side wall of the upper axial section of the rubber cylinder (17) is connected to the inner side wall of the rear wall section of the upper rubber cylinder assembly cylinder (11).

5. The packer with constant pressure closing and repeated setting as claimed in claim 4, characterized in that, A second lower fixing member (19) which is internally hollow and open at both axial ends is also coaxially sleeved on the central tube (1). The inner diameter of the second lower fixing member (19) is larger than the outer diameter of the central tube (1). The second lower fixing member (19) and the second upper fixing member (15) are symmetrically arranged in the rubber cylinder (17) in the axial direction in a mirror image manner. A first lower fixing member (20) which is internally hollow and open at both axial ends is also coaxially sleeved on the central tube (1). The inner diameter of the first lower fixing member (20) is larger than the outer diameter of the central tube (1). The first lower fixing member (20) and the first upper fixing member (13) are symmetrically arranged at both ends of the rubber cylinder (17) in the axial direction in a mirror image manner. A lower rubber cylinder assembly cylinder (21) which is internally hollow and open at both axial ends is also coaxially sleeved on the lower axial section of the rubber cylinder (17). The lower rubber cylinder assembly cylinder (21) and the upper rubber cylinder assembly cylinder (11) are symmetrically arranged at both ends of the rubber cylinder (17) in the axial direction in a mirror image manner. A lower joint (23) which is internally hollow and open at both axial ends is also coaxially sleeved on the central tube (1). A floating head (22) is arranged between the first lower fixing member (20) of the rubber cylinder, the lower rubber cylinder assembly cylinder (21) and the lower joint (23).

6. The packer with constant pressure closing and repeated setting as described in claim 5, characterized in that, The outer diameter of the lower rubber cylinder assembly cylinder (21) is equal to the outer diameter of the upper rubber cylinder assembly cylinder (11). The lower rubber cylinder assembly cylinder (21) includes, from top to bottom in the axial direction, a thick wall section (2101) of the lower rubber cylinder assembly cylinder and a thin wall section (2102) of the lower rubber cylinder assembly cylinder which are integrally formed. The inner side wall of the thick wall section (2101) of the lower rubber cylinder assembly cylinder is connected to the outer side wall of the lower axial section of the rubber cylinder (17). The inner side wall of the upper half of the thin wall section (2102) of the lower rubber cylinder assembly cylinder is connected to the outer side wall of the first lower fixing member (20) of the rubber cylinder. The inner side wall of the lower half of the thin wall section (2102) of the lower rubber cylinder assembly cylinder is connected to the outer side wall of the floating head (22).

7. The packer for constant-pressure closing and repeated setting according to claim 5, characterized in that The outer diameter of the upper axial section of the rubber cylinder (17) and the outer diameter of the lower axial section of the rubber cylinder (17) are both smaller than the outer diameter of the axial middle section of the rubber cylinder (17). The outer diameter of the axial middle section of the rubber cylinder (17) is larger than the outer diameter of the upper rubber cylinder assembly cylinder (11). The inner diameter of the upper axial section of the rubber cylinder (17) and the inner diameter of the lower axial section of the rubber cylinder (17) are both larger than the inner diameter of the axial middle section of the rubber cylinder (17).

8. The packer with constant pressure closing and repeated setting as claimed in claim 5, characterized in that, The second fixing member (19) at the lower end of the rubber cylinder is coaxially sleeved on the central tube (1). The inner diameter of the second fixing member (19) at the lower end of the rubber cylinder is larger than the outer diameter of the central tube (1). The annular gap between the inner side wall of the second fixing member (19) at the lower end of the rubber cylinder and the outer side wall of the central tube (1) is the fifth annular liquid flow channel (24); the outer side wall of the second fixing member (19) at the lower end of the rubber cylinder is connected to the inner side wall of the lower axial section of the rubber cylinder (17).

9. The packer with constant pressure closing and repeated setting as claimed in claim 5, wherein, The first fixing member (20) at the lower end of the rubber cylinder is coaxially sleeved on the central tube (1). The inner diameter of the first fixing member (20) at the lower end of the rubber cylinder is larger than the outer diameter of the central tube (1). The annular gap between the inner side wall of the first fixing member (20) at the lower end of the rubber cylinder and the outer side wall of the central tube (1) is the sixth annular liquid flow channel (25).

Images