A hydraulic anchor and its usage method

Abstract

The present invention discloses a hydraulic anchor and its usage method, relating to the technical field of hydraulic anchors. Multiple slips are provided on the slips, and shear pin holes are provided at the bottom of the side walls of the slip teeth; multiple slip holes corresponding to the slip teeth are provided on the slip seat, and locking holes are provided on the inner walls of the slip holes; a locking shear pin and a pin spring are installed in the locking holes, and the locking shear pin is adapted to the shear pin holes; multiple spring hole seats are provided at the bottom of the slip seat, the upper ends of the tooth block support springs are located in the spring hole seats, and the lower ends abut against the slips; when the slips are located at the bottom of the slip groove, the locking shear pin abuts against the side surface of the slip teeth; the anchoring method of this hydraulic anchor is to anchor by applying pressure in the annulus between the tubing and the casing, and the anchoring is also released by applying pressure in the annulus between the tubing and the casing. This working method is different from traditional hydraulic anchors; this device can lock the slips at the maximum anchoring height of the slips, effectively improving the reliability of the setting of this hydraulic anchor.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic anchors, and particularly relates to a hydraulic anchor and a using method thereof. Background Art

[0002] A hydraulic anchor is a commonly used downhole anchoring tool in the operations of fracturing, acidizing, water injection, etc. in oil, gas, and water wells. By building pressure in the tubing, the anchor claw itself is a piston structure and extends outward under the action of liquid pressure to fit against the inner wall of the casing to achieve the anchoring action; when the oil-casing pressure is balanced, the anchor claw retracts under the elastic force of the spring in the baffle to release the anchoring action.

[0003] Currently, conventional hydraulic anchors all use a return spring to limit and correct the position of the anchor claw by means of a reset pressing plate; after the anchoring action is completed, when the hydraulic pressure of the central string is relieved, the anchor claw automatically retracts and cannot continue to complete the anchoring work; some hydraulic anchors need to cooperate with other packers (such as need to cooperate with combined strings such as Y211 seal and Y221 seal) to continue to complete the work.

[0004] These traditional hydraulic anchors all have the following drawbacks: 1. When there is no pressure in the well and there is no other packer to cooperate for fixed limiting, the anchor claw basically retracts and cannot complete other anchoring work; 2. There is no anchor claw fixing structure in the structure of the hydraulic anchor itself to complete the locking work of the anchor claw, resulting in structural defects.

[0005] CN107218006A discloses a hydraulic anchor. On the inner circumference of the body, several grooves are evenly distributed in a circle. The depth of the grooves is less than the wall thickness of the body. At least one circular through hole is provided in the groove, and an arc-shaped anchor claw is provided in the circular through hole. The outer surface of the anchor claw is a curved surface and has the same curvature as the curved surface of the body; a limiting plate is provided on the inner surface of the anchor claw. The shape of the limiting plate is the same as the shape of the groove on the body and is located on the same arc surface. A return spring is supported in the cavity formed by the limiting plate and the surface of the groove on the body; a sand control pipe is provided on the inner surface of the limiting plate. The two ends of the sand control pipe are respectively in limit contact with the end faces of the upper joint and the lower joint; several liquid inlet slits with a width of 0.1 - 0.19 mm are provided on the sand control pipe; this hydraulic anchor has no self-locking function and its functions are relatively single.

[0006] Chinese Patent CN204716166U discloses a sealed self-locking hydraulic anchor, which includes an anchoring mechanism, and also includes a sealing mechanism, an anchor releasing mechanism, a self-locking mechanism, and a central pipe. The anchoring mechanism, the sealing mechanism, the self-locking mechanism, and the anchor releasing mechanism are sequentially arranged outside the central pipe from bottom to top. The sealing mechanism is connected to the upper end of the anchoring mechanism. The lower end of the self-locking mechanism is connected to the sealing mechanism, and the upper end of the self-locking mechanism is connected to the anchor releasing mechanism. The central pipe is provided with an upper liquid inlet hole leading to the anchor releasing mechanism, and the central pipe is also provided with a lower liquid inlet hole leading to the self-locking mechanism. The self-locking mechanism includes a sealing joint, a sealing ring, a self-locking shear pin, and a spring. The upper end of the sealing joint is connected to the anchor releasing mechanism by thread, and the lower end is connected to the cylinder sleeve by thread. The upper end of the sealing ring contacts the sealing joint, and the spring is arranged at the lower end. The self-locking shear pin is connected between the sealing ring and the central pipe. The lower end of the spring is positioned on the end platform at the bottom of the upper cylinder cavity. This kind of hydraulic anchor has a complex structure, requires injection of hydraulic oil, has a high use cost, and requires a separate locking mechanism, with cumbersome operation and poor reliability.

[0007] The above-mentioned various traditional hydraulic anchors have various drawbacks and cannot complete some special downhole anchoring operation tasks, resulting in increased production operation costs and reduced operation efficiency. Therefore, there is an urgent need on-site for a special hydraulic anchor to change this situation. Summary of the Invention

[0008] The purpose of the present invention is to provide a hydraulic anchor and its using method in view of the defects existing in the prior art.

[0009] The technical solution of the present invention is: A hydraulic anchor includes a hydraulic anchor barrel, slips, and a slip seat. The slips are radially slidably arranged in the slip grooves of the hydraulic anchor barrel. The slip seat is fixedly installed in the slip seat grooves of the hydraulic anchor barrel. The slips are provided with a plurality of slip teeth, and the slip seat is provided with a plurality of slip holes corresponding to the slip teeth. It also includes a locking shear pin, a pin spring, and a tooth block support spring. Shear pin holes are provided on the side walls of the slip teeth, and locking holes are provided on the inner walls of the slip holes. The locking shear pin and the pin spring are installed in the locking holes, and the locking shear pin is adapted to the shear pin holes. A plurality of spring hole seats are provided at the bottom of the slip seat. The upper ends of the tooth block support springs are located in the spring hole seats, and the lower ends abut against the slips. When the slips are located at the bottom of the slip grooves, the head end of the locking shear pin abuts against the side of the slip teeth. When the slips extend out, the shear pin holes and the locking holes are located on the same straight line, and the locking shear pin enters the shear pin holes.

[0010] Preferably, it further includes an upper joint and a lower plug of the anchor barrel. The lower end of the upper joint is detachably connected to the upper end of the hydraulic anchor barrel, and a through hole is provided at the position of its central axis; the lower plug of the anchor barrel is installed at the lower end of the hydraulic anchor barrel, and the lower plug of the anchor barrel is provided with a central hole; threads are provided on the inner walls of the through hole of the upper joint and the central hole of the lower plug of the anchor barrel. A seat sealing liquid inlet hole communicating with the inner cavity of the hydraulic anchor barrel is provided at the bottom of the slip groove, and a liquid inlet hole communicating with the inner cavity of the hydraulic anchor barrel is provided on the lower plug of the anchor barrel.

[0011] Preferably, the maximum gap between the slips and the slip seat is equal to the maximum anchoring height of the slips, and the height difference between the locking hole and the shear pin hole is equal to the maximum anchoring height of the slips.

[0012] Preferably, a plurality of the spring hole seats are on the same straight line, and this straight line is offset.

[0013] Preferably, two liquid inlet holes are provided on the lower plug of the anchor barrel, and the cross-sectional area of the liquid inlet hole is smaller than the cross-sectional area of the slip teeth.

[0014] Preferably, the upper joint is a special-shaped joint, and a special-shaped groove is provided on the upper end face.

[0015] Preferably, the special-shaped groove is a square groove.

[0016] A using method of a hydraulic anchor includes the following steps:

[0017] 1) Connect this hydraulic anchor with the downhole string, and then lower it into the well. When reaching the predetermined position, stop drilling;

[0018] 2) Pump liquid into the annulus between the tubing and the casing. The liquid enters the inner cavity of the hydraulic anchor barrel through the liquid inlet hole, and then acts on the slips through the seat sealing liquid inlet hole;

[0019] 3) When the pressure reaches a certain value, the liquid will push the slips to move upward;

[0020] 4) When moving upward for a certain distance to meet the anchoring condition, the shear pin hole of the slip teeth is aligned with the locking hole of the slip seat, and the locking shear pin in the locking hole will enter the shear pin hole under the elastic force of the pin spring, and the anchoring self-locking is completed; when the liquid pumping stops, the slip teeth will not reset;

[0021] 5) When the string construction is completed and it needs to be released, block the tubing and pump liquid into the annulus between the tubing and the casing;

[0022] 6) Since the cross-sectional area of a plurality of slip teeth is much larger than the cross-sectional area of the liquid inlet hole of the lower plug of the anchor barrel, when the pressure reaches a certain value, the liquid will push the slips to move downward to cut off the locking shear pin, and the slips are reset;

[0023] 7) When changing the anchoring position, pull out the drill string, replace the locking shear pin, and it can be repeatedly lowered into the well for use.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] This hydraulic anchor changes the traditional locking method of hydraulic anchors. It is internally provided with a self-locking mechanism and does not require the use of other cooperating packers, changing the situation where it can only be anchored by maintaining hydrodynamic force. The anchoring method of this hydraulic anchor is to anchor by applying pressure to the annulus between the tubing and the casing, and the same method of applying pressure to the annulus between the tubing and the casing is used to release the anchor, which is different from the traditional hydraulic anchor. This device can lock the slips at the maximum anchoring height of the slips, effectively improving the reliability of the setting of this hydraulic anchor. This device has a simple structure, is convenient and fast to operate, and has strong reliability, and is suitable for complex downhole operation environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the present invention;

[0027] Figure 2 is a schematic sectional view of the present invention;

[0028] Figure 3 is Figure 2 an enlarged view of part A in

[0029] Figure 4 a schematic structural diagram of the hydraulic anchor barrel;

[0030] Figure 5 a schematic structural diagram of the slips;

[0031] Figure 6 a schematic structural diagram of the slips seat;

[0032] Figure 7 is a schematic sectional view of the slips seat.

[0033] In the figure: 1, upper sub, 101, special-shaped groove, 2, hydraulic anchor barrel, 201, slips groove, 202, slips seat groove, 203, setting fluid inlet hole, 3, lower plug of the anchor barrel, 301, inlet hole, 4, slips, 401, slips teeth, 402, shear pin hole, 5, slips seat, 501, slips hole, 502, locking hole, 503, spring hole seat, 6, locking shear pin, 7, pin spring, 8, tooth block support spring. DETAILED DESCRIPTION OF THE INVENTION

[0034] The following further describes the present invention in conjunction with the drawings and embodiments.

[0035] Embodiment 1

[0036] Refer to Figure 1As shown in the figure, a hydraulic anchor and its usage method include an upper sub 1, a hydraulic anchor barrel 2, a lower plug 3 of the anchor barrel, slips 4, a slips seat 5, a locking shear pin 6, a pin spring 7, and a tooth block support spring 8. The hydraulic anchor barrel 2 is of a cylindrical structure. The lower end of the upper sub 1 is detachably connected to the upper end of the hydraulic anchor barrel 2, and a through hole is provided at the position of its central axis. The lower plug 3 of the anchor barrel is installed at the lower end of the hydraulic anchor barrel 2, and the lower plug 3 of the anchor barrel is provided with a central hole. Threads are provided on the inner walls of the through hole of the upper sub 1 and the central hole of the lower plug 3 of the anchor barrel for butt-joint with downhole tubing.

[0037] Referring Figures 2 - 6 As shown in the figure, three groups of slot holes are arranged in a circumferential array on the outer wall of the hydraulic anchor barrel 2. The lower part of the slot hole is a slips groove 201 adapted to the slips 4, and the upper part is a slips seat groove 202 adapted to the slips seat 5. The slips 4 are slidably arranged radially in the slips groove 201, and the slips seat 5 is fixedly installed in the slips seat groove 202. Two slips teeth 401 are provided on the slips 4, and a shear pin hole 402 is provided at the bottom of the side wall of the slips teeth 401. Two slips holes 501 corresponding to the slips teeth 401 are provided on the slips seat 5, and a locking hole 502 is provided on the inner wall of the slips hole 501. The locking shear pin 6 and the pin spring 7 are installed in the locking hole 502, and the locking shear pin 6 is adapted to the shear pin hole 402. A plurality of spring hole seats 503 are provided at the bottom of the slips seat 5. The upper end of the tooth block support spring 8 is located in the spring hole seat 503, and the lower end abuts against the slips 4. When the slips 4 are located at the bottom of the slips groove 201, the locking shear pin 6 abuts against the side of the slips teeth 401. When the slips 4 extend out, the shear pin hole 402 and the locking hole 502 are located on the same straight line, and the locking shear pin 6 enters the shear pin hole 402. A setting fluid inlet hole 203 communicating with the inner cavity of the hydraulic anchor barrel 2 is provided at the bottom of the slips groove 201, and a fluid inlet hole 301 communicating with the inner cavity of the hydraulic anchor barrel 2 is provided on the lower plug 3 of the anchor barrel.

[0038] During assembly, place the slips 4 in the slips groove 201. First place the pin spring 7 in the locking hole 502 of the slips seat 5, then press and place the locking shear pin 6, and then place the tooth block support spring 8 in the corresponding spring hole seat 503. Then place the slips seat 5 in the slips seat groove 202 and fix the slips seat 5 on the hydraulic anchor barrel 2 with fixing screws. At this time, due to the elastic force of the tooth block support spring 8, there is a certain gap between the slips seat 5 and the slips 4, and this gap is the setting height of the slips seat 5. At this time, the locking shear pin 6 abuts against the side of the slips teeth 401 and cannot enter the shear pin hole 402 of the slips teeth 401.

[0039] Working principle: the hydraulic anchor is connected to the downhole pipe column, and then lowered into the well. When the predetermined position is reached, the drilling is stopped. After the anchoring position is determined, the tubing gate is closed and the casing gate is opened. Liquid is pumped into the oil-casing annulus through the casing gate. The liquid enters the inner cavity of the hydraulic anchor barrel 2 through the liquid inlet hole 301, and then acts on the slip 4 through the seat seal liquid inlet hole 203. With the increase of liquid pressure, when the pressure reaches a certain value, the liquid will move upward against the slip 4. When the upward movement reaches the anchoring condition, the shear pin hole 402 of the slip tooth 401 will face the locking hole 502 of the slip seat 5, and the locking shear pin 6 in the locking hole 502 will enter the shear pin hole 402 under the elastic force of the pin spring 7, thereby realizing the anchoring function of the slip 4. When the pumping of liquid from the casing stops, the slip tooth 401 will not be reset, thereby realizing the function of the hydraulic anchor to anchor the casing without relying on other devices, and then other operations and constructions of the pipe column can be realized.

[0040] When the construction of the downhole pipe string is completed and it needs to be unsealed, the oil pipe string can be lowered to the bottom of the well or the top of the fish, and the bottom of the oil pipe can be temporarily blocked or semi-blocked, and then the casing is pressurized. Since there are six slip teeth 401 on the hydraulic anchor barrel 2, and its cross-sectional area is much larger than the cross-sectional area of ​​the liquid inlet hole 301 of the anchor barrel lower plug 3, due to the pressure difference, when the casing liquid pressure reaches a certain value, the liquid will push the slip 4 downward to shear the locking shear pin 6, and the slip 4 is reset; when changing the anchor position, the drill is pulled out, and the locking shear pin 6 is replaced, and it can be reused in the well. .

[0041] This hydraulic anchor has changed the locking method of traditional hydraulic anchors. It has a self-locking mechanism inside and does not need to use other matching packers, which changes the situation that anchoring can only be achieved by maintaining water dynamics. The anchoring method of this hydraulic anchor is anchoring by pressure-pressing the casing annulus, and the release of anchoring also adopts the pressure-pressing of the casing annulus. This working method is different from the traditional hydraulic anchor. This device has a simple structure, is easy and quick to operate, has strong reliability, and is suitable for complex downhole operating environments.

[0042] Embodiment 2

[0043] Reference Figure 1 As shown, a hydraulic anchor and a method for using the same include an upper joint 1, a hydraulic anchor barrel 2, a lower plug 3 for the anchor barrel, a slip 4, a slip seat 5, a locking shear pin 6, a pin spring 7 and a tooth block support spring 8. The hydraulic anchor barrel 2 is a cylindrical structure. The lower end of the upper joint 1 is detachably connected to the upper end of the hydraulic anchor barrel 2, and a through hole is provided at the center axis position thereof; the lower plug 3 for the anchor barrel is installed at the lower end of the hydraulic anchor barrel 2, and the lower plug 3 for the anchor barrel is provided with a center hole; the inner walls of the through hole of the upper joint 1 and the center hole of the lower plug 3 for the anchor barrel are both provided with threads for docking with a downhole pipe string;

[0044] Reference Figures 2 - 6As shown in the figure, three groups of slot holes are arranged in a circumferential array on the outer wall of the hydraulic anchor cylinder 2. The lower part of the slot hole is a slip groove 201 adapted to the slip 4, and the upper part is a slip seat groove 202 adapted to the slip seat 5. The slip 4 is radially slidably arranged in the slip groove 201, and the slip seat 5 is fixedly installed in the slip seat groove 202. Two slip teeth 401 are provided on the slip 4, and shear pin holes 402 are provided at the bottom of the side wall of the slip teeth 401. Two slip holes 501 corresponding to the slip teeth 401 are provided on the slip seat 5, and locking holes 502 are provided on the inner wall of the slip holes 501. The locking shear pin 6 and the pin spring 7 are installed in the locking hole 502, and the locking shear pin 6 is adapted to the shear pin hole 402. A plurality of spring hole seats 503 are provided at the bottom of the slip seat 5. The upper end of the tooth block support spring 8 is located in the spring hole seat 503, and the lower end abuts against the slip 4. When the slip 4 is located at the bottom of the slip groove 201, the locking shear pin 6 abuts against the side of the slip tooth 401. A setting liquid inlet hole 203 communicating with the inner cavity of the hydraulic anchor cylinder 2 is provided at the bottom of the slip groove 201, and a liquid inlet hole 301 communicating with the inner cavity of the hydraulic anchor cylinder 2 is provided on the lower plug 3 of the anchor cylinder.

[0045] The difference between this embodiment and the first embodiment lies in the settings of the locking hole 502 and the shear pin hole 402. Specifically:

[0046] Refer to Figure 3 As shown in the figure, the maximum gap between the slip 4 and the slip seat 5 is equal to the maximum anchoring height of the slip 4, and the height difference between the locking hole 502 and the shear pin hole 402 is equal to the maximum anchoring height of the slip 4. This setting can lock the slip 4 at the maximum anchoring height of the slip 4, effectively improving the reliability of the seat sealing of this hydraulic anchor.

[0047] Embodiment III

[0048] Refer to Figure 1 As shown in the figure, a hydraulic anchor and its using method include an upper sub 1, a hydraulic anchor cylinder 2, a lower plug 3 of the anchor cylinder, a slip 4, a slip seat 5, a locking shear pin 6, a pin spring 7 and a tooth block support spring 8. The hydraulic anchor cylinder 2 is of a cylindrical structure. The lower end of the upper sub 1 is detachably connected to the upper end of the hydraulic anchor cylinder 2, and a through hole is provided at the central axis position thereof. The lower plug 3 of the anchor cylinder is installed at the lower end of the hydraulic anchor cylinder 2, and the lower plug 3 of the anchor cylinder is provided with a central hole. Threads are provided on the inner walls of the through hole of the upper sub 1 and the central hole of the lower plug 3 of the anchor cylinder for docking with the downhole string.

[0049] Refer to Figures 2 - 6As shown in the figure, three groups of slots are arranged in a circumferential array on the outer wall of the hydraulic anchor cylinder 2. The lower part of the slot is a slip socket 201 adapted to the slip 4, and the upper part is a slip socket seat 202 adapted to the slip socket seat 5. The slip 4 is radially slidably arranged in the slip socket 201, and the slip socket seat 5 is fixedly installed in the slip socket seat 202. Two slip teeth 401 are provided on the slip 4, and shear pin holes 402 are provided at the bottom of the side wall of the slip teeth 401. Two slip holes 501 corresponding to the slip teeth 401 are provided on the slip socket seat 5, and locking holes 502 are provided on the inner wall of the slip holes 501. The locking shear pin 6 and the pin spring 7 are installed in the locking holes 502, and the locking shear pin 6 is adapted to the shear pin holes 402. A plurality of spring hole seats 503 are provided at the bottom of the slip socket seat 5. The upper end of the tooth block support spring 8 is located in the spring hole seat 503, and the lower end abuts against the slip 4. When the slip 4 is located at the bottom of the slip socket 201, the locking shear pin 6 abuts against the side of the slip tooth 401. A seat sealing liquid inlet hole 203 communicating with the inner cavity of the hydraulic anchor cylinder 2 is provided at the bottom of the slip socket 201, and a plurality of liquid inlet holes 301 communicating with the inner cavity of the hydraulic anchor cylinder 2 are provided on the lower plug 3 of the anchor cylinder.

[0050] More specifically, the maximum gap between the slip 4 and the slip socket seat 5 is the maximum anchoring height of the slip 4, and the height difference between the locking holes 502 and the shear pin holes 402 is equal to the maximum anchoring height of the slip 4.

[0051] The difference between this embodiment and the second embodiment lies in the setting of the spring hole seats 503 on the slip socket seat 5. Specifically:

[0052] Refer to Figures 6 - 7 As shown in the figure, three spring hole seats 503 are provided at the bottom of the slip socket seat 5 of this embodiment, and the three spring hole seats 503 are on the same straight line and are offset. The traditional spring hole seats 503 are symmetrically arranged along the center line of the slip socket seat 5, while the arrangement of the spring hole seats 503 in this embodiment is different. This arrangement makes room for the opening of the locking holes 502 and can also achieve the purpose of supporting the slip 4.

[0053] Embodiment Four

[0054] As a preferred embodiment of the present invention, the difference between this embodiment and the third embodiment lies in the setting of the liquid inlet holes 301 on the lower plug 3 of the anchor cylinder. Specifically:

[0055] Two liquid inlet holes 301 are provided on the lower plug 3 of the anchor cylinder, and the cross-sectional area of the liquid inlet holes 301 is smaller than the cross-sectional area of the slip teeth 401. This setting helps the smooth release of this hydraulic anchor.

[0056] Embodiment Five

[0057] As a preferred embodiment of the invention, the difference between this embodiment and the fourth embodiment lies in the structure of the upper joint 1. Specifically:

[0058] Referring to Figure 1 As shown, the upper joint 1 in this embodiment is a special-shaped joint, and a special-shaped groove 101 is provided on the upper end surface, and this special-shaped groove 101 is a square groove; during use, the downhole string is butt-jointed with the upper end of the upper joint 1, and the special-shaped groove 101 provides limit for the downhole string to prevent the downhole string from rotating.

[0059] The present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the gist of the present invention, and the changed content still falls within the protection scope of the present invention.

Claims

1. A hydraulic anchor, comprising a hydraulic anchor barrel, slips and a slip seat. The slips are radially slidably arranged in the slip grooves of the hydraulic anchor barrel. The slip seat is fixedly installed in the slip seat groove of the hydraulic anchor barrel. A plurality of slip teeth are provided on the slips, and a plurality of slip holes corresponding to the slip teeth are provided on the slip seat. It is characterized in that: It also includes a locking shear pin, a pin spring and a tooth block support spring, a shear pin hole is provided on the side wall of the slip tooth, a locking hole is provided on the inner wall of the slip hole, the locking shear pin and the pin spring are installed in the locking hole, and the locking shear pin is adapted to the shear pin hole; a plurality of spring hole seats are provided at the bottom of the slip seat, the upper end of the tooth block support spring is located in the spring hole seat, and the lower end is against the slip; when the slip is located at the bottom of the slip groove, the head end of the locking shear pin is against the side of the slip tooth; when the slip is extended, the shear pin hole and the locking hole are located on the same straight line, and the locking shear pin enters the shear pin hole; It also includes an upper joint and an anchor barrel lower plug, the lower end of the upper joint is detachably connected to the upper end of the hydraulic anchor barrel, and a through hole is provided at the central axis position; the anchor barrel lower plug is installed at the lower end of the hydraulic anchor barrel, and the anchor barrel lower plug is provided with a central hole; the upper joint through hole and the inner wall of the central hole of the anchor barrel lower plug are both provided with threads, the bottom of the slip groove is provided with a seat seal liquid inlet hole connected to the inner cavity of the hydraulic anchor barrel, and the anchor barrel lower plug is provided with a liquid inlet hole connected to the inner cavity of the hydraulic anchor barrel; The maximum gap between the slip and the slip seat is equal to the maximum anchoring height of the slip, and the height difference between the locking hole and the shear pin hole is equal to the maximum anchoring height of the slip; The plurality of spring hole seats are on the same straight line; Two liquid inlet holes are arranged on the lower plug of the anchor cylinder, and the cross-sectional area of ​​the liquid inlet holes is smaller than the cross-sectional area of ​​the slip teeth.

2. The hydraulic anchor according to claim 1, wherein: The upper joint is a special-shaped joint, and a special-shaped groove is arranged on the upper end surface.

3. The hydraulic anchor according to claim 2, wherein: The special-shaped groove is a square groove.

4. A method for using a hydraulic anchor according to any one of claims 1-3, characterized in that, The following steps are involved: 1) Connect the hydraulic anchor to the downhole pipe and then lower it into the well. When it reaches the predetermined position, stop drilling. 2) Pump liquid into the annulus of the oil casing. The liquid enters the inner cavity of the hydraulic anchor barrel through the liquid inlet hole, and then acts on the slips through the seat seal liquid inlet hole; 3) When the pressure reaches a certain value, the liquid will push the slips upward; 4) When the upstream section reaches the anchoring condition, the shear pin hole of the slip tooth is opposite to the locking hole of the slip seat, and the locking shear pin in the locking hole will enter the shear pin hole under the elastic force of the pin spring, and the anchoring self-locking is completed; when the pumping stops, the slip tooth will not reset; 5) When the string construction is completed and needs to be unsealed, plug the oil pipe and pump liquid into the annulus of the oil casing; 6) Since the cross-sectional area of ​​the multiple slip teeth is much larger than the cross-sectional area of ​​the liquid inlet hole of the anchor barrel lower plug, when the pressure reaches a certain value, the liquid pushes the slip downward to shear off the locking shear pin, and the slip is reset; 7) When changing the anchoring position, pull out the drill bit, replace the locking shear pin, and reuse it in the well.

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