A hydraulic anchor for oil field underground operation that is easy to withdraw

Abstract

The present invention discloses a hydraulic anchor for oilfield downhole operations that is easy to withdraw anchors and relates to the technical field of oilfield downhole tools. The anchoring unit comprises: a main body; a plurality of anchoring units, all of which are arranged in the main body, and the anchoring unit comprises: an elliptical slip, which is sealingly and slidably connected in the main body; a mounting seat, which is fixed to the main body, and a connecting frame is fixed to the side of the mounting seat away from the central axis of the main body, and a first elastic member is fixed between the connecting frame and the elliptical slip; a blocking ring, which is arranged on the mounting seat, and the mounting seat is provided with a through hole, and the blocking ring is used to block the through hole on the mounting seat. After the anchoring is completed, the present invention uses the mounting seat and the blocking ring to separate the elliptical slip from the inside of the main body, so as to reduce the influence of the pressure fluctuation inside the main body on the elliptical slip, so that the extrusion force of the elliptical slip on the casing wall remains stable, thereby reducing the probability of casing damage and anchor failure.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield downhole tools, in particular to a hydraulic anchor for oilfield downhole operations that is easy to withdraw. Background Art

[0002] A hydraulic anchor is a tool used to anchor downhole tubing during downhole operations in an oil well. It is mainly composed of a main body, a slip, a pressure plate, a spring and a sealing ring. The slip can be extended and retracted by the pressure difference between the inside and outside of the main body. The side of the slip is provided with ridges to increase the friction between the slip and the casing wall. The pressure plate limits the direction of the slip to prevent the slip from rotating during the extension and retraction process, thereby ensuring that the ridges on the surface of the slip can fully contact the casing wall. During the use of existing hydraulic anchors, they will be affected by factors such as changes in oil layer pressure, failure of the packer, and failure of the surface water injection pump or oil production pump. The impact causes pressure fluctuations inside the main body. When pressure fluctuations occur, the pressure difference between the inside and outside of the hydraulic anchor main body changes, which will change the extrusion pressure of the slip on the casing wall. If the above-mentioned extrusion pressure increases, the extrusion pressure of the slip on the casing wall will be too large, causing casing damage. If the above-mentioned extrusion pressure decreases, the extrusion pressure of the slip on the casing wall will be insufficient, resulting in anchor failure. When the anchor fails, the stability of the downhole tubing will deteriorate, axial movement and radial vibration will occur, the risk of damage to downhole tools will increase, and it will also bring hidden dangers such as leakage, environmental pollution, and safety accidents. Summary of the invention

[0003] The invention provides a hydraulic anchor for oilfield downhole operation which is easy to withdraw, so as to overcome the disadvantages of the existing hydraulic anchor that the casing may be damaged and the anchoring may fail if pressure fluctuation occurs inside the hydraulic anchor during use.

[0004] The technical solution is: a hydraulic anchor for oil field downhole operation that is easy to withdraw, comprising:

[0005] main body;

[0006] A plurality of anchoring units are provided, all of which are provided in the main body, and the anchoring units are used to anchor the main body, and the anchoring units include:

[0007] An elliptical slip is sealingly and slidably connected in the main body;

[0008] A mounting seat is fixedly connected to a side of the main body close to the elliptical slip, a connecting frame is fixedly connected to a side of the mounting seat away from the central axis of the main body, and a first elastic member is fixedly connected between the connecting frame and the elliptical slip;

[0009] A blocking ring is arranged on the mounting seat, the mounting seat is provided with a through hole, the blocking ring is used to block the through hole on the mounting seat, and a second elastic member is fixedly connected between the blocking ring and the connecting frame;

[0010] The monitoring mechanism is arranged on the blocking ring and is used for monitoring the pressure difference between the two sides of the blocking ring and controlling the blocking of the through hole on the mounting seat by the blocking ring.

[0011] Furthermore, a convex ridge is provided on a side of the elliptical slip away from the central axis of the main body, and the maximum distance between the convex ridge of the elliptical slip and the central axis of the main body is equal to the maximum outer diameter of the main body.

[0012] Furthermore, the monitoring mechanism includes:

[0013] A support rod is fixedly connected to the adjacent connecting frame, the support rod is limited and sealingly slidably connected with a monitoring cylinder, the monitoring cylinder is sealingly slidably connected with the adjacent blocking ring, the monitoring cylinder is provided with a U-shaped through hole, and two ports of the U-shaped through hole are respectively located on both sides of the adjacent blocking ring;

[0014] A fixed plate, fixedly connected to the support rod and sealingly sliding in the monitoring tube, a third elastic member is fixedly connected between the fixed plate and the monitoring tube, and the fixed plate is provided with a communication hole;

[0015] The locking assembly is arranged in the adjacent blocking rings and is used to control the movement of the adjacent blocking rings.

[0016] Furthermore, the locking assembly comprises:

[0017] A spring telescopic rod is slidably connected to the blocking ring and contacts the adjacent monitoring tube. The monitoring tube is provided with two unlocking grooves, which are respectively located on both sides of the blocking ring. The unlocking grooves are used for allowing the spring telescopic rod to move. The elastic coefficient of the spring in the spring telescopic rod is smaller than the elastic coefficient of the second elastic member.

[0018] A limit block is fixedly connected to one end of the spring telescopic rod away from the central axis of the blocking ring, a fourth elastic member is fixedly connected between the limit block and the blocking ring, the elastic coefficient of the fourth elastic member is smaller than the elastic coefficient of the spring in the spring telescopic rod, the mounting seat is provided with two annular inclined surfaces, the annular inclined surfaces are used to squeeze the limit block, a limit ring groove is provided in the mounting seat, and the limit block limits the blocking ring through the limit ring groove.

[0019] Furthermore, two extrusion inclined surfaces are arranged on one side of the limit block away from the central axis of the blocking ring, and the extrusion inclined surfaces are used to enable the limit block to quickly enter the limit ring groove.

[0020] Furthermore, it also includes:

[0021] The number of anti-slip plates is equal to that of the elliptical slips, and they are respectively fixed to one side of the adjacent elliptical slips close to the mounting seat. The minimum distance between the anti-slip plates and the central axis of the connecting frame is smaller than the maximum distance between the connecting frame and its central axis.

[0022] Furthermore, it also includes:

[0023] The number of the outer shielding rings is equal to that of the elliptical cava, and both are fixed to the main body. The outer shielding rings are in contact with the adjacent elliptical cava. The side of the elliptical cava close to the mounting seat is fixed with an inner shielding ring, and the inner shielding ring is in contact with the main body.

[0024] Furthermore, there is a gap between the elliptical slip and the adjacent mounting seat.

[0025] Furthermore, it also includes:

[0026] The number of the blocking pieces is twice that of the elliptical slips, and they are fixed to the two sides of the adjacent fixed plates in groups of two through elastic sheets. The blocking pieces are used to block the adjacent connecting holes. Sealing rings are fixed to both sides of the fixed plate near the connecting holes.

[0027] Furthermore, the distance between the two ports on the U-shaped through hole is equal to the length of the blocking ring busbar.

[0028] The beneficial effect of adopting the above technical solution is that after the anchoring is completed, the present invention uses the mounting seat and the sealing ring to separate the elliptical slip from the interior of the main body, thereby reducing the impact of the pressure fluctuation inside the main body on the elliptical slip, so that the extrusion pressure of the elliptical slip on the casing wall remains stable, thereby reducing the probability of problems such as casing damage and anchoring failure.

[0029] The elliptical slip relies on its own shape to keep its moving direction unchanged. During its extension and retraction movement, there is no need to limit it by a pressure plate, thereby reducing the number of gaps at the connection between the elliptical slip and other parts, and reducing the probability of sand and gravel entering the gap near the elliptical slip and causing the elliptical slip to get stuck, thereby facilitating the anchor removal operation.

[0030] A monitoring tube is used to sense the pressure change in the main body. When the pressure changes in the main body, the monitoring tube is slowly moved to slow down the rate at which the pressure change in the main body affects the pressure in the compartment chamber. When the pressure fluctuates in the main body, the amplitude of the pressure change in the compartment chamber caused by the pressure fluctuation in the main body is reduced, and the squeezing force of the elliptical slip on the casing wall is reduced by the pressure fluctuation in the main body, thereby maintaining the stability of the elliptical slip.

[0031] The plugging piece is used to monitor the flow rate of the hydraulic oil through the connecting hole, and then the pressure difference at both ends of the monitoring tube is determined. In this way, the cause of the pressure difference in the main body is determined. When the pressure in the main body changes drastically, the monitoring tube is stopped, and the influence of the main body on the pressure on the elliptical slip is completely isolated, thereby maintaining the anchoring effect of the device on the oil pipe, so that workers have sufficient time to solve the problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0033] Figure 2 It is a schematic diagram of the three-dimensional structure of the elliptical slip and the support rod of the present invention;

[0034] Figure 3 It is a three-dimensional structural cross-sectional view of the main body and the elliptical slip of the present invention;

[0035] Figure 4 It is a three-dimensional structural cross-sectional view of the elliptical slip and the mounting seat of the present invention;

[0036] Figure 5 It is a three-dimensional structural cross-sectional view of the mounting seat, the blocking ring and the monitoring tube of the present invention;

[0037] Figure 6 It is a three-dimensional structural schematic diagram of the support rod and the fixing plate of the present invention;

[0038] Figure 7 It is a three-dimensional structural cross-sectional view of the sealing ring and the limiting block of the present invention;

[0039] Figure 8 It is a three-dimensional structural schematic diagram of the connecting frame and the anti-slip plate of the present invention;

[0040] Fig. 9 It is a three-dimensional structural cross-sectional view of the elliptical slip and the inner shielding ring of the present invention;

[0041] Fig.10 It is a schematic diagram of the three-dimensional structure of the fixing disk, the blocking piece and the sealing ring of the present invention.

[0042] Figure numbers: 1-main body, 2-elliptical cava, 3-mounting seat, 4-connecting frame, 5-first elastic member, 6-sealing ring, 7-second elastic member, 8-support rod, 9-monitoring tube, 901-U-shaped through hole, 10-fixing plate, 101-connecting hole, 11-third elastic member, 12-spring telescopic rod, 121-unlocking groove, 13-limiting block, 131-annular inclined surface, 132-limiting ring groove, 133-extrusion inclined surface, 14-fourth elastic member, 15-anti-slip plate, 16-outer shielding ring, 17-inner shielding ring, 18-sealing piece, 19-sealing ring. DETAILED DESCRIPTION

[0043] The following will be combined with the attached Figure 1 To Attachment Fig.10 The present invention is described in detail, and the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] A hydraulic anchor for oilfield downhole operations that is easy to withdraw, see Figure 1-Figure 4 , including: a main body 1; a plurality of anchoring units, all of which are arranged in the main body 1, the anchoring units are used to anchor the main body 1, and the anchoring units include: an elliptical slip 2, which is sealingly and slidably connected in the main body 1; a mounting seat 3, fixedly connected to a side of the main body 1 close to the elliptical slip 2, a connecting frame 4 is fixedly connected to the side of the mounting seat 3 away from the central axis of the main body 1, and a first elastic member 5 is fixedly connected between the connecting frame 4 and the elliptical slip 2; a blocking ring 6, arranged on the mounting seat 3, the mounting seat 3 is provided with a through hole, the blocking ring 6 is used to block the through hole on the mounting seat 3, and a second elastic member 7 is fixedly connected between the blocking ring 6 and the connecting frame 4; a monitoring mechanism is arranged on the blocking ring 6, for monitoring the pressure difference on both sides of the blocking ring 6, and controlling the blocking of the through hole on the mounting seat 3 by the blocking ring 6; a convex ridge is arranged on the side of the elliptical slip 2 away from the central axis of the main body 1, and the maximum distance between the convex ridge of the elliptical slip 2 and the central axis of the main body 1 is equal to the maximum outer diameter of the main body 1.

[0045] The above scheme aims to solve the problem that when pressure fluctuations occur inside the hydraulic anchor during use, the squeezing force of the slip on the casing wall will change, thereby causing damage to the casing or anchoring failure. After the elliptical slip 2 is anchored, the mounting seat 3 and the blocking ring 6 are used to separate the elliptical slip 2 from the interior of the main body 1, thereby reducing the impact of the pressure fluctuations inside the main body 1 on the elliptical slip 2, so that the squeezing force of the elliptical slip 2 on the casing wall remains stable, thereby reducing the probability of problems such as casing damage and anchoring failure. The number of anchoring units can be adjusted according to the volume of the main body 1. Adjustment is carried out. In this scheme, there are six anchoring units, which are evenly divided into two groups, upper and lower, and each group is equidistantly distributed on the main body 1 in the circumferential direction; the first elastic member 5 can be a tension spring, which is used to provide power for the elliptical cava 2 to retract into the main body 1; the main body 1, the elliptical cava 2, the mounting seat 3 and the sealing ring 6 together constitute a barrier chamber; the second elastic member 7 can be a spring, which is used to maintain the relative position relationship between the sealing ring 6 and the mounting seat 3 (the accompanying drawing shows the relative position of the sealing ring 6 and the mounting seat 3 when the second elastic member 7 is not subjected to force); the upper part of the main body 1 is provided with an internal thread, and the lower part thereof is provided with an external thread, which is used to connect the main body 1 with the oil pipe.

[0046] When the existing hydraulic anchor is applied to an oil well in a sandy formation, gravel will enter the oil pipe and the annulus (i.e., the annular space between the oil pipe and the casing) along with the fluid and be deposited around the slip, and part of the gravel will enter the gap between the slip and the main body and the gap between the slip and the pressure plate, causing the slip to be stuck by the gravel during recovery and unable to be retracted; in this scheme, the elliptical slip 2 is first designed to be elliptical, so that the elliptical slip 2 does not need to be limited by the pressure plate during the extension and contraction process, thereby reducing the number of gaps between the connection between the elliptical slip 2 and other parts, and reducing the probability of gravel entering the gap near the elliptical slip 2 and causing the elliptical slip 2 to be stuck; the maximum distance between the convex edge of the elliptical slip 2 and the central axis of the main body 1 is equal to the maximum outer diameter of the main body 1, which is used to enable the elliptical slip 2 to be completely retracted into the main body 1, reducing the probability of the convex edge on the elliptical slip 2 colliding with external objects during the downward movement of the device, keeping the convex edge on the elliptical slip 2 intact, and thus maintaining the stability of the friction between the elliptical slip 2 and the casing after anchoring.

[0047] See also Figure 3-Figure 6 The monitoring mechanism includes: a support rod 8, which is fixedly connected to the adjacent connecting frame 4. The support rod 8 is limited and sealingly slidably connected with a monitoring tube 9. The monitoring tube 9 is sealingly slidably connected to the adjacent blocking ring 6. The monitoring tube 9 is provided with a U-shaped through hole 901. The two ports of the U-shaped through hole 901 are respectively located on both sides of the adjacent blocking ring 6; a fixed disk 10, which is fixedly connected to the support rod 8 and sealingly slides in the monitoring tube 9. A third elastic member 11 is fixedly connected between the fixed disk 10 and the monitoring tube 9. The fixed disk 10 is provided with a connecting hole 101; a locking assembly is arranged in the adjacent blocking ring 6 for controlling the movement of the adjacent blocking ring 6.

[0048] In the above scheme, the monitoring tube 9 is used to sense the pressure change in the main body 1, and when the pressure change occurs in the main body 1, the monitoring tube 9 is slowly moved to slow down the rate of influence of the pressure change in the main body 1 on the pressure in the interlayer chamber, and then when the pressure fluctuation occurs in the main body 1, the amplitude of the pressure in the interlayer chamber affected by the pressure fluctuation in the main body 1 is reduced, and the extrusion force of the elliptical cava 2 on the casing wall is reduced by the pressure fluctuation in the main body 1, so as to maintain the stability of the elliptical cava 2; initially, the blocking ring 6 is completely located in the through hole of the mounting seat 3, and the through hole of the mounting seat 3 is blocked by the contact between the circumferential side of the blocking ring 6 and the mounting seat 3, and the U-shaped through hole 901 can allow the fluid in the interlayer chamber and the main body 1 to circulate with each other, so as to enable the blocking ring 6 to reset after moving; the third elastic member 11 can be a spring, which is used to keep the fixed disk 10 in the middle of the monitoring tube 9 when it is not under force; hydraulic oil can be stored in the monitoring tube 9, and the movement speed of the monitoring tube 9 when it is affected by the pressure in the main body 1 is slowed down by the flow of hydraulic oil in the connecting hole 101.

[0049] See also Figure 5-Figure 7The locking assembly includes: a spring telescopic rod 12, which is slidably connected to the blocking ring 6 and contacts the adjacent monitoring tube 9. The monitoring tube 9 is provided with two unlocking grooves 121, which are respectively located on both sides of the blocking ring 6. The unlocking grooves 121 are used for the spring telescopic rod 12 to move. The elastic coefficient of the spring in the spring telescopic rod 12 is less than the elastic coefficient of the second elastic member 7; a limit block 13, which is fixedly connected to one end of the spring telescopic rod 12 away from the central axis of the blocking ring 6, and a fourth elastic member 7 is fixedly connected between the limit block 13 and the blocking ring 6. The elastic coefficient of the elastic member 14, the fourth elastic member 14 is smaller than the elastic coefficient of the spring in the spring telescopic rod 12, the mounting seat 3 is provided with two annular inclined surfaces 131, the annular inclined surfaces 131 are used to extrude the limit block 13, a limit ring groove 132 is provided in the mounting seat 3, the limit block 13 limits the blocking ring 6 through the limit ring groove 132; two extrusion inclined surfaces 133 are provided on the side of the limit block 13 away from the central axis of the blocking ring 6, the extrusion inclined surfaces 133 are used to make the limit block 13 quickly enter the limit ring groove 132.

[0050] In the above scheme, the blocking ring 6 is limited by the limit block 13, and the blocking ring 6 is released after the pressure in the main body 1 changes for a period of time (the period of time here refers to: after the monitoring tube 9 is moved by the pressure difference between its two end surfaces, it moves from the initial position to the time required for the unlocking groove 121 on one side to align with the spring telescopic rod 12); the number of the spring telescopic rod 12, the limit block 13 and the fourth elastic member 14 can be changed according to the usage. In this article, the number of the spring telescopic rod 12, the limit block 13 and the fourth elastic member 14 is two; the unlocking groove 121 is composed of a flat surface and an inclined surface, and the depth of the flat surface of the unlocking groove 121 is greater than the length of the limit block 13 protruding out of the blocking ring 6; the fourth elastic member 14 can be a tension spring, and the fourth elastic member 14 can be a tension spring. The four elastic members 14 are initially in a state of storing force, and they always have a tendency to pull the limit block 13 toward the direction of the central axis of the monitoring tube 9. The elastic coefficient of the fourth elastic member 14 is smaller than the elastic coefficient of the spring in the spring telescopic rod 12, and is used to enable the limit block 13 to extend out of the blocking ring 6 under the support of the spring telescopic rod 12 at the initial stage; in the direction of the central axis of the monitoring tube 9, the thickness of the limit block 13 is equal to the width of the limit ring groove 132, and the limit block 13 and the blocking ring 6 are in a non-sealed sliding connection, so that after the limit block 13 is aligned with the limit ring groove 132, the limit block 13 can extend out of the blocking ring 6 and enter the limit ring groove 132; the extrusion inclined surface 133 is used to guide the limit block 13 so that the limit block 13 can easily enter the limit ring groove 132.

[0051] The working principle of the above scheme is as follows: when working underground in an oil well and needing to use the device to anchor the oil pipe, the device is threadedly connected to the oil pipe, and then the device is lowered into the oil well until the main body 1 reaches the specified position. At this time, the oil pipe is pressurized to generate a pressure difference between the inside and outside of the main body 1 (the action of a group of anchoring units at the upper right part of the main body 1 is used as an example to illustrate later), and the pressure in the oil pipe is greater than the pressure in the annulus. At this time, the fluid in the oil pipe pushes the monitoring tube 9 to move right, and the monitoring tube 9 squeezes the hydraulic oil on its left side into its right side through the connecting hole 101, and stretches the first The third elastic member 11, as the monitoring tube 9 moves to the right, the inclined surface of the unlocking groove 121 on the left side gradually contacts the spring telescopic rod 12 (the spring telescopic rod 12, the limit block 13 and the fourth elastic member 14 on the upper side are used as an example for explanation later), and the spring telescopic rod 12 and the limit block 13 begin to move downward under the action of the fourth elastic member 14, so that the lower end of the spring telescopic rod 12 maintains contact with the unlocking groove 121 until the lower end of the spring telescopic rod 12 contacts the flat surface of the unlocking groove 121, at which point the limit block 13 is completely retracted into the blocking ring 6, and the limit on the blocking ring 6 is released.

[0052] After the limit block 13 releases the limit on the sealing ring 6, the sealing ring 6 begins to move right under the push of the fluid pressure in the main body 1, compressing the second elastic member 7 until the sealing ring 6 completely releases the obstruction of the through hole on the mounting seat 3, and the space inside the main body 1 is connected with the interlayer chamber. At this time, the fluid in the main body 1 enters the interlayer chamber and pushes the elliptical cava 2 to move right, stretching the first elastic member 5, so that the elliptical cava 2 gradually protrudes out of the main body 1.

[0053] After the main body 1 is connected with the interlayer chamber, the pressure difference between the left and right sides of the monitoring tube 9 is reduced. At this time, the monitoring tube 9 starts to move left under the action of the third elastic member 11 (the fluid flow rate passing through the mounting seat 3 is low, so it will not hinder the left movement of the monitoring tube 9). The monitoring tube 9 squeezes the hydraulic oil on its right part into its left part through the connecting hole 101. At the same time, the monitoring tube 9 squeezes the spring telescopic rod 12 and the limit block 13 upward through the unlocking groove 121, and stretches the fourth elastic member 14. The limit block 13 re-extends the blocking ring 6 until the spring telescopic rod 12 loses contact with the unlocking groove 121 on the left side, and the spring telescopic rod 12 and the limit block 13 are reset relative to the blocking ring 6. As the monitoring tube 9 moves left, the stretching amount of the third elastic member 11 gradually decreases until the pulling force of the third elastic member 11 on the monitoring tube 9 is balanced with the pressure difference between the left and right sides of the monitoring tube 9, and the monitoring tube 9 stops moving.

[0054] During the process of the fluid in the main body 1 entering the compartment chamber, the elliptical cava 2 gradually protrudes out of the main body 1, and finally the elliptical cava 2 contacts the casing wall. At this time, the elliptical cava 2 stops moving, and the volume of the compartment chamber remains unchanged. As the fluid in the main body 1 continues to enter the compartment chamber, until the pressure in the main body 1 stabilizes and the pressure in the compartment chamber is equal to the pressure in the main body 1, the pressure difference on the left and right sides of the monitoring tube 9 disappears, and the monitoring tube 9 continues to move left under the action of the third elastic member 11, and finally the monitoring tube 9 is reset relative to the blocking ring 6 (the two ports of the U-shaped through hole 901 are respectively located on the left and right sides of the blocking ring 6), and the monitoring tube 9 stops moving; at the same time, the blocking ring 6 moves left under the action of the second elastic member 7, and the blocking ring 6 drives the monitoring tube 9, the spring telescopic rod 12 and the limit block 13 to move together. When the blocking ring 6 moves to contact with the mounting seat 3, The sealing ring 6 blocks the through hole on the mounting seat 3. At this time, the interlayer chamber loses communication with the internal space of the main body 1 again. Subsequently, during the leftward movement of the sealing ring 6, the fluid in the main body 1 enters the interlayer chamber through the U-shaped through hole 901, supplementing the increased volume in the interlayer chamber due to the leftward movement of the sealing ring 6. Subsequently, the limit block 13 contacts the annular inclined surface 131 on the right, and the limit block 13 continues to move with the sealing ring 6. The annular inclined surface 131 on the right squeezes the limit block 13 downward, and the limit block 13 squeezes the spring telescopic rod 12, causing the telescopic end of the spring telescopic rod 12 to shrink. Finally, the limit block 13 retracts into the sealing ring 6 until the sealing ring 6 is reset. Under the action of the spring telescopic rod 12, the limit block 13 again extends out of the sealing ring 6 (the fourth elastic member 14 is stretched and reset again) and limits the sealing ring 6. The anchoring process ends here.

[0055] When it is necessary to release the anchoring and take out the device, the pressure of the fluid in the main body 1 is slowly reduced, and the above anchoring process is repeated in reverse, so that the elliptical slip 2 is finally moved to the left and reset under the action of the first elastic member 5, and the device is pumped out of the oil well through the oil pipe, and the threaded connection between the device and the oil pipe is released.

[0056] When pressure fluctuation occurs in the main body 1, the above-mentioned step of moving the monitoring tube 9 is repeated. If the pressure fluctuation in the main body 1 appears and disappears quickly (for example, pressure fluctuation caused by changes in oil layer pressure), the pressure fluctuation in the main body 1 disappears before the monitoring tube 9 moves to the unlocking groove 121 corresponding to the spring telescopic rod 12. During this pressure fluctuation, the fluid pressure fluctuation in the interlayer chamber is only caused by the movement of the monitoring tube 9, which is the fluctuation of the pressure in the interlayer chamber, so that the change in fluid pressure on the elliptical slip 2 is small, that is, the change in the extrusion pressure of the elliptical slip 2 on the casing wall is small, which reduces the probability of casing damage and anchor failure caused by the elliptical slip 2 due to pressure fluctuations; if the pressure in the main body 1 stabilizes at another pressure value after the fluctuation occurs (for example, pressure fluctuation caused by failure of a surface water injection pump or an oil production pump), the slow movement of the monitoring tube 9 delays the change speed of the extrusion pressure of the elliptical slip 2 on the casing wall, so that the device will not quickly lose the anchoring effect or the extrusion pressure of the elliptical slip 2 on the casing wall will increase, giving the staff time for buffering and remediation.

[0057] See also Figure 2 , Figure 3 , Figure 8 and Fig. 9 , and also includes: anti-slip plates 15, the number of which is equal to the elliptical slips 2, which are respectively fixed to the side of the adjacent elliptical slips 2 close to the mounting seat 3, and the minimum distance between the anti-slip plates 15 and the central axis of the connecting frame 4 is smaller than the maximum distance between the connecting frame 4 and its central axis; outer shielding rings 16, the number of which is equal to the elliptical slips 2, are all fixed to the main body 1, the outer shielding rings 16 are in contact with the adjacent elliptical slips 2, and the side of the elliptical slips 2 close to the mounting seat 3 is fixed with an inner shielding ring 17, and the inner shielding ring 17 is in contact with the main body 1; there is a gap between the elliptical slip 2 and the adjacent mounting seat 3.

[0058] In the above scheme, the anti-slip plate 15 is used to limit the maximum length that the elliptical slip 2 can protrude from the main body 1, thereby reducing the probability of the elliptical slip 2 detaching from the main body 1; the outer shielding ring 16 and the inner shielding ring 17 are used to respectively shield the two gaps at the connection between the elliptical slip 2 and the main body 1, thereby reducing the probability of sand and gravel entering the gap at the connection between the elliptical slip 2 and the main body 1, thereby reducing the probability of the elliptical slip 2 being stuck due to sand and gravel; the outer shielding ring 16 is used to reduce the probability of sand and gravel entering the gap between the side of the elliptical slip 2 close to the annulus and the main body 1, and the inner shielding ring 17 .... The shielding ring 17 is used to reduce the probability of sand and gravel entering the gap between the side of the elliptical cava 2 located in the compartment chamber and the main body 1. The outer shielding ring 16 and the inner shielding ring 17 are both made of high-temperature resistant elastic rubber material, and the outer shielding ring 16 is always in contact with the circumference of the elliptical cava 2, and the inner shielding ring 17 is always in contact with the side wall of the compartment chamber; the gap between the elliptical cava 2 and the adjacent mounting seat 3 is used to temporarily store the sand and gravel remaining in the compartment chamber when the elliptical cava 2 is retracted, thereby reducing the probability that the elliptical cava 2 cannot be completely reset due to the accumulation of sand and gravel in the compartment chamber.

[0059] See also Figure 5 and Fig.10 , and also includes: blocking pieces 18, the number of which is twice that of the elliptical slips 2, and are fixed to the two sides of the adjacent fixed disks 10 in groups of two through elastic sheets, the blocking pieces 18 are used to block the adjacent connecting holes 101, and sealing rings 19 are fixed to both sides of the fixed disk 10 near the connecting holes 101; the spacing between the two ports on the U-shaped through hole 901 is equal to the length of the busbar of the blocking ring 6.

[0060] In the above scheme, the purpose is to use the sealing piece 18 to monitor the flow rate of the hydraulic oil through the connecting hole 101, and then determine the pressure difference at both ends of the monitoring tube 9, so as to determine the cause of the pressure difference in the main body 1 (if the pressure in the main body 1 changes smoothly, it is determined to be actively controlled by the outside world; if the pressure in the main body 1 changes dramatically, it is determined to be caused by an unexpected situation). When the pressure in the main body 1 fluctuates violently, the monitoring tube 9 is stopped, and the influence of the main body 1 on the pressure of the elliptical cava 2 is completely isolated, so as to maintain the anchoring effect of the device on the oil pipe, so that the workers have sufficient time to solve the problem; the sealing piece 18 is made of hard metal, and the sealing ring 19 is made of high-temperature resistant elastic rubber material.

[0061] The working principle of the above scheme is as follows: when the pressure in the main body 1 changes dramatically (the following explanation will be given by taking the reduction of the pressure in the main body 1 as an example), the pressure difference between the left and right end faces of the monitoring tube 9 is large, that is, the pressure difference gives a large acceleration to the movement of the monitoring tube 9, causing the monitoring tube 9 to start to move to the left, and the movement speed of the monitoring tube 9 gradually increases. During the period when the movement speed of the monitoring tube 9 increases, the U-shaped through hole 901 moves to the left, so that the right end of the U-shaped through hole 901 is blocked by the blocking ring 6. At this time, the U-shaped through hole 901 cannot connect the main body 1 with the interlayer chamber. When the movement speed of the monitoring tube 9 reaches a fixed value (at this movement speed, the hydraulic oil can drive the blocking piece 18 to deflect in the process of passing through the connecting hole 101), the hydraulic oil drives the blocking piece 18 on the right side to deflect in the process of passing through the connecting hole 101, causing the elastic piece on the right side of the blocking piece 18 to bend and contact with the corresponding The adjacent sealing ring 19 contacts and blocks the connecting hole 101. At this time, the monitoring cylinder 9 stops moving, but the left and right ends of the monitoring cylinder 9 are still affected by the pressure difference, which makes the monitoring cylinder 9 tend to move to the left. The hydraulic oil in the right part of the monitoring cylinder 9 is squeezed, that is, the hydraulic oil pressure in the right part of the monitoring cylinder 9 increases, and the hydraulic oil pressure in the left part is small, so that there is also a pressure difference on the left and right sides of the sealing ring 19 that blocks the connecting hole 101, so that before the pressure in the main body 1 changes again, the sealing ring 19 can keep the connecting hole 101 blocked. At this time, after the worker monitors the pressure change in the main body 1, he checks the cause of the pressure change and solves it. After the problem is solved, the pressure in the main body 1 is restored, and the sealing piece 18 swings and resets under the action of the adjacent elastic piece, thereby releasing the blockage of the connecting hole 101, and the monitoring cylinder 9 moves right and resets under the action of the pressure difference.

[0062] When it is necessary to release the anchoring, the worker controls the pressure in the main body 1 to decrease slowly and steadily, so that the pressure on the left and right end surfaces of the monitoring cylinder 9 changes smoothly, that is, the movement speed of the monitoring cylinder 9 is low, so that the hydraulic oil will not drive the sealing piece 18 to swing when passing through the connecting hole 101, and the above anchoring process is repeated in reverse, and finally the elliptical cava 2 moves to the left and resets under the action of the first elastic member 5.

[0063] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without creative work should fall within the scope of protection of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention are implemented according to the conventional means in the field unless otherwise specified and limited.

Claims

1. A hydraulic anchor for oilfield downhole operations that is easy to withdraw, characterized in that: include: Subject (1); A plurality of anchoring units are provided, all of which are provided in the main body (1), and the anchoring units are used to anchor the main body (1). The anchoring units include: An elliptical slip (2) is sealingly and slidably connected in the main body (1); A mounting seat (3) is fixedly connected to a side of the main body (1) close to the elliptical slip (2); a connecting frame (4) is fixedly connected to a side of the mounting seat (3) away from the central axis of the main body (1); a first elastic member (5) is fixedly connected between the connecting frame (4) and the elliptical slip (2); a blocking ring (6) arranged on the mounting seat (3); the mounting seat (3) being provided with a through hole; the blocking ring (6) being used to block the through hole on the mounting seat (3); a second elastic member (7) being fixedly connected between the blocking ring (6) and the connecting frame (4); A monitoring mechanism, arranged on the sealing ring (6); The monitoring agencies include: A support rod (8) is fixedly connected to the adjacent connecting frame (4); the support rod (8) is limited in position and sealingly slidably connected to a monitoring tube (9); the monitoring tube (9) is sealingly slidably connected to the adjacent blocking ring (6); the monitoring tube (9) is provided with a U-shaped through hole (901); A fixed plate (10) is fixedly connected to the support rod (8) and slides in a sealed manner in the monitoring tube (9); a third elastic member (11) is fixedly connected between the fixed plate (10) and the monitoring tube (9); and the fixed plate (10) is provided with a communication hole (101); A locking assembly, arranged in the adjacent sealing ring (6); The locking assembly comprises: A spring telescopic rod (12) is slidably connected to the blocking ring (6) and contacts the adjacent monitoring tube (9), wherein the monitoring tube (9) is provided with two unlocking grooves (121); A limit block (13) is fixedly connected to an end of the spring telescopic rod (12) away from the central axis of the blocking ring (6); a fourth elastic member (14) is fixedly connected between the limit block (13) and the blocking ring (6); the mounting seat (3) is provided with two annular inclined surfaces (131); and a limit ring groove (132) is provided in the mounting seat (3).

2. The hydraulic anchor for oilfield downhole operation that is easy to withdraw according to claim 1 is characterized in that: A convex ridge is provided on a side of the elliptical slip (2) away from the central axis of the main body (1), and the maximum distance between the convex ridge of the elliptical slip (2) and the central axis of the main body (1) is equal to half of the maximum outer diameter of the main body (1).

3. The hydraulic anchor for oilfield downhole operation that is easy to withdraw according to claim 1 is characterized in that: The two ports of the U-shaped through hole (901) are respectively located on two sides of the adjacent blocking ring (6).

4. The hydraulic anchor for oilfield downhole operation that is easy to withdraw according to claim 1 is characterized in that: The two unlocking grooves (121) are respectively located on both sides of the blocking ring (6); the elastic coefficient of the spring in the spring telescopic rod (12) is smaller than the elastic coefficient of the second elastic member (7); and the elastic coefficient of the fourth elastic member (14) is smaller than the elastic coefficient of the spring in the spring telescopic rod (12).

5. The hydraulic anchor for oilfield downhole operation that is easy to withdraw according to claim 1 is characterized in that: Two extrusion inclined surfaces (133) are provided on a side of the limit block (13) away from the central axis of the blocking ring (6), and the extrusion inclined surfaces (133) are used to enable the limit block (13) to quickly enter the limit ring groove (132).

6. The hydraulic anchor for oilfield downhole operation according to claim 1 is characterized in that: include: The number of anti-slip plates (15) is equal to that of the elliptical slips (2), and they are respectively fixed to one side of an adjacent elliptical slip (2) close to the mounting seat (3), and the minimum distance between the anti-slip plates (15) and the central axis of the connecting frame (4) is smaller than the maximum distance between the connecting frame (4) and its central axis.

7. The hydraulic anchor for oilfield downhole operation according to claim 6 is characterized in that: include: The number of the outer shielding rings (16) is equal to that of the elliptical cava (2), and both are fixedly connected to the main body (1). The outer shielding rings (16) are in contact with the adjacent elliptical cava (2). The side of the elliptical cava (2) close to the mounting seat (3) is fixedly connected with an inner shielding ring (17), and the inner shielding ring (17) is in contact with the main body (1).

8. The hydraulic anchor for oilfield downhole operation that is easy to withdraw according to claim 7 is characterized in that: There is a gap between the elliptical slip (2) and the adjacent mounting seat (3).

9. The hydraulic anchor for oilfield downhole operation according to claim 7 is characterized in that: include: The number of the blocking pieces (18) is twice that of the elliptical slips (2), and the blocking pieces (18) are fixed to the two sides of the adjacent fixed disks (10) in groups of two by means of elastic sheets. The blocking pieces (18) are used to block the adjacent communicating holes (101), and sealing rings (19) are fixed to both sides of the fixed disk (10) near the communicating holes (101).

10. The hydraulic anchor for oilfield downhole operation that is easy to withdraw according to claim 1 is characterized in that: The distance between the two ports on the U-shaped through hole (901) is equal to the length of the busbar of the blocking ring (6).

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