Hydraulic anchor with anti-flipper and method of operation thereof

Abstract

This invention relates to a hydraulic anchor and its operating method for preventing anchor claw overturning. The hydraulic anchor includes a hydraulic anchor body, a mandrel, anchor claws, a compression spring, a piston, a one-way ratchet, a one-way blind plug, and a lower connector. An anchor claw is located in the middle of the hydraulic anchor body and is limited by a pressure bar. A compression spring is located between the anchor claw and the pressure bar. A one-way blind plug is located at the lower end of the hydraulic anchor body. The one-way blind plug includes a pressure cap, a blind plug, and a shear pin. The blind plug is installed inside the pressure cap and fixed by the shear pin. The pressure cap is fixedly connected to the hydraulic anchor body, and a through hole is located at the center of the pressure cap. A piston is located between the hydraulic anchor body and the mandrel. Hydraulic oil is filled into the sealed space formed by the hydraulic anchor body, mandrel, and piston. This invention solves the problem of hydraulic anchor failure caused by repeated extension and retraction of the anchor claw during pressurization, and the problem of packer loss due to the inability of the anchor claw to extend and anchor. This invention also solves the problem of anchor claw non-recovery, improving the success rate of packer unsealing.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well operations, and more specifically, to a hydraulic anchor that prevents the anchor claw from overturning and its operation method. Background Technology

[0002] During reservoir stimulation operations in oil and gas wells, high injection rates, high pump pressures, and poor formation communication lead to high pump pressures during construction, causing the hydraulic anchor claws to extend and remain anchored. Once the reservoir is connected, the pressure drops rapidly, reducing or even reversing the internal and external pressure difference at the hydraulic anchor, causing the anchor claws to retract. When the pumping rate is increased, or the formation becomes blocked again, the pressure rises again, and the hydraulic anchor claws extend once more. This repeated pressure reversal causes wear on the O-ring seals at the anchor claws, resulting in leaks in the upper tubing of the packer. In some cases, wear on the O-ring seals can prevent the anchor claws from extending and anchoring during pressurization, leading to packer failure. Existing hydraulic anchors, with their long-term contact with formation fluids, cannot prevent erosion, causing corrosion and jamming. This results in the inability to retract the anchor claws during unsealing operations, ultimately leading to packer unsealing failure. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a hydraulic anchor and its operation method that prevents the anchor claw from overturning. This solves the problem of hydraulic anchor failure caused by repeated extension and retraction of the anchor claw during pressurization, and the problem of packer failure caused by the inability of the anchor claw to extend and anchor. It also solves the problem of anchor claw corrosion and jamming caused by long-term contact between the hydraulic anchor claw and the formation fluid, thus avoiding the problem of the anchor claw being unable to be recovered and improving the success rate of packer release.

[0004] The technical solution adopted by this invention to solve its technical problem is as follows: A hydraulic anchor for preventing anchor claw overturning is constructed, comprising a hydraulic anchor body, a mandrel, an anchor claw, a compression spring, a piston, a one-way ratchet, a one-way blind plug, and a lower connector. An anchor claw is provided in the middle of the hydraulic anchor body, and a pressure bar limits the anchor claw's position. A compression spring is provided between the anchor claw and the pressure bar. A one-way blind plug is provided at the lower end of the hydraulic anchor body. The one-way blind plug includes a pressure cap, a blind plug, and a shear pin. The blind plug is installed inside the pressure cap and fixed by the shear pin. The pressure cap is fixedly connected to the hydraulic anchor body. A through hole is provided at the center of the pressure cap. The diameter of the blind plug is larger than the diameter of the through hole on the pressure cap and smaller than the diameter of the through hole on the hydraulic anchor body. A lower connector is connected to the lower end of the hydraulic anchor body. The mandrel is located inside the hydraulic anchor body. The upper and lower ends of the mandrel are fixedly connected to the hydraulic anchor body and the lower connector, respectively. A piston is provided between the hydraulic anchor body and the mandrel. Hydraulic oil is filled into the sealed space formed by the hydraulic anchor body, the mandrel, and the piston.

[0005] According to the above scheme, the upper end of the hydraulic anchor body is provided with a thread for connecting to the oil pipe, and the lower end of the lower connector is provided with a thread for connecting to the oil pipe.

[0006] According to the above scheme, the inner wall of the piston and the outer wall of the mandrel are provided with matching one-way ratchet teeth.

[0007] According to the above scheme, the mandrel is provided with a pressure transmission hole, which is located at the lower part of the one-way ratchet.

[0008] According to the above scheme, the anchor claw and the hydraulic anchor body are sealed by an "O" ring.

[0009] According to the above scheme, the blind plug and the pressure cap, and the pressure cap and the hydraulic anchor body are respectively sealed by "O" rings.

[0010] According to the above scheme, the hydraulic anchor body and the lower connector, the mandrel and the hydraulic anchor body, and the mandrel and the lower connector are respectively sealed by "O" rings.

[0011] According to the above scheme, the inner wall of the hydraulic anchor body and the outer wall of the mandrel are respectively sealed to the piston by "O" rings.

[0012] The present invention also provides a method for operating the hydraulic anchor that prevents the anchor claw from overturning, comprising the following steps: S1. Inject hydraulic oil into the sealed space formed by the hydraulic anchor body, mandrel, and piston; S2. After the hydraulic anchor passes the ground pressure test, it is connected to the upper part of the hydraulic packer and lowered into the well together with the hydraulic packer. S3. During production and reservoir stimulation, operate in accordance with the standard hydraulic anchor operation procedures; S4. When it is necessary to unseal the packer, pressurize the annulus. The wellhead casing pressure and the annulus fluid column pressure act on the blind plug. When the sum of the wellhead casing pressure and the annulus fluid column pressure is greater than the internal pressure of the blind plug, shear the shear pin, release the wellhead casing pressure, and after the anchor claws are loosened and retrieved, lift the tubing string to unseal the packer.

[0013] The hydraulic anchor and its operation method for preventing anchor claw overturning according to the present invention have the following beneficial effects: 1. This invention designs a blind plug with a diameter larger than the diameter of the through hole on the gland but smaller than the diameter of the through hole on the hydraulic anchor body. When the oil pressure is greater than the sleeve pressure, the hydraulic pressure acts on the blind plug through the through hole on the hydraulic anchor body. Because the diameter of the blind plug is larger than the diameter of the through hole on the gland, the blind plug cannot be displaced, ensuring the sealing of the internal space of the anchor claw. The greater the oil pressure, the greater the hydraulic pressure inside the anchor claw, and the greater the anchoring force of the anchor claw anchored to the inner wall of the sleeve, which greatly improves the stability of this invention. When it is necessary to retract the anchor claw, the annulus is pressurized, and the hydraulic pressure acts on the blind plug through the through hole on the gland. Because the diameter of the blind plug is smaller than the diameter of the through hole on the hydraulic anchor body, the shear pin is cut off, and after the blind plug is knocked off, the internal space of the anchor claw is connected to the annulus, realizing the release of the internal pressure of the anchor claw. Finally, the anchor claw loses its anchoring force, thus facilitating the unsealing of the packer.

[0014] 2. This invention utilizes an O-ring seal to seal the hydraulic anchor body and lower connector, the mandrel and hydraulic anchor body, and the mandrel and lower connector. The sealed space formed by the hydraulic anchor body, mandrel, and piston is filled with hydraulic oil. The O-ring seal prevents hydraulic leakage from the anchor claw, keeping it in an extended anchored state. The hydraulic oil in the sealed space isolates the anchor claw from contact with the formation fluid, preventing impurities from entering the gap between the anchor claw and the hydraulic anchor body. This effectively prevents the anchor claw from being eroded by the formation fluid, preventing rust and jamming, and ensuring the anchor claw can retract normally during packer release operations, thus improving the success rate of packer release. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic diagram of the structure of a hydraulic anchor for preventing anchor claw overturning according to the present invention; Figure 2 yes Figure 1 A magnified view of part A in the diagram; Figure 3 This is a schematic diagram of the piston and one-way ratchet. Explanation of reference numerals in the attached drawings: 1-Hydraulic anchor body; 2-Mandrel; 3-Pressure bar; 4-Anchor claw; 5-Compression spring; 6-Locking screw; 7-One-way blind plug; 7.1-Pressure cap; 7.2-Blind plug; 7.3-Shear pin; 7.4-Through hole on the pressure cap; 7.5-Through hole on the hydraulic anchor body; 8-Piston; 9-One-way ratchet; 10-Pressure transmission hole; 11-Lower connector; 12-"O" ring seal. Detailed Implementation

[0016] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0017] like Figure 1-3As shown, a hydraulic anchor for preventing anchor claw overturning according to the present invention includes a hydraulic anchor body 1, a spindle 2, an anchor claw 4, a compression spring 5, a piston 8, a one-way ratchet 9, a one-way blind plug 7, and a lower connector 11. The upper end of the hydraulic anchor body 1 is provided with a female thread for connecting to an oil pipe. An anchor claw 4 is provided in the middle of the hydraulic anchor body 1. The anchor claw 4 and the hydraulic anchor body 1 are sealed by an O-ring 12. The anchor claw 4 is limited by a pressure strip 3. A compression spring 5 is provided between the anchor claw 4 and the pressure strip 3.

[0018] The lower end of the hydraulic anchor body 1 is provided with a single-flow blind plug 7, which includes a gland 7.1, a blind plug 7.2, and a shear pin 7.3. The blind plug 7.2 is installed inside the gland 7.1 and fixed by the shear pin 7.3. The gland 7.1 is connected to the hydraulic anchor body 1 by threads. The blind plug 7.2 is sealed to the gland 7.1, and the gland 7.1 is sealed to the hydraulic anchor body 1 by O-rings 12. The gland 7.1 has a through hole 7.4 at its center. The diameter of the blind plug 7.2 is larger than the diameter of the through hole 7.4 on the gland but smaller than the diameter of the through hole 7.5 on the hydraulic anchor body.

[0019] When the oil pressure is greater than the sleeve pressure, the hydraulic pressure acts on the blind plug 7.2 through the through hole 7.5 on the hydraulic anchor body. Since the diameter of the blind plug 7.2 is larger than the diameter of the through hole 7.4 on the gland, the blind plug 7.2 cannot be displaced, ensuring the sealing of the internal space of the anchor claw 4. The greater the oil pressure, the greater the hydraulic pressure inside the anchor claw 4, and the greater the anchoring force of the anchor claw 4 anchored to the inner wall of the sleeve, which greatly improves the stability of the invention. When it is necessary to retract the anchor claw 4, the annulus is pressurized, and the hydraulic pressure acts on the blind plug 7.2 through the through hole 7.4 on the gland. Since the diameter of the blind plug 7.2 is smaller than the diameter of the through hole 7.5 on the hydraulic anchor body, the shear pin 7.3 is cut off, and the blind plug 7.2 is knocked off. The internal space of the anchor claw is connected to the annulus, realizing the release of the internal pressure of the anchor claw 4. Finally, the anchor claw 4 loses its anchoring force, thus facilitating the unsealing of the packer.

[0020] The lower end of the hydraulic anchor body 1 is connected to a lower connector 11, and the lower end of the lower connector 11 is provided with a male thread for connecting to the oil pipe.

[0021] The mandrel 2 is located inside the hydraulic anchor body 1. The upper and lower ends of the mandrel 2 are threadedly connected to the hydraulic anchor body 1 and the lower connector 11, respectively. The mandrel 2, the hydraulic anchor body 1, and the lower connector 11 are threadedly connected to each other to form two tension points, which greatly improves the tensile strength of the present invention.

[0022] The hydraulic anchor body 1 and the lower connector 11, the spindle 2 and the hydraulic anchor body 1, and the spindle 2 and the lower connector 11 are sealed by O-rings 12. A piston 8 is provided between the hydraulic anchor body 1 and the spindle 2. The inner wall of the hydraulic anchor body 1 and the outer wall of the spindle 2 are sealed to the piston 8 by O-rings 12. The sealed space formed by the hydraulic anchor body 1, the spindle 2, and the piston 8 is filled with hydraulic oil. The O-rings 12 can prevent hydraulic leakage in the anchor claw 4, keeping the anchor claw 4 in the extended anchored state. The hydraulic oil filled in the sealed space can isolate the anchor claw 4 from contact with the formation fluid, prevent impurities in the formation fluid from entering the gap between the anchor claw 4 and the hydraulic anchor body 1, effectively avoid the anchor claw 4 being eroded by the formation fluid, prevent the anchor claw 4 from rusting and getting stuck, and ensure that the anchor claw 4 can retract normally when the packer is unsealed, thus improving the success rate of packer unsealing.

[0023] The inner wall of piston 8 and the outer wall of spindle 2 are provided with matching one-way ratchet 9. The one-way ratchet 9 is located at the lower end of the "O" seal ring 12. The one-way ratchet 9 prevents piston 8 from retracting after it moves upward under hydraulic pressure, thereby ensuring that the pressure inside anchor claw 4 will not decrease after pressure reversal. That is, the anchoring force of anchor claw 4 is not affected by pressure reversal, thus achieving the purpose of pressure reversal but anchor claw 4 not retracting.

[0024] The spindle 2 is provided with a pressure transmission hole 10, which is located below the one-way ratchet 9.

[0025] The present invention also provides a method for operating a hydraulic anchor to prevent the anchor claw from overturning, comprising the following steps: S1. Inspect the anchor claw 4, single-flow blind plug 7, piston 8 and one-way ratchet 9, and inject hydraulic oil into the closed space formed by the hydraulic anchor body 1, spindle 2 and piston 8.

[0026] S2. After the hydraulic anchor passes the ground pressure test, it is attached to the upper part of the hydraulic packer and lowered into the well together with the hydraulic packer.

[0027] S3. During production and reservoir stimulation, operations shall be carried out in accordance with the standard hydraulic anchor operation procedures.

[0028] S4. When it is necessary to unseal the packer, pressurize the annulus. The wellhead casing pressure and the annulus fluid column pressure act on the blind plug 7.2. When the sum of the wellhead casing pressure and the annulus fluid column pressure is greater than the internal pressure of the blind plug 7.2, shear the shear pin 7.3, release the wellhead casing pressure, wait 60 minutes for the anchor claw 4 to loosen and be retrieved, and then lift the tubing string to unseal the packer.

[0029] The hydraulic anchor for preventing anchor claw overturning and its operation method of the present invention have the following advantages: 1. This invention designs a blind plug with a diameter larger than the diameter of the through hole on the gland but smaller than the diameter of the through hole on the hydraulic anchor body. When the oil pressure is greater than the sleeve pressure, the hydraulic pressure acts on the blind plug through the through hole on the hydraulic anchor body. Because the diameter of the blind plug is larger than the diameter of the through hole on the gland, the blind plug cannot be displaced, ensuring the sealing of the internal space of the anchor claw. The greater the oil pressure, the greater the hydraulic pressure inside the anchor claw, and the greater the anchoring force of the anchor claw anchored to the inner wall of the sleeve, which greatly improves the stability of this invention. When it is necessary to retract the anchor claw, the annulus is pressurized, and the hydraulic pressure acts on the blind plug through the through hole on the gland. Because the diameter of the blind plug is smaller than the diameter of the through hole on the hydraulic anchor body, the shear pin is cut off, and after the blind plug is knocked off, the internal space of the anchor claw is connected to the annulus, realizing the release of the internal pressure of the anchor claw. Finally, the anchor claw loses its anchoring force, thus facilitating the unsealing of the packer.

[0030] 2. The mandrel designed in this invention is located inside the hydraulic anchor body. The upper and lower ends of the mandrel are threadedly connected to the hydraulic anchor body and the lower connector, respectively. The mandrel, the hydraulic anchor body, and the lower connector are threadedly connected to each other to form two tension points, which greatly improves the tensile strength of this invention.

[0031] 3. This invention utilizes O-rings to seal the hydraulic anchor body and lower connector, the mandrel and hydraulic anchor body, and the mandrel and lower connector. The sealed space formed by the hydraulic anchor body, mandrel, and piston is filled with hydraulic oil. The O-rings prevent hydraulic leakage from the anchor claw, keeping it in an extended anchored state. The hydraulic oil in the sealed space isolates the anchor claw from contact with formation fluids, preventing impurities from entering the gap between the anchor claw and the hydraulic anchor body. This effectively prevents the anchor claw from being eroded by formation fluids, preventing rust and jamming, and ensuring the anchor claw can retract normally during packer release operations, thus improving the success rate of packer release.

[0032] 4. The piston inner wall and the mandrel outer wall of the present invention are provided with matching one-way ratchet teeth. The one-way ratchet teeth prevent the piston from retracting after it moves upward under the action of hydraulic pressure, thereby ensuring that the pressure inside the anchor claw will not decrease after the pressure reverses, that is, the anchoring force of the anchor claw is not affected by the pressure reversal, thus achieving the purpose of pressure reversal but anchor claw not retracting.

[0033] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A hydraulic anchor to prevent anchor claw overturning, characterized in that, The device includes a hydraulic anchor body, a mandrel, anchor claws, a compression spring, a piston, a one-way ratchet, a one-way blind plug, and a lower connector. The hydraulic anchor body has anchor claws in the middle, which are limited by a pressure bar. A compression spring is located between the anchor claws and the pressure bar. A one-way blind plug is located at the lower end of the hydraulic anchor body. The one-way blind plug includes a pressure cap, a blind plug, and a shear pin. The blind plug is installed inside the pressure cap and fixed by the shear pin. The pressure cap is fixedly connected to the hydraulic anchor body. A through hole is located at the center of the pressure cap. The diameter of the blind plug is larger than the diameter of the through hole on the pressure cap but smaller than the diameter of the through hole on the hydraulic anchor body. A lower connector is connected to the lower end of the hydraulic anchor body. The mandrel is located inside the hydraulic anchor body, and its upper and lower ends are fixedly connected to the hydraulic anchor body and the lower connector, respectively. A piston is located between the hydraulic anchor body and the mandrel. Hydraulic oil is filled into the sealed space formed by the hydraulic anchor body, the mandrel, and the piston.

2. The hydraulic anchor for preventing anchor claw overturning according to claim 1, characterized in that, The upper end of the hydraulic anchor body is provided with a thread for connecting to the oil pipe, and the lower end of the lower connector is provided with a thread for connecting to the oil pipe.

3. The hydraulic anchor for preventing anchor claw overturning according to claim 1, characterized in that, The inner wall of the piston and the outer wall of the spindle are provided with matching one-way ratchet teeth.

4. The hydraulic anchor for preventing anchor claw overturning according to claim 3, characterized in that, The mandrel is provided with a pressure transmission hole, which is located below the one-way ratchet.

5. The hydraulic anchor for preventing anchor claw overturning according to claim 1, characterized in that, The anchor claw and the hydraulic anchor body are sealed by an "O" ring.

6. The hydraulic anchor for preventing anchor claw overturning according to claim 1, characterized in that, The blind plug and the pressure cap, and the pressure cap and the hydraulic anchor body are respectively sealed by "O" rings.

7. The hydraulic anchor for preventing anchor claw overturning according to claim 1, characterized in that, The hydraulic anchor body and the lower connector, the mandrel and the hydraulic anchor body, and the mandrel and the lower connector are respectively sealed by "O" rings.

8. The hydraulic anchor for preventing anchor claw overturning according to claim 1, characterized in that, The inner wall of the hydraulic anchor body and the outer wall of the mandrel are respectively sealed to the piston by "O" rings.

9. A method for operating the hydraulic anchor with anti-anchor claw overturning as described in claim 1, characterized in that, Includes the following steps: S1. Inject hydraulic oil into the sealed space formed by the hydraulic anchor body, mandrel, and piston; S2. After the hydraulic anchor passes the ground pressure test, it is connected to the upper part of the hydraulic packer and lowered into the well together with the hydraulic packer. S3. During production and reservoir stimulation, operate in accordance with the standard hydraulic anchor operation procedures; S4. When it is necessary to unseal the packer, pressurize the annulus. The wellhead casing pressure and the annulus fluid column pressure act on the blind plug. When the sum of the wellhead casing pressure and the annulus fluid column pressure is greater than the internal pressure of the blind plug, shear the shear pin, release the wellhead casing pressure, and after the anchor claws are loosened and retrieved, lift the tubing string to unseal the packer.

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