Auxiliary device for taking out oil well casing

Abstract

The invention provides an auxiliary device for taking out an oil well casing, relates to the technical field of petroleum engineering well repair, and aims to solve the technical problems that in the prior art, a casing milling tool and a grinding and milling tool are low in casing taking efficiency and long in period, a large number of iron wires and iron chips are generated, well flowback is not thorough, and the environment is polluted. A frequency converter and a heat insulation sleeve are arranged in the shell, the frequency converter is arranged above the heat insulation sleeve, a supporting sleeve is arranged in the heat insulation sleeve, a coil is wound between the supporting sleeve and the heat insulation sleeve, and the coil is connected with the frequency converter through a wire; the guide wheel is arranged on the outer side of the shell; and the guide head is arranged at the bottom end of the shell. The sleeve and set cement outside the sleeve can be rapidly heated, and the sleeve heating device has the advantages of being high in construction operation efficiency, low in operation cost, small in environmental pollution and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of workover in petroleum engineering, and particularly to an auxiliary device for removing oil well casings. Background Art

[0002] During the exploitation of offshore oil and gas resources, while continuously putting new wells into production, a large number of abandoned wells with expired service lives also need to be processed. To ensure safe well sealing and no environmental pollution, it is necessary to remove the casings at a certain depth in the wellbore and then inject cement for plugging.

[0003] Some oil wells have low productivity. To make full use of the wellhead, reduce the well construction cost, and increase the oil well output, sidetracking will be carried out on low-production wells. To increase the size and extension depth of the sidetracked wellbore, it is necessary to remove the casings at a certain depth and then carry out sidetracking.

[0004] Currently, casing removal techniques mostly use milling tools and milling tools. When the central casing and the outer casing are well centered and have a large gap, milling tools are used for casing removal. When milling is unsuccessful, milling tools will be used to grind all the casings into fragments for backflow treatment.

[0005] The applicant of the present invention has found that using milling tools and milling tools for casing removal has low efficiency, a long cycle, and generates a large amount of iron wire and iron filings, resulting in incomplete backflow of the wellbore and environmental pollution problems.

[0006] Therefore, there is an urgent need for an auxiliary device for removing oil well casings to solve the above technical problems. Summary of the Invention

[0007] The purpose of the present invention is to provide an auxiliary device for removing oil well casings to solve the problems in the prior art that using milling tools and milling tools for casing removal has low efficiency, a long cycle, and generates a large amount of iron wire and iron filings, resulting in incomplete backflow of the wellbore and environmental pollution problems. The many technical effects that can be produced by the preferred technical solutions provided by the present invention will be elaborated in detail below.

[0008] To achieve the above purpose, the present invention provides the following technical solutions:

[0009] An auxiliary device for removing oil well casings provided by the present invention includes:

[0010] A housing, inside which an inverter and a heat insulation sleeve are provided. The inverter is arranged above the heat insulation sleeve. A support sleeve is arranged inside the heat insulation sleeve. A coil is wound between the support sleeve and the heat insulation sleeve. The coil is connected to the inverter through a wire.

[0011] A guide head, arranged at the lower part of the housing.

[0012] Guide wheels, arranged on the outside of the housing.

[0013] Preferably, the housing includes:

[0014] A body including a hollow cylindrical structure, and the guide wheel is arranged on the body through a pin shaft;

[0015] A cap connected to the top of the body, and a plurality of interfaces are arranged on the cap for connecting a water outlet pipe, a signal line, an air pipeline, a wire rope, a cable and a water inlet pipe respectively.

[0016] Preferably, the frequency converter includes:

[0017] A frequency modulation circuit, with an inlet connected to the cable and an outlet connected to the wire;

[0018] A signal acquisition circuit connected to the signal line;

[0019] A cooling pipeline connected to the water inlet pipe and the water outlet pipe.

[0020] Preferably, the support sleeve is a hollow cylindrical structure, and a plurality of groups of grooves matching the cross-sectional size of the coil are arranged on the outer side of the support sleeve.

[0021] Preferably, the cross-sectional shape of the coil can be circular, square, rectangular or polygonal.

[0022] Preferably, the coil includes a solid cross-section or a hollow cross-section. When the coil is a hollow cross-section, the coil is connected to the water inlet pipe and the water outlet pipe through the wire.

[0023] Preferably, a plurality of the guide wheels are arranged in a group in the circumferential direction of the body, and a plurality of groups of the guide wheels are arranged in the axial direction of the body.

[0024] Preferably, the guide head is a conical structure, and a ventilation hole is arranged at the center inside the guide head.

[0025] Preferably, a guide cap is further arranged outside the guide head, the guide cap is opposite to the ventilation hole and the bending direction of the guide cap is the same as that of the guide head.

[0026] Preferably, the guide cap is connected to the guide head through a support frame.

[0027] An auxiliary device for removing an oil well casing provided by the present invention includes a housing, an inverter, a heat insulation sleeve, a support sleeve, a coil, a guide head, and a guide wheel. By arranging the guide wheel outside the housing, it is convenient for the device to be lowered into the well; a guide head is arranged at the bottom of the housing to ensure downhole safety; in cooperation with arranging the inverter inside the housing, the casing is heated by high-frequency induction, and the energy conversion efficiency is high, which can effectively heat the casing and the cement sheath outside the casing, destroy the adhesion between the casing and the cement sheath outside the casing, and the operation efficiency is high. And during the operation process, only electric energy is consumed, saving the costs of the milling tools and grinding tools used in the conventional casing removal, greatly shortening the construction period, with low operation cost, and during the electromagnetic induction heating process, no iron wires or iron filings are generated, no drilling fluid circulation is required, and the environmental pollution is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings according to these drawings without creative efforts.

[0029] Figure 1 is a schematic structural diagram of an embodiment of the auxiliary device for removing an oil well casing of the present invention;

[0030] Figure 2 is a schematic diagram of the installation position of the guide wheel in the auxiliary device for removing an oil well casing of the present invention;

[0031] Figure 3 is a schematic structural diagram of the support sleeve in the auxiliary device for removing an oil well casing of the present invention.

[0032] In the figure: 1. Housing; 2. Inverter; 3. Heat insulation sleeve; 4. Support sleeve; 5. Coil; 6. Body; 7. Cap; 8. Guide head; 9. Support frame; 10. Guide cap; 11. Pin shaft; 12. Guide wheel; 13. Wire; 14. Frequency modulation circuit; 15. Signal acquisition circuit; 16. Cooling pipeline; 17. Water outlet pipe; 18. Signal line; 19. Gas pipeline; 20. Steel wire rope; 21. Cable; 22. Water pipe; 23. Groove. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope protected by the present invention.

[0034] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "lateral", "length", "width", "height", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "side", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0035] In the description of the present invention, it should also be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Figure 1 is a schematic structural diagram of this embodiment. As Figure 1 shown, this embodiment provides an auxiliary device for removing an oil well casing, including: a housing 1, a frequency converter 2, a heat insulation sleeve 3, a support sleeve 4, a coil 5, a guide head 8, and a guide wheel 12.

[0037] Specifically, the frequency converter 2, the heat insulation sleeve 3, the support sleeve 4, and the coil 5 are all arranged inside the housing 1. The frequency converter 2 is arranged above the heat insulation sleeve 3. The support sleeve 4 is arranged inside the heat insulation sleeve 3. The coil 5 is wound between the support sleeve 4 and the heat insulation sleeve 3. The coil 5 is connected to the frequency converter 2 through a wire 13. Using the frequency converter 2 can heat the casing by high-frequency induction, with high energy conversion efficiency. It can effectively heat the casing and the cement outside the casing, break the adhesion between the casing and the cement outside the casing, and has high operation efficiency. And during the electromagnetic induction heating process, only electric energy is consumed, saving the costs of the milling tools and grinding tools used in conventional casing removal, and no iron wires or iron filings are generated, and no drilling fluid circulation is required, resulting in less environmental pollution.

[0038] The lower part of the housing 1 in this embodiment is connected with a guide head 8 to ensure downhole safety; a guide wheel 12 is arranged outside the housing 1. The guide wheel 12 is fixed to the housing 1 through a pin shaft 11, facilitating the device to be lowered into the well.

[0039] This auxiliary device for removing oil well casings includes a housing 1, a frequency converter 2, a heat insulation sleeve 3, a support sleeve 4, a coil 5, a guide head 8 and a guide wheel 12. By arranging the guide wheel 12 outside the housing 1, it is convenient for the device to go down the well; by arranging the guide head 8 at the bottom of the housing, the downhole safety is ensured; in cooperation with the frequency converter 2 arranged inside the housing 1, the casing is heated by high-frequency induction, and the energy conversion efficiency is high, which can effectively heat the casing and the cement sheath outside the casing, destroy the adhesion between the casing and the cement sheath outside the casing, and the operation efficiency is high. And during the operation process, only electric energy is consumed, saving the costs of the milling tools and grinding tools used in the conventional casing removal, greatly shortening the construction period, having low operation costs, and during the electromagnetic induction heating process, no iron wires and iron filings are generated, no drilling fluid circulation is required, and the environmental pollution is small.

[0040] As an optional implementation manner, the housing 1 in this embodiment is formed by connecting a main body 6 and a cap 7.

[0041] Among them, the main body 6 is a hollow cylindrical structure, and the guide wheel 12 is arranged on the main body 6 through a pin shaft 11. Specifically, Figure 2 is a schematic diagram of the installation position of the guide wheel in this embodiment. As shown in Figure 1 and Figure 2 shown, a group of multiple guide wheels 12 are arranged in the circumferential direction of the main body 6, and multiple groups of guide wheels 12 are arranged in the axial direction of the main body 6. While facilitating the lowering of this auxiliary device for removing oil well casings, it also ensures the centering of the device in the well, making the construction more convenient and the device more stable in use.

[0042] The cap 7 is connected to the top of the main body 6. In this embodiment, a plurality of interfaces are arranged on the cap 7, which are respectively used to connect a water outlet pipe 17, a signal line 18, a gas pipeline 19, a wire rope 20, a cable line 21 and a water inlet pipe 22.

[0043] As an optional implementation manner, the frequency converter 2 includes a frequency modulation circuit 14, a signal acquisition circuit 15 and a cooling pipeline 16.

[0044] Among them, the inlet of the frequency modulation circuit 14 is connected to the cable line 21, and the outlet of the frequency modulation circuit 14 is connected to the wire 13; the signal acquisition circuit 15 is connected to the signal line 18; the cooling pipeline 16 is connected to the water inlet pipe 22 and the water outlet pipe 17.

[0045] In this arrangement, the alternating current is transmitted to the frequency modulation circuit 14 in the frequency converter 2 via the cable 21. After the frequency modulation circuit 14 steps down the voltage and modulates the frequency, the current enters the coil 5 via the conductor 13, and then returns to the cable 21 via the conductor 13 and the frequency modulation circuit 14. In this process, an alternating magnetic field is generated around the coil 5, and then eddy currents are generated on the sleeve in the magnetic field. The eddy current energy is converted into thermal energy to heat the sleeve, and the sleeve heats the cement stone outside the sleeve through heat transfer. Due to the difference in thermal expansion coefficients between the sleeve and the cement stone, the bonding force between the sleeve and the cement stone is destroyed by the principle of thermal expansion and contraction.

[0046] The signal acquisition circuit 15 in the frequency converter 2 collects the working parameters such as voltage, current, temperature, etc. in the frequency modulation circuit 14, and transmits them to the ground control console through the signal line 18 after specific encoding, so that the operator can control the progress of the operation.

[0047] Cold water enters the cooling pipeline 16 in the inverter 2 through the water inlet pipe 22, cools the entire inverter 2 through heat exchange, and the heated hot water returns to the ground through the water outlet pipe 17, ensuring that the inverter 2 does not overheat and can work normally.

[0048] As an optional implementation, Figure 3 Schematic diagram of the structure of the support sleeve in this embodiment. Figure 3 As shown, the support sleeve 4 is a hollow cylindrical structure, and a plurality of groups of grooves 23 matching the cross-sectional dimensions of the coil 5 are provided on the outer side of the support sleeve 4 for limiting the position of the coil 5 to ensure safety and stability during use.

[0049] The cross-sectional shape of the coil 5 in this embodiment can be circular, square, rectangular or polygonal, and can be a solid cross-section or a hollow cross-section. When the coil 5 is a hollow cross-section, the coil 5 is connected to the water inlet pipe 22 and the water outlet pipe 17 through the wire 13.

[0050] With such arrangement, when the coil 5 is a hollow cross-section, a portion of the cold water in the water inlet pipe 22 will enter the coil 5 through the hollow conductor 13 to cool the coil 5, and the heated hot water will return to the ground through the hollow conductor 13 and the water outlet pipe 17.

[0051] As an optional embodiment, the guide head 8 is a conical structure, and a vent hole is provided at the inner center of the guide head 8. In this embodiment, a guide cap 10 is also provided outside the guide head 8, and the guide cap 10 is directly opposite to the vent hole and the bending direction of the guide cap 10 and the guide head 8 are consistent.

[0052] Specifically, in this embodiment, a guide cap 10 is provided to be connected to the guide head 8 via a support frame 9 .

[0053] The inert gas enters the internal part of the downhole heating casing high-frequency induction device through the gas pipeline 19, and then discharges through the middle ventilation hole of the guiding head 8. Due to the guiding effect of the inner curved surface of the guiding cap 10, the discharged gas turns upward, diluting and carrying out the hydrocarbon gas cracked from the oil stain on the inner wall of the casing during the heating process, effectively avoiding the accumulation of hydrocarbon gas, shielding the contact between the hydrocarbon gas and oxygen at high temperature, preventing combustion and explosion, and ensuring downhole safety.

[0054] The working process of this embodiment is as follows:

[0055] The auxiliary device for taking out this oil well casing is lowered to the target depth in the casing through the steel wire rope 20. Since multiple groups of guide wheels are arranged outside the shell 1, it is convenient for the downhole heating casing high-frequency induction device to be lowered, and at the same time, it ensures the centering of the downhole heating casing high-frequency induction device in the well;

[0056] The alternating current is transmitted to the frequency modulation circuit 14 in the frequency converter 2 through the cable 21. After being stepped down and frequency modulated by the frequency modulation circuit 14, the current enters the coil 5 through the wire 13, and then returns to the cable 21 through the wire 13 and the frequency modulation circuit 14; during this process, an alternating magnetic field is generated around the coil 5, and then eddy currents are generated on the casing within the magnetic field. The eddy current energy is converted into heat energy to heat the casing, and the casing heats the cement sheath outside the casing through heat transfer. Due to the difference in the thermal expansion coefficients of the casing and the cement sheath, the adhesion between the casing and the cement sheath is destroyed through the principle of thermal expansion and contraction;

[0057] The cold water enters the cooling pipeline 16 in the frequency converter 2 through the water inlet pipe 22, cools the entire frequency converter 2 through heat exchange, and the heated hot water returns to the ground through the water outlet pipe 17; ensuring that the frequency converter 2 does not overheat and can work normally;

[0058] The inert gas enters the internal part of the downhole heating casing high-frequency induction device through the gas pipeline 19, and then discharges through the middle ventilation hole of the guiding head 8. Due to the guiding effect of the inner curved surface of the guiding cap 10, the discharged gas turns upward, diluting and carrying out the hydrocarbon gas cracked from the oil stain on the inner wall of the casing during the heating process, effectively avoiding the accumulation of hydrocarbon gas, shielding the contact between the hydrocarbon gas and oxygen at high temperature, preventing combustion and explosion, and ensuring downhole safety;

[0059] The signal acquisition circuit 15 in the frequency converter 2 collects the working parameters such as voltage, current, and temperature in the frequency modulation circuit 14, and after specific encoding, transmits them to the ground console through the signal line 18, facilitating the operator to control the operation progress;

[0060] When the coil 5 has a hollow cross-section, a part of the cold water in the water inlet pipe 22 will enter the coil 5 through the hollow wire 13 to cool the coil 5, and the heated hot water will then return to the ground through the hollow wire 13 and the water outlet pipe 17;

[0061] The device is moved from the well bottom towards the wellhead through the wire rope 20, continuously heating the casing and the cement sheath outside the casing to destroy the bonding force between the casing and the cement sheath, thereby facilitating the later removal operation of the casing.

[0062] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the said claims.

Claims

1. An auxiliary device for removing oil well casing, characterized in that: include: A housing (1) is provided with a frequency converter (2) and a heat insulating sleeve (3) therein; the frequency converter (2) is arranged above the heat insulating sleeve (3); a support sleeve (4) is arranged inside the heat insulating sleeve (3); a coil (5) is wound between the support sleeve (4) and the heat insulating sleeve (3); and the coil (5) is connected to the frequency converter (2) via a wire (13); A guide head (8) is arranged at the lower part of the housing (1); The guide wheel (12) is arranged on the outside of the housing (1).

2. The auxiliary device for removing casing from an oil well according to claim 1, characterized in that: The housing (1) comprises: The body (6) comprises a hollow cylindrical structure, and the guide wheel (12) is arranged on the body (6) via a pin shaft (11); A cover cap (7) is connected to the top of the body (6), and a plurality of interfaces are arranged on the cover cap (7), which are respectively used to connect a water outlet pipe (17), a signal line (18), an air pipe line (19), a steel wire rope (20), an electric cable (21) and a water inlet pipe (22).

3. The auxiliary device for removing casing of an oil well according to claim 2, characterized in that: The frequency converter (2) comprises: A frequency modulation circuit (14), the inlet of which is connected to the cable (21), and the outlet of which is connected to the wire (13); A signal acquisition circuit (15) connected to the signal line (18); The cooling pipeline (16) is connected to the water inlet pipe (22) and the water outlet pipe (17).

4. An auxiliary device for removing oil well casing according to any one of claims 1 to 3, characterized in that: The support sleeve (4) is a hollow cylindrical structure, and a plurality of groups of grooves (23) matching the cross-sectional dimensions of the coil (5) are arranged on the outer side of the support sleeve (4).

5. An auxiliary device for removing casing from an oil well according to any one of claims 1 to 3, characterized in that: The cross-sectional shape of the coil (5) can be circular, square, rectangular or polygonal.

6. An auxiliary device for removing casing from an oil well according to claim 2 or 3, characterized in that: The coil (5) includes a solid section or a hollow section. When the coil (5) is a hollow section, the coil (5) is connected to the water inlet pipe (22) and the water outlet pipe (17) through the wire (13).

7. An auxiliary device for removing oil well casing according to claim 2 or 3, characterized in that: A group of multiple guide wheels (12) are arranged in the circumferential direction of the body (6), and multiple groups of guide wheels (12) are arranged in the axial direction of the body (6).

8. An auxiliary device for removing casing from an oil well according to any one of claims 1 to 3, characterized in that: The guide head (8) is a conical structure, and a vent hole is arranged at the inner center of the guide head (8).

9. The auxiliary device for removing casing of an oil well according to claim 8, characterized in that: A guide cap (10) is also provided on the outside of the guide head (8), the guide cap (10) is directly opposite to the vent hole and the bending direction of the guide cap (10) is consistent with that of the guide head (8).

10. The auxiliary device for removing casing of an oil well according to claim 9, characterized in that: The guide cap (10) is connected to the guide head (8) via a support frame (9).

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