A downhole tubing cutting device for oil and gas fields with an elastic bladder

Abstract

This invention provides a downhole tubing cutting device for oil and gas fields with an elastic bladder, comprising a main housing, an ignition connector installed in the top of the main housing, and a conductive sealing pin, an ignition assembly, and a gas-producing assembly installed inside the ignition connector; below the gas-producing assembly, a heat-resistant gasket and a piston are installed sequentially from top to bottom inside the main housing; below the piston, an upper pressure nut, a lower pressure nut, and a spring tail connector are installed sequentially from top to bottom inside the main housing, with an elastic bladder tightly pressed between the upper and lower pressure nuts; a circular check valve is installed at the top of the upper pressure nut, and a detonator assembly is installed inside the upper pressure nut. Compared with cutting devices made of rigid materials with a fixed diameter, the downhole tubing cutting device of this invention with an elastic bladder has a higher fit between the elastic bladder and the tubing, thus improving the cutting effect. At the same time, the use of an elastic bladder allows for a variable diameter of the cutting device, improving the efficiency of the cutting operation.

Description

Technical Field

[0001] This invention belongs to the field of downhole accident handling technology for oil and gas wells, and relates to downhole tubing cutting devices, specifically an oil and gas field downhole tubing cutting device with an elastic bladder. Background Technology

[0002] During the exploration and development of oil and gas wells, pipe strings often get stuck. In order to ensure the normal progress of subsequent construction, a cutting device is needed to cut the stuck pipe string. Most existing cutting devices are cylindrical in shape and have a fixed diameter. In actual operation, a cutting device with a matching diameter needs to be selected according to the diameter of the pipe string to be cut.

[0003] The main shortcomings of existing technologies are as follows:

[0004] First, the existing cutting devices have a fixed diameter and are mostly made of rigid materials, so the fit with the tubing is not good enough, which affects the cutting effect.

[0005] Secondly, when cutting tubing, if there is a reduction in diameter inside the tubing, since the diameter of the cutting device is fixed, cutting can only be performed at the upper end of the reduction. Then, a smaller diameter cutting device must be used to cut the remaining section of the tubing at the reduction. After cutting the reduction, a larger diameter cutting device must be used to continue cutting the lower end of the tubing at the reduction. Preparing and changing cutting devices of different diameters during the cutting operation undoubtedly increases the cutting time and reduces the efficiency of the cutting work. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an oil and gas field downhole tubing cutting device with an elastic bladder, which solves the technical problem in the existing technology that the fixed diameter of the cutting device results in insufficient fit with the tubing, thus affecting the cutting effect.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] An oil and gas field downhole tubing cutting device with an elastic bladder includes a main housing, both ends of which are open. A piston is installed inside the main housing. Below the piston, an upper pressure nut, a lower pressure nut, and a spring tail connector are installed sequentially from top to bottom inside the main housing. An elastic bladder is tightly pressed and fixed between the upper pressure nut and the lower pressure nut. Both ends of the upper pressure nut are open. A circular check valve is installed at the top of the upper pressure nut. A detonator assembly is installed inside the upper pressure nut.

[0009] The space enclosed by the bottom end of the piston, the main housing, and the circular check valve is the main charge filling cavity, which is filled with the main charge; the space between the pressure nut on the bladder and the detonator assembly is the main charge flow channel; the elastic bladder near the main charge flow channel has a hole, and the space inside the elastic bladder is the bladder cavity; the main charge filling cavity, the main charge flow channel, and the bladder cavity are connected.

[0010] Both ends of the bladder pressing nut are open, and the space inside the bladder pressing nut is the bladder ejection cavity. After the main charge flows into the bladder cavity through the main charge flow channel, the elastic bladder expands and extends downward and through the bladder ejection cavity. Then the tail connector is ejected and extends out of the bottom of the main shell.

[0011] The present invention also has the following technical features:

[0012] An ignition connector is installed inside the top of the main housing. Both ends of the ignition connector are open. A conductive sealing pin is installed inside the top of the ignition connector. An ignition assembly and a gas generation assembly are installed from top to bottom inside the bottom of the ignition connector. A heat-resistant gasket and a piston are installed from top to bottom inside the main housing below the gas generation assembly. The top surface of the heat-resistant gasket is pressed against the bottom end of the gas generation assembly, and the bottom surface of the heat-resistant gasket is pressed against the top end of the piston.

[0013] The ignition assembly includes an ignition tube seat disposed at the bottom of the ignition connector. The top of the ignition tube seat is closed and the bottom is open. The space inside the ignition tube seat is an ignition chamber containing ignition powder. A conductive spring seat is disposed on the top surface of the ignition tube seat. A conductive spring is installed inside the conductive spring seat. The top of the conductive spring is connected to a conductive sealing pin, and the bottom of the conductive spring is connected to the top surface of the ignition tube seat.

[0014] The gas-generating assembly includes a gas-generating gunpowder shell disposed between the ignition connector and the heat-resistant gasket, with both ends of the gas-generating gunpowder shell open in the axial direction; the space enclosed by the bottom end of the ignition connector, the gas-generating gunpowder shell, and the heat-resistant gasket is a gas-generating chamber, in which gas-generating gunpowder is disposed, with the top end of the gas-generating gunpowder contacting the bottom end of the ignition gunpowder.

[0015] The ignition chamber and the gas-generating chamber are connected, and the overall space formed by the ignition chamber and the gas-generating chamber is a closed space.

[0016] The detonator assembly includes a detonator seat disposed within a nut on the bladder. A piezoelectric inductor is installed in the top of the detonator seat. Below the piezoelectric inductor, a discharge capacitor and an electronic detonator are arranged sequentially from top to bottom within the detonator seat. The top end of the electronic detonator is connected to the discharge capacitor, and the bottom end of the electronic detonator extends into the bladder cavity and contacts the main charge flowing into the bladder cavity. An electronic chip and a battery are disposed on the inner wall of the detonator seat.

[0017] The current output terminal of the piezoelectric element is connected to the first current input terminal of the electronic chip, the second current input terminal of the electronic chip is connected to the battery, the current output terminal of the electronic chip is connected to the current input terminal of the discharge capacitor, the current output terminal of the discharge capacitor is connected to the current input terminal of the electronic detonator, and the bottom end of the electronic detonator is the current output terminal.

[0018] The piston is equipped with multiple sealing rings.

[0019] The ignition connector has a pin clamp nut installed inside the top, and a conductive sealing pin is installed inside the pin clamp nut.

[0020] Compared with the prior art, the present invention has the following technical effects:

[0021] The oil and gas field downhole tubing cutting device of the present invention uses an ignition tube assembly to ignite the gas-producing assembly. The piston moves downward under the pressure of the gas, pressing the main charge into the elastic bladder, causing the elastic bladder to expand until it adheres tightly to the tubing. Compared with cutting devices made of rigid materials with a fixed diameter, the elastic bladder has a higher degree of contact with the tubing, thereby improving the cutting effect.

[0022] Meanwhile, the use of an elastic bladder allows for a variable diameter cutting device, eliminating the need to prepare and replace cutting devices of different diameters during cutting operations, thus reducing cutting time and improving cutting efficiency. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of an oil and gas field downhole tubing cutting device with an elastic bladder.

[0024] Figure 2 A schematic diagram of a cutting operation for a downhole tubing cutting device with an elastic bladder in an oil and gas field.

[0025] Figure 3 This is a schematic diagram of the ignition assembly and the gas generation assembly.

[0026] Figure 4 This is a schematic diagram of the detonator assembly.

[0027] The meanings of the labels in the diagram are as follows: 1-Main shell, 2-Ignition connector, 3-Conductive sealing pin, 4-Ignition assembly, 5-Gas generation assembly, 6-Heat resistant gasket, 7-Piston, 8-Upper pressure nut of the bladder, 9-Lower pressure nut of the bladder, 10-Tail connector, 11-Elastic bladder, 12-Circular check valve, 13-Detonator assembly, 14-Main charge filling chamber, 15-Main charge, 16-Main charge flow channel, 17-Blaze cavity, 18-Blaze ejection chamber, 19-Sealing ring, 20-Pin pressure nut, 21-Column to be cut;

[0028] 401-Ignition tube holder, 402-Ignition chamber, 403-Ignition powder, 404-Conductive spring holder, 405-Conductive spring;

[0029] 501 - Gas-generating gunpowder casing, 502 - Gas-generating gunpowder chamber, 503 - Gas-generating gunpowder;

[0030] 1301-Detonator base, 1302-Piezoelectric inductor, 1303-Discharge capacitor, 1304-Electronic detonator, 1305-Electronic chip, 1306-Battery.

[0031] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, all components, charges, and electronic components in this invention are those known in the art, such as:

[0033] The conductive sealing pin 3 adopts a conductive sealing pin known in the prior art.

[0034] The elastic bladder 11 uses an elastic bladder known in the prior art, which is made of rubber or polyurethane material and has the properties of high temperature resistance and high pressure resistance.

[0035] The circular check valve 12 is a circular check valve known in the prior art, whose blades can only open downwards.

[0036] The main charge 15 uses conventional liquid explosives or plastic explosives known in the prior art.

[0037] Electronic chip 1305 uses conventional electronic chips known in the prior art.

[0038] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0039] Example:

[0040] This embodiment provides a downhole tubing cutting device for oil and gas fields with an elastic bladder, such as... Figure 1 and Figure 2As shown, it includes a main housing 1, which is open at both ends along the axial direction. A piston 7 is installed inside the main housing 1. Below the piston 7, the main housing 1 is equipped with a bladder upper pressure nut 8, a bladder lower pressure nut 9, and a spring tail connector 10, which are installed sequentially from top to bottom. An elastic bladder 11 is tightly pressed and fixed between the bladder upper pressure nut 8 and the bladder lower pressure nut 9. The bladder upper pressure nut 8 is open at both ends along the axial direction. A circular check valve 12 is installed at the top of the bladder upper pressure nut 8. A detonator assembly 13 is installed inside the bladder upper pressure nut 8.

[0041] The space enclosed by the bottom end of piston 7, main housing 1 and circular check valve 12 is the main charge filling cavity 14, which is filled with main charge 15; the space between the pressure nut 8 on the bladder and the detonator assembly 13 is the main charge flow channel 16; the elastic bladder 11 near the main charge flow channel 16 has a hole, and the space inside the elastic bladder 11 is the bladder cavity 17; the main charge filling cavity 14, the main charge flow channel 16 and the bladder cavity 17 are connected.

[0042] Both ends of the bladder pressing nut 9 are open, and the space inside the bladder pressing nut 9 is the bladder ejection cavity 18. After the main charge 15 flows into the bladder cavity 17 through the main charge flow channel 16, the elastic bladder 11 expands and extends downward and penetrates the bladder ejection cavity 18. Then the tail connector 10 is ejected and extends out of the bottom of the main shell 1.

[0043] In this embodiment, the upper pressure nut 8 of the bladder has two functions: the first function is to cooperate with the lower pressure nut 9 of the bladder to fix the elastic bladder 11; the second function is to limit the piston 7 when the piston 7 moves downward.

[0044] In this embodiment, before the cutting operation, the elastic bladder 11 is contracted and folded inside the main housing 1, and the elastic tail connector 10 can protect the elastic bladder 11.

[0045] In this embodiment, the circular check valve 12 ensures that the main charge 15 will not flow back into the main charge filling cavity 14 after flowing into the bladder cavity 17.

[0046] As one specific solution in this embodiment, such as Figure 1 and Figure 2 As shown, an ignition connector 2 is installed inside the top of the main housing 1. Both ends of the ignition connector 2 are open. A conductive sealing pin 3 is installed inside the top of the ignition connector 2. An ignition assembly 4 and a gas generating assembly 5 are installed from top to bottom inside the bottom of the ignition connector 2. A heat-resistant gasket 6 and a piston 7 are installed from top to bottom inside the main housing 1 below the gas generating assembly 5. The top surface of the heat-resistant gasket 6 is pressed against the bottom end of the gas generating assembly 5, and the bottom surface of the heat-resistant gasket 6 is pressed against the top end of the piston 7.

[0047] In this embodiment, the heat-resistant gasket 6 is a conventional heat-resistant gasket known in the prior art. The material of the heat-resistant gasket can be graphite, ceramic, tungsten, or molybdenum. The main function of the heat-resistant gasket 6 is to isolate the high temperature generated by the gas-generating propellant 503 and prevent the piston 7 from being damaged by the high temperature.

[0048] As one specific solution in this embodiment, such as Figure 3 As shown, the ignition assembly 4 includes an ignition tube seat 401 disposed at the bottom of the ignition connector 2. The top end of the ignition tube seat 401 is closed and the bottom end is open. The space inside the ignition tube seat 401 is an ignition chamber 402, and an ignition powder 403 is disposed inside the ignition chamber 402. A conductive spring seat 404 is disposed on the top surface of the ignition tube seat 401. A conductive spring 405 is installed inside the conductive spring seat 404. The top end of the conductive spring 405 is connected to the conductive sealing pin 3, and the bottom end of the conductive spring 405 is connected to the top surface of the ignition tube seat 401.

[0049] In this embodiment, the igniter 403 uses a conventional igniter known in the prior art, and the ignition assembly 4 is used to ignite the gas-generating igniter 503. The conductive spring seat 404 is made of copper, which has good conductivity and can heat up rapidly under the action of current to generate enough heat to ignite the igniter 403.

[0050] As one specific solution in this embodiment, such as Figure 3 As shown, the gas generating assembly 5 includes a gas generating gunpowder housing 501 disposed between the ignition connector 2 and the heat-resistant gasket 6, with both axial ends of the gas generating gunpowder housing 501 being open; the space enclosed by the bottom end of the ignition connector 2, the gas generating gunpowder housing 501, and the heat-resistant gasket 6 is a gas generating chamber 502, in which a gas generating gunpowder 503 is disposed, with the top end of the gas generating gunpowder 503 contacting the bottom end of the ignition gunpowder 403;

[0051] The ignition chamber 402 is connected to the gas-generating chamber 502, and the overall space formed by the ignition chamber 402 and the gas-generating chamber 502 is a closed space.

[0052] In this embodiment, the gas-generating propellant 503 is a known gas-generating propellant in the prior art. The gas-generating propellant 503 is used to generate gas to push the piston 7 downward. The loading amount of the gas-generating propellant 503 needs to be calculated in advance to ensure that the maximum gas pressure it generates is lower than the overall strength of the cutting device. If the gas pressure is too high, it will damage the cutting device, leading to pressure release, water ingress, and failure to work properly.

[0053] As one specific solution in this embodiment, such as Figure 4As shown, the detonator assembly 13 includes a detonator seat 1301 disposed within a pressure nut 8 on the bladder. A piezoelectric inductor 1302 is installed in the top of the detonator seat 1301. Below the piezoelectric inductor 1302, a discharge capacitor 1303 and an electronic detonator 1304 are arranged sequentially from top to bottom in the detonator seat 1301. The top end of the electronic detonator 1304 is connected to the discharge capacitor 1303, and the bottom end of the electronic detonator 1304 extends into the bladder cavity 17 and contacts the main charge 15 flowing into the bladder cavity 17. An electronic chip 1305 and a battery 1306 are disposed on the inner wall of the detonator seat 1301.

[0054] The current output terminal of the piezoelectric inductor 1302 is connected to the first current input terminal of the electronic chip 1305. The second current input terminal of the electronic chip 1305 is connected to the battery 1306. The current output terminal of the electronic chip 1305 is connected to the current input terminal of the discharge capacitor 1303. The current output terminal of the discharge capacitor 1303 is connected to the current input terminal of the electronic detonator 1304. The bottom end of the electronic detonator 1304 is the current output terminal.

[0055] In this embodiment, the detonator assembly 13 is used to detonate the main charge 15.

[0056] As one specific solution in this embodiment, such as Figure 1 and Figure 2 As shown, the piston 7 is provided with multiple sealing rings 19.

[0057] In this embodiment, the sealing ring 19 provided on the piston 7 ensures that the gas generated by the propellant 503 does not leak into the main charge filling cavity 14, preventing the high-temperature gas from causing premature combustion of the main charge 15. Since the piston 7 pushes the main charge 15 to do work, the piston 7 can be made of heat-resistant and high-strength copper or stainless steel to prevent safety accidents.

[0058] As one specific solution in this embodiment, such as Figure 1 and Figure 2 As shown, a pin clamp nut 20 is installed inside the top of the ignition connector 2, and a conductive sealing pin 3 is installed inside the pin clamp nut 20.

[0059] In this embodiment, since the gas-generating gunpowder 503 produces gas after being detonated, the gas will push the conductive sealing pin 3 to move upward, thereby causing the gas of the gas-generating gunpowder to leak. The pin pressing nut 20 can prevent the conductive sealing pin 3 from being pushed by the gas.

[0060] The assembly and operation process of this invention is as follows:

[0061] First, the piston 7, heat-resistant gasket 6, gas generating assembly 5, ignition assembly 4, conductive sealing pin 3, ignition connector 2, and pin pressure nut 20 are installed inside the top of the main housing 1. Then, the main charge 15 is filled into the main charge filling cavity 14. Next, the circular check valve 12, bladder pressure nut 8, elastic bladder 11, bladder pressure nut 9, and spring tail connector 10 are installed inside the bottom of the main housing 1 to complete the assembly of the cutting device.

[0062] Second, the assembled cutting device is placed into the tube column 21 to be cut, and the igniting powder 403 is ignited using an external power input. The ignited igniting powder 403 will ignite the gas-generating powder 503 in a short time. After the gas-generating powder 503 is ignited, the pressure in the gas-generating powder chamber 502 gradually increases. As the pressure rises, the heat-resistant gasket 6 and the piston 7 move downward as a whole, pushing the main charge 15 into the bladder cavity 17.

[0063] Third, after the main charge 15 flows into the bladder cavity 17, the elastic bladder 11 expands and pops off the tail connector 10, extending it out of the bottom of the main shell 1. As the main charge 15 continues to flow in, the elastic bladder 11 continues to expand and its volume continues to increase until the elastic bladder 11 is tightly attached to the column 21 to be cut.

[0064] Fourth, when the piston 7 moves to the circular check valve 12, the piezoelectric inductor 1302 will be subjected to pressure and convert the pressure into a current signal, which is transmitted to the electronic chip 1305. The electronic chip 1305 controls the battery 1306 to quickly charge the discharge capacitor 1303. When the charge reaches the designed capacity, the discharge capacitor 1303 discharges and detonates the electronic detonator 1304, which in turn detonates the main charge 15 of the bladder cavity 17, thus realizing the cutting operation of the column 21 to be cut.

Claims

1. A downhole tubing cutting device for oil and gas fields with an elastic bladder, comprising a main housing (1), wherein both axial ends of the main housing (1) are open, characterized in that, A piston (7) is installed inside the main housing (1); from top to bottom, a bladder upper pressure nut (8), a bladder lower pressure nut (9), and a spring tail connector (10) are installed inside the main housing (1) below the piston (7); an elastic bladder (11) is tightly pressed and fixed between the bladder upper pressure nut (8) and the bladder lower pressure nut (9); both ends of the bladder upper pressure nut (8) are open in the axial direction; a circular check valve (12) is installed at the top of the bladder upper pressure nut (8); and a detonator assembly (13) is installed inside the bladder upper pressure nut (8). The space enclosed by the bottom end of the piston (7), the main housing (1), and the circular check valve (12) is the main charge filling cavity (14), which is filled with the main charge (15); the space between the pressure nut (8) on the bladder and the detonator assembly (13) is the main charge flow channel (16); the elastic bladder (11) near the main charge flow channel (16) has a hole, and the space inside the elastic bladder (11) is the bladder cavity (17); the main charge filling cavity (14), the main charge flow channel (16), and the bladder cavity (17) are connected; Both ends of the bladder pressing nut (9) are open in the axial direction. The space inside the bladder pressing nut (9) is the bladder ejection cavity (18). After the main charge (15) flows into the bladder cavity (17) through the main charge flow channel (16), the elastic bladder (11) expands and extends downward and penetrates the bladder ejection cavity (18). Then the tail connector (10) is ejected and extends out of the bottom of the main shell (1). The main housing (1) is equipped with an ignition connector (2) at the top. Both ends of the ignition connector (2) are open. A conductive sealing pin (3) is installed in the top of the ignition connector (2). An ignition assembly (4) and a gas generating assembly (5) are installed in the bottom of the ignition connector (2) from top to bottom. A heat-resistant gasket (6) and a piston (7) are installed in the main housing (1) below the gas generating assembly (5) from top to bottom. The top surface of the heat-resistant gasket (6) is pressed against the bottom end of the gas generating assembly (5), and the bottom surface of the heat-resistant gasket (6) is pressed against the top end of the piston (7). The ignition assembly (4) includes an ignition tube seat (401) disposed at the bottom of the ignition connector (2). The top end of the ignition tube seat (401) is closed and the bottom end is open. The space inside the ignition tube seat (401) is an ignition chamber (402), and an ignition powder (403) is disposed inside the ignition chamber (402). A conductive spring seat (404) is disposed on the top surface of the ignition tube seat (401). A conductive spring (405) is installed inside the conductive spring seat (404). The top end of the conductive spring (405) is connected to the conductive sealing pin (3), and the bottom end of the conductive spring (405) is connected to the top surface of the ignition tube seat (401). The gas-generating assembly (5) includes a gas-generating gunpowder shell (501) disposed between the ignition connector (2) and the heat-resistant gasket (6), with both ends of the gas-generating gunpowder shell (501) open; the space enclosed by the bottom end of the ignition connector (2), the gas-generating gunpowder shell (501) and the heat-resistant gasket (6) is a gas-generating chamber (502), and a gas-generating gunpowder (503) is disposed in the gas-generating chamber (502), with the top end of the gas-generating gunpowder (503) in contact with the bottom end of the ignition gunpowder (403); The ignition chamber (402) is connected to the gas-generating chamber (502), and the overall space formed by the ignition chamber (402) and the gas-generating chamber (502) is a closed space; The detonator assembly (13) includes a detonator seat (1301) disposed inside a pressure nut (8) on the bladder. A piezoelectric inductor (1302) is installed in the top of the detonator seat (1301). A discharge capacitor (1303) and an electronic detonator (1304) are arranged sequentially from top to bottom in the detonator seat (1301) below the piezoelectric inductor (1302). The top end of the electronic detonator (1304) is connected to the discharge capacitor (1303), and the bottom end of the electronic detonator (1304) extends into the bladder cavity (17) and contacts the main charge (15) flowing into the bladder cavity (17). An electronic chip (1305) and a battery (1306) are disposed on the inner wall of the detonator seat (1301). The current output terminal of the piezoelectric inductor (1302) is connected to the first current input terminal of the electronic chip (1305), the second current input terminal of the electronic chip (1305) is connected to the battery (1306), the current output terminal of the electronic chip (1305) is connected to the current input terminal of the discharge capacitor (1303), the current output terminal of the discharge capacitor (1303) is connected to the current input terminal of the electronic detonator (1304), and the bottom end of the electronic detonator (1304) is the current output terminal.

2. The oil and gas field downhole tubing cutting device with an elastic bladder as described in claim 1, characterized in that, The piston (7) is provided with multiple sealing rings (19).

3. The oil and gas field downhole tubing cutting device with an elastic bladder as described in claim 1, characterized in that, The ignition connector (2) is fitted with a pin clamp nut (20) at the top, and a conductive sealing pin (3) is fitted inside the pin clamp nut (20).

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