Underground electric heating wax removal tools

Abstract

The present invention relates to an underground electric heating wax removal tool suitable for wireline or cable operations. The tool comprises an upper joint, an intermediate cylinder, and an electric heating head, which are sequentially connected to form an externally sealed internal space. The internal space accommodates a power supply assembly. The outer periphery of the electric heating head is a rotating surface, and the lower portion is provided with at least two blades with downwardly pointed cutting edges and an outer periphery rotating surface. The blades are distributed along the circumference of the electric heating head and are separated from each other. A channel is left between the blades to allow wax removal debris to pass through. An electric heating element is embedded in the blades. The electric heating element is connected to the power supply assembly by a wire passing through a hole in the electric heating head. The hole is sealed. When used in wireline operations, the tool is powered by a battery. The present invention can be lowered into underground pipelines including oil pipes and casings using wireline or cable operation equipment to directly heat the blades of the mechanical wax removal device. The heat dissolves the wax deposits while mechanically cutting, thereby overcoming the problem that pure mechanical wax removal is difficult to remove when the wax deposits are thick and that the wax scraper is easily stuck. At the same time, there is no chemical pollution.

Description

Technical Field

[0001] The invention relates to the field of oil and gas resource exploitation, and in particular to an underground electric heating wax removal tool for removing wax deposited on the inner wall of an underground pipeline. Background Art

[0002] During oilfield production, deposits easily form inside pipelines such as tubing and casing. Wax deposits are the most common. Wax deposits can reduce the inner diameter of the pipeline, hindering oil flow and even blocking it, thereby impacting well production and operational efficiency. Therefore, mechanical, thermal, and chemical wax removal techniques are commonly used to remove wax deposits from the inner walls of downhole production pipelines. Each of these wax removal techniques has its own advantages and disadvantages.

[0003] Mechanical wax removal, which uses a wire-driven mechanical wax scraper to clean the pipe wall, has the advantage of good wax removal effect and can directly physically remove impurities; the disadvantage is that the wax removal process may cause damage to the pipe string, especially when the wax is very thick, which can easily cause it to get stuck or even cause a fall into the well.

[0004] Electric wax removal uses an electric current to heat the tubing, dissolving the wax and discharging it with the wellbore fluid, thereby removing oil, wax, and impurities from the tubing. Advantages include effective wax removal and a wide range of applications. Disadvantages include the high energy consumption and the need for specialized equipment fixed to the wellhead.

[0005] Chemical wax removal removes wax and impurities from the tubing string by adding a wax remover to break down the wax. Advantages include fast wax removal, which can be enhanced by adding an appropriate wax remover. Disadvantages include toxic wax removers, environmental pollution, and high costs.

[0006] In current production practice, there is an urgent need for a wax removal tool that can be lowered into the well through steel wire or cable operating equipment, can handle thicker wax deposits, consumes less energy, and is pollution-free. Summary of the Invention

[0007] The main idea of ​​the present invention is to propose a downhole electric thermal wax removal tool that combines mechanical and electric thermal wax removal methods. The tool comprises an upper joint, a power supply assembly, and an electric heating head, or an intermediate cylinder. The upper joint is connected to the electric heating head, or the upper joint, the intermediate cylinder, and the electric heating head are connected in sequence to form an externally sealed internal space. The internal space accommodates the power supply assembly. The tool is characterized by:

[0008] The outer periphery of the electric heating head is a rotating surface with an inner cavity, the upper end of which is connected to an upper joint or an intermediate cylinder, and the lower part is provided with at least two blades with downward-pointing blade tips and an outer periphery of the rotating surface; the at least two blades are distributed along the circumference of the electric heating head and are separated from each other, and a channel is left between the blades to allow wax cleaning debris to pass through with the fluid;

[0009] The blade is embedded with an electric heating element for heating the blade;

[0010] The electric heating element is connected to a wire, and the wire passes through a hole provided in the electric heating head and enters the internal space to be connected to the power supply component; the hole is sealed.

[0011] In a preferred embodiment of the present invention, the power supply component includes a battery pack or a delay control device at the same time; the delay control device is connected between the electric heating body and the battery pack; the battery pack includes at least three battery cells, which are connected end to end in series.

[0012] In a preferred embodiment of the present invention, the delay control device includes a mechanical timer and a micro switch, and two ends of a group of contacts of the micro switch are respectively connected to the electric heating body and the battery pack.

[0013] In a preferred embodiment of the present invention, the delay control device includes a delay switch composed of electronic components, and the delay switch is respectively connected to a battery pack and the electric heating element.

[0014] In a preferred embodiment of the present invention, the power supply component includes a temperature control circuit, a temperature sensor is embedded in the electric heating head or the blade, and a wire with an insulating jacket passes through the hole of the electric heating head to connect the temperature sensor embedded in the blade to the temperature control circuit.

[0015] In a preferred embodiment of the present invention, each blade is embedded with both an electric heater and a temperature sensor; the temperature control circuit includes multiple independent temperature control loops; each loop is respectively connected to a temperature sensor and an electric heater located on a different blade, independently detects the temperature of the blade to which it is connected, and controls the current of the electric heater in the blade according to the temperature.

[0016] In a preferred embodiment of the present invention, the outer side of the blade tip has an inward chamfer.

[0017] In a preferred embodiment of the present invention, the upper connector is a cable upper connector with a central through hole, and a cable connector is installed at the upper end of the central through hole; the power supply component includes a temperature control circuit, the blade has a temperature sensor, and a wire with an insulating jacket passes through the hole of the electric heating head to connect the temperature sensor to the temperature control circuit.

[0018] In a preferred embodiment of the present invention, the power supply assembly includes a splitter but does not include a temperature control circuit, and the blade does not have a temperature sensor; the splitter is connected to the cable connector and the electric heating element respectively.

[0019] In a preferred embodiment of the present invention, the electric heating head or the blade is made of copper alloy.

[0020] The downhole electric heating wax removal tool provided by the present invention has the following beneficial effects:

[0021] The technical solution proposed by the present invention combines mechanical wax cleaning with electric wax cleaning. A steel wire or cable downhole operation device can be lowered into the downhole pipeline, including the oil pipe and casing, and the blade of the mechanical wax cleaning device is directly heated by electric heat. The thermal dissolution of wax deposits occurs during mechanical cutting, overcoming the problem of pure mechanical wax cleaning being difficult to remove when the wax deposits are thick and causing the wax scraper to get stuck easily. There is no chemical pollution. Multiple blades are used to increase the length of contact between the cutting edge and the wax deposits during cutting, thereby accelerating the cutting speed. Because the blades are separated from each other and have gaps, the blades can bend and deform elastically to adapt to the uneven inner wall of the pipeline. Furthermore, a channel is left between the blades, away from the blade tip, to allow wax debris to pass through with the fluid, facilitating the flow of wax debris cut by the blades with the well fluid, and facilitating the discharge of wax debris with the well fluid to the wellhead. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall appearance of one embodiment of the present invention.

[0023] Figure 2 yes Figure 1 Section view along AA.

[0024] Figure 3 yes Figure 2 A partial magnified view of the middle Y region.

[0025] Figure 4 yes Figure 2 A partial magnified view of the middle X area.

[0026] Figure 5 yes Figure 2 A partial enlarged view of the middle W area.

[0027] Figure 6 yes Figure 2 A local magnified view of the middle V area.

[0028] Figure 7 It is an overall three-dimensional diagram of an electric heating head according to one embodiment of the present invention.

[0029] Figure 8 This is a front view of an electric heating head according to one embodiment of the present invention.

[0030] Figure 9 yes Figure 8 Cross-sectional view along BB.

[0031] Figure 10 yes Figure 8 Top view of .

[0032] Figure 11 yes Figure 9A local magnified view of the middle Z region.

[0033] Figure 12 It is a schematic diagram of the overall appearance of one embodiment of the present invention.

[0034] Figure 13 yes Figure 12 Cross-sectional view along DD.

[0035] In the figure: 1. Upper connector; 2. Intermediate tube; 3. Electric heating head; 301. Inner cavity of electric heating head; 4. Blade; 5. Battery cell; 501. Positive electrode of battery cell; 502. Negative electrode of battery cell; 6. Delay / temperature control circuit; 601. Circuit element; 602. Circuit board; 7. Insulation seat of battery pack; 8. Electric heating element; 9. Temperature sensor; 8a. Electric heating element slot; 9a. Temperature sensor slot; 8b. Electric heating element wire hole; 9b. Temperature sensor wire hole; 10. Electric heating element connecting wire; 11. Temperature sensor connecting wire; 12. Circuit positive busbar; 13. Positive electrode jack; 14. Positive electrode pin; 15. Positive busbar of battery pack; 16. Insulating pads between battery cells; 17. Connecting wires between battery cells; 18. Negative busbar of battery pack; 19. Shock absorber seat of battery pack; 20. Negative busbar pin of battery pack; 21. Negative grounding jumper; 22. Negative grounding screw; 23. Negative grounding jack; 24. Grounding jack buffer seat; 25. Grounding jack buffer spring; 26. Shock absorber spring of battery pack; 31. Cable upper connector; 32. Cable intermediate barrel; 33. Cable core wire; 34. Cable ground wire; 35. Cable connector; 36. Cable temperature control circuit; 37. Cable connector insulating seat. Implementation Method

[0036] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now listed.

[0037] The specific embodiments of the present invention described herein are only used to explain the purpose of the present invention and are not to be understood as limiting the present invention in any way. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiment. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items. The word "waxing" used herein can be a verb, depending on the context, indicating the action of wax depositing on the inner wall of the pipe, or a noun indicating wax deposited on the inner wall of the pipe, to specifically refer to wax condensed and deposited on the inner wall of the pipe rather than ordinary wax.

[0038] The first embodiment of the downhole electric thermal wax removal tool proposed by the present invention comprises an upper joint, an intermediate tube, and an electric heating head connected sequentially from top to bottom. The upper joint, intermediate tube, and electric heating head are connected to form an externally sealed internal space, and the connection between the three is sealed by a threaded connection and a double O-ring rubber seal. The internal space houses the power supply assembly, which includes a battery pack or a delay control device. The battery pack includes at least three battery cells 5 connected end to end in series.

[0039] Among them, the upper joint is used to connect the weighted rod and wire tools such as the rope cap upwards. The rope cap connects the wire to the ground. The wire drives the entire wax cleaning tool up and down to clean the wax on the inner wall of the pipe; the electric heating head is used to cut and scrape off the wax on the inner wall of the pipe.

[0040] The outer periphery of the electric heating head is a rotating surface. The electric heating head has an inner cavity, and the outer diameter is smaller than the inner diameter of the pipe to be dewaxed, so it can just be lowered into the pipe. The upper end of the electric heating head is connected to the middle tube, and the lower part is provided with at least two blades with downward-pointing blade tips and a rotating outer periphery. The at least two blades are distributed along the circumference of the electric heating head and are separated from each other. A channel is left between the blades to allow wax removal fragments to pass through with the fluid. Multiple blades increase the length of contact between the cutting edge and the wax during cutting, thereby speeding up the cutting speed; the blades are separated from each other, leaving a gap, so that the blades can bend and deform elastically to adapt to the uneven inner wall of the pipe. A channel is left between the blades, which is away from the blade tip and allows wax removal fragments to pass through with the fluid, so that the wax fragments cut off by the blades can flow through with the well fluid, further flow to the wellhead with the well fluid, and finally be discharged from the wellhead.

[0041] An electric heater is embedded in the blade to heat the blade. The electric heater is embedded in the blade and is in direct contact with the blade. The heat emitted by the electric heater is fully transferred to the blade, making maximum use of the limited energy stored in the battery pack. The blade is heated to melt the wax or at least soften it, making it easier to peel off from the inner wall of the pipe. The electric heater is connected to a wire with an insulating outer layer, which passes through the hole of the electric heating head and is connected to the delay control device, which is further connected to the battery pack. The hole is sealed to prevent harmful substances in the high-pressure environment underground from invading the external sealed space formed by the connection of the upper joint, the intermediate cylinder and the electric heating head, and causing damage to the battery pack or the delay control device.

[0042] When the power supply assembly accommodated in the internal space includes both a battery pack and a delay control device, the delay control device is connected between the battery pack and the electric heating element to delay the battery pack from supplying power to the electric heating element. The purpose of delaying the battery pack from supplying power to the electric heating element is to reserve enough time for the downhole electric heating wax removal tool to reach the wax-covered position in the well before starting to heat. Firstly, it is to save battery power; secondly, it is to prevent the electric heating head from heating to high temperatures and damaging the wellhead sealing rubber parts used in wireline operations. The delay control device can be implemented with an electronic circuit or with a mechanical timer plus an electrical switch. The delay time of the delay control device can be flexibly adjusted as needed.

[0043] The second embodiment of the underground electric heating wax cleaning tool proposed by the present invention: On the basis of the first embodiment of the present invention, the delay control device adopts the method of a mechanical timer plus an electrical switch, specifically including a mechanical timer and a micro switch; the mechanical action component of the mechanical timer is connected to the mechanical touch component of the micro switch, and the mechanical action of setting the timing of the mechanical timer starts the timing, and this mechanical action pushes the contacts of the micro switch to disconnect; until the timing expires, the mechanical timer mechanically releases the micro switch, and the contacts of the micro switch are connected. The heating element is connected to a wire with an insulating layer, and the wire passes through the channel of the electric heating head and is connected to a group of contacts of the micro switch, and the group of contacts is further connected to a battery pack. The advantage of the delay control device composed of a mechanical timer and a micro switch is that, in the high-temperature environment underground, the mechanical timer is more stable and reliable than the conventional normal temperature electronic circuit, and has a lower cost than the high-temperature electronic circuit. The disadvantage is that the timing error is large.

[0044] Embodiment 3 of the downhole electric heating wax cleaning tool proposed by the present invention: Based on embodiment 1 of the present invention, the delay control device included in the power supply component is a delay switch composed of electronic devices, and the delay switch is respectively connected to the battery pack and the electric heating body.

[0045] Embodiment 4 of the downhole electric heating wax removal tool proposed by the present invention: Based on embodiment 3 of the present invention, the power supply assembly further includes a temperature control circuit, and a temperature sensor is embedded in the electric heating head or the blade; the temperature sensor is connected to the temperature control circuit. When the temperature sensor is embedded in the blade, the temperature sensor is connected to the temperature control circuit through the hole in the electric heating head. The addition of the temperature control circuit can keep the blade within the most economical wax removal temperature range. The temperature value of the temperature control circuit can be flexibly set according to the wax removal temperature required for each well, thereby maximizing the energy conservation and utilization of the battery pack.

[0046] Embodiment 5 of the underground electric heating wax cleaning tool proposed by the present invention: Figures 1 to 11As shown, the downhole electrothermal wax removal tool comprises, from top to bottom, an upper connector 1, an intermediate tube 2, and an electric heating head 3, each connected in sequence. The electric heating head 3 has an internal cavity, namely, the electric heating head cavity 301. The upper connector 1, intermediate tube 2, and electric heating head 3 are connected to form an externally sealed internal space, and the connection between these three components is sealed using a threaded connection and a double O-ring rubber seal. The internal space houses the power supply assembly, which includes a battery pack and a delay / temperature control circuit 6. The delay / temperature control circuit 6 comprises a delay circuit and a temperature control circuit. The temperature control circuit comprises three independent temperature control circuits, each of which independently detects the temperature of one of the blades 4 and controls the current flowing through the electric heating element within that blade 4 based on the detected temperature, thereby controlling the temperature of the blade 4. Both the delay circuit and the temperature control circuit can be individually set to the desired delay time and control temperature according to the requirements of different downhole operations. The battery pack comprises 16 battery cells 5, which are connected end-to-end in series.

[0047] The outer circumference of the electric heating head 3 is a rotating surface, and the outer diameter is smaller than the inner diameter of the pipe to be cleaned of wax, so it can just be lowered into the pipe to be cleaned of wax. The upper end of the electric heating head 3 is connected to the intermediate tube 2, and the lower part is provided with three blades 4 with the outer circumference of the blade pointing downward and the rotating surface. The three blades 4 are evenly distributed along the circumference of the electric heating head 3 and are separated from each other. The three blades 4 are separated from each other with gaps. The blades 4 can therefore be elastically deformed and bent to adapt to the uneven inner wall of the pipe. A channel 402 is left between the blades 4, away from the blade tip, to allow fluid to pass through, so that the wax fragments cut off by the blades 4 can flow with the well fluid and further flow to the wellhead with the well fluid.

[0048] Each blade 4 is engraved with a surrounding electric heating groove 8a and a linear sensor groove 9a on its outer surface. There is a hole at each end of the electric heating groove 8a and one end of the sensor groove 9a leading to the inner cavity 301 of the electric heating head. These holes are the electric heating wire hole 8b and the temperature sensor wire hole 9b.

[0049] For each blade 4, an electric heater 8 is embedded in the electric heater groove 8a. The electric heater 8 is a stainless steel tube with an outer diameter of 2mm. A heating wire is passed through the center of the tube, and magnesium oxide insulating material is filled between the heating wire and the inner wall of the stainless steel tube. The depth of the electric heater groove 8a is greater than the maximum outer diameter of the electric heater 8, and the electric heater 8 fits tightly against the inner wall of the electric heater groove 8a. The electric heater 8 is only distributed on the cutting edge of the blade, and the other part is a wire with an insulating outer layer, the electric heater connection line 10, which connects the electric heater 8 to the delay / temperature control circuit 6. The outer side of the blade 4 is engraved with the same groove 8a for embedding the electric heater connection line 10. The electric heater 8 is embedded in the blade 4 and directly contacts the blade 4. The heat emitted by the electric heater 8 is all transferred to the blade 4, and the limited energy stored in the battery pack is utilized to the maximum extent.

[0050] Each blade 4 is engraved with a sensor slot 9a, the depth of which is greater than the maximum outer diameter of the sensor 9. The portion connecting the sensor 9 to the time delay / temperature control circuit 6 is a sensor body connection 11. This sensor body connection 11 connects to the circuit board 602 of the time delay / temperature control circuit 6 through the same sensor slot 9a and temperature sensor hole 9b.

[0051] For each blade 4, the heating element 8 is connected to a heating element connection line 10. This connection line 10 passes through the heating element connection hole 8b of the heating head 3 and is connected to the circuit board 602 of the delay / temperature control circuit 6. The circuit board 602 is further connected to the battery pack. After the heating element connection line 10 passes through the heating element connection hole 8b, the hole is sealed to prevent harmful substances from entering the heating head cavity 301 under the high-pressure environment underground and damaging the battery pack or the delay / temperature control circuit 6. The grooves 8a and 9a on the blade 4, where the heating element 8, sensor 9, heating element connection line 10, and sensor connection line 11 are embedded, are filled with high-temperature resistant, high-strength material, covering the heating element 8, sensor 9, heating element connection line 10, and sensor connection line 11 to prevent corrosion and impact damage. Similarly, after passing through the heating element connection line 10 and sensor connection line 11, the heating element connection hole 8b and temperature sensor connection hole 9b of the heating head 3 are filled and sealed with high-temperature resistant, high-strength material. The present invention uses a two-component high-temperature resistant material with high strength and can withstand temperatures up to 200°C.

[0052] The delay / temperature control circuit 6 includes a delay circuit and three independent temperature control circuits. Each temperature control circuit is connected to the electric heating element 8 and temperature sensor 9 of one of the three blades 4, independently detecting and controlling the temperature of its own blade 4 to reach the temperature preset by the temperature control circuit. The circuit element 601 is an electronic component with an operating temperature greater than 85°C. The circuit element 601 is soldered to a circuit board 602, and both ends of the circuit board 602 have multiple solder points for external wiring. The solder points at one end of the circuit board 602 connect to the three sets of electric heating element connection lines 10 and sensor connection lines 11 to the three blades 4; the solder points at the other end connect to the positive busbar 12 of the circuit leading to the battery pack and the negative ground formed by the upper connector 1, the middle tube 2, and the electric heating head 3.

[0053] The battery pack consists of sixteen 3.2V AM cells 5 connected end-to-end in series. To ensure reliable connection between the cells 5, adjacent cells 5 are connected by inter-cell wires 17, each welded to the positive electrode 501 and the negative electrode 502. Insulation pads 16 are also placed between the cells 5 to prevent impact damage to the positive and negative electrodes.

[0054] One end of the battery pack's positive busbar 15 is welded to the positive electrode 501 of the bottommost battery cell 5, and the other end is welded to the end of the positive jack 13. The positive jack 13 plugs into the positive pin 14, the end of which is welded to the circuit's positive busbar 12. This plug-and-play connection facilitates the assembly and connection of the upper connector 1, intermediate tube 2, and electric heating head 3. A battery pack damper 19 is installed between the battery pack and the time delay / temperature control circuit 6. The positive jack 13 is secured to the battery pack damper 19, and the positive pin 14 is plugged into and secured to the upper end of the time delay / temperature control circuit 6.

[0055] The negative pole of the battery pack needs to be grounded, that is, the negative pole of the battery pack is connected to the ground formed by the connection of the upper connector 1, the intermediate cylinder 2, and the electric heating head 3. The negative pole is connected to the delay / temperature control circuit 6 through this ground, and together with the positive busbar, it forms a power supply circuit. In order to ensure that the negative pole is reliably connected to the negative ground formed by the connection of the upper connector 1 and the intermediate cylinder 2 when the upper connector 1 and the intermediate cylinder 2 are installed, the negative pole of the battery pack is grounded with multiple components, such as Figure 6 As shown, it includes a battery pack negative busbar 18, a battery pack shock absorber seat 19, a battery pack negative busbar pin 20, a negative grounding jumper 21, a negative grounding screw 22, a negative grounding jack 23, a grounding jack buffer seat 24, a grounding jack buffer spring 25, and a battery pack shock absorber spring 26. The two ends of the battery pack negative busbar 18 are respectively welded to the negative electrode 502 of the topmost battery cell 5 and the battery pack negative busbar pin 20; the two ends of the negative grounding jumper 21 are respectively welded to the negative grounding screw 22 and the negative grounding jack 23; the battery pack negative busbar pin 20 is plugged into the negative grounding jack 23; and the negative grounding screw 22 is connected to the upper connector 1. The battery pack shock absorber 19 and battery pack shock absorber spring 26 provide elastic support between the battery pack and the upper connector 1, ensuring close contact between each battery cell 5 and the inter-cell insulation pad 16, as well as close contact between the battery pack, the battery pack shock absorber 19, and the delay / temperature control circuit 6, thereby ensuring a secure connection between the positive jack 13 and the positive pin 14. The ground jack buffer seat 24 and the ground jack buffer spring 25 allow the negative ground jack 23 to float up and down with the battery pack negative busbar pin 20, maintaining a secure connection between the negative busbar pin 20 and the negative ground jack 23.

[0056] The blade 4 has an inward chamfer 401 on its tip. This allows the blade 4 to traverse hard protrusions on the pipe's inner wall without getting stuck. However, the radially inward dimension of this chamfer 401 should be limited, as this would hinder the removal of wax deposits close to the pipe's inner wall. Based on multiple experiments, a suitable radially inward dimension of this chamfer 401 is between 0.75 and 1.1 mm.

[0057] In order to improve thermal conductivity, the blade 4 can be made of copper alloy. In this embodiment, in order to ensure thermal conductivity and high mechanical strength at the same time, the entire electric heating head is made of aluminum bronze alloy material by integral cutting.

[0058] The downhole electric wax removal tool in the above embodiment can be deployed underground using a wireline tool to perform wax scraping operations. The wireline tool comprises at least a rope cap and a weighted rod, with the downhole electric wax removal tool connected to the weighted rod. Before deploying the tool, the delay time of a mechanical timer or delay circuit and the predetermined temperature value of the temperature control circuit are set. When the electric wax removal tool reaches the wax accumulation depth underground and the delay time of the delay circuit expires, the electric heater 8 on the blade 4 is connected to the electric current and begins heating. As the blade 4 heats, it cuts the wax accumulation downward. A temperature sensor 9 located on each blade 4 continuously monitors the temperature of the blade 4. When the temperature of the blade 4 reaches the predetermined temperature set by the temperature control circuit, the temperature control circuit reduces or cuts off the current to the electric heater 8 of the blade 4, thereby controlling the temperature of the blade 4. Each of the three blades 4 has an independent temperature control circuit, connected to its own temperature sensor 9 and electric heater 8, to independently control the temperature of each blade. This allows for the heating of each blade 4 in the event of uneven wax accumulation around the pipe wall, thereby saving electricity. The cut wax fragments flow upward with the downhole fluid through the channels 402 between the blades 4 toward the wellhead.

[0059] The sixth embodiment of the underground electric heating wax cleaning tool proposed by the present invention: Figure 12 、 13 As shown, for cable power supply, the apparatus comprises an upper connector, an intermediate barrel, a power supply assembly, and an electric heating head. In this embodiment, the upper connector is a cable upper connector 31, and the intermediate barrel is a cable intermediate barrel 32. The cable upper connector 31, the cable intermediate barrel 32, and the electric heating head 3 are connected to form an externally sealed internal space; the internal space accommodates the power supply assembly. The cable upper connector 31 is connected to downhole tools used for cable logging and well testing, such as cable connectors (bridles), to achieve mechanical connection of the cable to the downhole electric heating wax removal tool and power connection to the electric heating element 3.

[0060] In this embodiment, the structure of the electric heating head is identical to that of the electric heating head 3 in Example 6. It features a rotating outer surface with an inner cavity 301. Its upper end is connected to the upper cable connector 31, and its lower portion features three blades 4, each with its tip facing downward and its outer surface rotating. These three blades are distributed along the circumference of the electric heating head and separated from each other, with channels 402 between them allowing wax removal debris to pass along with the fluid. As in Example 6, the blades are embedded with heating elements 8 for heating the blades 4. The heating element 8 is connected to the power supply assembly by a wire that passes through a channel in the electric heating head 3 and into the inner space; this channel is sealed.

[0061] Different from the sixth embodiment, the power supply assembly shown includes a cable temperature control circuit 36, but does not include a battery pack and a delay circuit. In this embodiment, the cable temperature control circuit 36 ​​also includes three independent temperature control loops, which control the temperatures of the three blades 4 respectively.

[0062] Because the power supply relies on a cable, the upper connector in this embodiment is a cable connector 31 designed specifically for cable power. Because there is no battery pack, the intermediate barrel is a shorter cable intermediate barrel 32. The threads at both ends of the cable intermediate barrel 32 are threaded in opposite directions, one end turning left and the other right. This prevents the internal connecting wires from becoming tangled during assembly.

[0063] The cable connector 31 has a central through-hole, with a cable connector mounted above it. The cable connector comprises a cable connector 35 and an insulating cable connector 37. The upper end of the cable connector 35 receives the pins corresponding to the core wires of the downhole test cable, while the lower end is connected to a cable temperature control circuit 36 ​​via the cable core wire 33. The cable temperature control circuit 36 ​​is connected to the cable ground wire 34, the heating element connection wire 10, and the sensor connection wire 11.

[0064] Based on Example 6, the intermediate cable barrel 32 can be omitted, and the upper cable connector can be directly connected to the electric heating head, with an O-ring installed at the connection. This eliminates one connection, reduces the risk of seal leakage, and reduces costs, but it is more difficult to avoid kinking the cables during installation. This connection method requires sufficient internal cavities in both the upper cable connector and the electric heating head to accommodate the power supply group.

[0065] For the cable-powered downhole electric wax removal tool described above, the power supply assembly can include a splitter, rather than a temperature control circuit, that connects the cable connector and the heating element. This allows the cable core to power the heating element. While this solution lacks temperature regulation, saving power is not essential for cable-powered systems. The blade temperature can be controlled by determining the appropriate supply current through testing. This current can be controlled from the surface via the cable to the blade of the electric wax removal tool. This solution saves the cost of high-temperature temperature control circuitry.

[0066] The technical solution proposed by the present invention combines the methods of mechanical wax cleaning and electric wax cleaning. Steel wire or cable downhole operation equipment can be lowered into the downhole pipeline, and the blades of the mechanical wax cleaning are directly heated by electric heat. The wax is dissolved by heat during mechanical cutting, which overcomes the problem that pure mechanical wax cleaning is difficult to remove when the wax is thick and causes the wax scraper to get stuck easily, and there is no chemical pollution. The battery pack is used to heat the slices, and the electric heat energy is utilized to the maximum extent, saving electricity. Multiple blades increase the length of contact between the cutting edge and the wax during cutting, which speeds up the cutting speed. Because the blades are separated from each other and there is a gap between them, the blades can bend elastically to adapt to the uneven inner wall of the pipeline. Furthermore, a channel is left between the blades, away from the tip of the blade, to allow wax cleaning fragments to pass through with the fluid, so that the wax fragments cut by the blades can flow through with the well fluid, and the wax cleaning fragments can be discharged to the wellhead with the well fluid.

Claims

1. A downhole electrothermal wax removal tool, comprising an upper joint, a power supply assembly, and an electric heating head, or further comprising an intermediate tube, wherein the upper joint is connected to the electric heating head, or the upper joint, the intermediate tube, and the electric heating head are sequentially connected to form an externally sealed internal space; the internal space accommodates the power supply assembly; and characterized in that: The outer periphery of the electric heating head is a rotating surface with an inner cavity, the upper end of which is connected to an upper joint or an intermediate cylinder, and the lower part is provided with at least two blades with downward-pointing blade tips and an outer periphery of the rotating surface; the at least two blades are distributed along the circumference of the electric heating head and are separated from each other, and a channel is left between the blades to allow wax cleaning debris to pass through with the fluid; The blade is embedded with an electric heating element for heating the blade; The electric heating element is connected to a wire, and the wire passes through a hole provided in the electric heating head and enters the internal space to be connected to the power supply component; the hole is sealed.

2. The downhole electric heating wax removal tool according to claim 1, characterized in that: The power supply assembly includes a battery pack or a delay control device at the same time; the delay control device is connected between the electric heating body and the battery pack; the battery pack includes at least three battery cells, which are connected end to end in series.

3. The downhole electric heating wax removal tool according to claim 2, characterized in that: The delay control device comprises a mechanical timer and a micro switch, and two ends of a group of contacts of the micro switch are respectively connected to the electric heating body and the battery pack.

4. The downhole electric heating wax removal tool according to claim 2, characterized in that: The delay control device includes a delay switch composed of electronic components, and the delay switch is connected to the battery pack and the electric heating body respectively.

5. The downhole electric heating wax removal tool according to any one of claims 1 to 4, characterized in that: The power supply component includes a temperature control circuit. A temperature sensor is embedded in the electric heating head or the blade. A wire with an insulating jacket passes through the hole of the electric heating head to connect the temperature sensor embedded in the blade to the temperature control circuit.

6. The downhole electric heating wax removal tool according to claim 5, characterized in that: Each blade is embedded with an electric heater and a temperature sensor; the temperature control circuit includes multiple independent temperature control loops; each loop is connected to a temperature sensor and electric heater located on a different blade, independently detecting the temperature of the blade to which it is connected, and controlling the current of the electric heater in the blade according to the temperature.

7. The downhole electric thermal wax removal tool according to any one of claims 1, 2, 3, 4, and 6, characterized in that: The outer side of the blade tip is provided with an inward chamfer.

8. The downhole electric heating wax removal tool according to claim 1, characterized in that: The upper connector is a cable upper connector with a central through hole, and a cable connector is installed at the upper end of the central through hole; the power supply component includes a temperature control circuit, and the blade is provided with a temperature sensor. The wire with an insulating jacket passes through the hole of the electric heating head to connect the temperature sensor to the temperature control circuit.

9. The downhole electric heating wax removal tool according to claim 8, characterized in that: The power supply component includes a splitter but does not include a temperature control circuit, and the blade does not have a temperature sensor; the splitter is connected to the cable connector and the electric heating element respectively.

10. The downhole electric thermal wax removal tool according to any one of claims 1, 2, 3, 4, 6, 8, and 9, characterized in that: The electric heating head or the blade is made of copper alloy.

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