Deep well thickened oil electric heating viscosity reduction oil extraction device and method

Abstract

The present application relates to a kind of thick oil exploitation technical field, in particular to a kind of deep well thick oil electric heating viscosity reduction oil extraction device and method.The technical scheme is: the lower part of high-temperature cable packer is connected with screw hole screen pipe, the lower end of screw hole screen pipe is connected with cable penetrator, the lower end of cable penetrator is connected with downhole electric heater by cable heat insulation connecting pipe, and the downhole electric heater is located in the lower part of casing;Power cable is lowered into downhole along the annulus between oil pipe and casing from ground, and passes through cable penetrator to cable heat insulation connecting pipe.The beneficial effect is: by using power cable and cable heat insulation connecting pipe with internal ceramic connecting cylinder to connect in relay, power cable is in the upper part of oil well, and the lower part uses cable heat insulation connecting pipe, and multiple ceramic connecting cylinders are combined and connected to replace the role of cable in deep well section, with the functions of high temperature resistance, high pressure resistance and corrosion resistance, so that the electric heating viscosity reduction function of deep well thick oil is realized.

Description

Technical Field

[0001] This invention relates to the field of heavy oil extraction technology, and particularly to a device and method for deep-well heavy oil electric heating viscosity reduction oil extraction. Background Technology

[0002] Heavy oil plays a crucial role in oil extraction. However, its high viscosity and poor fluidity present significant challenges, leading to difficulties in extraction and low economic returns. Currently, the traditional method for heavy oil extraction is thermal recovery, which involves heating the oil reservoir to reduce its viscosity, thereby improving its fluidity and enabling economically efficient extraction. This method is suitable for heavy oil resources with high viscosity that are difficult to develop using conventional waterflooding, and it dominates the development of both ordinary and extra-heavy oils.

[0003] Existing thermal oil recovery methods mainly include steam injection and reservoir combustion. Steam injection utilizes thermal diffusion to reduce the viscosity of heavy oil and increase its fluidity. This process is repeated after a period of extraction: steam injection, well shut-in, removal of the injection tubing, and pumping out the oil. This method suffers from several problems: low efficiency, high energy consumption, significant heat loss, poor economic returns, long extraction cycles, susceptibility to steam channeling, and a higher risk of workplace injuries such as burns. Reservoir combustion involves injecting air or oxygen into the reservoir to ignite some of the crude oil. The high temperature generated by combustion heats unburned areas, achieving both viscosity reduction and oil displacement. However, this method is technically challenging, requires strict control, and carries significant safety risks.

[0004] Another method is electric heating, which involves installing an electric heater downhole in the heavy oil reservoir and transmitting electricity to the well via cable to heat the heavy oil. Simultaneously, during oil extraction, the cable's self-heating can provide auxiliary heating to the crude oil. However, this method has drawbacks: the cable's durability must be considered, especially in deep heavy oil reservoirs. Due to the high-temperature and high-pressure environment downhole, such as at depths above 3000 meters, the cable is constantly exposed to high temperature, high pressure, and corrosive liquids. Therefore, strict technical requirements are placed on the cable, particularly high temperature resistance: generally, the cable must withstand temperatures of 145-250℃, for example, using cables with polyimide / F46 composite film and EPDM rubber combined insulation. This results in high cable manufacturing costs and makes it difficult to meet the requirements for viscosity reduction in deeper, higher-temperature heavy oil wells.

[0005] A search revealed Chinese patent number ZL200620089878.8, entitled "A Medium-Frequency Electric Heating Oil Production Device for Heavy Oil," which comprises a pumping unit, a hollow rod suspension rope device, a wellhead device, a medium-frequency power supply device, a wellhead surface cable, a hollow rod, an armored electric heater, a screen pipe, and a plug. In this device, the pumping unit is connected to the hollow rod suspension rope device via a rope braid, which suspends the hollow sucker rod to form the pumping system. The armored electric heater is installed inside the hollow sucker rod and fixed at the upper end of the hollow rod suspension rope device with an anti-detachment and anti-wear device before being crimped to the wellhead surface cable sleeve. The medium-frequency power supply device is connected to the wellhead surface cable to form the electric heating system. The plug and screen pipe, the screen pipe and pump inlet, and the pump pipe and wellhead device are threadedly connected to form the oil flow channel. The problem is that it does not take into account the high temperature and high pressure environment in deep wells. For example, when the cable is at a depth of more than 3,000 meters, it is in a high temperature, high pressure and corrosive liquid environment for a long time. Therefore, there are strict technical requirements for the cable, especially the high temperature resistance: the cable is generally required to withstand temperatures of 145-250℃. Although the above patent is placed under the hollow sucker rod and inserted into the well, it is still necessary to consider the high temperature resistance. Otherwise, the radiation temperature of the electric heater and the high temperature in the deep well will cause the cable to fail to meet the requirements. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned deficiencies in existing technologies by providing a deep-well heavy oil electric heating viscosity reduction device and method. This method utilizes a power transmission cable connected to an internally installed ceramic connecting tube with a cable insulation connection pipe. The power transmission cable is located in the upper middle section of the oil well, while the lower section uses a cable insulation connection pipe. Multiple sets of ceramic connecting tubes are combined and connected to wrap a conductive rod, thus replacing the cable in the deep well section. This method offers high temperature resistance, high pressure resistance, and corrosion resistance, thereby achieving the electric heating viscosity reduction function for deep-well heavy oil, reducing heavy oil extraction costs, and improving extraction safety.

[0007] This invention discloses a deep-well heavy oil electric heating viscosity-reducing oil production device. The technical solution includes a sucker rod, a sucker pump, a power transmission cable, and a high-temperature cable packer. It further includes a screw-hole screen, a cable pass-through device, a cable insulation connection pipe, a downhole electric heater, a lower inner plug, and an upper inner plug. The lower part of the high-temperature cable packer is connected to the screw-hole screen. The lower end of the screw-hole screen is connected to the cable pass-through device via the upper inner plug. The lower end of the cable pass-through device is connected to the downhole electric heater via the cable insulation connection pipe. The downhole electric heater is located at the lower part of the casing. The power transmission cable originates from the ground... The cable is lowered into the well along the annulus between the tubing and casing, passing through a cable passer to the upper insulating coupling of the cable insulation connection pipe. The live wire is connected to the conductive rod through the lower inner plug, and the neutral wire is in contact with the inner wall of the cable passer. The conductive rod is wrapped by multiple sets of ceramic connecting sleeves. The lower end of the cable insulation connection pipe is connected to the upper live wire terminal of the downhole electric heater through a live wire butt male connector. The live wire runs along the cable insulation connection pipe to the downhole electric heater, thereby heating and reducing the viscosity of the downhole heavy oil. The reduced viscosity oil enters the screw hole screen pipe and is then pumped to the surface.

[0008] Preferably, the downhole electric heater includes a live wire connector, a heating resistance wire, a neutral wire conductive tube, a ceramic sand tube, a bottom insulating cap, a bottom insulating sleeve, and an insulating pad. The heating resistance wire is installed inside the neutral wire conductive tube, and the ceramic sand tube is fitted around the outside of the neutral wire conductive tube. The bottom insulating sleeve is connected to the lower end of the ceramic sand tube through the bottom insulating cap, and an insulating pad is installed inside the bottom insulating sleeve. The upper end of the heating resistance wire is connected to the live wire connector, and the lower end of the heating resistance wire is connected to the bottom inner wall of the neutral wire conductive tube.

[0009] Preferably, the above-mentioned cable insulation connection pipe includes a straight connecting pipe, an electrode connector, a live wire connector, an insulating ring, an upper insulating clamp, a conductive rod, a ceramic connecting cylinder, a live wire connector, and a lower insulating clamp. The lower end of the straight connecting pipe is connected to the electrode connector, and the live wire connector is installed inside the electrode connector. An insulating ring is installed between the live wire connector and the electrode connector. The upper insulating clamp, the ceramic connecting cylinder, and the lower insulating clamp are installed inside the straight connecting pipe, and a conductive rod is installed at the center of the upper insulating clamp, the ceramic connecting cylinder, and the lower insulating clamp. The lower end of the conductive rod is connected to the live wire connector.

[0010] Preferably, an insulating pad is installed at the lower end of the straight connecting pipe, and the upper insulating pad contacts the upper end of the insulating ring. A lower insulating pad is installed at the lower end of the insulating ring, and the lower insulating pad contacts the lower end of the inner wall of the electrode connector.

[0011] Preferably, the ceramic connecting cylinder adopts a circular ring structure made of ceramic, and the inner diameter of the ceramic connecting cylinder is larger than the outer diameter of the conductive rod, wherein the conductive rod is a cylindrical structure.

[0012] Preferably, the upper insulating coupling and the lower insulating coupling are cylindrical structures, and the inner diameter of the upper insulating coupling and the lower insulating coupling is larger than the outer diameter of the conductive rod.

[0013] Preferably, the upper part of the above-mentioned live wire mating male connector is a cylindrical structure, and the lower part is a frustum conical structure. The frustum conical structure of the lower part of the live wire mating male connector extends to the lower end of the lower insulating coupling and is movably connected to the inside of the live wire mating joint through a locking ring.

[0014] Preferably, the cable passer includes a cable passer tube, a cable passer outer protrusion, and a cable pass through hole. The cable passer tube has a cable passer outer protrusion on its middle outer wall, and a cable pass through hole is provided inside the cable passer outer protrusion. One end of the cable pass through hole is connected to the inner cavity of the cable passer tube, and the other end is connected to the outer wall of the cable passer tube along the cable passer outer protrusion.

[0015] Preferably, the upper end of the live wire connector is cylindrical, the lower end is located in the inner cavity of the neutral wire conductive tube, and the outer diameter of the live wire connector is smaller than the inner diameter of the neutral wire conductive tube. The upper end of the live wire connector extends out of the neutral wire conductive tube and passes through the lower insulating pad of the upper cable insulation connection tube to be inserted into the inner cavity of the live wire mating joint.

[0016] The method of using the deep-well heavy oil electric heating viscosity-reducing oil production device mentioned in this invention includes the following process:

[0017] 1. The oil pipe is connected to the screw screen, cable passer, cable insulation connection pipe and downhole electric heater and then lowered into the casing. At the same time, the power cable is lowered from the ground along the annulus between the oil pipe and the casing for a distance downhole, and then passes through the cable passer. The live wire and neutral wire are separated in the inner cavity of the cable passer. The live wire is connected to the conductive rod through the lower inner plug and the upper insulating coupling. The neutral wire is connected to the inner wall of the cable passer. The conductive rod is wrapped by multiple sets of ceramic connecting cylinders to realize the power relay connection in the deep well. The live wire is connected to the downhole electric heater in the deep well through the cable insulation connection pipe. The current loop is connected to the neutral wire of the power cable through the neutral wire conductive pipe, the electrode joint, the straight connection pipe and the inner wall of the cable passer. The lower end of the downhole electric heater is close to the bottom of the artificial well.

[0018] 2. Start the power supply on the ground and connect the power to the cable passer in the well through the power transmission cable. The live wire is connected to the conductive rod in the insulated connection pipe of the cable. The conductive rod is wrapped with multiple sets of ceramic connecting cylinders to realize the power relay in the deep well. The cable insulated connection pipe is used to withstand the high temperature, high pressure and corrosion of the deep well section. The heavy oil in the deep well is heated by the downhole electric heater to increase the temperature and reduce the viscosity, which improves the fluidity of the oil. The oil enters the screw screen pipe and drives the oil pump through the sucker rod to extract the oil to the surface.

[0019] 3. If the viscosity of the heavy oil is reduced by heating, but its fluidity is still insufficient for the oil pump to extract it, the oil pump is raised again, and thin oil is injected into the well through the tubing at the wellhead on the surface. The thin oil enters the casing through the screw screen. The viscosity of the heavy oil is reduced by the combination of the thin oil and the heating of the downhole electric heater, so that the fluidity of the oil meets the requirements for extraction by the oil pump. The oil is then extracted to the surface by the oil pump.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention utilizes a downhole electric heater to directly heat heavy oil in deep wells, thereby improving thermal energy utilization efficiency and enhancing the fluidity of the heavy oil to meet the requirements for pumping to the surface. Simultaneously, the power cable within the wellbore provides heating, preventing the oil from losing fluidity due to decreased ground temperature. Furthermore, thin oil can be injected to assist in oil production as needed. Additionally, the invention's insulated cable connection pipe overcomes the damage to cables caused by the high temperatures of deep wells. Multiple sets of ceramic connecting cylinders encasing conductive rods achieve electrical relay connection in the deep well, allowing the live wire to travel along the insulated cable connection pipe to the downhole electric heater in the deep well, creating a current loop. The invention connects sequentially to the neutral wire of the power transmission cable via a neutral conductor, electrode connector, and straight connecting pipe, all connected to the inner wall of the cable pass-through device. By using a cable insulation connection pipe to relay the connection to the downhole electric heater, it replaces the existing cable, avoiding the inability of the existing cable protective layer to meet the high temperature, high pressure, and corrosive requirements of deep well sections. This allows for the smooth implementation of deep well electric heating-assisted oil production. Furthermore, the cable pass-through device enables a smooth transition between the cable insulation connection pipe and the power transmission cable. In summary, this invention meets the requirements of the high temperature, high pressure, and corrosive environment of deep heavy oil reservoirs, reduces the cost of heavy oil extraction, and improves the safety of the heavy oil production process. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall construction process of the present invention;

[0023] Figure 2 This is a schematic diagram of the structure of an underground electric heater;

[0024] Figure 3 This is a schematic diagram of the structure of the cable insulation connection pipe;

[0025] Figure 4 This is a schematic diagram of the internal filling structure of the cable insulation connection pipe;

[0026] Figure 5 This is a schematic diagram of the cable crossing device;

[0027] Figure 6This is a schematic diagram of the construction process when adding thin oil according to the present invention;

[0028] In the diagram: 1. Sucker rod; 2. Oil pump; 3. High-temperature cable packer; 4. Screw hole screen; 5. Power transmission cable; 6. Cable passer; 7. Cable insulation connection pipe; 8. Downhole electric heater; 9. Casing; 10. Tubing; 11. Lower inner plug; 12. Heavy oil reservoir; 13. Artificial bottom hole; 14. Upper inner plug; 15. Annular cable plug.

[0029] 6.1 Cable passer tube body, 6.2 Cable passer external protrusion, 6.3 Cable pass through hole, 7.1 Straight connection tube, 7.2 Electrode connector, 7.3 Live wire butt connector, 7.4 Lower insulating pad, 7.5 Insulating ring, 7.6 Locking ring, 7.7 Upper insulating pad, 7.8 Upper insulating clamp, 7.9 Conductive rod, 7.10 Ceramic connecting cylinder, 7.11 Live wire butt male connector, 7.12 Lower insulating clamp, 8.1 Live wire terminal, 8.2 Heating resistance wire, 8.3 Neutral wire conductive tube, 8.4 Ceramic sand tube, 8.5 Bottom insulating cap, 8.6 Bottom insulating sleeve, 8.7 Insulating pad. Detailed Implementation

[0030] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0031] Example 1, referring to Figures 1-6 This invention discloses a deep-well heavy oil electric heating viscosity-reducing oil production device, comprising a sucker rod 1, a sucker pump 2, a power transmission cable 5, and a high-temperature cable packer 3. It also includes a screw-hole screen 4, a cable passer 6, a cable insulation connection pipe 7, a downhole electric heater 8, a lower inner plug 11, and an upper inner plug 14. The lower part of the high-temperature cable packer 3 is connected to the screw-hole screen 4, utilizing the high-temperature cable packer 3 for reservoir insulation, thus improving thermal energy utilization efficiency. The lower end of the screw-hole screen 4 is connected to the cable passer 6 via the upper inner plug 14, and the lower end of the cable passer 6 is connected to the downhole electric heater 8 via the cable insulation connection pipe 7. The downhole electric heater 8 is located at the lower part of the casing 9. The power transmission cable 5 is lowered into the well from the ground along the annulus between the tubing 10 and the casing 9. It passes through the cable passer 6 and enters the upper insulating coupling 7.8 of the cable insulation connection pipe 7. The live wire is connected to the conductive rod 7.9 through the lower inner plug 11, and the neutral wire is in contact with the inner wall of the cable passer 6. The conductive rod 7.9 is wrapped by multiple sets of ceramic connecting cylinders 7.10. The lower end of the cable insulation connection pipe 7 is connected to the upper live wire connector 8.1 of the downhole electric heater 8 through the live wire butt male connector 7.11. The live wire is connected to the downhole electric heater 8 along the cable insulation connection pipe 7, so as to heat and reduce the viscosity of the downhole heavy oil. The reduced viscosity oil enters the screw screen pipe 4 and is extracted to the surface by the oil pump 2.

[0032] Reference Figure 2 The downhole electric heater 8 mentioned in this invention includes a live wire connector 8.1, a heating resistance wire 8.2, a neutral wire conductive tube 8.3, a ceramic sand tube 8.4, a bottom insulating cap 8.5, a bottom insulating sleeve 8.6, and an insulating pad 8.7. The heating resistance wire 8.2 is installed inside the neutral wire conductive tube 8.3, and the ceramic sand tube 8.4 is fitted outside the neutral wire conductive tube 8.3 for heat dissipation and insulation. The bottom insulating sleeve 8.6 is connected to the lower end of the ceramic sand tube 8.4 through the bottom insulating cap 8.5, and an insulating pad 8.7 is installed inside the bottom insulating sleeve 8.7. The upper end of the heating resistance wire 8.2 is connected to the live wire connector 8.1, and the lower end of the heating resistance wire 8.2 is connected to the bottom inner wall of the neutral wire conductive tube 8.3.

[0033] Reference Figures 3-4 The cable insulation connection pipe 7 mentioned in this invention includes a straight connection pipe 7.1, an electrode connector 7.2, a live wire connector 7.3, an insulating ring 7.5, an upper insulating clamp 7.8, a conductive rod 7.9, a ceramic connecting cylinder 7.10, a live wire male connector 7.11, and a lower insulating clamp 7.12. The lower end of the straight connection pipe 7.1 is connected to the electrode connector 7.2. The live wire connector 7.3 is installed inside the electrode connector 7.2. An insulating ring 7.5 is installed between the live wire connector 7.3 and the electrode connector 7.2. The upper insulating clamp 7.8, the ceramic connecting cylinder 7.10, and the lower insulating clamp 7.12 are installed inside the straight connection pipe 7.1. A conductive rod 7.9 is installed at the center of the upper insulating clamp 7.8, the ceramic connecting cylinder 7.10, and the lower insulating clamp 7.12. The lower end of the conductive rod 7.9 is connected to the live wire male connector 7.11.

[0034] An insulating pad 7.7 is installed at the lower end of the straight connecting pipe 7.1, and the upper insulating pad 7.7 contacts the upper end of the insulating ring 7.5. A lower insulating pad 7.4 is installed at the lower end of the insulating ring 7.5, and the lower insulating pad 7.4 contacts the lower end of the inner wall of the electrode connector 7.2.

[0035] The ceramic connecting cylinder 7.10 is made of ceramic and has a ring-shaped structure. The inner diameter of the ceramic connecting cylinder 7.10 is larger than the outer diameter of the conductive rod 7.9, which has a cylindrical structure.

[0036] The aforementioned upper insulating coupling 7.8 and lower insulating coupling 7.12 are cylindrical structures, and the inner diameter of the upper insulating coupling 7.8 and lower insulating coupling 7.12 is larger than the outer diameter of the conductive rod 7.9.

[0037] The upper part of the above-mentioned live wire male connector 7.11 is a cylindrical structure, and the lower part is a frustum conical structure. The frustum conical structure of the lower part of the live wire male connector 7.11 extends to the lower end of the lower insulating coupling 7.12 and is movably connected to the inside of the live wire male connector 7.3 through the locking ring 7.6.

[0038] Reference Figure 5 The cable passer 6 mentioned in this invention includes a cable passer tube 6.1, a cable passer outer protrusion 6.2, and a cable pass-through hole 6.3. The cable passer tube 6.1 has a cable passer outer protrusion 6.2 on its middle outer wall, and a cable pass-through hole 6.3 is provided inside the cable passer outer protrusion 6.2. One end of the cable pass-through hole 6.3 is connected to the inner cavity of the cable passer tube 6.1, and the other end is connected to the outer wall of the cable passer tube 6.1 along the cable passer outer protrusion 6.2.

[0039] The upper end of the live wire connector 8.1 is cylindrical, and the lower end is located inside the cavity of the neutral wire conductive tube 8.3. The outer diameter of the live wire connector 8.1 is smaller than the inner diameter of the neutral wire conductive tube 8.3. The upper end of the live wire connector 8.1 extends outside the neutral wire conductive tube 8.3 and passes through the lower insulating pad 7.4 of the upper cable insulation connecting tube 7 and is inserted into the cavity of the live wire mating connector 7.3.

[0040] The method of using the deep-well heavy oil electric heating viscosity-reducing oil production device mentioned in this invention includes the following process:

[0041] 1. The oil pipe 10 is connected to the screw screen pipe 4, cable passer 6, cable insulation connection pipe 7, and downhole electric heater 8, and then lowered into the casing 9. Simultaneously, the power cable 5 is lowered from the surface along the annulus between the oil pipe 10 and the casing 9 for a distance downhole, then passes through the cable passer 6. Inside the cable passer 6, the live wire and neutral wire are separated. The live wire is connected to the conductive rod 7.9 via the lower inner plug 11 and the upper insulating coupling 7.8. The neutral wire contacts the inner wall of the cable passer 6 and is then connected via… Multiple sets of ceramic connecting cylinders 7.10 wrap conductive rods 7.9 to achieve power relay connection in deep wells, so that the live wire is connected to the downhole electric heater 8 in deep wells along the cable insulation connecting pipe 7. The current circuit is connected to the neutral wire of the power transmission cable 5 through the neutral wire conductive pipe 8.3, electrode connector 7.2, straight connecting pipe 7.1 and the inner wall of the cable passer 6 in sequence. The downhole electric heater 8 is installed near the heavy oil reservoir 12, and the lower end of the downhole electric heater 8 is close to the artificial well bottom 13.

[0042] 2. Start the power supply on the ground and connect the power to the cable passer 6 downhole through the power transmission cable 5. The live wire is connected to the conductive rod 7.9 inside the cable insulation connection pipe 7. The conductive rod 7.9 is wrapped with multiple sets of ceramic connecting cylinders 7.10 to realize the power relay in the deep well. The cable insulation connection pipe 7 is used to withstand the high temperature, high pressure and corrosion of the deep well section, so that the heavy oil in the deep well is heated by the downhole electric heater 8 to increase the temperature and reduce the viscosity, which improves the fluidity of the oil. The oil enters the screw hole screen pipe 4 and drives the oil pump 2 through the sucker rod 1 to extract the oil to the surface.

[0043] 3. If, after heating and reducing the viscosity of the heavy oil, its fluidity is still insufficient for pumping by pump 2, then pump 2 should be raised again, referring to... Figure 6 At the wellhead on the surface, thin oil is injected into the well through the tubing 10. The thin oil enters the casing 9 through the screw screen 4. The viscosity of the heavy oil is reduced by the combination of the thin oil and the heating of the downhole electric heater 8, so that the fluidity of the oil meets the requirements for being extracted by the oil pump 2. The oil is then extracted to the surface by the oil pump 2.

[0044] Example 2: A deep-well heavy oil electric heating viscosity-reducing oil production device mentioned in this invention includes a sucker rod 1, a sucker pump 2, a power transmission cable 5, and a high-temperature cable packer 3. It also includes a screw-hole screen 4, a cable passer 6, a cable insulation connection pipe 7, a downhole electric heater 8, a lower inner plug 11, and an upper inner plug 14. The lower part of the high-temperature cable packer 3 is connected to the screw-hole screen 4, and the high-temperature cable packer is used for reservoir insulation, improving the efficiency of thermal energy utilization. The lower end of the screw-hole screen 4 is connected to the cable passer 6 through the upper inner plug 14, and the lower end of the cable passer 6 is connected to the downhole electric heater 8 through the cable insulation connection pipe 7. The downhole electric heater 8 is located at the lower part of the casing 9. The power transmission cable 5 is lowered into the well from the ground along the annulus between the tubing 10 and the casing 9. It passes through the cable passer 6 and enters the upper insulating coupling 7.8 of the cable insulation connection pipe 7. The live wire is connected to the conductive rod 7.9 through the lower inner plug 11, and the neutral wire is in contact with the inner wall of the cable passer 6. The conductive rod 7.9 is wrapped by multiple sets of ceramic connecting cylinders 7.10. The lower end of the cable insulation connection pipe 7 is connected to the upper live wire connector 8.1 of the downhole electric heater 8 through the live wire butt male connector 7.11. The live wire is connected to the downhole electric heater 8 along the cable insulation connection pipe 7, so as to heat and reduce the viscosity of the downhole heavy oil. The reduced viscosity oil enters the screw screen pipe 4 and is extracted to the surface by the oil pump 2.

[0045] The difference from Example 1 is:

[0046] An annular cable plug 15 is installed at the outer end of the cable passage through hole 6.3 of the cable passer 6. When the power transmission cable 5 enters the inner cavity of the cable passer 6 along the cable passage through hole 6.3, the annular cable plug 15 can play a sealing role.

[0047] Furthermore, the method of using the deep-well heavy oil electric heating viscosity-reducing oil production device mentioned in this invention includes the following process:

[0048] 1. The oil pipe 10 is connected to the screw screen pipe 4, cable passer 6, cable insulation connection pipe 7 and downhole electric heater 8 and then lowered into the casing 9. At the same time, the power transmission cable 5 is lowered from the ground along the annulus between the oil pipe 10 and the casing 9 for a certain distance downhole, and then passes through the cable passer 6. The live wire and neutral wire are separated in the inner cavity of the cable passer 6. The live wire is connected to the conductive rod 7.9 through the lower inner plug 11 and the upper insulating coupling 7.8. The neutral wire is connected to the inner wall of the cable passer 6. The conductive rod 7.9 is wrapped by multiple sets of ceramic connecting cylinders 7.10 to realize the power relay connection of the deep well. The live wire is connected to the downhole electric heater 8 in the deep well along the cable insulation connection pipe 7. The current loop is connected to the neutral wire of the power transmission cable 5 through the neutral wire conductive pipe 8.3, the electrode connector 7.2, the straight connection pipe 7.1 and the inner wall of the cable passer 6. The lower end of the downhole electric heater 8 is close to the artificial bottom 13.

[0049] 2. Start the power supply on the ground and connect the power to the cable passer 6 downhole through the power transmission cable 5. The live wire is connected to the conductive rod 7.9 inside the cable insulation connection pipe 7. The conductive rod 7.9 is wrapped with multiple sets of ceramic connecting cylinders 7.10 to realize the power relay in the deep well. The cable insulation connection pipe 7 is used to withstand the high temperature, high pressure and corrosion of the deep well section, so that the heavy oil in the deep well is heated by the downhole electric heater 8 to increase the temperature and reduce the viscosity, which improves the fluidity of the oil. The oil enters the screw screen pipe 4 and drives the oil pump 2 through the sucker rod 1 to extract the oil to the surface.

[0050] The above description is merely a partial preferred embodiment of the present invention. Any person skilled in the art can modify the above-described technical solutions or modify them into equivalent technical solutions. Therefore, any simple modifications or equivalent transformations made based on the technical solutions of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A deep-well heavy oil electric heating viscosity-reducing oil production device, comprising a sucker rod (1), a pump (2), a power transmission cable (5), and a high-temperature cable packer (3), characterized in that: It also includes a screw-hole screen (4), a cable passer (6), a cable insulation connection pipe (7), a downhole electric heater (8), a lower inner plug (11), and an upper inner plug (14). The lower part of the high-temperature cable packer (3) is connected to the screw-hole screen (4). The lower end of the screw-hole screen (4) is connected to the cable passer (6) through the upper inner plug (14). The lower end of the cable passer (6) is connected to the downhole electric heater (8) through the cable insulation connection pipe (7). The downhole electric heater (8) is located at the lower part of the casing (9). The power transmission cable (5) is lowered from the ground along the annulus between the tubing (10) and the casing (9) and passes through the cable passer (6). The upper insulating coupling (7.8) of the cable insulation connection pipe (7) is connected to the conductive rod (7.9) through the lower inner plug (11). The neutral wire is connected to the inner wall of the cable passer (6) and the conductive rod (7.9) is wrapped by multiple sets of ceramic connecting cylinders (7.10). The lower end of the cable insulation connection pipe (7) is connected to the upper end of the live wire connector (8.1) of the downhole electric heater (8) through the live wire butt male connector (7.11). The live wire is connected to the downhole electric heater (8) along the cable insulation connection pipe (7) to achieve heating and viscosity reduction of the downhole heavy oil. The viscous oil enters the screw hole screen pipe (4) and is extracted to the surface by the oil pump (2).

2. The deep-well heavy oil electric heating viscosity-reducing oil production device according to claim 1, characterized in that: The downhole electric heater (8) includes a live wire connector (8.1), a heating resistance wire (8.2), a neutral wire conductive tube (8.3), a ceramic sand tube (8.4), a bottom insulating cap (8.5), a bottom insulating sleeve (8.6), and an insulating pad (8.7). The heating resistance wire (8.2) is installed inside the neutral wire conductive tube (8.3), and the ceramic sand tube (8.4) is fitted on the outside of the neutral wire conductive tube (8.3). The bottom insulating sleeve (8.6) is connected to the bottom of the ceramic sand tube (8.4) through the bottom insulating cap (8.5). An insulating pad (8.7) is installed inside the bottom insulating sleeve (8.6). The upper end of the heating resistance wire (8.2) is connected to the live wire connector (8.1), and the lower end of the heating resistance wire (8.2) is connected to the bottom inner wall of the neutral wire conductive tube (8.3).

3. The deep-well heavy oil electric heating viscosity-reducing oil production device according to claim 2, characterized in that: The cable insulation connection pipe (7) includes a straight connection pipe (7.1), an electrode connector (7.2), a live wire connector (7.3), an insulating ring (7.5), an upper insulating clamp (7.8), a conductive rod (7.9), a ceramic connecting cylinder (7.10), a live wire male connector (7.11), and a lower insulating clamp (7.12). The lower end of the straight connection pipe (7.1) is connected to the electrode connector (7.2), and the live wire connector (7.3) is installed inside the electrode connector (7.2). An insulating ring (7.5) is installed between the live wire connector (7.3) and the electrode connector (7.2); an upper insulating clamp (7.8), a ceramic connecting cylinder (7.10), and a lower insulating clamp (7.12) are installed in the inner cavity of the straight connecting pipe (7.1), and a conductive rod (7.9) is installed at the center of the upper insulating clamp (7.8), the ceramic connecting cylinder (7.10), and the lower insulating clamp (7.12), with the lower end of the conductive rod (7.9) connected to the live wire connector (7.11).

4. The deep-well heavy oil electric heating viscosity reduction oil production device according to claim 3, characterized in that: in An upper insulating pad (7.7) is installed at the lower end of the straight connecting pipe (7.1), and the upper insulating pad (7.7) contacts the upper end of the insulating ring (7.5). A lower insulating pad (7.4) is installed at the lower end of the insulating ring (7.5), and the lower insulating pad (7.4) contacts the lower end of the inner wall of the electrode connector (7.2).

5. The deep-well heavy oil electric heating viscosity-reducing oil production device according to claim 4, characterized in that: The ceramic connecting cylinder (7.10) adopts a circular structure made of ceramic, and the inner diameter of the ceramic connecting cylinder (7.10) is larger than the outer diameter of the conductive rod (7.9), which is a cylindrical structure.

6. The deep-well heavy oil electric heating viscosity-reducing oil production device according to claim 5, characterized in that: The upper insulating coupling (7.8) and the lower insulating coupling (7.12) are cylindrical structures, and the inner diameter of the upper insulating coupling (7.8) and the lower insulating coupling (7.12) is larger than the outer diameter of the conductive rod (7.9).

7. The deep-well heavy oil electric heating viscosity-reducing oil production device according to claim 6, characterized in that: The upper part of the live wire male connector (7.11) is a cylindrical structure, and the lower part is a truncated cone structure. The truncated cone structure of the lower part of the live wire male connector (7.11) extends to the lower end of the lower insulating coupling (7.12) and is movably connected to the inside of the live wire male connector (7.3) through the locking ring (7.6).

8. The deep-well heavy oil electric heating viscosity reduction oil production device according to claim 7, characterized in that: The cable passer (6) includes a cable passer tube (6.1), a cable passer outer protrusion (6.2), and a cable pass through hole (6.3). The cable passer tube (6.1) has a cable passer outer protrusion (6.2) on its middle outer wall. The cable pass through hole (6.3) is provided inside the cable passer outer protrusion (6.2). One end of the cable pass through hole (6.3) is connected to the inner cavity of the cable passer tube (6.1), and the other end is connected to the outer wall of the cable passer tube (6.1) along the cable passer outer protrusion (6.2).

9. The deep-well heavy oil electric heating viscosity-reducing oil production device according to claim 8, characterized in that: The upper end of the live wire connector (8.1) is cylindrical, and the lower end is located in the inner cavity of the neutral wire conductive tube (8.3). The outer diameter of the live wire connector (8.1) is smaller than the inner diameter of the neutral wire conductive tube (8.3). The upper end of the live wire connector (8.1) extends out of the neutral wire conductive tube (8.3) and passes through the lower insulating pad (7.4) of the upper cable insulation connecting tube (7) and is inserted into the inner cavity of the live wire mating connector (7.3).

10. A method of using the deep-well heavy oil electric heating viscosity-reducing oil production device as described in claim 9, characterized in that: Includes the following processes:

1. The oil pipe (10) is connected to the screw screen pipe (4), cable passer (6), cable insulation connection pipe (7), and downhole electric heater (8) and lowered into the casing (9). At the same time, the power cable (5) is lowered from the ground along the annulus between the oil pipe (10) and the casing (9) for a certain distance downhole, and then passes through the cable passer (6). The live wire and neutral wire are separated in the inner cavity of the cable passer (6). The live wire is connected to the conductive rod (7.9) through the lower inner plug (11) and the upper insulating coupling (7.8), and the neutral wire is connected to the conductor rod (7.9). The inner wall of the cable passer (6) contacts and the conductive rod (7.9) is wrapped by multiple sets of ceramic connecting cylinders (7.10) to realize the power relay connection of the deep well, so that the live wire is connected to the downhole electric heater (8) at the deep well along the cable insulation connecting pipe (7). The current circuit is connected to the neutral wire of the power transmission cable (5) through the neutral wire conductive pipe (8.3), electrode connector (7.2), and straight connecting pipe (7.1) in sequence through the inner wall of the cable passer (6). The lower end of the downhole electric heater (8) is close to the bottom of the artificial well (13).

2. Start the power supply on the ground and connect the power to the cable passer (6) in the well through the power transmission cable (5). Due to the conductive rod (7.9) in the cable insulation connection pipe (7) of the live wire, and the conductive rod (7.9) wrapped with multiple sets of ceramic connecting cylinders (7.10), the power relay of the deep well is realized. The cable insulation connection pipe (7) is used to withstand the high temperature, high pressure and corrosion of the deep well section, so that the heavy oil in the deep well is heated by the downhole electric heater (8) to increase the temperature and reduce the viscosity, which improves the fluidity of the oil. The oil enters the screw hole screen pipe (4) and drives the oil pump (2) through the sucker rod (1) to extract the oil to the surface.

3. If the viscosity of the heavy oil is reduced by heating, but the fluidity is still insufficient for the oil pump (2), the oil pump (2) is raised again, and the thin oil is injected into the well through the oil pipe (10) at the wellhead. The thin oil enters the casing (9) through the screw screen pipe (4). The viscosity of the heavy oil is reduced by the combination of the thin oil and the heating of the downhole electric heater (8), so that the fluidity of the oil meets the requirements for being extracted by the oil pump (2). The oil is then extracted to the surface by the oil pump (2).

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