Power supply docking device of downhole power unit and oil extraction method

Abstract

The application relates to the technical field of oil exploitation, in particular to a power supply docking device of a downhole power unit and an oil extraction method, which comprises the following steps: an oil pipe is connected with a screw pump, an oil sucker rod is arranged in the oil pipe, the screw pump is provided with a submersible motor, and the oil sucker rod is installed with a cable; a docking assembly is arranged between the screw pump and the oil sucker rod, the docking assembly comprises a first docking rod and a second docking rod which are detachably connected, the first docking rod is connected with the submersible motor, and the second docking rod is connected with the oil sucker rod; an inner wall of the first docking rod is provided with a conductive ring, an outer wall of the second docking rod is provided with a conductive ring which is matched with the conductive ring, the conductive ring is connected with the submersible motor, and the conductive ring is connected with the cable; the conductive ring and the conductive ring are arranged to replace the excessively long cable, so that the cost and the risk of cable damage are reduced.

Description

Technical Field

[0001] This invention relates to the field of oil extraction technology, and in particular to a power supply connection device for a downhole power unit and an oil extraction method. Background Technology

[0002] In the field of oil extraction, screw pump oil production systems are widely used due to their good adaptability to high viscosity and sand-containing media. According to the arrangement of the drive motor, they are mainly divided into two types: surface drive and downhole drive.

[0003] In the surface-driven method, the wellbore inner wall is a casing, and the oil production equipment is installed inside the casing. The oil production equipment mainly includes tubing extending from the surface to the well, with the lower end of the tubing connected to the stator of the screw pump. The rotor of the screw pump is connected to the surface drive unit through the sucker rod. The motor is located on the surface and is connected to the downhole screw pump rotor through the sucker rod, which can be hundreds or even thousands of meters long, to transmit rotational power. This method is technically mature, but long shaft drives have problems such as large energy loss, rod string wear, and unsuitability for deviated and horizontal wells.

[0004] In downhole drive systems, the motor and screw pump are located together downhole and directly connected via short-shaft components such as an eccentric rod. This method eliminates the drawbacks of long-shaft drives and is particularly suitable for highly deviated and horizontal wells. However, downhole drive systems face a core challenge: the cable supplying power to the downhole motor needs to extend from the surface to depths of several thousand meters. Existing motor cable routing schemes suffer from the following main problems: (i) The cable is secured to the outer wall of the tubing with clamps and is lowered into the well along with the tubing, located in the annulus between the tubing and the casing. However, the cable is exposed in the annulus between the tubing and the casing, making it extremely susceptible to friction, compression, and collision with the casing wall during oil production, which can lead to damage to the cable insulation and breakage of the conductor. The downhole environment is complex, and once the cable is damaged, retrieval and repair operations are extremely difficult, costing up to tens of millions of yuan, and posing well control safety risks.

[0005] (ii) The cable passes through the inside of the tubing and reaches the well to connect with the motor. However, a single tubing can be several meters long. When going down into the well, it is necessary to pass each cable, which weighs several tons, through the tubing one by one and complete the joint connection. The operation is extremely cumbersome, labor-intensive, and has low construction efficiency. Moreover, the cable is easily damaged during the process of passing through the tubing.

[0006] (iii) Connecting downhole cable plugs using a retrieval tool. However, in deviated or horizontal wells, the retrieval device cannot guarantee precise alignment of the upper and lower plugs, resulting in a low success rate of connection. Furthermore, the small contact gap between the plugs makes them prone to short circuits in the conductive liquid environment downhole. Additionally, the high starting current of the motor can easily cause arcing and burn out the contacts if there is poor contact. Moreover, the lack of effective axial locking after connection makes it easy for the sucker rod to sway up and down during oil production, leading to poor contact. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a power supply docking device and oil production method for a downhole power unit, so as to solve one or more problems in the prior art.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: A power supply docking device for a downhole power unit, comprising: An oil pipe is connected to a screw pump, a sucker rod is installed inside the oil pipe, a submersible motor is installed in the screw pump, and a cable is installed on the sucker rod; A docking assembly is provided between the screw pump and the sucker rod. The docking assembly includes a first docking rod and a second docking rod that are detachably connected. The first docking rod is connected to the submersible motor, and the second docking rod is connected to the sucker rod. The inner wall of the first docking rod is provided with a conductive ring, and the outer wall of the second docking rod is provided with a conductive ring that matches the conductive ring. The conductive ring is connected to the submersible motor, and the conductive ring is connected to the cable.

[0009] By adopting the above technical solution, the screw pump is installed inside the well, and the tubing is installed above the screw pump. The submersible motor drives the screw pump to start, transporting oil from the tubing to the surface. The first connecting rod connects to the second connecting rod, thereby connecting the sucker rod to the submersible motor. At the same time, the conductive ring and conductive coil are connected and energized, and then the cable is connected to the submersible motor and energized. The cable is tied to the sucker rod, eliminating the need for each cable to pass through the tubing and complete the joint connection, shortening the connection distance between the cable and the submersible motor, reducing costs, and protecting the cable.

[0010] Furthermore, multiple conductive rings are provided, and they are all arranged along the axial direction of the first docking rod. The conductive rings are made of either beryllium copper alloy or phosphor bronze material, and the multiple conductive rings are insulated from each other. The conductive ring is provided with a plurality of conductive sheets distributed along its circumference, and the conductive sheets are electrically connected to the submersible motor through flexible wires.

[0011] By adopting the above technical solution, the terminals of the conductive ring are connected to the terminals of the submersible motor, so that the conductive ring and the submersible motor are energized without the need for excessively long cables.

[0012] Furthermore, the second docking rod has a hollow structure, and the conductive ring is made of either brass or copper. The conductive coils are provided in multiple quantities, the same as the number of conductive rings, and the multiple conductive coils are insulated from each other; The second connecting rod is frustum-shaped, and the semi-cone angle of the second connecting rod is 5°~30°; The first docking rod has a groove that matches the second docking rod, and the second docking rod can be rotatably inserted into the first docking rod.

[0013] By adopting the above technical solution, the outer wall of the second docking rod and the inner wall of the first docking rod are both frustoconical. Through the conical guide of the side wall, the second docking rod can be automatically aligned when it is rotated into the first docking rod, which effectively solves the problem of the difficulty in centering of traditional casting and retrieval devices in inclined and horizontal wells, and has a wider range of applications.

[0014] Furthermore, a docking screw is provided at one end of the second docking rod near the first docking rod, and a docking nut matching the docking screw is provided on the inner wall of the first docking rod, and the first docking rod and the second docking rod are threadedly connected.

[0015] By adopting the above technical solution, the threaded locking structure provides axial tension to the sucker rod, effectively suppressing the up-and-down swaying during the oil production process and ensuring the stability of electrode contact.

[0016] Furthermore, a wire-passing hole is provided at the end of the second docking rod, through which a cable can be inserted and extended into the second docking rod to be electrically connected to the plurality of conductive coils.

[0017] By adopting the above technical solution, the cable enters the second docking rod and connects with the conductive ring to conduct electricity, eliminating the need for direct connection to the submersible motor, thus reducing cable length and lowering costs.

[0018] Furthermore, the screw pump includes a stator connected to the oil pipe and a rotor rotatably disposed within the stator; The rotor is connected in sequence to an eccentric rod and a submersible motor at one end near the sucker rod.

[0019] By adopting the above technical solution, the eccentric rod eliminates the drawbacks of long shaft transmission in screw pumps, such as large energy loss, rod wear, and unsuitability for deviated and horizontal wells.

[0020] Furthermore, the conductive ring is elastic, with a radial compression of 0.5mm to 3mm, a radial contact pressure of 2N to 10N, a stiffness coefficient of 2N / mm to 10N / mm, a wall thickness of 0.5mm to 2mm, and a distance of 30mm to 40mm between adjacent conductive rings.

[0021] By adopting the above technical solution, the conductive ring has radial elasticity. When the first docking rod is connected to the second docking rod, the elasticity of the conductive ring is released and tightly connected to the conductive ring, thus avoiding disconnection.

[0022] Furthermore, an oil passage is provided at the end of the first connecting rod, and an air hole is provided on the side wall of the first connecting rod.

[0023] By adopting the above technical solution, the oil transported by the screw pump enters the oil pipe through the oil passage, and the air hole is used to balance the internal and external pressure difference to prevent oil from accumulating in the docking nut.

[0024] Furthermore, the submersible motor is connected to the oil pipe via a positioning connector, and the positioning connector has through holes evenly distributed along its circumference. The diameter of the through hole is 5mm to 30mm, the number of through holes is 3 to 8, and the total cross-sectional area of ​​the through holes is 0.2 to 0.7 times the cross-sectional area of ​​the oil pipe.

[0025] By adopting the above technical solution, a medium flow channel is formed between the through hole and the inside of the oil pipe, and oil enters the oil pipe through the through hole.

[0026] An oil production method for a downhole power unit, comprising a power supply connection device for a downhole power unit as described above, including: S1. The tubing, the screw pump, the submersible motor, and the first connecting rod are sequentially lowered into the well to a predetermined depth. The cable is tied to the sucker rod with oil-resistant cable ties. The end of the cable is inserted into the second connecting rod and connected to the terminal of the conductive ring by crimping or soldering. Then, the sucker rod with the cable tied and the connecting section assembled is sequentially lowered into the well. S2. When the second docking rod is lowered into the first docking rod, the sucker rod is slowly rotated on the ground by the sucker rod rotating device, which drives the second docking rod to rotate. The docking screw and the docking nut begin to mesh. Continue to rotate the second docking rod. The second docking rod moves downward under the action of the thread until the conductive ring abuts against the conductive ring, and the docking is completed. S3. Measure the insulation resistance of the three-phase windings of the motor to ground and the insulation resistance between the three phases on the ground to confirm that the cable and connection structure are intact. Then, conduct a short-term power-on test run, raising the voltage to 50% of the rated voltage and holding it for 5 seconds. Observe whether the three-phase current is balanced. After confirming that it is normal, oil extraction operations can be carried out.

[0027] By adopting the above technical solution, the cable is tied to the sucker rod. As the second connecting rod is connected to the first connecting rod, the conductive ring and the conductive coil are connected, thereby energizing the cable and the submersible motor to drive the screw pump to transport oil. This eliminates the need for excessively long cables, reducing costs and risks.

[0028] Compared with the prior art, the beneficial technical effects of the present invention are as follows: (i) This invention binds the cable to the sucker rod and lowers it in along with the sucker rod. The cable is located inside the tubing throughout the process, which completely avoids friction, squeezing and collision with the casing wall. This fundamentally eliminates the risk of cable wear and breakage, and greatly reduces maintenance costs and operational risks. At the same time, there is no need to perform cumbersome cable threading or binding operations at the wellhead, which significantly simplifies the construction process, reduces labor intensity and improves operational efficiency.

[0029] (ii) This invention uses a threaded mechanical connection and a tapered guide electrode to provide axial tension to the sucker rod through a threaded locking structure, achieving precise alignment and axial locking of the upper and lower components. This effectively suppresses the up-and-down swaying during oil production, ensures the stability of electrode contact, and effectively solves the problem of difficult alignment of traditional casting and retrieval devices in deviated and horizontal wells, thus having a wider range of applications.

[0030] (III) By adding a first docking component and a second docking component and optimizing the cable arrangement, this invention can be widely applied to various oil production equipment with cable arrangement problems in downhole power units, such as screw pumps and electric submersible centrifugal pumps. At the same time, the cable joints are isolated from the well fluid, avoiding long-term corrosion and fluid impact from media such as oil and natural gas, thus improving the life and reliability of the electrical connection.

[0031] (iv) The present invention uses an elastic conductive ring structure, in which the conductive ring releases its elastic force and tightly abuts against the conductive ring, ensuring continuous and low-resistance contact under vibration conditions, effectively preventing arcing and contact burnout caused by poor contact, and reducing the required cable length to reduce costs. Attached Figure Description

[0032] Figure 1 This invention provides a schematic diagram of the power supply docking device for a downhole power unit according to Embodiment 1 of the present invention. Figure 2 for Figure 1 A sectional view; Figure 3 A schematic diagram of the structure of the first connecting rod in Embodiment 1 of the present invention is shown; Figure 4 for Figure 3 A sectional view; Figure 5 A schematic diagram of the structure of the second connecting rod in Embodiment 1 of the present invention is shown; Figure 6 for Figure 2 Enlarged view of point A; Figure 7 A schematic diagram of the positioning connector of Embodiment 1 of the present invention is shown; Figure 8 for Figure 4 Another perspective view.

[0033] The following are labels in the attached diagram: 1. Oil pipe; 2. Screw pump; 21. Stator; 22. Rotor; 3. Submersible motor; 31. Positioning joint; 32. Through hole; 4. Eccentric rod; 5. Connecting assembly; 51. First connecting rod; 511. Conductive ring; 512. Connecting nut; 513. Oil passage hole; 514. Air hole; 52. Second connecting rod; 521. Conductive ring; 522. Connecting screw; 523. Wire passage hole; 6. Sucker rod. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the device proposed by this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, only for the purpose of conveniently and clearly illustrating the embodiments of this invention. Please refer to the drawings to make the objectives, features, and advantages of this invention more apparent and understandable. It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives achieved by this invention, should still fall within the scope of the technical content disclosed in this invention.

[0035] Accordingly, in specific embodiment 1, such as Figure 1 and Figure 2 As shown, this embodiment provides a power supply docking device for a downhole power unit, including: tubing 1, screw pump 2, submersible motor 3, docking assembly 5, and sucker rod 6; the screw pump 2 is vertically installed in the well, and the screw pump 2 includes a stator 21 connected to the tubing 1 and a rotor 22 rotatably installed in the stator 21, and the bottom of the tubing 1 is connected to the top of the stator 21 of the screw pump 2.

[0036] The sucker rod 6 is composed of multiple rods connected end to end. Cables are tied or embedded on the sucker rod 6, meaning the cables are installed on the surface or inside the sucker rod 6, and the sucker rod 6 transmits rotational torque. The output end of the submersible motor 3 is connected to the top of the rotor 22 of the screw pump 2 via an eccentric rod 4, and the submersible motor 3 is connected to the sucker rod 6 via a docking assembly 5.

[0037] In this embodiment, the submersible motor 3, eccentric rod 4, docking assembly 5, and sucker rod 6 are all installed inside the tubing 1, and the docking assembly 5 and sucker rod 6 are coaxially arranged with the screw pump 2. The eccentric rod 4 eliminates the drawbacks of the long shaft drive of the screw pump 2, such as large energy loss, rod string wear, and unsuitability for deviated and horizontal wells.

[0038] like Figure 6As shown, the docking assembly 5 is located between the screw pump 2 and the sucker rod 6. The docking assembly 5 includes a first docking rod 51 and a second docking rod 52 that are detachably connected. The first docking rod 51 and the second docking rod 52 are respectively connected to the submersible motor 3 and the sucker rod 6. By connecting the first docking rod 51 and the second docking rod 52, the sucker rod 6 is connected to the screw pump 2, and the screw pump 2 then transports oil to the discharge port.

[0039] like Figure 4 As shown, the inner wall of the first docking rod 51 is provided with a conductive ring 511, and the outer wall of the second docking rod 52 is provided with a conductive ring 521 that matches the conductive ring 511. The conductive ring 511 is connected to the submersible motor 3, and the conductive ring 521 is connected to the cable.

[0040] In this embodiment, multiple conductive rings 511 are provided, all arranged along the axial direction of the first connecting rod 51. The diameter of the multiple conductive rings 511 gradually decreases from top to bottom. The conductive rings 511 are made of beryllium copper alloy or phosphor bronze. The first connecting rod 51 is made of insulating material, and the multiple conductive rings 511 are insulated from each other. The surface of the conductive rings 511 can be silver-plated or gold-plated. The silver plating thickness is 3μm~5μm, and the gold plating thickness is 0.5μm~1μm, to reduce contact resistance and resist petroleum corrosion. Specifically, the terminals of the conductive rings 511 are electrically connected to the phase electrodes of the submersible motor 3, so that the conductive rings 511 and the submersible motor 3 are energized, eliminating the need for excessively long cables.

[0041] like Figure 5 As shown, the second docking rod 52 has a hollow structure, and the conductive rings 521 are made of brass or copper. Multiple conductive rings 521 are provided, the same number as the conductive rings 511, and the multiple conductive rings 521 are insulated from each other. The second docking rod 52 is frustoconical, and the semi-cone angle of the second docking rod 52, i.e., the angle between the generatrix and the vertical direction, is 5°~30°. If the semi-cone angle is too small, the guiding effect will be poor; if the semi-cone angle is too large, the axial force component will be too large, increasing the docking resistance. The second docking rod 52 is made of insulating material, such as polyetheretherketone (PEEK) or polytetrafluoroethylene (PTFE), which has oil resistance and high temperature resistance.

[0042] It should be noted that the diameter of the multiple conductive rings 521 gradually decreases from top to bottom. The first docking rod 51 has a groove that matches the second docking rod 52, allowing the second docking rod 52 to be rotatably inserted into the first docking rod 51. Simultaneously, the conductive ring 511 abuts against the conductive ring 521 and is energized. The inner wall of the first docking rod 51 and the outer wall of the second docking rod 52 are set as mutually mating conical surfaces, which play a mechanical guiding role during docking and reduce the centering accuracy requirements. Through the conical guidance of the side walls, the second docking rod 52 automatically centers when it rotates into the first docking rod 51, effectively solving the problem of difficult centering of traditional deployment and retrieval devices in inclined and horizontal wells, thus broadening its application range. The surface of the conductive ring 521 can be silver-plated with a thickness of 3μm~5μm, forming homogeneous contact with the silver plating layer of the elastic conductive ring 511, further reducing the contact resistance.

[0043] It should be noted that the second connecting rod 52 has a connecting screw 522 at its end near the first connecting rod 51, and the inner wall of the first connecting rod 51 has a connecting nut 512 that matches the connecting screw 522. The first connecting rod 51 and the second connecting rod 52 are threaded together. The second connecting rod 52 can be rotated downwards to enter the first connecting rod 51. The connecting screw 522 and the connecting nut 512 use large-pitch threads, such as rectangular threads, to achieve quick engagement. A torque sensor can be installed inside the sucker rod 6. When the torque of the sucker rod 6 is greater than a set value, the first connecting rod 51 and the second connecting rod 52 are locked, preventing over-tightening that could damage the components. The threaded locking structure provides axial tension to the sucker rod 6, effectively suppressing vertical swaying during oil production and ensuring the stability of electrode contact.

[0044] In this embodiment, the threads of the connecting screw 522 and the connecting nut 512 are preferably single-start, which has good self-locking performance and prevents loosening due to vibration. The thread fit adopts a medium fit grade, such as 7H / 6h, to prevent sand particles from getting stuck and causing the thread to jam. At the same time, the connecting screw 522 is made of alloy steel such as 40Cr or 42CrMo, with a hardness of HRC28-32, and the surface is phosphated or nickel-plated to improve wear resistance and corrosion resistance.

[0045] In addition, a wire hole 523 is provided at the end of the second docking rod 52. The cable can be inserted into the wire hole 523 and the second docking rod 52 to be electrically connected to multiple conductive rings 521. The cable is energized with the conductive rings 521, the conductive rings 521 are energized with the conductive rings 511, and the conductive rings 511 are energized with the submersible motor 3. Therefore, the cable is energized with the submersible motor 3 to supply power to the screw pump 2. There is no need for an excessively long cable to be directly connected to the submersible motor 3, which reduces cable costs and the risk of damage.

[0046] To improve stability, the conductive ring 511 is elastic, with a radial compression of 0.5mm to 3mm to accommodate the dimensional tolerances of the second docking rod 52 and thermal expansion and contraction caused by downhole temperature changes. The radial contact pressure is 2N to 10N, ensuring a contact resistance below 0.1 ohms while preventing excessive wear. The stiffness coefficient is 2N / mm to 10N / mm, and the wall thickness is 0.5mm to 2mm to ensure both elastic deformation capability and sufficient mechanical strength. The distance between adjacent conductive rings 511 is 30mm to 40mm to prevent short circuits caused by exposure of the conductive rings 511 to the oil mixture. The conductive ring 511 possesses radial elasticity; when the first docking rod connects to the second docking rod 52, the release of this elasticity tightly connects the conductive ring 511 with the conductive coil 521, preventing disconnection.

[0047] In addition, an oil passage hole 513 is provided at the end of the first connecting rod 51, and an air hole 514 is provided on the side wall of the first connecting rod 51. The oil transported by the screw pump 2 enters the oil pipe 1 through the oil passage hole 513, and the air hole 514 is used to balance the internal and external pressure difference and prevent oil from accumulating in the connecting nut 512.

[0048] In this embodiment, as Figure 7 As shown, the submersible motor 3 is connected to the oil pipe 1 through the positioning joint 31. The positioning joint 31 can be welded or threaded to the submersible motor 3 for fixation. The positioning joint 31 has through holes 32 evenly distributed along its circumference. The through holes 32 ensure the smooth passage of oil and other extracted media. The diameter of the through holes 32 is 5mm to 30mm, and the number of through holes 32 is 3 to 8 to ensure structural strength. The total cross-sectional area of ​​the through holes 32 is 0.2 to 0.7 times the cross-sectional area of ​​the oil pipe 1 to ensure sufficient flow capacity.

[0049] Given the continuous vibration and axial load fluctuations of the drive rod during downhole oil production, an anti-loosening structure is required at the threaded connection to prevent relative rotation between the connecting screw 522 and the connecting nut 512 after long-term operation, which could lead to poor electrical contact. Optionally, a wave spring washer or a disc spring washer can be placed between the end faces of the connecting nut 512 and the connecting screw 522. When the threads are fully engaged, the spring washer is compressed, providing a continuous axial preload to prevent the threads from loosening. The compression of the wave spring is set to 0.5mm~2mm, and the preload is set to 50N~200N.

[0050] In specific embodiment 2, based on embodiment 1, this embodiment provides an oil production method for a downhole power unit, employing a power supply connection device for the downhole power unit as described above, characterized in that it includes: S1. The tubing 1, screw pump 2, submersible motor 3 and first connecting rod 51 are sequentially lowered into the well to a predetermined depth. The cable is tied to the sucker rod 6 with oil-resistant cable ties. The end of the cable extends into the second connecting rod 52 and is connected to the terminal of the conductive ring 521 by crimping or soldering. Then the sucker rod 6 with the cable tied and the connecting section assembled is sequentially lowered into the well. S2. When the second docking rod 52 is lowered into the first docking rod 51, the sucker rod 6 is slowly rotated on the ground through the sucker rod rotating device, which drives the second docking rod 52 to rotate. The docking screw 522 and the docking nut 512 begin to mesh. Continue to rotate the second docking rod 52. The second docking rod 52 moves downward under the action of the thread until the conductive ring 511 abuts against the conductive ring 521, and the docking is completed. S3. Measure the insulation resistance of the three-phase windings of the motor to ground and the insulation resistance between the three phases on the ground to confirm that the cable and connection structure are intact. Then, conduct a short-term power-on test run, raising the voltage to 50% of the rated voltage and holding it for 5 seconds. Observe whether the three-phase current is balanced. After confirming that it is normal, oil extraction operations can be carried out.

[0051] In specific embodiment 3, the difference between this embodiment and embodiment 1 is that, as follows: Figure 8 As shown, the conductive ring 511 in this embodiment is open, with an opening width of 1mm to 3mm. Multiple circumferentially evenly distributed helical springs are disposed inside the conductive ring 511. One end of each helical spring abuts against the inner wall of the conductive ring 511, and the other end abuts against the first connecting rod 51, giving the conductive ring 511 a radially inward elastic preload, ensuring that it maintains tight contact with the second connecting rod 52 at all times, preventing circuit breakage. The helical spring wire diameter is 0.3mm to 0.8mm, the outer diameter is 3mm to 8mm, and the free length is 5mm to 15mm.

[0052] In specific embodiment 4, based on embodiment 1, this embodiment has three conductive rings 511 and three conductive coils 521, with each conductive ring 511 corresponding to one conductive coil 521. The conductive ring 511 is composed of multiple arc-shaped conductive plates. The power supply cable is a three-core armored cable, with the three core wires corresponding to the U, V, and W phases of the submersible motor 3, respectively. The current starts from the live wire of the ground power supply, travels downward along the cable core wires tied to the sucker rod 6, and enters the hollow cavity of the second docking rod 52. Since the cable and the conductive coil 521 are connected by crimping or welding, the current is conducted to the inner terminal of the conductive coil 521, and then conducted to its outer arc surface through the body of the conductive coil 521.

[0053] When the conductive coil 521 is connected to the conductive ring 511, each conductive coil 521 and its corresponding conductive ring 511 form an independent electrical path. Specifically, the outer arc surface of the conductive coil 521 forms an elastic contact with the outer wall of the conductive ring 511. The current crosses the contact interface, enters the conductive ring 511, and is then transmitted to the U-phase winding input terminal of the submersible motor 3 via the wire. The other two sets of conductive coils 521 and conductive rings 511 are similar.

[0054] In this embodiment, both the conductive ring 521 and the conductive coil 511 are metal surfaces and are silver-plated, giving the silver layer excellent conductivity and corrosion resistance. When the two metal surfaces of the conductive ring 521 and the conductive coil 511 are pressed together under the action of elastic preload, the microscopic protrusions on the contact interface undergo plastic deformation, forming multiple "conductive spots" where the metal and metal are in direct contact. The sum of these conductive spots constitutes the actual current channel.

[0055] In summary, the cable of the present invention is tied to the sucker rod 6. As the second connecting rod 52 is connected to the first connecting rod 51, the conductive ring 511 and the conductive coil 521 are connected, thereby energizing the cable and the submersible motor 3 to drive the screw pump 2 to transport oil. This eliminates the need for excessively long cables, reducing costs and risks.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A power supply docking device for a downhole power unit, characterized in that, include: Oil pipe (1), the oil pipe (1) is connected to a screw pump (2), a sucker rod (6) is installed inside the oil pipe (1), the screw pump (2) is equipped with a submersible motor (3), and the sucker rod (6) is equipped with a cable; The docking assembly (5) is located between the screw pump (2) and the sucker rod (6). The docking assembly (5) includes a first docking rod (51) and a second docking rod (52) that are detachably connected. The first docking rod (51) is connected to the submersible motor (3), and the second docking rod (52) is connected to the sucker rod (6). The inner wall of the first docking rod (51) is provided with a conductive ring (511), and the outer wall of the second docking rod (52) is provided with a conductive ring (521) that matches the conductive ring (511). The conductive ring (511) is connected to the submersible motor (3), and the conductive ring (521) is connected to the cable.

2. The power supply docking device for the downhole power unit as described in claim 1, characterized in that, Multiple conductive rings (511) are provided, and they are all arranged along the axial direction of the first docking rod (51). The conductive rings (511) are made of either beryllium copper alloy or phosphor bronze material, and the multiple conductive rings (511) are insulated from each other. The conductive ring (511) is provided with a plurality of conductive sheets distributed along its circumference, and the conductive sheets are electrically connected to the submersible motor (3) through flexible wires.

3. The power supply docking device for the downhole power unit as described in claim 2, characterized in that, The second docking rod (52) has a hollow structure, and the conductive ring (521) is made of either brass or copper. Multiple conductive rings (521) are provided, and the number is the same as that of conductive rings (511). The multiple conductive rings (521) are insulated from each other. The second connecting rod (52) is frustum-shaped, and the semi-cone angle of the second connecting rod (52) is 5°~30°; The first docking rod (51) has a groove that matches the second docking rod (52), and the second docking rod (52) can be rotatably inserted into the first docking rod (51).

4. The power supply docking device for the downhole power unit as described in claim 1, characterized in that, The second docking rod (52) is provided with a docking screw (522) at one end near the first docking rod (51), and the inner wall of the first docking rod (51) is provided with a docking nut (512) that matches the docking screw (522). The first docking rod (51) and the second docking rod (52) are threadedly connected.

5. The power supply docking device for the downhole power unit as described in claim 3, characterized in that, The end of the second docking rod (52) has a wire hole (523). The cable is inserted into the wire hole (523) and extends into the second docking rod (52) to be electrically connected to the multiple conductive rings (521).

6. The power supply docking device for the downhole power unit as described in claim 1, characterized in that, The screw pump (2) includes a stator (21) connected to the oil pipe (1) and a rotor (22) rotatably disposed within the stator (21); The rotor (22) is connected in sequence to an eccentric rod (4) and a submersible motor (3) at one end near the sucker rod (6).

7. The power supply docking device for the downhole power unit as described in claim 2, characterized in that, The conductive ring (511) is elastic, the radial compression of the conductive ring (511) is 0.5mm~3mm, the radial contact pressure is 2N~10N, the stiffness coefficient is 2N / mm~10N / mm, the wall thickness is 0.5mm~2mm, and the distance between adjacent conductive rings (511) is 30mm~40mm.

8. The power supply docking device for the downhole power unit as described in claim 1, characterized in that, An oil hole (513) is provided at the end of the first connecting rod (51), and an air hole (514) is provided on the side wall of the first connecting rod (51).

9. The power supply docking device for the downhole power unit as described in claim 2, characterized in that, The submersible motor (3) is connected to the oil pipe (1) through a positioning joint (31), and the positioning joint (31) is provided with through holes (32) evenly distributed along its circumference. The diameter of the through hole (32) is 5mm to 30mm, the number of through holes (32) is 3 to 8, and the total cross-sectional area of ​​the through holes (32) is 0.2 to 0.7 times the cross-sectional area of ​​the oil pipe (1).

10. A method for oil production from a downhole power unit, comprising a power supply connection device for a downhole power unit as described in claims 1-9 above, characterized in that, include: S1. The tubing (1), the screw pump (2), the submersible motor (3) and the first connecting rod (51) are sequentially lowered into the well to a predetermined depth. The cable is tied to the sucker rod (6) with oil-resistant cable ties. The end of the cable is inserted into the second connecting rod (52) and connected to the terminal of the conductive ring (521) by crimping or soldering. Then the sucker rod (6) with the cable tied and the connecting section assembled is sequentially lowered into the well. S2. When the second docking rod (52) is lowered into the first docking rod (51), the sucker rod (6) is slowly rotated on the ground by the sucker rod rotating device, which drives the second docking rod (52) to rotate. The docking screw (522) and the docking nut (512) begin to mesh. Continue to rotate the second docking rod (52). The second docking rod (52) moves downward under the action of the thread until the conductive ring (511) abuts against the conductive ring (521), and the docking is completed. S3. Measure the insulation resistance of the three-phase windings of the motor to ground and the insulation resistance between the three phases on the ground to confirm that the cable and connection structure are intact. Then, conduct a short-term power-on test run, raising the voltage to 50% of the rated voltage and holding it for 5 seconds. Observe whether the three-phase current is balanced. After confirming that it is normal, oil extraction operations can be carried out.

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