Integrated multi-flow-state coupling underground permanent magnet electric pump

Abstract

The invention discloses an integrated multi-flow-state coupling underground permanent magnet electric pump, and relates to the technical field of oil field manual lifting exploitation. The integrated multi-flow-state coupling underground permanent magnet electric pump comprises a multi-flow-state coupling multi-stage centrifugal pump, an integrated submersible permanent magnet motor is installed on a flange at the bottom of the centrifugal pump, and a speed pipe expansion connector is installed on a flange at the top of the centrifugal pump. The inducer, the axial flow guide impeller and the mixed flow guide impeller are integrally mounted in the same centrifugal pump, the airlock problem of the centrifugal pump of the high-gas-content oil well is solved, the adaptability of the centrifugal pump to solid substances such as sand and wax is improved through the design that the impeller flow channel is wide and the discharge angle is small, and underground multi-flow-state stable and efficient mining is achieved; the motor efficiency and power density are improved through the design of the permanent magnet rotor, the motor length is shortened, the trafficability of an inclined shaft is improved, and energy conservation and consumption reduction are achieved; the capsule breathing device and the motor are integrated through the integrated design, and the drainage gas recovery function of the speed pipe column can be expanded through the speed pipe expansion connector.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial lift oilfield production, and more specifically, the present invention relates to an integrated multi-fluid state coupled downhole permanent magnet electric pump. Background Art

[0002] A submersible electric pump is an artificial lift device for downhole oil production in an oilfield, which consists of three parts: a downhole part, a surface part, and a middle power cable. The downhole part of the submersible electric pump is composed of a multistage centrifugal pump, an intake and treatment device, a protector, and a submersible motor, which plays the main role in pumping oil. The downhole part is lowered into the oil well together with the tubing. During operation, the ground power supply delivers electrical energy to the downhole submersible motor through the transformer, control cabinet, and power cable on the ground part. The submersible motor drives the multistage centrifugal pump to rotate, converting electrical energy into mechanical energy and lifting the well fluid in the oil well to the surface. Its downhole layout method from top to bottom is: multistage centrifugal pump, intake and treatment device, protector, submersible motor. The shafts of the four are connected by splines, and the outer shells of the four are connected by flanges. Some downhole sensors are also installed under the submersible motor, which can selectively measure changes in bottom hole pressure, temperature, etc., and transmit the signals to the surface control instrument through the power cable carrier wave method.

[0003] In recent years, the development of unconventional energy in China has been rapid. The recoverable reserves of shale oil are about 32 billion barrels, ranking third in the world; and the coalbed methane resources are extremely rich. In addition to shallow coalbed methane, the deep coalbed methane resources above 2,000 meters exceed 40 trillion cubic meters, and its potential will exceed shale gas. The annual increase in new energy oil and gas production has become a strong guarantee for national energy security. At present, the development of unconventional energy mainly adopts the method of long horizontal wells + hydraulic fracturing, and artificial lift equipment is required in the middle and late production stages. After the self-flowing stage of shale oil, artificial lift is needed to improve the recovery rate. Shale gas and coalbed methane need to quickly discharge fracturing water or groundwater, reduce reservoir pressure, and improve the desorption of formation methane. Submersible electric pumps have the characteristics of large displacement, high lift, maintenance-free, and no rod and pipe eccentric wear, and are widely used in the process of new energy development. With the increase in usage, the following problems have emerged in submersible electric pumps: high gas content, which is likely to cause gas lock in the centrifugal pump, reducing pump efficiency, causing vibration, and affecting heat dissipation; the presence of fracturing sand and formation sand, resulting in serious erosion and wear of the impeller of the centrifugal pump during the liquid drainage production process, and an increase in failure rate; high wax, gum, and asphaltene content in the well fluid, which is likely to cause blockage of the centrifugal pump and increase the motor load; the large wall thickness and small inner diameter of the oil well casing, and the large full angle change rate, resulting in poor passability of conventional submersible electric pumps, causing construction blockage, eccentric wear of the centrifugal pump, and cable extrusion. These problems reduce the operating life of submersible electric pumps and restrict the application of this technology.

[0004] Therefore, in view of the above, the inventor, with rich experience in design, development and actual production in the relevant industry for many years, studied and improved the structure and deficiencies of the existing submersible electric pump, and proposed an integrated multi-fluid-state coupled downhole permanent magnet electric pump, in order to achieve better passability in inclined wells; adaptability to multi-fluid states such as oil, water, gas, sand, wax, etc., and achieve the purpose of energy conservation and consumption reduction, improve the adaptability of submersible electric pumps to the exploitation and application of new energy, and promote the development of unconventional energy exploitation towards a cleaner, more efficient, lower-carbon and longer-life model. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention provides an integrated multi-fluid-state coupled downhole permanent magnet electric pump to solve the following problems encountered by the existing submersible electric pump when working in unconventional energy wells: large gas content, which is likely to cause gas lock in the centrifugal pump, reducing pump efficiency, causing vibration and affecting heat dissipation; the existence of fracturing sand and formation sand, resulting in serious erosion and wear of the guide impeller of the centrifugal pump during the liquid drainage production process, and an increase in failure rate; high content of wax, gum and asphaltene in the well fluid is likely to cause blockage of the centrifugal pump and increase the motor load; the wall thickness of the oil well casing is large, the inner diameter is small, and the full angle change rate is large, and the passability of the conventional submersible electric pump is poor, resulting in construction resistance, eccentric wear of the centrifugal pump and cable extrusion.

[0006] In order to achieve the above technical objectives and meet the above technical requirements, the technical solution adopted by the present invention is: an integrated multi-fluid-state coupled downhole permanent magnet electric pump, different from the conventional submersible electric pump unit, the downhole part is only composed of two parts, including a multi-fluid-state coupled multi-stage centrifugal pump and an integrated submersible permanent magnet motor. The bottom flange of the multi-fluid-state coupled multi-stage centrifugal pump is installed with an integrated submersible permanent magnet motor. The bottom flange of the integrated submersible permanent magnet motor is installed with a pressure sensor. The top of the integrated submersible permanent magnet motor is fixedly connected with a power cable. The top flange of the multi-fluid-state coupled multi-stage centrifugal pump is installed with a velocity tube expansion joint.

[0007] Preferably: the multi-fluid-state coupled multi-stage centrifugal pump includes a centrifugal pump head, a casing, a base, a pump shaft, an inducer, a mixed flow guide casing, a mixed flow impeller, an axial flow guide casing, an axial flow impeller, a locking component, and a wear-resistant component. The bottom of the base is an inclined surface, and a liquid suction port is provided on the inclined surface of the base.

[0008] Preferably: in the same section of the centrifugal pump, an inducer, an axial flow impeller, an axial flow guide casing, a mixed flow impeller, and a mixed flow guide casing are assembled in sequence from the suction port, and all the impellers are fixed to the pump shaft as a whole by a locking component.

[0009] Preferably: the guide impeller includes an axial flow impeller and a mixed flow impeller. The guide impeller is connected in series on the pump shaft. Multiple turbulence elimination ribs are designed at the fluid swirling contact parts of the axial flow guide casing and the mixed flow guide casing. The flow channel surfaces of the mixed flow guide casing, the mixed flow impeller, the axial flow guide casing, the axial flow impeller, and the inducer are all coated with an anti-scaling polymer coating.

[0010] Preferably, the locking assembly includes an upper half-ring, a locking nut, a locking screw, a pressing bushing, a shaft sleeve, and a lower half-ring. Half-ring grooves are provided at both the upper and lower ends of the pump shaft. The upper half-ring and the lower half-ring are installed in the half-ring grooves to limit all the impellers mounted on the pump shaft between the upper half-ring and the lower half-ring. The locking nut and the pressing bushing are connected by threads, and by rotating them in opposite directions, all the impellers between the upper half-ring and the lower half-ring are pressed against each other. The locking nut is provided with a screw hole.

[0011] Preferably, after all the impellers on the pump shaft are pressed by the locking assembly, the pump shaft and all the impellers can move up and down synchronously. The pump shaft is connected to the motor shaft through a spline sleeve to transfer the axial force on the pump shaft to the thrust bearing assembly of the integrated submersible permanent magnet motor.

[0012] Preferably, the wear-resistant assembly includes a bearing outer ring made of high-hardness material and a corresponding bearing inner ring made of high-hardness material. The two cooperate with each other to form a sliding friction pair. The hardness of the bearing outer ring and the bearing inner ring is higher than that of the formation sand. The bearing outer ring is inserted into the centrifugal pump head, the mixed-flow guide casing, the axial-flow guide casing, and the base by hot inlaying. The bearing inner ring should correspond to the bearing outer ring during assembly.

[0013] Preferably, a polymer coating is applied to all the surfaces of the inducer and the diffuser impeller that come into contact with the fluid. The coating can slow down the adhesion of scale.

[0014] Preferably, the integrated submersible permanent magnet motor includes a motor head, a capsule breathing assembly, a thrust bearing assembly, a motor shaft, a permanent magnet rotor, a motor stator, and a motor base. The motor base is provided with an oil injection hole for oil injection.

[0015] Preferably, the permanent magnet rotor includes rotor silicon steel sheets, a magnetic field generator, and locking tie bars. The rotor silicon steel sheets are of a stacked and riveted structure, with a hole in the middle and 4 groups of grooves in the circumferential direction. The magnetic field generator is installed in the reserved slot holes of the rotor silicon steel sheets and is closed at both ends with encapsulation covers. The locking tie bars are installed in the reserved slot holes of the rotor silicon steel sheets to fix the rotor silicon steel sheets to the designed length, and are fastened and installed at both ends by laser welding.

[0016] Preferably, the magnetic field generator is made of rare earth permanent magnet material, and its shape is straight sheet-like or arc-shaped. The straight sheet-like magnetic field generator is installed in the reserved slots of the rotor silicon steel sheets by an insertion installation method, and the arc-shaped magnetic field generator is installed on the surface of the rotor silicon steel sheets by an adhesive method.

[0017] Preferably, the capsule breathing assembly includes a capsule and a shaft protection tube. The two ends of the shaft protection tube are connected to the upper capsule seat and the lower capsule seat. The two ends of the capsule are respectively installed on the upper capsule seat and the lower capsule seat and are locked with metal clamps. The capsule is made of rubber.

[0018] Preferably, the thrust bearing assembly is shared by the integrated submersible permanent magnet motor and the multi-fluid-state coupled multi-stage centrifugal pump. The thrust bearing assembly includes a high-load static block, a bearing moving block, a moving block gland, and a half ring. A half-ring groove is provided on the motor shaft, and the half ring is installed in the half-ring groove. The moving block gland is provided with screw holes. The moving block gland, the half ring, and the bearing moving block are combined into one body by set screws. The high-load static block is a floating shoe structure static block, and the axial force of the multi-fluid-state coupled multi-stage centrifugal pump is transmitted to the high-load static block through a spline sleeve.

[0019] Preferably, the velocity string expansion joint includes a joint body, a sealing O-ring, a sealing sliding sleeve, and a compression spring. The joint body is provided with communication air inlet holes in the circumferential direction. The sealing O-ring, the sealing sliding sleeve, and the compression spring form a sealing sliding sleeve structure. Rubber ring grooves are respectively provided at both ends of the sealing sliding sleeve. Sealing O-rings are installed in the upper and lower rubber ring grooves of the sealing sliding sleeve. The compression spring is in a compressed state, and the communication air inlet holes are surrounded by the sealing O-rings at both ends in a sealed state. The sealing sliding sleeve has a matching insertion pipe. One end of the joint body is flange-connected, and the other end is connected by tubing threads. Communication air inlet holes are provided around the joint body.

[0020] Preferably, the insertion pipe is matched with the sealing sliding sleeve for sealing. The insertion pipe is inserted into the sealing sliding sleeve. When the sealing sliding sleeve moves downward, the compression spring contracts, and the communication air inlet holes provided in the circumferential direction of the joint body are opened.

[0021] Compared with the traditional structure, the beneficial effects of the present invention are as follows: 1. The present invention designs a new type of multi-fluid-state coupled multi-stage centrifugal pump applicable to high-gas-content oil wells. The inner channel of the centrifugal pump is divided into three sections. By setting an inducer in the inlet section to pre-pressurize the fluid in advance to increase the inlet pressure of the impeller and reduce the occurrence of cavitation. In the middle section, an axial-flow compression impeller is used to push the gas-liquid mixture to flow axially through the positions where gas locking is likely to occur in the previous stages. In the rear section, a mixed-flow guide impeller is used to break up and pressurize the bubbles in the mixed liquid, so that the gas and liquid are evenly mixed and mixed transportation is achieved, solving the gas locking problem of the centrifugal pump in high-gas-content oil wells. At the same time, the design of the large flow-through area and small outlet angle of the axial-flow and mixed-flow guide impeller channels has good passability for solid substances such as sand, wax, and asphaltenes in the well fluid, and normal and stable production under multiple fluid states such as oil, water, gas, sand, and wax can be realized.

[0022] 2. The present invention designs inner and outer ring friction pairs made of high-hardness materials inside the centrifugal pump. By utilizing the characteristic that the hardness of the friction pair is greater than the hardness of formation sand, the tolerance to sand abrasion is greatly improved. Through the turbulence elimination ribs designed in the guide casing, the high-frequency erosion of the guide casing by the turbulence of the sand-containing fluid is eliminated, reducing equipment wear, vibration, failure rate, and improving the service life.

[0023] 3. By setting the locking component to fix all the impellers and the pump shaft into one body, the present invention can ensure the synchronous up-and-down movement of the impellers and the pump shaft, and transfer the axial force of the impellers to the high-load bearing in the integrated motor through the pump shaft, ensuring that the impellers are always in a suspended state, avoiding the wear of the impeller gaskets, and thus protecting the normal operation of the centrifugal pump under the condition of deviating from the high-efficiency zone.

[0024] 4. The present invention redesigned the submersible motor through the design concept of the permanent magnet motor. By utilizing the characteristics of the permanent magnet rotor that does not require an excitation magnetic field, high efficiency, and high power factor, the design of small diameter and high power density of the submersible motor is realized, greatly shortening the length of the motor and further improving the passability of the downhole part of the submersible electric pump.

[0025] 5. Through the integrated design, the present invention realizes that the motor and the protector share a set of thrust systems. By utilizing the characteristics of the permanent magnet motor with low temperature rise and small breathing volume, the capsule breathing component is integrated with the motor to meet the functions of breathing and motor oil compensation, which not only shortens the length of the downhole part but also reduces the on-site docking and oil injection working time, improving the construction quality and the operation life of the unit.

[0026] 6. By configuring a velocity string expansion joint, the present invention realizes the extended application in shale gas and coalbed methane wells. For wells with a very high gas-liquid ratio, a thin tubing can be lowered into the existing tubing, and through the insertion tube at the lower part of the thin tubing, the annulus channel of the velocity string expansion joint is opened to realize the dual-channel operation of liquid drainage and velocity string drainage gas production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the overall structure of the present invention; Figure 2 is a schematic diagram of the structure of the multi-fluid-state coupling multistage centrifugal pump of the present invention; Figure 3 is a schematic diagram of the structure of the centrifugal pump locking component of the present invention; Figure 4 is a schematic diagram of the structure of the centrifugal pump wear-resistant component of the present invention; Figure 5 is a schematic diagram of the structure of the volute turbulence elimination of the present invention; Figure 6 is a schematic diagram of the structure of the velocity string expansion joint of the present invention; Figure 7 is a schematic diagram of the working structure of the opened velocity string expansion joint of the present invention; Figure 8 is a schematic diagram of the structure of the integrated submersible permanent magnet motor of the present invention; Figure 9 is a schematic diagram of the structure of the capsule breathing component of the integrated submersible permanent magnet motor of the present invention; Figure 10Schematic structural diagram of the thrust bearing assembly of the integrated submersible permanent magnet motor of the present invention; Figure 11 Schematic structural diagram of the permanent magnet rotor of the present invention.

[0028] The reference numerals are: 1, multi-fluid state coupling multi-stage centrifugal pump; 2, integrated submersible permanent magnet motor; 3, pressure sensor; 4, power cable; 5, velocity pipe expansion joint; 6, insertion pipe; 10, liquid suction port; 101, centrifugal pump head; 102, pump shaft; 103, housing; 104, mixed flow guide casing; 105, mixed flow impeller; 106, axial flow guide casing; 107, axial flow impeller; 108, inducer; 109, base; 110, compression pipe; 111, square key; 112, turbulence elimination rib; 8, locking assembly; 801, upper half ring; 802, locking nut; 803, locking screw; 804, compression bushing; 805, shaft sleeve; 806, lower half ring; 9, wear-resistant assembly; 901, bearing outer ring; 902, bearing inner ring; 20, cable connection port; 201, motor head; 202, mechanical seal; 203, connection section; 204, motor stator; 205, motor base; 206, oil injection valve; 207, rotor key; 208, motor shaft; 209, capsule housing; 210, one-way valve; 211, spline sleeve; 7, capsule breathing assembly; 701, capsule upper seat; 702, shaft protection tube; 703, capsule; 704, capsule lower seat; 705, metal clamp; 30, thrust bearing assembly; 301, set screw; 302, moving block gland; 303, moving block; 304, high-load static block; 305, half ring; 40, permanent magnet rotor; 401, encapsulation cover plate; 402, rotor silicon steel sheet; 403, locking tie bar; 404, magnetic field generator; 50, connecting air inlet hole; 501, joint body; 502, circlip; 503, sealing O-ring; 504, sealing sliding sleeve; 505, compression spring. Specific embodiments

[0029] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] Refer to the attached Figure 1, the present invention provides an integrated multi-flow-state coupled downhole permanent magnet electric pump, which includes a multi-flow-state coupled multi-stage centrifugal pump 1. A bottom flange of the multi-stage centrifugal pump 1 is installed with an integrated submersible permanent magnet motor 2. A bottom flange of the integrated submersible permanent magnet motor 2 is installed with a pressure sensor 3. A top of the integrated submersible permanent magnet motor 2 is fixedly connected with a power cable 4. A top flange of the multi-flow-state coupled multi-stage centrifugal pump is installed with a velocity tube expansion joint 5.

[0031] As shown in the appended Figure 2 to the appended Figure 5 , the multi-flow-state coupled multi-stage centrifugal pump 1 includes a centrifugal pump head 101, a pump shaft 102, a housing 103, a mixed-flow guide casing 104, a mixed-flow impeller 105, an axial-flow guide casing 106, an axial-flow impeller 107, an inducer 108, a base 109, a compression pipe 110, a square key 111, a locking assembly 8, and a wear-resistant assembly 9. The mixed-flow guide casing 104, the axial-flow guide casing 106, and the compression pipe are installed in the housing 103 in sequence. The centrifugal pump head 101 and the base 109 are connected to the housing 103 by threads and press all the internal components. The mixed-flow guide casing 104 and the axial-flow guide casing 106 are as Figure 5The shown design has turbulence elimination ribs 112, the height of the ribs is not less than 2 mm, the bottom of the base 109 is an inclined surface, and a liquid suction port 10 is provided on the inclined surface of the base 109. The flow passage surfaces of the mixed flow guide casing 104, the mixed flow impeller 105, the axial flow guide casing 106, the axial flow impeller 107, and the inducer 108 are all coated with a polymer coating, and they are all installed on the pump shaft 102 in the order from top to bottom. The pump shaft 102 drives them to rotate through a square key 111 to complete the suction and transportation of multi-flow state well fluid. The centrifugal pump locking assembly 8 is composed of an upper half ring 801, a locking nut 802, a locking screw 803, a pressing bushing 804, a shaft sleeve 805, and a lower half ring 806. A half ring groove is respectively opened at the upper and lower parts of the pump shaft 102. The upper half ring 801 and the lower half ring 806 are respectively installed in the half ring grooves to fix all the installed guide impellers on the pump shaft 102 within the range of the upper and lower half rings. A ring groove is opened on one side of the locking nut 802, and the upper half ring 801 is embedded in the ring groove. The pressing bushing 804 and the locking nut 802 are connected by threads. When the pressing bushing 804 and the locking nut 802 are rotated in opposite directions, the locking nut 802 presses the upper half ring 801 upward, the pressing bushing 804 presses the shaft sleeve 805 on the pump shaft downward, and presses the lower half ring 806 downward through all the impellers. The upper half ring 801 and the lower half ring 806 press the pump shaft 102 through the half ring grooves. In this way, the pump shaft 102 and all the impellers assembled on it are fixed as a whole. The locking screw 803 is installed in the screw hole of the locking nut 802 to prevent the locking nut 802 and the pressing bushing 804 from unthreading. The centrifugal pump wear-resistant assembly 9 includes a bearing outer ring 901 and a bearing inner ring 902. The bearing outer ring 901 is inserted into the centrifugal pump head 101, the mixed flow guide casing 104, the axial flow guide casing 106, and the base 109 by hot inlaying. One bearing inner ring 902 is inlaid every 3-5 stages of the guide casing. The bearing inner ring 902 is installed on the pump shaft 102 at a position corresponding to the bearing outer ring 901. The bearing inner ring 902 is driven to rotate by the pump shaft 102 through a square key 111 to form a pair of friction pairs with the bearing outer ring 901.

[0032] Specifically, first, the integrated submersible permanent magnet motor 2 rotates to drive the multi-fluid state coupled multi-stage centrifugal pump 1 to work. The multi-phase mixed liquid such as oil, water, and gas underground is sucked in from the liquid suction port 10 on the base 109, and the inducer 108 is used to pre-pressurize the fluid to increase the inlet pressure of the impeller and reduce the occurrence of cavitation phenomenon. Then, it is transported into the compression section composed of the axial flow impeller 107 and the axial flow guide vane 106. The axial flow compression impeller will push the multi-phase mixed liquid to flow axially through the positions where gas locking is likely to occur in the previous stages and further pressurize the mixed liquid before pushing it to the processing and transportation section composed of the mixed flow guide vane 104 and the mixed flow impeller 105. The specially designed mixed flow guide impeller breaks up and pressurizes the bubbles in the mixed liquid, making the gas-liquid uniformly mixed and realizing pressurized mixed transportation, thus solving the gas locking problem of the centrifugal pump in high gas-containing oil wells. At the same time, the flow passage cross-sectional areas of the axial flow and mixed flow guide vanes are large and the outlet angles are small, which has good passability for solid substances such as sand, wax, and asphaltene in the well fluid, and can realize normal and stable production under multi-fluid states such as oil, water, gas, sand, and wax. The locking assembly 8 fixes all the impellers and the pump shaft into one body, ensuring the synchronous up and down movement of the impeller and the pump shaft, and can transfer the axial force of the impeller to the high-load bearing in the integrated motor through the pump shaft, ensuring that the impeller is always in a suspended state, avoiding wearing the impeller gasket, and thus protecting the normal operation of the centrifugal pump under the state of deviating from the high-efficiency area. The wear-resistant components 9 are distributed in the multi-fluid state coupled multi-stage centrifugal pump 1 in proportion. Since the hardness of the outer ring 901 and the inner ring 902 of the bearing is higher than the hardness of the formation sand, the friction pair composed of them can greatly improve the sand abrasion tolerance of the centrifugal pump. Through the turbulence elimination ribs designed on the guide vane, the high-frequency erosion of the sand-containing fluid turbulence on the guide vane is eliminated, reducing equipment wear, vibration, failure rate, and improving the service life.

[0033] As shown in the appendix Figure 6 The speed tube expansion joint 5 includes a joint body 501, a circlip 502, a sealing O-ring 503, a sealing sliding sleeve 504, and a compression spring 505. One end of the joint body 501 is flange-connected and the other end is connected with a tubing thread. The air intake holes 50 are opened along the circumferential direction. The sealing sliding sleeve 504, the sealing O-ring 503, and the compression spring 505 form a sealing sliding sleeve assembly. The sealing O-ring 503 is installed in the rubber ring groove of the sealing sliding sleeve 504. The compression spring 505 and the sealing sliding sleeve 504 with the installed sealing O-ring are installed in the joint body 501 in the order from bottom to top, and the circlip 502 for the installation hole is installed on the upper part of the sealing sliding sleeve 504.

[0034] Specifically, during operation, the speed tube expansion joint 5 is flange-connected to the upper part of the multi-fluid state coupled multi-stage centrifugal pump 1. Figure 6The state shown is the state when the velocity tube expansion joint 5 is working normally. At this time, the compression spring 505 is in a compressed state, positioning the sealing sliding sleeve 504 in a state where the two-end sealing O-rings 503 surround and seal the communication air inlet hole 50. The well fluid discharged from the multi-fluid-state coupled multi-stage centrifugal pump 1 is discharged through the central hole of the sealing sliding sleeve 504. When the multi-fluid-state coupled multi-stage centrifugal pump 1 is applied to a high gas-containing oil well, the method of producing liquid carried by high-speed gas can be used for drainage gas production, saving energy and reducing consumption. During production, if Figure 7 , a small-diameter oil pipe with an inserted pipe 6 can be lowered into the crude oil pipe. The inserted pipe 6 is inserted into the sealing sliding sleeve 504 and pushes the compression spring 505 downward, vacating the communication air inlet hole 50 originally sealed by the two-end sealing O-rings 503. At this time, the high gas-containing well fluid will enter through the communication air inlet hole 50, and a high-speed gas flow will carry the formation fluid for production in the small-diameter flow channel.

[0035] As shown in the appendix Figure 8 to the appendix Figure 11 , the integrated submersible permanent magnet motor 2 includes: a motor head 201, a mechanical seal 202, a connection section 203, a motor stator 213, a permanent magnet rotor 204, a motor base 205, an oil injection valve 206, a rotor key 207, a motor shaft 208, a capsule housing 209, a check valve 210, and a spline sleeve 211.

[0036] The motor head 201, the capsule housing 209, the connection section 203, the motor stator 204, and the motor base 205 are connected by threads to form the frame of the integrated submersible permanent magnet motor 2. A mechanical seal 202 is installed inside the motor head 201 to seal the motor shaft 208 and prevent well fluid from entering. A check valve 210 is also installed inside the motor head 201 to achieve the one-way flow of the motor oil inside the motor. A cable connection port 20 is provided on the connection section 203 and is connected to a small flat cable connector to supply electrical energy to the motor. The capsule breathing assembly 7 includes a capsule upper seat 701, a shaft protection tube 702, a capsule 703, a capsule lower seat 704, and a metal clamp 705. The capsule 703 is made of rubber. The two ends of the shaft protection tube 702 are connected to the capsule upper seat 701 and the capsule lower seat 704. The two ends of the capsule 703 are installed on the capsule seats and are locked by the metal clamp 705. The thrust bearing assembly 30 is shared by the integrated submersible permanent magnet motor 2 and the multi-fluid-state coupled multistage centrifugal pump 1. Specifically, it includes a set screw 301, a moving block gland 302, a moving block 303, a high-load static block 304, and a half ring 305. A screw hole is provided on the moving block gland 302. The moving block gland 302, the half ring 305, and the bearing moving block 303 are combined into one body by the set screw 301. A half ring groove is provided on the motor shaft 208. The half ring 305 is installed in the half ring groove. The high-load static block 304 is installed inside the connection section 203. The axial force of the multi-fluid-state coupled multistage centrifugal pump 1 is transmitted to the high-load static block 304 through a spline sleeve 211. The permanent magnet rotor 40 is connected in series on the motor shaft 208. The weight of all the permanent magnet rotors 40 is transmitted to the moving block 303 through the half ring 305, and the thrust bearing is realized in cooperation with the high-load static block 304. The permanent magnet rotor 40 includes a packaging cover plate 401, rotor silicon steel sheets 402, locking tie bars 403, and a magnetic field generator 404. The rotor silicon steel sheets 402 are of a stacked and riveted structure, with a hole in the middle and 4 groups of grooves in the circumferential direction. The magnetic field generator 404 is installed in the reserved slot holes of the stator silicon steel sheets 402 and is closed at both ends by the packaging cover plate 401. The locking tie bars 403 are installed in the reserved slot holes of the stator silicon steel sheets 402 to fix the silicon steel sheets 402 to the designed length, and the two ends are fastened by laser welding. An oil injection valve 206 is installed on the motor base 205, and the motor oil inside the motor is injected from the oil injection valve 206 during motor operation.

[0037] Specifically, during operation, electrical energy is transmitted through the small flat cable connector at the cable connection port 20 to the windings of the motor stator 204. The windings generate a rotating magnetic field, and the magnetic field generator 404 within the permanent magnet rotor 40 generates its own magnetic field. The rotating magnetic field of the motor stator 204 captures the own magnetic field of the permanent magnet rotor 40 and drives the permanent magnet rotor 40 to rotate synchronously. The motor is filled with motor oil, and the mechanical seal 202 inside the motor head 201 can achieve the rotating dynamic seal of the motor shaft 208. When the motor operates, heat is generated and the temperature rises. The motor oil inside the motor stator 204 expands and enters the capsule 703 of the capsule breathing assembly through the channel of the connection section 203, and is exhaled through the one-way valve 210 inside the motor head 201; when the motor stops, the temperature drops, and the motor oil inside contracts, and the motor oil in the capsule 703 returns to supply the motor stator 204 along the original path.

[0038] Working principle of the present invention: Lower the integrated multi-fluid state coupled downhole permanent magnet electric pump to the designed position in the oil well as shown in Figure 1 . During operation, electrical energy is transmitted through the small flat cable connector at the cable connection port 20 to the windings of the motor stator 204. The windings generate a rotating magnetic field, and the magnetic field generator 404 within the permanent magnet rotor 40 generates its own magnetic field. The rotating magnetic field of the motor stator 204 captures the own magnetic field of the permanent magnet rotor 40 and drives the permanent magnet rotor 40 to rotate synchronously. The permanent magnet rotor 40 drives the motor shaft 208 to rotate. The motor shaft 208 drives the pump shaft 102 to rotate through the spline sleeve 211 and drives the inducer 108, axial flow impeller 107, and mixed flow impeller 105 to rotate and do work, transporting multi-fluid state well fluids such as oil, water, gas, sand, and wax in the well to the ground. When the oil well is for high gas content drainage gas production operation, the method of using high-speed gas to carry liquid production can be used for drainage gas production, saving energy and reducing consumption. During production, a small-diameter oil pipe with an insertion tube 6 can be lowered into the crude oil pipe. The insertion tube 6 is inserted into the sealing slip sleeve 504 and cooperates with it for sealing, pushing the compression spring 505 downward, allowing the original communication air inlet hole 50 sealed by the end sealing O-rings 503 to be vacated. At this time, the high gas content well fluid will enter through the communication air inlet hole 50 and form a high-speed gas flow in the small-diameter flow channel to carry the formation fluid for production.

[0039] In the attached drawings of the disclosed embodiments of the present invention, only the structures related to the disclosed embodiments are involved. For other structures, reference can be made to the general design. Without conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0040] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An integrated multi-flow state coupled downhole permanent magnet electric pump, comprising a multi-flow state coupled multistage centrifugal pump (1) and an integrated submersible permanent magnet motor (2), characterized in that: The bottom flange of the multi-flow-state coupled multistage centrifugal pump (1) is installed with an integrated submersible permanent magnet motor (2). The bottom flange of the integrated submersible permanent magnet motor (2) is installed with a pressure sensor (3). The top of the integrated submersible permanent magnet motor (2) is fixedly connected with a power cable (4). The top flange of the multi-flow-state coupled multistage centrifugal pump (1) is installed with a velocity tube expansion joint (5).

2. The integrated multi-flow-state coupled downhole permanent magnet electric pump according to claim 1, wherein: The multi-flow-state coupled multistage centrifugal pump (1) includes a centrifugal pump head (101), a housing (103), a base (109), a pump shaft (102), an inducer (108), a mixed-flow guide casing (104), a mixed-flow impeller (105), an axial-flow guide casing (106), an axial-flow impeller (107), a locking assembly (8), and a wear-resistant assembly (9). The bottom of the base (109) is inclined, and a liquid suction port (10) is provided in the inclined surface of the base (109). Starting from the suction port, an inducer (108), an axial-flow impeller (107), an axial-flow guide casing (106), a mixed-flow impeller (105), and a mixed-flow guide casing (104) are assembled in sequence within the same section of the centrifugal pump. The mixed-flow guide casing (104) and the axial-flow guide casing (106) are both designed with turbulence elimination ribs (112). The flow passage surfaces of the mixed-flow guide casing (104), the mixed-flow impeller (105), the axial-flow guide casing (106), the axial-flow impeller (107), and the inducer (108) are all coated with an anti-scaling polymer coating.

3. The integrated multi-flow-state coupled downhole permanent magnet electric pump according to claim 2, wherein: The locking assembly (8) includes an upper half-ring (801), a locking nut (802), a locking screw (803), a pressing bushing (804), a shaft sleeve (805), and a lower half-ring (806). Half-ring grooves are provided at both the upper and lower ends of the pump shaft (102). The upper half-ring (801) and the lower half-ring (806) are installed in the half-ring grooves to limit all the impellers installed on the pump shaft (102) between the upper half-ring (801) and the lower half-ring (806). The locking nut (802) and the pressing bushing (804) are connected by threads. By rotating them in opposite directions, all the impellers between the upper half-ring (801) and the lower half-ring (806) are pressed against each other.

4. The integrated multi-flow-state coupled downhole permanent magnet electric pump according to claim 2, wherein: After all the impellers on the pump shaft (102) are pressed by the locking assembly (8), the pump shaft (102) and all the impellers can move up and down synchronously. The pump shaft (102) is connected to the motor shaft (208) through a spline sleeve (211) to transfer the axial force on the pump shaft (102) to the thrust bearing assembly (30) of the integrated submersible permanent magnet motor (2).

5. The integrated multi-flow-state coupled downhole permanent magnet electric pump according to claim 2, wherein: The wear-resistant assembly (9) includes an outer bearing ring (901) and an inner bearing ring (902), which cooperate with each other to form a sliding friction pair. The hardness of the outer bearing ring (901) and the inner bearing ring (902) is higher than that of formation sand. The outer bearing ring (901) is inserted into the centrifugal pump head (101), the mixed-flow guide casing (104), the axial-flow guide casing (106), and the base (109) by hot inlay. The inner bearing ring (902) should correspond to the outer bearing ring (901) during assembly.

6. The integrated multi-flow-state coupled downhole permanent magnet electric pump according to claim 1, wherein: The integrated submersible permanent magnet motor (2) includes a motor head (201), a capsule breathing component (7), a thrust bearing component (30), a motor shaft (208), a permanent magnet rotor (40), a motor stator (204), and a motor base (205). The motor base (205) is provided with an oil injection hole for oil injection. The permanent magnet rotor (40) includes rotor silicon steel sheets (402), a magnetic field generator (404), and locking tie bars (403). The rotor silicon steel sheets are of a stacked and riveted structure, with a hole in the middle and 4 groups of slots opened in the circumferential direction. The magnetic field generator (404) is installed in the reserved slot holes of the rotor silicon steel sheets (402) and is closed at both ends with encapsulation cover plates (401). The locking tie bars (403) are installed in the reserved slot holes of the rotor silicon steel sheets (402) to fix the rotor silicon steel sheets (402) at the designed length, and are fastened by laser welding at both ends.

7. The integrated multi-flow-state coupled downhole permanent magnet electric pump according to claim 6, characterized in that: The capsule breathing component (7) includes a capsule (703). The two ends of the capsule (703) are respectively installed on a capsule upper seat (701) and a capsule lower seat (704) and are locked with a metal clamp (705). The material of the capsule (703) is rubber.

8. The integrated multi-flow-state coupled downhole permanent magnet electric pump according to claim 6, wherein: The thrust bearing component (30) is shared by the integrated submersible permanent magnet motor (2) and the multi-fluid-state coupled multi-stage centrifugal pump (1). The thrust bearing component (30) includes a high-load static block (304). The axial force of the multi-fluid-state coupled multi-stage centrifugal pump (1) is transmitted to the high-load static block (304) through a spline sleeve (211).

9. The integrated multi-fluid-state coupled downhole permanent magnet electric pump according to claim 1, characterized in that: The velocity pipe expansion joint (5) includes a joint body (501), a sealing O-ring (503), a sealing sliding sleeve (504), and a compression spring (505). The joint body (501) is provided with a communicating air inlet hole (50) opened in the circumferential direction. The sealing O-ring (503), the sealing sliding sleeve (504), and the compression spring (505) form a sealing sliding sleeve structure. Sealing O-rings (503) are respectively installed in the upper and lower rubber ring grooves of the sealing sliding sleeve (504) to surround the communicating air inlet hole (50) in a sealed state. The sealing sliding sleeve (504) is provided with a matching insertion pipe (6).

10. The integrated multi-flow-state coupled downhole permanent magnet electric pump according to claim 9, characterized in that: The insertion pipe (6) is in sealing cooperation with the sealing sliding sleeve (504). The insertion pipe (6) is inserted into the sealing sliding sleeve (504). When the sealing sliding sleeve (504) moves downward, the compression spring (505) contracts, and the communicating air inlet hole (50) opened in the circumferential direction of the joint body (501) is opened.

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