Testing system and method special for testing oil field gas-liquid mixed transportation type electric submersible pump

Abstract

According to the test system and method special for testing the gas-liquid mixed transportation type electric submersible pump in the oil field, tests do not need to be conducted on a real oil well, various basic tests of gas-liquid mixed transportation can be completed on site in a factory, and the working condition environments of different oil wells are directly simulated. The system comprises a simulation test shaft filled with crude oil simulation liquid and provided with a sealed wellhead, and underground equipment to be tested is arranged in the simulation test shaft and completely immersed in the crude oil simulation liquid; the transformer and the control cabinet are connected, and the control cabinet is connected to underground equipment to be tested through a submersible cable; the underground equipment to be tested is communicated to the liquid temporary storage tank through an oil pipe, and a throttle valve is arranged on the oil pipe; the liquid temporary storage tank is communicated into the simulation test shaft through a pipeline a, and the pipeline a is provided with a ground liquid delivery pump; the device further comprises a gas temporary storage tank filled with non-condensable gas, the gas temporary storage tank is communicated to the bottom of the simulation test shaft through a gas conveying pipe, and a compressor and a regulating valve are arranged on the gas conveying pipe.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil well production fluid lifting in the oilfield mining industry, and relates to a design verification test method, specifically a test system and method specially used for testing oilfield gas-liquid mixed transmission type submersible electric pumps. Background Art

[0002] Submersible electric pumps are specialized equipment used in oilfield production, lifting crude oil from underground wells to the surface. These devices offer long maintenance-free cycles, eliminating the frequent downtime associated with rod pumps. In recent years, they have gained widespread adoption both domestically and internationally. Currently, conventional submersible electric pumps are generally only suitable for wells with low natural gas content, typically no more than 30%. National standards do not recommend their use if the gas content exceeds this range.

[0003] However, in reality, many oil wells produce high amounts of natural gas. While natural gas doesn't readily precipitate from the crude oil produced fluid under the high pressure created by the downhole liquid column, the amount of released gas can still exceed the recommended range when the concentration is high. Centrifugal submersible pumps, however, operate at speeds of up to around 3,000 rpm. High levels of natural gas in the crude oil can significantly impact the pump's performance and lifespan. This gas release discontinuously causes fluid flow, leading to chopped flow and severe load fluctuations. This can cause significant current fluctuations in the motor, potentially leading to motor burnout. Excessive gas levels can even disrupt the pump's flow, causing a gas lock and complete loss of lift capacity, which can easily damage the equipment. To prevent damage to the submersible pump from gas contained in the crude oil produced fluid, conventional submersible pumps are typically equipped with a gas-liquid separator. This separator, located below the pump's intake, centrifugally separates the gas into the wellbore, preventing damage to the centrifugal pump. However, the separation effect of existing general separators is limited. When the gas content is higher than 30%, the separation effect cannot be guaranteed. Therefore, in this case, the use of submersible electric pumps is not recommended, which seriously affects the application and promotion of this convenient equipment.

[0004] In recent years, several research efforts have addressed this issue. For example, studies using multi-stage separators have shown that separation capacity can be increased to 50% gas content. Other research is underway on submersible pumps for mixed gas-liquid transmission. Using a specialized pump blade design, a gas-liquid pump is connected in series with a conventional submersible pump. This pre-disperses any remaining gas, breaking up bubbles and preventing them from escaping. The pump then transports the gas along with the liquid, preventing gas lock. Reports suggest that these devices can transport crude oil with gas content of 70-80%. While most of these new devices are still in the research and trial application stages, they hold great promise for widespread application.

[0005] However, there are currently no suitable testing, assessment, and verification methods for conducting research related to gas separation and gas-liquid mixed transmission. Developed products can only be tested downhole, which is expensive and often involves numerous uncontrollable factors, making the work difficult. Furthermore, the biggest challenge with downhole testing is that the downhole conditions at each well are typically fixed, allowing only one operating condition to be tested at a time without the ability to adjust. Furthermore, if a test fails, the resulting economic losses from production downtime are significant, making oilfield operators generally unwilling to take this risk. This often hinders equipment R&D teams from finding suitable test wells, hindering the development and improvement of new products. Summary of the Invention

[0006] In view of the current situation that it is difficult to test and verify gas-liquid mixed transmission submersible electric pumps, the present invention proposes a test system and method specifically for testing gas-liquid mixed transmission submersible electric pumps in oil fields. There is no need to conduct tests on actual oil wells. Various basic tests of gas-liquid mixed transmission can be completed on-site in the factory, directly simulating the working conditions of different oil wells and allowing for flexible adjustments.

[0007] The technical solution adopted by the present invention to solve its technical problems is:

[0008] A test system specifically for testing gas-liquid mixed transmission submersible electric pumps in oil fields, comprising a simulated test wellbore filled with crude oil simulation liquid and having a sealed wellhead, wherein downhole equipment to be tested is placed in the simulated test wellbore and completely immersed in the crude oil simulation liquid, wherein the downhole equipment to be tested includes a submersible motor, a motor protector, an oil-gas separator, and a gas-liquid mixed transmission submersible pump; further comprising a connected transformer and a control cabinet, wherein the control cabinet is connected to the downhole equipment to be tested via a submersible cable to adjust the power supply for the downhole equipment to be tested; the downhole equipment to be tested is connected to a liquid temporary storage tank via an oil pipe, and the oil pipe is provided with a a throttle valve; a liquid temporary storage tank is connected to the simulated test wellbore through pipeline a, and an uphole liquid delivery pump is provided on pipeline a for circulating the liquid in the liquid temporary storage tank into the simulated test wellbore; it also includes a gas temporary storage tank filled with non-condensable gas, which is connected to the bottom of the simulated test wellbore through a gas delivery pipe to simulate downhole natural gas, and a compressor and a regulating valve are provided on the gas delivery pipe; pressure gauges and safety valves are installed on the top of the liquid temporary storage tank, the top of the gas temporary storage tank, and the top of the sealed wellhead; it also includes a variety of sensors and meters for monitoring equipment and pipeline parameters.

[0009] Furthermore, it also includes at least one group of gas cylinders connected to the gas temporary storage tank through pipeline b, which is used to replenish gas into the gas temporary storage tank, and another throttle valve is provided on pipeline b.

[0010] Furthermore, the various sensors and meters specifically include: a liquid flow meter installed on pipeline a for measuring the liquid input flow, a gas flow meter installed on the gas transmission pipe for measuring the gas input flow, a gas-liquid two-phase flow meter installed on the oil pipe for measuring the crude oil simulation liquid output flow, a current sensor installed on the submersible cable for measuring the three-phase current fluctuation value of the submersible motor, and a vibration sensor connected to the gas-liquid mixed transmission submersible pump for measuring its vibration.

[0011] Furthermore, a separation element for gas-liquid separation is provided in the liquid temporary storage tank, and a vent valve is provided on the top of the liquid temporary storage tank.

[0012] Furthermore, a sampler is installed on the oil pipe for discharging and sampling fluid.

[0013] Furthermore, the sealed wellhead, simulated test wellbore, liquid temporary storage tank, gas temporary storage tank, gas cylinder and various connecting pipelines are all pressure-bearing components, and the pressure resistance design value is 1-5MPa.

[0014] A test method specifically for testing a gas-liquid mixed transmission submersible electric pump in an oil field is also provided, the steps comprising:

[0015] Place the downhole equipment to be tested in the simulated test wellbore, connect the submersible motor to the transformer and control cabinet through submersible cables, and perform reliable insulation and sealing.

[0016] Start the on-hole liquid delivery pump and inject the crude oil simulation liquid in the liquid temporary storage tank into the simulated test wellbore until the downhole equipment to be tested is completely immersed and there is sufficient submergence and a stable liquid surface;

[0017] Power on the downhole equipment to be tested to start operation. During operation, adjust the throttle valve opening on the oil pipe to simulate the pump head; adjust the submersible motor to simulate the pump output;

[0018] Synchronously adjust the speed of the liquid delivery pump on the well until the output flow rate of the crude oil simulation liquid is basically the same as the liquid flow rate of the crude oil simulation liquid injected from the liquid temporary storage tank into the simulation test wellbore. At this time, the liquid delivery process of the gas-liquid mixed transmission submersible pump reaches a steady state. Circulate in this state for a period of time to stabilize the system.

[0019] Start the compressor and inject the gas in the gas storage tank into the bottom of the well through the gas transmission pipe. The flow rate is controlled by the regulating valve. After the gas flow rate reaches the predetermined design flow rate, it maintains stable operation.

[0020] At this time, the downhole equipment to be tested in the simulated test wellbore is in a gas-liquid mixed transmission operation state. The gas-liquid two-phase flow transported to the ground by the gas-liquid mixed transmission submersible pump is transported back to the liquid temporary storage tank. After being separated by the separation element in the liquid temporary storage tank, the gas is released into the atmosphere through the vent valve on the top of the tank, and the liquid continues to circulate to the simulated test wellbore for use.

[0021] Furthermore, a portion of the fluid is periodically released through a sampler installed on the oil pipe and discharged into a transparent container with a volume scale and weighing function to analyze the actual gas-liquid ratio in the gas-liquid two-phase flow and the separation state of the bubbles.

[0022] Furthermore, the three-phase current fluctuation value of the submersible motor is monitored by the current sensor, and the vibration sensor is used to measure the vibration of the gas-liquid mixed transmission submersible pump. The control cabinet receives the current sensor and vibration sensor signals to monitor the current fluctuation or vibration value. If it exceeds the pre-set value, the control cabinet will first automatically reduce the frequency and reduce the speed of the submersible motor. If it still cannot be improved, the machine will be shut down and an alarm will be issued.

[0023] Furthermore, the operation test was run continuously for 24 hours to 240 hours.

[0024] The beneficial effects of the present invention include:

[0025] The present invention provides an operational test system and method for a gas-liquid mixed transmission submersible electric pump. This system eliminates the need for testing on actual oil wells; instead, various basic gas-liquid mixed transmission tests can be completed on-site within the factory. This directly simulates the operating conditions of different oil wells and allows for flexible adjustments. This test can be used to assess the feasibility and rationality of the designed and manufactured gas-liquid mixed transmission submersible electric pump equipment. This system has excellent practical value for accelerating the development cycle of new gas-liquid mixed transmission submersible electric pumps and reducing testing costs. Furthermore, the present invention can also serve as a factory test method for finalized gas-liquid mixed transmission submersible electric pump products, allowing for factory inspection of the products. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall composition structure of the system of the present invention.

[0027] In the figure: 1. Submersible motor; 2. Motor protector; 3. Oil-gas separator; 4. Gas-liquid mixed transmission submersible pump; 5. Submersible cable; 6. Crude oil simulation liquid; 7. Oil pipe; 8. Control cabinet; 9. Transformer; 10. Simulated test wellbore; 11. Liquid temporary storage tank; 12. On-well liquid delivery pump; 13. Liquid flow meter; 14. Gas temporary storage tank; 15. Compressor; 16. Gas flow meter; 17. Gas delivery pipe; 18. Gas cylinder; 19. Gas-liquid two-phase flow meter; 20. Sampler; 21. Current sensor; 22. Vibration sensor; 23. Safety valve; 24. Pressure gauge; 25. Vent valve; 26. Throttle valve; 27. Control valve; 28. Pressure gauge a; 29. ​​Control valve a; 30. Separation element; 31. Sealed wellhead. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] The present invention proposes a test system and method for testing a gas-liquid mixed transmission submersible electric pump in oil fields. The system structure corresponding to the test is shown in FIG. Figure 1The system includes at least one simulated test wellbore 10 with a sealed wellhead 31 and filled with crude oil simulant 6. The depth of the simulated test wellbore 10 is sufficient to accommodate all downhole equipment to be tested, ensuring that all components are submerged in the crude oil simulant 6 and that a certain degree of submergence and a stable liquid level are maintained during the test. Before the test, the downhole equipment to be tested (including the submersible motor 1, motor protector 2, oil-gas separator 3, gas-liquid mixed transmission submersible pump 4, etc.) is pre-placed in the simulated test wellbore 10. The wellbore is filled with crude oil simulant 6, and the sealed wellhead 31 is sealed. During the test, the downhole equipment to be tested is powered by a transformer 9. After the control cabinet 8 adjusts parameters such as frequency, current, and voltage, power is then supplied to the downhole equipment to be tested via a submersible cable 5. After the downhole equipment to be tested is started, the extracted liquid flows along the oil pipe 7, passes through the liquid temporary storage tank 11, and is then re-injected into the simulated test wellbore 10 by the uphole liquid delivery pump 12, achieving recycling. A temporary gas storage tank 14 is also provided, filled with non-condensable gas, such as nitrogen or argon, which does not burn or support combustion. This gas is used to simulate natural gas downhole, providing a gas medium for the gas-liquid pump being tested. The gas in the temporary gas storage tank 14 is pressurized by a compressor 15 and then directly injected into the bottom of the simulated test wellbore 10 through a pre-buried gas delivery pipe 17 parallel to the simulated test wellbore 10. During the process of rising, these gases can be sucked into the pump port of the gas-liquid mixed transmission submersible pump 4 along with the crude oil simulation liquid 6. The flow rate of the input gas is adjusted by a regulating valve 27. The pressure of the gas injected into the wellbore must be higher than the liquid column pressure at the bottom of the simulated test wellbore 10. The pressure required for its delivery is provided by the compressor 15. Pressure gauges 24 and safety valves 23 are installed at the top of the liquid temporary storage tank 11 and the gas temporary storage tank 14, as well as at the top of the sealed wellhead 31 to ensure safety requirements. Because the gas in the temporary gas storage tank 14 used in the test is consumable, a set of gas cylinders 18 is also provided to continuously replenish the temporary gas storage tank 14. The test system is also equipped with various sensors and meters, including a liquid flowmeter 13 for measuring the liquid input flow rate, a gas flowmeter 16 installed on the gas delivery pipe 17 for measuring the gas input flow rate, a gas-liquid two-phase flowmeter 19 installed on the oil pipe 7 for measuring the output flow rate of the crude oil simulation liquid, a current sensor 21 installed on the submersible cable 5 for measuring the three-phase current fluctuation value of the submersible motor 1, and a vibration sensor 22 connected to the gas-liquid mixed transmission submersible pump 4 for measuring its vibration.

[0031] A separation element 30 for gas-liquid separation is provided in the liquid temporary storage tank 11, and a vent valve 25 is provided on the top of the liquid temporary storage tank 11. A sampler 20 is also installed on the oil pipe 7 for discharge sampling of the fluid.

[0032] The test system's operating process is as follows: ① Before the system begins operation, the downhole portion of the gas-liquid mixed transmission submersible electric pump to be tested is placed in a simulated test wellbore 10. The submersible motor 1 is connected to the control cabinet 8 and transformer 9 via a submersible cable 5, and the submersible motor 1 is reliably insulated and sealed. ② The uphole liquid delivery pump 12 is started, and crude oil simulation liquid 6 from the liquid temporary storage tank 11 is injected into the wellbore until the downhole equipment to be tested is completely submerged, with sufficient submergence and a stable liquid level. ③ The downhole equipment to be tested is powered on to start operation. During this process, the opening of the throttle valve 26 on the oil pipe 7 is adjusted to create a certain outlet pressure due to the resistance of the liquid flow, simulating the pump's head. By adjusting the speed of the submersible motor 1, the output flow of the gas-liquid mixed transmission submersible pump 4 can be changed, simulating the pump's output, which is measured by the gas-liquid two-phase flowmeter 19. To ensure a balanced total downhole liquid volume, the speed of the surface liquid delivery pump 12 must be adjusted synchronously, and the readings of the gas-liquid two-phase flowmeter 19 and the liquid flowmeter 13 must be monitored until they are essentially equal. At this point, the submersible pump's liquid delivery process reaches a steady state. ④ Circulate within this state for a period of time to ensure system stability. ⑤ Start the compressor 15, injecting gas from the gas storage tank 14 into the bottom of the well via the delivery pipe 17, with the flow rate controlled by the regulating valve 27. Once the gas flow reaches the predetermined design flow rate, stable operation is maintained. ⑥ At this point, the submersible pump in the wellbore is operating in a mixed gas-liquid flow mode. The gas-liquid two-phase flow delivered to the surface by the mixed gas-liquid delivery submersible pump 4 is transported back to the liquid storage tank 11. After separation by the separation element 30 within the tank, the gas is released to the atmosphere through the vent valve 25 on the tank top, while the liquid continues to be recycled. ⑦ To determine the actual gas-liquid ratio and bubble separation within the gas-liquid two-phase flow, a sampler 20 is installed on the output oil pipe 7 to periodically release a portion of the fluid. This fluid is discharged into a transparent container with a volume scale and weighing function. The fluid density can be measured and calculated, converted into a gas content ratio. The state of the bubbles can also be observed, and the gas distribution pattern analyzed. ⑧ The injection of large amounts of gas into the liquid flow can cause instability in the submersible pump equipment and potentially damage the equipment. Therefore, a current sensor 21 is installed on the transmission line to measure three-phase current fluctuations. A vibration sensor 22 is also installed on the gas-liquid mixed transmission submersible pump 4 to measure equipment vibration and transmit the signal to the control cabinet 8 in a timely manner. If the fluctuation or vibration value exceeds a preset value, the control cabinet will first automatically reduce the motor speed. If this does not improve, a shutdown alarm will be issued. ⑨ Because the injection of gas into the liquid flow inevitably causes an increase in pressure, the wellbore, wellhead, tank, and pipeline in this system are all pressure-bearing components. The design pressure resistance value should be between 1 and 5 MPa, depending on the specific process requirements. ⑩ The above operating tests should be conducted continuously. Depending on the needs of the equipment assessment, continuous operation for 24 to 240 hours is generally considered.During the test, if the gas cannot be promptly transported by the gas-liquid pump, it will inevitably float up and accumulate above the wellbore. This will gradually cause the wellbore fluid level to drop and the wellhead casing pressure to rise, ultimately leading to drastic fluctuations in equipment parameters and even tripping the safety valve. This indicates that the gas-liquid pump's delivery capacity has been exceeded, and the design should be revised and the test repeated. If the test proceeds smoothly, after the test is completed, vent the system pressure, open the wellhead, and remove the gas-liquid mixed transmission submersible electric pump from the well. Alternatively, the pump can be disassembled to observe any damage and improve the design.

[0033] The method proposed in the present invention, after gradual improvement and promotion, can also become a universal test method, serving as the basis for the acceptance and assessment of such products.

[0034] Example 1

[0035] A set of designed displacement of 30m in an oil field 3 / day, a gas-liquid mixed transmission submersible electric pump with a head of 3000m, a submersible motor with a power of 80kw, an outer diameter of 114mm, an outer diameter of 98mm for the submersible pump, and a total length of 35m for the downhole equipment. The equipment was tested using the test method proposed in the present invention. The simulated oil well depth used in the test was 60m, the crude oil simulation liquid was thermal oil, and the mixed transmission gas was nitrogen. In the test system used, the volume of the liquid temporary storage tank was 5m 3 ; The volume of the gas storage tank is also 5m 3 The wellbore, wellhead, pipeline and two tanks in the system are designed as pressure-bearing equipment with a maximum pressure resistance of 3MPa. The submersible electric pump was tested using the test method proposed in this invention. First, the rated displacement was 30m 3 / d, the gas was injected and mixed transport test was carried out. A total of 3 groups of tests were carried out, with the gas mixing ratios of 30%, 70% and 100% respectively, and each group of tests lasted for 72 hours. Then the liquid displacement was reduced to 20m 3 / d and 10m 3 / d, and the gas input was reduced accordingly. Each set of test processes was tested continuously for 8 hours. The test method proposed in this invention successfully completed the above-mentioned mixed transmission test, evaluated the designed gas-liquid mixed transmission submersible electric pump, and provided reliable assurance for the improvement and promotion of equipment application.

[0036] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A test system specifically for testing gas-liquid mixed transmission submersible electric pumps in oil fields, characterized by: The invention comprises a simulation test wellbore (10) filled with crude oil simulation liquid (6) and having a sealed wellhead (31); a downhole device to be tested is placed in the simulation test wellbore (10) and completely immersed in the crude oil simulation liquid (6); the downhole device to be tested comprises a submersible motor (1), a motor protector (2), an oil-gas separator (3), and a gas-liquid mixed transmission type submersible pump (4); and further comprises a transformer (9) and a control cabinet (8) connected thereto; the control cabinet (8) is connected to the downhole device to be tested via a submersible cable (5) to adjust the power supply for the downhole device to be tested; the downhole device to be tested is connected to a liquid temporary storage tank (11) via an oil pipe (7); a throttle valve (26) is provided on the oil pipe (7); the liquid temporary storage tank (11) is connected to the liquid temporary storage tank (11) via a pipeline. a is connected to the simulation test wellbore (10), and an uphole liquid delivery pump (12) is provided on the pipeline a for circulating the liquid in the liquid temporary storage tank (11) into the simulation test wellbore (10); it also includes a gas temporary storage tank (14) filled with non-condensable gas, the gas temporary storage tank (14) is connected to the bottom of the simulation test wellbore (10) through a gas delivery pipe (17) for simulating downhole natural gas, and a compressor (15) and a regulating valve (27) are provided on the gas delivery pipe (17); the top of the liquid temporary storage tank (11), the top of the gas temporary storage tank (14), and the top of the sealed wellhead (31) are all equipped with a pressure gauge (24) and a safety valve (23); it also includes a variety of sensors and meters for monitoring equipment and pipeline parameters.

2. The test system for testing gas-liquid mixed transmission submersible electric pumps in oil fields according to claim 1, characterized in that: The invention also comprises at least one group of gas cylinders (18) connected to the gas temporary storage tank (14) through a pipeline b, for replenishing gas into the gas temporary storage tank (14), and another throttle valve (26) is provided on the pipeline b.

3. The test system for testing gas-liquid mixed transmission submersible electric pumps in oil fields according to claim 2, characterized in that: The multiple sensors and meters specifically include: a liquid flow meter (13) installed on the pipeline a for measuring the liquid input flow, a gas flow meter (16) installed on the gas transmission pipe (17) for measuring the gas input flow, a gas-liquid two-phase flow meter (19) installed on the oil pipe (7) for measuring the crude oil simulation liquid output flow, a current sensor (21) installed on the submersible cable (5) for measuring the three-phase current fluctuation value of the submersible motor (1), and a vibration sensor (22) connected to the gas-liquid mixed transmission type submersible pump (4) for measuring its vibration.

4. The test system for testing gas-liquid mixed transmission submersible electric pumps in oil fields according to claim 2, characterized in that: A separation element (30) for gas-liquid separation is provided in the liquid temporary storage tank (11), and a vent valve (25) is provided on the top of the liquid temporary storage tank (11).

5. The test system for testing gas-liquid mixed transmission submersible electric pumps in oil fields according to claim 3 is characterized in that: A sampler (20) is also installed on the oil pipe (7) for sampling the discharge of fluid.

6. The test system for testing a gas-liquid mixed transmission submersible electric pump in an oil field according to any one of claims 2 to 5, characterized in that: The sealed wellhead (31), the simulated test wellbore (10), the liquid temporary storage tank (11), the gas temporary storage tank (14), the gas cylinder (18) and the connecting pipelines are all pressure-bearing components, and the pressure resistance design value is 1-5 MPa.

7. A test method specifically for testing gas-liquid mixed transmission submersible electric pumps in oil fields, characterized by the following steps: include: The downhole equipment to be tested is placed in a simulated test wellbore (10), and the submersible motor (1) is connected to the transformer (9) and the control cabinet (8) via a submersible cable (5), and reliable insulation and sealing are performed; Start the uphole liquid delivery pump (12) and inject the crude oil simulation liquid (6) in the liquid temporary storage tank (11) into the simulated test wellbore (10) until the downhole equipment to be tested is completely immersed and a sufficient submergence and a stable liquid level are left; Power is supplied to the downhole equipment to be tested to start operation. During operation, the opening of the throttle valve (26) on the oil pipe (7) is adjusted to simulate the pump head; the submersible motor (1) is adjusted to simulate the pump output; Synchronously adjust the rotation speed of the on-hole liquid delivery pump (12) until the output flow rate of the crude oil simulation liquid is substantially equal to the liquid flow rate of the crude oil simulation liquid (6) injected from the liquid temporary storage tank (11) into the simulation test wellbore (10). At this time, the liquid delivery process of the gas-liquid mixed delivery submersible pump (4) reaches a steady state, and circulates in this state for a period of time to stabilize the system. Start the compressor (15) and inject the gas in the gas temporary storage tank (14) into the bottom of the well through the gas delivery pipe (17). The flow rate is controlled by the regulating valve (27). After the gas flow rate reaches the predetermined design flow rate, the operation is kept stable. At this time, the downhole equipment to be tested in the simulated test wellbore (10) is in a gas-liquid mixed transmission operation state, and the gas-liquid two-phase flow delivered to the ground by the gas-liquid mixed transmission submersible pump (4) is transported back to the liquid temporary storage tank (11), and after being separated by the separation element (30) in the liquid temporary storage tank (11), the gas is released into the atmosphere through the vent valve (25) on the tank top, and the liquid continues to circulate to the simulated test wellbore (10) for use.

8. The test method for testing a gas-liquid mixed transmission type submersible electric pump in an oil field according to claim 7, characterized in that: A portion of the fluid is periodically released through a sampler (20) installed on the oil pipe (7) and discharged into a transparent container with a volume scale and a weighing function to analyze the actual gas-liquid ratio in the gas-liquid two-phase flow and the separation state of the bubbles.

9. The test method for testing a gas-liquid mixed transmission submersible electric pump in an oil field according to claim 8, characterized in that: The three-phase current fluctuation value of the submersible motor (1) is monitored by the current sensor (21), and the vibration of the gas-liquid mixed transmission type submersible pump (4) is measured by the vibration sensor (22). The control cabinet (8) receives the signals of the current sensor (21) and the vibration sensor (22) to monitor the current fluctuation or vibration value. If the value exceeds a preset value, the control cabinet (8) first automatically reduces the frequency to reduce the speed of the submersible motor (1). If the condition still cannot be improved, the control cabinet (8) stops and issues an alarm.

10. The test method for testing a gas-liquid mixed transmission type submersible electric pump in an oil field according to any one of claims 7 to 9, characterized in that: The operation test runs continuously for 24h-240h.

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