Research on Efficacy Analysis and Optimization Operation of Submersible Electric Pump System

The submersible electric pump system consists of three major parts of eight units: Downhole parts: including submersible motors, protectors, separators and multi-stage centrifugal pumps; intermediate parts: submersible cables, oil well tubing (including single-flow valves, leakage Oil valve, etc.) Ground section: including control panel, transformer.

Ground Power Supply - Transformer Control Screen -> Submersible Cable - Submersible Motor Submersible Pump - Pumping Workflow: Separator One - Multistage Centrifugal Pump - Single Flow Valve - One Drainage Valve - One Wellhead - Outlet Line 2.2 The efficiency of submersible electric pump system decomposition 2.2.1 System efficiency Definition Submersible electric pump system in the production and operation of all parts of the transmission energy loss, the system has the input power and output power difference, this difference is reflected in each The product efficiency of each unit and the product of cumulative operating efficiency is the overall system efficiency.

The electric pump system is embodied by the efficiency of the transformer, control panel, cables, motors, submersible pump separators, protectors and string components. Due to the one-way continuity of the power supply flow and the oil flow, the output power of one unit of the system can be used as the input power of the next unit. Set the system power to 7, then there are: efficiency, protector efficiency, separator efficiency, centrifugal efficiency and column efficiency; Pl, p2 for the transformer input power and output power, kW; p3, p4, p5, household 6 Control panel, cable, motor, and protector output power, kW; p7, p8 is the input power and output power of the centrifugal pump, kW; P9 is the effective power of the submersible pump system (that is, the output power of the system unit 2.3 System power analysis and parameter testing method can be seen from the above analysis, there are energy loss in each unit of the submersible electric pump system, that is, the power consumption value APi, in the numerical system output power P9 is equal to the submersible pump input power A With the difference of the cumulative power loss values ​​of various parts, that is from the above, it is known that the system efficiency of the electric oil extraction well depends only on the ratio of the loss power to the input power, that is, if the input power is constant, the power AP is lost. The efficiency of the submersible electric pump system is lower; on the contrary, the higher the system efficiency, we know that to improve the system efficiency of the well, we must strive to reduce the power loss of various parts of the system.

According to the composition of the submersible pump, the power loss of the submersible pump system can be divided into eight parts: transformer loss, control panel loss, cable loss AP3, motor loss AP4, protector loss Ap5, separator Loss Ape, Centrifugal Pump Loss Ap7, Column Loss Ap7. In the course of operation of the transformer, there is both a loss of thermal energy and a natural decline in the transmission energy of the coil transformer, ie copper losses and iron losses known in electrical engineering. From electrical engineering knowledge, we know that: using a standard watt-hour meter to measure the input power and output power of the transformer, p2, can be obtained as the power value of C - meter constant; K - voltage transformer ratio; t ——The time spent on n-turns, U has learned that the loss of the transformer is: =P1 The measurement results show that the efficiency of the oil platform 6kV is generally between 95% and 98%.

The loss of the control panel is mainly the heat loss of some components. In its main loop, control loop and measurement display part, there is heat loss in each element. When testing the entire power consumption, set the overall output power of the control panel to p3. Since the output power of the transformer is the output power P2 of the control panel, the loss of the control panel is: =P2-P3. When measuring, it can be measured by Joule's law. The method of output power to the cable (same method as the test cable) has little energy loss of the control panel, generally does not exceed lkw, and the efficiency is about 99%.

The depth of the submersible cable varies with the depth of the pump. Since the heat loss of the cable is related to the cross-sectional area and length of the cable, the cable loss is tested by indirect methods. Using a multimeter to measure the resistance, known by Joule's law, the cable loss is known from the following formula: But when the current and voltage are constant, the power loss of the cable is related to the cross-sectional area and length of the cable, and is calculated by the following formula: The output power of the control panel is The input power of the cable minus the loss of the cable is the output power of the cable;) 4, ie, the motor is a device that converts electrical energy and mechanical energy. In the process of energy conversion, there will inevitably be energy loss. These losses include stator, rotor copper loss, bearing friction loss and so on. Due to structural reasons, the motor and the protector cannot be separated and can only be measured together. The energy loss of the protector is mainly mechanical friction loss. For a certain type of protector, the loss is basically a certain value. So the loss is mainly motor. The calculation results show that the motor is a component with a large loss in the system and its loss is calculated as follows: +7 power loss of separator and centrifugal pump, kW"; Pi - output power of centrifugal pump, kW; calculation within it The formula is as follows: H——The actual effective lift of the multi-stage centrifugal pump, m. The method of calculating a cadaver suction// is as follows: The difference of p row is equal to the hydraulic head of the lifting well fluid above the hydrodynamic surface, numerically Equal to: The motor efficiency is: / 3 rows of a household dynamic surface height, m;- wellhead oil pressure, sleeve pressure, MPa. ~ 100%) PN (rated power) range, the rated load when the submersible pump efficiency Between 75% and 95%, in order to maximize the efficiency of the motor at rated load, the key is to select the pump type of the submersible pump in accordance with the technical requirements of the submersible pump.

The separation efficiency of the separator is an important parameter that reflects the working condition in the well. The efficiency of the separator can be directly measured by the pump efficiency tester, ie, 卩6+7 is measured. The power loss of the separator and the centrifugal pump is: The calculation method of the centrifugal pump output power P8 is as described above. The loss of separator and centrifugal pump consists of three parts: mechanical loss, volume loss and hydraulic loss. The mechanical loss is mainly caused by the friction loss that the separator and the centrifugal pump can not avoid during the rotation process. The volume loss is mainly caused by the loss of the oil and gas separator incompletely under-loaded pump efficiency, and the hydraulic loss is mainly the reactionary twist of the lifted liquid. Power caused by energy loss. The efficiency of separators and centrifugal pumps is generally around 95%.

2.3.2.6 Column loss The submersible electric pump is located below the tree to the submersible motor, the vertical distance is close to 1000 meters, and the absolute length is between 1 and 1800. It has a long resistance loss section for the crude oil output. The effective power is: - well fluid density, kg/m3; h pump output total pressure head, m; 3 submersible electric pump system efficiency test method to test the efficiency of submersible electric pump system, the following two factors need to be considered: Under conditions of production and can only measure the output power, dynamic surface depth, daily production volume, oil pressure and sleeve pressure, some components can not be tested for decomposition.

The test well decomposing test is different from the operating condition of the production well, and there is no actual production well dynamic characteristics and the contingent factors can be investigated.

In view of the above considerations, test can be divided into test wells and production wells and comprehensive calculation considerations. Due to the structural features of the submersible pump, the system is decomposed into six parts: transformer, control panel, cable, motor plus protector, separator and centrifugal pump and pipe string system. Test the energy loss of various parts in different mining conditions, and then comprehensively calculate the system efficiency.

According to the existing tools of the platform, in order to strengthen the operability of the test method, it is generally required to conduct tests based on the full use of existing tools. The test and measurement instruments for submersible pump systems are classified as shown in Table 1. Table 1 Tests Instrumentation Classification Instrument Instrument Name Quantity Model Accuracy Voltage Transformer Current Transformer Standard Meter Dual Channel Echo Meter Clamp Ammeter Pump Efficiency Tester Electronic Stopwatch In the test tool, the pump efficiency tester platform team has not been configured, but The efficiency test of the pump can be obtained by theoretical methods.

The effectiveness of the submersible pump system can be based on the above analysis of the power consumption of each unit, and the actual field test verification. Experience shows that the efficiency of the submersible electric pump system can be about 85%. Submersible motors and multiple centrifuges have the highest wear rate. The power loss of the submersible motor accounts for about 30% of the total loss. The power loss of the multi-stage centrifugal pump accounts for 50% of the total loss, and the highest one can reach about 70%, which has a great influence on the system efficiency of the submersible electric pump. In the wells being produced, the efficiency of the submersible electric pump system will also be affected by the crude oil well conditions and the nature of the crude oil well fluid. One of its characteristics is that the system efficiency changes greatly; second, the value is low, with an average of about 80%.

4 Efficient operation design of submersible electric pump system According to the analysis of the overall system efficiency, it is necessary to improve the overall operating efficiency of the submersible electric pump, and the main task is to carry out scientific and technological innovation and optimization tests on the components with large energy consumption. This means that the energy saving and consumption reduction of transformers, control panels, cables, and string systems should be reformed from the selection of supporting materials. For us, the optimization of the production parameter design between the matching of various components (such as the pump type and the transformer model) is an important task in human scientific management.

4.1 Serialization of submersible electric pump products and improvement of pump efficiency Pump type displacements currently developed have ranged from 20m3/d to 200m3/d and over 30 specifications. Applicable production level with production well temperature up to 150:. The pump's head specifications are complete, and the newly developed unit number can be arbitrarily adjusted, reducing the under-load loss of the electric pump and improving the system efficiency. At present, the pump displacements used in the Chengdao Oilfield are 45m3/d, 60m3/d, 80m3/d, 100m3/d, 150m3/d, 200m3/d, etc. The motor power used is 24.8kW, 31kW, 43kW, and 55kW. , 62kW and so on. Therefore, according to the actual production capacity of each well, we must select the appropriate pump type so that it can be used for normal production. This is an effective method for improving the operating efficiency of the submersible electric pump system.

4.2 The use of high-efficiency separators increases degassing efficiency.

After analyzing the power consumption of the front separator, it can be seen that the wells with too large gas volume cannot be smoothly discharged, resulting in air lock or cavitation, which will seriously reduce the pump efficiency and cause a significant negative impact on the system efficiency. Therefore, the science of separators Choice has important significance.

The HS-1 separator is recommended here. The structure is characterized by a two-stage structure and multiple separations. The separation efficiency is improved, the effect of gas on the electric pump is significantly reduced, and the synergistic effect is obvious.

4.3 Application of Adjustable Nozzle to Reduce Pressure Loss Under normal circumstances, the entire system is operated in an efficient area by changing the diameter of the nozzle tip at the wellhead. The adjustable nozzle can be arbitrarily adjusted between 6 ~ 28mm, and it also has the function of low-pressure venting gas. It can set the gas under the condition that the sleeve pressure is lower than the oil pressure, thus increasing the range of the oil well's adjustment parameters, and the pump and the motor. The influence of the negative pressure of the separator, the separator and the column is obviously reduced, and the smooth operation of the pump under the rated or good load can be effectively maintained, which is a powerful measure for improving the system efficiency.

4.4 Finding the best operating point of the electric pump well and optimizing the parameter operation Optimizing the system efficiency of the submersible electric pump by using the best industrial and mining point of the submersible electric pump is an aspect of deep designing and managing the oil well, and it is also an energy-saving and energy-saving effect. Important task.

According to the principle of oil recovery engineering, the working point of the submersible electric pump is studied. Three factors should be considered comprehensively: pump characteristics, string characteristics, and seepage characteristics of the oil layer. The simple method is to draw these three curves on a graph, reflecting the equilibrium state of the three when the submersible pump is working stably, that is, the best operating point, and it is also the selection point of the oil well tuning. Such as.

(A, C, and Li a certain operating point: 0a, 9c,.: corresponding to the output of A, C, A1 working conditions; good corpse m: corresponds to A working condition point bottom hole flow pressure and lift lifting head />wfC, ugly DC: Corresponding to C working condition point bottom flow pressure and pump lift dynamic pressure head; pump characteristic curve; pipeline characteristic curve; (: seepage curve) Assume that A is a certain stable working point, corresponding to The diameter of the nozzle and the amount of fluid produced by Condition A are seen in the above. The operating condition of the electric pump is determined by the characteristics of the pump, the characteristics of the pipeline, and the characteristics of the well. When one of the factors changes, it will lead to production. A series of parameters such as liquid volume, hydraulic pressure, and oil pressure change, and by using this feature, the most efficient operating point of the system can be found within the pump displacement range, that is, the nozzle is first adjusted to the maximum diameter from the smallest diameter. Calculate the system efficiency that corresponds to a stable operating point, then the operating point with maximum efficiency is the optimal operating point.