Submersible ethn. Composition of the ESP installation, purpose of nodes, parameters

The scope of application of ESPs is high-yield water-flooded, deep and inclined wells with a flow rate of 10 ¸ 1300 m3/day and a lifting height of 500 ¸ 2000 m. The overhaul period of the ESP is up to 320 days or more.

Installations of modular submersible centrifugal pumps of the UETsNM and UETsNMK types are designed for pumping out oil well products containing oil, water, gas and mechanical impurities. Installations of the UETsNM type have a standard design, and the UETsNMK type have a corrosion-resistant design.

The installation (Figure 24) consists of a submersible pumping unit, a cable line lowered into the well on tubing, and surface electrical equipment (transformer substation).

The submersible pumping unit includes a motor (an electric motor with hydraulic protection) and a pump, above which a check valve and drain valve are installed.

Depending on the maximum transverse dimension of the submersible unit, the installations are divided into three conditional groups - 5; 5A and 6:

· Group 5 units with a transverse dimension of 112 mm are used in wells with a casing string with an internal diameter of at least 121.7 mm;

· installations of group 5A with a transverse dimension of 124 mm - in wells with an internal diameter of at least 130 mm;

· installations of group 6 with a transverse dimension of 140.5 mm - in wells with an internal diameter of at least 148.3 mm.

Conditions of applicability of ESP for pumped media: liquid with a mechanical impurity content of no more than 0.5 g/l, free gas at the pump intake no more than 25%; hydrogen sulfide no more than 1.25 g/l; water no more than 99%; pH value of formation water is within 6 ¸ 8.5. The temperature in the area where the electric motor is located is no more than + 90 ˚С (special heat-resistant version up to + 140 ˚С).

An example installation code - UETsNMK5-125-1300 means: UETsNMK - installation of an electric centrifugal pump of modular and corrosion-resistant design; 5 - pump group; 125 - supply, m3/day; 1300 - developed pressure, m of water. Art.

Figure 24 - Installation of a submersible centrifugal pump

1 - wellhead equipment; 2 - remote connection point; 3 - transformer complex substation; 4 - drain valve; 5 - Check Valve; 6 - module-head; 7 - cable; 8 - module-section; 9 - gas separator pump module; 10 - source module; 11 - protector; 12 - electric motor; 13 - thermomanometric system.

Figure 24 shows a diagram of the installation of submersible centrifugal pumps in a modular design, representing a new generation of equipment of this type, which allows you to individually select the optimal layout of the installation for wells in accordance with their parameters from a small number of interchangeable modules. Installations (in Figure 24 - diagram of NPO Borets ", Moscow) provide optimal selection of the pump to the well, which is achieved by the presence of a large number of pressures for each supply. The unit pressure pitch ranges from 50 ¸ 100 to 200 ¸ 250 m, depending on the supply in the intervals specified in Table 6 of the basic data of the units.

Commercially produced ESPs have a length from 15.5 to 39.2 m and a weight from 626 to 2541 kg, depending on the number of modules (sections) and their parameters.

In modern installations, from 2 to 4 module sections can be included. A package of steps is inserted into the section body, which consists of impellers and guide vanes assembled on a shaft. The number of stages ranges from 152 to 393. The input module represents the base of the pump with intake holes and a filter mesh through which liquid from the well enters the pump. At the top of the pump there is a fishing head with a check valve, to which the tubing is attached.

Table 6

Name of installations	Minimum (internal) diameter of the exploitation column, mm	Transverse installation dimensions, mm	Supply m3/day		Engine power, kW	Gas separator type
UETsNMK5-80
UETsNMK5-125
UETsNM5A-160
UETsNM5A-250
UETsNMK5-250
UETsNM5A-400
UETsNMK5A-400
	144.3 or 148.3	137 or 140.5
UETsNM6-1000

The pump (ETsNM) is a submersible centrifugal modular multistage vertical design.

Pumps are also divided into three conditional groups - 5; 5A and 6. Case diameters of group 5 ¸ 92 mm, group 5A - 103 mm, group 6 - 114 mm.

The pump section module (Figure 25) consists of a housing 1 , shaft 2 , stage packages (impellers - 3 and guide vanes - 4 ), upper bearing 5 , lower bearing 6 , upper axial support 7 , heads 8 , grounds 9 , two ribs 10 (serve to protect the cable from mechanical damage) and rubber rings 11 , 12 , 13 .

The impellers move freely along the shaft in the axial direction and are limited in movement by the lower and upper guide vanes. The axial force from the impeller is transmitted to the lower textolite ring and then to the guide vane collar. Partial axial force is transferred to the shaft due to friction of the wheel on the shaft or sticking of the wheel to the shaft due to the deposition of salts in the gap or corrosion of metals. Torque is transmitted from the shaft to the wheels by a brass (L62) key that fits into the groove of the impeller. The key is located along the entire length of the wheel assembly and consists of segments 400 - 1000 mm long.

Figure 25 - Module-section pump

1 - frame; 2 - shaft; 3 - impeller; 4 - guide apparatus; 5 - upper bearing; 6 - lower bearing; 7 - upper axial support; 8 - head; 9 - base; 10 - edge; 11 , 12 , 13 - rubber rings.

The guide vanes are articulated with each other along their peripheral parts; in the lower part of the housing they all rest on the lower bearing 6 (Figure 25) and base 9 , and from above through the upper bearing housing are clamped in the housing.

The impellers and guide vanes of standard pumps are made of modified gray cast iron and radiation-modified polyamide; corrosion-resistant pumps are made of modified cast iron TsN16D71KhSh of the “niresist” type.

The shafts of section modules and input modules for pumps of standard design are made of combined corrosion-resistant high-strength steel OZH14N7V and are marked “NZh” at the end; for pumps with increased corrosion resistance - from calibrated rods made of N65D29YUT-ISH-K-Monel alloy and are marked at the ends "M".

The shafts of the module sections of all groups of pumps, which have the same body lengths of 3, 4 and 5 m, are unified.

The connection of the shafts of the section modules with each other, the section module with the input module shaft (or gas separator shaft), and the input module shaft with the engine hydraulic protection shaft is carried out using splined couplings.

The connection between the modules and the input module to the motor is flanged. The connections (except for the connection of the input module to the engine and the input module to the gas separator) are sealed with rubber rings.

To pump out formation fluid containing more than 25% (up to 55%) by volume of free gas at the pump input module grid, a pump-gas separator module is connected to the pump (Figure 26).

Figure 26 - Gas separator

1 - head; 2 - adapter; 3 - separator; 4 - frame; 5 - shaft; 6 - grate; 7 - guide vane; 8 - Working wheel; 9 - auger; 10 - bearing; 11 - base.

The gas separator is installed between the input module and the section module. The most effective gas separators are of the centrifugal type, in which the phases are separated in a field of centrifugal forces. In this case, the liquid is concentrated in the peripheral part, and the gas is concentrated in the central part of the gas separator and is released into the annulus. Gas separators of the MNG series have a maximum flow of 250 ¸ 500 m3/day, a separation coefficient of 90%, and a weight of 26 to 42 kg.

The engine of a submersible pumping unit consists of an electric motor and hydraulic protection. Electric motors (Figure 27) are submersible three-phase short-circuited two-pole oil-filled motors of the usual and corrosion-resistant design of the unified PEDU series and in the usual version of the PED modernization series L. Hydrostatic pressure in the operating area is no more than 20 MPa. Rated power from 16 to 360 kW, rated voltage 530 ¸ 2300 V, rated current 26 ¸ 122.5 A.

Figure 27 - Electric motor of the PEDU series

1 - coupling; 2 - lid; 3 - head; 4 - heel; 5 - thrust bearing; 6 - cable entry cover; 7 - cork; 8 - cable entry block; 9 - rotor; 10 - stator; 11 - filter; 12 - base.

Hydraulic protection (Figure 28) of SEM motors is designed to prevent formation fluid from penetrating into the internal cavity of the electric motor, compensating for changes in the volume of oil in the internal cavity from the temperature of the electric motor and transmitting torque from the electric motor shaft to the pump shaft.

Figure 28 - Water protection

A - open type; b- closed type

A- upper chamber; B- down Cam; 1 - head; 2 - mechanical seal; 3 - upper nipple; 4 - frame; 5 - middle nipple; 6 - shaft; 7 - lower nipple; 8 - base; 9 - connecting tube; 10 - diaphragm.

The hydraulic protection consists of either one protector or a protector and a compensator. There may be three options for hydraulic protection.

The first consists of protectors P92, PK92 and P114 (open type) from two chambers. The upper chamber is filled with a heavy barrier liquid (density up to 2 g/cm3, immiscible with formation fluid and oil), the lower chamber is filled with MA-PED oil, the same as the cavity of the electric motor. The cameras are connected by a tube. Changes in the volume of liquid dielectric in the engine are compensated by transferring the barrier liquid in the hydraulic protection from one chamber to another.

The second consists of protectors P92D, PK92D and P114D (closed type), which use rubber diaphragms; their elasticity compensates for changes in the volume of liquid dielectric in the engine.

The third - hydraulic protection 1G51M and 1G62 consists of a protector located above the electric motor and a compensator attached to the lower part of the electric motor. The mechanical seal system provides protection against formation fluid ingress along the shaft into the electric motor. Transmitted power of hydraulic protection is 125 ¸ 250 kW, weight 53 ¸ 59 kg.

The thermomanometric system TMS-3 is designed for automatic control of the operation of a submersible centrifugal pump and its protection from abnormal operating conditions (at reduced pressure at the pump intake and elevated temperature of the submersible electric motor) during well operation. There are underground and above ground parts. Controlled pressure range from 0 to 20 MPa. Operating temperature range from 25 to 105 ˚С.

Total weight 10.2 kg (see Figure 24).

The cable line is a cable assembly wound on a cable drum.

The cable assembly consists of a main cable - a round PKBK (cable, polyethylene insulation, armored, round) or a flat cable - KPBP (Figure 29), connected to it by a flat cable with a cable entry coupling (extension cord with a coupling).

Figure 29 - Cables

A- round; b- flat; 1 - lived; 2 - insulation; 3 - shell; 4 - pillow; 5 - armor.

The cable consists of three cores, each of which has an insulation layer and a sheath; cushions made of rubberized fabric and armor. Three insulated cores of a round cable are twisted along a helical line, and the cores of a flat cable are laid parallel in one row.

The KFSB cable with fluoroplastic insulation is designed for operation at ambient temperatures up to + 160 ˚С.

The cable assembly has a unified cable entry coupling K38 (K46) of the round type. The insulated conductors of the flat cable are hermetically sealed in the metal housing of the coupling using a rubber seal.

Plug lugs are attached to the conductive conductors.

The round cable has a diameter from 25 to 44 mm. Flat cable sizes from 10.1x25.7 to 19.7x52.3 mm. Nominal construction length 850, 1000 ¸ 1800 m.

Complete devices of the ShGS5805 type provide switching on and off of submersible motors, remote control from the control center and program control, operation in manual and automatic modes, shutdown in case of overload and deviation of the supply voltage above 10% or below 15% of the nominal, current and voltage control, as well as an external light alarm for emergency shutdown (including with a built-in thermometric system).

The integrated transformer substation for submersible pumps - KTPPN is designed to supply electricity and protect electric motors of submersible pumps from single wells with a capacity of 16 ¸ 125 kW inclusive. Rated high voltage 6 or 10 kV, medium voltage regulation limits from 1208 to 444 V (transformer TMPN100) and from 2406 to 1652 V (TMPN160). Weight with transformer 2705 kg.

The complete transformer substation KTPPNKS is designed for power supply, control and protection of four centrifugal electric pumps with 16 ¸ 125 kW electric motors for oil production in well pads, powering up to four electric motors of pumping machines and mobile pantographs when performing repair work. KTPPNKS is designed for use in the conditions of the Far North and Western Siberia.

The installation package includes: pump, cable assembly, motor, transformer, complete transformer substation, complete device, gas separator and tool kit.

More than 60 percent of oil production wells require some form of artificial lift technology to produce initially identified recoverable reserves. Of the approximately 832,000 artificial lift wells in the world, approximately 14 percent have been or are being produced using ESP.

Mechanized production methods are an integral part of well operation, especially in fields at a late stage of development, where productive formations do not have sufficient pressure to lift oil to the wellhead. As gas and oil well flow rates continue to decline and water flow rates increase, particularly in water-pressurized formations, an oil producer may begin to use waterflooding, a method of enhancing oil recovery in which water is injected into the formation through a water injection well to move hydrocarbons to other wells.

At the same time, over time, the oil flow rate of the well will continue to decrease, and the water flow rate will increase. As a result, the pumping time, for example, for a pumping machine increases until the pump runs twenty-four hours a day. At this time, the most practical method of increasing production is to install a pump with a higher capacity.

One viable option, especially for large volume flooding operations, is an electrically driven submersible pump. ESP systems may be the best option for high-yield wells where production levels have fallen and there is a need to increase it. This task is relevant for many fields in Russian Federation and CIS countries. Old gas lift systems in conditions of severe watering can operate at lower pressures and provide a more complete selection of recoverable oil reserves if funds are spent on converting these wells to ESPs.

Of all artificial lift systems electric centrifugal pumps (ECP) provide the greatest return on the deepest wells, but at the same time their use requires more frequent repairs and a corresponding increase in costs. In addition, ESPs provide superior performance in gas and water saturated environments. Gas and water are naturally present in crude oil in large quantities. To be able to pump oil at the wellhead, it is necessary to separate gas and water from it. Their high content can cause gas locks in the pump mechanism, which will lead to a significant decrease in productivity and will require removing the entire tubing string from the well and refilling it.

Electric centrifugal pump technology

In most oil fields, during the production stage, downhole pumps that are electrically driven are used to pump oil at the wellhead. The pump typically includes multiple centrifugal pump sections in series, which can be configured to meet specific wellbore parameters for a specific application. Electric centrifugal pumps (ECPs) are a common method of artificial lift, providing a wide range of sizes and capacities. Electric centrifugal pumps are typically used in old fields with high water content (high water-to-oil ratio).

ESP pumps provide economical production by enhancing oil recovery in these low-producing brownfields. Completions equipped with ESP are an alternative means of mechanized operation of wells that have low bottomhole pressures. Well completions equipped with an ESP are the most effective way to operate high-yield wells. When using large-sized ESPs, flow rates of up to 90,000 barrels (14,500 m3) of liquid per day were obtained.

ESP components

An ESP system consists of several components that rotate centrifugal pumps connected in series to increase the pressure of the well fluid and lift it to the wellhead. Power to rotate the pump is provided by a high-voltage (3 to 5 kV) AC power source that drives a special motor capable of operating at high temperatures up to 300 °F (150 °C) and high pressures up to 5000 psi (34 MPa) in wells up to 12,000 feet (3.7 km) deep with power inputs up to 1,000 horsepower (750 kW). An ESP uses a centrifugal pump that is connected to an electric motor and operates when immersed in the well fluid. A hermetically sealed electric motor rotates a series of impellers. Each impeller in the series supplies fluid through an outlet to the inlet of the impeller located above it.

On a typical 4 inch ESP, each impeller produces approximately 9 psi (60 kPa) of pressure gain. For example, a typical 10-section pump produces about 90 psi (600 kPa) pressure at the outlet (i.e. 10 wheels x 9 psi). The lift and performance of the pump depend on the diameter of the impeller and the width of the impeller blade. Pump pressure is a function of the number of impellers. As an example, a 7-section 1/2 horsepower pump can pump a large volume of water at low pressure, while a 14-section 1/2 horsepower pump will pump a smaller volume at a higher pressure. As with all centrifugal pumps, increasing well depth or outlet pressure results in decreased performance.

In ESP systems, the electric motor is located at the bottom of the arrangement and the pump at the top. An electrical cable is attached to the outer surface of the tubing and the assembly is lowered into the well so that the pump and electric motor are below the fluid level. A mechanical seal system and equalizer/safety seal (equivalent names) are used to prevent fluid from entering the motor and eliminate the risk of short circuits. The pump can be connected either to a pipe, to a flexible hose, or lowered along guide rails or wires in such a way that the pump sits on a flange coupling with a foot and at the same time a connection to the compressor pipes is ensured. When the electric motor rotates, the rotation is transmitted to the impeller in a battery of sequential centrifugal pumps. The more sections the pump has, the higher the liquid lift will be.

The electric motor is selected taking into account the needs of the pump. The pump is designed to pump out a certain volume of liquid. The shaft can be made of Monel metal, and the sections can be made of corrosion- and wear-resistant material. The pump has a rotary-centrifugal action. A guard assembly is attached to the top of the pump to isolate the motor and provide central shaft movement to drive the pump.

The cable runs from the top of the motor, to the side of the pump/seal, and is attached to the outside surface of each tubing along the entire length of the lift string from the motor to the wellhead and then to the electrical distribution box. The cable consists of three cores of protected and insulated continuous wire. Due to limited clearance around the pump/seal, a flat cable is used between the motor and the tubing above the pump. At this point it is spliced ​​with a less expensive round cable that extends to the mouth. The cable may have a metal sheath to protect it from damage.

The design of ESP systems requires a comprehensive and careful analysis in order to simultaneously solve a number of specific problems of their application. Design requires information on well inflow (flow curve (FC) or well productivity curve (CPC)), data on well fluids (oil flow rate, oil-water factor, gas-liquid ratio), data on pipes (depths and sizes of tubing and casing pipes) , temperature (at the bottom and at the wellhead), and pressure at the wellhead. Proper design and selection of equipment also requires information on solids, scale, asphaltenes, corrosive liquids, corrosive gases, etc.

Wellhead equipment requires installation power transformer and control panel, as well as air-cooled electrical distribution box. If the use of a variable speed drive (VSD) is required, then an additional step-up transformer is required in the circuit before the cable enters the wellhead. The tubing head is designed to hold the tubing string and insulate the electrical cable. This insulator is typically capable of withstanding a minimum of 3,000 psi. The control panel is usually equipped with an ammeter, fuses, lightning protection and a shutdown system. It has other devices such as high and low current switch and alarm. It allows you to operate the well continuously, intermittently, or completely stop production.

It provides protection against voltage spikes or imbalances that may occur in the power supply. Transformers are usually located at the edge of the cluster base. The incoming electrical voltage is transformed into the voltage required to operate the motor at the intended load and to compensate for cable losses. Higher voltage (lower current) reduces downhole cable losses, but other factors must be considered (Field Pump Reference Manual, 2006). ESPs sharply lose performance when a significant percentage of gas enters the pump.

The threshold level for the onset of a gas problem is generally taken to be 10% of the gas volume fraction at the pump inlet at the pump inlet pressure. Due to the fact that the pumps have a high rotation speed of up to 4000 rpm (67 Hz) and small clearances, they are not resistant to solid phases such as sand. ESPs for oil wells are available for casing diameters from 4 1/2 to 9 5/8 inches. Larger diameter casing pumps are available, but they are used primarily in water wells. For a given casing size, typically more optimal choice is equipment with a large diameter. Larger diameter equipment is shorter, both the motor and pumps are more efficient, and motors are easier to cool. They create quiet, compact wellhead equipment.

Advantages of ESP

Due to the minimal equipment requirements at the wellhead, ESPs may be favored for applications on sites with limited work space, such as offshore installations, where lifting costs are not a limiting factor. They are also used in fields where gas is not available for gas lift systems. ESPs are one of the most high-volume methods of mechanized operation. ESPs have an advantage over other high-volume methods because they can create higher reservoir drawdown and increase reservoir productivity where gas and sand interference problems can be addressed. The diameter of the casing is also not important to ensure the ability to pump such large volumes.

As waterflood volumes increase, it has become common practice to pump several thousand barrels of fluid per day to improve reservoir displacement efficiency. This system can be easily automated and can pump periodically or continuously, but continuous pumping is preferred to increase service life. For shallow wells, capital costs are relatively low.

Disadvantages of ESP

There are several disadvantages of ESPs. The main problem is the limited service life. The pump itself is a high speed centrifugal type which can be damaged by abrasives, solids or debris. The formation of scale or mineral deposits may interfere with the operation of the electric centrifugal pump. The economic efficiency of ESPs largely depends on the cost of electricity. This is especially critical in remote regions. The system does not have wide operational flexibility. All the main components are located near the wellbore, so when a problem arises or a component needs to be replaced, the entire system has to be removed.

If present high percent gas, measures are taken to separate it and return it back to the casing before it enters the pump. Drawing in large volumes of free gas can cause erratic operation and lead to mechanical wear and possible overheating. In offshore installations where regulations require the use of a packer, all gas is pumped out with liquid. In these special conditions, special pumps are used in which it is possible to create a primary pressure at the pump intake.

Authors: James F. Lee, Kerr McGee Professor of Petroleum Engineering, School of Geology and Petroleum Technology, University of Oklahoma, Norman, Oklahoma;
and Saeed Mokhtab, Natural Gas Research Advisor, Department of Petroleum Chemistry and Engineering, University of Wyoming, Laramie, Wyoming.

Purpose and technical data of ESP.

Submersible centrifugal pump installations are designed for pumping out reservoir fluid containing oil, water and gas, and mechanical impurities from oil wells, including inclined ones. Depending on the number of different components contained in the pumped-out liquid, the pumps of the installations have a standard design and a version with increased corrosion and wear resistance. When operating an ESP, where the concentration of solids in the pumped-out liquid exceeds the permissible 0.1 gram/liter, the pumps become clogged and the working units wear out intensively. As a result, vibration increases, water enters the motor through the mechanical seals, and the engine overheats, which leads to failure of the ESP.

Symbol of installations:

ESP K 5-180-1200, U 2 ESP I 6-350-1100,

Where U - installation, 2 - second modification, E - driven by a submersible electric motor, C - centrifugal, N - pump, K - increased corrosion resistance, I - increased wear resistance, M - modular design, 6 - groups of pumps, 180, 350 - supply m/day, 1200, 1100 – pressure, m.w.st.

Depending on the diameter of the production string and the maximum transverse dimension of the submersible unit, ESPs of various groups are used - 5.5, and 6. Installation of group 5 with a transverse diameter of at least 121.7 mm. Group 5a installations with a transverse dimension of 124 mm - in wells with an internal diameter of at least 148.3 mm. Pumps are also divided into three conditional groups - 5.5 a, 6. The diameters of the housings of group 5 are 92 mm, group 5 a - 103 mm, group 6 - 114 mm. Technical characteristics of pumps of the ETsNM and ETsNMK types are given in Appendix 1.

Composition and completeness of the ESP

The ESP installation consists of a submersible pumping unit (an electric motor with hydraulic protection and a pump), a cable line (a round flat cable with a cable entry coupling), a tubing string, wellhead equipment and surface electrical equipment: a transformer and a control station (complete device) (see Figure 1.1 .). The transformer substation converts the field network voltage to a sub-optimal value at the electric motor terminals, taking into account voltage losses in the cable. The control station provides control of the operation of pumping units and its protection under optimal conditions.

A submersible pumping unit, consisting of a pump and an electric motor with hydraulic protection and a compensator, is lowered into the well along the tubing. The cable line provides power supply to the electric motor. The cable is attached to the tubing with metal wheels. Along the length of the pump and protector, the cable is flat, attached to them with metal wheels and protected from damage by casings and clamps. Check and drain valves are installed above the pump sections. The pump pumps out fluid from the well and delivers it to the surface through the tubing string (see Figure 1.2.)

The wellhead equipment provides suspension of the tubing string with an electric pump and cable on the casing flange, sealing of pipes and cables, as well as drainage of the produced fluid into the outlet pipeline.

A submersible, centrifugal, sectional, multistage pump does not differ in operating principle from conventional centrifugal pumps.

Its difference is that it is sectional, multi-stage, with a small diameter of working stages - impellers and guide vanes. Submersible pumps produced for the oil industry contain from 1300 to 415 stages.

The pump sections, connected by flange connections, are made of a metal casing. Made from steel pipe 5500 mm long. The length of the pump is determined by the number of operating stages, the number of which, in turn, is determined by the main parameters of the pump. - feed and pressure. The flow and pressure of the stages depend on cross section and the design of the flow part (blades), as well as on the rotation speed. A package of stages is inserted into the body of the pump sections, which is an assembly of impellers and guide vanes on a shaft.

The impellers are mounted on the shaft on a feather key along a running fit and can move in the axial direction. The guide vanes are secured against rotation in the nipple body, located in the upper part of the pump. From below, a pump base with receiving holes and a filter is screwed into the housing, through which liquid from the well flows to the first stage of the pump.

The upper end of the pump shaft rotates in the oil seal bearings and ends with a special heel that takes the load on the shaft and its weight through a spring ring. Radial forces in the pump are absorbed by plain bearings installed at the base of the nipple and on the pump shaft.

At the top of the pump there is a fishing head in which a check valve is installed and to which the tubing is attached.

Submersible electric motor, three-phase, asynchronous, oil-filled with a squirrel-cage rotor in a conventional version and a corrosion-resistant version PEDU (TU 16-652-029-86). Climatic modification - B, placement category - 5 according to GOST 15150 - 69. At the base of the electric motor there is a valve for pumping oil and draining it, as well as a filter for cleaning the oil from mechanical impurities.

The hydraulic protection of the motor motor consists of a protector and a compensator. It is designed to protect the internal cavity of the electric motor from formation fluid, as well as to compensate for temperature changes in oil volumes and its consumption. (See Figure 1.3.)

The protector is two-chamber, with a rubber diaphragm and mechanical shaft seals, and a compensator with a rubber diaphragm.

Three-core cable with polyethylene insulation, armored. Cable line, i.e. a cable wound on a drum, to the base of which an extension is attached - a flat cable with a cable entry coupling. Each cable core has an insulation layer and a sheath, cushions made of rubberized fabric and armor. Three insulated cores of a flat cable are laid parallel in a row, and a round cable is twisted along a helical line. The cable assembly has a unified cable entry coupling K 38, K 46 of the round type. In a metal casing, the couplings are hermetically sealed using a rubber seal, and tips are attached to the conductive conductors.

The design of ESP installations, ESPNM with a pump having a shaft and stages made of corrosion-resistant materials, and ESP with a pump having plastic impellers and rubber-metal bearings is similar to the design of ESP installations.

When the gas factor is high, pump modules are used - gas separators, designed to reduce the volumetric content of free gas at the pump intake. Gas separators correspond to product group 5, type 1 (repairable) according to RD 50-650-87, climatic version - B, placement category - 5 according to GOST 15150-69.

Modules can be supplied in two versions:

Gas separators: 1 MNG 5, 1 MNG5a, 1 MNG6 – standard design;

Gas separators 1 MNGK5, MNG5a - increased corrosion resistance.

Pumping modules are installed between the input module and the submersible pump section module.

The submersible pump, electric motor, and hydraulic protection are connected to each other by flanges and studs. The pump, motor and protector shafts have splines at the ends and are connected by splined couplings.

Accessories for lifts and equipment for ESP installations are given in Appendix 2.

Technical characteristics of the motor

The drive of submersible centrifugal pumps is a special oil-filled submersible asynchronous three-phase alternating current electric motor with a vertical squirrel-cage rotor of the PED type. Electric motors have housing diameters of 103, 117, 123, 130, 138 mm. Since the diameter of the electric motor is limited, at high powers the motor is longer, and in some cases it is made sectional. Since the electric motor operates immersed in liquid and often under high hydrostatic pressure, the main condition for reliable operation is its tightness (see Figure 1.3).

The PED is filled with a special low-viscosity, high dielectric strength oil, which serves both for cooling and lubrication of parts.

A submersible electric motor consists of a stator, rotor, head, and base. The stator housing is made of steel pipe, the ends of which are threaded for connecting the head and base of the motor. The stator magnetic circuit is assembled from active and non-magnetic laminated sheets having grooves in which the windings are located. The stator winding can be single-layer, continuous, coil or double-layer, rod, loop. The winding phases are connected.

The active part of the magnetic circuit, together with the winding, creates a rotating magnetic field in electric motors, and the non-magnetic part serves as supports for the intermediate rotor bearings. Lead ends made of stranded copper wire with insulation having high electrical and mechanical strength are soldered to the ends of the stator winding. Plug sleeves are soldered to the ends, into which the cable lugs fit. The output ends of the winding are connected to the cable through a special plug block (coupler) of the cable entry. The motor current lead can also be a knife type. The motor rotor is squirrel-cage, multi-section. It consists of a shaft, cores (rotor packages), radial supports (sliding bearings). The rotor shaft is made of hollow calibrated steel, the cores are made of sheet electrical steel. The cores are assembled onto the shaft, alternating with radial bearings, and are connected to the shaft with keys. Tighten the set of cores on the shaft axially with nuts or a turbine. The turbine serves for forced circulation of oil to equalize the engine temperature along the length of the stator. To ensure oil circulation, there are longitudinal grooves on the immersed surface of the magnetic circuit. The oil circulates through these grooves, a filter at the bottom of the engine where it is cleaned, and through a hole in the shaft. The engine head contains a heel and a bearing. The adapter at the bottom of the engine is used to accommodate the filter, bypass valve and valve for pumping oil into the engine. The sectional electric motor consists of upper and lower sections. Each section has the same main components. Technical characteristics of the SEM are given in Appendix 3.

Basic technical data of the cable

The supply of electricity to the electric motor of the submersible pump installation is carried out through a cable line consisting of a power cable and a cable entry coupling for coupling with the electric motor.

Depending on the purpose, the cable line may include:

Cable brands KPBK or KPPBPS - as the main cable.

Cable brand KPBP (flat)

The cable entry sleeve is round or flat.

The KPBK cable consists of single-wire or multi-wire copper cores, insulated in two layers of high-strength polyethylene and twisted together, as well as a cushion and armor.

Cables of the KPBP and KPPBPS brands in a common hose sheath consist of single-wire and multi-wire copper conductors, insulated with high-density polyethylene and laid in the same plane, as well as a common hose sheath, cushion and armor.

Cables of the KPPBPS brand with separately hosed conductors consist of single- and multi-wire copper conductors, insulated in two layers of high-density polyethylene and laid in the same plane.

The KPBK brand cable has:

Operating voltage V – 3300

The KPBP brand cable has:

Operating voltage, V - 2500

Allowable formation fluid pressure, MPa – 19.6

Permissible gas factor, m/t – 180

KPBK and KBPP brand cables have permissible ambient temperatures from 60 to 45 C for air, 90 C for formation fluid.

Cable line temperatures are given in Appendix 4.

1.2. Brief overview of domestic schemes and installations.

Submersible centrifugal pump installations are designed for pumping oil wells, including inclined ones, formation fluid containing oil and gas, and mechanical impurities.

The units are available in two types – modular and non-modular; three versions: normal, corrosion-resistant and increased wear resistance. The pumped medium of domestic pumps must have the following indicators:

· reservoir wildness – a mixture of oil, associated water and oil gas;

· maximum kinematic viscosity of formation fluid 1 mm/s;

· pH value of produced water pH 6.0-8.3;

· maximum content of obtained water 99%;

· free gas at intake up to 25%, for installations with modules - separators up to 55%;

· maximum temperature of extracted products up to 90C.

Depending on the transverse dimensions of the submersible centrifugal electric pumps, electric motors and cable lines used in the set of installations, the installations are conventionally divided into 2 groups 5 and 5 a. With casing diameters of 121.7 mm; 130 mm; 144.3 mm respectively.

The UEC installation consists of a submersible pumping unit, a cable assembly, ground electrical equipment - a transformer commutation substation. The pumping unit consists of a submersible centrifugal pump and a motor with hydraulic protection, and is lowered into the well on a tubing string. Submersible pump, three-phase, asynchronous, oil-filled with a rotor.

The hydraulic protection consists of a protector and a compensator. Three-core cable with polyethylene insulation, armored.

The submersible pump, electric motor and hydraulic protection are connected to each other by flanges and studs. The pump, motor and protector shafts have splines at the ends and are connected by splined couplings.

1.2.2. Submersible centrifugal pump.

The operating principle of a submersible centrifugal pump is no different from conventional centrifugal pumps used for pumping liquids. The difference is that it is multi-sectional with a small diameter of working stages - impellers and guide vanes. The impellers and guide vanes of conventional pumps are made of modified gray cast iron, corrosion-resistant pumps are made of niresist cast iron, and wear-resistant wheels are made of polyamide resins.

The pump consists of sections, the number of which depends on the main parameters of the pump - pressure, but not more than four. Section length up to 5500 meters. For modular pumps it consists of an input module, a module - section. Module - heads, check valves and drain valves. The connection of the modules to each other and the input module to the motor - flange connection (except for the input module, motor or separator) is sealed with rubber cuffs. The connection of the shafts of the module sections with each other, the module section with the input module shaft, and the input module shaft with the engine hydraulic protection shaft is carried out using splined couplings. The shafts of module sections of all groups of pumps with the same body lengths are unified in length.

The module section consists of a housing, a shaft, a package of stages (impellers and guide vanes), upper and lower bearings, an upper axial support, a head, a base, two ribs and rubber rings. The ribs are designed to protect the flat cable with coupling from mechanical damage.

The inlet module consists of a base with holes for the passage of formation fluid, bearing bushings and a grid, a shaft with protective bushings and a splined coupling designed to connect the module shaft with the hydraulic protection shaft.

The head module consists of a body, on one side of which there is an internal conical thread for connecting a check valve, on the other side there is a flange for connection to the section module, two ribs and a rubber ring.

There is a fishing head at the top of the pump.

The domestic industry produces pumps with a flow rate (m/day):

Modular – 50,80,125,200.160,250,400,500,320,800,1000.1250.

Non-modular – 40.80,130.160,100,200,250,360,350,500,700,1000.

The following heads (m) - 700, 800, 900, 1000, 1400, 1700, 1800, 950, 1250, 1050, 1600, 1100, 750, 1150, 1450, 1750, 1800, 1700, 1550, 130 0.

1.2.3. Submersible motors

Submersible electric motors consist of an electric motor and hydraulic protection.

Motors are three-phase, asynchronous, squirrel-cage, two-pole, submersible, unified series. SEMs in normal and corrosive versions, climatic version B, location category 5, operate from an alternating current network with a frequency of 50 Hz and are used as a drive for submersible centrifugal pumps.

The engines are designed to operate in formation fluid (a mixture of oil and produced water in any proportions) with temperatures up to 110 C containing:

· mechanical impurities no more than 0.5 g/l;

· free gas no more than 50%;

· hydrogen sulfide for normal, no more than 0.01 g/l, corrosion-resistant up to 1.25 g/l;

The hydraulic pressure in the engine operating area is no more than 20 MPa. Electric motors are filled with oil with a breakdown voltage of at least 30 kV. The maximum long-term permissible temperature of the stator winding of an electric motor (for a motor with a housing diameter of 103 mm) is 170 C, for other electric motors it is 160 C.

The engine consists of one or more electric motors (upper, middle and lower, power from 63 to 630 kW) and a protector. An electric motor consists of a stator, a rotor, a head with a current input, and a housing.

1.2.4. Hydraulic protection of the electric motor.

The hydraulic protection is designed to prevent formation fluid from penetrating into the internal cavity of the electric motor, compensating the volume of oil in the internal cavity from the temperature of the electric motor and transmitting torque from the electric motor shaft to the pump shaft. There are several options for water protection: P, PD, G.

Hydroprotection is available in standard and corrosion-resistant versions. The main type of hydraulic protection for the SED configuration is the open type hydraulic protection. Open type hydraulic protection requires the use of a special barrier fluid with a density of up to 21 g/cm, which has physical and chemical properties with formation fluid and oil.

The hydraulic protection consists of two chambers connected by a tube. Changes in the volume of liquid dielectric in the engine are compensated by the flow of barrier liquid from one chamber to another. In closed-type hydraulic protection, rubber diaphragms are used. Their elasticity compensates for changes in oil volume.

24. Conditions for well flow, determination of energy and specific gas consumption during operation of a gas-liquid lift.

Well flow conditions.

Well flowing occurs if the pressure difference between the reservoir and the bottom hole is sufficient to overcome the back pressure of the liquid column and pressure loss due to friction, that is, flowing occurs under the influence of hydrostatic pressure of the liquid or the energy of the expanding gas. Most wells flow due to gas energy and hydrostatic pressure simultaneously.

Gas contained in oil has a lifting force, which manifests itself in the form of pressure on the oil. The more gas is dissolved in oil, the lower the density of the mixture and the higher the liquid level rises. Having reached the mouth, the liquid overflows and the well begins to gush. The general mandatory condition for the operation of any flowing well will be the following basic equality:

Рс = Рг+Рtr+ Ру; Where

Рс - bottomhole pressure, RG, Рtr, Ру - hydrostatic pressure of the liquid column in the well, calculated vertically, pressure loss due to friction in the tubing and back pressure at the wellhead, respectively.

There are two types of well flowing:

· Gouting of a liquid that does not contain gas bubbles - artesian gushing.

· Gouting of a liquid containing gas bubbles that facilitate gushing is the most common method of gushing.

Electrical equipment, depending on the current supply circuit, includes either a complete transformer substation for submersible pumps (KTPPS), or a transformer substation (TS), a control station and a transformer.

Electricity from the transformer (or from the KTPPN) to the submersible electric motor is supplied through a cable line, which consists of a surface power cable and a main cable with an extension cord. The connection of the ground cable to the main cable of the cable line is carried out in a terminal box, which is installed at a distance of 3-5 meters from the wellhead.

The site for the placement of ground-based electrical equipment is protected from flooding during flood periods and cleared of snow in winter and must have entrances that allow free installation and dismantling of equipment. Responsibility for the working condition of the sites and entrances to them rests with the CDNG.

Control station

Using the control station, manual control of the engine, automatic shutdown of the unit when the liquid supply is stopped, zero protection, protection against overload and shutdown of the unit in the event of short circuits are carried out. During operation of the unit, a centrifugal current pump sucks liquid through a filter installed at the pump inlet and forces it through pump pipes to the surface. Depending on the pressure, i.e. liquid lifting heights, pumps with different numbers of stages are used. A check valve and drain valve are installed above the pump. The check valve is used to maintain the tubing, which makes it easier to start the engine and control its operation after starting. During operation, the check valve is held in the open position by pressure from below. The drain valve is installed above the return valve, and is used to drain fluid from the tubing when lifting them to the surface.

Autotransformer

A transformer (autotransformer) is used to increase the voltage from 380 (field network) to 400-2000 V.

The transformers are oil cooled. They are designed for outdoor use. On the high side of the transformer windings, fifty taps are made to supply the optimal voltage to the electric motor, depending on the cable length, motor load and mains voltage.

Switching taps is carried out with the transformer completely turned off.

The transformer consists of a magnetic core, high voltage and low voltage windings, a tank, a cover with inputs and an expander with an air dryer.

The transformer tank is filled with transformer oil having a breakdown voltage of at least 40 kW.

On transformers with a power of 100 - 200 kW, a thermosyphon filter is installed to clean transformer oil from aging products.

Mounted on the tank cover:

HV winding tap switch drive (one or two);

Mercury thermometer for measuring the temperature of the upper layers of oil;

Removable HV and LV bushings, allowing replacement of insulators without lifting the removable part;

Conservator with oil indicator and air dryer;

Metal box to protect inputs from dust and moisture.

An oil seal air dryer is designed to remove moisture and clean industrial pollution air entering the transformer when temperature fluctuations oil level

Wellhead fittings

Wellhead fittings are designed to divert production from the well to the flow line and seal the interpipe space.

The wellhead fittings of a well prepared for launching an ESP are equipped with pressure gauges, a check valve on the line connecting the annulus with the discharge, a choke chamber (if technologically feasible) and a pipe for research. Responsibility for the implementation of this point lies with the CDNG.

The wellhead fittings, in addition to the functions performed in all production methods, must ensure the tightness of the reciprocating polished rod moving in it. The latter is a mechanical connection between the rod column and the head of the SK balancer.

Wellhead fittings, manifolds and flow lines with complex configurations complicate the flow hydrodynamics. Near-well equipment located on the surface is relatively accessible and can be relatively easily cleaned of deposits, mainly by thermal methods.

The wellhead fittings of wells through which water is pumped into the formation are subjected to hydraulic testing in the manner established for Christmas tree fittings.

Underground equipment ESP

Underground equipment includes tubing, pumping unit and eclectic armored cable.

Centrifugal pumps for pumping liquid from a well are not fundamentally different from conventional centrifugal pumps used for pumping liquids on the surface of the earth. However, the small radial dimensions due to the diameter of the casing into which centrifugal pumps are lowered, the practically unlimited axial dimensions, the need to overcome high pressures and the operation of the pump in a submerged state have led to the creation of centrifugal pumping units of a specific design. Externally, they are no different from a pipe, but the internal cavity of such a pipe contains a large number of complex parts that require advanced manufacturing technology.

Submersible centrifugal electric pumps (PTsEN) are multi-stage centrifugal pumps with the number of stages in one block up to 120, driven by a specially designed submersible electric motor (SEM). The electric motor is powered from the surface by electricity supplied via a cable from a step-up autotransformer or transformer through a control station in which all instrumentation and automation are concentrated. The PTsEN is lowered into the well below the calculated dynamic level, usually 150 - 300 m. The liquid is supplied through tubing, to the outer side of which an electric cable is attached with special belts. In the pump unit, between the pump itself and the electric motor, there is an intermediate link called a protector or hydraulic protection. The PCEN installation (Figure 3) includes an oil-filled electric motor SEM 1; hydraulic protection link or protector 2; pump receiving grid for collecting liquid 3; multistage centrifugal pump PCEN 4; NKT 5; armored three-core electrical cable 6; belts for attaching the cable to the tubing 7; wellhead fittings 8; a drum for winding cables during hoisting operations and storing a certain supply of cable 9; transformer or autotransformer 10; control station with automation 11 and compensator 12.

The pump, protector and motor are separate units connected by bolted studs. The ends of the shafts have splined joints, which are joined when assembling the entire installation. If it is necessary to lift liquid from great depths, the PCEN sections are connected to each other so that the total number of stages reaches 400. The liquid sucked in by the pump sequentially passes through all stages and leaves the pump with a pressure equal to the external hydraulic resistance.

Figure 3 - General diagram of well equipment with installation of a submersible centrifugal pump

UPTsEN are distinguished by low metal consumption, a wide range of operating characteristics, both in terms of pressure and flow, fairly high efficiency, the ability to pump out large quantities of liquid and a long turnaround period. It should be recalled that the average liquid supply in Russia for one UPTsEN is 114.7 t/day, and for USHSN - 14.1 t/day.

All pumps are divided into two main groups; conventional and wear-resistant design. The overwhelming majority of the existing pump stock (about 95%) is of conventional design.

Wear-resistant pumps are designed to operate in wells that contain small amounts of sand and other mechanical impurities (up to 1% by weight). According to the transverse dimensions, all pumps are divided into 3 conditional groups: 5; 5A and 6, which means the nominal diameter of the casing, in inches, into which the pump can be run.

Group 5 has an outer case diameter of 92 mm, group 5A - 103 mm and group b - 114 mm. The rotation speed of the pump shaft corresponds to the frequency of the alternating current in the electrical network. In Russia, this frequency is 50 Hz, which gives a synchronous speed (for a two-pole machine) of 3000 min-1. The PCEN code contains their main nominal parameters, such as flow and pressure when operating in optimal mode. For example, ESP5-40-950 means a centrifugal electric pump of group 5 with a flow of 40 m3/day (by water) and a head of 950 m. ESP5A-360-600 means a pump of group 5A with a flow of 360 m3/day and a head of 600 m.

Figure 4 - Typical characteristics of a submersible centrifugal pump

The code for wear-resistant pumps contains the letter I, which means wear resistance. In them, the impellers are made not of metal, but of polyamide resin (P-68). In the pump casing, approximately every 20 stages, intermediate rubber-metal shaft-centering bearings are installed, as a result of which the wear-resistant pump has fewer stages and, accordingly, pressure.

The end supports of the impellers are not cast iron, but in the form of pressed rings made of hardened steel 40X. Instead of textolite support washers, washers made of oil-resistant rubber are used between the impellers and guide vanes.

All types of pumps have a passport operating characteristic in the form of dependence curves Н(Q) (pressure, flow), з(Q) (efficiency, flow), N(Q) (power consumption, flow). Typically, these dependencies are given in the range of operating flow rates or in a slightly larger interval (Fig. 11.2).

Any centrifugal pump, including PCEN, can operate with the discharge valve closed (point A: Q = 0; H = Hmax) and without backpressure at the discharge (point B: Q = Qmax; H = 0). Since the useful work of the pump is proportional to the product of the supply and the pressure, then for these two extreme modes of pump operation the useful work will be equal to zero, and therefore the efficiency will be equal to zero. At a certain ratio (Q and H, due to minimal internal losses of the pump, efficiency reaches a maximum value of approximately 0.5 - 0.6. Typically, pumps with low flow and small diameter impellers, as well as with a large number stages have a reduced efficiency. The flow and pressure corresponding to the maximum efficiency are called the optimal mode of operation of the pump. The dependence s(Q) around its maximum decreases smoothly, therefore it is quite acceptable to operate the PTsEN in modes different from the optimal in one direction or the other by a certain amount. The limits of these deviations will depend on the specific characteristics of the PTsEN and must correspond to a reasonable reduction in the efficiency of the pump (by 3 - 5%). This determines a whole range of possible operating modes of the PTsEN, which is called the recommended area (see Fig. 11.2, shading).

Selection of a pump for wells essentially comes down to choosing a standard size PCEN so that, when lowered into a well, it operates under optimal or recommended conditions when pumping a given well flow rate from a given depth.

Currently produced pumps are designed for nominal flow rates from 40 (ETSN5-40-950) to 500 m3/day (ETSN6-500-750) and pressures from 450 m (ETSN6-500-450) to 1500 m (ETSN6-100- 1500). In addition, there are pumps for special purposes, for example, for pumping water into formations. These pumps have flow rates up to 3000 m3/day and heads up to 1200 m.

The pressure that a pump can overcome is directly proportional to the number of stages. Developed in one stage under optimal operating conditions, it depends, in particular, on the dimensions of the impeller, which in turn depend on the radial dimensions of the pump. With an outer diameter of the pump housing of 92 mm, the average pressure developed by one stage (when operating on water) is 3.86 m with fluctuations from 3.69 to 4.2 m. With an outer diameter of 114 mm, the average pressure is 5.76 m with fluctuations from 5.03 to 6.84 m.

The pumping unit consists of a pump (Figure 4, a), a hydraulic protection unit (Figure 4, 6), a submersible electric motor (Figure 4, c), a compensator (Figure 4, d) attached to the lower part of the SEM.

The pump consists of the following parts: head 1 with a ball check valve to prevent fluid from draining from the tubing during stops; upper sliding support heel 2, which receives partial axial load due to the difference in pressure at the inlet and outlet of the pump; upper sliding bearing 3, centering the upper end of the shaft; pump housing 4; guide vanes 5, which rest on each other and are kept from rotation by a common tie in the housing 4; impellers 6; pump shaft 7, which has a longitudinal key on which impellers with a sliding fit are mounted. The shaft also passes through the guide vane of each stage and is centered in it by the impeller bushing, as in a bearing; lower plain bearing 8; base 9, covered with a receiving mesh and having round inclined holes in the upper part for supplying liquid to the lower impeller; end sliding bearing 10. In pumps of early designs that are still in operation, the structure of the lower part is different. Along the entire length of base 9 there is an oil seal made of lead-graphite rings, separating the receiving part of the pump and the internal cavities of the engine and hydraulic protection. Below the oil seal, a three-row angular contact ball bearing is mounted, lubricated with thick oil under some excess pressure relative to the external one (0.01 - 0.2 MPa).

Figure 4 - Design of a submersible centrifugal unit

a - centrifugal pump; b - hydraulic protection unit; c - submersible electric motor; g - compensator

In modern ESP designs, there is no excess pressure in the hydraulic protection unit, so there is less leakage of liquid transformer oil with which the motor is filled, and the need for a lead-graphite oil seal has disappeared.

The cavities of the engine and the receiving part are separated by a simple mechanical seal, the pressure on both sides of which is the same. The length of the pump casing usually does not exceed 5.5 m. When the required number of stages (in pumps developing high pressures) cannot be placed in one casing, they are placed in two or three separate casings, constituting independent sections of one pump, which are docked together at lowering the pump into the well

The hydraulic protection unit is an independent unit attached to the PTsEN with a bolted connection (in Figure 4, the unit, like the PTsEN itself, is shown with shipping plugs sealing the ends of the units)

The upper end of shaft 1 is connected by a splined coupling to the lower end of the pump shaft. A lightweight mechanical seal 2 separates the upper cavity, which may contain well fluid, from the cavity below the seal, which is filled with transformer oil, which, like the well fluid, is under pressure equal to the pressure at the pump immersion depth. Below the mechanical seal 2 there is a sliding friction bearing, and even lower - unit 3 - the support foot, which receives the axial force of the pump shaft. The sliding support foot 3 operates in liquid transformer oil.

Below is a second mechanical seal 4 for more reliable sealing of the engine. It is structurally no different from the first. Underneath it there is a rubber bag 5 in the housing 6. The bag hermetically separates two cavities: the internal cavity of the bag filled with transformer oil, and the cavity between the housing 6 and the bag itself, into which the external well fluid has access through a check valve 7.

The well fluid penetrates through the valve 7 into the cavity of the housing 6 and compresses the rubber bag with oil to a pressure equal to the external one. Liquid oil penetrates through the gaps along the shaft to the mechanical seals and down to the motor.

Two designs of water protection devices have been developed. The hydraulic protection of the main engine differs from the described hydraulic protection of the main engine by the presence of a small turbine on the shaft, which creates increased pressure liquid oil in the inner cavity of the rubber bag 5.

The external cavity between the housing 6 and the bag 5 is filled with thick oil that feeds the angular contact ball bearing PCEN of the previous design. Thus, the hydraulic protection unit of the main engine with an improved design is suitable for use in conjunction with the previous types of PTsEN, which are widely used in the fields. Previously, hydraulic protection was used, the so-called piston-type protector, in which excess pressure on the oil was created by a spring-loaded piston. The new designs of the GD and G turned out to be more reliable and durable. Temperature changes in the volume of oil when it is heated or cooled are compensated by attaching a rubber bag - a compensator - to the bottom of the motor.

The PCEN is driven by special vertical asynchronous oil-filled two-pole electric motors (SEM). Pump electric motors are divided into 3 groups: 5; 5A and 6.

Since the electric cable does not pass along the body of the electric motor, unlike the pump, the diametrical dimensions of the motors of the named groups are slightly larger than those of the pumps, namely: group 5 has a maximum diameter of 103 mm, group 5A - 117 mm and group 6 - 123 mm.

The SED marking includes the rated power (kW) and diameter; for example, PED65-117 means: a 65 kW submersible electric motor with a housing diameter of 117 mm, i.e. included in group 5A.

Small permissible diameters and high powers (up to 125 kW) force us to make engines of great length - up to 8 m, and sometimes more. Top part The PED is connected to the lower part of the hydraulic protection unit using bolted studs. The shafts are joined with splined couplings.

The upper end of the motor drive shaft is suspended on the sliding heel 1, running in oil. Below is the cable entry unit 2. Typically this unit is a plug cable connector. This is one of the most vulnerable points in the pump, due to a violation of the insulation of which the installations fail and require lifting; 3 - output wires of the stator winding; 4 - upper radial sliding friction bearing; 5 - section of the end ends of the stator winding; 6 - stator section, assembled from stamped transformer iron plates with grooves for pulling stator wires. The stator sections are separated from each other by non-magnetic packages in which the radial bearings 7 of the electric motor shaft 8 are strengthened. The lower end of the shaft 8 is centered by the lower radial sliding friction bearing 9. The PED rotor also consists of sections assembled on the motor shaft from stamped transformer iron plates. Aluminum rods, short-circuited with conductive rings, are inserted into the slots of the squirrel wheel type rotor on both sides of the section. Between the sections, the motor shaft is centered in bearings 7. A hole with a diameter of 6 - 8 mm passes through the entire length of the motor shaft to allow oil to pass from the lower cavity to the upper one. There is also a groove along the entire stator through which oil can circulate. The rotor rotates in liquid transformer oil with high insulating properties. At the bottom of the motor there is a mesh oil filter 10. Head 1 of the compensator (see Fig. 11.3, d) is attached to the lower end of the motor; bypass valve 2 serves to fill the system with oil. The protective casing 4 in the lower part has holes for transmitting external liquid pressure to the elastic element 3. When the oil cools, its volume decreases and the well fluid enters the space between the bag 3 and the casing 4 through the holes. When heated, the bag expands and the liquid through the same holes comes out of the casing.

PEDs used for the operation of oil production wells usually have powers from 10 to 125 kW.

To maintain reservoir pressure, special submersible pumping units equipped with 500 kW motors are used. The supply voltage in SEDs ranges from 350 to 2000 V. When high voltages it is possible to proportionally reduce the current when transmitting the same power, and this makes it possible to reduce the cross-section of the current-carrying cable cores, and, consequently, the transverse dimensions of the installation. This is especially important with high electric motor powers. The nominal rotor slip of the motor is from 4 to 8.5%, efficiency is from 73 to 84%, permissible ambient temperatures are up to 100 °C.

When the motor operates, a lot of heat is generated, so cooling is required for normal operation of the motor. This cooling is created due to the continuous flow of formation fluid through the annular gap between the motor housing and the casing. For this reason, paraffin deposits in the tubing during pump operation are always significantly less than with other operating methods.

In production conditions, there is a temporary blackout of power lines due to thunderstorms, broken wires, due to icing, etc. This causes the UPTsEN to stop. In this case, under the influence of the liquid column flowing from the tubing through the pump, the pump shaft and stator begin to rotate in the opposite direction. If at this moment the power supply is restored, the motor will begin to rotate in the forward direction, overcoming the inertia force of the liquid column and rotating masses.

In this case, inrush currents may exceed permissible limits, and the installation will fail. To prevent this from happening, a ball check valve is installed in the discharge part of the PTsEN, which prevents fluid from draining from the tubing.

The check valve is usually located in the pump head. The presence of a check valve complicates the lifting of the tubing during repair work, since in this case the pipes are lifted and unscrewed with liquid. In addition, it is dangerous in terms of fire. To prevent such phenomena, a drain valve is installed above the check valve in a special coupling. In principle, a drain valve is a coupling into the side wall of which a short bronze tube is inserted horizontally, sealed at the inner end. Before lifting, a short metal dart is thrown into the tubing. The impact of the dart breaks off the bronze tube, causing the side hole in the coupling to open and drain the fluid from the tubing.

Other devices for draining liquid have also been developed and installed above the check valve of the PTsEN. These include the so-called prompters, which make it possible to measure the inter-tubular pressure at the depth of the pump run with a downhole pressure gauge lowered into the tubing, and establish a connection between the inter-tubular space and the measuring cavity of the pressure gauge.

It should be noted that the engines are sensitive to the cooling system, which is created by the fluid flow between the casing and the motor housing. The speed of this flow and the quality of the liquid affect temperature regime PED. It is known that water has a heat capacity of 4.1868 kJ/kg-°C, while pure oil has a heat capacity of 1.675 kJ/kg-°C. Therefore, when pumping out watered well products, the cooling conditions for the motor are better than when pumping pure oil, and its overheating leads to insulation failure and engine failure. Therefore, the insulating qualities of the materials used affect the operating life of the installation. It is known that the heat resistance of some insulation used for motor windings has already been increased to 180 °C, and operating temperatures to 150 °C. To control the temperature, simple electrical temperature sensors have been developed that transmit information about the temperature of the motor to the control station via a power electric cable without the use of an additional core. Similar devices are available for transmitting to the surface constant information about the pressure at the pump intake. In emergency conditions, the control station automatically turns off the motor.

The SEM is powered by electricity through a three-core cable, lowered into the well in parallel with the tubing. The cable is attached to the outer surface of the tubing with metal bands, two for each pipe. The cable operates in difficult conditions. Its upper part is in a gas environment, sometimes under significant pressure, the lower part is in oil and is subjected to even greater pressure. When lowering and lifting the pump, especially in curved wells, the cable is subjected to strong mechanical stress (clamps, friction, jamming between the string and tubing, etc.). The cable transmits electricity at high voltages. The use of high-voltage motors makes it possible to reduce the current and, therefore, the cable diameter. However, the cable for powering a high-voltage PED must have more reliable and sometimes thicker insulation. All cables used for UPTsEN are covered with elastic galvanized steel tape on top to protect against mechanical damage. The need to place the cable on the outer surface of the PTsEN reduces the dimensions of the latter. Therefore, a flat cable is laid along the pump, its thickness is approximately 2 times less than the diameter of the round one, with the same cross-sections of the conductors.

All cables used for UPTsEN are divided into round and flat. Round cables have rubber (oil-resistant rubber) or polyethylene insulation, which is reflected in the code: KRBK means round armored rubber cable or KRBP - armored rubber flat cable. When using polyethylene insulation, P is written in the code instead of the letter P: KPBK - for round cable and KPBP - for flat cable.

The round cable is attached to the tubing, and the flat cable is attached only to the lower pipes of the tubing string and to the pump. The transition from a round cable to a flat cable is spliced ​​by hot vulcanization in special molds, and if such a splice is performed poorly, it can serve as a source of insulation damage and failures. Recently, they have been switching only to flat cables running from the motor drive along the tubing string to the control station. However, the manufacture of such cables is more difficult than round ones (Table 11.1).

There are some other types of polyethylene insulated cables not mentioned in the table. Cables with polyethylene insulation are 26 - 35% lighter than cables with rubber insulation. Rubber insulated cables are designed for use at rated voltage electric current no more than 1100 V, at ambient temperatures up to 90 °C and pressure up to 1 MPa. Cables with polyethylene insulation can operate at voltages up to 2300 V, temperatures up to 120 ° C and pressures up to 2 MPa. These cables are more resistant to gas and high pressure.

All cables are armored with corrugated galvanized steel tape, which gives them the required strength.

The primary windings of three-phase transformers and autotransformers are always designed for the voltage of the field power supply network, i.e. 380 V, to which they are connected through control stations. The secondary windings are designed for the operating voltage of the corresponding motor to which they are connected by cable. These operating voltages in various SEDs vary from 350V (SED10-103) to 2000V (SED65-117; SED125-138). To compensate for the voltage drop in the cable from the secondary winding, 6 taps are made (one type of transformer has 8 taps), allowing you to regulate the voltage at the ends of the secondary winding by rearranging the jumpers. Rearranging the jumper by one step increases the voltage by 30 - 60 V, depending on the type of transformer.

All non-oil-filled, air-cooled transformers and autotransformers are covered with a metal casing and are designed for installation in a sheltered location. They are equipped with underground installation, so their parameters correspond to this PED.

Recently, transformers have become more widespread, as this allows for continuous monitoring of the resistance of the secondary winding of the transformer, cable and stator winding of the motor. When the insulation resistance decreases to the set value (30 kOhm), the installation automatically turns off.

With autotransformers that have a direct electrical connection between the primary and secondary windings, such insulation monitoring cannot be carried out.

Transformers and autotransformers have an efficiency of about 98 - 98.5%. Their weight, depending on power, ranges from 280 to 1240 kg, dimensions from 1060 x 420 x 800 to 1550 x 690 x 1200 mm.

The operation of the UPTsEN is controlled by the PGH5071 or PGH5072 control station. Moreover, the PGH5071 control station is used for autotransformer power supply of the motor, and PGH5072 - for transformer power supply. PGH5071 stations provide instantaneous shutdown of the installation when current-carrying elements are shorted to ground. Both control stations provide the following capabilities for monitoring and controlling the operation of the UPTsEN.

1. Manual and automatic (remote) switching on and off the installation.

2. Automatic switching on of the installation in self-starting mode after the voltage supply in the field network is restored.

3. Automatic operation of the installation in periodic mode (pumping, accumulation) according to the established program with a total time of 24 hours.

4. Automatic switching on and off of the unit depending on the pressure in the flow manifold when automated systems group collection of oil and gas.

5. Instant shutdown of the installation in case of short circuits and in case of current overloads of 40% exceeding the normal operating current.

6. Short-term shutdown for up to 20 s when the motor is overloaded by 20% of the nominal value.

7. Short-term (20 s) shutdown when the liquid supply to the pump is interrupted.

The control station cabinet doors are mechanically interlocked with a switch block. There is a tendency to switch to non-contact, hermetically sealed control stations with semiconductor elements, which, as experience in their operation has shown, are more reliable and not susceptible to dust, moisture and precipitation.

Control stations are designed for installation in barn-type premises or under a canopy (in southern regions) at ambient temperatures from -35 to +40 °C.

The mass of the station is about 160 kg. Dimensions 1300 x 850 x 400 mm. The UPTsEN delivery set includes a drum with a cable, the length of which is determined by the customer.

During the operation of the well, for technological reasons, the pump suspension depth has to be changed. In order not to cut or extend the cable during such suspension changes, the cable length is taken according to the maximum suspension depth of a given pump and at shallower depths its excess is left on the drum. The same drum is used for winding cable when lifting PTsEN from wells.

With a constant suspension depth and stable pump operating conditions, the end of the cable is tucked into the junction box, and there is no need for a drum. In such cases, during repairs, a special drum is used on a transport trolley or on a metal sled with a mechanical drive to constantly and uniformly pull the cable removed from the well and wind it onto the drum. When the pump is released from such a drum, the cable is fed evenly. The drum is driven by an electric drive with reverse and friction to prevent dangerous tension. At oil producing enterprises with a large number of ESPs, they use a special ATE-6 transportation unit based on the KaAZ-255B all-terrain cargo vehicle to transport a cable drum and other electrical equipment, including a transformer, pump, engine and hydraulic protection unit.

For loading and unloading the drum, the unit is equipped with folding directions for rolling the drum onto the platform and a winch with a traction force on the rope of 70 kN. The platform also has a hydraulic crane with a lifting capacity of 7.5 kN with a boom reach of 2.5 m. The cable of the lowered pumping unit is passed through the gland seals of the wellhead and sealed in it using a special detachable sealing flange in the wellhead cross.

A typical wellhead fitting equipped for the operation of a PTsEN (Figure 5) consists of a cross 1, which is screwed onto the casing.

Figure 5 - Wellhead fittings equipped with PTsEN

The crosspiece has a detachable liner 2 that takes the load from the tubing. A seal made of oil-resistant rubber 3 is applied to the liner, which is pressed by a split flange 5. Flange 5 is pressed with bolts to the flange of the cross and seals the cable outlet 4.

The fittings provide for the removal of annular gas through pipe 6 and check valve 7. The fittings are assembled from standardized units and shut-off valves. It can be relatively easily rebuilt for wellhead equipment when operating with sucker rod pumps.

The Borets company produces a wide range of submersible pumps with a capacity from 10 to 6128 m 3 /day and a pressure from 100 to 3500 m.

Borets recommends a specific operating range for all pumps. To ensure optimum efficiency and maximum TBO, the pump must be operated within this range.

To achieve the best results from operating pumps in real well conditions and to meet Customer requirements, our company offers several types of assemblies and designs of pump stages.

Borets pumps can be operated under difficult conditions, including increased solids content, gas content and temperature of the pumped liquid. To increase operational reliability when working in conditions of increased abrasive environmental influences, pumps of compression, abrasion-resistant compression and package assembly types are used.

The Borets pumps use the following stages, which differ from each other in design:

• ESP is a two-support working stage.
• ECNMIK is a single-support stage with a balanced impeller with an extended hub.
• ECNDP is a two-support stage produced by powder metallurgy.
  Pumps with ECP stages are characterized by high resistance to corrosion, wear in friction pairs and water abrasive wear. In addition to this, due to the cleanliness of the flow channels of the stage impeller, these pumps have increased energy saving efficiency.

Pump heads and bases are made of high-strength steel. For aggressive downhole conditions, the heads and bases are made of corrosion-resistant steels. When operating in difficult conditions, the pumps are equipped with radial bearings made of tungsten carbide alloy, which prevent radial wear and vibration. To operate ESPs in aggressive environments, the Borets company uses corrosion-resistant and wear-resistant metallized coatings applied to the body and end parts. These coatings have high hardness and ductility, which prevents them from cracking when equipment bends during hoisting operations.

To reduce salt deposits and prevent corrosion of ESP parts when operating equipment in an aggressive chemical environment at elevated temperatures, the Borets company has developed an anti-salt polymer coating. The coating is applied to steps, pipes, end pieces and fasteners. The use of coating reduces scale deposits on pump stages, and also increases corrosion, chemical and wear resistance.

The operation of wells using submersible centrifugal pumps (ESP) is currently the main method of oil production in Russia. These installations extract about two-thirds of the total annual oil production in our country to the surface.

Electric centrifugal well pumps (ESP) belong to the class of dynamic vane pumps, characterized by higher flow rates and lower pressures compared to positive displacement pumps.

The supply range of downhole electric centrifugal pumps is from 10 to 1000 m 3 /day or more, the pressure is up to 3500 m. In the supply range of over 80 m 3 /day, the ESP has the highest efficiency among all mechanized oil production methods. In the flow range from 50 to 300 m 3 /day, the pump efficiency exceeds 40%.

The purpose of electric centrifugal well pumps is to extract oil from a well with a water content of up to 99%, a mechanical impurity content of up to 0.01% (0.1 g/l) and a hardness of up to 5 Mohs points; hydrogen sulfide up to 0.001%, gas content up to 25%. In the corrosion-resistant version, the hydrogen sulfide content can be up to 0.125% (up to 1.25 g/l). In the wear-resistant version, the content of mechanical impurities is up to 0.5 g/l. The permissible rate of increase in wellbore curvature is up to 20 per 10 m. The angle of deviation of the wellbore axis from the vertical is up to 400.

The advantage of ESPs is their greater potential for automation of operation and remote condition monitoring compared to rod units. In addition, ESPs are less affected by well curvature.

The disadvantages of electric centrifugal pumps are the deterioration of performance in a corrosive environment, when sand is removed, in conditions of high temperature and high gas factor, a decrease in operating parameters with an increase in liquid viscosity (with a viscosity of more than 200 cP, the operation of an ESP becomes impossible).

The main manufacturers of submersible centrifugal pumps in Russia are the Almetyevsk Pump Plant (JSC ALNAS), the Lebedyansky Machine-Building Plant (JSC LEMAZ), and the Moscow plant Borets. Interesting developments are also proposed by other organizations, for example, the Perm plant Novomet JSC, which produces original stages of submersible centrifugal pumps using powder metallurgy.

ESPs in Russia are manufactured in accordance with technical specifications, while abroad - in accordance with API requirements.

The most famous foreign manufacturers of ESP units are REDA, Centrilift, ODI and ESP (USA). IN last years ESP manufacturers from the People's Republic of China (Temtext) are also very active.

These guidelines provide the basic design diagrams of ESPs, features of their design and operating principle.

To independently test the acquired knowledge, a list of control questions is provided at the end of the guidelines.

The purpose of this laboratory work is to study the design of a submersible centrifugal pump.

2. Theory

2.1. General installation diagram of a submersible electric centrifugal pump

To date, a large number of different schemes and modifications of ESP installations have been proposed. Figure 2.1 shows one of the diagrams for equipping a production well with the installation of a submersible centrifugal electric pump.

Rice. 2.1. Installation diagram of a submersible centrifugal pump in a well

The diagram shows: compensator 1, submersible electric motor (SEM) 2, protector 3, receiving mesh 4 with gas separator 5, pump 6, fishing head 7, pump check valve 8, drain valve 9, tubing string 10, elbow 11, flow line 12, wellhead check valve 13, pressure gauges 14 and 16, wellhead fittings 15, cable line 17, connecting ventilation box 18, control station 19, transformer 20, dynamic fluid level in the well 21, belts 22 for attaching the cable line to the tubing and pumping unit and production casing of well 23.

When the installation is operating, pump 6 pumps liquid from the well to the surface through tubing pipes 10. Pump 6 is driven by a submersible electric motor 2, power to which is supplied from the surface via cable 17. Motor 2 is cooled by the flow of well products.

Ground-based electrical equipment - control station 19 with transformer 20 - is designed to convert the field power supply voltage to a value that provides optimal voltage at the input to electric motor 2, taking into account losses in cable 17, and

Figure 1.1 - Installation diagram of a submersible centrifugal pump in a well.

also for controlling the operation of a submersible installation and protecting it under abnormal conditions.

The maximum free gas content at the pump inlet, permissible according to domestic technical conditions, is 25%. If there is a gas separator at the ESP intake, the permissible gas content increases to 55%. Foreign ESP manufacturers recommend using gas separators in all cases where the input gas content is more than 10%.

2.2. Designs of main components and parts of the pump

The main elements of any centrifugal pump are impellers, shaft, housing, radial and axial supports (bearings), seals that prevent internal and external fluid leaks.

Electric centrifugal well pumps are multistage. The impellers are located sequentially on the shaft. Each wheel has a guide vane, which converts the velocity energy of the fluid into pressure energy and then directs it to the next wheel. The wheel and guide vane form the pump stage.

In multistage pumps with a sequential arrangement of wheels, units are provided to relieve axial forces.

2.2.1. Pump stages

The pump stage is the main working element of a downhole centrifugal pump, through which energy is transferred from the liquid pump. The stage consists (Fig. 2.2) of an impeller 3 and a guide vane 1.

Rice. 2.2. ESP stage

5 – lower support washer; 6 – protective sleeve;

7 – upper support washer; 8 - shaft

The pressure of one stage is from 3 to 7 m of water column. The small pressure value is determined by the small external diameter of the impeller, limited by the internal diameter of the casing. The required pressure values ​​in the pump are achieved by sequential installation of impellers and guide vanes.

The steps are placed in the bore of the cylindrical body of each section. One section can accommodate from 39 to 200 stages (the maximum number of stages in pumps reaches 550 pieces).

To make it possible to assemble an ESP with such a number of stages and to unload the shaft from axial force, a floating impeller is used. Such a wheel is not fixed on the shaft in the axial direction, but moves freely in the gap limited by the supporting surfaces of the guide vanes. A parallel key keeps the wheel from turning.

The individual axial support of each stage consists of a support shoulder of the guide vane of the previous stage and an anti-friction wear-resistant (textolite) washer pressed into the bore of the impeller (item 5, Fig. 2.2). This support (heel) also serves as a front wheel seal, reducing internal leakage in the pump.

At modes approximately 10% higher than the feed corresponding to zero axial force, the impeller can “float” - move upward. To provide reliable support for the wheel, an upper axial support is provided. On the upper individual support, the impeller can also operate under short-term starting conditions. The upper support consists of a support collar on the guide vane and a washer pressed into the impeller bore (item 7, Fig. 2.2).

The main elements of the pump stage can have different designs. In accordance with this, the stages and, in fact, the pumps are classified as follows.

1. According to the design of the impeller blade apparatus:

· with cylindrical (radial) blades (Fig. 2.3, a) and with inclined-cylindrical (radial-axial) blades (Fig. 2.3, b).

In stages with radial guide blades, the transfer channels are located radially. Hydraulically, they are more advanced, but the nominal flow is limited to 125 m 3 /day in pumps with an outer diameter of 86 and 92 mm and to 160 m 3 /day in pumps with an outer diameter of 103 mm and 114 mm.

For impellers with inclined cylindrical blades, the blades enter the region of rotation from the axial to the radial direction, which leads to an inclined position of their leading edge relative to the pump axis. The value of the speed coefficient of such wheels is at the extreme right border of high-speed pumps, approaching diagonal pumps. The feed in such stages is higher.

2. According to the design of the flow channels of the guide apparatus, the stages can have radial and “axial” flow channels.

The designs of steps with radial and axial guide vanes are shown in Fig. 2.3 a, b.

Rice. 2.3. Stage with impeller and guide vane

(a) radial design and (b) radial-axial design

guide vane; 4 – support washers; 5 – shaft; 6 – key

Radial guide vanes have a radial arrangement of flow channels. A stage with such guide devices is hydraulically more advanced, has a simpler geometry, is convenient to manufacture, but has a low flow (20...40 m 3 /day).

The stage with an “axial” guide vane is named conventionally because in it the arrangement of channels that convert the kinetic energy of the flow into potential energy approaches the axial one. A stage with an axial guide vane provides higher flow (40...1000 m 3 /day), simpler geometry and has become widely used in the manufacture of domestic designs of submersible pumps, practically displacing the “radial” stage, which is currently no longer produced.

2. According to the method of installing the impellers on the shaft:

· steps with floating impellers;

· steps with rigidly fixed wheels (used in foreign designs).

3. According to the method of unloading from axial forces:

· steps with impellers unloaded from axial force (Fig. 2.1, 2.2);

· steps unloaded from axial force using an unloading chamber on the side of the rear (main) disk (Fig. 2.4). The chamber is made using a slot seal and through holes in the main disk. This method is used in stages with inclined cylindrical blades.

· steps unloaded from axial force by making radial impellers on the outer side of the rear disk (Fig. 2.5). Radial impellers on the rear disc reduce the pressure acting on it and are mainly used in cylindrical wheels. The wheels, in this case, are called centrifugal-vortex.

Centrifugal vortex wheels were developed and manufactured by Novomet. For their manufacture, the powder metallurgy method is used. The use of centrifugal vortex wheels has a number of advantages: the stage pressure increases by 15...20%; the pump can be used to lift liquids with a high gas content (up to 35% by volume).

Stages with unloaded impellers have an increased service life of the individual lower support of the impeller. But they have complex technology and increased manufacturing complexity. In addition, during operation, a functional failure of the unloading method using the unloading chamber may occur if the unloading holes are clogged and if the upper seal of the impeller is worn.

Rice. 2.4. Design of stages with unloaded impeller

Rice. 2.5. Stages of a centrifugal vortex pump from Novomet

apparatus; 6 – lower support washer; 7 – upper support washer;

8 – pump housing

4. According to the creation of a support for wheels of a floating type, the steps can be of a single-support structure and a double-support structure.

The steps of a single-support design have one individual lower support - the heel - on the side of the front disk.

Double-bearing stages have additional axial support through a textolite pressed ring on the impeller hub at the inlet and the end flange of the guide vane (Fig. 2.6). The additional support enhances the axial support and inter-stage sealing of the steps.

Rice. 2.6. Double stage centrifugal pump

disk; 4 – main ring of the front disc; 5 – rear disc ring

The advantages of the two-support design are the increased life of the main lower support of the stage, more reliable isolation of the shaft from abrasive and corrosive flowing liquid, increased service life and greater rigidity of the pump shaft due to the increased axial lengths of the interstage seals, which also serve as radial bearings in the ESP.

The disadvantage of two-support steps is the increase in labor intensity in manufacturing.

4. According to the execution of the stage, there can be:

· conventional version (ESP);

· wear-resistant (ECNI);

· corrosion-resistant (ECNC).

The stages in pumps of different designs differ from each other in the materials of the working bodies, friction pairs and some structural elements.

The corrosion-resistant and wear-resistant steps usually have two individual lower supports and an elongated hub on the rear disk side, which covers the shaft gap between the wheels from wear (Fig. 2.6).

In the usual version, for the manufacture of impellers and guide vanes, mainly modified cast iron is used, in a friction pair of the upper and lower main support - textolite-cast iron, additional support - textolite-cast iron or rubber-cast iron. In a corrosion-resistant version, wheels and guide devices can be made of ni-resist cast iron. Increased wear resistance - made of wear-resistant cast iron, friction pair in the lower main bearing - rubber-siliconized graphite, additional support - rubber-cast iron, upper bearing - textolite-cast iron. Cast iron wheels can also be replaced with plastic ones made of polyamide resin or carbon fiber, which are resistant to wear by free abrasive and do not swell in water (in wells with a high oil content, as experience has shown, they are less efficient).

The traditional technology for manufacturing steps by Russian manufacturers is casting. The roughness of castings is within the range of Rz 40...80 microns (GOST 2789-83).

A lower roughness (Rz 10) can be obtained using the powder metallurgy technology developed by Novomet JSC. The use of this technology has made it possible to significantly increase the efficiency of the stages and to produce more complex designs of impellers (centrifugal vortex wheels).

2.2.2. Pump bearing units

Bearing units of a downhole centrifugal electric pump are one of the main units that determine the durability and performance of the pump unit. They operate in the medium of the pumped liquid and are plain bearings.

To absorb the axial forces and radial loads acting on the shaft, the ESP uses axial and radial bearings, respectively.

2.2.2.1. Axial supports

The axial force acting on the rotor is created from its own weight, from the pressure difference on the end of the shaft, as well as from the pressure difference and the difference in the areas of the rear and front disk of impellers with a rigid fit on the shaft or floating wheels stuck to the shaft during operation.

A thrust bearing that absorbs axial force is installed either directly in the pump - in the upper part of the section or module section (domestic designs), or in the hydraulic protection of the pump (foreign designs).

Rice. 2.6 – Thrust bearing of the pump ETsNM(K)

1 - hydrodynamic heel; 2, 3 – smooth washers; 4, 5 – rubber washers -

shock absorbers; 6 – upper support (thrust bearing); 7 – lower support (thrust bearing);

10 – fixed bushing of the upper radial bearing; 11 – rotating sleeve

upper radial bearing

A thrust bearing in domestic designs in the usual design (Fig. 2.7) consists of a ring (hydrodynamic heel) 1 with segments on both planes, installed between two smooth washers 2 and 3.

The segments on the hydrodynamic foot washer (moving part of the bearing) 1 are made with an inclined surface with an angle and a flat platform with a length of (0.5...0.7)· (where is the total length of the segment). The segment width is (1…1.4) L. To compensate for inaccuracies in manufacturing and the perception of shock loads, elastic rubber shock absorber washers 4, 5 are placed under the smooth rings, pressed into the upper 6 and lower 7 supports (fixed thrust bearings). The axial force from the shaft is transmitted through the spring ring 8 of the shaft support and the spacer sleeve 9 to the thrust bearing.

The hydrodynamic heel is made with radial grooves, a bevel and a flat part on the friction surface against the thrust bearing. It is usually made from belting (technical fabric with large cells), impregnated with graphite and rubber and vulcanized in a mold. Smooth washers are made of steel 40Х13.

When the heel rotates, the liquid goes from the center to the periphery along the grooves, falls under the bevel and is pumped into the gap between the flat parts of the thrust bearing and the heel. Thus, the thrust bearing slides over the layer of liquid. Such liquid friction in the operating mode of the heel provides a low coefficient of friction, insignificant energy losses due to friction in the heel, and low wear of the heel parts with sufficient axial force that it perceives.

7 – lower bushing

2.2.3. Radial supports

2.2.4. Shaft

2.2.5. Frame

2.3.2.1. Electric motor

2.3.2.2. Water protection

Rice. 3.17. Compensator

Rice. 2.18. Tread

2.3.2.3. cable line

Rice. 2. 20. Check valve

Rice. 2.21. Drain valve

2.4. Designation of ESP and ESP

,

where is the diameter of the pump body;

Engine housing diameter;

Table 2.1

Indicators	ESP Group
Pump outer diameter, mm The outer diameter of the PED, the grooves, falls under the bevel and is pumped into the gap between the flat parts of the thrust bearing and the heel. Thus, the thrust bearing slides over the layer of liquid. Such liquid friction in the operating mode of the heel provides a low coefficient of friction, insignificant energy losses due to friction in the heel, and low wear of the heel parts with sufficient axial force that it perceives. Thrust bearings allow a specific load of up to 3 MPa. In the axial bearings of wear-resistant pumps, more wear-resistant materials of rubbing pairs are used: siliconized graphite SG-P on siliconized graphite SG-P or silicon carbide on silicon carbide. A design option for a thrust bearing in wear-resistant pumps is shown in Fig. 2.8. Rice. 2.8. Wear-resistant pump axial bearing 1 – upper support; 2 – rubber washer; 3 – upper thrust bearing; 4 – lower thrust bearing; 5 – lower support; 6 – upper bushing; 7 – lower bushing 2.2.3. Radial supports Radial loads arising during pump operation are absorbed by radial plain bearings operating in the flow of well production. In the usual design, radial bearings are located in the upper and lower parts of the housing of each section or each module section of the pump. In wear-resistant pumps, to limit the longitudinal bending of the shaft, intermediate radial supports are used, which, depending on the type of pump, are mounted every 16-25 stages (at a distance of 650 to 1000 mm) together with guide vanes. In Fig. 2.7, 2.9, 2.10 show the designs of the upper, lower and intermediate radial bearings, respectively. The radial bearing (Fig. 2.9) is a cylindrical housing with axial holes for the flow of pumped liquid and a hub 3, inside of which a sleeve 4 is pressed. The contact pair in the bearing is a fixed sleeve 4 and a movable sleeve 5. Material: steel 40X13, brass L63. Rice. 2.8. Lower radial bearing assembly of the pump 1 – shaft; 2 – pump stage; 3 – bearing hub; 4 – hub bushing; 5 – shaft sleeve; 6 – support washer The intermediate bearing (Fig. 2.10) consists of a cylindrical housing having axial channels for the passage of fluid flow and a cylindrical hub 3, inside of which a sleeve 4 made of oil-resistant rubber is fixed. The inner surface has longitudinal channels that allow fluid to pass between the shaft and the bushing to lubricate the bearing assembly. Shaft sleeve 5 is made of siliconized graphite SG-P or silicon carbide. Rice. 2.10. Intermediate radial bearing unit 1 – shaft; 2 – pump stage; 3 – bearing hub; 4 – hub bushing; 5 – shaft sleeve. In addition to the main radial bearings, brass bushings are installed on the shaft between the impellers, which, rotating in the holes of the guide vanes, also serve as radial plain bearings in each stage of the pump. 2.2.4. Shaft The ESP pump shaft is assembled, connected at the ends using splined couplings at the junctions of sections and modules. The shaft and couplings are made from rods with a special surface finish. Corrosion-resistant high-strength steel is used as materials for rods. To transmit torque to the impellers, a keyed connection is used. A common keyway (groove) is milled on the shaft, into which cleanly drawn square key rods made of brass or steel are placed. The ends of the shaft are located in radial plain bearings. 2.2.5. Frame The pump body is a cylindrical pipe that combines the constituent units and elements of the pump and forms its sections (in sectional pumps) or modules (in modular pumps). In accordance with the design diagram of the pump, sections or modules are connected to each other using a flange connection or a flange-to-body connection. Housings are made of low carbon steel 2.3. Basic diagrams and composition of submersible electric centrifugal pumping units A downhole electric centrifugal unit consists of a submersible pump, an electric motor and hydraulic protection, which have different design designs. The main ones are given below. 2.3.1. Submersible centrifugal pump The submersible centrifugal pump is manufactured in a sectional (ESP) or modular (ETSNM) design. A sectional pump (ESP), in general, contains a lower section with a receiving mesh (Fig. 2.11), a middle section and an upper section with a fishing head (Fig. 2.12), and there can be several middle sections. Options for completing middle section pumps with an additional input module - a receiving mesh - instead of the lower section (Fig. 2.13), as well as a head module - instead of the upper section are widely used. In this case, the pumps are called modular (ECNM type). In cases where it is necessary to eliminate bad influence free gas for pump operation, a gas separator is installed instead of the input module. The lower section (Fig. 2.11) consists of a housing 1, a shaft 2, a package of stages (impellers 3 and guide vanes 4, an upper bearing 5, a lower bearing 6, an upper axial support 7, a head 8, a base 9, two ribs 10 for protection cable, rubber rings 11, receiving mesh 12, splined coupling 14, covers 15, 16 and intermediate bearings 17. Impellers and guide vanes are installed in series. The guide vanes are tightened by the upper bearing and the base in the housing and are motionless during operation. The impellers are mounted on a shaft, which causes them to rotate through a key. The upper, intermediate and lower bearings are radial supports of the shaft, and the upper axial support carries loads acting along the axis of the shaft. Rubber rings 11 seal the internal cavity of the section from leaks of the pumped liquid. Spline couplings 14 serve to transmit rotation from one shaft to another. During transportation and storage, the sections are closed with covers 15 and 16. The ribs 10 are designed to protect the electrical cable located between them from mechanical damage when lowering and lifting the pump. In Fig. Figure 2.12 shows the middle and upper sections of the pump (the designation of positions here is the same as in Figure 2.11). Rubber ring 13 seals the connection between the sections. The upper section of the pump ends with a fishing head 18. Shown in Fig. 2.13 The input module is used to receive and roughly clean the pumped product from mechanical impurities. The inlet module consists of a base 1 with holes for the passage of well products, a shaft 2, a receiving grid 3 and a splined coupling 4. The base contains sliding shaft bearings and pins 5, with the help of which the module is attached with the upper end to the pump section, and with the lower flange - to protector. Packaging caps 6 and 7 are used for storing and transporting the input module. To increase the permissible gas content of oil raised to the surface and increase the suction capacity in an ESP, the following methods are used: · the use of separators of various designs at the inlet where gas separation occurs; · installation of dispersing devices at the reception, where gas inclusions are crushed and a homogeneous liquid is prepared; · use of combined “staged” pumps (the first stages have a larger flow area - designed for a larger flow); Russian manufacturers produce gas separators in accordance with regulatory documents types: pump modules - gas separators MNG and MNGK; pumping modules – gas separators Lyapkova MN GSL; MNGB5 pump gas separator modules (manufactured by Borets OJSC). By schematic diagram These gas separators are centrifugal. They are separate pump modules mounted in front of the stage package of the lower pump section using flange connections. The shafts of sections or modules are connected by splined couplings. Rice. 2.11. Lower pump section 5 - upper bearing; 6 - lower bearing; 7 - upper axial support; 8 – head; 9 - base, 10 - two ribs to protect the cable; 11.13 - rubber rings; 12 - receiving grid; 14 - splined coupling; 15,16 – covers; 17 - intermediate bearings Rice. 2.12. Middle (a) and upper (b) sections of the pump. Rice. 2.13. Pump input module 1 – base; 2 – shaft; 3 – bearing sleeve; 4 – mesh; 5 – protective sleeve; 6 – splined bushing; 7 - hairpin Fig. 2.14. Pump head module 1 – sealing ring; 2 – rib; 3 – body The use of gas separators at the inlet makes it possible to increase the gas content up to 50%, and in some cases up to 80% (pump module - gas separator MN GSL5, developed by Lebedyansky Machine-Building Plant JSC). In Fig. Figure 2.15 shows a gas separator of the MN(K)-GSL type (designated “K” for corrosion-resistant design). The separator consists of a pipe body 1 with a head 2, a base 3 with a receiving mesh and a shaft 4 with working parts located on it. The head has two groups of cross channels 5, 6 for gas and liquid and a radial bearing bushing 7 is installed. At the base there is a cavity closed with a mesh with channels 8 for receiving the gas-liquid mixture, a thrust bearing 9 and a radial bearing bushing 10. The shaft contains a heel 11, a screw 12, an axial impeller 13 with a supercavitating blade profile, separators 14 and radial bearing bushings 15. The housing contains a liner guide grid. Rice. 2.15. Gas separator type MN(K)-GSL The gas separator operates as follows: the gas-liquid mixture enters through the mesh and holes of the input module onto the auger and then to the working parts of the gas separator. Due to the acquired pressure, the gas-liquid liquid enters the rotating chamber of the separator, equipped with radial ribs, where, under the influence of centrifugal forces, the gas is separated from the liquid. Next, the liquid from the periphery of the separator chamber flows through the channels of the sub to the pump intake, and the gas is discharged into the annulus through inclined holes. In addition to the modular design, gas separators can be built into the lower section of the pump (JSC Borets). Dispersants of the type MNDB5 (manufactured by JSC Borets) are produced in a modular design. They are installed at the pump inlet instead of the inlet module. The maximum permissible free gas content at the dispersant inlet at maximum flow is 55% by volume. When a gas-liquid mixture flows through a dispersant, its homogeneity and the degree of fineness of gas inclusions increase, thereby improving the operation of the centrifugal pump. Instead of the input module, gas separator-disperser modules MNGDB5, manufactured by Borets OJSC, can also be installed. The maximum free gas content at the inlet of the gas separator-disperser at maximum flow is 68% by volume. It should be noted that the modular principle of ESP design, adopted by the domestic pump industry in the late 1980s, is currently being sharply criticized by some consumers and manufacturers of submersible pumping units. This is mainly due to the fact that modular pumps increase the number of flange connections between individual modules (sections, inlet module, fishing head, etc.). In some cases, this leads to a decrease in the ESP's time between failures, which is most evident in those oil-producing areas where a significant proportion of failures are caused by dismemberment and flights of units to the bottom. Therefore, ESP manufacturers are currently completing installations in accordance with the wishes of customers, and different versions of pumps may be found in the fields. For example, the receiving grid can be made in the form of a separate module (Fig. 2.13), or it can be installed directly in the lower section of the pump (Fig. 2.11), which reduces the number of flange connections. Similarly, the fishing head of the pump can be a separate module (Fig. 2.14), or can be built into the upper section of the pump (Fig. 2.12 b), etc. 2.3.2. Submersible motor with water protection 2.3.2.1. Electric motor The main type of submersible electric motors driving a submersible centrifugal pump are asynchronous oil-filled motors with squirrel-cage rotors. At a current frequency of 50 Hz, the synchronous rotation speed of their shaft is 3000 min -1. The motor power reaches 500 kW, current voltage 400...3000 V, operating current 10...100 A. Electric motors with a power from 12 to 70 kW (Fig. 2.16) are single-section and consist of a stator 1, a rotor 2, a head 3, a base 4 and a current input unit 5. Rice. 2.16. Single Section Submersible Motor The stator is made of a pipe into which a magnetic circuit made of sheet electrical steel is pressed. The stator is soft magnetic along its entire length. A three-phase continuous winding made of a special winding wire is laid in the stator slots. The winding phases are connected in a star. Inside the stator there is a rotor, which is a set of packages separated from each other by intermediate bearings and sequentially placed on the shaft. The rotor shaft is made hollow to ensure oil circulation. The rotor packages are made of sheet electrical steel. Copper rods are inserted into the grooves of the packages, welded at the ends with short-circuited copper rings. To create more favorable operating conditions for bearings, the entire set of packages on the shaft is divided into groups secured with locking rings. In this case, a guaranteed working gap of 2...4 mm is provided between the groups. The bearing bushings are sintered, and the housings are made of non-magnetic cast iron - niresist with pressed-in steel bushings and have a device that provides mechanical locking of them from turning in the stator bore. The upper end of the stator is connected to the head, which houses the thrust bearing assembly 6 and the current input assembly 5. The thrust bearing assembly receives axial loads from the weight of the rotor and consists of a base, a rubber ring, a thrust bearing and a heel. The current input unit is an insulating block in which contact sleeves are located, connected by wires to the stator winding. The block is locked in the head with a screw and sealed with a rubber O-ring. The current input unit is an element of the electrical connector for connecting the cable. A check valve 7 is screwed into the head to pump oil through it. The electric motor shaft passes through the head, onto the end of which a splined coupling 8 is put on for connection with the protector shaft. Pins are screwed into the end of head 9 to connect to the tread. At the bottom of the electric motor there is a base in which a filter 10 is located for oil purification. At the base there are channels for communication with the internal cavity of the compensator. The channels are closed by bypass valve 11, which is normally open after installing the engine in the well. The hole into which the bypass valve is screwed is sealed with plug 12 on a lead gasket. A check valve 13 is screwed into the base to pump oil into the electric motor. The lower end of the base is made in the form of a flange with a mounting collar for connecting the compensator. To seal this connection, rubber rings 14 are used. For the period of transportation and storage, the head and base of the electric motor are closed with covers 9 and 15. Electric motors with a power of over 80 kW are usually made in two sections. They consist of upper 1 and lower 2 sections, which are connected when mounting the engine on the well. Each section consists of a stator and a rotor, the structure of which is similar to a single-section electric motor. The electrical connection of the sections to each other is serial. The connection of the section housings is flanged, the shafts are connected by a splined coupling. 2.3.2.2. Water protection To increase the performance of submersible electric motors great importance It has water protection. The hydraulic protection consists of a protector and a compensator and performs the following functions: · equalizes the pressure in the internal cavity of the engine with the pressure of the formation fluid in the well; · compensates for thermal changes in oil volume in the internal cavity of the engine and its leakage through leaky structural elements; · protects the internal cavity of the engine from formation fluid and prevents oil leakage when transmitting rotation from the electric motor to the pump. Exist various designs water protection Let's consider one of them, often found in fisheries. The compensator MK 51 (Fig. 2.17) is a housing 1 in the form of a pipe, inside of which there is a rubber diaphragm 2. The internal cavity of the diaphragm is filled with oil and communicates with the internal cavity of the electric motor through a channel in the head 3, which is blocked by a plastic plug 4. There is a hole in the head to fill the internal cavity of the diaphragm with oil, which is sealed with plug 5 on a lead gasket and a hole with bypass valve 6 and plug 7. The bypass valve is used in the process of preparing the compensator for installation. The cavity behind the diaphragm communicates with the formation fluid through holes in the compensator housing. The diaphragm ensures the transmission and equalization of formation fluid pressure in the engine mounting area with the oil pressure in the engine, and by changing its volume it compensates for thermal changes in the volume of oil in the engine during its operation. Studs are screwed into the head of the compensator for connection to the electric motor. During transportation and storage, the compensator is closed with lid 8. The MP 51 protector (Fig. 2.18) consists of a housing 1, inside of which there is a diaphragm 2 mounted on a support 3, two nipples 4 and 5, between which there is a heel assembly 6, an upper 7 and a lower 8 heads and a shaft 9 with two mechanical seals 10. The shaft rotates in bearings installed in the nipples and in the lower head. The lower end of the shaft is connected to the electric motor shaft, the upper end is connected to the pump shaft when installed in a well. The heel assembly absorbs axial loads acting on the shaft. The internal cavity of the diaphragm communicates with the internal cavity of the electric motor and is filled with oil when installing the motor. This oil serves as a reserve to compensate for its natural flow through the lower mechanical seal, which seals the rotating shaft. The cavity behind the diaphragm communicates with the cavity of the heel assembly and is also filled with oil to compensate for its flow through the upper mechanical seal. To remove air when filling the tread cavities with oil, there are holes in the nipples that are hermetically sealed with plugs 13 and 14 with lead gaskets. Nipple 4 has three holes through which formation fluid passes during operation of the unit, washes out solid particles from the area of ​​the upper mechanical seal and cools it. For the period of transportation and storage, the holes are closed with plastic plugs 11, which are removed before lowering the protector into the well. Rice. 3.17. Compensator Rice. 2.18. Tread The lower head of the protector has a flange and a seating collar with rubber rings 15 to seal the connection with the electric motor. Studs are screwed into the upper head for connection to the pump. During transportation and storage, the protector is closed with covers 16 and 17. There are also hydraulic protection designs that provide increased reliability of protecting the electric motor from formation fluid entering it. Thus, the MK 52 compensator has a useful oil volume that is twice as large as the MK 51 compensator, and the MP 52 protector has duplicated elastic diaphragms and three sequentially installed mechanical seals. When the ESP unit operates, during the process of turning the electric motor on and off, the oil filling it is periodically heated and cooled, changing accordingly in volume. Changes in oil volume are compensated by deformation of the elastic diaphragms of the compensator and protector. The penetration of formation fluid into the engine is prevented by the mechanical seals of the tread. 2.3.2.3. cable line To supply alternating current to the submersible electric motor, a cable line is used, consisting of a main power cable (round or flat) and a flat extension cable with a cable entry coupling. The connection of the main cable with the extension cable is ensured by a one-piece connecting splice. The extension cable running along the pump has reduced external dimensions compared to the main cable. The designs of the most common domestic cables KPBK (cable with polyethylene insulation, armored round) and KPBP (cable with polyethylene insulation, armored flat) are presented in Fig. 2.19, where 1 is a single-wire copper core; 2 - the first layer of high-density polyethylene insulation; 3 - second layer of high-density polyethylene insulation; 4 - a pillow made of rubberized fabric or equivalent substitute materials (for example, from a composition of high and low density polyethylenes); 5 - armor made of galvanized steel tape with an S-shaped profile (for the KPBK cable) or a stepped profile (for the KBPB cable). There are also special heat-resistant cables with insulation made of polyimide-fluoroplastic film and fluoropolymer, with lead sheaths over the core insulation, etc. Rice. 2.19. Cable designs KPBK (a) and KBPBP (b) 2.3.3. Pump check and bleed valves The pump check valve (Fig. 2.20) is designed to prevent reverse rotation of the pump impellers under the influence of the liquid column in the pressure pipeline when the pump is stopped and to facilitate restarting the pump. A check valve is also used when testing a tubing string after lowering the unit into the well. The check valve consists of a body 1, on one side of which there is an internal conical thread for connecting the drain valve, and on the other side there is an external conical thread for screwing into the fishing head of the upper section of the pump. Inside the housing there is a rubberized seat 2, on which the plate 3 rests. The plate has the ability to move axially in the guide sleeve 4. Rice. 2. 20. Check valve Under the influence of the flow of pumped liquid, plate 3 rises, thereby opening the valve. When the pump stops, plate 3 is lowered onto seat 2 under the influence of the liquid column in the pressure pipeline, i.e. the valve closes. During transportation and storage, caps 5 and 6 are screwed onto the check valve. The drain valve is designed to drain liquid from the pressure pipeline (tubing string) when lifting the pump from the well. The drain valve (Fig. 2.21) contains a body 1, on one side of which there is an internal conical thread of the coupling for connection to the pump-compressor pipes, and on the other side there is an external conical thread for screwing into the check valve. A fitting 2 is screwed into the housing, which is sealed with a rubber ring 3. Before lifting the pump from the well, the end of the fitting, located in the internal cavity of the valve, is knocked down (broken off) with a special tool (for example, a crowbar thrown into the tubing), and the liquid is removed from the tubing string flows through the hole in the fitting into the annulus. During transportation and storage, the drain valve is closed with covers 4 and 5. Submersible asynchronous motors, depending on the power, are manufactured in one- and two-section types. Depending on the standard size, the electric motor is powered with voltage from 380 to 2300 V. The operating frequency of alternating current is 50 Hz. When using a frequency regulator, the engine can operate at a current frequency of 40 to 60 Hz. Synchronous speed of the engine shaft is 3000 rpm. The working direction of rotation of the shaft, when viewed from the side of the head, is clockwise. Rice. 2.21. Drain valve 2.4. Designation of ESP and ESP In Russia, designations for installations of submersible centrifugal pumps of the UETsNM5-125-1800 type are accepted. This is deciphered as follows: U – installation; E – drive from a submersible electric motor; C – centrifugal; N – pump; M – modular; 5 – pump group; 125 – supply in nominal mode, m 3 /day; 1800 – pressure at nominal mode, m. Domestic factories produce ESP units of groups 4, 5, 5A and 6. They differ in the size of the so-called diametrical dimension, determined by the formula: , where is the diameter of the pump body; Engine housing diameter; – height (thickness) of the flat cable; – thickness of the protruding part of the protective device for flat cable / 6 /. The diagram for determining the diametrical dimensions of a submersible pumping unit is presented in Fig. 2.22. Units of various groups are designed for the operation of wells with different internal diameters of production strings. The geometric parameters of various groups of installations and their components are presented in Table 4.1. It should be noted that installations of a smaller group are suitable for operation in wells of larger internal diameter; for example, ESP of group 5 can be used in wells with an internal diameter of 130 and 144.3 mm. Rice. 2.22. Cross section and definition diagram diametrical dimensions of the submersible pump unit Table 2.1 Dimensional parameters for various groups of ESP installations Indicators ESP Group Minimum internal diameter of production string, mm Pump outer diameter, mm External diameter of the motor, mm Diametrical dimension, mm The names of ESP groups originally denoted the nominal diameter of the well string in inches. At that time, units of groups 5 and 6 were being developed. However, production strings of wells of the same external diameter (for a nominal bore of 5 inches - 146 mm, for a nominal bore of 6 inches - 168 mm) can have different wall thicknesses and, as a result, different internal diameters. It subsequently turned out that approximately 90% of five-inch wells in the fields of the Soviet Union had an internal diameter of at least 130 mm. For these wells, pumps of a group conventionally called 5A were developed. Subsequently, additional gradations arose related to the configuration of ESPs of groups 5 and 6 with engines of various diameters. Therefore, within groups 5 and 6, there are currently two types of installations, slightly different from each other in diametrical dimensions (see Table 2.1). As for ESPs of group 4, the need for their development was associated not only with the presence of wells with an internal diameter of the production string of 112 mm, but also with the impossibility of complying with the requirements of the ESP operating manuals when extracting oil from highly curved five-inch wells. The permissible rate of increase in wellbore curvature should not exceed 2° per 10 meters, and in the area where the installation is operating, the change in curvature should not exceed three minutes per 10 meters. A significant number of wells drilled in the fields of Western Siberia in the 70-80s of the twentieth century do not meet these requirements. It is impossible to operate them in ways other than ESP. Therefore, oil workers had to deliberately violate the requirements of the instructions in order to extract products from such wells. Naturally, this had an extremely negative impact on the turnaround time of the wells. Small-sized installations (group 4) more easily pass through critical intervals of large curvature when lowering into wells. However, small-sized ESPs have longer lengths and lower efficiency values. The range of standard sizes of ESP units produced by the domestic industry is quite wide. In size 4, pumps are produced with a nominal flow from 50 to 200 m 3 /day and pressures from 500 to 2050 m, in size 5 - with a flow from 20 to 200 m 3 /day and pressures from 750 to 2000 m, in size 5A - with a flow from 160 to 500 m 3 /day and pressures from 500 to 1800 m, in size 6 - with a flow from 250 to 1250 m 3 /day and pressures from 600 to 1800 m. It should be noted that new pump sizes appear almost every year , created by machine builders at the request of oil industry workers, so that the specified list of ESP standard sizes can be supplemented. An example of a pump symbol structure is shown below. Submersible electric motors SED with an outer housing diameter of 103 mm have a power from 16 to 90 kW, with a diameter of 117 mm - from 12 to 140 kW, with a diameter of 123 mm - from 90 to 250 kW, with a diameter of 130 mm - from 180 to 360 kW. Submersible electric centrifugal pumps, like ESPs, have a symbol that may differ slightly for different manufacturers. Design options for ETsNA pumps manufactured according to TU 3631-025-21945400-97 are designated by numbers from 1 to 4: 1 – the pump includes an inlet module, the sections are connected by flange; 2 – the pump includes an input module, connecting sections of the “flange-housing” type; 3 – the pump includes a lower section with a receiving mesh, the sections are connected by flange; 4 – the pump contains a section with a receiving mesh, the sections are connected in the “flange-body” type. According to TU 3631-00217930-004-96 and TU 3631-007-00217930-97, pumps of three modifications are manufactured: · with a design identical to the pump according to TU 26-06-1485-96 (pumps are designated ETsNM(K)); · with the connection of sections according to the “flange-body” type (modification number L1); · with the connection of sections according to the “flange-housing” type, with intermediate bearings (modification number L2). 3. Equipment 3.1. Active keys The following keys are used for this lab: W, S, A, D – for moving in space; F2, E – analogues of the middle key of the manipulator (the first press takes an object, the next press places it); Ctrl – sit down; F10 – exit the program. Rice. 3.1. Active Keyboard Keys Rice. 3.2. Manipulator functions Left mouse button (1) - when pressed and held, one or another object is processed (rotated, switched). Middle key (2) - the first press (scrolling is not used) takes the object, the next time it is placed (attached). Right key (3) - a cursor-pointer appears (if repeated, it disappears). Note: When the cursor appears, it is impossible to look up and to the sides. 4. Work order The purpose of the laboratory work is to study the design of a submersible centrifugal pump. The ESP pump is placed on a rack. Only the units indicated in the captions to the figures can be disassembled. When removing a unit, an inscription appears at the top right indicating the removed unit. Rice. 3.3. Hydraulic protection of SEM (submersible electric motor) (all nodes are removed) 1 – PED hydraulic protection sub; 2 – hydraulic protection of motors; 3 – motor hydraulic protection housing Rice. 3.4. PED 1 – sub (removable); 2 – coupling (removable); 3 – shaft (removable); 4 - electrical cable supply (removable); 5 - submersible electric motor Rice. 3.5. Motor hydraulic protection (all components are removable) 1 – sub; 2 – hydraulic protection of motors; 3 – water protection housing Rice. 3.6. Lower axial support (all components are removable) 1 – sub; 2 – heel; 3 – upper support; 4 – sub; 5 – sub; 6 – lower support; 7 - axial support housing Rice. 3.7. Receiving grid (all nodes are removed) 1 – splined coupling; 2 – receiving section; 3 – shaft; 4 – radial shaft support; 5 - receiving grid (removable); 6 – radial shaft support; 7 – spline coupling Rice. 3.8. Pump section Rice. 3.9. Lower part of the pump (all components are removable) 1 – clamp; 2 - tubing pipe; 3 - check valve; 4 – sub; 5 – sub; 6 – radial bearing 5. Test questions 1. Purpose, scope and composition of the ESP. 2. List the main components of an ESP type pump. 3. Purpose and design of the stages that make up the pump? 4. List the design types of stages in the ESP. What are the advantages and disadvantages of various design solutions? 5. How are axial and radial loads perceived on the impeller? 6. Explain the concepts of “single-bearing” and “double-bearing” pump stage. 7. Explain the concept of “floating” type of impeller? 8. What types of impellers are used in ECPM, ECPMK? 9. How is the guide vane mounted in the pump section? 10. How is the axial and radial load perceived on the shaft of the pump module section? 11. What is the design feature of the hydrodynamic heel? 12. What is the difference between a modular submersible pump and a conventional one? 13. Purpose and design of the input module, head module? 14. Purpose of waterproofing and its composition? 15. What is the operating principle of the compensator? tread? 16. What is the purpose of a check valve? drain? 17. How does a check valve work? drain? 18. Symbol of ESP and ESP. 6. Literature 1. Bocharnikov V.F. Handbook of oil and gas equipment repairman: Volume 2 / V.F. Bocharnikov. - M.: “Infra-Engineering”, 2008. – 576 p. 2 Bukhalenko E.I. and others. Oilfield equipment: reference book / E.I. Bukhalenko et al. - M., 1990. - 559 p. 3 Drozdov A.N. Application of submersible pump-ejector systems for oil production: textbook. allowance. / A.N. Drozdov. – M.: Russian State University of Oil and Gas, 2001 4. Ivanovsky V.N., Darishchev V.I., Sabirov A.A. and others. Borehole pumping units for oil production / V.N. Ivanovsky, V.I. Darishchev, A.A. Sabirov and others - M.: State Unitary Enterprise Publishing House "Oil and Gas" Russian State University of Oil and Gas named after. THEM. Gubkina, 2002. – 824 p. 5. Installations of submersible centrifugal pumps for oil production. International translator / edited by V.Yu. Alikperova, V.Ya. Kershenbaum. - M., 1999. - 615 p. 7. Authors Laboratory work “Study of the design of a submersible centrifugal pump” in the discipline: “Oil and gas field equipment” Methodological support: Associate Professor, Ph.D. Bezus A.A. Associate Professor, Ph.D. Dvinin A.A. Assistant I.V. Panova Editor: Yakovlev O.V. 3D graphics: Elesin A.S. Script programming: Kazdykpaeva A.Zh.

I have long dreamed of writing on paper (printing on a computer) everything I know about ESPs.
I will try to tell you in simple and understandable language about the Electric Centrifugal Pump Installation - the main tool that produces 80% of all oil in Russia.

Somehow it turned out that I have been connected with them all my adult life. At the age of five he began traveling with his father to the wells. At ten he could repair any station himself, at twenty-four he became an engineer at the enterprise where they were repaired, at thirty he became deputy general director at the place where they are made. There is a ton of knowledge on the subject - I don’t mind sharing, especially since many, many people constantly ask me about this or that relating to my pumps. In general, so as not to repeat the same thing over and over again in different words- I’ll write it once, and then I’ll take the exams;). Yes! There will be slides... without slides there will be no way.

What it is.
ESP is an installation of an electric centrifugal pump, aka a rodless pump, aka ESP, aka those sticks and drums. ESP is exactly that (feminine)! Although it consists of them (masculine). This is a special thing with the help of which valiant oil workers (or rather service workers for oil workers) extract formation fluid from underground - this is what we call the mulyaka, which is then (after undergoing special processing) called with all sorts of interesting words like URALS or BRENT. This is a whole complex of equipment, to make which you need the knowledge of a metallurgist, metalworker, mechanic, electrician, electronics engineer, hydraulics, cable engineer, oil worker, and even a little gynecologist and proctologist. The thing is quite interesting and unusual, although it was invented many years ago and has not changed much since then. By and large, this is a regular pumping unit. What is unusual about it is that it is thin (the most common one is placed in a well with an internal diameter of 123 mm), long (there are installations 70 meters long) and works in such filthy conditions in which a more or less complex mechanism should not exist at all.

So, each ESP contains the following components:

ESP (electric centrifugal pump) is the main unit - all the others protect and provide it. The pump gets the most - but it does the main job - lifting the liquid - that's how its life is. The pump consists of sections, and the sections consist of stages. The more stages, the greater the pressure that the pump develops. The larger the stage itself, the greater the flow rate (the amount of liquid pumped per unit of time). The greater the flow rate and pressure, the more energy it consumes. Everything is interconnected. In addition to flow rate and pressure, pumps also differ in size and design - standard, wear-resistant, corrosion-resistant, wear-corrosion-resistant, very, very wear-corrosion-resistant.

SEM (submersible electric motor) The electric motor is the second main unit - it turns the pump - it consumes energy. This is an ordinary (electrically) asynchronous electric motor - only it is thin and long. The engine has two main parameters - power and size. And again, there are different versions: standard, heat-resistant, corrosion-resistant, especially heat-resistant, and generally indestructible (as if). The engine is filled with special oil, which, in addition to lubricating, also cools the engine and greatly compensates for the pressure exerted on the engine from the outside.

The protector (also called hydraulic protection) is a thing that stands between the pump and the engine - it, firstly, divides the engine cavity filled with oil from the pump cavity filled with formation fluid, while transmitting rotation, and secondly, it solves the problem of equalizing the pressure inside the engine and outside ( In general, there are up to 400 atm, which is about a third of the depth of the Mariana Trench). They come in different sizes and, again, all sorts of designs blah blah blah.

A cable is actually a cable. Copper, three-wire... It's also armored. Can you imagine? Armored cable! Of course, it will not withstand a shot even from a Makarov, but it will withstand five or six descents into the well and will work there for quite a long time.
Its armor is somewhat different, designed more for friction than for a sharp blow - but still. The cable comes in different sections (core diameters), differs in armor (regular galvanized or stainless steel), and it is also temperature resistant. There is a cable for 90, 120, 150, 200 and even 230 degrees. That is, it can operate indefinitely at a temperature twice as high as the boiling point of water (note - we are extracting something like oil, and it doesn’t burn very well - but you need a cable with a heat resistance of over 200 degrees - and almost everywhere).

Gas separator (or gas separator-dispersant, or just a dispersant, or a dual gas separator, or even a dual gas separator-dispersant). A thing that separates free gas from liquid... or rather liquid from free gas... in short, it reduces the amount of free gas at the inlet to the pump. Often, very often, the amount of free gas at the pump inlet is quite enough for the pump not to work - then they install some kind of gas-stabilizing device (I listed the names at the beginning of the paragraph). If there is no need to install a gas separator, they install an input module, but how should the liquid get into the pump? Here. They install something in any case.. Either a module or a gas engine.

TMS is a kind of tuning. Who deciphers it - thermomanometric system, telemetry... who knows how. That's right (this is an old name - from the shaggy 80s) - a thermomanometric system, we'll call it that - it almost completely explains the function of the device - it measures temperature and pressure - there - right below - practically in the underworld.

There are also protective devices. This is a check valve (the most common is KOSH - a ball check valve) - so that liquid does not drain from the pipes when the pump is stopped (raising a column of liquid through a standard pipe can take several hours - it’s a pity for this time). And when you need to raise the pump, this valve gets in the way - something is constantly pouring out of the pipes, polluting everything around. For these purposes, there is a knock-down (or drain) valve KS - a funny thing - which is broken every time when lifted from the well.

All this equipment hangs on pumping and compressor pipes (tubing - fences are made from them very often in oil cities). Hangs in the following sequence:
Along the tubing (2-3 kilometers) there is a cable, on top - the CS, then the KOSH, then the ESP, then the gas pump (or input module), then the protector, then the SEM, and even lower the TMS. The cable runs along the ESP, throttle and protector all the way to the engine head. Eka. Everything is a cut short. So - from the top of the ESP to the bottom of the TMS it can be 70 meters. and a shaft passes through these 70 meters, and it all rotates... and around there is high temperature, enormous pressure, a lot of mechanical impurities, a corrosive environment.. Poor pumps...

All things are sectional, sections no more than 9-10 meters long (otherwise how to put them in the well?) The installation is assembled directly at the well: PED, a cable, protector, gas, sections of a pump, valve, pipe are attached to it.. Yes! Don’t forget to attach the cable to everything using clamps (such special steel belts). All this is dipped into the well and works there for a long time (I hope). To power all this (and somehow control it), a step-up transformer (TMPT) and a control station are installed on the ground.

This is the kind of thing that is used to extract something that later turns into money (gasoline, diesel fuel, plastics and other crap).

Let's try to figure out how it all works, how it's done, how to choose and how to use it.

Like. ESP equipment consists of a submersible part, lowered into the well vertically on a tubing string, and a surface part connected to each other by a submersible power cable.

Encyclopedic YouTube

1 / 5

✪ Installation of ESP (ESP diagram) part 1

✪ Start-up of the ESP installation. Output to mode. Part 2

✪ ESP. Startup, switching to mode

✪ Operation of the ESP control station

✪ Sequence of actions when starting up and bringing into operation a well equipped with an ESP

Subtitles

Submersible equipment ESP

The submersible part of the ESP equipment is a pumping unit vertically lowered into the well on a tubing string consisting of a submersible motor (submersible electric motor), a hydraulic protection unit, a liquid receiving module, the ESP itself, a check valve, and a drain (drain) valve. The housings of all components of the submersible part of the ESP are pipes with flanged connections for mating with each other, with the exception of the check and drain valves, which are screwed to the tubing with threads. The assembled length of the submersible part can reach more than 50 meters. Part of the submersible equipment is also a submersible cable (KBPP), which is a flat armored three-core cable, its length directly depends on the depth of descent of the submersible part of the ESP.

ESP

An electric centrifugal pump for oil production is a multi-stage and, in general, multi-sectional design. The pump module section consists of a housing, a shaft, a package of stages (impellers and guide vanes), upper and lower radial bearings, an axial support, a head, and a base. The stage package with shaft, radial bearings and axial support are placed in the housing and clamped by the end parts. Pump designs differ in the materials of the working bodies, housing parts, friction pairs, design and number of radial bearings.

Major ESP manufacturers

Domestic manufacturers

Foreign manufacturers

Currently, the largest manufacturers of ESPs abroad are:

• REDA - USA
• Centrilift - USA
• ESP - USA

In recent years, ESP manufacturers from the People's Republic of China have also become more active.

ESP symbol structure

Today, with the development of new oil fields with complicated conditions for its production and the use of technologies that increase oil recovery from reservoirs in already exploited fields, it leads to a reduction in the overhaul period for the operation of traditional oil production equipment, including ESPs. This fact requires manufacturers to increase the range of equipment they produce, which can meet the conditions of specific wells. In this connection, new ESP models are being produced that have design features of the working bodies, their melting technology and the material from which they are made, the location of axial and radial supports and much more. All these features are reflected in the symbols of the pump model, which each manufacturer creates according to its own technical conditions, but all domestic manufacturers use a common form to indicate the standard size of the equipment in the model name.

Example of a symbol:

ESP 5-125-2150

• Electric centrifugal pump
• ESP size (conditionally indicates the minimum internal diameter of the casing in inches)
• Productivity - m³/day. (when the unit operates at an alternating current frequency of 50 Hz, rotation speed 2910 rpm, taking into account slip)
• Pressure - m (the sum of the pressures of all stages in all sections of the installation when operating at an alternating current frequency of 50 Hz is rounded to 50 meters)

Some manufacturers use the following designation ESP-5A-45-1800(3026), where in parentheses they indicate the speed at which the ESP must be operated to achieve the specified performance and pressure.

ESP manufacturers in the US use a different designation structure for their products, for example:

TD-650(242st) or DN-460(366st)

• The letter D indicates the series that determines the size of the pump housing.
• The next number indicates the ESP capacity measured in barrels. /day at AC frequency 60 Hz
• The number of operating stages in the pump is indicated in brackets

PED

In most cases, this is a specially designed motor and is an asynchronous, three-phase, two-pole AC motor with a squirrel-cage rotor. The engine is filled with low-viscosity oil, which performs the function of lubricating the rotor bearings and removing heat to the walls of the engine housing, washed by the flow of well products. SEDs are an ESP drive that converts electrical energy, which is supplied via a cable from above to the installation suspension area, into mechanical rotational energy of the pumps.

Water protection

Hydraulic protection is a device used to protect against formation fluid entering the cavity of the electric motor, to compensate for thermal expansion of the oil volume, and to transmit torque to the centrifugal pump shaft. The lower end of the shaft is connected to the shaft (rotor) of the electric motor, the upper end is connected to the pump shaft when installed in a well. Water protection performs the following functions:

• equalizes the pressure in the internal cavity of the engine with the pressure of the formation fluid in the well;
• compensates for thermal changes in the volume of oil in the internal cavity of the engine (excess oil is released through the valves into the annulus of the well);
• protects the internal cavity of the engine from formation fluid ingress and oil leakage (role of the oil seal)
• transmits torque to the shaft of a centrifugal pump.

Liquid intake module

The formation fluid enters the working stages of the ESP through the receiving holes in the lower part of the pumping unit; for this purpose, in some installations there are holes in the lower part of the lower section of the ESP, but in most cases all ESP installations are equipped with a separate fluid receiving unit, which is called the receiving or input module. The shaft of the receiving module, using splined couplings, is connected from below to the hydraulic protection shaft, and from the top to the shaft of the lower section of the ESP, thus, during operation of the ESP, the rotation of the engine rotor-shaft and hydraulic protection is transmitted through this unit to the pump sections. In addition to receiving formation fluid and transmitting rotation, this unit, depending on the design, can filter formation fluid from mechanical impurities and act as a gas-stabilizing unit. In accordance with the above functions, the following groups of liquid receiving units can be distinguished:

Receiving module

The simplest unit listed below, its main tasks are to receive formation fluid into the pump cavity and transmit torque from the motor to the ESP. It consists of a base (1) with holes for the passage of formation fluid and a shaft (2), the holes are closed with a receiving mesh (3), which prevents them from clogging. As a rule, the length of the receiving module does not exceed 500 mm, and the diameter of the housing corresponds to the diameter of the housing of the pump sections and, like the ESP, is classified by size. When installing an ESP into a well, the receiving module is installed between the hydraulic protection protector and the lower section of the ESP or the gas-stabilizing unit if it is made without receiving holes; for this purpose, in the lower part of the base there is a flange with through holes for connection to the protector body, and in the upper end there are blind holes with threads into which the studs are screwed for connection to the flange of the unit mounted after the receiving module.

Submersible filter

A device that reduces the influence of mechanical impurities on the operation of an ESP. It can be presented as a module installed between the hydraulic protection protector and the lower section of the ESP where the entire filtering surface of the device is the area for receiving formation fluid. In this case, the submersible filter has in its design a shaft that transmits the rotation of the engine rotor to the pump sections and, in addition to filtering the formation fluid, performs the same functions as and a receiving module. The submersible filter can also be a module suspended below the entire installation. In this case, the filter is not a liquid receiving module but is an additional hanging equipment.

Gas separator

A device operating at the pump intake that reduces the negative impact of the gas factor by separating the gas phase from the produced formation fluid. The formation fluid through the receiving holes enters a rotating auger, which accelerates its movement, then passes through an impeller, “shaking” the liquid for degassing, into a separation drum in which, under the influence of centrifugal forces, heavier phases (liquid and mechanical impurities) are thrown to the periphery where through a special the channel moves to the pump stage, and more light gas the phase is consolidated in the center of the drum and is discharged through a special channel into the annulus of the well. The gas separator in the ESP is installed in place of the input module and consists of:

• housing (pipe of the same diameter as the ESP housing, 0.5-1 m long);
• shaft (receiving rotation of the engine rotor and transmitting rotation to the ESP shafts),
• lower base with a flange for connection with the water protection protector head, friction bearing and intake holes,
• upper base with friction bearing and outlet holes,
• auger,
• impeller,
• separator.

The gas separator allows the pump to operate stably when the gas content in the extracted mixture at the intake is up to 55%.

Gas dispersant

Just like a gas separator, it is a device that reduces the harmful influence of the gas factor on the operation of an ESP, but unlike a gas separator, it does not separate into liquid and gas phases, but rather mixes the released gas from the liquid into a homogeneous emulsion, while the gas is not discharged into the annulus .

Externally, these units are similar, except for the absence of holes for gas outlet in the gas dispersant, and inside it, instead of a separator, it has a set of working elements that whip up the production mixture.