RU2449452C2 - Cooling system for asynchronous machine of vetohin for oil-and-gas wells (amv ogw) - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: asynchronous machine (AMV OGW) contains housing (1) where multipack stator (2) with winding (3) is accommodated, on shaft (5) made of 20X13 steel, multipack rotor (6) with screw-groove multistart thread is mounted for strata water pumping via non-magnetic operating clearance (10). To equalise temperatures throughout the machine the inlet of cold and the outlet of heated strata water is executed through alternating by length symmetrical groups oh holes in the housing (14-16) and (17-18), shifted by angle β/2 relative to each other, and the holes along cross-section radius are shifted by angle β in each group. Flow of strata water via three hemispheric channels (21) between stator and housing, shifted by 120° equalises temperature along stator length.

EFFECT: creation of effective system of cooling with surrounding strata water for internal active parts of multipack electric machines of vertical open configuration for oil-and-gas wells.

2 cl, 3 dwg

Description

The invention relates to the field of electrical engineering, in particular to submersible electric machines, which are used for drives of various underwater mechanisms of drilling and production facilities in the development and production of minerals and mineral resources of oil and gas on the seabed, as well as for drives of downhole pumps and drilling mechanisms in exploration and industrial development of the offshore continental shelf for oil and gas.

Scientific and technological progress and prospects for the development of intensive development of the extraction of mineral resources on the continent and on the continental shelf, the development of new oil and gas fields in the Siberian energy region of Tyumen, Orenburg, etc. and in connection with an increase in the depth of oil deposits to 3000 m, a lot of technical means are required and operating mechanisms that must be driven by highly reliable submersible electric motors (SEMs). To date, sealed oil-filled PEMs with a rather complex multi-stage hydraulic protection installed on the drive shaft side have been used to drive oil well pumps and drilling rigs. When it is bent and formation water enters the engine cavity, it fails due to corrosion of the active parts and a decrease in the insulation resistance of the stator winding. PED is cooled by reservoir fluid through the housing.

Known hermetic submersible electric motors of various designs and designs, operating in oil wells with submersion up to 1500 m with a temperature of surrounding formation water of 80 ° C, the cavities of which are filled with a liquid dielectric (for example, transformer oil or kerosene), used as an insulator and as a substance for balancing backpressure immersion depths (see submersible electric motors for pumps and electric drills of the Kharkov Electromechanical Plant (KhEMZ) and Special Design and Engineering technologically Bureau of submersible electrical equipment for drilling and oil production "Potential" (SKTBPE "Potential"), Kharkov, GOST 18058-80). For pumps of oil wells with immersion to a depth of 3000 m, the company "ALNAS" in Moscow developed a submersible electric motor of the type PEDS360-130MV5 when working in wells with formation fluid temperatures up to 150 ° C.

The main disadvantages of these PED are:

1. The cooling system of existing sealed PEMs designed to operate at a depth of 3000 m due to the high temperatures of the formation fluid medium reaching 150 ° C is not effective enough.

2. Hydroprotection of various designs of sealed SEMs has low operational reliability.

3. Sealing of PEM leads to a significant increase in the temperature of the stator winding to and above 200 ° C, which reduces the reliability of the winding wire and bearings.

4. Failures of hydraulic protection (depressurization of the compensating element, wear of seals, etc.) leads to the penetration of aggressive formation fluid into the cavity of the PED and its premature failure, mainly due to electrochemical corrosion.

In a well-known technical solution for A.S. No. 279769 designed a shielded type submersible motor containing a sleeve between the rotor and the stator, which seals the stator winding from overboard formation water, the shielded stator cavity is filled with a liquid dielectric (oil). The design is complex, in addition, the sleeve increases the losses from eddy currents.

Known submersible pumping unit vertical design as.with. No. 939830, which contains a stator, a rotor with a shaft installed in the bearings and bearing shields with holes for the inlet and outlet of the fluid. A pump is mounted on the rotor shaft, which drives the coolant through the lower holes in the housing through the gap between the rotor and the stator, as well as through the upper hole in the pump housing and supplies this fluid to the consumer. This pump unit is used in wells for pumping fresh water. When immersed in aggressive acidic water with pH <7, it will fail due to electrochemical corrosion of the active parts of the machine, bearings and windings of the stator and rotor.

Of the known devices, the closest to the claimed one selected for the prototype is the "Electric machine Vetokhin EMV" (see patent No. 2072609, BI No. 3, 01/27/97), which contains a stator, a rotor with a shaft mounted in bearings, a housing filled liquid cooler, and bearing shields with holes. Sea water was used as a cooler, and the holes in the bearing shields for water inlet and outlet are located in two groups. This machine provides reliable operation as the drive of any underwater mechanism located at an unlimited depth of immersion in sea water, and the openings in the shield provide reliable cooling of all active parts of EME. However, in this machine, the rotor diameter is comparable with its length and the length of the stator and the heating of all parts of the machine will be uniform, and the temperature of the winding will not exceed the temperature difference in the insulation of the winding wire plus the temperature of the surrounding sea water, i.e. not higher than 50 ° C. The disadvantage of this design of EMV for oil wells is the commensurability of the diameter and length of the large rotor for large machines of high power, which cannot be implemented in submersible motors for pumps and "Burov" mechanisms for oil and gas wells. PEMs for oil and gas wells have a small diameter of up to 150 mm, and lengths for large engine capacities reach 8 m, with hydraulic protection up to 16 m, in which the stators, rotors and hydraulic protection are multi-stage. In addition, with a well depth of up to 3000 m, the temperature of the surrounding acidic aggressive formation water reaches 150 ° C and therefore a cooling system like EMW cannot work efficiently and equalize the temperatures of the active parts inside the machine along the entire length.

The objective of the invention is to increase reliability, performance, increase service life and reduce weight and dimensions by half in the developed asynchronous machine (AMV NGS) taking into account the immersion depth of 3000 m and formation water temperature of 150 ° C through the use of a new hydraulic system of holes in the housing through which the input and output of the cooling surrounding formation water is carried out.

The problem is solved in that in the well-known vertical asynchronous submersible electric machine, comprising a stator with slots and a winding, a rotor-groove rotor, a shaft, bearings enclosed in a housing with holes for entering and leaving cooling formation water, in the housing along its length relative to the shaft axis there are groups of symmetrically arranged holes along the radial section for the entry of the surrounding formation fluid into the machine and the heated outlet from it, of which the first group is located in the lower part of the bearing assembly cooling of the sliding surfaces of the bearing, the second group is located on the side of the lower frontal parts, the third group is located in the water supply zone into the grooves of the stator winding, as well as to the channels between the housing and the stator packets and the non-magnetic gap, through which the groove thread on the rotor is driven through the gap, the fourth and the fifth group are designed to exit the heated water from the area of the upper frontal parts, grooves, non-magnetic working gap and channels between the housing and the stator packets, the sixth group of holes serves for feeding and water to the upper thrust bearing, and the seventh group - for heated water to exit the bearing area, in each group there are 3-6 holes with a diameter of 4-6 mm, evenly distributed around the circumference of the housing and radially shifted by the same angle, and each the group with respect to the other is shifted by half an angle, alternating between each other along the housing, the stator is multi-packet, and between the housing and the back of the stator packets there are three axial channels of hemispherical shape with a diameter of 3-5 mm, made in steel packets and shifted between battle at 120 °.

The invention is illustrated by drawings, in which:

- figure 1 shows the AMS NGS. Longitudinal section of a submersible asynchronous machine for pump drive;

- figure 2 shows a cross section of the housing in the plane of the section along the cooling holes;

- figure 3 shows a cross section of a stack of stator steel between the sheets.

According to the invention (FIG. 1, FIG. 2), an asynchronous machine (AMS NGS) comprises a housing 1, in which stator packages 2 with a long winding 3 from a winding wire with polyimide-fluoroplastic insulation, for example, PPI-U brand, are placed. The stator has a tread protection of the core package 2 in the form of rings 4 of a magnesium alloy, for example, grade ML4. A rotor 6 is mounted on a shaft 5 made of steel 20X13 with a multi-thread rotary groove and having a short-circuited winding and short-circuited rings 7 made of electrotechnical red copper. The stator immobility is ensured by its landing through the key on the housing and the groove under the key 8 in the stator package 2, Fig.3. The tread protection of the rotor is provided by bushings 9 made of magnesium alloy of the ML4 brand, pressed onto the free ends of the shaft 5 directly against the iron package of the rotor 6. Non-magnetic clearance 10 provides axial flow of produced water along the machine to cool the stator and rotor. The machine contains two thrust bearings: lower 12, the liner of which is pressed into the lower bearing shield 11; the upper bearing, the liner 13 of which is pressed into the machine body. Since the developed machine has a large length and multi-package stator and rotor, it is proposed to enter and exit water using hydraulic holes from seven groups alternating along the body to more effectively cool the inside of the machine and equalize the temperature along the entire length using surrounding formation water, figure 1: the first group (pos. 14) serves to enter water into the cavity of the lower bearing shield for cooling the sliding surfaces of the bearing; the second (pos. 15) and third (pos. 16) groups are designed to supply water from two sides to the frontal parts and grooves of the stator winding, as well as to the channels between the housing and stator packages and the non-magnetic working gap, through which the rotor-groove rotor drives it cooling formation water; the fourth group (pos. 17) and the fifth group (pos. 18) serve to exit the heated water from the frontal area of the stator winding, the grooves, the channel between the housing and the stator and the non-magnetic working gap for the housing into the external environment; the sixth group (pos. 19) serves to supply formation water for cooling the upper thrust bearing; the seventh group (pos. 20) is designed for the exit of heated water from the bearing area beyond the housing into the external environment. To achieve effective cooling and avoid oncoming water flows inside the machine, which depend on hydraulic losses of power, noise and vibration of the machine, the holes in the body are evenly distributed around the circle and radially shifted to the center of the section by the same angle β, figure 2, and each group in relation to the other is shifted by an angle β / 2, alternating among themselves along the body. In multi-pack stators and rotors, i.e. in long machines, the hydraulic resistance of all axial channels (grooves, non-magnetic clearance) will increase, which will slow down the flow of cooling formation water, therefore, to increase the flow of cooling water, and therefore to improve the cooling effect, it is proposed to create three axial channels between the housing and stator packages hemispherical shape in steel stator packets with a diameter of 3-5 mm, shifted in space by 120 °, Fig.3. The decrease in the outer surface of the stator packets will be no more than 4%.

The proposed electric machine (AMV NGS) when immersed in the formation of aggressive acidic water with a pH <7 works as follows. When the stator 2 is connected to the network, a rotating rotor-groove rotor 6 with a shaft 5 will create formation water mixing in the areas of the frontal parts and bearings inside the machine, a groove-groove cut on the rotor surface will pump it along the working gap 10 along the machine, i.e. turbulent rotation of water will turn into translational laminar motion. When the electric motor is heated during operation, heat from the active parts is removed as follows: cold formation water from the environment through the symmetrical holes 14 of the first group enters the sliding pair of the lower bearing 12, and through the openings 15 of the second group and the holes 16 of the third group enters the frontal parts of the winding 3, grooves, non-magnetic working gap 10, to the input of the channels 21 between the stator 2 with a rigid mount 8 and the housing 1, as well as to the rotor 6 and its short-circuited winding 7. Next, heated reservoir water from the grooves of the winding 3 s tator, channels 21 between the stator 2 and the housing 1, a non-magnetic gap 10 exits through the fourth group of holes 17, and out of the upper frontal parts through the fifth group of holes 18 enters the environment. To cool the upper thrust bearing, cold formation water enters from the external environment through the sixth group of holes 19 and heated water leaves the bearing area through the seventh group of holes 20. The stator is electrochemically protected from contact corrosion when it is in acidic formation water, like an electrolyte. using tread rings 4 of a magnesium alloy, for example, grade ML4, pressed into the housing close to the stator iron package on both sides, of the rotor by tread bushings 9 of the same alloy, apressovannymi against the packages become loose ends on the shaft 5 of the rotor 6 on both sides.

The claimed technical solution for the invention will allow:

1) the open design of a submersible electric motor for pumps and drilling mechanisms will reduce the weight of the engine by at least two times due to the exclusion from the design of multi-stage hydraulic protection, dielectric fluid and compensation system;

2) when drilling a well to a depth of 3000 m, at which the temperature of the surrounding formation water will be 150 ° C, the effective cooling of the internal active parts of the machine will be provided as much as possible with channels between the body and the stator and the proposed system of groups of symmetrical inlet and outlet openings along the length of the body , shifted along the radius of the cross section by the same angle, and the holes of the subsequent group - by half the angle with respect to the previous group in order to avoid the oncoming flows of the surrounding formation water, which ozvolit equalize and reduce the temperature in all zones inside the engine, which means enhance the reliability of the insulation system and the winding wire-thrust sliding bearings.

Claims (2)

1. An asynchronous submersible machine (AMV NGS) of vertical design, comprising a stator with slots and a winding, a rotor-groove rotor, a shaft, bearings enclosed in a housing with holes for the input and output of cooling formation water, characterized in that the housing along its length relative to the axis the shaft there are groups of symmetrically arranged holes along the radial section for the entry of the surrounding formation fluid into the machine and the heated outlet from it, of which the first group is located at the bottom of the bearing assembly in the sliding cooling zone bearing surfaces, the second group is located on the side of the lower frontal parts, the third group is located in the water supply zone into the grooves of the stator winding, as well as to the channels between the housing and the stator packets and the non-magnetic gap, through which the rotary groove on the rotor is driven through the gap, the fourth and the fifth group is intended for the exit of heated water from the area of the upper frontal parts, grooves, non-magnetic working gap and channels between the housing and the stator packets, the sixth group of holes serves to supply water to the upper a thrust bearing, and the seventh group - for heated water to exit the bearing area, each group has 3-6 holes with a diameter of 4-6 mm, evenly distributed around the circumference of the housing and shifted by the same angle in radius, and each group with respect to the other is shifted by half an angle, alternating among themselves along the body. 2. Asynchronous submersible machine (AMV NGS) of vertical design according to claim 1, characterized in that the stator is multi-packet and between the housing and the back of the stator packets there are three axial channels of hemispherical shape with a diameter of 3-5 mm, made in steel packets and shifted together 120 °.

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