RU2588608C1 - High-temperature coupling of cable input for submersible motor - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention can be applied to cable inlet design for tight connection of cable line to submersible electric motors for oil production. Cable input coupling comprises casing and shank of variable cross section filled with compound, connected to each other and fixed by means of sealing elements and rings on end of current-conducting cable. Each cable wire is passed through holes in casing, partly stripped from lead protective sheath along its length, and connected to plug tip mounted into block of plug tips. At end side of housing faced to shank, around through holes, projections are composed as sleeves with conical section at their ends.

EFFECT: higher reliability and longer service life of coupling due to excluded possibility of penetration liquid, washing outer surface of lead sheath, to external surface of insulating layer of current-conducting cable wire.

5 cl, 5 dwg

Description

The invention relates to the field of electrical engineering, in particular to end connectors for cables in a liquid medium, and can be used in cable entries for hermetically connecting a cable line to submersible motors designed to drive submersible pumps used in the oil industry for oil production.

A fairly large number of cable glands for a submersible motor cable entry are known, described in the technical literature [see, for example, International translator “Installations of submersible centrifugal pumps for oil production” - M .: Oil and gas, 1999. P. 410-412], in patents for the invention: RU 2251185 C2 of 10.16.2002; RU 2264681 C2 dated 11/14/2003; RU 23192668 C2 dated December 20, 2004; US 2012/0100737 A1, 04/26/2012.

All of these couplings contain a housing that is secured to the end of the cable with sealing elements or filled with a sealing compound. Inside the housing are the ends of the insulated cable wires, freed from the lead sheath, connected to the plug lugs brought out through the holes on the block of the plug lugs. To mechanically hold the cable from axial movement and additional protection against the effects of liquid, the inner tail of the sleeve is filled with a sealing compound or soldering is applied at the junction of the metal body, the shank and the cable armor.

However, during operation, when high temperatures are reached, followed by cooling to the reservoir temperature, the tightness of such couplings may be impaired, which will lead to the penetration of the well fluid to the outer surface of the insulating layer of the cable core, freed from the lead sheath.

The reason is the thermal stresses arising in the sealing elements installed on the outer or end surface of the lead sheath of the cable due to the high difference in the coefficients of thermal expansion of steel, rubber and polymeric materials.

The closest technical solution for the totality of features to the claimed is a high-temperature cable entry coupling for a submersible electric motor company Schlumberger Technology Corporation [US patent No. 8398420, publ. 03/19/2013], which contains a metal housing with a shank of variable cross section, interconnected by screws and fastened with sealing elements to the end of the conductive cable, each conductive wire of which is released to its length from the lead protective sheath and connected to a plug-in terminal mounted into the terminal block. The inner cavity of the shank on the cable entry side is filled with a sealing compound; before entering the housing, the lead sheaths of the cable wires are sealed with solder joints. In this design, the tightness of the connection of the ends of the cable wires freed from the lead sheath with the plug lugs is ensured by the sealing joints around each wire in the form of spring blocks and elastomeric conical elements.

The disadvantages of such a sealing connection are: the complexity of the design and the use of one compression disk, which with the help of a nut and three intermediate spring blocks creates an uneven clamping force of three rings and three elastomeric conical elements. In addition, the applied technological process of soldering two heterogeneous materials - lead and stainless steel - requires qualified specialists, while it is difficult to control at the place of the soldered seam and the structure of the material of the insulating layer cannot be controlled, and due to local heating of the cable insulation layer under the lead sheath in the soldering process may violate the integrity of the insulation (latent defect), which during operation can lead to electrical breakdown.

Complete filling of the inner cavity of the shank with a sealing compound for mechanical cable retention causes a mechanical violation of the integrity of the insulating layer of the wire in the form of microcracks when the temperature reaches above 250 ° C, because due to the large difference in the KTP of the steel and polymer materials and the increase in the volume of the compound, the wire is compressed and tends to exit from an enclosed space in the axial direction relative to the internal cavity.

The noted disadvantages reduce the reliability and service life of the cable entry coupling of the submersible motor.

The technical result achieved by the implementation of the invention is:

1) simplicity of design,

2) increasing reliability by eliminating the possibility of penetration of liquid washing the outer surface of the lead sheath to the outer surface of the insulating layer of the conductive cable core;

3) increasing the service life of the cable entry coupling at high temperatures up to 315 ° C (600 degrees Fahrenheit), high hydrostatic pressure up to 45 MPa, chemically aggressive formation fluid;

4) high maintainability.

The specified technical result is achieved by the fact that in a high-temperature cable entry coupling of a submersible electric motor, comprising a housing and a shank of variable cross section filled with a compound, interconnected and secured with sealing elements and rings at the end of the conductive cable, each wire of which is passed through through holes in the housing , freed for part of its length from a lead protective sheath, sealed at the entrance to the housing and connected to the plug tip, mounted According to the invention, protrusions in the form of bushings with a conical (conical) section at the end are made around the through holes on the end side of the housing of the plug tips according to the invention, the lead sheath separated from the wire is hermetically placed on the outer surface of the protrusions until it touches the end surface housing and education around (around the perimeter) of the base of the sleeve of the sealing ring with conical walls and secured with a crimp sleeve, repeating the configuration of the protrusion and having on the end face is in contact with the sealing ring, the crimp bushings of all the wires are fixed in the common clamping stop, while each wire is equipped with an insulator buried in the terminal block, and the inner cavity of the shank is filled with a compound at the input and output of the cable with the formation of layers separated from each other another fibrous separation material, and the thickness of the compound layer at the outlet is at least 1/5 of the length of the shank.

It is advisable to use mineral wool as a separation material. To ensure operation at high temperatures, it is preferable to manufacture insulators and a ceramic plug.

In addition, synthetic dielectric high-temperature grease with high hydrophobicity is added to the contacting surfaces of the coupling parts for additional protection against liquid penetration.

The invention is illustrated by drawings, where in FIG. 1 shows a longitudinal section of the proposed cable entry sleeve; in FIG. 2 is a transverse section of the coupling, view AA; FIG. one; in FIG. 3 is a longitudinal section of the sealing site of the lead sheath; in FIG. 4 is an exploded view of the coupling components; in FIG. 5 is a view of a cable wire before assembly.

The high-temperature cable entry coupling for the submersible motor (Fig. 1) contains a metal housing 1 and a metal shank 2 of variable cross section, mounted on the end of the cable 10 and interconnected by screws 9 (Fig. 4). The cable 10 is disconnected into its constituent three wires 6, covered with a lead sheath 5 and an insulating sheath 11 (Fig. 3, 5). On the end side of the housing 1 around the through holes designed to pass the cable wires 6, protrusions 20 are made from the side of the shank 2 in the form of bushings with a tapering conical section at the open end (Fig. 3). The ends of the wires 6, freed from the lead sheath 5 and partially freed from the insulating shells 11, through the holes in the protrusions 20 are brought out into the internal cavity of the housing 1 and connected by a threaded connection to the plug lugs 14 inserted into the block of the plug lugs 7 made of ceramic. A ceramic insulator 8 is mounted on each conductive wire 6, fixed with a sealing ring 18 and fixed in the recesses of the housing 1 with a sealing ring 12. The insulators 8 are buried in the terminal block 7, fixed inside the housing 1 with a locking ring 13 (Fig. 1 )

Separated from the conductive wire 6, the lead sheath 5 is stretched on top of the protrusion 20 and forms a sealing ring 21 with an external conical wall around its base on the end surface of the housing 1 (Fig. 3). On top, the lead sheath 5 is mounted on the protrusion 20 by means of a crimp sleeve 4 mounted on it, repeating the configuration of the protrusion and having an inner chamfer in contact with the O-ring 21. The crimp sleeves 4 of all wires are built into the clamp 3, made in the form of an annular part, mounted on the inner wall of the shank 2 (Fig. 1). To seal the places of mechanical fastening of lead shells 5, the space between the end surface of the housing 1 and the pressure clamp 3 and around the crimp sleeve 4 is filled with a high-temperature compound 16. The cable 10 with armor 15 (Fig. 2) at the inlet of the shank 2 is also fixed using a high-temperature compound 16 , the depth of the layer of which is not less than 1/5 of the length of the shank 2 (Fig. 1). The inner cavity of the shank 2 between the layers of the high-temperature compound 16 at the inlet and outlet of the wires of the cable 10 is filled with a separation material 19, for example, mineral wool. At the end of the housing 1, on the side of the plug lugs 14, a ring 17 is put on, which serves as a seal when the coupling is connected to an electric motor. O-rings 12, 17 and 18 are made of a gas-oil-resistant rubber compound that can withstand temperatures up to 315 ° C (600 degrees Fahrenheit).

The Assembly of the high-temperature sleeve cable entry is as follows.

O-rings 12 and 18 are pre-installed on the insulators 8. The inner surface of the housing 1, the insulators 8, the terminal block 7 are lubricated with synthetic dielectric high-temperature grease, for example, Tomflon EP-300. The insulators 8 are inserted into the recesses made in the housing 1 and a socket block 7 is put on them, which is fixed with a retaining ring 13 (Fig. 4).

A shank 2 is put on the end of the cable 10 with the armor 15. Then, the cable 10 with the armor 15 is fixed in the device for assembling the cable box and the technological process of cutting the ends of the conductive wires of the cable 10 is carried out (Fig. 5). From the end of each conductive wire 6, the lead sheath 5 and the insulating sheath 11 are removed and a thread is cut on the freed end of the copper core 22. The ends of the prepared conductive wires 6 are passed through the holes of the pressure clamp 3. The lead sleeve 5 is put on the lead sheath 5 of each wire 6, after which forming conductive wires 6 for assembly. To do this, using a special device, the lead sheath 5 is expanded, separating it from the insulating sheath 11. The ends of the conductive wires 6 thus prepared are passed through the holes in the protrusions 20 of the pre-assembled housing 1 so that the extended sections of the lead sheaths 5 extend over the protrusions 20 until they touch the end surface of the housing 1, and the conductive wires 6 through the insulators 8 installed in the housing 1 fell into the block of the plug lugs 7.

The housing 1 and the cable with armor 15 are fixed in the device for assembling cable sleeves. The pressure stop 3 is put on the compression sleeves 4, then the shank 2 is moved along the cable 10 with armor 15 towards the housing 1. During the movement, the pressure stop 3 is fixed in the recesses of the shank 2, and the compression sleeves 4 fit snugly onto the lead sheaths 5 worn on the tabs 20 with a similar configuration, and, sealing the lead, move it to the base of the protrusions 20, as a result of which between the chamfer of the sleeve 4 and the end surface of the housing 1, a tight conical shape of the lead ring 21 is formed, blocking the access of liquid and inside the body. When combining the end surfaces of the shank 2 and the housing 1, they are connected using screws 9 inserted into the housing 1. During this operation, the process of forming a mechanical tight connection of the lead sheath 5 of the conductive wire 6 with the housing 1 is monitored and checked for leaks.

On the threaded ends of the copper conductors 22, which are in the holes of the terminal block 7, screw the cable ends 14. When screwing in, part of the synthetic dielectric high-temperature grease is removed and air is not guaranteed in the internal cavity of the housing 1.

Then fill (Fig. 1) the inner cavity of the shank 2 with a high-temperature compound 16, for example, Thermoset EL-636 Erohu Encapsulant. Initially, a portion of the compound 16 is poured through the holes in the vertically located coupling through the holes in the pressure stop 3, which fills the gaps formed between the ends of the housing 1, the shank 2 and the pressure stop 3, and also completely envelops the compression sleeve 4 with the overlap of its end. They withstand the time for curing the compound, densely fill part of the cavity of the shank 2 with mineral wool 19 and the remaining part with a length of 1/5 of the length of the shank is filled with the compound flush with the end of the shank 2.

The formation of a sealed lead seal at the point of transition from lead to steel increases the reliability and safety of the coupling by eliminating the possibility of liquid penetrating the outer surface of the lead sheath to the outer surface of the insulating layer of the conductive wire.

Due to the greater difference in the KTR value of lead in relation to the KTP of steel during heating, the lead volume in the confined space increases and, as a result, an additional seal in the annular space of the transition from lead to steel. When cooled, the annular space of the transition of lead to steel remains constantly tight.

The conical shape of the lead seal allows you to maintain the tightness of this compound during prolonged use under conditions of reaching a maximum temperature of 315 ° C, followed by cooling to a minimum temperature of the reservoir fluid (thermal cycling mode).

High maintainability of the coupling is achieved due to the possibility of reuse of the parts included in it, the exception is only crimp bushings.

The proposed high-temperature cable entry sleeve can be used when operating in high-temperature environments, such as steam-coupled (SAGD) environments for gravity drainage of wells, in order to increase hydrocarbon production, as well as when operating electric centrifugal installations in a batch mode (operation with subsequent shutdown at inflow), in high-temperature wells with a significant temperature difference.

Claims (5)

1. A high-temperature cable entry sleeve for a submersible electric motor, comprising a housing and a compound-filled shank of variable cross section, interconnected and secured with sealing elements and rings at the end of the conductive cable, each wire of which is passed through the through holes in the housing, is released to its length from a lead protective sheath, sealed at the entrance to the housing and connected to a plug tip mounted in a block of plug tips, distinguishing I mean that on the end side of the housing facing the shank, around the through holes there are protrusions in the form of bushings with a conical section at the end, the lead sheath separated from the wire is stretched onto the outer surface of the protrusions until it touches the end surface of the housing to form a sealing sleeve around the base rings with conical walls and secured with a crimp sleeve, repeating the configuration of the protrusion and having a chamfer at the end in contact with the sealing ring, crimp bushings of all wires fixed in the general clamping stop, with an insulator buried in the terminal block on each wire, and the inner cavity of the shank filled with a compound at the input and output of the cable with the formation of layers separated from each other by a fibrous separation material, and the thickness of the compound layer at the output is not less than 1/5 of the length of the shank. 2. The coupling according to claim 1, characterized in that mineral wool is used as a release agent. 3. The coupling according to claim 1, characterized in that the insulators and the terminal block are made of ceramic. 4. The coupling according to claim 1, characterized in that a synthetic dielectric high-temperature grease with high hydrophobicity is applied to the contacting surfaces. 5. The coupling according to claim 1, characterized in that the o-rings are made of a gas-oil-resistant rubber compound that can withstand temperatures up to 315 ° C.

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