RU2302681C1 - Electric cable - Google Patents

Abstract

FIELD: cable engineering; cables for feeding submersible oil-extraction pump motors and other submersible units.

SUBSTANCE: proposed electric cable designed for use at depths exceeding 2000 m has cylindrical insulated current-carrying conductors disposed in same plane, sheath, and armor of shaped steel band; its three conductors are tightly fitted through their insulation to one another throughout their entire length and covered with their common sheath to form wedges of sheath material in-between; thickness of common sheath on flat sides ranges between 0.7 and 1.0 mm and on lateral sides, between 1.0 and 1.5 mm. This cable is characterized in that it retains its insulation integrity upon pre-connection splicing and during lifting-and-lowering operations in sloping wells, its intermediate conductor is not crushed at points of contact with two lateral conductors when used at high temperatures.

EFFECT: enhanced service life.

1 cl, 1 dwg

Description

The electric cable for powering the electric motors of submersible oil pumps refers to cable technology and can be used to power submersible electrical systems.

The downhole and other factors affect the performance of cables:

- penetration of gas under pressure into the internal volume of insulation, a decrease in the insulation density leads to an increase in leakage currents - a decrease in the dielectric properties of the insulation;

- inappropriate high-speed rise of electric drive centrifugal pump (ESP) installations in the presence of gas in the insulation leads to a decrease in the insulation density, radial microcracks (microcracks) of the insulation, to an increase in leakage currents - to a decrease in the dielectric properties of the insulation;

- the presence of hot water above 80 ° C and its introduction into the insulation promotes the connection of the hydroxyl group (OH) with the molecular structure of the insulation, leads to a decrease in the dielectric properties of the insulation - an increase in leakage currents;

- leaching of ingredients from the insulation (special additives that increase the life of the cable) leads to a decrease in the dielectric properties of the insulation;

- the introduction of oily liquids of a non-dielectric nature under pressure into the insulation leads to a decrease in the density of the insulating material and an increase in leakage currents; shorten cable life;

- the introduction of oily liquids under pressure into the insulation, in a closed volume under the armor cover, leads to an increase in the insulation volume of the three cores, to squeezing the middle core and thinning its side walls, the result of this effect is the appearance of longitudinal cracks on the sides of the middle core and an increase in leakage currents;

- the introduction of chemicals into the insulation volume, such as NaCl, H ₂ S, hydrocarbon compounds and others, leads to a chemical compound with a molecular structure of insulation and an increase in leakage currents;

- high pressure negatively affects the operation of the insulation.

Known technical solution "Cable for submersible pumps" according to patent SU 1742863, IPC 5 Н01В 7/18, from 1990.01.15, publ. 1992.06.23, where a cable containing insulated conductors located in the same plane with filling between them, the filling being made in the form of gaskets of insulation material with longitudinal grooves adjacent to the insulation surface, and the gaskets and grooves are located symmetrically with respect to the plane passing through centers of insulated cores, and the thickness of the gaskets is less than their diameter.

The design is quite well disassembled during cable cutting and splicing, but the laid separate gaskets between the insulation cores in this design do not perform the function of protecting the insulation from compressive forces during hoisting operations of the oil-immersed cable and operation at temperatures up to 100 ° C in the well.

This technical solution allows to reduce the deformation of insulation by reducing the impact of the side insulated conductors on the middle core (when expanding its volume) in an enclosed space, in the region of the minimum thickness of the strip, but this does not protect the insulation itself from the introduction of extraneous materials mentioned above, which reduce the dielectric properties of the insulation .

The famous "Electric cable" according to the author's certificate of the USSR No. 1695399, IPC 7 Н01В 7/00, Н01В 7/08, dated 1989.07.04, publ. 1991.11.30 for powering the electric motors of submersible oil pumps, containing three insulated cores with shells of diameter D, one of which is located between the other two, a pillow for armor and general armor made of steel profiled tape, while the inner surface of the pillow is made with a rectangular protrusion located under said residential, wherein the height of the protrusion is (0.05-0.07) D, and the width is (0.70-0.95) D; the protrusion is formed by laying in one piece with a pillow under the armor.

However, this does not save the insulation of the middle core from being squeezed by two side wires. The impact of the side veins still occurs, only not in a straight line, but at an angle. Thinning occurs thinning longitudinally along the middle core, its cracking and reduction of service life.

The closest in technical essence is the “KPOBP cable” according to TU 16-505-129-82 VNIIKP, p. 4, fig. 1, 3, (adj. 1) with copper conductors, with polyethylene insulation - the first insulation layer, the second layer insulation, with a common shell made of polyethylene, armored, flat. The proposed common shell reliably protects the insulation geometry of the conductive conductors when it is in the borehole fluid at a temperature of 70-90 ° C.

When preparing the cable for operation, when cutting the cable and splicing, the insulation between adjacent conductors is usually damaged, its dielectric properties deteriorate. Because of this, during the operation of the cable, at an early stage, increased leakage currents and then an electrical breakdown of insulation are observed.

The objective of the proposed technical solution is to increase the service life of the cable at depths of more than 2000 meters, preserve the integrity of the insulation after cutting for connection and during tripping operations in deviated wells, preserve the medium core from crushing insulation in contact with the other two side conductors during operation at elevated temperatures.

The problem is solved due to the fact that the electric cable for powering the electric motors of submersible oil pumps contains cylindrical, located in the same plane, insulated conductive conductors, a sheath and armor made of steel profiled tape, while three conductors are tightly pressed with their insulation to each other along the entire length and covered with a common shell, with the formation of wedges from the shell material between them; the common shell on the flat sides is made with a thickness in the range of 0.7-1.0 mm, and on the sides - 1.0-1.5 mm.

The location in the same plane of cylindrical, insulated conductive cores, tightly pressed with their insulation to each other along the entire length, forms wedge-shaped spaces between the insulation of the cores, in which, when coated with a sheathing material, wedge-shaped inserts of sheathing material are formed, united by a thin girdle of the same material, for maintaining the geometry of the middle core when the cable is heated to a critical temperature.

The metal armor located around the sheath, when operating the cable at a temperature above a certain value, at which any insulating material increases in volume, exerts a compressive effect on the wedges through the sheath, which reliably maintain the geometry of the cores and prevent the lateral veins under the influence of the armor cover to exert a compressive insulation force middle vein.

The shell thickness along the plane was chosen optimal, with a thickness in the range of 0.7-1.0 mm, and sufficient to create a strong monolith with wedges and holding them in the right place, taking into account the compression of the armor cover made by winding over the common shell. On the sides, the shell has a sufficient thickness of 1.0-1.5 mm, and also saves the main insulation from the highest pressure of the armor cover during the technological operation of coating the shell.

This design is reliable, and also makes it easy to cut the cable without much difficulty. It is enough to make longitudinal cuts on the sides of the shell, the shell is easily diverted from the insulation of the cores in different directions. It is cut across the cable and removed without damaging the insulation.

The combination of features is new and leads to a technical result consisting in increasing the service life when operating the cable at depths of more than 2000 meters, maintaining the integrity of the insulation during tripping operations in deviated wells, and preserving from crushing the insulation of the middle core in contact with the other two side conductors when work in conditions of elevated temperatures.

The drawing shows an electric cable for powering the electric motors of submersible oil pumps, where conductive conductors 1, insulation layers 2 conductors, common casing 3, pillow 4, wedges 5, armor cover 6.

The electric cable for powering the electric motors of submersible oil pumps is made as follows.

Three insulated cores 1, tightly pressed with their insulation 2 to each other along the entire length, laid parallel in one plane using a special device, are covered with a common sheath 3, which creates a monolithic whole with formed longitudinal wedges 5 between insulated cores from the sheath material between them and the common the girdle connecting these wedges. To prevent geometry violations when covering 6 insulated cores with 1 armored coat, 1 common casing 3 is made on flat sides with a thickness in the range of 0.7-1.0 mm, and on the sides - 1.0-1.5 mm. On top of these layers place a pillow 4 of non-woven, needle-punched material and armor cover 6.

Claims (1)

An electric cable for powering the electric motors of submersible oil pumps, comprising cylindrical insulated conductive conductors located in the same plane, a sheath and armor made of steel profiled tape, characterized in that the three conductors are pressed tightly by their insulation to each other along the entire length and covered with a common sheath to form wedges of shell material between them; the common shell on the flat sides is made with a thickness of 0.7-1.0 mm, and on the sides - 1.0-1.5 mm.