RU22579U1 - PLANE HEATING CABLE FOR OIL WELL HEATING SYSTEM - Google Patents

Description

The utility model relates to cable technology, namely to the designs of heating cables used in the heating system of oil wells in oil production.

The heating system for oil wells is designed to prevent a decrease in oil production due to the deposition of paraffins and the formation of hydrates in the tubing of the installation used in the extraction of paraffin base oils by reducing their viscosity. The temperature in the formation is usually high enough to allow the flow of oil, however, when moving to the surface, the temperature decreases as heat is transferred to an increasingly colder surrounding rock. In some cases, the losses are large enough, which leads to thickening and deposition of paraffins on the walls of the tubing. The viscosity of the extracted paraffin base oils increases with decreasing temperature, which makes pumping difficult.

For most cases, these problems can be avoided by compensating for the heat loss of the surrounding rock at the top of the pump string, where the heat loss reaches its maximum by using a heating cable. Heating of the tubing is one of the most economical options

anti-paraffin deposits compared to other methods like,

for example, washing with hot oil, mechanical cleaning, pumping in chemical additives or steam and ensures a constant maximum flow rate of wells, reducing the cost of operating the latter.

Most intensively, paraffin is deposited on the inner surface of the lifting pipes of the wells. Numerous field studies have shown that the distribution pattern of paraffin deposits in the risers of different diameters is approximately the same. The thickness of the deposits gradually increases from the place of the onset of formation at a depth of 500 900 m and reaches a maximum thickness at a depth of 50 - 200 m from the mouth, then decreases by 1 - 2 mm in the area of the mouth 1.

To combat paraffin deposits in the late 90s, flat three-core heating cables 2 were created, laid on the outer surface of the tubing of oil production plants. The issues of heating the oil flow in the tubing of the well with the use of heating cable 3 are considered. The latter is attached to the pipe with belts and the heating of the pipe is ensured by the transfer of heat from the armor of the heating cable.

The temperature of the heating pipe depends on the size of the gap between its outer surface and the plane of the armor of the cable, as well as the width of the latter. In order to increase the heating temperature of the tubing without increasing the power consumed by the cable per unit length, modifications of flat heating cables of increased width 2M - / 3

rins. A DC cable with split conductors was developed (each core is made of two separately insulated conductors or with a filler between the wires); three-core, in which the increase in width is provided through the use of a filler placed between insulated conductive conductors, or the execution of one core of two insulated conductors. For steel armor, a steel tape with a relative elongation at break of at least 30% is adopted, which improves the flexibility of the heating cable and reduces the gap between the cable and the pipe.

The use of a flat cable of increased width, better flexibility allows to reduce the thermal resistance of heat transfer from the armor of the cable to the tubing, which is related to the size by the ratio:

GAYAD X a, ° Cm / W, where

A - the gap between the cable and the tubing, mm a - the width of the flat cable, mm

A, d - thermal conductivity of oil or gas, W / m x ° C.

The conductive cable core is made of galvanized steel wire or copper with an additional coating of electrical insulating varnish or by tinning. Additional coating of the wire provides better adhesion of polymer insulation to the surface of the first; protects the structure of the insulating material from destructive wagon /; G5s

A

the effects of copper ions, especially at elevated temperatures. For insulation of cables with a permissible core heating temperature of + 120 ° C, the use of a block copolymer of propylene with ethylene or a silica-crosslinked polyethylene or a block copolymer of propylene with ethylene and a silane-crosslinked polyethylene in any order is provided. The insulation is adopted as two-layer or single-layer.

Over the insulation surface, the imposition of a winding from a tape of fibrous or film material is provided in order to reduce mechanical stresses on the insulation when applying armor from steel tape and during cable operation. A cushion of tape material and general armor of steel tape with a relative elongation of at least 30% are imposed on coiled and parallel-laid cores.

The length of the cable line, the power consumed by the cable per unit length, the phase current and voltage for a three-core cable are related by the ratio:

l / w X C / „X / X cos (О L, km, where

RO - power consumed by a cable 1 km long, W;

cos f - power factor;

I is the phase current determined by the formula:

/, 1, A, where

4-M1P p

R is the ohmic resistance of the DC circuit at the operating temperature of the cable. Ohm / km.

Flat heating cable for the heating system for oil wells was used on a number of rod installations for oil production in the Perm region. When using heating systems containing a heating cable, washing of wells with hot oil is excluded for 12-15 months and operation continues. Before installing the cable, the number of flushing was 2-3 times a month. A three-fold increase in the overhaul period of wells was achieved. The economic effect was achieved by reducing the number of underground well repairs, increasing the inter-cliff period of the pump string of oil production units, and reducing the number of steams. Improved environmental protection for R - active resistance of one phase of the cable at operating temperature, Ohm / km; UH - linear voltage of a three-phase system, frequency 50 Hz, V For a constant voltage cable: t L L, km, where PO is the power consumed by a cable 1 km long, W; and - voltage. IN; The value of direct current is determined by the formula: / 1, A, where

by reducing oil spills during well operation and reducing the use of vehicles.

A general view of a flat heating cable of direct and alternating current is shown in FIG. 1 and FIG. 2, respectively. The cable contains conductive conductors 1, additional coating 2 for each core, polymer insulation 3, winding 4 for insulation, cushion 5, general armor 6, filler 7. The proposed cables are wider, provide less thermal resistance to heat transfer from the armor to the compressor pipe, which allows you to increase the temperature of the oil and reduce its viscosity. Controlled operation of wells with a heating system continues.

Literature:

1.Persiyantsev M.P. - Oil production in difficult conditions. Moscow, Nedra, 2000

2.Burenkov A.E. - The heating cable. Collection “Perm Region for the Oil and Gas Industry, Perm, 2001

3.Burenkov A.E., Makienko G.P., Merzlyakov B.L., Smilgevich V.V., Kholodny S.D. - Calculation of heating the oil flow in the well when using a heating cable. Collection “Perm Region for the Oil and Gas Industry, Perm, 2001

Claims (6)

1. A flat heating cable for an oil well heating system, comprising conductive conductors with single or double layer insulation made of a polymer material, arranged in parallel, a cushion or sheath overlaid on them, and general armor, characterized in that the width of the flat part is increased and the thermal resistance of heat transfer from the surface is reduced cable to the tubing of the installation for oil production. 2. A flat heating cable for an oil well heating system according to claim 1, characterized in that the width is increased due to the execution of each conductive core from two separately insulated conductors or the use of filler between the conductors and with a constant voltage heating of the wells, cable length, power consumption , the magnitude of the current and voltage are related by the relation

where I is the value of direct current, A;
U is the voltage, V;
P ₀ - power consumed by the cable per unit length, W / m 3. A flat heating cable for an oil well heating system according to claim 1, characterized in that in a three-core cable, an increase in width is achieved by performing at least one conductive core of two separately insulated conductors, or by using a filler between the isolated conductors and the cable length consumed them power, current and voltage in the heating system are related by the ratio

where I is the phase current, A;
U _l - the linear voltage of a three-phase system with a frequency of 50 Hz, V;
P ₀ - power consumed by the cable per unit length, W / m;
cosφ is the power factor.  4. Flat heating cable for the oil well heating system according to claim 1, characterized in that for the insulation of each core, a winding of tape material is carried out with the subsequent laying of a pillow.  5. Flat heating cable for the oil well heating system according to claim 1, characterized in that an additional coating of electrical insulating varnish or tin or its alloy is applied to the surface of each copper conductive core. 6. Flat heating cable for the oil well heating system according to claim 1, characterized in that the armor is made of steel tape with a relative elongation of at least 30%.