RU2249672C1 - Oil well heater - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: device has current source, output cable, and heating cable. Current-conductive filaments of heating cable on one end are connected to each other, and by other ends via output cable are connected to current source. Parameters of said current source, output cable and heating cable are linked by following relation:

where L_k - length of heating cable, L - total length of heating and output cables, U - current source voltage,

- power coefficient, R₀ - active resistance of one meter of phase (current-conductive line) of heating cable, R₁ - active resistance of one meter of phase (current-conductive line) of output cable, P₀ - active power, consumed by one meter of heating cable. Output cable passes through well mouth and downwards into well along hoisting pipe and is electrically connected to heating cable placed in the well. Brackets connect cables to hoisting pipe, placed inside casing pipe, with even spaces.

EFFECT: higher efficiency.

1 dwg

Description

FIELD OF THE INVENTION

The heater belongs to the equipment of oil wells and is designed for electric track heating of a highly viscous oil and gas mixture of wells equipped with sucker rod pumps or submersible electric pumps, in order to maintain optimal thermal conditions in the wells for the prevention and elimination of alumina-resin-paraffin deposits.

State of the art

A cable line is known, consisting of interconnected low-temperature and high-temperature taps with different resistivities, each of which consists of insulated conductive conductors in a common forming shell, on which a pillow is placed under armor and armor, the cores of each of the taps are connected in pairs, the junction made one-piece, on top of the joints of each pair of cores an insulating heat-resistant shell is laid, then a general forming insulating shell, a pillow and armor, and a heat-insulating sheathing is laid on each core, a general insulating formative sheath, a pillow and armor are laid on pairwise conductive wires of each of the branches and the junction of the wires is continuous along the entire length of the cable line (RF Patent for Utility Model No. 10000, published May 16, 1999. Bull. No. 5.).

Signs of a known cable line, coinciding with the features of the claimed invention, are the presence of a heating cable.

The reason that prevents obtaining a technical result in a known cable line, which is provided by the invention, is that the heating cable is made of two taps - a low-temperature and a high-temperature, as well as in the absence of an output cable.

A heater for an oil well is known, comprising a first heating element located in a tubing in the form of a cable connected to a power source, while at the end of the cable there is an uninsulated section with conductive weights that provide electrical connection to one or more parallel cable conductors through which a current is passed, with a tubing, which is the second heating element; while the cable is connected to the positive terminal of the power source, and the tubing to the negative. The cable, in addition, is equipped with temperature sensors and connecting wires embedded in it for connecting them to the measuring device (Patent RU No. 2171363 C1, Application No.2000131536 / 03, filing date 2000.12.18, publication of the formula 2001.07.18).

Signs of a known heater, coinciding with the features of the claimed invention, are the presence of a heating cable and a current source to which this cable is connected.

The reason that prevents obtaining a technical result in a known heater, which is provided by the invention, is the presence of conductive loads and the use of a tubing as a heating element.

The closest analogue (prototype) for the claimed heater is a heater for an oil well, including an adjustable current source, a regulator and a heating cable that contains a common armor with a cushion for this armor, thermally insulated conductive heating conductors parallel to the inside of the armor, connected at one end of the cable between themselves, and with other ends connected to an adjustable current source, as well as laid parallel to the heating cores in the spaces between them and the common armor filling cores, at least two of which are made in the form of insulated copper wires connected to each other at one end of the cable, and connected to the shoulder of the electrical measuring bridge with the other ends, the measurement diagonal of which is connected to the input of the regulator (RF Patent No. 32186 for utility model; published 10.09 .2003, Bull. No. 25).

Signs of a known heater that coincide with the features of the claimed invention are the presence of a current source and an electric heating cable, the conductive heating cores of which are connected at one (lower) end of the cable and connected to the current source with the other ends.

The reason that prevents obtaining a technical result in a known heater, which is provided by the invention, lies in the direct connection of the heating cable to the current source.

Disclosure of invention

The problem to which the invention is directed is to provide the possibility of preventing and eliminating asphalt-resin-paraffin deposits in oil wells while simplifying the design of the regulator (or eliminating it) and minimizing material and energy costs.

The technical result that mediates the solution of this problem is to minimize the length of the heating cable.

The technical result is achieved in that the heater for an oil well includes a current source made in the form of either a three-phase or two-phase alternating current source, or a single-phase alternating current source, or a direct current source, an output cable, as well as a heating cable, the conductive wires of which on one of its the end are interconnected, and the other ends are connected to the current source through the output cable, while the parameters of the above-mentioned current source, output and heating cable are firs linked by the following relation:

where L _k is the length of the heating cable,

L is the total length of the heating and output cables,

U is either the voltage between the phases of the source of a three-phase or two-phase alternating current, or the voltage between the phase and zero of the source of a single-phase alternating current, or the voltage of the DC source,

cos φ is the power factor (φ is the angle between the current flowing through the heating and output cables and the voltage U), while in the case of using a constant current source, cosφ = 1,

R ₀ - either the active resistance of one meter of the phase of the heating cable in the case of using a source of three-phase or two-phase alternating current, or the active resistance of one meter of the conductive line of the heating cable in the case of using a source of single-phase alternating current or a source of direct current,

R ₁ - either the active resistance of one meter of the phase of the output cable in the case of using a source of three-phase or two-phase alternating current, or the active resistance of one meter of the conductive line of the output cable in the case of using a source of single-phase alternating current or a direct current source,

P ₀ - active power consumed by one meter of heating cable.

New features of the claimed heater are the output cable, through which the heating cable is connected to the current source, as well as the length L _{k of the} heating cable, the total length L of the heating and output cables, voltage U of the current source, active resistance R _{0 of} one meter any conductor heating cable resistance R ₁ of one meter outputting any electrical conductor cable, and power P ₀ consumed one meter heating cable connected elations:

Brief Description of the Drawings

The drawing shows a functional diagram of a heater for an oil well.

The implementation of the invention

The drawing shows an oil well 1 having one or more casing 2 passing through the well. The riser 3 passes through the casing 2 to the surface. The wellhead 4 is located on the surface. The pressure pipe 5 extends from the wellhead 4 to transmit produced fluids.

The oil well heater comprises a heating cable 6, an output cable 7 and a current source 10. The conductive wires of the heating cable are made of steel, copper or aluminum, and the conductive wires of the output cable are made of copper or aluminum. In addition, the heating cable 6 in cross section has a flat, round or convex-concave shape and is designed to prevent the buildup of hydrates, ice, asphaltenes and paraffin wax (paraffins) or other heat-sensitive substances that can be deposited on the inner surface of the pipe 3. If the heating the cable is made flat and convex-concave, then it is placed outside along the lifting pipe 3 (as shown in the attached figure), and if round, then inside the lifting pipe 3 (not shown). Moreover, its lower point 8, in which there is an electrical connection between the lower ends of the conductive conductors of the cable, is located in the zone of the beginning of the proposed paraffin formation. The output cable 7 passes through the wellhead 4 and down into the well along the lifting pipe 3 and is directly electrically connected to the upper ends of the conductive wires of the heating cable 6 by the lower ends of its conductive cores and the current ends 10 by its upper ends. The brackets 9 attach cables 6 and 7 (if the cable 6 is made flat or convex-concave) to the lifting pipe 3 at regular intervals. In addition, the current source 10 can be made in the form of a three-phase, two-phase or single-phase AC source or in the form of a DC source. In the first case, cables 6 and 7 have at least three conductive cores according to the number of phases of the source 10 (cores may be larger). In the second, third and fourth cases, each cable has at least two conductive wires. When using a three-core cable in these cases, either only its two conductors are used, or two conductors are connected in parallel, so that they actually form one core. At the same time, it was experimentally established that the minimum energy consumption of the heating cable 6, which ensures the guaranteed effect of preventing paraffin formation in the well, is provided if the length L _{k of the} heating cable 6, the total length L of the heating 6 and the output cable 7, the voltage U between the phases of a three-phase or two-phase AC source current 10 (or voltage U between phase and zero of a single-phase alternating current source 10, or voltage U of direct current source 10), active resistance R _{0 of} one met phase of heating cable 6 (in case of using a source of three-phase or two-phase alternating current) or resistance R _{0 of} one meter of the conductive line of heating cable 6 (in case of using a source of direct current or single-phase source of alternating current), active resistance R _{1 of} one meter of phase of the output cable 7 (in the case of two-phase or three-phase source of alternating current) or the resistance R ₁ of one meter outputting a conductive line cable 7 (in the case of the source DC or single phase AC) power P ₀ consumed one meter heating cable 6 and power factor cosφ related by:

The operation of the heater for an oil well is as follows.

Preliminarily, based on the specified parameters of the depth of onset of paraffin formation, the electrical parameters of the available heating 6 and output cables 7 (R ₀ , R ₁ ), the minimum required power supplied by the heating cable 6 (and, accordingly, the power P ₀ consumed by one meter of this heating cable 6), preventing said wax formation, and predetermined power source voltage according to the above mathematical relationship determined by the needs length L _k of the heating cable 6. Further ka ate 6 and 7 are electrically interconnected and arranged on the riser 3 by means of brackets 9, so that the lower end of the heating cable 6 located at a depth intended start wax formation. In this case, the lower ends of the conductive cores of the heating cable 6 are pre-connected to each other. After the cables 6 and 7 are installed in the well, the cable 7 with its upper end is connected to a current source 10 at which the required voltage U is set. The current source 10 is turned on, as a result of which a three-phase or two-phase continuously or periodically flows through the conductive cores of the heating cable 6 alternating electric current (or single-phase alternating current, or direct current) from source 10. Current flows and heats these conductors, from which heat is transmitted through the heat-insulating dielectric sheath of the heating cable It goes to the heating surfaces of the cable, and from them to the pipe 3, preventing the formation of paraffin and other heat-sensitive substances in the well. At the same time, the length of the heating cable 6, calculated using the above ratio (which was determined experimentally), provides for other parameters of the heater that the oil is heated in the well in such a way that the formation of paraffins is avoided with the lowest possible consumption of electrical energy. It is also possible that in some cases, the length L _{k of the} heating cable will be a predetermined value determined by the operating conditions of the well. Then, using the above mathematical expression, either the voltage U of the current source 10 is determined, which is necessary to ensure the rated power P ₀ supplied to the heating cable 6, or the electrical parameters of the cables 6 and 7 (R ₀ -R ₁ ).

Claims (1)

A heater for an oil well, including a current source made in the form of either a three-phase or two-phase alternating current source, or a single-phase alternating current source, or a direct current source, an output cable, as well as a heating cable, the conductive wires of which are connected at one end, and the other ends are connected to the current source through the output cable, while the parameters of the above-mentioned current source, output and heating cables are interconnected by the following Ocean:

where L _k is the length of the heating cable, L is the total length of the heating and output cables, U is either the voltage between the phases of the source of a three-phase or two-phase alternating current, or the voltage between the phase and zero of the source of a single-phase alternating current, or the voltage of the DC source, cosφ - power factor, R ₀ - either the active resistance of one meter of the phase of the heating cable in the case of using a source of three-phase or two-phase alternating current, or the active resistance of one meter of the conductive line of the heating cable in the case of using a source of single-phase alternating current or a source of direct current, R ₁ - either the active resistance of one meter of the phase of the output cable in the case of using a source of three-phase or two-phase alternating current, or the active resistance of one meter of the conductive line of the output cable in the case of using a source of single-phase alternating current or a direct current source, P ₀ - active power consumed by one meter of heating cable.