RU2784121C1 - Downhole installation for the production of high-viscosity oil - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry and is intended to influence the bottomhole zone of a well in order to reduce the viscosity of the well fluid before receiving a submersible pump, to increase its performance and prevent the formation of asphaltene-paraffin-hydrate deposits. A downhole installation for the production of high-viscosity oil consists of a control station with a power regulator, which is connected to an industrial power supply network, a transformer, a submersible motor that drives the submersible pump, a telemetry unit, and an electromagnetic emitter unit. Wherein the control station with its output is connected to the input of a power transformer, the output of which is connected by a power cable to the input of the submersible electric motor. The downhole installation includes a radiator unit that provides thermal effect on the downhole fluid, a control unit and a connection unit. Moreover, the connection unit with its first input is connected to the output of the submersible electric motor, and the output is connected to the first input of the electromagnetic emitter unit, the first input of the radiator unit and the first input-output of the telemetry unit, in which the second input-output is connected to the first input-output of the control unit. The second output of the control unit is connected to the second input of the radiator unit. Its third output is connected to the second input of the electromagnetic emitter unit. The fourth output is connected to the second input of the connection block.

EFFECT: increasing the efficiency of the technological process of producing high-viscosity oil with electric submersible pumps by improving the reliability of submersible equipment, simplifying tripping operations.

4 cl, 5 dwg

Description

The invention relates to the oil and gas industry and is intended to influence the bottomhole zone of a well in order to reduce the viscosity of the well fluid, before receiving a submersible pump, to increase its performance and prevent the formation of asphaltene-paraffin-hydrate deposits.

The methods based on the impact on the well fluid by thermal and electromagnetic fields, chemical reagents have received the greatest practical distribution. To form a thermal field, direct-acting heaters are widely used (heating of elements with direct flow of electric current through them) and induction heating (with indirect heating of structural elements by eddy currents when exposed to a high-frequency magnetic field). The use of induction heating of structural elements located in the borehole space is inferior in terms of the efficiency of direct heating, however, interest in this method does not wane. The explanation lies in the following. When using direct-acting heaters, significant power is required to achieve the desired effect. For example, according to [Strunkin S. I. et al. “The use of installations for heating the bottomhole formation UPPZ-30 at the facilities of PJSC Orenburgneft”, Zh. "Engineering Practice", No. 12/2015] heater power was maintained at 25 kW. When using induction heaters, in some cases, there is a combined effect - thermal and electromagnetic fields. Thus, there are prerequisites for increasing the energy efficiency of the process by combining thermal and electromagnetic effects (a thermal field increases the mobility of complex hydrocarbon molecules, and an electromagnetic field contributes to breaking bonds in their structure).

Known downhole installation [RF Patent No. 2710057 C1, IPC E21B 43/24, 36/04, publ. December 24, 2019], consisting of a heater, a pump, a tubing pipe, valves, nozzles, a power cable and a geocable, wellhead fittings, a control station, a transformer. The control station maintains the predetermined temperature of the heater, the heater is installed under the pumping unit, while heating is performed continuously or short-term-cyclically, and the heating temperature is controlled using the control system, the heater is selected with an inductive and/or resistive principle of operation. The advantage of this solution is automation and the possibility of optimizing control actions based on information feedback. The disadvantages include the need to use two cables, which creates difficulties in the placement and installation of equipment in the well and in the process of starting and operating the process. In the case of using an induction heater, there is no possibility of independent control of the parameters of thermal and electromagnetic effects on the well fluid.

An induction downhole heater is known [RF Patent No. 2721549 C1, IPC E21V/36/04, H05V6/10, publ. The magnetic circuit is made in the form of toroidal magnetic circuits - elements made of transformer steel, placed continuously along the entire length of the core. The conductive wire is placed over the magnetic circuit by a continuous winding. One end of the housing is provided with a current lead. The lower end of the housing is articulated with the hydraulic compensation unit. The heater is made with the possibility of connection at the top and bottom with a telemetry system. The advantage of the device is its versatility of technological application. The disadvantage of the device is the need for an additional cable, in addition to the power cable, when using a submersible pump with an electric drive, as well as the limited upper frequency range of electromagnetic effects due to high-frequency shielding of the outer casing.

A known system for powering a submersible motor and heating the well fluid [RF Patent No. 2353753 C1, IPC E21V 36/04, H01V 7/18, publ.27.04.2009], which consists of a submersible motor (SEM), control station, matching power transformer and cable line connecting them. The cable line consists of at least two sections of the electric cable (EC), one of which is connected to the ground power units and control station, and the second to the SEM, between which there is a heating section of the cable (HUK), the current-carrying conductors of which are electrically in series connected by conductive conductors EK. An extension cable with a cable gland for connection to the SEM can be used as an EC. NUK conductive conductors are made of steel, and EC conductive conductors are made of copper. The resistance of each NUK conductive core and the phase supply voltage of the entire system as a whole are determined by the above mathematical expressions. At the same time, in the nominal mode, the active powers of the SEM and NUK are distributed equally, it is under this condition that the SEM has the maximum efficiency when powered from an alternating current source with a fixed voltage amplitude. The advantage of this system is the versatility of the use of the power cable. The disadvantage is the low efficiency of the heating process due to the limited temperature, surface area of the NUK (low specific energy) and the choice of position in the well.

Known installation [RF Patent No. 98042 U1, IPC E21V 36/04, publ. 27.09.2010], consisting of a submersible electric motor SEM, a control station, a matching power transformer, a heating control station containing a control unit, a generator with a frequency range of 5-200 kHz, a rectifier, power output switches connected in a bridge or half-bridge circuit; a ground-based matching device containing a set of capacitors of the required capacity, connected in parallel, and an inductor connected in series with the specified bank of capacitors; submersible matching device, also containing a set of capacitors of the required capacity, connected in parallel between the current-carrying conductors of the cable; and submersible cable line. The ground matching device and the submersible matching device are spatially separated from the surface to the SEM. The installation uses one cable to connect the SEM and the downhole heater, dividing the electricity between them by frequency. This technical solution is based on the position of classical electrical engineering, according to which, when connecting two series LC circuits tuned to resonance, their resistance will be minimal at the resonant frequency and maximum at other frequencies (the quality factor of the circuits is determined). Accordingly, high-frequency energy must be supplied to the heater, and low-frequency energy to the SEM. The advantage of the device is the versatility of using a power cable. The main drawback of the device is significant difficulties in practical implementation, which consists in the fact that it is very difficult to tune two circuits on the surface and in the well into resonance, because resonance, in addition to the parameters of the circuits, is affected by parasitic variable parameters - the capacitance and inductance of the cable, transformer and SEM. It is practically difficult to ensure sufficient quality factor of the circuits, ensuring their high overall power in conditions of limited dimensions of the well space,

The closest to the proposed invention is a multifunctional automatic complex station of an intelligent well [RF Patent No. 128894 U1, IPC E21 / B 47/00, publ. lines, electrical communication lines, and ground equipment, consisting of a control device connected through inputs and outputs to ground and submersible equipment, with the ability to control a submersible motor and cable heating. The station has a high-frequency generator with the ability to transfer energy to the inductor in the well through separate power circuits, a communication module with the ability to control, receive and transmit data via communication channels, a reagent storage tank, a dosing pump, a pressure gauge, a level gauge, pipeline fittings, an inductor, a submersible heating cable line, additionally equipped with a capillary pipeline. Submersible telemetry is connected to additional power circuits of the inductor. The advantage of this technical solution is the possibility of a sufficiently effective complex impact on the produced fluid. The disadvantages are as follows. This is, firstly, the presence of at least two power cables - for heating and connecting the pump drive, together with an inductor, a special cable containing separate cores for connecting a submersible motor and an inductor (the need for a special cable limits industrial use), which greatly complicates the process of tripping operations and creates difficulties in placing downhole equipment in a limited well space. Secondly, the use of an inductor for heating and electromagnetic action at the same time does not allow one to independently control the parameters of this effect. Thirdly, the placement of a high-frequency generator on the surface with an inductor connected via a sufficiently long line is accompanied by significant attenuation and losses of the input energy due to the distributed parameters of the long line.

The technical result of the invention is to increase the efficiency of the technological process of production of high-viscosity oil by electric submersible pumps by reducing the cost of submersible equipment, increasing its reliability, simplifying tripping operations.

The specified technical result is achieved by a downhole installation for the production of high-viscosity oil, consisting of a control station with a power regulator, which is connected to an industrial power supply network, a transformer, a submersible motor that drives a submersible pump, a telemetry unit, an electromagnetic emitter (inductor) unit. its output is connected to the input of a power transformer, the output of which is connected by a power cable to the input of the submersible motor. The downhole installation includes a thermal radiator that provides a thermal effect on the downhole fluid, a control unit and a connection unit. The connection unit is connected with its first input to the output of the submersible electric motor, and its output is connected to the first input of the electromagnetic emitter unit, the first input of the radiator unit and the first input-output of the telemetry unit. The second input-output of the telemetry unit is connected to the first input-output of the control unit, and the second output of the control unit is connected to the second input of the radiator unit, and its third output is connected to the second input of the electromagnetic emitter unit, and the fourth output is connected to the second input of the connection unit.

According to the invention, the connection unit, the input of which is connected to the output of the submersible motor, and the output of which is connected to the radiator unit and the electromagnetic emitter unit, makes it possible to control the operating mode of the downhole installation.

According to the invention, the telemetry unit, connected through the connection unit to the output of the submersible motor, provides half-duplex communication over a communication channel combined with the power cable circuits.

According to the invention, the submersible motor together with the power cable form an additional heating element for the downhole fluid.

The essence of the invention is illustrated by drawings, where figure 1 shows a block diagram of the installation, figure 2 is a layout diagram, figure 3 is a simplified block diagram of the installation operation algorithm, figure 4 and figure 5 are functional diagrams of implementation options connection block.

The installation (Fig.1,2) contains: 1 - control station with a power regulator (CS), 2 - power transformer (T), 3 - submersible motor with a submersible pump (SEM), 4 - connection unit (BP), 5- telemetry unit (BT), 6 – radiator unit (BR), 7 – electromagnetic emitter unit (inductor), hereinafter referred to as BEM; 8 - control unit (CU), 9 - thermal insulator, 10 - centralizer, 11 - casing, 12 - submersible pump receiving module.

Consider the operation of the installation, based on a simplified block diagram of the algorithm (figure 3). We believe that the installation should operate in a complex mode - thermal and electromagnetic effects on the well fluid, along with its pumping, at steady-state parameters. At the same time, unit 5 monitors fluid parameters, parameters of SEM 3, BR 6, BEM 7 and transmits measurement information via a communication channel combined with power cable circuits to CS1 and via a local network to BU 8, and also broadcasts commands and settings to BU 8 BP 4 distributes the input electric power and regulates the parameters of the impacts, based on the commands and settings of the CS 1, broadcast by BT 5, between the BR 6 and BEM 7, while the CS 1 regulates the parameters of the input power, taking into account the mode of operation of all devices. BU 8 can also operate in automatic mode, in accordance with a given algorithm, using information feedback from BT 5.

The operation of the installation in the so-called unitary mode has two options. The first option is the impact of a thermal and electromagnetic field on the well fluid without pumping it to the surface, which, for example, is possible with a repeated-short-term process of fluid lifting, when the rate of its inflow from the formation into the well does not match the pump performance. In this embodiment, the control station 1 switches, by means of a voltage regulator, to a reduced voltage mode while maintaining the current in the power circuit close, for example, to the nominal value. For SEM 3, this mode is known as the experimental short circuit mode [Kopylov I.P. Electrical Machines: Textbook for High Schools - M.: Energoatomizdat, 1986.-360s]. In this variant, the exposure process is accompanied by control of the state of the fluid in the well space. When the set values are reached, a return to the very beginning of the cycle occurs, i.e. deciding on the nature of the continuation of the process.

The second option is only the rise of the well fluid. Here, BP 4 minimizes the power supplied to BR 6 and BEM 7. Almost all of the input power is applied to the SEM. This option is well known and widely used in the production of hydrocarbons with acceptable viscosity.

For further explanation of the operation of the installation, see Fig. 2 and 4, 5.

According to the above version of the schematic layout diagram of the equipment location in the well part (Fig.2), at the base of the SEM 3, BP 4, BT 5, BU 8, BEM 7 are sequentially located and further through the thermal insulator 9–BR 6. Through the thermal insulator 9 in the composition of the assembly includes a centralizer 10 for positioning in the casing string 11.

In accordance with the implementation option of BP 4 (Fig. 4), the input circuits of the stator windings of the SEM 3 - WD-A, WD-B, WD are connected to the secondary windings of the transformer - WT-A, WT-B, WT-C -C. To the output circuits of these windings, elements BR 6 - R1, R2, R3 are connected, connected in a three-phase star. In parallel to the output circuits of the windings of the SEM 3, an electronic switch (EC), which is part of the PSU 4, is included, consisting of a three-phase bridge rectifier on diodes VD1 ... VD6 and a switching transistor VT, controlled by the BU 8. The power supply circuits of the BEM 7 are schematically shown as Rn. When VT is closed, the stator windings of the SEM 3 are connected into a three-phase star through Rn, and the elements R1, R2, R3 are shunted. When VT is opened, the stator windings of the SEM 3 are closed into a three-phase star through the BR6 elements. In this case, the distribution of power supplied to the BR 6 is carried out in accordance with the ratio of the closed and open state of the EC. In the closed state, all power is applied to the windings of the SEM 3 and Rn, in the open state it is distributed between the SEM 3 and BR 6. An EC operating mode with a relatively high clock frequency, of the order of several kilohertz, is advisable. This is quite possible, taking into account the inertia of thermal processes in BR 6 and the sufficiently high inductance (L) of the stator winding of SEM 3 (according to the well-known switching law, the current in the inductive circuit changes according to the time constant τ = L/R). The power adjustment of the BR 7 in this circuit is carried out by varying the value of the resistance Rn.

The diagram of Fig.5 shows another example of the functional diagram of the PSU 4. The designations and purpose of the elements in the diagram are similar to Fig.4. Here, with the key VT closed, the outputs of the stator windings WD-A, WD-B, WD-C are closed into a three-phase star through diodes VD1 ... VD6, transistor VT (with a negligible resistance of the closing loop), and all the instantaneous power is applied to SEM 3. When VT is opened in series with these windings, the power supply circuits Rn1 - block BR 6, Rn2 - block BEM 7 are switched on in series, and the instantaneous power is redistributed in accordance with the ratio of the time of the open and closed state of VT, the parameters of the SEM 3, Rn1, Rn2.

The practical implementation of the installation components is known. CS 1, BT 5, PED 3 in two-section design with transit of the output circuits of the stator winding of the first section are serial industrial products. There are various designs of radiators, for example, [RF Patent No. 2559975 C1, IPC E21B 47/07, publ. 20.08.2015]. BU 8 is implemented on the basis of programmable logic using microcontrollers of various types. It should be emphasized that the control unit for synchronous information interaction with the control station may have its own communication channel - wired, combined or wireless.

An important component of the installation is an electromagnetic emitter block that performs an electromagnetic effect on the well fluid. The implementation of such a device is known, for example, [RF Patent No. 2529689, IPC E21B 43/25, 28/00, publ. 27.09.2014 Bull. No. 27]. In this case, there is a combined effect - thermal and electromagnetic fields. This increases the energy efficiency of the process (the thermal field increases the mobility of complex hydrocarbon molecules, and the electromagnetic field contributes to the breaking of bonds in their structure, thereby reducing the viscosity due to the formation of lighter fractions of hydrocarbons).

It should also be noted that the submersible motor together with the power cable is used as an additional heating element for the downhole fluid.

Thus, the proposed invention makes it possible to increase the efficiency of the technological process for the production of high-viscosity oil by electric submersible pumps due to:

- reducing installation costs while maintaining functional versatility;

- significant simplification of tripping operations;

- increasing the reliability of the installation.

Claims (4)

1. A downhole installation for the production of high-viscosity oil, consisting of a control station with a power regulator, which is connected to an industrial power supply network, a transformer, a submersible motor that drives a submersible pump, a telemetry unit, an electromagnetic emitter unit, and the control station is connected to the input with its output a power transformer, the output of which is connected by a power cable to the input of the submersible electric motor, characterized in that the downhole installation includes a radiator unit that performs a thermal effect on the well fluid, a control unit and a connection unit, the connection unit being connected by its first input to the submersible electric motor output, and the output is connected to the first input of the electromagnetic emitter unit, the first input of the radiator unit and the first input-output of the telemetry unit, in which the second input-output is connected to the first input-output of the control unit, and the second output of the control unit connected to the second input of the radiator unit, and its third output is connected to the second input of the electromagnetic emitter unit and the fourth output is connected to the second input of the connection unit. 2. The installation according to claim 1, characterized in that the connection unit, the input of which is connected to the output of the submersible motor, and the output of which is connected to the radiator unit and the electromagnetic emitter unit, allows you to control the operating mode of the downhole installation. 3. Installation according to claim 1, characterized in that the telemetry unit, connected through the connection unit to the output of the submersible motor, provides half-duplex communication over a communication channel combined with the power cable circuits. 4. Installation according to claim 1, characterized in that the submersible motor together with the power cable form an additional heating element for the downhole fluid.

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