RU2256065C1 - Device for operation of electric down-pump in oil-gas well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: device has electric down-pump mounted in a well with power cable from electric engine. Device also has operation mode set-point device, deep telemetry block with sensors of parameters of well condition and electric pump, debit measuring means, mounted on outlet line, voltage of converter, connected to control station. The latter is connected to electric engine feeding cable. According to invention into device additionally inserted are adaptive adjuster, block of dynamic model of schematic bed-well-down-pump, block for identification of dynamic model, block for identification of parameters of face-adjacent bed zone.

EFFECT: higher quality.

5 dwg

Description

A device for operating a submersible electric pump unit in an oil and gas well relates to the field of oil production and can be used to increase the efficiency of the well.

A device is known that implements a method for automatically controlling the operating mode of a well equipped with a submersible centrifugal electric pump [1]. The device comprises a submersible centrifugal electric pump installed in the well, including the pump itself and the submersible drive motor with an in-depth manometer-thermometer and tread, tubing, a control station with a power transformer and a power supply cable, a deep communication channel, a frequency converter, an adjustable fitting, a return valve and pressure gauges mounted on the flow line.

The reasons that impede the achievement of the technical result indicated below when using a known device include the fact that this device in real time cannot determine the optimal operating mode of the “reservoir - well - submersible pump” system and maintain it, since the device does not have identification blocks and adaptive regulator. In addition, throttling at the wellhead does not provide energy-saving modes of operation of the electric pump and the potential flow rate of the well.

The closest set of features to the claimed device is a device for implementing a method of operating submersible centrifugal pumping units in a group of wells [2]. The device comprises submersible centrifugal pumping units installed in the wells with power cables for their electric motors, a voltage frequency converter, state parameters sensors for each well and its pump unit, connected to a system for measuring and generating electric motor control signals, switching devices for connecting electric motor power cables to the field network and voltage frequency converter, unit for determining the optimal sequence of actions by control signals avleniya. This device is taken as a prototype.

The reasons that impede the achievement of the technical result indicated below include the fact that the system for measuring and generating electric motor control signals used in this device provides control of electric pump units only according to a predetermined task without reference to real-time parameters of the “reservoir - well - submersible pump” system ”And bottomhole formation zone. This device does not provide the optimal mode of operation of the wells and the quality of transients when switching the power of electric pump units.

The essence of the invention lies in the fact that in a device for operating a submersible electric pump unit in an oil and gas well, comprising a submersible electric pump unit installed in the well with a power cable for its electric motor, a submersible telemetry unit with sensors for well condition parameters and an electric pump unit, a flow meter installed on the flow line A voltage frequency converter equipped with a controller and connected to a control station equipped with a controller and connected to an electric motor power cable, an operating mode adjuster, an adaptive regulator, a dynamic model block of the reservoir – well – submersible pump system, a dynamic model identification block, and a formation bottom parameter identification block have been additionally introduced. In this case, the outputs of the operating mode setter are connected to the inputs of the adaptive controller, the unit of the dynamic model of the “reservoir - well - submersible pump” system and the unit for identifying parameters of the bottomhole formation zone, the output of which is connected to the input of the setter of the operating mode, the output of the flow meter is connected to the inputs of the dynamic identification unit model and unit for identifying parameters of the bottomhole formation zone, the second inputs of which are connected to the output of the control station, the second output of which is connected to the second input of the adaptive control a generator, the output of which is connected to the input of the voltage frequency converter, the outputs of the block of the dynamic model of the “reservoir - well - submersible pump” system and the identification block of the dynamic model are connected to the third and fourth inputs of the adaptive controller.

Achievable technical result - improving the quality of regulation of a submersible electric pump unit for specified performance indicators, reducing the time of transient processes, reducing the load on the electric pump unit and energy costs by taking into account the real dynamic characteristics of the “reservoir - well - submersible pump” system.

Figure 1 presents a structural diagram of a well equipped with a submersible pump; figure 2 is a graph of the pressure recovery curve; figure 3 is a graph of the indicator chart; figure 4 is a graph of the calculated characteristics of the skin factor; figure 5 - graphs of changes in bottomhole pressure during the conclusion of the well to the mode and its maintenance.

A well equipped with a submersible electric pump unit (Fig. 1) contains a reservoir 1, production casing 2, a submersible drive motor 3 with a temperature sensor 4 inside its body, pump 5, tubing string 6, power supply cable 7, block 8 immersion telemetry with sensors 9 for pressure and 10 temperature of the borehole fluid at the intake of pump 5, sensors 11 and 12 for vibration acceleration in two planes of the motor body 3, flow meter 13, for example, an automatic group metering unit, about load or weight, in the flow line 14 of the well, a control station 15 with an integrated controller and a power transformer (not shown conventionally in FIG. 1), a voltage frequency converter 16 with an integrated controller (not conventionally shown in FIG. 1), an operating mode adjuster 17 , adaptive controller 18, block 19 of the dynamic model of the reservoir-well-submersible pump system, block 20 of identifying the dynamic model, block 21 of identifying parameters of the bottomhole formation zone.

The source of the borehole fluid is the reservoir 1, the communication with which is through the perforations in the casing 2 of the well. The main parameters of a submersible electric pump unit consisting of a pump 5, for example a centrifugal pump, and a submersible drive electric motor 3, are the capacity Q _Ж (m ³ / day), the developed head N (m water), and also the presence of pressure at the pump 5 intake not lower than a predetermined value at various frequencies f _I at the output of the voltage frequency converter 16. The submersible drive motor 3 forms, together with the voltage frequency converter 16 and the control station 15, a variable frequency drive with which the rotational speed n of the rotor of the electric motor 3 and, accordingly, the pump 5 are controlled.

The power conductive cable 7 serves to supply electricity to the submersible drive motor 3 and transmit signals from the immersion telemetry unit 8, including sensors 9 to 12, to the surface.

The meter 13 flow rate of the borehole fluid measures the current flow rate of the well, including with separation by product and water.

The control station 15 with an integrated controller and power transformer is designed to control, power and protect the submersible drive electric motor 3, process the signals of the submersible telemetry unit 8 and, together with the voltage frequency converter 16, to control the rotational speed of the rotors of the submersible drive electric motor 3 and pump 5.

The master 17 operating mode of the well, usually made in the form of an automated workplace of the operator (technologist) based on a personal computer installed in the control room of the oil production department, is used to calculate the potential flow rate of the well in accordance with its hydrodynamic parameters, setting the system operating mode selected by the operator “ reservoir - well - submersible pump ”and input control signal into adaptive controller 18.

Block 19 of the dynamic model in accordance with the operating mode of the system “reservoir - well - submersible pump" determines its design parameters and together with adaptive regulator 18 serves to ensure the potential flow rate of the well.

The dynamic model identification unit 20 determines the actual parameters of the “reservoir - well - submersible pump” system in accordance with its selected calculation model.

Unit 21 for identifying parameters of the bottom-hole zone of the formation determines the hydrodynamic parameters of the well to select, using the adjuster 17, the mode of the desired value of the potential flow rate.

Adaptive controller 18 and blocks 19, 20 and 21 as functional links of the proposed device can be implemented programmatically (digitally) using programmable controllers, including controllers of the control station 15 and voltage converter 16.

The device operates as follows.

The fluid from the reservoir 1 flows through the perforations into the production casing 2 of the well. The submersible drive motor 3, equipped with a temperature sensor 4 inside its housing, rotates the rotor of the pump 5. Next, the liquid is supplied to the surface through the column 6 of tubing. The submersible drive electric motor is powered by the power supply cable 7. Sensors 9 and 10 of the immersion telemetry unit 8 measure the pressure P _PR and temperature T _PR at the pump intake, sensors 11 and 12 - vibration acceleration α _x and α _Y in two planes of the motor casing 3, and also pump 5, taking into account their rigid connection and the presence of a common rotor (shaft). Information signals from the immersion telemetry unit 8, including sensors 9-12, are supplied in modulated form via a power current-supply cable 7 to the surface of the control station 15. The meter 13 flow rate of the well fluid installed in the flow line 14, measures the current flow rate of the well. Power management with the necessary protection against abnormal conditions in current, voltage, temperature T _D inside the housing and vibration accelerations α _X and α _{Y of the} submersible drive motor 3 is carried out by the control station 15.

The voltage frequency converter 16 sets and regulates (maintains) the operating mode of the dynamic system “reservoir - well - submersible pump” by changing the productivity of the pumping unit as a function of the bottomhole pressure of the well corresponding to the condition for matching the characteristics of the flow of the well, determined by the productivity of pump 3, and the characteristics of the well inflow ( real indicator diagram of the well).

Conducting hydrodynamic studies (GDI) of the well, in particular the removal of the HPC and the indicator diagram (ID), in the general case, is associated with laborious work associated with the need to measure pressure at the bottom with depth gauges, or “beating” the dynamic level. The proposed device greatly facilitates these procedures, allowing you to build the KVD and ID in automatic mode without additional tripping operations.

From the output of the flow meter 13, the signal of the current flow rate Q _Ж is supplied to the first input of the unit for identifying parameters of the bottom-hole zone of the formation; from the output of the control station 15, it processes the signal from block 8 of the submersible telemetry, the pressure signal P _PR is received at the reception of the pump 5.

When a well stop signal is supplied from the output of the setter 17 in the identification unit 21, the IDC is determined. Moreover, according to the testimony of the sensor 9, at certain intervals, the values of the pressure P _{PR of the} borehole fluid at the intake of the pump 5 are also recorded there, converted into the values of the bottomhole pressure P _Z , the pressure-measuring device is built (figure 2).

The reservoir pressure P _PL is defined as the value of P _Z at which the pressure drop assumes a position close to horizontal. Depression ΔP _D for each of the modes is calculated from the value of reservoir pressure:

ΔP _D = P _PL -P _Z.

ID is determined by the steady state method. To this end, from the output of the mode master 17, a control signal is supplied to the voltage frequency converter 16. Adaptive controller 18 processes a given signal, bringing the “reservoir - well - submersible pump" system to steady state. Data on the pressure of the borehole fluid at the pump intake (P _PR ) from the output of the pressure sensor 9 and the flow rate of the borehole fluid from the output of the flow meter 13 are supplied to the block 21 for identifying parameters of the bottomhole formation zone to construct an ID in the form P _З = Р _З (Q _Ж ) and its further interpretation into the classical form Q _Ж = Q _Ж (ΔР _Д ) (Fig. 3).

The productivity coefficient K of the well is also determined in steady-state conditions when the inflow from the well (Q _C ) is equal to the specified fluid withdrawal (Q _W ). For this, the dependence of Q _Ж = Q _Ж (ΔР _Д ) determines the angular coefficient of the rectilinear portion of the curve, which is the value of the productivity coefficient:

The skin factor is also calculated by the HPC, for example, by the method according to which the dependence curve ΔP = ΔP (lnt) is built and the value of the angular coefficient i is found.

The expression for determining ΔР = ΔP (lnt) has the form [3]:

или ΔР=ilnt-A,

or ΔP = ilnt-A,

Where

k is the permeability of the reservoir;

μ is the dynamic viscosity of oil in reservoir conditions;

h is the effective thickness of the reservoir;

χ - piezoconductivity;

r _with - well radius;

S is the skin factor.

From here the parameters are found:

where ε is the hydraulic conductivity of the reservoir.

Then the permeability of the reservoir:

The piezoconductivity and reduced piezoconductivity are calculated respectively as:

where m is the open porosity;

β _W - compressibility of the liquid;

β _P - compressibility of pore channels;

r _pp is the reduced radius.

Reduced well radius:

Skin factor:

Another common method for calculating the skin factor is to determine the pressure value in the well P _C , which is the intersection point of the continuation of the rectilinear section of the graph with the ordinate axis (Fig. 4).

Next, the skin factor is calculated by the formula [4]:

where b is the volumetric coefficient of oil.

Such parameters as effective formation thickness h, fluid viscosity μ, open porosity m, fluid compressibility β _Ж and compressibility of pore channels β _{П are} considered known.

Hydraulic conductivity can also be calculated using the coefficient of productivity from the formula [5]:

where R _k is the radius of the power circuit.

Thus, in block 21 of the identification of the parameters of the bottom-hole formation zone, the potential well production rate and the hydrodynamic parameters of the bottom-hole formation zone are determined in real time.

Depending on the mode command signal generated by the voltage frequency converter 16 according to the signal of the mode setter 17, the submersible drive motor 3 rotates with a certain frequency the rotor of the pump 5 pumping the well fluid Q _Ж.

To build an optimal control algorithm for the selected mode, the “reservoir - well - submersible pump" system is described by linearized equations in the form of sequential aperiodic links with transfer functions:

where k _ESP , T _ESP - transmission coefficient and time constant, respectively, of the electric pump unit;

k _SLE , T _SLE - transmission coefficient and time constant, respectively, of the well;

p is the Laplace operator.

Block 19 of the dynamic model of the system “reservoir - well - submersible pump" reproduces it in the form of two series-connected aperiodic links:

- расчетные коэффициент передачи и постоянная времени соответственно электронасосного агрегата;Where

- the estimated transmission coefficient and time constant, respectively, of the electric pump unit;

- расчетные коэффициент передачи и постоянная времени соответственно скважины.

- estimated transmission coefficient and time constant, respectively, of the well.

можно определить по данным испытаний электронасосного агрегата. Постоянную времени

системы “пласт - скважина” (второго звена) можно определить из предварительно снятой КВД. При этом

In the first link - the calculation model of the electric pump unit, the voltage signal of a certain frequency and amplitude U _{f is} converted into the flow rate of the well fluid Q _Ж. In the second link - the calculation model “reservoir - well” pumping out of the well fluid Q _Ж leads to a change in the bottomhole pressure R _З. First link time constant

can be determined by test data of the electric pump unit. Time constant

“reservoir - well” systems (second link) can be determined from previously removed HPC. Wherein

The calculation model of the system “reservoir - well - submersible pump" in the entire range of operating modes can also be represented in the form of a system of differential equations:

where A ^P , B ^P , C ^P , D ^P - given matrix of calculated coefficients;

The real system “reservoir - well - submersible pump" is a nonlinear continuous object described by the equations:

where A, B, C, D - matrix of coefficients;

H (Q _W ); G (U _f ); U (P _s ); R (Q _W ) - nonlinear functions.

Block 20 identification of the dynamic model contains a model of identifiable parameters [6] of the system “reservoir - well - submersible pump":

where the matrices A ^M , B ^M , C ^M , D ^M include tunable coefficients a ^M , b ^M , c ^M , d ^M , equal at the end of the identification process to the coefficients a, b, c, d of equations describing the “reservoir - well - submersible pump".

To minimize the difference in coefficients ΔA = AA ^M ; ΔB = B-B ^M ; ΔC = C-C ^M ; ΔD = DD ^M , the Lyapunov functions are chosen in the form of positive definite quadratic forms:

where K, L, M, N are positive definite diagonal matrices of given constant coefficients;

ΔА ^T , ΔВ ^T , ΔС ^T , ΔD ^T are transposed matrices of coefficient differences.

In real time, the dynamic model identification unit 20 determines the coefficients of the matrices A ^M , B ^M , C ^M , D ^M and provides control signals to the adaptive controller 18. The identification process is stably converging.

Comparison of the calculated coefficients of the matrices А ^P , В ^P , С ^P , D ^P and identifiable coefficients of the matrices А ^M , В ^M , C ^M , D ^М occurs in adaptive controller 18. Signals of the differences of the coefficients of equations describing the real system “reservoir - well - submersible pump ”, and reference coefficients δA = A ^M -A ^P ; δB = b ^M -b ^P ; δC = C ^M -C ^P ; δD = D ^M -D ^P are used to adjust the adaptive controller 18.

The control signal of the submersible pump at the output of the adaptive controller 18 has the form:

In order to ensure the stability of the dynamic system “reservoir - well - submersible pump" the Lyapunov function is set in the form of a positive definite quadratic form

where P is a positive definite matrix of coefficients.

The control w is sought in the form:

Where

Hyperplane σ switching control in a sliding mode:

Adaptive controller 18, block 19 of the dynamic model of the reservoir-well-submersible pump system, block 20 of identification of the dynamic model, block 21 of identification of parameters of the bottom-hole zone of the formation can be implemented in the form of program blocks using a cluster controller or a computer of the operator’s workstation, on the basis of which the mode switch 17 is implemented.

Literature

1. Pat. 2140523 RU, IPC E 21 V 43/00. A method for automatically controlling the operating mode of a well equipped with a submersible centrifugal pump / V.O. Krichke (RU). - 97110564/03; Claim 06/24/99; Publ. 04/10/01.

2. Pat. 2050472 RU, IPC F 04 D 15/00, F 04 D 13/10, E 21 V 43/12. A method of operating submersible centrifugal pumping units in a group of wells and a device for its implementation / P.T.Shemchenko, I.A. Gordon (RU). - 5023311/06; Claim 12/23/91; Publ. 12/20/95.

3. The regulation of hydrodynamic studies of oil producing and water injection wells in oil and gas fields No. 13-C01-01. M .: - NK "YUKOS EP", 2002. - P.42.

4. Persiyantsev M.N. Oil production in difficult conditions. - M .: Nedra, 2000. - P.307.

5. Methodology for calculating bottom-hole pressure and potential well production. - Ufa: 000 “YuganskNIPIneft”, 2001. - P.31.

6. Reference on the theory of automatic control / Ed. A.A. Krasovsky. - M .: Science. Ch. ed. physical - mat. lit., 1987. - p. 254.

Claims (1)

A device for operating a submersible electric pump unit in an oil and gas well, comprising a submersible electric pump unit installed in the well with a power cable for its electric motor, a submersible telemetry unit with sensors for the state parameters of the well and the electric pump unit, a flow meter installed on the flow line, a voltage frequency converter connected to the station control connected to the power cable of the motor, the mode dial, characterized in that the device is additional The adaptive controller, the dynamic model block of the “reservoir - well - submersible pump” system, the dynamic model identification block, the identification module of the bottomhole formation zone parameters were introduced; the outputs of the operating mode adjuster are connected to the inputs of the adaptive controller, the dynamic model of the “reservoir - well” system - submersible pump ”and the unit for identifying parameters of the bottomhole formation zone, the output of which is connected to the input of the master mode of operation, the output of the flow meter is connected to the inputs of the identification unit a dynamic model and a unit for identifying parameters of the bottom-hole zone of the formation, the second inputs of which are connected to the output of the control station, the second output of which is connected to the second input of the adaptive controller, the output of which is connected to the input of the voltage frequency converter, the outputs of the block of the dynamic model of the formation-well-submersible pump system ”And the identification block of the dynamic model are connected to the third and fourth inputs of the adaptive controller.

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