RU2677313C1 - Oil well operation method by the electric centrifugal pump unit - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to the field of the mining industry, namely, to the oil production by electric centrifugal pumps (ESP) units. After the ESP operation parameters entry into the control station, checking the installation tightness, setting the initial frequency of 50 Hz AC, setting the restriction on the pump temperature, recording the amperage and starting the ESP. At the same time recording the pressure at the pump inlet, the temperature at the pump and at the pump input. Pump is operation is performed up to the pressure value at the ESP inlet, greater than or equal to the oil with gas saturation pressure. When pressures equality is achieved, recorded the temperatures at the inlet and at the pump itself, and determining the well flow rate. At a constant or increasing for not more than 10 % pressure at the pump inlet for one or more hours, the ESP station is brought to the continuous operation mode. Fixing the well flow rate, pressure at the pump inlet, the temperature at the pump and at the pump inlet and the amperage, at that, the temperature difference on the pump surface with the temperature at the pump inlet remains constant or decreases by not more than 10% and stabilizes. With the pressure at the pump inlet is less than the saturation pressure and the said temperatures increasing difference, determining an increase in the well flow rate and, depending on its value, reducing the pump speed and bringing the installation to the continuous operation mode. With the pressure at the pump inlet above the saturation pressure, increasing the pump shaft rotation frequency, determining the current frequency and amperage, determining the pump temperature and continue the ESP operation with the most optimal flow rate, dynamic level, current and temperature on the pump surface values.

EFFECT: use of the invention allows to fully automate the launching process, bringing to the technological mode and monitoring the oil well ESP operation, which in turn will increase the ESP equipment overall reliability.

5 cl, 7 dwg

Description

FIELD OF THE INVENTION

The invention relates to the field of mining, namely, oil production by electric centrifugal pump (ESP) installations with a frequency-controlled electric motor and serves as a complete automation of the operation of a oil well by an electric centrifugal pump.

State of the art

There are patents for the partial automation of the process of bringing the ESP to the technological mode using a control station (SU) with a frequency-controlled electric current of a submersible electric motor.

The prior art known "Method of operating a low-flow well electric pump with variable frequency drive" (application No. 97110817/03, 06/19/1997). The known method includes the periodic repetition of cycles, including starting the pump with an increasing frequency of the supply voltage and pumping the liquid at a given frequency, and after reaching a predetermined pressure in the pipe string in the current cycle, reduce the frequency of the supply voltage until the pump is stopped and then maintained to ensure fluid flow from the reservoir the maximum frequency at which the pump does not resume the flow, and after reaching the specified pressure during the inflow at the pump intake, the cycle is repeated, restoring the pump supply by transferring it to an increased frequency, in the phase of the current cycle inflow, the frequency of the electric pump supply voltage is modulated in the frequency range corresponding to the pump parameters changing during the inflow process when the supply is stopped and resumed.

The prior art method is also known - the author N.P. Kuzmichev "The method of short-term operation of wells submersible pumping unit with electric drive (method Kuzmichev), (application number 2005128382/03 from 04.02.2011)

The prior art method is also known - the authors A.A. Chudnovsky, S.I. Zaitseva, A.V. Davydova and Gozzi Istvan “Method for producing well fluid”, (RF patent No. 2190087)

In well-known analogues, periodic pumping of well fluid and the expectation of accumulation of well fluid to a certain level are considered.

The control stations IRZ-512I-400, ELECTON-05F-400, ETALON-CR-400, ORION-03-400, etc., are also known in the prior art. where the automation of the start-up and operation process is carried out using the data of the pressure and temperature sensor (TMS) at the reception of the ESP installation. At the same time, data (pressure) from the telemetry system (TMS) is supplied to the control station (SU) as a “feedback” to control the pump speed so as to bring the “submersible pump - reservoir formation” system into coordinated operation. For example, when supplying a reservoir of 20 cubic meters. liquid per day, ESP installation with a capacity of 35 cubic meters per day at an AC frequency of 50 Hz, it is necessary to operate at a lower frequency, etc.

In all of the above analogues, the main technical drawback is the neglect of the temperature state of the centrifugal pump - namely, the rate of change of the temperature of the ESP pump. In all of the above analogues, the current strength on the submersible motor is taken as the basis - however, the same current strength can correspond to different values of the receiving pressure, gas content, water cut, gas factor, and saturation pressure. Such uncertainty in the dependence does not allow to respond unambiguously to a change in current strength. The strength of the electric current does not characterize the state of the electric centrifugal pump.

The prior art known "Method of automatic control of ESP with a valve motor." A known method in which the operation of the centrifugal pump is carried out with such a speed of the pump shaft that the temperature in the first section of the pump remains constant. Automatic control of the ESP with a valve actuator, and, for the "feedback" it is proposed to apply the temperature on the first section of the pump (2012111621/06, 03/26/2012.). However, the temperature of the liquid entering the pump is not taken into account, which does not allow to determine the temperature increase in the pump due to the heat generated in it.

Therefore, all these control stations are semi-automatic in terms of starting, putting into operation and monitoring the operation of the ESP unit due to the fact that:

a) the pressure at the pump intake cannot be used as the “feedback” parameter in that form;

b) the optimal pressure at the pump intake cannot be determined by specialists serving the control station;

c) the state of the electric centrifugal pump is not taken into account, since the temperature of the ESP, depending on the presence of gas in the pumped liquid at the intake, can vary from 10 to 100 degrees. The high temperature of the pump can lead to failure of the ESP due to a decrease in the electrical resistance of the cable-motor system or to the deposition of salts inside the pump;

d) the temperature of the pump as a feedback is not enough, since it does not take into account the temperature of the incoming liquid at the inlet to the pump, the condition of the submersible motor. For example, with an increase in the descent depth of the ESP installation, the temperature at the pump intake will be higher. Then, at the same temperature of the pumps at the same settings, the temperature increase in the pump, with a lower inlet temperature, will be greater than that of a pump with a high inlet temperature. This can lead to a false conclusion about the identity of the state of the plants and the same steps to regulate the temperature of the pumps, for example, by changing the speed of the pump shaft the same way. In fact, where the temperature increase is greater there, it is necessary to reduce the frequency of the alternating current by a large amount according to. We call the temperature difference at the pump and at the pump inlet the relative temperature.

As the closest analogue, the applicant proposes the above “Method of automatic control of a ESP with a valve electric motor”. This application (2012111621/06, 03/26/2012.) Takes into account the temperature of the ESP without taking into account the temperature of the gas-liquid mixture at the pump inlet. For the first time, “a change in the relative temperature of the pump” is taken into account, which eliminates the disadvantages of items a) - d). The claimed invention differs from the closest analogue in that it implements complete automation of the operation process of the installation of an electric centrifugal pump with a frequency-controlled electric motor (figure 1).

SUMMARY OF THE INVENTION

The problem solved by the claimed invention is the automation of the operation of an oil well by installing an electric centrifugal pump.

The technical result of the claimed invention lies in the complete automation of the start-up process, bringing it to the technological mode and monitoring operation, which will lead to an increase in the overall reliability of equipment (ESP) and a decrease in the cost of oil production.

The technical result of the claimed invention is achieved by controlling the temperature by changing the frequency of rotation of the pump shaft, which is the first time for “feedback”, the operating temperature is taken to control the condition of the centrifugal pump, namely due to the fact that the method of operating an oil well by installing an electric centrifugal pump, in which the electric centrifugal pump (ESP) is installed in the well at a predetermined depth of the installation in the well, operation parameters are determined and entered into the control station, The operating parameters are set: the initial pressure at the pump inlet, the temperature of the initial pump, start the installation of the ESP into operation, while simultaneously recording the pressure at the inlet of the ESP, the temperature at the pump and the temperature at the inlet of the pump, while the pump is operated with an adjustable speed of the pump shaft and moreover, before starting the ESP installation, the installation is checked for leaks, the initial frequency of 50 Hz of alternating current ω _n is set, the temperature limit of the pump is set so that the temperature of the pump b It is less than the permissible temperature, they fix the current strength; the pump is operated up to a pressure at the inlet of the ESP greater than or equal to the pressure of oil saturation with gas, and when the pressure at the inlet of the ESP and the saturation pressure of oil with gas are reached, the temperature at the pump inlet and the temperature at the pump are recorded, the flow rate of the well is determined, and output to a constant mode operation of the ESP installation at a constant or growing pressure of not more than 10% at the inlet to the pump for one or more hours, record the flow rate of the well, pressure at the pump inlet, temperature at the pump inlet, tempera uru pump surface and amperage, and the temperature difference between the surface of the pump with a pump inlet temperature remains constant or decreases by an amount no more than 10% and stabilized; moreover, when the pressure at the inlet to the pump is less than the saturation pressure, and the increasing difference between the temperature on the surface of the pump and the temperature at the inlet to the pump, an increase in the well flow rate is determined and, depending on the magnitude of the increase in the flow rate of the well, the pump speed is reduced and the installation is brought to a permanent operation at a pressure at the inlet to the pump above the saturation pressure, increase the frequency of rotation of the EC shaft and determine the frequency of the alternating current and current strength, simultaneously determine the temperature of the pump, continue ESP operation with the values of the most optimal flow rate, dynamic level, installation current strength and temperature on the pump surface.

In the particular case of the implementation of the claimed technical solution, the rotational speed is reduced inversely with the value of Z, which depends on the increase in the flow rate of the well, which in turn is calculated by the formula:

Q ₁ = k (P _PL -P _Z1 ), where

k - well productivity coefficient (m3 / day ^* MPa);

P _PL - reservoir pressure, equal to the pressure at the bottom when unexploited well;

P _s1 - pressure at the bottom of the well,

wherein P _s1 = P _BX1 + P _senior where

R _I1 - pressure at the pump _inlet ;

P _st.zh - the pressure of the liquid column from the bottom of the well to the level of the receiving holes of the pump,

wherein P _{article, x} = P _vx0 , where

P _in0 - initial pump intake pressure,

determine the increase in well production by the formula:

Q ₂ = k (P _pl -P _s2 ), where

k - well productivity coefficient (m3 / day ^* MPa);

P _s2 - pressure at the bottom of the well after operation time t ₁ ,

wherein the pressure P _s1 = P _I1 + P _Art. where

R _I2 - pressure at the pump intake after operation time t ₁ ,

determine the difference in the increase in well production:

ΔQ = Q ₂ -Q ₁ = k (P _in1 -P _in2 ),

then determine the ratio of Z:

Where

Q _{, opt} - optimal well flow rate.

In the particular case of the implementation of the claimed technical solution, the operation parameters are entered into the control station:

k is the well productivity coefficient,

P _PL - initial reservoir pressure, MPa;

T _w is the operating temperature of the pump.

In the particular case of the implementation of the claimed technical solution, the installation of the electric centrifugal pump is stopped for accumulation with a decreasing pressure at the pump inlet and an increase in the temperature on the pump surface to the value of the operating temperature of the cable extension and until the pressure at the pump inlet reaches R _pr = 1.2P _n . and condition

где

Where

N _Nap.tek - the current pressure of the centrifugal pump;

- напор центробежного насоса при стандартной частоте (50 Гц) переменного тока,

- the pressure of a centrifugal pump at a standard frequency (50 Hz) of alternating current,

and when the value P _ave = _n 1,2R installation work is started in time with the accumulation values; pumping time, operating current, voltage, initial and final temperature on the pump surface.

In the particular case of the implementation of the claimed technical solution, the ESPs are selected with a head margin of 25% for the pump.

Brief Description of the Drawings

Details, features, and advantages of the present invention follow from the following description of embodiments of the claimed technical solution using the drawings, which show:

FIG. 1 - installation of an electric centrifugal pump with a frequency-controlled electric motor;

FIG. 2 is a graph of pressure changes at the pump inlet;

FIG. 3 is a graph of the temperature change of the pump over time;

FIG. 4 is a graph of the temperature of the pump over time;

FIG. 5 is a graph of the temperature of the pump over time;

FIG. 6 is a graph of engine temperature change over time;

FIG. 7 - dependence of pump temperature on current frequency.

In the figures, the numbers indicate the following positions:

1 - submersible motor; 2 - hydroprotection; 3 - centrifugal pump; 4 - pump section; 5 - pump section; 6 - temperature sensor at the pump; 7 - temperature sensor at the pump inlet; 8 - pressure sensor at the inlet to the pump; 9 - cable line; 10 - control station; 11 - tubing tubing; 12 - valve with a manometer; 13 - fountain fittings; 14 - inlet holes of a centrifugal pump.

Disclosure of invention

Installation of an electric centrifugal pump (ESP) (Fig. 1) consists of a submersible motor (1), hydraulic protection (2), a centrifugal pump (3), a pump section (4, 5), a temperature sensor on the surface of the pump (6), a temperature sensor on pump inlet (7), pressure sensor at the pump inlet (8), cable line (9), control station (10), tubing tubing (11), valves (12) with pressure gauge, fountain fittings (13), inlets (14) of the centrifugal pump.

The ESP is driven by a submersible electric motor, which is supplied with alternating current from a control station with a variable frequency of electric current via a cable line (9) and in the pump rotates centrifugal devices mounted on the shafts of the centrifugal pump and sections (4, 5), coupled to the motor shaft.

The centrifugal force created through the openings on the bottom of the pump pumps the gas-liquid mixture, transferring it from the apparatus to the apparatus and further along the tubing to the oil recovery system. The ESP is located in the production casing of the well, suspended on the tubing string, which is mounted on a fountain. Fountain fittings are hermetically connected to the oil recovery system. The cable line supplying the electric motor (9) is attached to the tubing and is connected to the control station (10) through a sealed hole on the fountain fittings.

The control station (SU) serves to start (stop), to continuously supply alternating current through the cable line to the submersible motor, to continuously monitor the insulation resistance of the cable line, to change the frequency of the alternating current, and also to receive information transmitted through the cable line from sensors (6, 7, 8).

Automatic control of the ESP is possible only through the thermal state of the centrifugal pump, so the only parameter that allows unambiguous control over the entire centrifugal installation is the rate of change of the relative temperature of the pump. The relative temperature of the pump depends on the thermal parameters of the pump, on the characteristics of the produced fluid.

The relative temperature of the pump, depending on the gas content at the pump intake, changes unambiguously - it depends on the free gas content in the gas-liquid mixture at the pump intake. The gas content at the pump intake depends on the gas factor, saturation pressure, pressure at the pump inlet, and water cut. And therefore, the relative temperature of the pump can serve as a “feedback” to automate the control of an electric centrifugal pump - the creation of unmanned technology.

The relative temperature on the surface of the pump is calculated by the formula:

Where:

ϕ - gas content in the mixture at the pump inlet, fractions of a unit; q ₀ - thermal power of the pump, kW / m ³ ; R ₂ is the radius of the outer surface of the pump housing, m .; R _I - pressure at the pump inlet, at .; P _n - pressure of oil saturation with gas, at .; B is the water content in the production of a well, a fraction of a unit h is the pressure of one pump apparatus with the corresponding gas content in the mixture, at .; G - gas factor, m3 / m3; R _at - atmospheric pressure, at .; α is the heat transfer coefficient of the mixture in the metal pump casing, W / m ^{2 *} ° C .; λ _from - the coefficient of thermal conductivity of the gas layer on the outer surface of the pump, W / m ^{2 *} ° C; δ _from - the thickness of the gas on the outer surface of the pump, m .; T _f - temperature of the mixture at the inlet of the pump, ° C; T _w is the temperature on the surface of the pump, ° C.

For well operation, it is first necessary to select the ESP installation with the optimal flow rate (flow rate), with a head margin of 25% at the pump and a depth of the installation lowering into the well.

(от 0,1 до 1 и более, в зависимости от месторождения и скважины); начальное пластовое давление - Р_пл, МПа; рабочая температура насоса - T_w.The following parameters are introduced into the control station: k - well productivity coefficient,

(from 0.1 to 1 or more, depending on the field and well); initial reservoir pressure - R _pl , MPa; pump operating temperature - T _w .

сила тока на двигателе I_p, А; напряжение тока U_д, В; напор, развиваемый установкой ЭЦН при стандартной частоте 50 Гц. - H_нап(ω); Рн - давление насыщения нефти,Permissible temperature T _{n, additional} (this temperature may be equal to the operating temperature of the cable line, for Russian cable lines less than 230 ° C), ° C; the initial frequency of the alternating current is ω _n , Hz; optimal performance of the ESP installation - Q _op (ESP performance at a frequency of ω _n = 50 Hz for Russian installations),

current strength on the motor I _p , A; voltage U _d , V; the head developed by the ESP unit at a standard frequency of 50 Hz. - H _{nap (ω)} ; Rn - oil saturation pressure,

Before starting the ESP, it is necessary to make sure that the flow line is open (gate valve 12), the direction of rotation of the unit is clockwise — the direction of pressure and rotation form the “right screw”. It is necessary to close the gate valve on the flow line (12) on the fountain valves, start the installation, build up a pressure of 40 atm. on fountain fittings and the ESP installation, turn off. The pressure on the fountain valves remains constant (pressure drop up to 38 atm is allowed within 15 minutes) - the structure is sealed. Otherwise, the structure is leaky.

Then set the initial frequency ω _n , set the limit on the temperature of the pump T _n <T _{to, add} . Temperature T _{n, add} (for example, the operating temperature of the cable line adjacent to the pump - the permissible temperature (130 ° C) is 230 ° C for Russian ESPs, (standard) heat-resistant flat part adjacent to the centrifugal pump). Start the installation of the ESP into operation, while simultaneously recording the pressure P _in at the inlet of the ESP, the temperature at the pump T _w and at the inlet to the pump T _ƒ . At the same time build a graph of the pressure at the inlet to the pump (figure 2), temperature T _w (figure 3) and the temperature at the inlet T _f . (figure 4). Before starting, the initial pressure at the pump inlet P in _{0 is fixed} , the initial temperature of the pump is T _w0 . At the same time record the value of current I.

1. The operation of the pump is carried out to the value:

2. When achieving equality:

record the temperatures T _f and T _w ., carry out the construction of graphs depending on the time P _I , T _f , T _w and current I. And, and determine the flow rate of the well Q _w0 .

3. If at the same time the pressure at the inlet to the pump remains unchanged for one or more hours or slightly increases (no more than 10%), then the process of starting the ESP installation is considered complete. In this fixed flow rate Q _g, the inlet pressure of the pump P _Rin on the pump inlet temperature T _f, the surface temperature of the pump T _w, the current strength I _p and recorded in the "current parameters" for transmission technology (geologist) Company.

4. In this case, the difference T _w -T _f remains constant or decreases by a certain amount (not more than 10%) and stabilizes.

5. If the condition T _ƒ = T _w is met when starting up the installation, then the current strength Ip is checked, and if the current strength is 0, the process of starting the installation is repeated. Otherwise, it is necessary to check the tightness of the installation.

6. When the difference (T _w -T _f ) is reduced by more than 10% due to an increase in the flow temperature at the inlet to the pump T _{f, the} operation of the centrifugal pump continues: The technologist is given the values of T _f , T _w , well flow rate Q _w , dynamic level Nd (pressure at the reception of the pump P _ol ), current I _p , voltage U _p , AC frequency.

7. If the pressure at the inlet to the pump R _I continues to fall, becoming lower than the saturation pressure P _n , so that the difference T _w -T _f will increase, then by the formula:

Q ₁ - fluid flow rate (m3 / day) at bottomhole pressure P _s1 , where k is the well productivity coefficient, m3 / day ^* MPa; P _s1 - pressure at the bottom of the well, P _{st, l} = P _in0 ., P _st. - pressure of the liquid column from the bottom of the well to the level of the pump inlet, P _in0 - _initial pressure at the pump, R _pl - reservoir pressure, equal downhole pressure with a non-operational well.

If the pressure drops during the pump run:

where Q ₂ is the fluid flow rate (m3 / day) at R _s2 is the pressure at the bottom of the well after operation, time t ₁ .

ΔQ is determined - the difference (increase in well production) between (5) and (4), we have:

8. Next, determine the ratio Z:

9. Reduce the speed of the pump shaft inversely with the value of Z:

Next, control the temperature of the pump and build graphs of dependence (figure 6).

11. Carry out a graph of dependence (figure 7) T _w = ƒ (ω).

12. Check the current pressure value of the ESP:

where: N _Nap.Tek - the current pressure head of the ESP at a frequency ω _i (i takes the values of process steps 1, 2, 3, etc.

и, проверяя выполнение условия (9) получаем, что:13. Repeating p. 6 - p. 8 i times, that is, repeat p. 6-8 until reaching

and, checking that condition (9) is satisfied, we obtain that:

where ΔT _w is the temperature change at the pump, Δω is the current frequency change.

14. Then the process of bringing the installation to a constant mode is considered complete.

15. The technologist (geologist) is transferred: a new frequency ω ₁ , a new flow rate Q ₁ , a new pressure at the pump inlet P _in1 , current I _p1 .

Periodic operation mode - IES (short-term operation of ESP)

If the pressure at the inlet to the pump drops, and the temperature of the pump rises to an acceptable value - for example, to an acceptable temperature of the cable line attached to the pump housing, and the condition:

- напор центробежного насоса при стандартной частоте (50 Гц) переменного тока. Тогда установка ЭЦН останавливается до времени t_нак - время накопления, при котором давление на приеме насоса становитсяN _Nap.Tek - current pressure,

- the pressure of a centrifugal pump at a standard frequency (50 Hz) of alternating current. Then the ESP installation stops until the time t _nk is the accumulation time at which the pressure at the pump inlet becomes

If the value P _ave = _n 1,2R installation and start the work carried plotting:

At pump temperature:

ESP installation stops at accumulation.

The technologist is given: accumulation time t _nk ; pumping time t _open , operating current I _slave , voltage U _slave , surface temperature of the pump T _{w, beginning,.} T _{w, con} (initial and final temperature at the pump).

This completes the process of bringing the ESP installation to the IES mode.

ESP installation size optimization

Often, when designing an ESP installation for a corresponding well, an error is made due to the unreliability of data for this well.

Then, after starting the ESP and putting it into continuous operation, it turns out that the pressure at the inlet to the pump P _in is higher than the saturation pressure. This means that there is an opportunity to increase oil production. To do this, increase the speed of the centrifugal pump shaft.

The calculation of the frequency of the alternating current is calculated by the formula (7):

Qzh - fluid flow rate before changing the frequency, m3 / day, ΔQ _w - fluid flow rate increase after changing the pump shaft speed, Z - dimensionless quantity

Qzh - fluid flow rate before the frequency changes, ΔQ _w - fluid flow rate change, Z - ratio.

In this case, the current strength at the installation will increase and become equal to:

I _z = Z ³ I _p

Ip is the current strength at the installation at the flow rate Qzh, Iz is the current strength after the flow rate increments by ΔQ _w , that is, it will be cubic depending on the coefficient Z.

Therefore, a further change in the frequency of the alternating current is carried out while determining the temperature of the pump T _w , so that the inequality is satisfied:

T _w ≤T _{k, add.}

This completes the process of exploring the possibility of a well, the technologist is given the parameters: the most optimal flow rate Q _W , _optim , the dynamic level N _d , the current strength at the installation I _p and the temperature on the surface of the pump T _w .

1. An example of practical application for the conclusion of the ESP installation to the operation mode.

1.1. As an example, consider well No. 236 of the N-field.

The expected flow rate of 18 m ³ / day with a dynamic level of fluid in the well (along the bore) N _d = 1600 m (vertical 1420 m). Oil gathering line pressure 14 at. The friction resistance in the tubing is assumed to be 5 at (with a friction margin, the flow rate will be 10 at). The total required head is 1900 m. Given the head margin of 25%, the necessary head is 2350 m. Based on the productivity of the well, we select the ETsN5-20-2350 installation. Let the saturation pressure be 110 atm. The gas factor is 140 m ³ / m ³ . The vertical well depth Нв = 2680 m. The oil density in the well is assumed to be equal to 752 kg / m ³ . The density of produced water is 1004 kg / m ³ , the temperature of the formation is 82 ° C, the temperature gradient along the wellbore is 0.03 ° C per 1 m of the well. Well productivity coefficient is

The optimal pressure at the pump intake P _op = P _n = 110 at. Then the height of the liquid column in the well is:

g = 9.8 m / s ²

where ρ _cm is the density of the mixture; ρ _n - oil density; ρ _in is the density of water; In - the water content in the product.

Let ρ _n - 852 kg / m3; ρ _in - 1004 kg / m3; B - 0.23

The density of the mixture: ρ _cm = (852 * (1-0.23) + 0.23 * 1004) = 656 + 231 = 887

Liquid column height:

101325 n / m ² = 1 at - conversion factor.

Taking away from the vertical depth of the borehole H _st = 1396 m, we have a vertical dynamic level:

N _dyne = N _well -H _st = 2680-1396 = 1284 m.

Or along the wellbore:

H _dyn.pstv = N _dyn + 160 = 1284 + 160 = 1444 m.

where 160 m. is determined by the well inclinometry table; N _din.pstv is the dynamic level of the well along the wellbore (production casing). The well inclinometry table is the difference between the length of the wellbore and the vertical depth (determined by the inclinometer device) and is constant for each well.

To select the depth of descent of the ESP installation, let us assume that the installation without a separator and according to the “Operational Procedure ...” used in oil production enterprises, at a pump intake, a gas content of 25% is permissible (ϕ = 0.25).

Then the gas content at the pump inlet is:

where V _in.NU - the volume of gas at the inlet to the pump under normal conditions, which is calculated by the formula:

Suppose the flow rate depends on the dynamic level proportionally and according to formula (6) we find the change in flow rate when the dynamic level changes from N _d to N _dyn .

Substituting the values, we have a change in the flow rate of the well:

ΔQ _w = 0.11 * ((1600-1444) * 852 * 9.8) / 101325 = 1.4 m3 / day

where 101325 n / m ² = 1 at. (conversion factor).

At a dynamic level of 1444 m, the flow rate will decrease by 1.4 m3 / day and amount to 16.6 m3 / day.

We calculate (19) the amount of free gas at the pump intake:

From where (20) we find the pressure at the inlet to the pump P _I :

The deepening of the ESP installation under the dynamic level will be:

The suspension depth of the ESP installation (vertical, from the wellhead) is equal to:

N _sp = 1444 + 943 = 2227 m.

Including inclinometry (according to the inclinometry table):

H _sp.pstv = 2227 + 230 = 2457 m.

(where 230 m. from the well inclinometry table)

The relative temperature of the pump during operation with a gas content of 0.25 (25%), a flow rate of 18.6 m3 / day at a dynamic level of 1444 m (with a pressure at the pump inlet of 82 atmospheres) will be equal to:

a) we calculate the relative temperature of the pump according to the formula (1)

To do this, we calculate the value of q ₀ : thermal power in the ESP units, which is spent on heat generation. For this:

a) let the rated power of the submersible motor N _nom = 16 kW, the efficiency of the entire ESP installation is η _ESP = 0.36;

But when pumping a gas-liquid mixture with a free gas content of 25% at the pump inlet, the installation efficiency drops to 0.2.

Then the amount of heat generated in the installation is:

b) calculate the number of devices in the ESP installation, it is equal to:

Of these, the number of devices pumping a highly carbonated mixture until gas is completely dissolved in oil (from an inlet pressure of 82 atm to a saturation pressure of 110 atm) is equal to:

It was suggested here that the average head in the area from 82 to 110 at. Is 0.08 at. (20% of the nominal pressure equal to 4 m.).

Assuming that the power consumption is produced uniformly on all the ESP units, (power coming to 350 pump units)

c) we find the thermal power q ₀ on 350 devices, given that the height of the device is 6 cm, diameter 10 cm and heat is distributed throughout the pump with a length of 21 m (350 devices). Then, on 350 devices, the power of the heat source is equal to:

where d is the diameter of the pump, l is the length of the pump, π = 3.14.

d) then the relative temperature (temperature increase in the pump) will be:

We calculate the absolute temperature of the pump, assuming that the geothermal coefficient is 0.03 ° C / m.

To do this, we calculate the temperature of the mixture at the pump intake, it is equal to:

Then the absolute temperature on the surface of the pump is equal to:

The temperature of 223 ° C is close to the permissible temperature (permissible 230 ° C).

The flow rate of 16.6 is not acceptable for the pump of the ETSN5-20-2350 installation, since in order to ensure such a flow it will be necessary to install a wellhead fitting on the fountain fittings of the well, which leads to an unproductive expenditure of electricity in the installation. Therefore, we further define the relation:

Reduce the frequency of the alternating current by a submersible motor by a factor of Z.

The frequency is:

Then the installation flow will be equal to 16.6 m3 / day. Installation head will decrease to:

Head balance: 1632 m. = 1444 m. + 50 m. + 138 m.

The total required head of 1900 m, obviously, the installation head of 1632 m is not enough, therefore, a further decrease in the frequency of the alternating current is unacceptable. We calculate the change in the temperature of the pump with a decrease in the frequency of the alternating current. Power consumption will decrease to:

The power of the heat source is equal to:

Then the power of the heat source in the pump according to (35) is equal to:

The absolute temperature of the pump is:

еслиComparing the thermometer (6) and (8), we find the difference

if

with an accuracy of ± 5%, then the process of entering the technological mode of operation is considered complete.

Periodic operation mode:

If during operation of the ESP unit the relative temperature of the pump will increase, so that the head of the unit will become lower than the necessary head:

where N _p - the working pressure of a centrifugal pump, P _I - pressure at the inlet to the pump, N _b - pressure in the oil recovery system. In this case, it is necessary to turn off the ESP installation, build a graph of the dependence of P _in on time. Determine the time T _nak . accumulation of liquid in the well to a pressure value at the inlet P _in = P _n . We start the installation in operation to the temperature of the pump T _w ≤T _add , at the same time take into account the operating time of the installation T _p . At the same time, we register the current strength at the beginning of pumping I _n and I _k , determine the well flow rate at the initial moment Q _n and before switching off Q _k (final flow rate value). We calculate the volume of pumped liquid as the arithmetic mean:

We give the plant’s technologist operating parameters of the installation: volume of produced fluid Q; installation operating time T _r ; the accumulation time (downtime) of the installation T _n

All technological parameters are transferred to the technologist (geologist) of the enterprise.

Optimization mode.

If after starting up the unit in operation, the pressure at the inlet to the pump becomes constant and greater than the saturation pressure, then it is necessary to determine the additional flow rate of the well by the formula:

We calculate the change in the frequency of rotation of the pump shaft (AC frequency) according to the formula:

We increase the frequency of the current from 50 Hz to 50Z, determine the relative temperature, if it is not higher than the permissible T _{n, add.} , step by step, increase the speed:

With a further decrease in the pressure at the inlet of the pump P _in, planning increases the frequency of the alternating current based on (1).

All technological parameters are transferred to the technologist (geologist) of the enterprise.

Scale warning mode.

To do this, reduce the temperature of the pump to the start of scale T _salt .

And the entire process of entering the mode is carried out in accordance with clause 9.1, 9.2, 9.3.

For example, if the relative temperature of the start of scaling at the well is 46 ° C, then T _{n, add} = 46 ° C.

All technological parameters are transferred to the technologist (geologist) of the enterprise.

Claims (47)

1. A method of operating an oil well by installing an electric centrifugal pump, in which install in the well an electric centrifugal pump (ESP) at a predetermined depth of the installation in the well, work parameters are determined and entered into the control station, fix operation parameters: initial pressure at the pump inlet, initial pump temperature, start the installation of the ESP into operation, while simultaneously recording the pressure at the inlet of the ESP, the temperature at the pump and the temperature at the inlet to the pump, while operating the pump is carried out with an adjustable speed of the pump shaft, characterized in that before starting the ESP installation, the installation is checked for leaks, set the initial frequency of 50 Hz AC ω _n , set a limit on the temperature of the pump so that the temperature of the pump is less than the allowable temperature, fix current strength; operation of the pump is carried out to a pressure at the inlet of the ESP equal to or greater than the pressure of oil saturation with gas, and when the pressure at the inlet of the ESP and the saturation pressure of oil with gas are reached, the temperature at the pump inlet and the temperature at the pump are recorded, determine the flow rate of the well and bring the ESP unit to continuous operation at a constant or growing pressure of not more than 10% at the pump inlet for one or more hours, record the flow rate of the well, pressure at the pump inlet, temperature at the pump inlet, temperature at the surface of the pump and amperage, the temperature difference on the surface of the pump with the temperature at the inlet of the pump remains constant or decreases by no more than 10% and stabilizes; moreover, when the pressure at the inlet to the pump is less than the saturation pressure and the increasing difference in temperature on the surface of the pump and the temperature at the inlet to the pump, an increase in the well rate is determined and, depending on the magnitude of the increase in the well rate, the pump speed is reduced, and bring the installation to a constant mode of operation, and at a pressure at the inlet to the pump above the saturation pressure, increase the frequency of rotation of the EC shaft and they determine the frequency of the alternating current and the current strength, at the same time determine the temperature of the pump, continue to operate the ESP with the values of the most optimal flow rate, dynamic level, installation current strength and temperature on the pump surface. 2. The method according to p. 1, characterized in that the rotational speed is reduced inversely with the value of Z, depending on the increase in well production, which in turn is calculated by the formula: Q ₁ = k (P _PL -P _Z1 ), where k - well productivity coefficient (m ³ / (day⋅MPa)); P _PL - reservoir pressure, equal to the pressure at the bottom when unexploited well; P _s1 - pressure at the bottom of the well, wherein P = _P1 + P R _{INP1 st.zh.} where R _I1 - pressure at the pump _inlet ; P _st.zh - the pressure of the liquid column from the bottom of the well to the level of the receiving holes of the pump, wherein P _{article, x} = P _vx0 , where P _in0 - initial pump intake pressure, determine the increase in well production by the formula: Q ₂ = k (P _pl -P _s2 ), where k - well productivity coefficient (m ³ / (day⋅MPa)); P _s2 - pressure at the bottom of the well after operation time t ₁ , wherein the pressure P _s1 = P _I1 + P _Art. where R _I2 - pressure at the pump intake after operation time t ₁ , determine the difference in the increase in well production: ΔQ = Q ₂ -Q ₁ = k (P _in1 -P _in2 ), then determine the ratio of Z:

Where Q _opt - optimal well production. 3. The method according to p. 1, characterized in that the operation parameters are entered into the control station: k - well productivity coefficient, m ³ / (day⋅MPa); P _PL - initial reservoir pressure, MPa; T _w is the operating temperature of the pump. 4. The method according to p. 1, characterized in that the installation of the electric centrifugal pump is stopped for accumulation with decreasing pressure at the pump inlet and increasing the temperature on the pump surface to the value of the operating temperature of the cable extension and until the pressure at the pump inlet P _r = 1 is reached, 2P _n . and condition

Where N _Nap.tek - the current pressure of the centrifugal pump;

- the pressure of a centrifugal pump at a standard frequency (50 Hz) of alternating current, and when the value P _ave = _n 1,2R installation work is started in time with the accumulation values; pumping time, operating current, voltage, initial and final temperature on the pump surface. 5. The method according to p. 1, characterized in that the ESP is selected with a head margin of 25% for the pump.

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