RU2352768C2 - Power consumption minimisation method while ensuring given liquid rate and associated control unit - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: power consumption minimisation method is intended for ensuring the given liquid rate by selecting pump with maximum allowable capacity. Upon equipment installation, the pump is switched on and reference liquid pumping is performed. The real capacity of installed equipment is measured during the reference pumping by measuring unit and required value of operation factor is derived as the given liquid rate ratio to the measured capacity. Pumping is terminated at maximum equipment parameters, for example, motor underloading. When equipment is off line, pressure recovery curve is measured. Based on the above curve and given liquid rate, maximum allowable period of equipment outage is defined. The derived value is input to the equipment operation program. The equipment is actuated cyclically in the normal mode of operation. Under normal conditions, the current rate and operation factor value are measured in each cycle as a relation of cyclic operation time and to the cycle period. Then, the value is compared with the given value and maintained at the same level by controlling filling interval increase or decrease depending on the current operation factor increase or decrease by means of control unit. The complete control unit contains switch with its input 1 being connected with power network and input 2 with control unit output. The switch output is connected with pump drive power bus and measuring unit input. The measuring unit output is coupled with control unit input. Input/output port of control unit is linked with i/o port of regulator unit through the modem 1, communication unit and modem 2.

EFFECT: reduced load to pump motor under minimum power consumption and the given liquid rate.

4 cl, 4 dwg, 2 tbl

Description

1. The technical field

The invention relates to the field of production of liquid minerals, mainly in the oil industry, and can be used in deep-pump operation, in particular, oil wells.

2. The level of technology

A known method of oil production, in which a pump is selected with a capacity corresponding to the maximum oil inflow rate for a given well, and the engine speed is controlled so that the fluid outflow is equal to its maximum inflow. As a result, there is a continuous, uniform process of pumping liquid. According to this method, the power of the pumping unit is uniquely determined by the flow rate, respectively, the energy consumption is fixed (RF patent No. 2280151, IPC EV 43/12).

The disadvantage of this method is the lack of opportunities for saving energy consumed during the operation of the pumping unit.

Known methods that implement a cyclic mode of operation. These include the well fluid production method adopted in the method part for the closest analogue, in which the downhole pumping equipment is placed at a rational depth and the fluid is pumped to the oil recovery system by a pump, with the possibility of its operation in the cyclic mode of regular fluid production, with the choice of a pump for pumping power П1 >> П2, where П1 - nominal pump capacity; P2 - the expected flow rate of the liquid (RF patent No. 2190087, IPC 7 EV 43/00).

The disadvantage of this method is that it does not provide the ability to obtain a given flow rate with a minimum energy consumption. The method involves optimization of a set of parameters only the flow rate. The list of parameters by which optimization is carried out in a known technical solution does not include energy consumption for raising a liquid.

In terms of the device, the complete SHGS5805-IE device (AREZh. 656427.001 TU, Moscow, 2004), which includes a key 1, a control unit 3, is taken as the closest analogue, the first input of key 1 being connected to the power supply network, the second input to the output of control unit 3 The output of key 1 is connected to the power supply bus of the pump electric drive and the input of the meter unit 2. The output of block 2 is connected to the input of the control unit 3.

The disadvantage of this device is that it does not provide automatic control parameters, at which a given flow rate is realized with minimal energy consumption.

3. The invention

3.1. A task

The technical problem is to minimize energy consumption while ensuring a given flow rate.

The technical result consists in the possibility of obtaining a given flow rate with minimal energy consumption.

3.2. List of drawings

Figure 1 presents the timing diagram of the equipment during cyclic operation.

Figure 2 shows the pressure recovery curve characterizing the process of filling the well after pumping out the liquid and turning off the pumping equipment.

Figure 3 shows the dependence of the average fluid flow rate on the downtime of pumping equipment in a cyclic mode of operation.

Figure 4 presents a block diagram of a control device, where: 1 - key, 2 - meter unit, 3 - control unit, 4 - first modem, 5 - communication channel, 6 - second modem, 7 - controller block.

3.3. Features

The method, in contrast to the known method, includes the following operations.

Pumping equipment is selected with the maximum permissible performance, after installing the equipment at a rational depth, turn it on and carry out a control pumping of the liquid, during the control pumping process, measure the real productivity of the installed equipment and the required value of the operating coefficient as the ratio of the set flow rate to the measured capacity, the pumping process is completed by boundary parameters equipment, when the equipment is off, measure the pressure recovery curve, according to Ora and specified production rate determines the maximum possible downtime; this value is entered into the equipment operation program, then the equipment is launched into regular operation in a cyclic mode, during normal operation in each cycle, the current value of the operating coefficient is measured as the ratio of the operating time in the cycle to the cycle duration, the obtained value is compared with the required value and maintained flow rate at a given level by adjusting the downtime of the equipment (filling interval) in the direction of decreasing or increasing depending on the decrease or increase in tech at the same time, the downhole pumping equipment is placed at a rational depth in terms of the rate of restoration of fluid pressure in the well equal to or greater than the required flow rate, and the completion of the pumping process can be carried out by reducing the amount of current consumed by the engine to the lower tolerance limit (signal underloading).

The device, in contrast to the known one, contains the first and second modems, a communication channel and a controller unit, the input / output port of the control unit through the first modem, a communication channel and a second modem being connected to the input / output port of the controller unit.

The essence of the proposed method is as follows.

Choose the type of pumping equipment with the lowest specific energy consumption per unit volume of the liquid to be lifted, and also minimize the load on the pumping equipment engine within acceptable limits. The type of pumping equipment is selected based on the task for the fluid flow rate and taking into account the fact that with an increase in the productivity of the equipment, the specific energy consumption for pumping out a cubic meter of fluid is reduced. This position is illustrated by table 1, which summarizes the reference data on the performance of various pumping units (column 2), energy costs (column 4) and the calculated specific energy consumption per cubic meter of the product to be lifted (column 5).

Table 1 one 2 3 four 5 type of instalation Productivity (cubic meters) engine's type Power consumption kW / h Specific energy consumption kW / h per cubic meter per day in hour UVNN5-44-2100 / 00-003- 44 1.83 PEDN32 117-1000-03 32 kWh 17.4 (100%) UVNN5-59-2100 / 00-003- 59 2.45 PEDN40 117-1250-03 40 kWh 16.3 (93%) UVNN5-79-2100 / 00-003- 79 3.29 PEDN56 117-1400-03 56 kWh 17 (97%) UVNN5-125-2100 / 00-003- 125 5.2 PEDN80 117-2100-03 80 kWh 15.3 (87%)

Minimization of energy consumption is carried out by the choice of equipment that maximally exceeds a given flow rate. To the maximum, productivity is limited by the acceptability of the technical and economic characteristics of the equipment (since with an increase in the productivity of the installation, its size and cost increase).

The choice is made according to the passport data of the plants (for example, for pumping 40 cubic meters of liquid per day, they choose a plant with a capacity of 125 cubic meters per day, which reduces energy costs by 13%, table 1).

The rating performance of the installation may differ from the real one due to differences in the density of the test fluid and the fluid in a particular well.

To determine the real performance carry out a control pumping liquid. In the process of control pumping, the actual pump performance is measured in specific well conditions. The measurement is carried out by one of the known methods (for example, by measuring the time it takes to fill a measuring tank).

The pumping process is completed by automatically turning off the equipment according to its boundary parameters, for example, by reducing the motor current to the lower tolerance limit (underload).

The load on the engine during the cyclic production mode is estimated not only by the volume of the liquid being lifted, but also the effect on the pump of the liquid column in the annulus is taken into account. In the filling time interval (when the equipment is idle), a column of liquid (“backwater”) accumulates in the annulus, the pressure of which, according to the law of communicating vessels, facilitates the subsequent rise of liquid in the pump pipe. This reduces the load on the pump motor and, accordingly, reduces energy consumption, and the higher the pressure of the liquid column, the lower the load.

The minimization of energy consumption is achieved by providing the maximum allowable pressure of the liquid column. This pressure is realized by assigning the maximum allowable value for the idle interval of the pumping equipment in a cyclic mode (Tpr, Fig. 1).

The maximum allowable downtime is assigned using the pressure recovery curve (Fig. 2), which characterizes the process of filling the well after pumping out the liquid and turning off the pumping equipment. The course of the curve is explained as follows. When the fluid from the well is pumped to the minimum acceptable level (point "O" on the curve of figure 2), then at the beginning of the filling interval, the flow rate is maximum. Over time, the pressure of the liquid column balances the reservoir pressure, the flow decreases and slows down. If the pumping equipment is not switched on, then the flow will cease altogether.

The nature of the curve is well approximated by the relative expression:

P = 1-E ^-T ,

where P is the liquid column pressure, T is the time in hours (and minutes).

The steepness of the curve is different for different wells, but the nature of the curve is preserved. The initial portion of the curve (OA) corresponds to the maximum filling rate. Further, growth slows down (sections AB, BC), and then stops altogether. Point “O” (time T0) corresponds to the pressure at the installation point of the pumping equipment.

The calculated graph of the average speed versus downtime (actually averaging time) is presented in FIG. 3. The average speed is given in relative units - relative to the maximum speed in the initial section of the curve.

The pressure recovery curve is measured after the end of the control pumpdown process and the equipment is turned off. The measurement is carried out, for example, using industrial means of immersion telemetry. A real example of the data obtained is shown in table 2. The actual pressure recovery curve is shown in figure 2.

table 2 min 60 120 180 240 300 360 420 480 540 Tpr hour (i) 0 one 2 3 four 5 6 7 8 Pi tons 44.2 70.7 92 107.5 120.3 130.8 139.7 147 151.7 P - P0 tons 25.8 47.8 63.3 76.1 86.6 95.5 102.8 107.5 (Pi-P0) / T (i) 25.8 23.9 21.1 19.0 17.3 15.9 14.6 13.4 % one hundred 92 82 74 67 61 56 52

The maximum allowable idle value corresponds to such a point on the curve of figure 2, in which the average speed of the curve characterizing the flow rate decreases below the allowable value (below the dashed line in figure 3). For example, this is point “A” in FIG. 2 (downtime interval T0-T1). If the interval value is reduced, the flow rate will not decrease, and the maximum column height will decrease. If the interval value is increased, then the column height will increase, but the flow rate will decrease, which is unacceptable under operating conditions.

The pumping time (equipment operating time) during operation is set automatically depending on the performance of the selected pumping equipment. Since a considerable column of liquid accumulates in the annulus during downtime, the pump operates at its rated capacity. The evacuation time of the column depends on the ratio of pump capacity and fluid flow rate.

The higher this ratio, the higher the relative pumping speed, and the shorter the required pump run time relative to the fill time. The ratio for a given calendar period (for example, per day) characterizes the coefficient of equipment operation.

With a known and constant pump capacity, the operating coefficient characterizes the flow rate. The ratio of the set flow rate to the measured value of the pump capacity determines the required value of the coefficient of operation Kt.

Current control of the flow rate is as follows. According to established practice, the flow rate is measured over a sufficiently long period of calendar time (day, month, etc.). Long intervals are taken to ensure accuracy, which meets the commercial and technological control objectives. However, such control is not operational and does not provide a sufficiently fast response during regulation.

According to the proposed method, to achieve the efficiency of regulation, the flow rate control is carried out with maximum speed - during each cycle (minimum allowable time).

The control is carried out by measuring the ratio of the operating time Tr in the next cycle to the duration of this cycle TC (figure 1). This ratio characterizes the current (in contrast to the calendar) real value of the coefficient of exploitation of Kr in a given cycle.

Obtaining a given flow rate is realized using the setting processes and subsequent regular work.

The setup process determines the initial downtime of the equipment. If the equipment includes immersion telemetry, then, knowing the required flow rate, the initial value is determined by the pressure recovery curve (figure 2, 3 or table 2). For example, this is the interval T0-T1.

In the absence of submersible telemetry devices in the equipment, the value of the initial interval is set so that the value of Kp is less than the value of Kt (the inflow rate is higher than or equal to the required value), then the idle time interval Tpr is gradually increased until the value of Kp exceeds the value of Kt. In this case, the flow rate begins to decrease and corresponds to the speed at point "A" in the curve of figure 2.

The resulting downtime is entered into the equipment work program and then the equipment is started up in a regular operation in a cyclic mode.

In the process of regular work in each working cycle (Fig. 1), its parameters are measured - the operating time Tr and the duration of the cycle TC. According to the measurement results, the real current value of the operating coefficient of the CR is calculated and compared with the required value of CT.

If there are significant deviations, the flow rate is set at a predetermined level by controlling the filling interval, decreasing it if the flow rate is less than the specified one, or by increasing the interval if the flow rate exceeds a predetermined value.

As a result, minimization of energy consumption is ensured by:

- use of pumping equipment with the maximum permissible performance with the lowest specific energy consumption per cubic meter of pumped liquid;

- ensuring the maximum allowable pressure of the liquid column filling the annulus;

- increasing the density of the liquid in the annulus due to degassing, which contributes to an increase in the pressure of the liquid column and to reduce the load on the engine.

A real reduction in energy consumption is confirmed in practice. So, in the field of one of the oil and gas companies, the application of the proposed method has led to a reduction in energy costs up to 40%.

The advantage of this method is the ability to obtain a given flow rate of the liquid with a significant reduction in energy costs. The method is simple and convenient to operate.

The method is implemented using the device, which includes: key 1, meter unit 2, control unit 3, first and second modems 4 and 6, communication channel 5 and controller unit 7. The first input of key 1 is connected to the power supply network, the second input is with the output of the control unit 3. The output of key 1 is connected to the power supply bus of the pump electric drive and the input of the meter unit 2. The output of block 2 is connected to the input of the control unit 3. The input-output port of control unit 3 is through the first modem 4, communication channel 5, and second modem 6 connected to the input / output port of the regulator block 7.

Key 1 carries out the switching of the voltage of the power network and provides switching on and off the power of the pumping equipment motor upon command from the control unit 3.

The meter unit 2 monitors the status of pumping equipment (on / off) by measuring and analog-to-digital conversion of the current consumed by the motor, as well as monitoring the pressure at the pump intake according to the data received from the submersible telemetry equipment, if pumping equipment is equipped with it. Data from submersible telemetry devices is received through the power line of the pump motor.

The control unit 3 implements the cyclic mode of operation of the pumping equipment, while controlling the operation of the key 1, conducts information exchange with the regulator unit 7 via the communication channel 5 through modems 4 and 6. Based on the results of the information exchange, sets the parameters of the downhole equipment operation cycle and corrects their values.

The first modem 4 performs physical and logical pairing of the control unit 3 with the communication channel 5.

Communication channel 5 provides two-way digital messaging between blocks 3 and 7 through modems 4 and 6.

The second modem 6 performs physical and logical pairing of the regulator unit 7 with the communication channel 5.

The block of the regulator 7 controls the parameters of the cycle to maintain a given flow rate with minimal energy consumption. Regulation is based on the results of processing data regularly received from the control unit 3.

The device operates as follows.

Prior to the start of the working process, data on the actual productivity of the pumping equipment and the specified flow rate of the liquid are introduced into the regulator unit 7. According to these data, the unit calculates the value of the required operating coefficient Kt. If the pumping equipment does not include immersion telemetry, then the initial value of the idle time is also entered into the memory of the regulator block. The value of the initial interval is assigned so that the value of Kp was less than the value of KT (the flow rate is higher or equal to the required).

At the beginning of the working process, unit 7 requests and receives information on the status of pumping equipment from unit 3. Next, it turns on the equipment (if it was turned off) and, upon an operator’s command, starts the process of control pumping out the liquid.

After pumping is completed (receiving from the unit 3 a signal to shut down the equipment due to underload), the unit automatically periodically requests and receives data on the pressure at the pump inlet automatically. The interval between information exchanges depends on the rate of receipt of data from submersible telemetry equipment and is, for example, 10-15 minutes.

In the process of obtaining data, it calculates the differences between each subsequent and previous samples of the parameter values, compares the differences and measures the time to the current sample. Based on the calculated differences, it determines the point at which the difference decreases below a predetermined allowable value, and fixes the time of this reference. This time corresponds to the initial value of the idle interval.

Next, the controller unit 7 transmits through the communication channel 5 the initial value of the idle time Tpr to the control unit 3, which uses it as an adjustable parameter of the cycle. The transferred idle time is used by block 3 before updating (correction). The fact of receiving data, the control unit 3 confirms the transmission of the receipt.

After receiving the receipt, controller 7 sends a command to unit 3 to start the equipment in normal operation in cyclic mode and then monitors the parameters of the cycle. In the control process, the controller requests and receives from unit 3 data on the status of the equipment (on / off) and measures the operating time of the equipment Tr and the total cycle time TC (Fig. 1).

At the end of each cycle, the controller 7 calculates the real value of the operating coefficient Kp as the ratio Kp = Tp / Tc and compares it with the value of Kt.

If the difference Kr-CT is lower than the permissible value, then the downtime (Tpr, Fig. 1) does not change the controller. If the difference is higher than the tolerance, then, depending on the sign of the difference, the controller reduces or increases the downtime and transfers the changed value to the control unit 3, which updates its value in the memory. The controller will reduce the downtime with a positive sign of the difference (decrease in flow rate). Increase - with a negative sign (flow rate increased).

In the absence of means of immersion telemetry, the initial value of the idle time, which was previously entered into the controller's memory, is read from the controller's memory. Further, the controller unit 7 transmits this value via the communication channel to the control unit 3, which uses it as an adjustable parameter of the idle cycle-time Tpr. The fact of receiving data, the control unit 3 confirms the transmission of the receipt. Further, the initial value from cycle to cycle is gradually increased until the value of Кр does not exceed the value of Кт. In this situation, the flow rate corresponds to the speed at point "A" in the curve of figure 2. Further, the control process corresponds to the process described above.

The device is implemented using known technical means.

Blocks 1, 2 and 3 are implemented using the device complete SHGS 5805 IE or its modifications. Key 1 is implemented using power relays, transistor switches and thyristor regulators (to ensure a "smooth" engine start). The meter unit 2 is implemented using current transformers and conventional digital logic and converting microcircuits. The control unit 3 is implemented using a standard microcontroller (for example, a PIK processor or similar), the controller unit 7 is implemented, for example, on the basis of standard single-board computers. The implementation of the communication channel 5 depends on the territorial location of the complete control device and controller 7. To organize the channel, wired or wireless communication lines with one of the standard interfaces and interaction protocols can be used. The implementation of the first and second modems 4 and 6 depends on the selected type of channel 5. These can be interface nodes (for example, RS-232 or 485), radio modems, etc.

Claims (4)

1. A method of minimizing energy consumption, in which, to ensure a given flow rate, deep-well pumping equipment is placed at a rational depth and the fluid is pumped to the oil recovery system by a pump with the possibility of its operation in the cyclic mode of regular fluid production, with the choice of a pump for pumping capacity
P1 >> P2,
where P1 is the rated capacity of the pump;
P2 - the expected flow rate of the liquid,
characterized in that they select the pump with the maximum allowable capacity, turn it on after installing the equipment and carry out a control pumping of the liquid, during the control pumping process, measure the actual performance of the installed equipment and the required value of the operating coefficient as the ratio of the set flow rate to the measured capacity, the pumping process is completed by boundary parameters equipment, with the equipment turned off, measure the pressure recovery curve; by which and a given flow rate determine the maximum allowable downtime of the equipment; this value is entered into the equipment operation program, then the equipment is launched into regular operation in a cyclic mode, during normal operation in each cycle, the current value of the operating coefficient is measured as the ratio of the operating time in the cycle to the duration of the cycle, the obtained value is compared with the required value, and maintain the flow rate at a predetermined level by adjusting the filling interval in the direction of decreasing or increasing depending on the decrease or increase in the current coefficient of operation . 2. The method according to claim 1, characterized in that the deep-pumping equipment is placed at a rational depth in terms of the rate of restoration of fluid pressure in the well equal to or greater than the required flow rate. 3. The method according to claim 1, characterized in that the liquid pumping process is completed by reducing the magnitude of the motor current to the lower limit of the underload tolerance. 4. A control device for implementing a method of minimizing energy consumption, including a complete device consisting of a key, a meter unit, a control unit, the first key input connected to the power supply network, the second input to the control unit output, the key output connected to the power supply bus the pump and the input of the meter unit, the output of the meter unit is connected to the input of the control unit, characterized in that it contains the first and second modems, a communication channel and a regulator unit, the input / output port of the control unit Communication through the first modem, the communication channel and the second modem are connected to the input port of the output of the controller block.

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