RU2521721C1 - Measuring method of component-by-component flow rate of gas-liquid mixture - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: measuring method of component-by-component flow rate of gas-liquid mixture involves measurement of volumetric flow rate and transfer of data to a computer. Rotor rotation frequency is maintained at zero differential pressure on it; rotor torque moment values, values of its rotation frequency and viscosity of the mixture are measured; density of the mixture is determined as per the torque moment value and it is compared to one of the two known equations combining density, viscosity and component-by-component fractions of a three-component mixture; measured mixture viscosity coefficient is compared to the other of the two known equations; mass and volumetric component-by-component parts of the mixture are removed by the computer from three independent equations.

EFFECT: simplifying a measuring method of component-by-component flow rate of a gas-liquid mixture at restricted instrument composition of measuring devices; reducing the number of measurement operations requiring simultaneity for more reliable measurement of mass flow rate of medium; measuring flow parameters in one instrument place.

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Description

The invention relates to measuring technique and can be used to control the flow of gas-liquid mixture (GHS), extracted, for example, from a borehole.

Known methods for measuring multiphase flow rate or multicomponent substances, for example (P.P. Kremlevsky. Flowmeters and counters of the amount of substance. St. Petersburg Polytechnic. 2002. Book 2, p.245), using several sequentially installed flowmeters with selective properties (Coriolis, volumetric and thermal), and a computing device that determines the costs of individual components based on instrument readings.

The disadvantages of the known solutions is the total large error in the measurement of flow, as well as the presence of a variety of devices and large dimensions of the device.

A known method of component-wise measurement of multiphase flow rate (RU 2428662 C2, 09/10/2011). The proposed flow meter contains: a unit for measuring the velocity of a gas-liquid two-phase three-component flow, a unit for measuring the density of a given stream and a unit for calculating the flow rate of each phase, the unit for measuring the density comprising a mixed liquid extraction unit, the mixed liquid extraction unit comprising a pressure differential generator installed in the pipeline, through which a three-component stream passes, a pair of connecting pipes connected to the upstream and downstream sides of the gene pressure difference operators. The gas-liquid recovery tank serves as a place where it is forcibly mixed by changing the pressure between the inlet and outlet sides of the nozzle (differential pressure generator). That is, part of the selected three-phase flow is shaken forcibly horizontally, vertically, etc. for mixing. In this case, the bubbles contained in the mixed liquid grow into larger bubbles as a result of collision with each other and are separated from the mixed liquid in the gas phase. Due to forced mixing, even in the case of small bubbles, the bubbles are separated from the mixed liquid in the gas phase. Next, the mixed liquid from which the bubbles were separated is accumulated in the liquid storage tank by adjusting the valve for controlling the flow rate of the liquid. The mixed liquid accumulated in the liquid storage tank is used for density measurement. The density measurement is carried out on a mixed liquid from which the bubbles were removed, and therefore it is possible to obtain a measured value of high accuracy.

The disadvantages of this method is the large number of mechanical operations in determining the flux density, a portion of the flow is selected for analysis, reducing the reliability of the measurement of the entire flow, large dimensions of the device when standing for separation of the phases.

A known method for determining the flow parameters of a multiphase mixture of liquid and gas (RU 2386930 C2, 06.27.2009). Sensors having various dependencies of indications on the flow components of the flow are placed in the measuring hydrochannel. To obtain the dependences of the sensor readings on the measured flow parameters during calibration, the sensor readings are recorded for various combinations of liquid and gas flow rates and sequential interpolation is performed. Three sensors are used to determine the flow rates of two mutually insoluble liquids and a gas stream of a three-component mixture, the readings of which are different from the flow rates of liquids and gas. To determine the flow rates of two mutually insoluble liquids, the gas flow rate and the viscosity of the ternary mixture stream, four sensors are used, the dependence of the readings of which on the flow rates of liquids, gas and viscosity is different. In the particular case of the same type of sensors are located in series-connected segments of the measuring hydrochannel of different diameters.

The disadvantage of this method is the determination of parameters according to calibration data previously obtained at the stands. Actual readings may differ significantly from those obtained in laboratory conditions due to differences in readings on the pressure in the pipe, temperature, various combinations and the ratio of the phases of the flow, which impairs the accuracy of measuring phase velocities, their sliding relative to each other, etc.

To the proposed method, the closest adopted for the prototype is a method for measuring the component flow rate of a gas-liquid mixture passing through a pipeline using a component-based flow meter for a gas-liquid mixture containing a flow preparation unit, a liquid phase radio wave sensor, a flow meter with a differential pressure meter a mechanical measuring element associated with the calculator, and a density meter (RU No.2008617 C1, 02.28.1994).

The disadvantage of this method is the measurement of component flow rate using a vortex flowmeter having an insufficient measurement range in the conditions of cluster arrangement of wells with different flow rates, insufficient measurement accuracy, a complex signal conversion circuit characterizing the current flow rate. In addition, the vortex flowmeter has a limited minimum flow rate, less than which the flowmeter does not work, as well as the associated pipe diameter restriction. In addition, in this known method, the measurement of flow by a vortex flowmeter, despite the presence of a stirrer, needs to be reconstructed to measure Karman vortices at different phases — light and heavy, which are present in the pipeline during the flow rate of the well. Not all vortices of different intensities of different phases fall into the measurement field.

In addition, the flow preparation unit in the known method mixes all the components into a single GLC mass and only after that begins a measurement that determines the composition by the average values of the mixture flow, while the composition of the mixture is distorted, and the physical phenomenon of the components sliding between themselves disappears.

The presence of a heater in the poorly streamlined body of the vortex flowmeter changes the physical picture of the flow around the sensitive element and complicates the measuring circuit.

The technical result of the invention is to simplify the method of measuring the component flow rate of a gas-liquid mixture with a limited instrumentation of measurement devices, i.e. reduction of measurement operations requiring simultaneity for a more reliable measurement of the mass flow rate of the medium, as well as measurement of flow parameters in one instrument place.

The technical result is achieved by the fact that a method for measuring the component flow rate of a gas-liquid mixture is proposed, including measuring the volumetric flow rate and transmitting data to a computer, characterized in that the rotor speed is maintained at zero pressure drop, the rotor torque, its rotational speed and the viscosity of the mixture are measured , determine the density of the mixture by the magnitude of the torque and equate it to one of two well-known equations relating the density, viscosity and component parts of component mixture, the measured viscosity coefficient of the mixture is compared with the other of the two known equations, the mass and volume component components of the mixture are extracted from the three independent equations by the calculator.

According to the proposed method, a pressure differential of zero is maintained on the measuring device of a volumetric flowmeter in the form of a rotor, which allows not to distort and deform the flow of the stream, not to disturb its structure with sliding effects between the phases, not to compress and expand it, as occurs in most analogues using differential density meters, such as a venturi.

The drawing shows a diagram of a device that implements the proposed method.

The rotary rotor 1 of the volumetric flowmeter 2 is driven by a drive 3, the rotational speed of which is measured by the sensor 4. The volumetric flow rate of the mixture Q _{cm is} fed to the input of the flowmeter 2 and passes through the rotating rotor 1 to output 5 and then passes through a set of disks 6 rotating at a constant frequency drive 7. The viscosity of the mixture is measured by a viscosity sensor 8 and transmitted to the calculator 9. The rotational speed n of the rotor 1 is supported by the control circuit at ∆Р≈0, consisting of a differential pressure sensor 10, the calculator 9 and the drive 3. Torque The _centimeter M _{cm of the} rotor 1 of the drive 3 is measured by a torque sensor (current I _cm ) 11.

The method is implemented according to the algorithm under the following conditions:

- the pressure drop across the rotor (measuring device) is maintained equal to zero,

- temperature and pressure are measured by appropriate sensors (not shown in the drawing) for the measured flow rate at a given location and transmitted to the calculator.

The volume flow Q _{cm of the} GHS of the flow meter is determined by the rotational speed n of the rotor 1 (sensor 3)

$$Q_{\mathrm{from}m}={\mathrm{to}}_{\mathrm{one}}n,gde{\mathrm{to}}_{\mathrm{one}}-R\mathrm{but}smeRns\mathrm{th}\mathrm{to}\mathrm{about}\mathrm{uh}ff\mathrm{and}c\mathrm{and}ent.\left(\mathrm{one}\right)$$

The torque M _{cm of the} drive 3 of the rotor 1 to overcome the hydraulic resistance forces is determined mainly by the density of the mixture. Other resistance forces on the rotor are not taken into account in component analysis.

When the rotor rotates with a frequency n and a pressure drop ΔР≈0 in the measuring section 4, including rotor 1, the hydraulic resistance can be expressed as $$M_{\mathrm{from}m}=k_2{G}_{\mathrm{from}m}n=k_2{Q}_{\mathrm{from}m}{\rho }_{\mathrm{from}m}n=k_3{\rho }_{\mathrm{from}m}{n}^2,\left(2\right)$$

k ₂ , k ₃ - constant dimensional coefficients.

We define the density of the mixture as ρ _cm = M _cm / k ₃ n ² .

The values of n, M _cm , μ _cm are measured by sensors 4, 11 and 8 at ∆Р≈0, G _cm is the mass flow rate of the mixture.

The expression of the density and viscosity of the mixture through the component-wise components of the mass and volume flow rate of the mixture is known

$${\rho }_{\mathrm{from}m}=\left(G_n{\rho }_n+G_{\mathrm{at}}{\rho }_{\mathrm{at}}+G_g{\rho }_g\right)/G_{\mathrm{from}m}\mathrm{and}{\rho }_{\mathrm{from}m}={\alpha }_n{\rho }_n+{\alpha }_{\mathrm{at}}{\rho }_{\mathrm{at}}+{\alpha }_g{\rho }_g\left(3\right)$$

$${\mu }_{\mathrm{from}m}=\mathrm{one}/\left[\left(G_n/{\mu }_n\right)+\left(G_{\mathrm{at}}/{\mu }_{\mathrm{at}}\right)+\left(G_g/{\mu }_g\right)\right]\mathrm{and}l\mathrm{and}{\mu }_{\mathrm{from}m}=\mathrm{one}/\left[\left(Q_n/{\nu }_n+Q_{\mathrm{at}}/{\nu }_{\mathrm{at}}+Q_g/{\nu }_g\right)\right]\left(\mathrm{four}\right)$$

as well as the unity of the mass of the mixture $$\mathrm{one}={\alpha }_n+{\alpha }_{\mathrm{at}}+{\alpha }_g\left(5\right)$$

when α _n = Q _n / Q _cm , α _in = Q _in / Q _cm , α _g = Q _g / Q _cm

The indices denoting n - oil, in - water, g - gas, refer to the density, viscosity and component mass and volume fractions of the mixture G _n , G _in , G _g and Q _n , Q _in , Q _g .

We believe that the density values ρ _n , ρ _c , ρ _g and viscosity μ _n , μ _c , μ _{g of the} components of the mixture are known for a particular borehole, are constant and amended for specific measurement conditions.

Expression (3) and (4) contains volumetric components of Q _n , Q _in , Q _g .

We have three equations with three unknown component components.

In the presence of known values of the density and kinematic and dynamic viscosity of the components of the mixture (assuming that they are const for the borehole under study, and corrections have been made for specific measurement conditions), as well as the measured value of Q _cm , then from three independent equations (3), (4) and (5) we obtain the mass and volume component components of the GHS - G _n , G _c , G _g and Q _n , Q _c , Q _g .

The essence of the proposed method consists in the fact that without spurious leaks through the rotor, the volumetric and mass flow rates of the mixture are determined as the sum of the component costs taking into account the density and viscosity of the mixture by calculation by known equations, and then the component composition of the mixture is determined.

The proposed method for evaluating the component composition of the flow rate from the well has the following advantages:

- simplification of the method of measuring component-wise volumetric and mass flow rate with a limited instrumentation composition of the measuring device, i.e. reduction of measuring and computational operations requiring simultaneity for a more reliable measurement of medium flow.

- when measuring the volumetric flow rate, the current error is maintained over the entire range,

- lack of leakage of an expense provides high accuracy,

- the mixture is not subjected to compression and expansion, passing through the measuring section when measuring volumetric and mass flow,

- improves the accuracy of the flow meter due to a decrease in the influence of viscosity, density,

- improves the accuracy and reliability of the flowmeter when measuring flows with high pressure levels and pressure pulsations in a wide range of flow rates of the measured medium.

Claims (1)

A method for measuring the component flow rate of a gas-liquid mixture, including measuring volumetric flow rate and transmitting data to a computer, characterized in that the rotor speed is maintained at zero pressure drop, the rotor torque, its rotation speed and viscosity are measured, the mixture density is determined by the amount of torque moment and equate it to one of two well-known equations relating the density, viscosity and component parts of a three-component mixture, the measured viscosity coefficient cm B is compared with the other of the two known equations calculator recovered from three independent equations of mass and volume Exploded components of the mixture.