RU2014568C1 - Method of determining the phase rate of the multiphase liquid flow and device for its realization - Google Patents

Abstract

FIELD: petroleum industry. SUBSTANCE: heat pulse is actuated depending on the power type preliminary determined by the conducting properties and his amplitude-time characteristics are registered by not less than two temperature pick-ups separated from each other. The dielectric permittivity is measured between these pick-ups while the heat pulse is passing. The ideal value of the heat capacity per unit volume of the multiphase flow is determined taking into account the energy dissipation of the original heat flow, the rate of each phase of the multiphase flow is also determined. The device also has a pulsed light source located inside heat-insulating tube 1 and temperature pick-ups 8,9,10 located below and above the light source. Dielectric permittivity transducer 11 and pressure pick-up 3 are placed between the temperature pick-ups. The heat source is made in the form of two independent sources connected depending on the liquid type by the conducting properties. The heat source for heating the dielectric liquid is made in the shape of spiral 4,5, whose temperature is set below that of spontaneous ignition of hydrocarbon gases. The heat source for heating the conducting liquid is made in the form of central supply electrode 6 and cylindrical electrode 7. EFFECT: enhanced accuracy of determining the quantitative values of phases with the simultaneous enhanced operation safety. 3 cl, 2 dwg

Description

 The invention relates to the oil industry and can be used to determine the total flow rate of a multiphase liquid, the flow rate of its individual phases (oil, water, gas), the gas factor of oil, the salinity of the aqueous phase, temperature and pressure of the multiphase flow in field pipelines.

 A known method of measuring the flow rate of phases of a multiphase flow in wells, based on measuring the total flow rate of a multiphase flow, fluid density by gamma-ray transmission and its dielectric constant, and a device for its implementation, consisting of a ground recording device and a downhole tool in which a turbine fluid flow transducer is installed , a Geiger counter, a gamma radiation source for measuring liquid density and a permittivity sensor.

 The disadvantages of this technical solution are the large errors of the gamma-ray transmission method in low-density media, such as gas-liquid mixtures, and the low accuracy of turbine transducers when measuring the flow rate of a multiphase liquid containing free gas, organic and inorganic salts. In addition, the use of sources of radiation is dangerous to the life of staff.

 A known method of measuring the flow rate of phases of a multiphase flow, based on the start of a heat pulse, recording with its temperature sensor its amplitude-time characteristics and measuring the electrical conductivity of the liquid, and a device for implementing this method, consisting of a downhole part, including a pulsed heat source and heat-sensitive elements located on opposite ends of the pipe made of heat-insulating material, heating electrodes brought into the flow of the test fluid and shunted by the resistance a control panel, which allows to measure the total flow rate, electrical conductivity and heat capacity of the fluid in the well.

 The main disadvantage of the known technical solution is the low accuracy of the measurement in connection with the registration of the heat pulse by only one temperature sensor, which is associated with errors in determining the heat capacity of the liquid. The use of heating electrodes brought into the flow of the test fluid and shunted by open resistance for pulsed heating of the electrically conductive and dielectric fluids leads to burnout of the shunt resistance due to electrolysis in the electrically conductive fluid.

 The aim of the invention is to improve the accuracy of measuring the total flow rate of an unsteady multiphase flow and the flow rate of its individual phases while improving operational safety.

 This is achieved by preliminarily determining the type of liquid being measured, generating a thermal impulse depending on the type of liquid, measuring the amplitude-time characteristic of the thermal impulse in at least two points at a fixed distance from each other, simultaneously determining the dielectric constant of the liquid and calculating the true value of the volumetric heat capacity of the multiphase flow taking into account the dissipation of the heat pulse and the flow rate of each phase of the multiphase flow. In addition, the device containing a pulse heat source, a temperature sensor and a control unit located in the measuring section of the pipeline is equipped with at least two temperature sensors, a pressure sensor and a dielectric constant meter, and the pulse heat source is made in the form of two independent sources for electrically conductive heating and dielectric fluid, with one temperature sensor installed in front of the pulsed heat source, and the rest behind it at a fixed distance from each other, yes snips pressure and permittivity are installed therebetween and are connected to the inputs of the control unit, the outputs of which are connected to each of the independent heat sources, while an independent source of heat for the dielectric liquid is in the form of a spiral.

 In FIG. 1 shows a structural diagram of a device; figure 2 - functional diagram of the device.

 The device consists of a block of primary converters (BPP) (Fig. 1) and a block for receiving and transmitting information (BPPI) (Fig. 2), interconnected with a central computer by communication channels.

 BPP consists of a pipe 1 with flanges at opposite ends, with which the pipe is vertically built into the pipeline through which the multiphase fluid flows. Inside the pipe 1, a pipe 2 made of heat-insulating material is coaxially installed, the live section of which is several times smaller than the living section of the pipe 1. A pressure sensor 3 is installed in the annulus. Two types of heating elements 4 and 5 of a pulsed heat source are installed in the pipe’s inner cavity 2. One of the heating elements consists of a central current-conducting electrode (anode (6 and a cylindrical cathode 7, which are simultaneously measuring electrodes of the electrical conductivity sensor. The other heating element is made in the form of a spiral from an open heating wire, combined along the length with the electrodes of the first heating element. Each heating element the element has independent power sources.In the internal cavity of the pipe 2, temperature sensors 8, 9 and 10 are installed. The sensor 8 is installed before impu heating elements, two or more sensors 9, 10 - behind the pulse heating elements .. Between the two upper temperature sensors on the outer surface of the heat-insulating pipe 2 is wound from an insulated wire dielectric constant sensor 11.

 BPPI consists of current meters (IT) 12, a block of thyristor switches (BTK) 13, a heating transformer (NT) 14, a block of preliminary amplifiers and shapers (BPU and F) 15, a block of analog-to-digital converters and switches (ADC and K) 16 , control circuits of switches and temporary converters (QMS and VP) 17, power supply unit (PSU) 18 and central processing unit (CPM) 19.

 The device operates in the following sequence.

 The central computer transmits a command to the CPM 19 about the beginning of the measurement cycle. The CPM through BTK, QMS and VP, BPU and F includes sensors of electrical conductivity, dielectric conductivity, pressure and temperature. The electrical conductivity of a multiphase liquid is determined based on the measurement of the discharge time of the storage capacitor through the BTK, electrodes 6, 7 and the liquid. The dielectric constant is determined by measuring the electric capacitance of the medium in the annulus between the coil of the sensor 11 and the body of the pipe 1. The temperature and pressure are measured by sensors 8, 9, 10 and 3. Information about the physical parameters of the multiphase liquid is transmitted to the central computer 19, which according to a special program calculates the electrical characteristics of a multiphase fluid. When an electrically conductive liquid CPM flows through a BPP through a QMS and VP, BTK, IT, it includes a heating element with electrodes 4 and 5, which provides pulsed heating of the liquid as a result of the passage of electric current through the liquid. When a dielectric fluid flows through a BPP, the pulse is heated by a heating element in the form of a spiral, and the spiral current is set so that the heating temperature of the spiral is lower than the self-ignition temperature of associated hydrocarbon gases in the presence of air in the gas phase, for example, during compressor operation of wells.

 Simultaneously with the start of the pulsed heat source, pressure and temperature sensors are activated. When approaching the near temperature sensor 8 of the heat pulse, the dielectric constant sensor 11 is turned on at a certain recording frequency. The dielectric constant measurement continues until the same heat pulse is transferred to the far temperature sensor 10. After the trailing edge of the heat pulse passes through the farthest temperature sensor 10, the central computer gives the command to the CPM 19 to stop the given measurement cycle. The device returns to its initial state and is ready for the next measurement.

 The method is carried out by the sequence of the following technological operations.

 The type of liquid is determined by the electrically conductive properties, for which, upon a command from the central computer, a unit for measuring the electrical characteristics (conductivity and permittivity) of the multiphase flow is launched through the CPM 19.

, (1) где Т - средняя температура теплового импульса, С^о;
Р - мощность источника, Вт;
С_v - объемная теплоемкость, Дж (м³˙град);
Q - общий расход МФП, м³/с.Fluid conductivity σ is determined by measuring the discharge time τ of a calibrated capacitance C _τ through electrodes and liquid. The dielectric constant ε is determined from the information received from the capacitive sensor 11. Information from the sensors 11 and 6, 7 is transmitted to the central computer, where the parameters σ and ε are determined by the algorithms described below. According to their values, the type of liquid is established - conductive or dielectric. Depending on the type of fluid, an appropriate source for generating a heat pulse is included. In a dielectric fluid, a heat pulse is generated using a spiral electric heater, and in an electrically conductive fluid, by passing current through a fluid (discharge heater). Power sources are selected in such a way that in the operating range of measurement of the multiphase flow heat pulse amplitude costs were not less than 0.5-1 ^C. For optimization of the selection power source is used the ratio
T =

, (1) where T is the average temperature of the heat pulse, C ^o ;
P is the power of the source, W;
With _v - volumetric heat capacity, J (m ³ д deg);
Q - total flow rate of the MFP, m ³ / s.

 It was found that the power of the spiral heater should be 200-400 W, and the power of the discharge heater should be in the range of 1.5-5 kW.

The duration of the thermal pulse (heater operating time) Δt _n must exceed the inertia time of the thermal sensors and be 2-3 times less than the transit time of the thermal pulse from the source to the nearest temperature sensor t _m1 , i.e. pulse duration is selected from the condition
t ₃ <t _n <t _m1 .

 After determining the type of liquid and supplying a thermal impulse, BPPI with a given discreteness in time conduct a survey of temperature sensors 8, 9, 10 and transmit information to a central computer.

=

T_i;

=

;
i=1, 2, ..., m (2)
За момент прихода тепловой метки к температурному датчику принимается время t_m, для которого выполняется условие
1/3(T_m+T_m+1+T_m+2)>(

+3σ_m) (3)
С момента времени t_m вычисления средней температуры и дисперсии прекращают и начинают интегрирование кривой изменения температуры
J=

T(t)dt (4)
Момент времени t_к, когда прекращают опрос температурного датчика, определяется из аналогичного условия, приведенного выше
1/3(T_к-2+T_к+1+T_к)≅(

+3σm) (5)
Операции (2)-(5) проводятся с данными обоих температурных датчиков. В момент времени t_m1 (время прихода тепловой метки к ближнему от источника датчику 9) БППИ начинает опрос и передачу данных емкостного датчика 11 в ЭВМ. Здесь данные емкостного канала усредняются в интервале времени прохождения тепловой метки от ближнего датчика 9 к дальнему датчику 10.The computer implements the following algorithm for processing temperature sensor data. For each current time t _m , the average temperature T _m and the variance σ _m for each of the sensors are calculated by the formulas

=

T _i ;

=

;
i = 1, 2, ..., m (2)
At the time of arrival of the heat label to the temperature sensor, the time t _{m is} taken, for which the condition
1/3 (T _m + T _{m + 1} + T _{m + 2} )> (

+ 3σ _m ) (3)
From the time t _{m, the} calculation of the average temperature and dispersion is stopped and the integration of the temperature curve begins
J =

T (t) dt (4)
_To time t, when the stop polling the temperature sensor is determined from the similar conditions above
1/3 (T _c-2 + T _{c + 1} + T _c ) ≅ (

+ 3σm) (5)
Operations (2) - (5) are carried out with the data of both temperature sensors. At time t _m1 (time of arrival of the heat mark to the sensor 9 closest to the source), the BPPI begins to poll and transmit data from the capacitive sensor 11 to the computer. Here, the capacitive channel data are averaged over the time interval of the passage of the heat mark from the near sensor 9 to the far sensor 10.

c_i, (6)
где n - число спросов емкостного датчика в интервале времени Δ t.The average value of the capacitance C in the indicated time interval (Δt = t _m2 -t _m1 ) is determined by the formula
C =

c _i , (6)
where n is the number of capacitive sensor demand in the time interval Δ t.

By the time t _k2 , when the interrogation of the distant temperature sensor 10 stops, all the necessary information is accumulated in the computer to calculate the total flow rate and the flow rate of the phases of the other phase flow.

 In addition to the above operations with primary computer information, using a number of calibration dependences obtained at the stage of the metrological setup of the meter, it recalculates the output signals of the sensors into the corresponding physical parameters (dielectric constant, conductivity, total consumption, etc.).

The values of σ and ε calculated from the calibration dependences ε = f (c _x ); σ = f (τ), are used to determine the type of fluid by electrical properties.

The power of the discharge source W is found from the calibration dependence W (τ). The power of the spiral heater in a non-conductive liquid is constant and is calculated by the well-known formula
W = V ² / R, (7) where V is the voltage supplied to the heater,
R is the resistance of the heater.

The energy transferred to the thermal pulse is calculated by the formula
E = W˙Δ t _n , (8)
where Δ t _n is the pulse duration.

 The transfer time of the heat label from the source to the temperature sensor is determined by the total flow rate Q of the MFP (multiphase flow).

(Q₁+Q₂+Q_Δ), (9)
Малая дисперсия Q₁, Q₂, Q_Δ от их среднего значения служит критерием надежности расчета общего расхода Q.According to the values found above, t _m1 , t _m2 , Δ t determine the costs Q ₁ (1 / t _m1 ) from the calibration dependencies; Q ₂ (1 / t _m2 ); Q _Δ (1 / Δ t) and calculate the total flow rate Q MFP according to the formula
Q =

(Q ₁ + Q ₂ + Q _Δ ), (9)
The small dispersion Q ₁ , Q ₂ , Q _Δ from their average value serves as a criterion for the reliability of the calculation of the total flow Q.

· exp(-αL₁) , (10) где α - коэффициент, учитывающий диссипацию энергии теплового импульса Е при прохождении от источника тепла до температурных датчиков, вычисляется по формуле
α=ln

/(L₂-L₁) , (11) где L₁, L₂ - расстояния от источников до ближайшего 9 и дальнего 10 датчиков соответственно.The volumetric heat capacity C _{v of a} multiphase flow is calculated by the formula
C _v =

· Exp (-αL ₁ ), (10) where α is the coefficient that takes into account the dissipation of the energy of the thermal pulse E when passing from the heat source to the temperature sensors, is calculated by the formula
α = ln

/ (L ₂ -L ₁ ), (11) where L ₁ , L ₂ are the distances from the sources to the nearest 9 and far 10 sensors, respectively.

где C_vi, α_i (i=1,2,3) - объемные теплоемкости воды, нефти и газа и объемные содержания фаз в потоке соответственно;
ε, α - скалярные векторы диэлектрической проницаемости компонент их объемных содержаний;
σ_в,α_в - удельная проводимость воды и ее содержание.The calculation of the volumetric content of phases (oil, gas and water) is carried out based on the solution of the following system of equations

where C _vi , α _i (i = 1,2,3) are volumetric heat capacities of water, oil and gas and volumetric phase contents in the stream, respectively;
ε, α are scalar vectors of dielectric constant of the components of their volume contents;
σ _in , α _in - specific conductivity of water and its content.

 The first equation of the system follows from the law of conservation of energy.

Satisfactory results with the meter layout were obtained using the dependences Ф _{1 (} ε, α), Ф ₂ (σ _в , α _в ), based on the theoretical constructions of Bruggeman (for specific conductivity) and Odelevsky (for dielectric constant).

(1-α_в)^3/2 (13)
Σ

·α_i=0 (14)
С учетом соотношений (13) и (14) система (12) сводится к линейной системе уравнений. Алгоритм решений систем (12) базируется на вычислительных схемах, устойчивых к погрешностям измерений, основанных на методах решения некорректных обратных задач.

(1-α _in ) ^3/2 (13)
Σ

Α _i = 0 (14)
Taking into account relations (13) and (14), system (12) is reduced to a linear system of equations. The algorithm for solving systems (12) is based on computational schemes that are resistant to measurement errors, based on methods for solving incorrect inverse problems.

(16) газовый фактор Г
Г=

. (17)
Все рассчитанные параметры МФП выводят на печать или магнитный носитель и измерительно-вычислительный комплекс готов к проведению нового цикла измерений.Calculate the phase flow rate Q _i (water, oil and gas)
Q _i = Q˙α _i (15) where i = 1,2,3
water cut η:
η =

(16) gas factor G
R =

. (17)
All the calculated parameters of the MFP are printed or magnetic media and the measuring and computing complex is ready for a new measurement cycle.

Claims (3)

 1. A method for determining the phase flow rate of a multiphase liquid flow, including generating a heat pulse, recording its amplitude-time characteristics and processing the results, characterized in that the type of liquid being measured is preliminarily determined by its electrical conductivity, the formation of a thermal pulse is carried out depending on the type of liquid, measurement amplitude-time characteristics produce at least two points remote from one another at a fixed distance, simultaneously determine ielektricheskuyu permeability measured fluid, and the processing of the results calculated true value of the volume heat capacity of the multiphase flow with heat dissipation and energy consumption pulse of each phase of the multiphase flow.  2. A device for determining the flow rate of phases of a multiphase liquid flow, comprising a pulse heat source and a temperature sensor located in the measuring section of the pipeline, as well as a control unit, characterized in that it is equipped with at least two temperature sensors, a pressure sensor and a dielectric constant meter, and a pulsed heat source is made in the form of two independent sources for heating an electrically conductive and dielectric fluid, with one temperature sensor installed in front of the pulsed a heat source, and the rest of them at a fixed distance from each other, and a pressure sensor measuring permittivity established therebetween, and their outputs are connected to inputs of the control unit, the outputs of which are connected to each of the independent heat sources.  3. The device according to claim 2, characterized in that the independent heat source for heating the dielectric fluid is made in the form of a spiral.

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