RU2126143C1 - Ultrasonic flowmeter of components of multiphase medium - Google Patents

Abstract

FIELD: information and measurement systems in oil refining and oil producing industries. SUBSTANCE: measurement chamber of flowmeter has capability for uninterrupted passing of portion of flow between radiator and detector of acoustic signals to take measurements inside flow in pipe-line. Radiator and detector are placed on opposite walls of chamber at distance of 1.0-20.0 mm. Measurement chamber is connected to unit measuring parameters of pulses coupled to computer system which also receives information from unit measuring velocity positioned with displacement along movement of flow and including second measurement chamber with radiator and detector of acoustic pulses. EFFECT: high accuracy of determination of composition of multicomponent medium changing in time. 1 dwg

Description

 The invention relates to measuring equipment and can be used in information-measuring systems of oil refining, oil production, chemical and other industries.

 The classical designs of flowmeters for assessing the quantitative and qualitative composition of the oil and gas stream coming from production wells are based on measurements of the density of the stream and its speed, taking into account fluctuations of controlled physical parameters caused by the presence of inhomogeneities in the liquid phase in the form of, for example, gas bubbles.

 So, the ultrasonic flowmeter of multiphase media is known, the principle of which is based on the selection of the predominant frequency of the Doppler signal (Kremlevsky PP, Flowmeters and counters of quantity. - L .: Mashinostroenie, 1989). This is done by selecting and accumulating the most frequently repeated time intervals between the moments of crossing the Doppler frequency signals of the zero level. The selection and accumulation of the most frequently repeated measured time intervals is carried out using a memory unit. At the same time, each measured time interval is assigned its own memory cell.

 The disadvantages of this device, as well as others, considered during the patent search, are connected with the fact that the pulse emitter and the receiver of transmitted signals are located at a considerable distance from each other from the outside of the pipeline. Therefore, high errors in the measurement of parameters of pulses transmitted through a controlled medium are inevitable, leading to a distortion of information on the composition of the medium.

 The closest in technical essence to the proposed invention is an ultrasonic flow meter in accordance with the patent of the Russian Federation 2062995, class. G 01 F 1/66, 1996. It is equipped with a vertically mounted measuring chamber with inlet and outlet nozzles, a control unit and a density measuring unit and a second counting and recording device connected in series. In this case, the piezoelectric transducers are located on the upper and lower walls of the measuring chamber, the inputs of the control unit are connected respectively to the inputs of the flow measuring unit and the density measuring unit, and the output of the control unit is connected to the input of the switching device and the first input of the density measuring unit, to the second input of which the piezoelectric transducer is connected located on the bottom wall of the measuring chamber.

 The technical result of this solution is that the direct and inverse piezoelectric effect and the measurement of flow and density in one zone are used on the same transducers. And this allows us to exclude errors during device calibration and changes caused by fluctuations in the properties and parameters of the controlled medium along the flow.

 The disadvantages of the prototype device are related to the fact that it is a batch device that monitors the flow of a multiphase medium outside the pipeline and, accordingly, does not take into account the time-varying ratio of components in the flow. Hence the inaccuracy of the resulting information on the real phase relationships, which in some cases, for example, when analyzing the state of oil wells produced, can lead to inadequate decision making.

 Therefore, the task of the invention is to increase the accuracy of determining the composition of a multiphase multicomponent medium.

 The problem is solved by means of an ultrasonic flowmeter of components of a multiphase medium containing a measuring chamber in the pipeline, on the opposite sides of the chamber there is a pulse emitter and a receiver of pulses transmitted through the medium, connected to a block for measuring parameters of registered pulses and to an electronic computer system, and in which with the invention, for taking measurements inside the pipeline, the measuring chamber is configured to continuously transmit part of of current in the space between the emitter and the receiver located at a distance of 1–20 mm from each other, the parameter measuring unit additionally contains a counter of pulses that have not passed through the gaseous medium and is connected to an electronic computer system, which also receives information from the speed measuring unit located at displacement in the direction of flow and containing the second measuring chamber.

 The difference of the proposed device is that it contains a controlled volume in the form of a measuring chamber, which is placed directly in the stream of a multiphase multicomponent medium. In this case, the camera contains an emitter and a receiver of acoustic pulses located on opposite walls, the optimal distance between which is 1-20 mm. This parameter is established empirically. When the distance between the emitter and the receiver is less than 1 mm, it is difficult to fix the change in the parameters of transmitted pulses depending on changes in the composition of the stream, and at a distance of more than 20 mm the error in measuring the parameters of transmitted pulses increases.

 The proposed device assumes a different compared with the known approach to determining the composition of the controlled environment. In the process of measuring the transit time of acoustic pulses in the space between the emitter and the receiver directly in a controlled environment. Depending on changes in the composition of, for example, oil and gas flow, time periods vary accordingly. If a gas phase appears in this space, energy pulses are absorbed, and the signal disappears. In this case, the measuring system records the time of signal absence.

A diagram of an ultrasonic flow meter in accordance with the claimed invention is presented in the drawing. Here 1 is a pipeline with a multiphase multicomponent medium; 2 - pulse emitter; 3 - receiver of pulses transmitted through the medium; 4 - pulse generator; 5 - unit for measuring pulse parameters; 6 - electronic measuring system; 8 - pulse emitter of the second measuring chamber; 9 - receiver of transmitted pulses in the second measuring chamber; 7 and 10 - controlled volumes; 11 - flow rate measuring unit; 12 - processing unit of the amplitude of the pulses
The device operates as follows. The measuring chamber with the emitter 2 and the receiver 3 is placed inside the pipe 1 so that the measured medium passed through the controlled volume 7.

 Acoustic pulses passing through the monitored volume 7, get to the input of the pulse parameters measuring unit 5, where the time it takes for the acoustic pulses to pass the monitored volume (pulse duration) is recorded and its (time) is converted to the amplitudes of the measuring signals. The magnitude of the amplitude corresponds to the acoustic conductivity of the medium, which is currently in a controlled volume, which makes it possible to determine the composition of the controlled medium.

The gas fraction is estimated by the time of the absence of an acoustic signal in the controlled volume T = Σ _j t _i
D _g = T / T ₀
where T is the sampling time;
t _i is the residence time of the gas inclusion in a controlled volume.

где τ - время прохождения акустической волны от излучателя к приемнику (длительность импульса);
τ_н,τ_в - калибровочные значения длительности акустических импульсов соответственно в нефти и воде.The proportion of oil is estimated by the ratio

where τ is the transit time of the acoustic wave from the emitter to the receiver (pulse duration);
τ _n , τ _in - calibration values of the duration of acoustic pulses, respectively, in oil and water.

Для определения скорости среды по ходу движения потока устанавливают вторую измерительную камеру 10, образованную излучателем 8 и приемником 9. Измерительная камера 10 и соединенный с ней блок обработки амплитуды импульсов 12 образуют блок измерения скорости потока 11, который подключен к электронно-вычислительной системе 6. Скорость среды определяется корреляционным методом. При этом в блок обработки амплитуды импульсов 12 блока измерения скорости 11 поступают сигналы от двух измерительных камер 7 и 10, и получаются две реализации дискретных случайных взаимокорреляционных величин Х_i и Y_i. При этом корреляционная функция представлена следующим образом:

,
j = 0,1,2,...k
Находя max R_xy и соответствующие ему j, определяют время движения среды от первого контролируемого объема 7 ко второму объему 10. Используя известные величины: расстояние между контролируемыми объемами L и время движения среды τ_cp, определяют объемный расход
Q = kSL/τ_cp
где S - сечение трубопровода;
k - тарировочный коэффициент.Similarly, the proportion of water is determined

To determine the speed of the medium along the flow, a second measuring chamber 10 is formed, formed by the emitter 8 and the receiver 9. The measuring chamber 10 and the pulse amplitude processing unit 12 connected to it form a flow velocity measuring unit 11, which is connected to the electronic computer system 6. Speed environment is determined by the correlation method. At the same time, signals from two measuring chambers 7 and 10 are received in the pulse amplitude processing unit 12 of the speed measuring unit 11, and two realizations of discrete random cross-correlation values X _i and Y _i are obtained. In this case, the correlation function is presented as follows:

,
j = 0,1,2, ... k
Finding max R _xy and the corresponding j, determine the time of the medium from the first controlled volume 7 to the second volume 10. Using the known values: the distance between the controlled volumes L and the time of the medium τ _cp , determine the volumetric flow
Q = kSL / τ _cp
where S is the cross section of the pipeline;
k is the calibration factor.

 The volumetric flow rate of the components is determined based on the proportion of each component. The signals from the measuring units enter the electronic computing system 6, which gives the measurement result in the form of the ratio of all components of the medium.

 The authors made a prototype of the device, which implements the proposed technical solution NVGR-1. It was tested at the Pervomaiskoye field of the Krasnokamsk oil production site of CJSC Lukoil-Perm (well bush 4) in December 1997.

Based on the test results, the following conclusions are made:
- the selected technical solutions made it possible to reliably fix the parameters of the received signals and carry out their effective processing at all well operation modes;
- the numerical values of the flow parameters obtained during the measurements are close to measurements using standard measuring systems and the values obtained in laboratory tests.

Claims (1)

 An ultrasonic flowmeter of components of a multiphase medium in a pipeline containing a measuring chamber, on the opposite walls of which are located a pulse emitter and a receiver of pulses transmitted through the medium, connected to a block for measuring parameters of pulses transmitted through the medium, and an electronic computer system, characterized in that the measurement the camera is configured to continuously transmit part of the stream in the space between the emitter and the receiver, located at a distance of 1 - 20 mm from each other, and in the direction of flow, a flow velocity measuring unit is connected to the electronic computer system, comprising a second measuring chamber.