RU2789623C1 - Multiphase flow meter - Google Patents

Abstract

FIELD: information-measuring systems.

SUBSTANCE: invention relates to the field of measuring the parameters of the flow of a multi-phase fluid and can be used in information-measuring systems of the oil-producing, oil-refining industries. The multiphase flow meter is a Venturi tube with temperature sensors installed at the confuser inlet and diffuser outlet and pressure sensors installed in the confuser and neck, in the neck wall of which, in the section plane perpendicular to the direction of the multiphase fluid flow, two X-ray transparent windows are made opposite each other, in one of which a radiation source is installed, and in the other - a radiation detector, while in the neck wall in the same sectional plane an additional X-ray transparent window is made, located at an angle of 90° to the axis between the radiation source and the radiation detector, in which an additional radiation detector is installed , and blocks for measuring the proportion of water and the proportion of methanol, including a microwave emitter and a microwave radiation detector, are installed in series at the confuser inlet.

EFFECT: high accuracy of measuring the parameters of a multi-phase fluid flow in various pipeline systems in real time without complicating the design of the device.

1 cl, 2 dwg

Description

The invention relates to the field of measuring the parameters of the flow of a multi-phase fluid and can be used in information-measuring systems of the oil-producing, oil-refining industries.

Currently, there is a global trend in the oil and gas industry towards digitalization and optimization of control processes for various parameters. One of these processes is the control and accounting of the flow rates of hydrocarbons produced on the surface. The traditional way to account for a well fluid is separation followed by measuring the flow rates of each phase separately. However, this method is significantly outdated, does not meet modern requirements and needs to be replaced.

Over the past decades, several flow meters have been developed that belong to the category of multiphase (MPF) and do not require pre-separation of the well fluid. Such MFRs make it possible to measure the quantitative characteristics of a multiphase flow directly in linear conditions and to recalculate them to standard conditions in a wide range of flow regimes. Most often, MPFMs are used when conducting hydrodynamic testing of wells, as well as for accounting for production during the commercial operation of wells. The compact size of the MFR compared to separator units allows the creation of mobile measuring systems to effectively meet the needs of customers.

Despite the significant advantages of the MFR, these systems also have characteristic disadvantages:

- low accuracy of determination of the liquid fraction at high values of the gas condensate fraction (GVF);

- High sensitivity to changes in the composition of the fluid, requiring a shutdown of the process and reconfiguration of the MFR;

- the inability to determine the flow rate;

- high cost of ensuring radiation safety, transportation and operation of the source of gamma radiation.

Known multiphase flow meter (see patent RU No. 2632249, IPC G01F1 / 58, published 03.10.2017), containing:

a channel containing a multiphase fluid flow;

a radioisotope source and a radioisotope sensor configured to detect nuclear energy emitted by the radioisotope source through the channel and flow of the multiphase fluid; and an electronic instrument configured to:

determining the flow regime and gas content of the multiphase fluid stream based on the nuclear energy detected by the sensor compared to the expected radioisotope sensor noise under steady flow conditions;

determining the stationarity of the multiphase fluid flow based on the detected flow regime;

selecting a variable from the plurality of variables based on the detected gas content and the detected stationarity; and modeling the multiphase fluid flow by adjusting the selected variable.

The main disadvantage of the known flow meter is the lack of accuracy in determining the parameters, due to the fact that for different conditions of the fluid flow and its composition, the correction factors and are determined on the basis of mathematical modeling, the results of which in different cases have different errors.

A multiphase flow meter adopted as the closest analogue is known (see patent RU No. 2663418, IPC G01F 1/74, published on 08/06/2018), containing a means of radiation, an X-ray transparent section of the pipeline for studying a multi-phase liquid, after which an anti-scattering X-ray mask is located to reduce the effect of radiation on the image, a matrix X-ray detector as a detection means, an analysis tool configured to determine the flow rate of one or more liquid phases and / or its composition, while an X-ray filter is installed in front of the matrix X-ray detector, which is made of two types of filter materials, having different absorption coefficients and arranged in a checkerboard pattern so that each filter cell is above its own pixel of the matrix detector, while after the X-ray transparent area, parallel to the matrix X-ray detector, a spectrometer is installed, which is used to measure the intensity X-ray radiation, taking into account its distribution over photon energies.

The known device makes it possible to use an X-ray tube with a broadband radiation spectrum as a means of radiation and improves the calibration accuracy, but also does not provide sufficient measurement accuracy due to radiation power losses when passing through the X-ray filter.

The objective of the proposed technical solution is to improve the accuracy of measurements for fluids with different flow parameters and phase composition.

The technical results of the invention lie in the high accuracy of measuring the parameters of a multi-phase flow without complicating the design of the device.

The technical results are achieved by the fact that the multiphase flowmeter is a Venturi tube with temperature sensors installed at the confuser inlet and diffuser outlet and pressure sensors installed in the confuser and neck, in the neck wall of which, in the sectional plane perpendicular to the direction of flow of the multiphase fluid, opposite to each other each other, two radiolucent windows are made, in one of which a radiation source is installed, and in the other a radiation detector, while in the neck wall in the same sectional plane an additional radiolucent window is made, located at an angle of 90 ° to the axis between the radiation source and the radiation detector, in in which an additional radiation detector is installed, and blocks for measuring the proportion of water and the proportion of methanol, including a microwave emitter and a microwave radiation detector, are successively installed at the confuser inlet.

The claimed invention is illustrated by drawings, where in Fig. 1 shows a schematic diagram of a multiphase flow meter, FIG. 2 is a section A-A according to FIG. 1.

The multiphase flow meter contains a Venturi tube 1 with X-ray transparent windows 2, 3 and 4, a radiation source 5, radiation detectors 6 and 7, pressure sensors 8 and 9, temperature sensors 10 and 11, a block 12 for measuring the proportion of water, a block 13 for measuring the proportion of methanol.

The procedure for working with the device is as follows:

1. The device is built in series in a hydrocarbon transportation line.

2. Prior to inclusion in the main operation, the device is calibrated according to the following data: radiation absorption for a single-phase medium; calibration coefficients of the Venturi tube; clarifying absorption coefficients of different mixtures obtained experimentally; calibration coefficients of microwave radiation detectors.

3. The device is included in the main work, the calculation results are recorded on a computer to collect and store information. Upon request, all data is transmitted to a remote server. Additional and periodic calibration of the device is carried out in accordance with the requirements of the device maintenance regulations.

During operation of the device, various physical parameters are measured, the processing of which makes it possible to determine with high accuracy the phase quantitative composition of the fluid passing through it.

Conditionally measured parameters can be divided into several groups.

The first group is related to measurements of pressure, pressure drop and temperature (P_line, ΔP, T_line) along the Venturi tube, on the basis of which the primary calculation of fluid density and flow rate is performed.

In the neck of the Venturi tube, an increase in dynamic pressure occurs due to an increase in the velocity of the multiphase fluid and a decrease in static pressure. This phenomenon is described by Bernoulli's law:

,

,

ρ - density;

V - speed;

P - static pressure.

The static pressure difference between the pipeline and the venturi neck is measured by pressure sensors 8 and 9 (representing together a differential pressure gauge). To calculate the flow rate of the analyzed medium, the Venturi effect equation is used:

,

,

Q is the volumetric flow rate of the medium;

S1 and S2 are the cross-sectional areas of the pipeline and the neck of the Venturi pipe;

ρ is the density of the medium (calculated based on temperature data from temperature sensors 10 and 11);

P1 and P2 - static pressures at the inlet and in the neck of the Venturi pipe;

C - empirical loss factor (reflects the discrepancy between the real effect and the practical one).

The coefficients C are found experimentally for different flow rates, mixture compositions, and velocities on the pouring stand.

The second group of parameters is associated with the detection by detectors 6 and 7 of radiation passing from source 5 (for example, gamma rays from Ba-133 or from an X-ray source) through a multiphase medium in the range from 20 to 100 keV. In this case, the function of the number of particles N(E,t) is recorded, which depends on energy and time for each of the two detectors 6 and 7. This makes it possible to determine the component composition of the fluid and the molar composition of the components contained in it.

For this:

1. In the neck of the Venturi tube, windows are made of X-ray transparent material that do not violate the geometry of the Venturi tube.

2. On one side of the tube, a radiation source 5 is installed, which shines through the window a multi-phase fluid flow in a plane perpendicular to the direction of its movement.

3. On both sides in the same plane as the incoming beam collimator, opposite the other windows, scintillation detectors 6 and 7 with photomultipliers are installed.

During the passage of gamma rays through the mixture, one part of them is scattered at an arbitrary angle with a small loss of energy (Compton effect), the second part is absorbed, causing ionization of the atoms of the mixture (photoelectric effect), and the third part passes through the flow without experiencing any absorbing or scattering effects.

Detectors 6 and 7 detect scattered and transmitted gamma quanta. The density of the medium is determined by the number of detected high-energy gamma rays (above 50 keV).

Theoretically, with a single-phase medium, knowing its average density, it is possible to calculate the flow rate. But, since the medium in this case is represented by three phases: water, condensate and gas, it is also necessary to find out the phase composition, that is, the ratio of water to hydrocarbons (because the ratio of gas to liquid is calculated by density).

To do this, low-energy photons (below 50 keV) are detected, which are more sensitive to gaseous media, which makes it possible to more accurately differentiate the composition of a multiphase flow.

The presence of an additional detector 7, located at an angle of 90° to the axis between the radiation source 5 and the detector 6, which detects scattered radiation, makes it possible to correct the data obtained by the detector 6, which increases the accuracy of determining the components of the fluid phase composition, especially in cases of high GOR (≥ 80 %).

The third group of parameters are the results obtained from blocks 12, 13 for measuring the proportion of water and methanol based on a microwave emitter.

Since the water component of a multiphase fluid always contains dissolved methanol (which is, in fact, part of the gas component), measurements using blocks 12, 13 can further improve the accuracy of determining the actual mass volume of the multiphase fluid components.

The proposed technical solution provides high accuracy in determining the parameters of a multi-phase fluid flow in various pipeline systems in real time.

Claims (1)

A multiphase flow meter, which is a Venturi tube with temperature sensors installed at the confuser inlet and diffuser outlet and pressure sensors installed in the confuser and neck, in the neck wall of which, in the section plane perpendicular to the direction of flow of the multiphase fluid, two X-ray transparent windows are made opposite each other , in one of which a radiation source is installed, and in the other - a radiation detector, characterized in that an additional X-ray transparent window is made in the neck wall in the same section plane, located at an angle of 90 ° to the axis between the radiation source and the radiation detector, in which an additional radiation detector, and blocks for measuring the proportion of water and the proportion of methanol, including a microwave emitter and a microwave radiation detector, are installed in series at the confuser inlet.

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