RU2530460C1 - Multiphase liquid analyser - Google Patents

Abstract

FIELD: measuring instrumentation.

SUBSTANCE: multiphase liquid analyser includes pulse source of fast neutrons and electromagnetic emission source, gamma spectrometer, gamma ray detector and scintillator diametrical the electromagnetic emission source on the opposite side of pipeline; pulse source of fast neutrons serves as pulse source of electromagnetic emission as well and additionally contains monitoring detector of fast neutrons and monitoring detector of electromagnetic emission; gamma spectrometer contains additional gamma ray collimator and is positioned beside the pulse source of fast neutrons and electromagnetic emission; gamma ray detector is positioned at the same side of pipeline with the pulse source of fast neutrons and electromagnetic emission at a given distance from the pulse source of fast neutrons and electromagnetic emission downstream by the multiphase liquid flow; fast neutron detector is diametrical to the pulse source of fast neutrons and electromagnetic emission at the opposite side of pipeline; thermal and epithermal neutron detector is positioned at a distance equal to fast neutron moderation length in the multiphase liquid, to the pulse source of fast neutrons and electromagnetic emission; gamma spectrometer, monitoring detector of electromagnetic emission and scintillator can measure electromagnetic pulse emission spectrum.

EFFECT: enhanced accuracy of fraction composition and flow measurement in multiphase liquid.

1 dwg

Description

The invention relates to a device for measuring the volume and flow rate of fluids, and more particularly, to a device for measuring the volume and flow rate (flow rate) of multiphase fluids, for example liquid hydrocarbon, water and gas flowing in a single pipe, for example, from a well to a separator, or mixtures of water and steam in the cooling system of a nuclear power plant and can be used to control flows with a variable flow rate, in particular, when monitoring the development status of oil and gas fields by measuring the productivity of each kvazhiny in a group or in nuclear power plants cooling control systems.

Monitoring the parameters and composition of the medium pumped through the pipeline at oil and gas fields is necessary for the proper operation of the well and the regime of oil production. It allows you to establish the increase in the flow of undesirable fractions, such as water or gas, and take timely measures to improve the situation.

Monitoring the parameters of the cooling system of nuclear power plants is important primarily to ensure its safe operation.

The measurement of multiphase flow parameters in oil wells and pipelines, including various flow regimes, is a serious problem in the oil industry. When oil is extracted through a pipeline leading from a well, water of various salinity and associated gas are pumped along with the oil. In addition to water, the oil and gas component, sand and solid hydrocarbons may also be present. Multiphase measurements should be carried out with the volume of the gas fraction in the range of 0-99% and with water cut in the range of 0-90%. The relative error in measuring the flow rates of liquid and gas flows should not exceed 5-10%, and the absolute error in measuring water cut should be within 2%. Measurement accuracy requirements increase when measuring multiple combined flows.

To accurately measure the flow of various phases of an oil / water / gas mixture, a multiphase flow meter is required that reliably operates under various flow conditions, including both streams with a high water content and streams with a high oil content in a wide range of water salinity and oil viscosity.

There are multiphase flow meters and control methods based on measuring the attenuation of the x-ray or gamma radiation transmitted in the plane of the section of the pipeline at several values of its energy. The flow regime, as well as the mass ratio of gas, water and oil in the pipeline, is determined by the ratio of attenuation at selected energies in various directions in the plane of the pipeline section. The choice of the radiation source is determined not only by the behavior of the linear attenuation coefficient of radiation energy for various fractions, but also by the size and thickness of the pipeline walls. To determine the fractional composition, the source spectrum should lie in the region of ≈10-100 keV. In order to remove the restrictions associated with the pipeline, a source with a more stringent spectrum of radiation is selected or a special branch from the main pipeline is used, called a Ventura tube with walls more transparent for low-energy X-rays.

The known "Method and system for determining the content of components in a multiphase fluid" [RF Patent No. 2466383, IPC: G01N 23/12 2012. Analog], the essence of which is that the method for determining the content of components in a multiphase fluid includes the following steps: creating an X-ray x-ray apparatus at single-energy or dual-energy levels, after which the said x-rays pass through a multiphase fluid, data at each energy level are detected by a detector subsystem, which consists of one or two detectors, and the mass percentage of the components in the multiphase fluid is calculated by the control and data processing subsystem based on the detected data.

The main disadvantages of the devices used to determine the characteristics of multiphase flows and based on the use of x-ray or gamma radiation are:

- the inability to obtain full coverage of the cross section of the pipe and the increase in measurement error with increasing pipe cross-sectional area due to the unilateral location of the source with respect to the flow;

- the need for an additional measuring device, for example a venturi, and the need in this case to take into account the annular distribution of the flux density;

- the influence on the measurement accuracy of mathematical models used to describe the spatial distribution of the density of the flow of a multiphase mixture;

- the need to use special fluoroscopic tubes, or the need to ensure safety measures when using radioisotope gamma sources;

- the dependence of the accuracy of determining the volumetric composition of the fractions on the spatial distribution of phases, the operating mode of the device, the salinity of the water and the specific density of the fractions, the presence of other impurities;

- the possibility of overloading the counting path with a high concentration of the gas fraction;

- the need for a priori knowledge of the actual values of the attenuation of x-ray or gamma radiation separately for each of the components of the mixture;

- the impossibility of measuring the content of impurities, such as sulfur-containing.

Multiphase flow meters and control methods using neutron radiation exist. These methods are based primarily on the possibility of determining the chemical composition of the medium from nuclear reactions that occur with the participation of neutrons and are accompanied by radiation of gamma quanta of a certain energy. So, for example, when water is irradiated with fast neutrons, oxygen is activated with a half-life T _1/2 = 7.2 s and gamma-ray emission with an energy of 6.1 MeV (68.8%) and 7.1 MeV (4.7% ) Inelastic scattering of fast neutrons by carbon, which is part of hydrocarbons, leads to the emission of instant gamma quanta with an energy of 4.43 MeV. The presence of sulfur and other elements can also be determined by the energy of gamma rays emitted as a result of inelastic scattering of fast neutrons.

Fast neutrons in a hydrogen-containing medium slow down rapidly. The resulting thermal neutrons experience hydrogen capture on hydrogen, which is accompanied by the emission of gamma rays with an energy of 2.23 MeV. In the presence of dissolved salt in water, thermal neutrons will also be effectively absorbed by the nuclei of chlorine atoms, as a result of which their lifetime in such an environment will depend on their number. The resulting chlor-36 isotope emits on average about 3 gamma quanta with a total energy of about 8 MeV. Due to the presence of chlorine in highly saline water, the gamma-ray spectrum is enriched with high-energy components.

Epithermal and thermal neutrons carry information about the composition of the medium not only from the gamma radiation of radiation capture. Their number, spatial distribution and lifetime in the medium depends on the mass, composition and spatial distribution of the density of the fractions that make up the liquid. The epithermal neutron flux, in contrast to the thermal neutron flux, is practically independent of the content in the environment of elements with a large capture cross section of thermal neutrons, including chlorine, and is determined mainly by the slowing properties of the medium - hydrogen content.

To measure the characteristics of multiphase fluxes, it is important that sources of fast neutrons based on portable neutron generators simultaneously emit x-rays, which are considered spurious and are caused by the electron current in the neutron tube. The spectrum of x-ray radiation coming out of the neutron generator is inhibitory and is determined by the accelerating voltage on the neutron tube, which usually exceeds 100 kV.

The known method: "Measurement of the characteristics of the inflow into the well using a neutron logging tool" [US Patent No. 7755032, IPC: G01V 5/10, 2010. Analog], which includes the "injection" of neutrons into the fluid flowing into the well table, registration gamma rays from the decay of nitrogen-16 in the borehole fluid stream using the first gamma detector, in-place measurement of water velocity from a measurement of gamma-ray decline, estimation of flow characteristics for one or more intervals in the well from data that include in-place velocity l the flow of water.

The disadvantage of the analogue is the inability to use the method for measuring the mass flow rate, phase composition and impurities of a multiphase liquid due to the fact that the method does not provide measurements of the density of the flowing liquid and gamma quanta of inelastic scattering and radiation capture.

A device for the "Analysis of liquids" [UK Patent No. 2182143, IPC: G01N 23/222, 1987. Prototype], comprising a gamma ray source and a diametrically arranged scintillator, a fast neutron source and a diametrically located gamma spectrometer, a pulsed source of very fast neutrons and a detector a gamma of rays, positioned as necessary for measuring fluid velocity.

The disadvantage of the prototype is the low accuracy and reliability of the measurements due to the fact that the measurement of the density of the liquid is carried out only to attenuate gamma (electromagnetic) radiation of relatively high energy, and the density, composition and velocity of the liquid are measured using different sources, in different sections of the pipeline and without monitoring of radiation sources.

The technical result of the invention is to increase the accuracy and reliability of measurements of the fractional composition and flow rate of a multiphase liquid due to: simultaneous measurement of attenuation of fast neutrons and electromagnetic radiation in the same section, monitoring of a pulsed source of fast neutrons and electromagnetic radiation, the location of the gamma spectrometer and gamma ray detector on one side with a pulsed source of fast neutrons and electromagnetic radiation, and also additionally by measuring shackles of thermal and epithermal neutrons produced in the liquid during deceleration it fast neutrons emitted by pulsed fast neutron source and electromagnetic radiation.

The technical result is achieved in that a multiphase fluid analyzer containing a pulsed source of fast neutrons and a source of electromagnetic radiation, a gamma spectrometer, a gamma ray detector and a scintillator located diametrically to a source of electromagnetic radiation on the opposite side of the pipeline, the pulsed source of fast neutrons is also a pulsed source of electromagnetic radiation further comprising a monitor detector of fast neutrons and a monitor detector of elec magnetic radiation, gamma spectrometer additionally contains a gamma ray collimator and is located next to a pulsed source of fast neutrons and electromagnetic radiation, a gamma ray detector is located on one side of the pipeline with a pulsed source of fast neutrons and electromagnetic radiation at a distance L> V × t from the pulsed source of fast neutrons and electromagnetic radiation in the direction of the multiphase fluid flow, where V is the multiphase fluid flow rate, at is the time of its irradiation, additionally with holds a fast neutron detector located diametrically to a source of fast neutrons and electromagnetic radiation on the opposite side of the pipeline, additionally contains detectors of thermal and epithermal neutrons located from a pulsed source of fast neutrons and electromagnetic radiation at a distance equal to the length of deceleration of fast neutrons in a multiphase liquid, and gamma spectrometer, monitor detector of electromagnetic radiation and scintillator are configured to measure spec pulse electromagnetic radiation.

The drawing shows a diagram of the device, where 1 is the pipeline, 2 is the direction of flow of the multiphase fluid; 3 - pulsed source of fast neutrons and electromagnetic radiation; 4 - scintillator; 5 - fast neutron detector; 6, 7 - detectors of thermal and epithermal neutrons; 8 - gamma spectrometer; 9 - gamma ray detector.

The device consists of: a pulsed source of fast neutrons and electromagnetic radiation 3, which includes a monitor detector of fast neutrons and a monitor detector of electromagnetic radiation (not shown), designed to measure the intensity of radiation coming from a pulsed source of fast neutrons and electromagnetic radiation 3; gamma spectrometer 8, equipped with a gamma ray collimator (not shown) for detecting gamma quanta of inelastic scattering of fast neutrons by the nuclei of atoms located in the irradiation region of a multiphase liquid during a pulse of a pulsed source of fast neutrons and electromagnetic radiation 3 and gamma quanta of radiation capture in the gaps between his impulses; a scintillator 4 and a fast neutron detector 5 for detecting electromagnetic radiation and fast neutrons from a pulsed source of fast neutrons and electromagnetic radiation 3 passed through pipeline 1; thermal detectors 6 and epithermal 7 neutrons generated in a multiphase liquid as a result of slowing down fast neutrons and flowing out of the pipeline 1 outward towards a pulsed source of fast neutrons and electromagnetic radiation 3; a gamma ray detector 9 for detecting gamma rays from the decay of an oxygen-16 nucleus with a half-life T _1/2 = 7.2 s, excited during the pulse of a pulsed source of fast neutrons and electromagnetic radiation 3.

As a pulsed source of fast neutrons and electromagnetic radiation 3, a 14-MeV portable neutron generator can be used, which simultaneously with fast neutrons also emits electromagnetic (X-ray) radiation from the brake spectrum with a maximum energy equal to the accelerating voltage on its accelerating tube and usually more than 100 keV. The energy of fast neutrons emitted by a 14 MeV portable neutron generator exceeds the threshold of the nuclear reaction O ¹⁶ (n, p) N ¹⁶ , which is approximately 10 MeV, which occurs on the oxygen-16 nuclei that make up the multiphase liquid. The product of this reaction, the N ¹⁶ nucleus quickly undergoes beta decay, forming an excited O ¹⁶ nucleus with a half-life of T _1/2 = 7.2 s, which emits gamma rays with an energy of 6.1 MeV in 68.8% of cases.

The distance L between the gamma ray detector 9 and the pulsed source of fast neutrons and electromagnetic radiation 3 is selected based on the estimated flow rate of the multiphase liquid V and the time of its irradiation t <T _1/2 , where T _1/2 is the half-life of the excited oxygen nucleus-16 , from relation (1):

$$L>V\cdot t(\mathrm{one})$$

The gamma ray detector 9 is used to measure the number of gamma rays associated with the activation of oxygen-16 and can be performed, for example, in the form of one / several scintillation gamma radiation detectors containing a photodetector in the form of a photomultiplier and a scintillator crystal, for example, bismuth orthogermanate, bromide lanthanum or BaF ₂ . The gamma ray detector 9 is mounted on one side with a pulsed source of fast neutrons and electromagnetic radiation 3, because fast neutrons in a liquid quickly lose their energy and go into the energy range below the threshold oxygen activation energy - 16 (≈10 MeV) already in a layer about 1 thick cm, leading to a sharp decrease in the amount of activated oxygen-16 as you move away from the pulsed source of fast neutrons and electromagnetic radiation 3.

The multiphase fluid flow rate is determined by the time interval Δt between the moment of termination of the short-term (<1 s) irradiation of the liquid by a pulsed source of fast neutrons and electromagnetic radiation 3 and the appearance of 9 gamma rays emitted from excited oxygen nuclei in the gamma ray detector 16 from the relation:

$$V=L/\Delta t(2)$$

where L is the distance between the pulsed source of fast neutrons and electromagnetic radiation 3 and the gamma ray detector 9, Δt is the time interval between the end of irradiation of a multiphase liquid and the appearance of a signal in the gamma ray detector 9.

The time interval Δt is measured using a multi-channel time analyzer (not shown in the drawing) connected to a gamma ray detector 9 and synchronized with a source of fast neutrons and electromagnetic radiation 3.

The scintillator 4 and the fast neutron detector 5 are located diametrically to the pulsed source of fast neutrons and electromagnetic radiation 3 on the opposite side of the pipeline 1.

The detectors of thermal 6 and epithermal 7 neutrons are located on the side of the pulsed source of fast neutrons and electromagnetic radiation 3 at a distance equal to the length of deceleration of fast neutrons in a multiphase liquid.

Gamma spectrometer 8 is equipped with a gamma ray collimator (not shown in the drawing) and is located next to a pulsed source of fast neutrons and electromagnetic radiation 3.

A monitor detector of electromagnetic radiation (not shown in the drawing) and scintillator 4 are used to measure the attenuation of electromagnetic radiation coming from a pulsed source of fast neutrons and electromagnetic radiation 3, when passing through a pipeline 1 with a multiphase liquid. The measurement results are used to determine the fractional composition of the liquid.

A monitor detector of electromagnetic radiation (not shown in the drawing) and scintillator 4 are configured to measure the spectrum of pulsed x-ray radiation in several energy windows, for example, using a spectrozonal sensor [RF Patent No. 2388015, IPC: G01T 1/00, 2010], which consists of a scintillation plate, extended along the direction of the x-ray beam, a position-sensitive photodetector is located on the side surface of the plate. The measurement of the x-ray spectrum by a spectrozonal sensor is based on the dependence of the spatial distribution of the scintillation signal arising in the photodetector on the radiation spectrum arriving at the end surface of the scintillator plate.

A fast neutron monitor detector (not shown in the drawing) and a fast neutron detector 5 are used to measure the attenuation of fast neutrons when passing through a pipeline 1 with a multiphase liquid. The measurement results are used to determine the fractional composition of the liquid. A fast neutron monitor detector (not shown in the drawing) and a fast neutron detector 5 are configured to detect pulsed radiation of fast neutrons. For this, for example, electrometric sensors [E. Bogolubov, A. Koshelev, V. Mikerov and A. Sviridov, Electrometric sensors for neutron radiation: conceptual study, 2012 JINST 7 C03026; Patent RU No. 2469355, IPC: G01T 3/00, 2012]. The operation of the electrometric sensor is based on measuring the charge arising, for example, in a plate made of calcium isotope Ca ⁴⁰ when it is irradiated with fast neutrons. The charge in the Ca ⁴⁰ wafer arises due to the exit of protons formed in the wafer as a result of a nuclear reaction under the action of fast neutrons: Ca ⁴⁰ (n, p) K ⁴⁰ . The magnitude of the electric charge arising in the plate during the pulse is proportional to the output of fast neutrons per pulse.

The thermal neutron detector 6 and the epithermal neutron detector 7 can be made in the form of helium or boron neutron counters. The epithermal neutron detector 7 is surrounded by a material that absorbs thermal neutrons and transmits epithermal neutrons, for example, a cadmium sheet about 1 mm thick. The thermal neutron detector 6 and the epithermal neutron detector 7 are mounted on one side with a pulsed source of fast neutrons and electromagnetic radiation 3. The effect of the diameter of the pipe 1 on the measurement results is reduced. The thermal neutron detector 6 and the epithermal neutron detector 7 are installed from a pulsed source of fast neutrons and electromagnetic radiation 3 at a distance equal to the deceleration length of 14 MeV neutrons in a multiphase liquid, which is usually about 5-7 cm for carbohydrates.

Gamma spectrometer 8 is used to measure gamma rays of inelastic scattering that occur in a liquid during irradiation with fast neutrons. The measurement method is similar to the method of carbon-oxygen logging [M.A. Fedorin, B.G. Titov // Geology and Geophysics. - 2010. - No. 12. - S.1664-1674]. In this method, a portable 14 MeV neutron generator with a pulse duration of the order of 10 μs and a repetition rate of (10–20) kHz and a scintillation gamma spectrometer are used as the source. In this case, a scintillation crystal is usually used in a gamma spectrometer with a luminescence time much shorter than the duration of a neutron pulse.

Gamma spectrometer 8 is installed on one side with a pulsed source of fast neutrons and electromagnetic radiation 3 and as close to it as possible, since the intensity of gamma rays coming into gamma spectrometer 8 drops sharply with the distance between them. This is due primarily to a decrease in the number of gamma-ray edges produced in a multiphase liquid, with the distance from the pulsed source of fast neutrons and electromagnetic radiation 3 approximately inversely proportional to the square of the distance.

The gamma spectrometer 8 is equipped with a gamma ray collimator (not shown), which serves to prevent gamma rays generated in the source of fast neutrons and electromagnetic radiation 3 during the neutron pulse from entering the gamma spectrometer 8 and to register only those gamma rays that come from areas of irradiation of multiphase fluid. The gamma ray collimator is made of a material that greatly attenuates gamma radiation, usually from lead or tungsten.

The device is installed on the pipeline 1, used for pumping multiphase fluid.

The device operates as follows. A pulsed source of fast neutrons and electromagnetic radiation 3 operates in a frequency mode and irradiates a multiphase liquid flowing through pipe 1 with neutrons with an energy of 14 MeV and electromagnetic (X-ray) radiation from the inhibitory spectrum. Fast neutrons and electromagnetic radiation partially pass through conduit 1, and fast neutrons interacting with the atoms of the substances that make up the liquid, lead to the appearance of gamma radiation of inelastic scattering, activate oxygen and gradually slow down, leading to the appearance of thermal and epithermal neutrons in a multiphase liquid, spreading in all directions.

During a pulse of a pulsed source of fast neutrons and electromagnetic radiation 3, a monitor detector of fast neutrons and a monitor detector of electromagnetic radiation (not shown in the drawing), which are part of a pulsed source of fast neutrons and electromagnetic radiation 3, record the number of 14 MeV neutrons and the spectrum of x-ray radiation from a pulsed source of fast neutrons and electromagnetic radiation 3; a scintillator 4 and a fast neutron detector 5 record the x-ray spectrum and the number of 14 MeV neutrons transmitted through the pipeline 1; gamma spectrometer 8 registers the spectrum of gamma rays arising from inelastic scattering of fast neutrons by atoms of substances that are part of a multiphase liquid, and going towards gamma spectrometer 8.

In the intervals between the pulses of a pulsed source of fast neutrons and electromagnetic radiation 3 gamma spectrometer 8 registers the gamma spectrum of radiation capture of thermal neutrons by atoms of substances that are part of a multiphase liquid; thermal neutron detectors 6 and epithermal neutrons 7 detect thermal and epithermal neutrons generated in a liquid as a result of deceleration of 14 MeV neutrons.

The density and volumetric ratio of multiphase fluid fluids is determined by attenuating the fast neutron beam and the electromagnetic radiation beam using expressions of the form (3) and (4) [RF Patent No. 2334972; IPC: G01N 23/00; 2006]:

$$\mu \cdot d=\ln (I/I_0)\left(3\right)$$

$$\mu =(N_A/A)\cdot \sigma \left(\mathrm{four}\right)$$

where µ is the linear attenuation coefficient of radiation (neutron or electromagnetic); d is the thickness of the layer of substance; I, I ₀ - the intensity of the radiation transmitted through the pipeline and incident on it; N _A is the Avogadro number; A is the atomic weight of the substance through which the radiation passes; σ is the cross section for attenuation of radiation by a substance.

In the case of electromagnetic radiation, the attenuation of radiation is measured in the energy windows for several radiation energies.

The determination of the fractional composition of the liquid by attenuation of fast neutrons and electromagnetic radiation in the same section of the pipeline and at the same time increases the reliability and accuracy of the results.

The concentration of carbon and oxygen nuclei, the presence and content of impurities is determined by the spectrum of gamma quanta of inelastic scattering [Filippov, EM Neutron-neutron and neutron gamma methods in ore geophysics. - Novosibirsk: Science, 1972].

Additionally, the density and amount of hydrogen-containing substance, as well as the content of impurities that absorb thermal neutrons, such as chlorine, are controlled by the flux density of thermal and epithermal neutrons arriving at the thermal neutron detector 6 and the epithermal neutron detector 7.

When measuring the flow rate of a multiphase liquid in pipeline 1, a pulsed source of fast neutrons and electromagnetic radiation 3 is turned on for a time t <1 s, and then turned off. Using a multi-channel time analyzer (not shown in the drawing), the time interval Δt is measured between the end of irradiation of a multiphase liquid in pipeline 1 and the appearance of a signal at the output of the gamma ray detector 9, caused by gamma rays emanating from activated oxygen-16 nuclei. The multiphase fluid flow rate V is determined using expression (2).

The density of the multiphase liquid, its fractional composition and flow rate determine the mass flow rate of the fractions.

Clarify the phase composition and mass flow rate of multiphase fluid fluids by analyzing the entire set of data, taking into account multidimensional relationships between flow characteristics and measured values [Ellansky MM, Enikeev BN The use of multidimensional relationships in oil and gas geology. - M .: Nedra, 1991].

Claims (1)

A multiphase fluid analyzer containing a pulsed fast neutron source and an electromagnetic radiation source, a gamma spectrometer, a gamma ray detector and a scintillator located diametrically to the electromagnetic radiation source on the opposite side of the pipeline, characterized in that the pulsed fast neutron source is also a pulsed electromagnetic radiation source, additionally comprising a monitor detector of fast neutrons and a monitor detector of electromagnetic radiation i, the gamma spectrometer additionally contains a gamma ray collimator and is located next to a pulsed source of fast neutrons and electromagnetic radiation, a gamma ray detector is located on one side of the pipeline with a pulsed source of fast neutrons and electromagnetic radiation at a distance L> V × t from the pulsed source of fast neutrons and electromagnetic radiation in the direction of the multiphase fluid flow, where V is the multiphase fluid flow rate, at is the time of its irradiation, further comprises a fast detector neutrons, located diametrically to a pulsed source of fast neutrons and electromagnetic radiation on the opposite side of the pipeline, additionally contains detectors of thermal and epithermal neutrons located from a pulsed source of fast neutrons and electromagnetic radiation at a distance equal to the slowdown length of fast neutrons in a multiphase liquid, and a gamma spectrometer, the electromagnetic radiation monitor detector and scintillator are configured to measure the spectrum of a pulsed electron magnetic radiation.