WO2009135391A1

WO2009135391A1 - A method and system for determining the constituent content of a multiphase fluid

Info

Publication number: WO2009135391A1
Application number: PCT/CN2009/070257
Authority: WO
Inventors: 罗平安; 贺江林
Original assignee: Luo Pingan; He Jianglin
Priority date: 2008-05-06
Filing date: 2009-01-21
Publication date: 2009-11-12
Also published as: CN101261236A

Abstract

A method for determining the constituent content of a multiphase fluid includes the following step: gamma rays at single-energy or dual-energy levels are produced by a radiation source (2, 6), after said gamma rays pass through the multiphase fluid, the data at each energy level are detected by a detector sub-system which is composed of one or two detectors (4, 8), and the mass percents of the components in the multiphase fluid are calculated by a controlling and data processing sub-system based on the detected data. Said multiphase fluid is a two-phase or three-phase mixture in crude oil or natural gas. The method can be used for automatic on-line measurement of the production in oil or gas well.

Description

Method and system for measuring substance content in multiphase flow

The invention relates to the field of petroleum measurement technology, in particular to a dual-energy gamma ray measurement technology, that is, a gamma ray and a substance interaction principle generated by a radioactive source, in oil and gas field production, oil-water gas, oil sand water, or gas sand water three-phase Under the condition of coexistence of medium, measure the moisture content, oil content, gas content or sediment concentration in the oil and gas pipeline (only three of the four indicators related to the corresponding mixed fluid). Especially suitable for oil and gas field production, automatic online metering system.

Background technique

Crude oil and natural gas are among the most important energy sources. Crude oil natural gas extracted from oil and gas wells is a mixture of multiphase media such as oil, water, natural gas or sand. The treatment of this mixture is first carried out by gas-liquid separation, and the remaining oil-water mixed liquid is subjected to dehydration treatment to obtain a product oil having a low moisture content for external transportation or sale. The sand particles contained in it should also be monitored and separated in time, otherwise the equipment will be easily damaged. In a series of production activities such as crude oil dehydration treatment, it is necessary to timely and accurately grasp the moisture content and gas content of crude oil, so as to control the production process and ensure the production of qualified crude oil. Therefore, indicators such as water content and gas content of crude oil are an important parameter in the process of petroleum collection, smelting and transportation in the petrochemical industry. In particular, many old oilfields currently use water injection and oil recovery processes, and the moisture content of crude oil is generally high. Therefore, the accurate detection of moisture content and gas content (or sediment concentration) in crude oil and natural gas plays an important role in crude oil production and trade.

At present, there are mainly the following methods for measuring the moisture content of crude oil: artificial steam distillation test, microwave method (or radio frequency method), capacitance method, short wave method, heat conduction method, vibration density meter method and γ ray method. 1. The microwave method (such as CN1112677) is based on the interaction between electromagnetic waves and dielectric materials. The dissipation is related to the size and relative dielectric constant of the material. The difference in dielectric constant between oil and water leads to the RF impedance characteristics of the measured object. Differently, when the RF signal is transmitted to the capacitive RF sensor with the oil-water mixture as the medium, the load impedance changes with the different oil-water ratio of the mixed medium, that is, when the moisture content of the crude oil changes, the wave parameter changes accordingly, thereby realizing the water content. Rate measurement; 2, the capacitance method (such as: CN1186236) is based on the difference in dielectric constant of oil and water, reflected in the capacitance of the capacitor composed of the plate, measuring the change in capacitance, you can measure the change in water content; The short-wave method (eg CN2349574) uses a (post) probe to emit a 3. 579MHz short-wave signal into the crude oil, ascertaining the current state of the crude oil, and after a few seconds, transmitting it to the crude oil through another (front) probe. 3. The short-wave signal of 579MHz is taken out of the water-containing signal in the oil, and then the difference measured by the second is taken. The instantaneous moisture content can be obtained after the treatment; 4. The heat conduction method (such as: CN1259671) uses the difference in thermophysical properties of the liquid-liquid two-phase fluid, such as heat conduction, specific heat, viscosity, etc., while measuring the water content and oil-water flow rate of the crude oil. 5. Vibration densitometer method (such as: CN1789969, CN2359692) The liquid level measuring component is used to measure the liquid level of the crude oil in the oil storage tank (or separator), and the pressure measuring instrument measures the crude oil portion in the oil storage tank (or separator). The pressure and the pressure on the bottom are finally calculated by the empirical formula; 6. The ray method (eg, CN86105543A, CN2359692Y, CN1086602A, CN2383068Y) works according to the principle that the gamma rays pass through different media and their attenuation is different. All kinds of measurement methods except gamma ray method are contact type measurement. Due to strong corrosiveness of crude oil, serious scaling and waxing, the reliability of long-term operation of the instrument is poor, especially these instruments cannot eliminate the gas-containing pair. The effect of moisture content measurement leads to a large measurement error. In this regard, the patents CN2452022Y, CN2646704Y and CN2646705Y specifically design different erasers to accumulate impurities outside the sensor. In addition, the change in moisture content measured by the capacitance method, the radio frequency method, and the microwave method is nonlinear, and there is an inflection point in a certain moisture content range, and the crude oil is a mixture of oil, water and gas, and its physical and chemical properties are variable, so The above several measurement methods except the gamma ray method cannot meet the production requirements well in practical applications.

The crude oil water analyzer based on the interaction law between γ-ray and matter has nothing to do with the macroscopic fluid state and chemical properties of the mixed fluid, and can measure the moisture content and gas content of complex crude oil, which is very popular in oil fields.

The invention patent CN86105543A discloses a single energy γ emitted by a radiation source such as ^1M Cd, or ²⁴³ Am, etc. Ray, the principle of measuring the volumetric moisture content of a two-phase oil-water mixture. Utility model patent CN2359692Y discloses a device for measuring the moisture content of a two-phase oil-water mixture using a ²³⁸ Pu source. The invention patent CN1086602A discloses an automatic measuring instrument for measuring gas content and water content in crude oil in a three-phase oil-water-gas mixture; Y-rays are respectively fixed on both sides of a symmetric position along a radial center line on a side wall of the measuring pipe a source and a transmission detector; a scattering detector is fixed on a side wall of the center line at an angle to the center line of the Y-ray source and the transmission detector and at a distance from the axial direction of the measuring tube; finally, according to the measurement result, The volumetric gas content and volumetric water content are obtained after data processing. The utility model patent CN2383068Y improves the device designed according to the above principle, and adds a stirring device to uniformly mix the oil and water from the oil well to further satisfy the theoretical assumptions, so as to improve the measurement accuracy. In any case, this theoretical model takes too many approximations. The physical meaning of each parameter is not clear. The influence on the parameters such as pressure and temperature is not considered. These ultimately affect the method and measurement accuracy.

For the measurement of sediment concentration, GB 2429288A has published a patent for measuring the sediment concentration by acoustic method. That is, by the collision of the sand with the oil or gas pipeline wall, the amount of sediment in the fluid is calculated. The equipment designed by the patent has a simple structure, convenient installation, low power consumption, long time to save data locally, and the like. However, the working frequency band of this principle belongs to audio, and its interference source is more and more complicated. The measurement result is also susceptible to the fluid flow property. Therefore, the measurement uncertainty is relatively large, which cannot meet the needs of high-precision measurement.

At present, the method and device for measuring the gas content, oil content, water content or sediment concentration in crude oil by the dual-energy gamma ray method with relatively accurate and relatively complete measurement theoretical model have not been found on the market, thus sacrificing the performance of the measurement system.

Summary of the invention

The object of the present invention is to provide a crude oil in a three-phase oil-water gas or oil-water sand or a mixture of water-gas sand, real-time high-precision measurement of water content, oil content, gas content or sediment content in crude oil or natural gas, and proposed crude oil. (Natural gas) Two-energy gamma ray measurement method for gas content, water content, oil content or sediment concentration (only three of the four indicators related to the corresponding mixed fluid can be measured). The theoretical model of the invention has high precision, the physical meaning of various parameters is relatively clear, the use is simple, and the influence of temperature, pressure and the like can also be considered, and is particularly suitable for automatic online metering system in oil field production.

The invention provides a dual energy gamma ray measuring method for a substance content in a three-phase mixture, wherein the three-phase mixture is a combination of any three of oil, water, gas and sand contained in crude oil or natural gas.

The steps of the measuring method are:

(1) generating dual-energy gamma rays from a radioactive source;

(2) The emitted gamma rays pass through the three-phase mixture;

(3) after the dual-energy gamma ray passes through the three-phase mixture, the high-energy and low-energy two-stage data is detected by the detector subsystem;

(4) The measured high energy and low energy data, the following algorithm is used to solve the content of the corresponding three substances in the three-phase mixture; the algorithm is:

ω _λ , « ₂ and ₃ respectively correspond to the weight percentage of the three substances in the mixture. From the physical meaning, ω ₂ = \ - ω _ι - ω ω _χ and ₃ can be solved according to the measured data by the following two equations:

In the equation: E _H , respectively representing the energy corresponding to the high-energy γ-ray and low-energy γ-ray emitted by the γ-radiation source; ρ represents the actual density under the three-phase mixture, and the pure substance under the conditions of temperature, pressure and the like corresponding to the actual tube The density of 1 , p ₂ represents the density of pure substance 2 under the conditions of temperature and pressure corresponding to the actual tube, and p ₃ represents the density of pure substance 3 under the conditions of temperature, pressure and the like in the actual tube; _μι , μ ₂ , ^ represents the linear attenuation coefficient of pure substance 1, pure substance 2, and pure substance 3 at the corresponding gamma ray energy; X represents the linear thickness of the measurement space of the test system; (Ε) Represents the count measured by the test system in the absence of any substance in the tube under the corresponding gamma ray energy conditions; Ν ( X , Ε) represents the test system under the corresponding measured thickness and gamma ray energy conditions counting measurements; or the Epsilon is _Ε Η _{_{Ε ί; μι, μ 2,}} μ 3 can be determined by previously measuring the profile exponential decay, also be obtained by checking the data sheet.

Further, when the three-phase mixture is a three-phase mixture of oil, water and gas in crude oil or natural gas, the meanings of W, " ₂ and « ₃ are: ω _χ - moisture content, ω ₂ - oil content, ω ₃ —-gas content;

The water content, the oil content and the gas content can be determined according to the method of claim 1.

Further, when the three-phase mixture is a three-phase mixture of oil, water and sand in crude oil, the specific meanings of " ₂ and " ₃ are:

ω _χ —— moisture content, ω. - oil content, ω ₃ - sediment concentration;

The water content, oil content and sediment content can be determined according to the method of claim 1.

Further, when the three-phase mixture is a three-phase mixture of gas, water and sand in natural gas, the specific meanings of " ₂ and " ₃ are:

ω _χ - moisture content, ω. - gas content, ω ₃ - sediment concentration;

The moisture content, gas content and sand content can be determined according to the method of claim 1. Further, the high energy energy source γ _Ε Η range between 10keV~lMeV, low energy satisfy the relationship E _H «(1. 5~3), or from E _H« 2.

Further: When one of ω ₂ and ₃ is zero, the gamma ray emission of the measurement system produces a single energy gamma ray, and the following formula is used to solve the percentage of substance 1 and the percentage of substance 2 ί3⁄4:

ω ₂ = \ - ω

In the formula: ρ represents the actual density in the two-phase state of the tubing, _Pl represents the density of the substance 1 under the conditions of temperature and pressure corresponding to the actual tubing, and ρ ₂ represents the substance under the conditions of temperature, pressure and the like corresponding to the actual tubing. The density of 2; ^, μ ₂ represent the linear attenuation coefficient of substance 1, substance 2 under the corresponding gamma ray energy; χ represents the linear thickness of the measurement space of the test system; Represents the count measured by the test system when there is no substance in the tubing under the corresponding gamma ray energy condition; Ν ( X ) represents the count measured by the test system under the corresponding measured thickness and γ ray energy; , μ ₂ can be obtained by measuring the exponential decay curve in advance, or by checking the data sheet.

In order to simplify the writing process, if not specified, only the coexistence of oil, water and gas three-phase mixture is considered in the following discussion. For the other three coexistence cases, the processing skills are similar, and only the relevant formulas need to be replaced in the illustrated formula. The physical quantity is sufficient, so the process of explaining the other cases is omitted.

The dual-energy gamma ray measurement method for the gas content and water content in crude oil is based on the principle of gamma ray and material interaction generated by the radioactive source. In the oil field production, the water content in the oil pipeline is measured under the condition that the oil, water and gas three-phase medium coexist. Gas rate indicator. The measurement method relies on a measuring device consisting mainly of three large-division systems and a set of special software, that is, it includes two kinds of gamma-ray gamma-ray sources that generate two kinds of energy, one or two sets of detectors constitute detectors. The system, and a master control and data processing subsystem; the other device further includes a collimator; the detector subsystem includes a detector, a preamplifier or a photomultiplier tube, signal shaping, amplification, sample and hold, AD conversion, etc. Unit; The total control and data processing subsystem includes data transmission, synchronization, display, control and alarm; the special software solves the water content and the gas content by algorithm

«Indicating the weight percentage of water is the water content, " ₃ means the weight percentage of natural gas, ie the gas content, ί3⁄4 means the weight percentage of oil: iy^l- - iy^ in the three-phase state of oil, water and gas, The special software uses the following two equations to solve the water content 6^ and the gas content rate ω. In the equation: the corresponding high-energy γ-ray and low-energy γ-rays corresponding to the γ-ray source respectively represent the actual density in the three-phase state of the oil-water gas in the oil pipe, and Pi represents the temperature and pressure corresponding to the actual oil pipe. The density of pure water, p ₂ represents the density of pure crude oil under the conditions of temperature and pressure corresponding to the actual oil pipe, and p ₃ represents the density of pure natural gas under the conditions of temperature and pressure corresponding to the actual oil pipe; ^, μ ₂ , μ ₃ represents the linear attenuation coefficient of pure water, pure crude oil and pure natural gas under the corresponding γ ray energy; X represents the linear thickness of the measurement space in the test tube; Ν. ( Ε ) represents the count measured by the test system when there is no substance in the tubing under the corresponding gamma ray energy conditions; Ν ( X , Ε ) represents the test system under the corresponding measured thickness and γ ray energy conditions counting measurements; Epsilon herein refers _Ε Η or _{_{Ε Ί; ΜΙ, μ 2,}} μ 3 can be determined by previously measuring the profile exponential decay, also be obtained by checking the data sheet.

When only the oil-water two-phase state is considered, the gamma ray source of the measurement system can be simplified into an energy gamma ray source. At this time, the following formula is used in the special software to solve the water content W.

In the formula: p represents the actual density of the oil-water two-phase state in the oil pipe, _Pl represents the density of pure water under the conditions of temperature and pressure corresponding to the actual oil pipe, and p ₂ represents the temperature and pressure corresponding to the actual oil pipe. The density of pure crude oil; ^, ^ represents the linear attenuation coefficient of pure water and pure crude oil under the corresponding γ ray energy; X represents the linear thickness of the measurement space in the test tube; Ν. Represents the gamma] ray energy corresponding to the conditions, the tubing there is no presence of any material, test system counts measured; Ν (X) represents the corresponding measurement of the thickness, gamma] ray energy conditions, the test system counts _measured; μι , μ ₂ can be obtained by measuring the exponential decay curve in advance, or by checking the data sheet.

When designing a radioactive source system, it is considered that certain conditions should be met between high and low energy, which will affect the measurement accuracy. The higher the difference between high energy Ε _Η and low energy EL, the better the measurement accuracy, for example: E _h « (1. 5~3) EL, simpler, E„«2E _L , the energy range of high energy γ ray can be taken at 10keV~lMeV between.

The dual-energy gamma ray measurement technology of the invention improves the measurement accuracy of the measurement system by using a relatively perfect physical model, and is suitable for an automatic online metering system in oil field production. The theoretical model has high precision, and the various parameters have clear physical meanings and are simple to use, taking into account the influence of temperature and pressure. When the dual-energy gamma ray source is utilized, the system can be simplified and the reliability of the measurement system can be improved while ensuring high measurement accuracy, which is of great significance for the measurement and measurement of crude oil production.

For the case where the oil, water and gas three-phase mixture coexist, the detailed theoretical basis of the measuring method of the present invention is derived as follows:

If the substance is a mixture with a density of ρ, a linear attenuation coefficient of μ, and a mass attenuation coefficient of the element contained, then the mass attenuation coefficient of the mixture is calculated by:

1 [pj

Where ω ₂ , ..., ω _τ ..., ί are the weight percentages of the constituent elements, respectively.

Note: The mass attenuation coefficient of an element can also be expressed as μ„, the linear thickness is χ, and the mass thickness is .

χ χ- ρ

Ρ

1. Consider the oil-water two-phase state (ie: the gas phase content is 0. At this time, there is no subscript a crude oil + water mixed state, subscript 1 - pure water state, subscript 2 - pure crude oil state)

= +(!-«1)^2

= W(H ₂ )+ ^ ₂ (2)

For a single-energy gamma source, its law of action with matter obeys the law of exponential decay.

N(x _m ) = N ₀ e-^ (4)

Where: N. The count of measurements after a ray passes through the air.

After N (x _m )-ray passes through a mass of material with a thickness of x _m , the measured count,

Substituting (3) into (4) and simplifying it:

In this case, an unknown water content c3⁄4, an equation, can solve the measurement problem by using a single energy, which is the method for measuring the single energy measurement in the two-phase state of the present invention.

2. Consider the three-phase state of oil, water and gas (no subscript a crude oil + water + gas mixed state, subscript 1 - pure water state, subscript 2 - pure crude oil state, subscript 3 - pure natural gas state) ^X m = ^Χ ·Ρ

, Α Pi ,

Source of monoenergetic γ in terms of its action rule exponential attenuation law material _t

N(x _m ) = N ₀ e-^ (8)

Substituting (8) into (7) and simplifying it:

In order to obtain the water content "and the gas content i3⁄4, two equations similar to (9) need to be listed. From nuclear physics, it can be measured by two different energy rays. (Note: Some literatures introduce the relationship between scattered ray and matter to obtain the second equation, but the equations are relatively fuzzy, and the physical meaning of each parameter is not clear.) In this paper, the dual energy measurement model is discussed as follows: :

Let E _H and EL represent the energy corresponding to high energy and low energy γ ray, respectively, then (9) can be expressed as:

Theoretically, ω^Ρί3⁄4 can be obtained according to equations (10) and (11), which is a method for testing the moisture content and gas content of the dual energy gamma ray, that is, the special algorithm used in the present invention.

Note:

1) When measuring Pi, ρ ₂ , ρ^Βρ in the experiment, it is necessary to simultaneously detect the influence of parameters such as temperature and pressure of the sample.

2) Since the state of the gas is closely related to temperature and pressure, in application, p ₃ and μ are required to be consistent with the actual conditions.

3) When solving the equation, the actual corresponding ρ value should be used, which can be obtained by real-time measurement.

4) The higher the difference between high energy Ε _低 and low energy EL, the better the measurement accuracy. For example: E _H «(1. 5~3)EL, simpler, E _H =2E _L .

detailed description

The invention is further described below in conjunction with the drawings and specific embodiments.

The present invention also provides a measurement system for the above measurement method, which is composed of the following sub-systems: a radiation source that produces one or two energy gamma rays, a detector subsystem consisting of one or two detectors, a control and data processing Sub-system.

Further, the two sources of energy gamma rays are two independent single-energy gamma ray sources, which are placed at an angle Θ on the same cross section of the measuring pipe, 0 < Θ < 180 °, resulting in a high High-energy and low-energy data measured by the corresponding first set of detectors (4) and second set of detectors (8) after the low-energy gamma rays pass through the three-phase mixture. Further, the two sources of energy gamma rays are two independent single-energy gamma ray sources (2) and (6), which are sequentially placed in parallel on the measuring pipeline, and the intervals of the two sets of detecting paths are L, 0< L < 10m, high energy and low energy data measured by the corresponding first set of detectors (4) and second set of detectors (8).

Further, the two sources of energy gamma rays are radioactive sources (2) and (6) positioned side by side or overlapping, and the high energy and low energy mixed energy spectra measured by the corresponding first group of detectors (4) The identification of high and low energy data is distinguished by gamma ray energy spectrum analysis.

DRAWINGS

Figure 1 is a schematic view showing the lateral installation of two radiation sources and detectors;

Figure 2 is a schematic view showing the longitudinal installation of two radiation sources and detectors;

Figure 3 is a schematic diagram of the parallel placement of two sources and the installation of the detector.

In the figure: 1 a measuring device; 2 - high energy gamma ray source; 3 - collimator and shielding room of high energy gamma ray source; 4 a first group of detectors; 5 - a shielding tube of the first group of detectors; 6—low-energy γ-ray source; 7—collimator and shielded chamber of low-energy γ-ray source; 8—second group of detectors; 9-second group of detectors; 10—crude oil pipeline; 20—( First) signal shaping, amplification and sample-and-hold unit; 21—second signal shaping, amplification and sample-and-hold unit; 22—(first group) detector high voltage power supply; 23—second group detector high voltage power supply ; 24- (first) AD conversion unit; 25 - second AD conversion unit; 26 - (first) control unit; 27 - second control unit; 28 - computer; 30 ^ radioactive source subsystem Control system. According to the measuring method of the present invention, an application example of the following three measuring systems is given:

Example 1 : How the two radiation sources and detectors work in a lateral installation mode

The installation position of the core components of the measuring device 1 is as shown in Fig. 1.

This embodiment is characterized in that two gamma ray sources are used to generate high and low energy gamma rays. The high-energy gamma ray source 2, the collimator 3, the detector 4 and the shielding tube 5 constitute a set of high-energy gamma ray detection paths, the same low-energy gamma ray source 6, collimator 7, detector 8 and shielding tube 9 constitute a set of low-energy gamma ray detection channels. The two sets of detection paths reduce the length of the measuring device 1 on the same cross section of the crude oil pipe 10. Note that the angle between the two sets of detection paths shown in Figure 1 does not necessarily require 90°, as long as the test components are fully installed and the two detection paths are not affected. This example requires that the fluids have approximately the same cross-sectional distribution in the same cross-section of the crude oil conduit 10, so as to satisfy the ideal requirement that the high- and low-energy gamma rays can be simultaneously placed in the same position of the medium. In practical applications, before the medium flows into the test equipment, measures can be taken to stir the fluid and mix it evenly.

The high energy gamma ray source 2 emits high energy gamma rays which, after passing through the collimator and the shield chamber 3, pass through the medium in the crude oil conduit 10 and are converted into electrical signals by the first set of detectors 4. The shield tube 5 of the first set of detectors serves to protect the first set of detectors 4 while reducing the effects of the background and scattered signals on the first set of detectors 4. The high voltage power source 22 of the first group of detectors supplies the first group of detectors 4 with operating voltage, and the signals of the first group of detectors 4 are output to the first signal shaping, amplification and sample and hold unit 20, after the signals are amplified and processed, It is sent to the first AD conversion unit 24 to be converted into a digital signal, and finally sent to the computer 28 for analysis processing. The first way control unit 26 is used to synchronize, coordinate, and work with the various units of the first path and the subsystems associated therewith.

Similarly, the low-energy gamma-ray source 6 emits low-energy gamma rays, passes through the collimator and the shielded chamber 7, passes through the medium in the crude oil pipeline 10, and is converted into an electrical signal by the second group of detectors 8. The shield tube 9 of the second set of detectors serves to protect the second set of detectors 8, while reducing the effects of the background and scattered signals on the second set of detectors 8. The high voltage power supply 23 of the second group of detectors supplies the working voltage to the second group of detectors 8, and the signals of the second group of detectors 8 are output to the second signal shaping, amplification and sample and hold unit 21, after the signals are amplified and processed, It is sent to the second AD conversion unit 25 to be converted into a digital signal, and finally sent to the computer 28 for analysis processing. The second control unit 27 is used to synchronize and coordinate the work of the various units of the second path and the subsystems associated therewith.

The detected dual energy signals are transmitted to the computer 28 for analysis and processing. Computer-specific software application The model derived in the present invention (other suitable models may also be used) is used to calculate indicators such as water content and gas content in the crude oil. Example 2: How the two radioactive sources and detectors are installed in a longitudinal installation mode

The installation position of the core components of the measuring device 1 is as shown in Fig. 2.

This application example is characterized by the use of two sources to generate high and low energy gamma rays. The high-energy gamma ray source 2, the collimator 3, the detector 4 and the shielding tube 5 form a set of high-energy gamma ray detection paths, and the same low-energy gamma ray source 6, collimator 7, detector 8 And the shielding tube 9 constitutes a set of low-energy gamma ray detecting passages. The closer the two sets of detection paths are, the better the ideal requirement is that theoretically high and low energy gamma rays can be simultaneously placed in the same position of the medium. In practice, the parameters can be adjusted according to the uniformity of the medium, the flow rate, the interval of the monitoring data, etc., to ensure that the test conditions satisfy the theoretical model and the error requirements as much as possible.

After the detected dual-energy signals are transmitted to the computer 28 respectively, special parameters are used, and the models derived in the present invention (other suitable models can also be used) are used to calculate the moisture content and gas content in the crude oil. Example 3: How the two radioactive sources are placed in parallel to measure the working principle of the system

The installation position of the core components of the measuring device 1 is as shown in Fig. 3.

This application example is characterized in that two gamma ray sources 2 and 6 are juxtaposed at the position aligned with the exit of the collimator 3, and high and low gamma rays are randomly emitted from the exit of the collimator 3. Using the energy spectrum analysis function of the dedicated software, the energy range of high-energy and low-energy γ-rays is marked, and the counts of high-energy and low-energy γ-rays are recorded separately, and used as high- and low-energy channel data.

The high and low energy gamma rays emitted by the radiation sources 2 and 6, respectively, randomly but not simultaneously pass through the collimator 3, illuminate the medium in the crude oil pipe 10, and are converted into electrical signals by the detector 4. The shield tube 5 of the detector serves to protect the detector 4 while reducing the influence of the detection background and the scattered signal on the detector 4. The detector's high voltage power supply 22 supplies the detector 4 with an operating voltage. The detector 4's signal is output to the signal shaping, amplification and sample and hold unit 20. The signal is amplified, processed, and sent to the AD conversion unit 24 for conversion to a digital signal. It is sent to the computer 28 for analysis processing. The control unit 26 is used to synchronize and coordinate the work of each unit or subsystem.

In this example, the same set of detector systems common to sources 2 and 6 are distinguished by high- and low-energy gamma spectroscopy.

The detected dual energy signals are transmitted to the computer 28 for analysis and processing. The computer-specific software then applies the model derived in the present invention (other suitable models can also be used) to calculate the water content, gas content and the like in the crude oil.

Claims

Claim

A dual-energy gamma ray measuring method for a substance content in a three-phase mixture, the three-phase mixture being a combination of any three of oil, water, gas and sand contained in crude oil or natural gas, characterized in that:

The steps of the measuring method are:

(1) generating dual-energy gamma rays from a radioactive source;

(2) The emitted gamma rays pass through the three-phase mixture;

(3) after the dual-energy gamma ray passes through the three-phase mixture, the high-energy and low-energy two-group data are detected by the detector subsystem;

ω _λ , « ₂ and ₃ respectively correspond to the weight percentage of the three substances in the mixture, ί3⁄4 = 1 - - ί3⁄4

ω _λ and ₃ can be solved by the following two equations based on the measured data:

In the equation: E _H , representing the energy corresponding to the high energy γ ray and low energy γ ray emitted by the γ source; ρ represents the actual density under the three-phase mixture, representing the pure substance under the conditions of temperature, pressure and the like corresponding to the actual tube. The density of 1 , p ₂ represents the density of pure substance 2 under the conditions of temperature and pressure corresponding to the actual tube, p ₃ represents the density of pure substance 3 under the conditions of temperature, pressure and the like in the actual tube; _μι , μ ₂ , μ ₃ represents the linear attenuation coefficient of pure substance 1, pure substance 2, and pure substance 3 under the corresponding gamma ray energy; X represents the linear thickness of the measurement space of the test system; N _Q ( E ) represents the corresponding γ ray energy The count measured by the test system when there is no substance in the tube; Ν ( χ, Ε) represents the count measured by the test system under the corresponding measured thickness and gamma ray energy; the Ε is Ε _Η Or EL; μι μ ₂ , μ ₃ can be obtained by measuring the exponential decay curve in advance, or by checking the data sheet.

2. The dual energy gamma ray measuring method for material content in a three-phase mixture according to claim 1, wherein the three-phase mixture is a three-phase mixture of oil, water and gas in crude oil or natural gas, the W , ₂ and ₃ The specific meaning is:

W...-water content,

33⁄4...-oil content,

« ₃ — - Gas content.

3. The dual energy gamma ray measuring method for material content in a three-phase mixture according to claim 1, wherein the three-phase mixture is a three-phase mixture of oil, water and sand in crude oil, said W, " ₂ and The specific meaning of " ₃ " is:

W...-water content,

33⁄4...-oil content,

33⁄4... - Sand content.

4. The dual energy gamma ray measuring method for material content in a three-phase mixture according to claim 1, wherein the three-phase mixture is a three-phase mixture of gas, water and sand in natural gas, the w, " ₂ And the specific meaning of " ₃ " is:

W...-water content,

33⁄4...- gas content,

... - the amount of sand.

The dual-energy γ-ray measuring method matter content of the three-phase mixture as claimed in claim 1, wherein: a range of high energy γ _Ε Η energy source between 10keV~lMeV, low-energy EL satisfy the relationship EJH; 1.5 ~3) EL, or E _h -2EL.

6. The dual energy gamma ray measuring method for substance content in a three-phase mixture according to claim 1, wherein: when one of w, ω ₂ and ί3⁄4 is zero, the gamma ray emission of the measuring system generates a single energy For gamma rays, the following formula is used to solve the percentage of substance 1 and the percentage of substance 2 ί3⁄4:

ω ₂ = \ - ω In the formula: p represents the actual density in the two-phase state of the tubing, _Pl represents the density of the substance 1 under the conditions of the temperature and pressure corresponding to the actual tubing, and p ₂ represents the substance under the conditions of temperature, pressure and the like in the actual tubing. 2 - density; ^, μ ₂ represent the linear attenuation coefficient of substance 1, substance 2 under the corresponding gamma ray energy; X represents the linear thickness of the measurement space of the test system; No represents the oil pipe under the corresponding gamma ray energy condition The count measured by the test system when there is no substance present; Ν ( X ) represents the count measured by the test system under the corresponding measured thickness and γ ray energy; μ _ΐ , μ ₂ can be obtained by measuring the exponential decay curve in advance Yes, it can also be obtained by checking the data sheet.

7. A measurement system for use in the measurement method of claim 1 wherein:

It consists of a sub-system as follows: a source of one or two energy gamma rays, a detector system consisting of one or two detectors, a control and data processing subsystem.

8. The measurement system according to claim 7, wherein: the two sources of energy gamma rays are two independent single-energy gamma ray sources, forming one on the same cross section of the measuring pipe. Angle Θ placement, 0<θ<180°, the high energy sum measured by the corresponding first set of detectors (4) and the second set of detectors (8) after the high and low energy gamma rays are passed through the three phase mixture Low energy data.

9. The measurement system according to claim 7, wherein: the two sources of energy gamma rays are two independent single-energy gamma ray sources (2) and (6) on the measuring pipeline. Placed in parallel in parallel, the interval between the two sets of detection paths is L, 0 < L < 10 m, and the high energy and low energy data measured by the corresponding first set of detectors (4) and the second set of detectors (8).

10. The measurement system according to claim 7, wherein: the two sources of energy gamma rays are radioactive sources (2) and (6) placed side by side or overlapping, by a corresponding first group The high-energy and low-energy mixed energy spectra measured by the detector (4), the identification of high and low energy data is distinguished by gamma ray energy spectrum analysis.

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Correction page (Article 91)