Calibration Method of Nuclear Magnetic Resonance Flowmeter for Multiphase Flow

Abstract

The present invention provides a calibration method for a multiphase flow nuclear magnetic resonance flowmeter, the method comprising: sampling a multiphase flow to be measured to obtain a multiphase flow sample; measuring the first amplitude of a free decay signal corresponding to the multiphase flow to be measured and the multiphase flow sample using a multiphase flow nuclear magnetic resonance flowmeter, and determining the gas-liquid volume ratio of the multiphase flow to be measured and the hydrogen index of each phase fluid based on the first amplitude of the free decay signal; transmitting a pulse sequence to the multiphase flow to be measured using a multiphase flow nuclear magnetic resonance flowmeter to measure an attenuation curve, determining a transverse relaxation time based on the attenuation curve, and determining an effective attenuation curve interval and a component content ratio of the multiphase flow to be measured based on the transverse relaxation time. The present invention realizes the application of nuclear magnetic resonance fluid detection technology to industrial measurement sites, performs online, green, non-invasive, full-scale detection of complex fluid flow, and realizes on-site calibration before the instrument is used.

Description

Technical Field

[0001] The invention relates to the technical field of calibration of multiphase flow nuclear magnetic resonance flowmeters, in particular to a calibration method of multiphase flow nuclear magnetic resonance flowmeters. Background Art

[0002] Complex fluids containing multiple components are very common in the industrial field, and their accurate measurement has always been a major problem that has troubled the industry. Taking the oil industry as an example, with the increasing depletion of conventional oil and gas resources and the deepening development of unconventional oil and gas resources, the underground fluids faced by the oil drilling and production engineering field are mainly oil-water two-phase mixed fluids. In oil production, for many years, oil-water two-phase measurement, especially online measurement, has been a global problem and progress has been slow. The commonly used water content measurement technology on site is to sample and let it stand for a period of time, and then read the various contents after the oil and water are separated. This method has many shortcomings: (1) low accuracy and large human influence factors; (2) low efficiency; (3) additional labor costs; (4) in most cases, the sample is directly dumped after the measurement is completed, which pollutes the environment, and for gas wells, sampling has certain safety risks. With the improvement of refined management of oil and gas reservoirs and safety and environmental protection requirements, traditional measurement methods can no longer meet the requirements, and there is an urgent need for efficient, accurate, green and safe measurement methods.

[0003] Nuclear magnetic resonance (NMR) technology is currently a mainstream indoor fluid composition analysis technique. Its advantages lie in its non-invasive, environmentally friendly, efficient, and accurate measurement method. Its application in industrial sites for online measurement of complex mixed-phase fluids holds great promise. The multiphase flow nuclear magnetic resonance flowmeter, developed against this backdrop, represents the first application of NMR technology in oil and gas metering.

[0004] From successful development to field application, multiphase NMR flowmeters undergo two steps: indoor laboratory calibration and field calibration. Indoor calibration primarily calibrates the equipment's basic NMR parameters and verifies measurement accuracy, while field calibration adjusts the device's measurement parameters based on specific well properties (such as gas-liquid ratio, oil-water ratio, pressure, and crude oil viscosity) to ensure stability, efficiency, and accuracy during normal operation. Unlike indoor calibration, field calibration is not allowed to disrupt production and requires a shorter calibration timeframe (less than a few hours). Therefore, the timeliness of the calibration method is highly critical.

[0005] At present, there is no relevant technology in China. In the international oil industry, only Shell of the Netherlands has developed a set of NMR multiphase flowmeters, which includes a method for measuring the flow rate of three-phase flow of oil, gas and water, but has not announced its on-site calibration method. Summary of the Invention

[0006] The main purpose of the embodiments of the present invention is to provide a calibration method for a multiphase flow nuclear magnetic resonance flowmeter, so as to realize rapid calibration and calibration of the oil, gas and water multiphase flowmeter before actual measurement, and prevent flow measurement deviation caused by differences in the properties of the measured fluids.

[0007] To achieve the above objectives, an embodiment of the present invention provides a calibration method for a multiphase flow nuclear magnetic resonance flowmeter, the method comprising:

[0008] Sampling the multiphase flow to be measured to obtain a multiphase flow sample;

[0009] Measuring the first amplitude of the free decay signal corresponding to the multiphase flow to be measured and the multiphase flow sample using a multiphase flow nuclear magnetic resonance flowmeter, and determining the gas-liquid volume ratio of the multiphase flow to be measured and the hydrogen index of each phase fluid based on the first amplitude of the free decay signal;

[0010] A multiphase flow nuclear magnetic resonance flowmeter is used to emit a pulse sequence to the multiphase flow to be measured to measure an attenuation curve, a transverse relaxation time is determined according to the attenuation curve, and an effective attenuation curve interval and a component content ratio of the multiphase flow to be measured are determined according to the transverse relaxation time.

[0011] Optionally, in one embodiment of the present invention, the method further includes: separating the oil and water in the multiphase flow sample to obtain a single-phase oil sample and a single-phase water sample; using a multiphase flow nuclear magnetic resonance flowmeter to detect pure water, the single-phase oil sample and the single-phase water sample to obtain the first amplitude values ​​of the magnetization vectors corresponding to the pure water, the single-phase oil sample and the single-phase water sample; and determining the hydrogen content index corresponding to the single-phase oil sample and the single-phase water sample based on the first amplitude values ​​of the magnetization vectors.

[0012] Optionally, in one embodiment of the present invention, separating the oil and water in the multiphase flow sample to obtain a single-phase oil sample and a single-phase water sample includes: using a static method or centrifugal technology to separate the multiphase flow sample to obtain a single-phase oil sample and a single-phase water sample.

[0013] Optionally, in one embodiment of the present invention, the use of a multiphase flow nuclear magnetic resonance flowmeter to measure the first amplitude value of the free decay signal corresponding to the multiphase flow to be measured and the multiphase flow sample, and determining the gas-liquid volume ratio of the multiphase flow to be measured and the hydrogen content index of each phase fluid based on the first amplitude value of the free decay signal includes: using a multiphase flow nuclear magnetic resonance flowmeter to measure the first amplitude value of the free decay signal of the multiphase flow sample; connecting the multiphase flow to be measured to the fluid pipe of the multiphase flow nuclear magnetic resonance flowmeter so that the multiphase flow to be measured flows continuously under the probe of the multiphase flow nuclear magnetic resonance flowmeter, and using the multiphase flow nuclear magnetic resonance flowmeter to measure the first amplitude value of the free decay signal of the multiphase flow to be measured; determining the gas-liquid volume ratio of the multiphase flow to be measured and the hydrogen content index of each phase fluid based on the first amplitude value of the free decay signal corresponding to the multiphase flow to be measured and the multiphase flow sample, and the first amplitude value of the magnetization vector of the pure water.

[0014] Optionally, in one embodiment of the present invention, the method further includes: performing temperature control using a temperature control device of the multiphase flow nuclear magnetic resonance flowmeter according to the actual ambient temperature; after the current temperature reaches the preset operating temperature of the multiphase flow nuclear magnetic resonance flowmeter, the multiphase flow nuclear magnetic resonance flowmeter sends a pulse sequence to the multiphase flow to be measured to obtain a free decay signal curve; and adjusting the pulse frequency of the multiphase flow nuclear magnetic resonance flowmeter using the free decay signal curve and the magnet frequency of the multiphase flow nuclear magnetic resonance flowmeter at the current temperature.

[0015] Optionally, in one embodiment of the present invention, the attenuation curve is measured by emitting a pulse sequence to the multiphase flow to be measured using a multiphase flow nuclear magnetic resonance flowmeter, and the transverse relaxation time is determined based on the attenuation curve, including: emitting a pulse sequence to the multiphase flow to be measured using a multiphase flow nuclear magnetic resonance flowmeter, measuring the attenuation curve, and inverting the attenuation curve to obtain the transverse relaxation time.

[0016] Optionally, in one embodiment of the present invention, determining the effective attenuation curve interval based on the transverse relaxation time includes: obtaining the fluid velocity of the multiphase flow to be measured based on the transverse relaxation time; and determining the effective attenuation curve interval on the attenuation curve using the fluid velocity of the multiphase flow to be measured.

[0017] The present invention applies nuclear magnetic resonance fluid detection technology to industrial measurement sites, performs online, green, non-invasive, full-range detection of complex fluid flow, and realizes on-site calibration of the instrument before use, facilitating accurate detection of multiphase fluid flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a flow chart of a calibration method for a multiphase flow nuclear magnetic resonance flowmeter according to an embodiment of the present invention;

[0020] Figure 2 Flowchart of the on-site sampling and calibration process in an embodiment of the present invention;

[0021] Figure 3 This is a flow chart for determining the gas-liquid volume ratio and hydrogen index in an embodiment of the present invention;

[0022] Figure 4 A flow chart of determining a pulse frequency according to an embodiment of the present invention;

[0023] Figure 5 This is a flow chart of determining an effective attenuation curve interval in an embodiment of the present invention;

[0024] Figure 6 This is a calibration flow chart of a multiphase nuclear magnetic resonance flowmeter in a specific embodiment of the present invention;

[0025] Figure 7 Schematic diagram of the valve layout of the multiphase flow nuclear magnetic resonance flowmeter in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] An embodiment of the present invention provides a calibration method for a multiphase flow nuclear magnetic resonance flowmeter, which is applicable to industrial fields involving the measurement of flowing fluids.

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] In order to realize the online measurement of oil, gas and water multiphase fluid flow using the NMR method at the oil and gas field site, the calibration method of the multiphase flow nuclear magnetic resonance flowmeter proposed in the present invention can realize the rapid calibration and calibration of the oil, gas and water multiphase flowmeter before actual measurement, prevent the flow measurement deviation caused by differences in the measured fluid properties, and provide method support for NMR flowmeters, which are truly online fluid metering devices that do not require multiphase separation.

[0029] like Figure 1 FIG2 is a flow chart of a calibration method for a multiphase flow nuclear magnetic resonance flowmeter according to an embodiment of the present invention. The method shown in the figure includes:

[0030] Step S1: sampling the multiphase flow to be measured to obtain a multiphase flow sample.

[0031] The multiphase fluid sample of the well to be measured can be collected on site using a reagent bottle (with the same inner diameter as the inner diameter of the fluid tube of the multiphase flow nuclear magnetic resonance flowmeter).

[0032] Step S2: Using a multiphase flow nuclear magnetic resonance flowmeter, the first amplitude of the free decay signal corresponding to the multiphase flow to be measured and the multiphase flow sample is measured, and based on the first amplitude of the free decay signal, the gas-liquid volume ratio of the multiphase flow to be measured and the hydrogen index of each phase fluid are determined.

[0033] The core of the on-site calibration of the present invention includes the gas-liquid ratio and liquid component content of the multiphase flow being measured. Specifically, the gas-liquid volume ratio and the hydrogen index of each phase of the multiphase flow are determined by measuring the first amplitude of the free decay signal using a multiphase nuclear magnetic resonance flowmeter.

[0034] Step S3, using a multiphase flow nuclear magnetic resonance flowmeter to emit a pulse sequence to the multiphase flow to be measured to measure an attenuation curve, determining a transverse relaxation time based on the attenuation curve, and determining an effective attenuation curve interval and a component content ratio of the multiphase flow to be measured based on the transverse relaxation time.

[0035] By using a multiphase nuclear magnetic resonance flowmeter to transmit a pulse sequence to the multiphase flow under test, the attenuation curve of the multiphase flow under test can be measured, and the transverse relaxation time, or T2 spectrum, can be obtained through inversion. Specifically, taking the multiphase flow under test as crude oil and formation water as an example, the oil and water phases exhibit two spectral peaks on the T2 spectrum. Based on the results of indoor experiments, the two phases can be easily distinguished. The oil peak and water peak curves are integrated to obtain the area enclosed by the horizontal axis, representing the oil content and water content, respectively. The ratio of the oil content to the water content can be used to obtain the ratio of the two components in the multiphase flow under test.

[0036] As an embodiment of the present invention, Figure 2 As shown, the calibration method of the multiphase flow nuclear magnetic resonance flowmeter of the present invention also includes an on-site sampling calibration process, specifically including:

[0037] Step S21 : separating the oil and water in the multiphase flow sample to obtain a single-phase oil sample and a single-phase water sample.

[0038] The multiphase flow to be tested can be separated into oil, gas and water by standing or centrifuging, and the gas in the multiphase flow to be tested is natural gas.

[0039] Step S22 , using a multiphase flow nuclear magnetic resonance flowmeter to detect the pure water, the single-phase oil sample and the single-phase water sample, and obtain the first amplitude values ​​of the magnetization vectors corresponding to the pure water, the single-phase oil sample and the single-phase water sample.

[0040] Among them, a multiphase flow nuclear magnetic resonance flowmeter is used to perform nuclear magnetic resonance on pure water, single-phase oil samples and single-phase water samples, and the first amplitude of the magnetization vector is measured.

[0041] Step S23: determining the hydrogen content index corresponding to the single-phase oil sample and the single-phase water sample according to the first amplitude of the magnetization vector.

[0042] Furthermore, the ratio of the first amplitude of the magnetization vector of the single-phase oil sample and the single-phase water sample to the first amplitude of the magnetization vector of the pure water reagent is the hydrogen index of the oil and water.

[0043] In this embodiment, separating the oil and water in the multiphase flow sample to obtain a single-phase oil sample and a single-phase water sample includes: separating the multiphase flow sample by static or centrifugal technology to obtain a single-phase oil sample and a single-phase water sample.

[0044] In this embodiment, if Figure 3 As shown, using a multiphase flow nuclear magnetic resonance flowmeter to measure the first amplitude of the free decay signal corresponding to the multiphase flow to be measured and the multiphase flow sample, and determining the gas-liquid volume ratio of the multiphase flow to be measured and the hydrogen index of each phase fluid based on the first amplitude of the free decay signal includes:

[0045] Step S31, using a multiphase flow nuclear magnetic resonance flowmeter, measuring the first amplitude of the free decay signal of the multiphase flow sample;

[0046] Step S32: connecting the multiphase flow to be measured to a fluid pipe of a multiphase flow nuclear magnetic resonance flowmeter so that the multiphase flow to be measured flows continuously under a probe of the multiphase flow nuclear magnetic resonance flowmeter, and measuring the first amplitude of a free decay signal of the multiphase flow to be measured using the multiphase flow nuclear magnetic resonance flowmeter;

[0047] Step S33, determining the gas-liquid volume ratio of the multiphase flow to be measured and the hydrogen index of each phase fluid according to the first amplitude value of the free decay signal corresponding to the multiphase flow to be measured and the multiphase flow sample, and the first amplitude value of the magnetization vector of the pure water.

[0048] As an embodiment of the present invention, Figure 4 As shown, the core of the on-site calibration of the present invention also includes determining the pulse frequency, specifically including:

[0049] Step S41, performing temperature control using the temperature control device of the multiphase flow nuclear magnetic resonance flowmeter according to the actual ambient temperature;

[0050] Step S42: After the current temperature reaches the preset operating temperature of the multiphase flow nuclear magnetic resonance flowmeter, the multiphase flow nuclear magnetic resonance flowmeter sends a pulse sequence to the multiphase flow to be measured to obtain a free decay signal curve;

[0051] Step S43: adjusting the pulse frequency of the multiphase flow nuclear magnetic resonance flowmeter by using the free decay signal curve and the magnet frequency of the multiphase flow nuclear magnetic resonance flowmeter at the current temperature.

[0052] As one embodiment of the present invention, the core of the on-site calibration method also includes determining a valid T2 decay curve interval. Specifically, using a multiphase flow nuclear magnetic resonance flowmeter to transmit a pulse sequence to the multiphase flow to be measured to measure the decay curve, and determining the transverse relaxation time based on the decay curve includes: using a multiphase flow nuclear magnetic resonance flowmeter to transmit a pulse sequence to the multiphase flow to be measured to measure the decay curve, and inverting the decay curve to obtain the transverse relaxation time.

[0053] As an embodiment of the present invention, Figure 5 As shown, according to the transverse relaxation time, determining the effective decay curve interval includes:

[0054] Step S51, obtaining the fluid velocity of the multiphase flow to be measured according to the transverse relaxation time;

[0055] Step S52: determining an effective attenuation curve interval on the attenuation curve using the fluid velocity of the multiphase flow to be measured.

[0056] In a specific embodiment of the present invention, Figure 6 As shown, the calibration process of the multiphase flow nuclear magnetic resonance flowmeter in the present invention includes on-site sampling calibration and device calibration process. The device calibration process can be carried out by setting valves on the NMR probe and pipeline of the multiphase flow nuclear magnetic resonance flowmeter. Specifically, Figure 7 The valve layout shown enables rapid on-site calibration of multiphase flow nuclear magnetic resonance flowmeters. The valve layout of this invention applies NMR measurement technology to industrial fields with flowing fluid metering needs, forming a complex fluid flow metering device installed on-site in industrial applications. The multiphase flow nuclear magnetic resonance flowmeter calibration method of this invention can achieve rapid calibration and calibration of oil, gas, and water multiphase flowmeters before actual measurement, preventing flow metering deviations caused by differences in the measured fluid properties. It also achieves true online fluid metering without the need for multiphase separation. During the valve opening and closing measurement process, the original flow manifold of the complex fluid to be measured can maintain normal production activities.

[0057] Specifically, the on-site sampling calibration process includes: using a reagent bottle (with the same inner diameter as the flow meter fluid tube) to collect multiphase fluid samples from the well to be tested, separating them into single-phase oil and water samples, inserting the reagent bottle into the probe antenna, and obtaining the first amplitude of the magnetization vector Amp of the single-phase fluid (formation water, oil) sample. i Among them, the first amplitude value of the magnetization vector and the first amplitude value of the FID curve are the same. At the same time, the reagent bottle is filled with pure water sample and the first amplitude value Amp of pure water is measured. W , by calculating the ratio Amp i / Amp W The hydrogen index HI of oil and water can be obtained respectively o and HI w Liquid phase average hydrogen index HI L :

[0058] HI L =(V O / V L )HI O +(1-V O / V L )HI W

[0059] The device calibration process includes: the core of the on-site calibration of the present invention is to determine the pulse frequency, the gas-liquid ratio of the measured fluid, the liquid phase component content and the effective T2 decay curve range.

[0060] 1) Determine the pulse frequency

[0061] Turn on the temperature control device and set the temperature of the temperature control device according to the actual ambient temperature. Figure 7 As shown, valves #1, #4, and #5 are open, and valves #2 and #3 are closed. The fluid flows through the NMR probe. The FID curve can be used to check whether the results at this time can be used for subsequent NMR measurements. By adjusting the pulse frequency, the fluctuation of the FID curve can be reduced and the signal-to-noise ratio can be improved.

[0062] 2) Measurement of gas-liquid ratio of fluid

[0063] Measure the first amplitude Amp of the FID curve of the fluid flowing through the probe m (The FID signal is a continuously decaying signal, and the maximum amplitude of the signal at the beginning of decay is the first amplitude), and the first amplitude Amp of the liquid sample filled with the fluid tube measured in the laboratory L The hydrogen index HI of each phase fluid and the gas-liquid volume ratio V of the mixed fluid in the instrument can be obtained G / V L Among them, the gas-liquid ratio refers to the volume ratio of natural gas and liquid phase (water + oil), HI m Is the average hydrogen index of the mixed fluid (oil + gas + water), HI Lis the average hydrogen index of the liquid phase.

[0064] HI m =Amp m / Amp w

[0065] HI L =Amp L / Amp w

[0066]

[0067] 3) Liquid phase component content measurement

[0068] Close valves #1, #3, and #5, and open valves #2 and #4 to stop the fluid in the instrument. The production fluid can continue to flow through the bypass line without affecting normal production. The attenuation curve of the fluid in the pipe is measured by emitting a pulse sequence, and the T2 spectrum is obtained by inversion. Taking crude oil and formation water as an example, the oil and water phases show two peaks on the T2 spectrum. The results of indoor experiments make it easy to distinguish the two. Integrate the oil peak and water peak curves to obtain the area S enclosed by the horizontal axis. O and S W , representing the oil content and water content respectively, the content ratio of the two components in the measured liquid can be obtained V O / V W .

[0069]

[0070]

[0071] V O / V W =S O / S W

[0072] 4) Determine the effective T2 decay curve interval

[0073] Open valves #1, #4, and #5, and close valves #2 and #3 to allow fluid to flow through the NMR probe. The NMR probe transmits a pulse sequence to measure the T2 decay curve. Because the attenuation of the fluid within the probe is related to free decay and the velocity of newly inflowing, unpolarized fluid, the slope of the decay curve can be used to derive the fluid velocity. The curve initially exhibits a straight line segment with a constant slope. Select an appropriate straight line segment in the first half of the curve as the valid flow velocity calculation range.

[0074] The present invention applies nuclear magnetic resonance fluid detection technology to industrial measurement sites, performs online, green, non-invasive, full-range detection of complex fluid flow, and realizes on-site calibration of the instrument before use, facilitating accurate detection of multiphase fluid flow.

[0075] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0076] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0077] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0078] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0079] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A calibration method for a multiphase flow nuclear magnetic resonance flowmeter, characterized in that: The method comprises: Sampling the multiphase flow to be measured to obtain a multiphase flow sample; Measuring the first amplitude of the free decay signal corresponding to the multiphase flow to be measured and the multiphase flow sample using a multiphase flow nuclear magnetic resonance flowmeter, and determining the gas-liquid volume ratio of the multiphase flow to be measured and the hydrogen index of each phase fluid based on the first amplitude of the free decay signal; Using a multiphase flow nuclear magnetic resonance flowmeter to emit a pulse sequence to the multiphase flow to be measured to measure an attenuation curve, determining a transverse relaxation time according to the attenuation curve, and determining an effective attenuation curve interval and a component content ratio of the multiphase flow to be measured according to the transverse relaxation time; Wherein, determining the hydrogen content index of each phase fluid according to the first amplitude value of the free decay signal includes: HI o =Amp i油 / Amp w HI w =Amp i水 / Amp w Among them, HI0 represents the hydrogen index of the single-phase oil sample, HI w Indicates the hydrogen index of a single-phase water sample, Amp i油 Represents the first amplitude of the magnetization vector of a single-phase oil sample, Amp i水 Represents the first amplitude of the magnetization vector of a single-phase water sample, Amp W Represents the first magnitude of the magnetization vector of pure water; Wherein, determining the gas-liquid volume ratio of the multiphase flow to be measured according to the first amplitude value of the free decay signal includes: HI m =Amp m / Amp w HI L =Amp L / Amp w Among them, V G / V L Indicates the gas-liquid volume ratio of the multiphase flow to be measured, HI m Indicates the average hydrogen index of the mixed fluid, HI L Indicates the average hydrogen index of the liquid phase, Amp m Indicates the first amplitude of the free decay signal of the multiphase flow to be measured, Amp L Indicates the first amplitude of the free decay signal of the multiphase flow sample, Amp W Represents the first amplitude of the free decay signal of pure water; Wherein, determining the effective attenuation curve interval and the component content ratio of the multiphase flow to be measured according to the transverse relaxation time includes: V O / V W =S O / S W Among them, V O / V W Indicates the component content ratio of the multiphase flow to be measured, S O and S W They respectively represent the area enclosed by the horizontal axis and the area enclosed by the horizontal axis obtained by integrating the oil peak curve, and T2 represents the two spectral peaks of the oil and water phases on the T2 spectrum.

2. The method according to claim 1, characterized in that The method further comprises: Separating the oil and water in the multiphase flow sample to obtain a single-phase oil sample and a single-phase water sample; Using a multiphase flow nuclear magnetic resonance flowmeter to detect pure water, the single-phase oil sample and the single-phase water sample, and obtain the first amplitude of the magnetization vector corresponding to the pure water, the single-phase oil sample and the single-phase water sample; The hydrogen content index corresponding to the single-phase oil sample and the single-phase water sample is determined according to the first amplitude of the magnetization vector.

3. The method according to claim 2, characterized in that The separating of the oil and water in the multiphase flow sample to obtain a single-phase oil sample and a single-phase water sample includes: separating the multiphase flow sample by static method or centrifugal technology to obtain a single-phase oil sample and a single-phase water sample.

4. The method according to claim 2, characterized in that The method of measuring the first amplitude of the free decay signal corresponding to the multiphase flow to be measured and the multiphase flow sample using a multiphase flow nuclear magnetic resonance flowmeter, and determining the gas-liquid volume ratio of the multiphase flow to be measured and the hydrogen index of each phase fluid according to the first amplitude of the free decay signal includes: Using a multiphase flow nuclear magnetic resonance flowmeter, measuring the first amplitude of a free decay signal of the multiphase flow sample; Connecting the multiphase flow to be measured to a fluid pipe of a multiphase flow nuclear magnetic resonance flowmeter so that the multiphase flow to be measured flows continuously under a probe of the multiphase flow nuclear magnetic resonance flowmeter, and measuring the first amplitude of a free decay signal of the multiphase flow to be measured using the multiphase flow nuclear magnetic resonance flowmeter; The gas-liquid volume ratio of the multiphase flow to be measured and the hydrogen index of each phase fluid are determined according to the first amplitude value of the free decay signal corresponding to the multiphase flow to be measured and the multiphase flow sample, and the first amplitude value of the magnetization vector of the pure water.

5. The method according to claim 1, wherein The method further comprises: According to the actual ambient temperature, the temperature is controlled by using the temperature control device of the multiphase flow nuclear magnetic resonance flowmeter; After the current temperature reaches the preset operating temperature of the multiphase flow nuclear magnetic resonance flowmeter, the multiphase flow nuclear magnetic resonance flowmeter sends a pulse sequence to the multiphase flow to be measured to obtain a free decay signal curve; The pulse frequency of the multiphase flow nuclear magnetic resonance flowmeter is adjusted by using the free decay signal curve and the magnet frequency of the multiphase flow nuclear magnetic resonance flowmeter at the current temperature.

6. The method according to claim 1, characterized in that The method of using a multiphase flow nuclear magnetic resonance flowmeter to emit a pulse sequence to the multiphase flow to be measured to measure an attenuation curve, and determining the transverse relaxation time based on the attenuation curve includes: using a multiphase flow nuclear magnetic resonance flowmeter to emit a pulse sequence to the multiphase flow to be measured to measure the attenuation curve, and inverting the attenuation curve to obtain the transverse relaxation time.

7. The method according to claim 1, characterized in that Determining the effective attenuation curve interval according to the transverse relaxation time includes: Obtaining the fluid velocity of the multiphase flow to be measured according to the transverse relaxation time; An effective attenuation curve interval is determined on the attenuation curve using the fluid velocity of the multiphase flow to be measured.

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