Method and device for determining flow velocity metering upper limit of magnetic resonance flowmeter

Abstract

The invention discloses a method and a device for determining a flow velocity metering upper limit of a magnetic resonance flowmeter. The method comprises the following steps: acquiring field intensity distribution data of a plurality of measurement points of the magnetic resonance flowmeter from the starting position of a probe to the center of an antenna, and acquiring the maximum amplitude of an echo signal and the maximum amplitude of noise measured by putting the probe into static pure water; based on the field intensity distribution data and the maximum amplitude of the echo signal, determining a first magnetization vector when the fluid flows to the antenna according to the set flow velocity and the longitudinal relaxation time of the measured fluid; according to the first magnetization vector and the longitudinal relaxation time of the fluid, determining a second magnetization vector attenuating for a set time after the fluid reaches the antenna; whether the difference value between the second magnetization vector and the maximum amplitude of the double noise is smaller than a set difference value or not is judged; if yes, determining the current speed as the upper limit of the flow velocity measurement of the flow meter on the fluid; and if not, modifying the current speed. According to the method, the measurable flow velocity upper limit of the magnetic resonance flowmeter facing different working conditions can be conveniently determined.

Description

Technical Field

[0001] This invention relates to the fields of online metering of multiphase flow of oil and gas and low-field magnetic resonance application technology, and particularly to a method and device for determining the upper limit of flow velocity measurement of a magnetic resonance flowmeter. Background Technology

[0002] Magnetic resonance multiphase flow meters can be installed at the wellhead of oil and gas production wells to measure the flow rate of the three-phase mixture of oil, gas, and water produced from downhole to the surface process in real time. Compared with other multiphase flow metering technologies, its advantages include no need for phase separation, non-invasive sensors, environmental friendliness, high efficiency, and accuracy.

[0003] To meet the measurement range requirements (different oil and gas wells have different production, water cut, and oil-gas ratio fluctuation ranges) and due to installation space limitations (such as installation in metering rooms, offshore platforms, and deep water installation), the demand for metering equipment varies. Therefore, it is necessary to design and apply devices with different measurement ranges for different oil well parameters.

[0004] The magnetic resonance multiphase flow measurement method consists of two stages: the magnetization stage and the echo acquisition stage. The magnetization stage requires magnetizing the fluid under test to a certain magnetization vector. Then, in the echo acquisition stage, different pulse sequences are applied to obtain the required fluid signal, and the flow velocity and phase content information of the multiphase flow under test are obtained through corresponding mathematical equations.

[0005] For flow velocity measurement, the magnetization vector acquired by fluid entering the antenna region of a magnetic resonance multiphase flowmeter probe is related to the magnet structure and the flow velocity. Magnetic resonance multiphase flowmeters come in different models to meet various measurement needs, each with different magnet structures and magnetic field distributions. Current technology still uses a uniform flow velocity upper limit for the same model of equipment. However, even with identical magnet structures, slight differences in installation processes and magnetization intensity can result in slightly different magnetic field strengths. Therefore, it is necessary to test the magnetic field distribution of each magnetic resonance multiphase flowmeter before it leaves the factory and simultaneously calculate the upper limit for flow velocity measurement for that device. Summary of the Invention

[0006] To enrich process routes and increase the range of options, this invention provides a method and apparatus for determining the upper limit of flow velocity measurement of a magnetic resonance flowmeter, which can conveniently determine the upper limit of measurable flow velocity of the magnetic resonance flowmeter under different operating conditions.

[0007] In a first aspect, embodiments of the present invention provide a method for determining the upper limit of flow velocity measurement of a magnetic resonance flowmeter, comprising:

[0008] The data acquisition steps include acquiring the field strength at multiple measurement points from the probe start position to the antenna center of the magnetic resonance flowmeter, obtaining field strength distribution data, and acquiring the maximum amplitude value of the magnetic resonance echo signal and the maximum amplitude value of the noise obtained by immersing the probe of the magnetic resonance flowmeter in static pure water.

[0009] The step of determining the magnetization vector of the fluid flowing through the antenna involves determining the first magnetization vector of the fluid when it reaches the antenna of the magnetic resonance flowmeter, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, according to the set flow velocity and the longitudinal relaxation time of the fluid being measured.

[0010] The attenuation magnetization vector determination step involves determining the second magnetization vector after the measured fluid reaches the antenna and attenuates for a set time, based on the determined first magnetization vector and the longitudinal relaxation time of the measured fluid.

[0011] Determine whether the difference between the determined second magnetization vector and twice the maximum amplitude of the noise is less than a set difference;

[0012] If so, the current velocity is determined as the upper limit of the flow rate measurement of the fluid being measured by the resonant flow meter;

[0013] If not, modify the current speed and return to the step of determining the magnetization vector of the fluid flowing through the antenna.

[0014] In some embodiments, if the fluid being measured is a single-phase fluid, determining the first magnetization vector of the fluid as it flows to the antenna of the magnetic resonance flowmeter, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, and according to a set flow velocity and the longitudinal relaxation time of the fluid being measured, includes:

[0015] Based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, and according to the set flow velocity and the longitudinal relaxation time of the fluid being measured, the first magnetization vector of the fluid being measured when it reaches the antenna of the magnetic resonance flowmeter is determined by the following equations (1) and (2):

[0016]

[0017]

[0018] In equations (1) and (2), M is the first magnetization vector, F is the field strength, and the subscript t represents time, corresponding to a measurement point; M_signal is the maximum amplitude of the magnetic resonance echo signal; t s t is the time interval between two adjacent measurement points for the fluid being measured. s = s / v, where s is the distance between two adjacent measurement points, v is the flow velocity of the fluid being measured, and T1 is the longitudinal relaxation time of the fluid being measured.

[0019] In some embodiments, determining a second magnetization vector, based on a determined first magnetization vector and the longitudinal relaxation time of the fluid under test, after the fluid under test has decayed for a set time upon reaching the antenna, includes:

[0020] Based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test, the second magnetization vector, which decays for a set time after the fluid under test reaches the antenna, is determined by the following formula (3):

[0021]

[0022] In equation (3), M(T_velocity) is the second magnetization vector that decays for a set time T_velocity after the measured fluid reaches the antenna. 天线 The first magnetization vector is the fluid being measured flowing to the antenna of the magnetic resonance flowmeter.

[0023] In some embodiments, if the fluid being measured contains oil and water, determining the first magnetization vector of the fluid as it flows to the antenna of the magnetic resonance flowmeter, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, and according to a set flow velocity and the longitudinal relaxation time of the fluid being measured, includes:

[0024] Assuming the fluid being measured contains only oil, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, according to the set flow rate and the longitudinal relaxation time of the oil contained in the fluid being measured, the third magnetization vector when the fluid being measured flows to the antenna of the magnetic resonance flowmeter is determined by the above equations (1) and (2).

[0025] Assuming the fluid being measured contains only water, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, according to the set flow rate and the longitudinal relaxation time of the water contained in the fluid being measured, the fourth magnetization vector when the fluid being measured flows to the antenna of the magnetic resonance flowmeter is determined by the above equations (1) and (2).

[0026] Based on the determined third and fourth magnetization vectors and the water content of the fluid being measured, the first magnetization vector when the fluid reaches the antenna of the magnetic resonance flowmeter is determined by the following formula (4):

[0027]

[0028] In equation (4), M' 天线 This is the first magnetization vector when the non-single-phase measured fluid flows to the antenna of the magnetic resonance flowmeter. M represents the water content of the fluid being measured. 天线,油 M is the third magnetization vector as it flows to the antenna of the magnetic resonance flowmeter, assuming the measured fluid contains only oil. 天线,水 This is the fourth magnetization vector as the fluid being measured flows to the antenna of the magnetic resonance flowmeter, assuming it contains only water.

[0029] In some embodiments, if the fluid under test does not contain gas, determining the second magnetization vector, based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test, after the fluid under test has decayed for a set time upon reaching the antenna, includes:

[0030] Based on the determined first magnetization vector and the longitudinal relaxation time of the oil and water contained in the measured fluid, the second magnetization vector after the measured fluid reaches the antenna and decays for a set time is determined by the following formula (5):

[0031]

[0032] In equation (5), M′(T_velocity) is the second magnetization vector of the measured fluid containing oil and water, which decays to a set time T_velocity after reaching the antenna, and T2 is the average longitudinal relaxation time of the oil and water contained in the measured fluid.

[0033] In some embodiments, if the fluid under test contains oil, gas, and water, determining the second magnetization vector, based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test, after the fluid under test has decayed for a set time upon reaching the antenna, includes:

[0034] Based on the determined first magnetization vector, the gas-liquid ratio of the measured fluid, and the longitudinal relaxation time of the oil and water contained therein, the second magnetization vector after the measured fluid reaches the antenna and decays for a set time is determined by the following formula (6):

[0035]

[0036] In equation (6), M″(T_velocity) is the second magnetization vector of the measured fluid containing oil, gas and water, which decays to a set time T_velocity after reaching the antenna, T2 is the average longitudinal relaxation time of the oil and water contained in the measured fluid, and G is the gas-liquid ratio of the measured fluid.

[0037] In some embodiments, the set time is 50 microseconds.

[0038] Secondly, embodiments of the present invention provide a device for determining the upper limit of flow velocity measurement of a magnetic resonance flowmeter, comprising:

[0039] The data acquisition module is used to acquire the field strength of multiple measurement points from the probe start position to the antenna center of the magnetic resonance flowmeter, obtain field strength distribution data, and acquire the maximum amplitude value of the magnetic resonance echo signal and the maximum amplitude value of the noise obtained by immersing the probe of the magnetic resonance flowmeter in static pure water.

[0040] The magnetization vector determination module for fluid flowing through the antenna is used to determine the first magnetization vector of the fluid flowing to the antenna of the magnetic resonance flowmeter based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, according to the set flow velocity and the longitudinal relaxation time of the fluid being measured.

[0041] The attenuation magnetization vector determination module is used to determine the second magnetization vector of the fluid under test after it has been attenuated for a set time after reaching the antenna, based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test.

[0042] The judgment module is used to determine whether the difference between the determined second magnetization vector and twice the maximum amplitude of the noise is less than a set difference.

[0043] The flow rate measurement upper limit determination module is used to determine the current velocity as the upper limit of the flow rate measurement of the fluid being measured by the resonant flow meter when the judgment module determines that it is true.

[0044] The speed modification module is used to modify the current speed when the judgment module determines that the error is not true.

[0045] Thirdly, embodiments of the present invention provide a computer storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method for determining the upper limit of flow rate measurement of a magnetic resonance flowmeter.

[0046] Fourthly, this disclosure provides a server, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-described method for determining the upper limit of flow rate measurement of a magnetic resonance flowmeter.

[0047] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0048] (1) The method for determining the upper limit of flow velocity measurement of a magnetic resonance flowmeter provided in this embodiment of the invention detects the field strength distribution of the magnetic resonance flowmeter and calculates the magnetization vector of the fluid flowing into the detection antenna with different longitudinal relaxation times based on the field strength distribution. Then, the magnetization vector attenuates for a set time after reaching the antenna. Using twice the maximum noise amplitude measured by immersing the probe of the magnetic resonance flowmeter in static pure water as a constraint, the velocity is iteratively corrected to obtain the upper limit of the velocity that meets the constraint, which is then used as the upper limit of flow velocity measurement for the resonant flowmeter. This method can conveniently determine the upper limit of measurable flow velocity of a magnetic resonance flowmeter under different operating conditions, providing guidance for the design of magnetic resonance flowmeters and even their selection in field applications.

[0049] (2) The method for determining the upper limit of flow rate measurement of magnetic resonance flowmeter provided in this embodiment of the invention is not only applicable to single-phase fluids, but can also determine the upper limit of flow rate measurement of multiphase fluids by magnetic resonance flowmeter based on the longitudinal relaxation time and water content of oil and water contained in the fluid.

[0050] (3) The method for determining the upper limit of flow velocity measurement of the magnetic resonance flowmeter provided in this embodiment of the invention is not only applicable to single-phase fluids, but can also determine the upper limit of flow velocity measurement of the magnetic resonance flowmeter for multiphase fluids based on the longitudinal relaxation time, water cut, and gas-liquid ratio of the oil and water contained in the fluid, so as to provide different upper limits of flow velocity when the magnetic resonance flowmeter is applied to different oil and gas wells.

[0051] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0052] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0053] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0054] Figure 1 This is a flowchart of the method for determining the upper limit of flow velocity measurement of the magnetic resonance flowmeter in Embodiment 1 of the present invention;

[0055] Figure 2 This is a curve showing the change in magnetization vector of the tested oil and water samples as they flow into the antenna region under the magnetic field distribution and rated flow rate in Embodiment 1 of the present invention.

[0056] Figure 3 This is a flowchart of the method for determining the upper limit of flow velocity measurement of the magnetic resonance flowmeter in Embodiment 2 of the present invention;

[0057] Figure 4 To determine the upper limit of flow velocity in the oil-water two-phase flow velocity measurement echo attenuation curve in Embodiment 2 of the present invention;

[0058] Figure 5 This is a flowchart of the method for determining the upper limit of flow velocity measurement of the magnetic resonance flowmeter in Embodiment 3 of the present invention;

[0059] Figure 6 To determine the upper limit of flow velocity in the three-phase flow velocity measurement echo attenuation curve of oil, gas and water in Embodiment 3 of the present invention;

[0060] Figure 7This is a schematic diagram of the device for determining the upper limit of flow velocity measurement of a magnetic resonance flowmeter in an embodiment of the present invention. Detailed Implementation

[0061] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0062] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0063] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0064] This invention provides a method and apparatus for determining the upper limit of flow velocity measurement of a magnetic resonance flow meter, which can conveniently determine the upper limit of measurable flow velocity of the magnetic resonance flow meter under different operating conditions.

[0065] Example 1

[0066] Embodiment 1 of the present invention provides a method for determining the upper limit of flow velocity measurement of a magnetic resonance flowmeter. Taking a single-phase fluid as an example, the process is as follows: Figure 1 As shown, it includes the following steps:

[0067] Step S11: Data acquisition step, acquire the field strength of multiple measurement points from the probe start position to the antenna center of the magnetic resonance flowmeter, obtain field strength distribution data, and acquire the maximum amplitude value of the magnetic resonance echo signal and the maximum amplitude value of the noise obtained by immersing the probe of the magnetic resonance flowmeter in static pure water.

[0068] The magnetic field strength in the central region of the magnet in the probe of a magnetic resonance flowmeter is measured using field strength measuring instruments such as a gaussmeter or fluxgate magnetometer. Taking gaussmeter measurement as an example, the gaussmeter probe records the magnetic field strength starting from the point of entry into the magnetic resonance flowmeter probe. The interval between each measurement point is fixed at s, and the field strength and gaussmeter probe displacement data are recorded to obtain the correlation curve between magnetic field distribution and displacement. A magnetic field distribution diagram is then plotted, as shown below. Figure 2 As shown in the image above.

[0069] To perform indoor calibration of the equipment, the probe of the magnetic resonance flowmeter is immersed in a pure water sample, and both sides of the fluid tube are sealed. At this time, the maximum amplitude of the magnetic resonance echo signal M_signal and the maximum amplitude of the noise M_noise of the static water sample are measured.

[0070] Step S12: Determining the magnetization vector of the fluid flowing through the antenna. Based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, and according to the set flow velocity and the longitudinal relaxation time of the fluid being measured, the first magnetization vector of the fluid being measured when it flows to the antenna of the magnetic resonance flowmeter is determined.

[0071] During the flow measurement phase, the fluid begins to magnetize as soon as it flows into the probe. When evaluating the magnetization vector of the fluid as it flows through the magnet and reaches the antenna region, two factors must be considered simultaneously: the flow velocity v and the longitudinal relaxation time T1 of the fluid.

[0072] Specifically, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, and according to the set flow velocity and the longitudinal relaxation time of the fluid being measured, the first magnetization vector of the fluid being measured when it reaches the antenna of the magnetic resonance flowmeter is determined by the following equations (1) and (2):

[0073]

[0074] In equations (1) and (2), M is the first magnetization vector, F is the field strength, and the subscript t represents time, corresponding to a measurement point; M_signal is the maximum amplitude of the magnetic resonance echo signal; t s t is the time interval between two adjacent measurement points for the fluid being measured. s = s / v, where s is the distance between two adjacent measurement points, v is the flow velocity of the fluid being measured, and T1 is the longitudinal relaxation time of the fluid being measured.

[0075] The magnetization vector at the time corresponding to the monitoring point being the center position of the antenna is determined as the first magnetization vector when the measured fluid flows to the antenna of the magnetic resonance flowmeter.

[0076] When the fluid being measured is a single-component fluid, the above formula can directly yield the magnetization vector when the fluid reaches the antenna, such as... Figure 2 In the lower part of the image, M_water and M_oil are... Figure 2The lower figure shows the curve of magnetization vector change with displacement when the measured fluid is a single-phase fluid such as water or oil.

[0077] Step S13: Attenuation magnetization vector determination step. Based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test, determine the second magnetization vector after the fluid under test has been attenuated for a set time after reaching the antenna.

[0078] Based on the first magnetization vector determined in step S12 and the longitudinal relaxation time of the fluid under test, the second magnetization vector after the fluid under test reaches the antenna and decays for a set time is determined by the following formula (3):

[0079]

[0080] In equation (3), M(T_velocity) is the second magnetization vector that decays for a set time T_velocity after the measured fluid reaches the antenna. 天线 The first magnetization vector is the fluid being measured flowing to the antenna of the magnetic resonance flowmeter.

[0081] T_velocity is typically set to 50 microseconds. This is based on two considerations: firstly, a longer time would result in a lower sampling frequency; secondly, for water and oil attenuation signals, the attenuation linearity is usually good and the slope is relatively large within 50ms, with the attenuation mainly coming from the contribution of flow velocity. However, the subsequent echo train itself exhibits an increasing proportion of exponential attenuation, resulting in poor linearity.

[0082] Step S14: Determine whether the difference between the determined second magnetization vector and twice the maximum noise amplitude is less than the set difference.

[0083] As the velocity increases, the second magnetization vector, which decays for a set time after reaching the antenna, gradually decreases. This results in a low signal-to-noise ratio (SNR), causing some of the signal to be submerged by noise and leading to data distortion. Therefore, the velocity at which the difference between the second magnetization vector and twice the maximum noise amplitude is less than the set interpolation value is determined as the upper limit for the flow velocity measurement of the fluid by the resonant flowmeter.

[0084] If step S14 is incorrect, proceed to step S15; if step S14 is correct, proceed to step S16.

[0085] Step S15: Modify the current speed.

[0086] After step S15, return to step S12.

[0087] Step S16: Determine the current velocity as the upper limit of the flow rate measurement of the fluid being measured by the resonant flow meter.

[0088] The method for determining the upper limit of flow velocity measurement for a magnetic resonance flowmeter provided in Embodiment 1 of this invention involves detecting the field strength distribution of the magnetic resonance flowmeter and calculating the magnetization vector of fluid flowing into the detection antenna at different longitudinal relaxation times based on the field strength distribution. This yields the magnetization vector that decays after a set time upon reaching the antenna. Using twice the maximum noise amplitude measured when the magnetic resonance flowmeter probe is immersed in static pure water as a constraint, the velocity is iteratively corrected to obtain the upper limit of the velocity that meets the constraint, which serves as the upper limit of flow velocity measurement for the resonant flowmeter. This method can conveniently determine the upper limit of measurable flow velocity for a magnetic resonance flowmeter under different operating conditions, providing guidance for the design of magnetic resonance flowmeters and even their selection in field applications.

[0089] Example 2

[0090] Embodiment 2 of the present invention provides a method for determining the upper limit of flow velocity measurement of a magnetic resonance flowmeter. Taking the measured fluid as an oil-water two-phase fluid as an example, the process is as follows: Figure 3 As shown, it includes the following steps:

[0091] Step S31: Obtain the field strength at multiple measurement points from the probe start position to the antenna center of the magnetic resonance flowmeter, obtain the field strength distribution data, and obtain the maximum amplitude of the magnetic resonance echo signal and the maximum amplitude of the noise obtained by immersing the probe of the magnetic resonance flowmeter in static pure water.

[0092] Step S32: Based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, determine the first magnetization vector of the fluid being measured when it flows to the antenna of the magnetic resonance flowmeter, according to the set flow velocity, the longitudinal relaxation time of the fluid being measured containing oil and water, and the water content.

[0093] Assuming the fluid being measured contains only oil, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, and according to the set flow rate and the longitudinal relaxation time of the oil contained in the fluid being measured, the third magnetization vector when the fluid being measured flows to the antenna of the magnetic resonance flowmeter is determined by the above equations (1) and (2).

[0094] Assuming the fluid being measured contains only water, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, and according to the set flow rate and the longitudinal relaxation time of the water contained in the fluid being measured, the fourth magnetization vector of the fluid being measured when it flows to the antenna of the magnetic resonance flowmeter is determined by the above equations (1) and (2).

[0095] Based on the determined third and fourth magnetization vectors and the water content of the fluid being measured, the first magnetization vector when the fluid reaches the antenna of the magnetic resonance flowmeter is determined by the following formula (4):

[0096]

[0097] In equation (4), M' 天线This is the first magnetization vector when the non-single-phase measured fluid flows to the antenna of the magnetic resonance flowmeter. M represents the water content of the fluid being measured. 天线,油 M is the third magnetization vector as it flows to the antenna of the magnetic resonance flowmeter, assuming the measured fluid contains only oil. 天线,水 This is the fourth magnetization vector as the fluid being measured flows to the antenna of the magnetic resonance flowmeter, assuming it contains only water.

[0098] Step S33: Based on the determined first magnetization vector and the longitudinal relaxation time of the fluid being measured (containing oil and water), determine the second magnetization vector that decays for a set time after the fluid reaches the antenna.

[0099] Based on the determined first magnetization vector and the longitudinal relaxation time of the oil and water contained in the measured fluid, the second magnetization vector after the measured fluid reaches the antenna and decays for a set time is determined by the following formula (5):

[0100]

[0101] In equation (5), M′(T_velocity) is the second magnetization vector of the measured fluid containing oil and water, which is attenuated for a set time T_velocity after reaching the antenna; T2 is the average longitudinal relaxation time of the oil and water contained in the measured fluid. The average value here can be a simple arithmetic average or a content-weighted average.

[0102] Step S34: Determine whether the difference between the determined second magnetization vector and twice the maximum noise amplitude is less than the set difference.

[0103] If step S34 is incorrect, proceed to step S35; if step S34 is correct, proceed to step S36.

[0104] Step S35: Modify the current speed.

[0105] After step S35, return to step S32.

[0106] Step S36: Determine the current velocity as the upper limit of the flow rate measurement of the fluid being measured by the resonant flow meter.

[0107] See Figure 4 As shown, this is the template for the upper limit of the oil-water two-phase fluid velocity. The maximum velocity is found when the magnetization vector M'(T_velocity) at time T_velocity is close to twice M_noise.

[0108] The method for determining the upper limit of flow rate measurement of a magnetic resonance flowmeter provided in Embodiment 2 of the present invention is applicable to multiphase fluids containing oil and water. The upper limit of flow rate measurement of the magnetic resonance flowmeter for multiphase fluids is determined based on the longitudinal relaxation time and water content of the oil and water contained in the fluid.

[0109] Example 3

[0110] Embodiment 3 of the present invention provides a method for determining the upper limit of flow velocity measurement of a magnetic resonance flowmeter. Taking the measured fluid as a three-phase fluid of oil, gas, and water as an example, the process is as follows: Figure 5 As shown, it includes the following steps:

[0111] Step S51: Obtain the field strength at multiple measurement points from the probe start position to the antenna center of the magnetic resonance flowmeter, obtain the field strength distribution data, and obtain the maximum amplitude of the magnetic resonance echo signal and the maximum amplitude of the noise obtained by immersing the probe of the magnetic resonance flowmeter in static pure water.

[0112] Step S52: Based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, determine the first magnetization vector of the fluid being measured when it flows to the antenna of the magnetic resonance flowmeter, according to the set flow velocity, the longitudinal relaxation time of the fluid being measured containing oil and water, and the water content.

[0113] Step S53: Based on the determined first magnetization vector, the gas-liquid ratio of the fluid being measured, and the longitudinal relaxation time containing oil and water, determine the second magnetization vector that decays for a set time after the fluid being measured reaches the antenna.

[0114] Based on the determined first magnetization vector and the gas-liquid ratio of the fluid under test, as well as the longitudinal relaxation time of the oil and water contained therein, the second magnetization vector after the fluid under test reaches the antenna and attenuates for a set time is determined by the following formula (6):

[0115]

[0116] In equation (6), M″(T_velocity) is the second magnetization vector of the measured fluid containing oil, gas and water, which decays to a set time T_velocity after reaching the antenna, T2 is the average longitudinal relaxation time of the oil and water contained in the measured fluid, and G is the gas-liquid ratio of the measured fluid.

[0117] Step S54: Determine whether the difference between the determined second magnetization vector and twice the maximum noise amplitude is less than the set difference.

[0118] If step S54 determines no, proceed to step S55; if step S54 determines yes, proceed to step S56.

[0119] Step S55: Modify the current speed.

[0120] After step S55, return to step S52.

[0121] Step S56: Determine the current velocity as the upper limit of the flow rate measurement of the fluid being measured by the resonant flow meter.

[0122] See Figure 6 As shown, this is the template for the upper limit of the velocity of the three-phase fluid of oil, gas and water. The maximum velocity is found when the magnetization vector M″(T_velocity) at time T_velocity is close to twice M_noise.

[0123] The method for determining the upper limit of flow velocity measurement of a magnetic resonance flowmeter provided in Embodiment 3 of the present invention is applicable to multiphase fluids containing oil, gas and water. It can determine the upper limit of flow velocity measurement of the magnetic resonance flowmeter for multiphase fluids based on the longitudinal relaxation time, water cut and gas-liquid ratio of the oil and water contained in the fluid, so as to provide different upper limits of flow velocity when the magnetic resonance flowmeter is applied to different oil and gas wells.

[0124] The steps in Examples 2 and 3 that are consistent with those in Example 1 can be found in the description in Example 1. The steps in Example 3 that are consistent with those in Example 2 can be found in the description in Example 2.

[0125] Based on the inventive concept of this invention, embodiments of this invention also provide a device for determining the upper limit of flow velocity measurement in a magnetic resonance flowmeter, the structure of which is as follows: Figure 7 As shown, it includes:

[0126] The data acquisition module 71 is used to acquire the field strength of multiple measurement points from the probe start position to the antenna center of the magnetic resonance flowmeter, obtain field strength distribution data, and acquire the maximum amplitude value of the magnetic resonance echo signal and the maximum amplitude value of the noise obtained by immersing the probe of the magnetic resonance flowmeter in static pure water.

[0127] The magnetization vector determination module 72 for fluid flowing through the antenna is used to determine the first magnetization vector of the fluid when it flows to the antenna of the magnetic resonance flowmeter, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, according to the set flow velocity and the longitudinal relaxation time of the fluid being measured.

[0128] The attenuated magnetization vector determination module 73 is used to determine the second magnetization vector of the fluid under test after it has been attenuated for a set time after reaching the antenna, based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test.

[0129] The judgment module 74 is used to determine whether the difference between the determined second magnetization vector and twice the maximum noise amplitude is less than a set difference.

[0130] The flow rate measurement upper limit determination module 75 is used to determine the current speed as the flow rate measurement upper limit of the resonant flow meter for the measured fluid when the judgment module 74 determines that it is true.

[0131] The speed modification module 76 is used to modify the current speed when the judgment module 74 determines otherwise.

[0132] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0133] Based on the inventive concept of the present invention, embodiments of the present invention also provide a computer storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-mentioned method for determining the upper limit of flow rate measurement of a magnetic resonance flowmeter.

[0134] Based on the inventive concept of the present invention, embodiments of the present invention also provide a server, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-mentioned method for determining the upper limit of flow rate measurement of the magnetic resonance flowmeter.

[0135] Unless otherwise specifically stated, terms such as processing, calculation, operation, determination, display, etc., may refer to the actions and / or processes of one or more processing or computing systems or similar devices that represent the manipulation and conversion of data representing physical (e.g., electronic) quantities within the registers or memory of the processing system into other data similarly representing physical quantities within the memory, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals can be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0136] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0137] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than those stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features in a single disclosed embodiment. Therefore, the appended claims are hereby clearly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0138] Those skilled in the art will also understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments herein can be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate the interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps described above are generally described in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those skilled in the art can implement the described functionality in alternative ways for each specific application; however, such implementation decisions should not be construed as departing from the scope of this disclosure.

[0139] The steps of the methods or algorithms described in conjunction with the embodiments herein can be directly embodied in hardware, software modules executed by a processor, or a combination thereof. The software modules can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. Alternatively, the processor and storage medium can exist as discrete components in the user terminal.

[0140] For software implementation, the techniques described in this application can be implemented using modules (e.g., procedures, functions, etc.) that perform the functions described in this application. This software code can be stored in memory units and executed by a processor. The memory units can be implemented within the processor or outside the processor; in the latter case, they are communicatively coupled to the processor via various means, as is well known in the art.

[0141] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term “comprising” as used in the specification or claims is interpreted in a manner similar to the term “including,” as it is understood when used as a conjunction in the claims. Additionally, the use of any term “or” in the specification of the claims is intended to mean “non-exclusive or.” The terms “first,” “second,” etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

Claims

1. A method for determining the upper limit of flow velocity measurement in a magnetic resonance flowmeter, characterized in that, include: The data acquisition steps include acquiring the field strength at multiple measurement points from the probe start position to the antenna center of the magnetic resonance flowmeter, obtaining field strength distribution data, and acquiring the maximum amplitude value of the magnetic resonance echo signal and the maximum amplitude value of the noise obtained by immersing the probe of the magnetic resonance flowmeter in static pure water. The step of determining the magnetization vector of the fluid flowing through the antenna involves determining the first magnetization vector of the fluid when it reaches the antenna of the magnetic resonance flowmeter, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, according to the set flow velocity and the longitudinal relaxation time of the fluid being measured. The attenuation magnetization vector determination step involves determining the second magnetization vector after the measured fluid reaches the antenna and attenuates for a set time, based on the determined first magnetization vector and the longitudinal relaxation time of the measured fluid. Determine whether the difference between the determined second magnetization vector and twice the maximum amplitude of the noise is less than a set difference; If so, the current velocity is determined as the upper limit of the flow rate measurement of the fluid being measured by the resonant flow meter; If not, modify the current speed and return to the step of determining the magnetization vector of the fluid flowing through the antenna.

2. The method as described in claim 1, characterized in that, If the fluid being measured is a single-phase fluid, the determination of the first magnetization vector of the fluid as it flows to the antenna of the magnetic resonance flowmeter, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, and according to the set flow velocity and the longitudinal relaxation time of the fluid being measured, includes: Based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, and according to the set flow velocity and the longitudinal relaxation time of the fluid being measured, the first magnetization vector of the fluid being measured when it reaches the antenna of the magnetic resonance flowmeter is determined by the following equations (1) and (2): In equations (1) and (2), M is the first magnetization vector, F is the field strength, and the subscript t represents time, corresponding to a measurement point; M_signal is the maximum amplitude of the magnetic resonance echo signal; t s t is the time interval between two adjacent measurement points for the fluid being measured. s = s / v, where s is the distance between two adjacent measurement points, v is the flow velocity of the fluid being measured, and T1 is the longitudinal relaxation time of the fluid being measured.

3. The method as described in claim 2, characterized in that, The step of determining the second magnetization vector, based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test, after the fluid under test has decayed for a set time upon reaching the antenna, includes: Based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test, the second magnetization vector, which decays for a set time after the fluid under test reaches the antenna, is determined by the following formula (3): In equation (3), M(T_velocity) is the second magnetization vector that decays for a set time T_velocity after the measured fluid reaches the antenna. 天线 The first magnetization vector is the fluid being measured flowing to the antenna of the magnetic resonance flowmeter.

4. The method as described in claim 2, characterized in that, If the fluid being measured contains oil and water, the determination of the first magnetization vector of the fluid as it flows to the antenna of the magnetic resonance flowmeter, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, and according to the set flow velocity and the longitudinal relaxation time of the fluid being measured, includes: Assuming the fluid being measured contains only oil, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, according to the set flow rate and the longitudinal relaxation time of the oil contained in the fluid being measured, the third magnetization vector when the fluid being measured flows to the antenna of the magnetic resonance flowmeter is determined by the above equations (1) and (2). Assuming the fluid being measured contains only water, based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, according to the set flow rate and the longitudinal relaxation time of the water contained in the fluid being measured, the fourth magnetization vector when the fluid being measured flows to the antenna of the magnetic resonance flowmeter is determined by the above equations (1) and (2). Based on the determined third and fourth magnetization vectors and the water content of the fluid being measured, the first magnetization vector when the fluid reaches the antenna of the magnetic resonance flowmeter is determined by the following formula (4): In equation (4), M' 天线 This is the first magnetization vector when the non-single-phase measured fluid flows to the antenna of the magnetic resonance flowmeter. M represents the water content of the fluid being measured. 天线,油 Assuming the measured fluid contains only oil, the third magnetization vector as it flows to the antenna of the magnetic resonance flowmeter is M. 天线,水 This is the fourth magnetization vector as the fluid being measured flows to the antenna of the magnetic resonance flowmeter, assuming it contains only water.

5. The method as described in claim 4, characterized in that, If the fluid under test does not contain gas, determining the second magnetization vector, based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test, after the fluid under test has decayed for a set time upon reaching the antenna, includes: Based on the determined first magnetization vector and the longitudinal relaxation time of the oil and water contained in the measured fluid, the second magnetization vector after the measured fluid reaches the antenna and decays for a set time is determined by the following formula (5): In equation (5), M′(T_velocity) is the second magnetization vector of the measured fluid containing oil and water, which decays to a set time T_velocity after reaching the antenna, and T2 is the average longitudinal relaxation time of the oil and water contained in the measured fluid.

6. The method as described in claim 4, characterized in that, If the fluid under test contains oil, gas, and water, determining the second magnetization vector, based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test, after the fluid under test has decayed for a set time upon reaching the antenna, includes: Based on the determined first magnetization vector, the gas-liquid ratio of the fluid being measured, and the longitudinal relaxation time of the oil and water contained therein, the second magnetization vector after the measured fluid reaches the antenna and decays for a set time is determined by the following formula (6): In equation (6), M′′(T_velocity) is the second magnetization vector of the measured fluid containing oil, gas and water, which decays to a set time T_velocity after reaching the antenna, T2 is the average longitudinal relaxation time of the oil and water contained in the measured fluid, and G is the gas-liquid ratio of the measured fluid.

7. The method according to any one of claims 1 to 6, characterized in that, The set time is 50 microseconds.

8. A device for determining the upper limit of flow velocity measurement in a magnetic resonance flowmeter, characterized in that, include: The data acquisition module is used to acquire the field strength of multiple measurement points from the probe start position to the antenna center of the magnetic resonance flowmeter, obtain field strength distribution data, and acquire the maximum amplitude value of the magnetic resonance echo signal and the maximum amplitude value of the noise obtained by immersing the probe of the magnetic resonance flowmeter in static pure water. The magnetization vector determination module for fluid flowing through the antenna is used to determine the first magnetization vector of the fluid flowing to the antenna of the magnetic resonance flowmeter based on the field strength distribution data and the maximum amplitude of the magnetic resonance echo signal, according to the set flow velocity and the longitudinal relaxation time of the fluid being measured. The attenuation magnetization vector determination module is used to determine the second magnetization vector of the fluid under test after it has been attenuated for a set time after reaching the antenna, based on the determined first magnetization vector and the longitudinal relaxation time of the fluid under test. The judgment module is used to determine whether the difference between the determined second magnetization vector and twice the maximum amplitude of the noise is less than a set difference. The flow rate measurement upper limit determination module is used to determine the current velocity as the upper limit of the flow rate measurement of the fluid being measured by the resonant flow meter when the judgment module determines that it is true. The speed modification module is used to modify the current speed when the judgment module determines that the error is not true.

9. A computer storage medium, characterized in that, The computer storage medium stores computer-executable instructions, which, when executed by a processor, implement the method for determining the upper limit of flow velocity measurement of the magnetic resonance flowmeter as described in any one of claims 1 to 7.

10. A server, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method for determining the upper limit of flow velocity measurement of the magnetic resonance flowmeter according to any one of claims 1 to 7.

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