CN108254588B - Method and device for measuring flow velocity of fluid by nuclear magnetic resonance - Google Patents
Method and device for measuring flow velocity of fluid by nuclear magnetic resonance Download PDFInfo
- Publication number
- CN108254588B CN108254588B CN201810025634.0A CN201810025634A CN108254588B CN 108254588 B CN108254588 B CN 108254588B CN 201810025634 A CN201810025634 A CN 201810025634A CN 108254588 B CN108254588 B CN 108254588B
- Authority
- CN
- China
- Prior art keywords
- fluid sample
- fluid
- magnetic field
- magnet
- magnet section
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000012530 fluid Substances 0.000 title claims abstract description 332
- 238000005481 NMR spectroscopy Methods 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 title claims abstract description 53
- 238000012545 processing Methods 0.000 claims abstract description 60
- 230000010287 polarization Effects 0.000 claims abstract description 51
- 238000005259 measurement Methods 0.000 claims abstract description 43
- 230000009471 action Effects 0.000 claims abstract description 20
- 238000002592 echocardiography Methods 0.000 claims description 46
- 230000005415 magnetization Effects 0.000 claims description 19
- 238000001208 nuclear magnetic resonance pulse sequence Methods 0.000 claims description 16
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 3
- 230000001419 dependent effect Effects 0.000 claims description 3
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 claims description 3
- 238000000685 Carr-Purcell-Meiboom-Gill pulse sequence Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 230000008569 process Effects 0.000 description 6
- 238000004364 calculation method Methods 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- 230000035699 permeability Effects 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
Landscapes
- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Volume Flow (AREA)
Abstract
The invention provides a method and a device for measuring the flow velocity of fluid by nuclear magnetic resonance, wherein the method is applied to the device for measuring the flow velocity of the fluid by the nuclear magnetic resonance, and comprises the following steps: the pre-polarizing magnet section is used for pre-polarizing a fluid sample to be detected; the radio frequency antenna generates a resonance signal with the fluid sample to be tested after pre-polarization treatment under the action of the measuring magnet section, and transmits the resonance signal to the processing equipment; the processing device calculates the flow rate of the fluid sample to be measured according to the resonance signal. The method and the device for measuring the flow rate of the fluid by nuclear magnetic resonance can accurately measure the flow rate of the fluid sample to be measured when the flow rate of the fluid sample to be measured is higher, and the measurement of the flow rate of the fluid in different flow rate ranges is realized.
Description
Technical Field
The invention relates to a nuclear magnetic resonance technology, in particular to a method and a device for measuring the flow velocity of fluid by nuclear magnetic resonance.
Background
The Nuclear Magnetic Resonance fluid analyzer is an instrument for identifying fluid based on the Nuclear Magnetic Resonance (NMR) principle, and has the advantages of real time, rapidness and accuracy, so that the Nuclear Magnetic Resonance fluid analyzer is widely applied.
Nuclear magnetic resonance is also widely used in fluid flow rate measurement, and at present, there are two methods for measuring flow rate by NMR: one relies on a fixed gradient field or a radio frequency gradient field to derive fluid flow rate information by phase shifting the NMR signals generated by the fluid flow. Another method determines fluid flow rate based on changes in the magnitude of the NMR signal.
However, the NMR flow rate measurement methods of the prior art can only measure the flow rate of the fluid at a relatively low flow rate, and cannot measure the flow rate of the fluid at different flow rate ranges.
Disclosure of Invention
The invention provides a method and a device for measuring fluid flow rate by nuclear magnetic resonance, which are used for solving the problem that the method for measuring the flow rate by the NMR in the prior art can not realize the measurement of the fluid flow rate in different flow rate ranges.
In one aspect, the present invention provides a method for measuring a flow rate of a fluid by nuclear magnetic resonance, the method being applied to an apparatus for measuring a flow rate of a fluid by nuclear magnetic resonance, the apparatus comprising: the device comprises a fluid pipe, a magnet, at least two radio frequency antennas, a high-permeability shell and processing equipment; the fluid pipe is positioned in the high-permeability shell; the magnet comprises a pre-polarized magnet section and a measuring magnet section, and the magnet is sleeved outside the fluid pipe and is positioned between the high-permeability shell and the fluid pipe; the at least two radio frequency antennas are wound on the outer wall of the fluid pipe and are positioned between the measuring magnet section and the fluid pipe; the output ends of the at least two radio frequency antennas are connected with the processing equipment; the method comprises the following steps:
the pre-polarizing magnet section is used for pre-polarizing a fluid sample to be detected;
the radio frequency antenna generates a resonance signal with the fluid sample to be measured after pre-polarization treatment under the action of the measuring magnet section, and transmits the resonance signal to the processing equipment;
and the processing equipment calculates the flow speed of the fluid sample to be measured according to the resonance signal.
Further, the processing device calculates the flow rate of the fluid sample to be measured according to the resonance signal, and includes:
determining the phase of at least two echoes of the resonance signal to calculate the flow velocity of the fluid sample to be measured according to the attenuation curve characteristic of the echo train of the resonance signal; or,
and determining the flow velocity of the fluid sample to be measured by using the attenuation curve characteristic of the echo train of the resonance signal according to the attenuation curve characteristic of the echo train of the resonance signal.
Optionally, when the fluid sample to be tested is in a flowing state, hydrogen nuclei in fluid molecules are polarized by the pre-polarizing magnet segment, phases of odd waves in at least two echoes of the resonance signal are incompletely refocused, and phases of even waves in the at least two echoes are completely refocused;
the processing device calculates the flow velocity of the fluid sample to be measured by using the phases of at least two echoes of the resonance signal, and the processing device comprises:
the processing device acquires a phase difference between the odd-numbered wave and the even-numbered wave of the at least two echoes according to phases of the at least two echoes of the resonance signal;
and acquiring the flow velocity of the fluid sample to be measured according to the phase difference between the odd wave and the even wave in the at least two echoes.
Further, the acquiring a flow velocity of the fluid sample to be measured according to a phase difference between the odd-numbered wave and the even-numbered wave in the at least two echoes includes:
obtaining the flow rate of the fluid sample to be measured by adopting the following formula:
wherein,
gamma is the gyromagnetic ratio, G is the magnetic field gradient of the gradient magnetic field, v is the flow velocity, T is the phase difference between the odd number wave and the even number waveEThe echo intervals of the odd-numbered waves and the even-numbered waves.
Optionally, the calculating the flow speed of the fluid sample to be measured by using the attenuation curve characteristic of the echo train of the resonance signal includes:
the processing equipment acquires the transverse relaxation time T of the fluid sample to be measured after the pre-polarization treatment according to the attenuation curve characteristic of the echo train of the resonance signal2And longitudinal relaxation time T1；
Said processing device being based on said transverse relaxation time T2And longitudinal relaxation time T1Obtaining the flow velocity of the fluid sample to be detected;
wherein the transverse relaxation time T2And the above-mentioned longitudinal relaxation time T1The following formula is adopted to obtain:
wherein I (t) is the fluid magnetization vector at time t, I0Is the fluid initial magnetization vector, and t is the fluid decay time.
Further, said processing device is adapted to determine said transverse relaxation time T2And longitudinal relaxation time T1Obtaining the flow rate of the fluid sample to be measured, including:
calculated using the following formula:
wherein I (v, t) is the magnetization vector of the fluid having a flow velocity v at time t, L is the effective length of the RF antenna to which the pulse sequence is applied, β is the pre-polarization efficiency of the fluid sample to be tested, wherein,
when T is much smaller than T2And then, calculating the flow velocity of the fluid sample to be measured according to the following formula:
in another aspect, the present invention provides an apparatus for measuring a flow rate of a fluid by nuclear magnetic resonance, comprising: the device comprises a fluid pipe, a magnet, at least two radio frequency antennas, a high-permeability shell and processing equipment; the fluid pipe is positioned in the high-permeability shell; the magnet comprises a pre-polarized magnet section and a measuring magnet section, and the magnet is sleeved outside the fluid pipe and is positioned between the high-permeability shell and the fluid pipe; the at least two radio frequency antennas are wound on the outer wall of the fluid pipe and are positioned between the measuring magnet section and the fluid pipe; the output ends of the at least two radio frequency antennas are connected with the processing equipment;
the fluid pipe is used for accommodating a fluid sample to be tested;
the pre-polarizing magnet section is used for pre-polarizing the fluid sample to be detected;
the radio frequency antenna is used for generating a resonance signal with the fluid sample to be measured after pre-polarization treatment under the action of the measuring magnet section and transmitting the resonance signal to the processing equipment;
the processing device is used for calculating the flow speed of the fluid sample to be measured according to the resonance signal.
Optionally, said pre-polarized magnet segments comprise at least three magnet segments;
the at least three magnet segments include: an over-polarized magnet segment, an under-polarized magnet segment, and a stably polarized magnet segment;
the magnetic field strength of the over-polarized magnet section is greater than the magnetic field strength of the measuring magnet section, the magnetic field strength of the under-polarized magnet section is less than the magnetic field strength of the measuring magnet section, and the magnetic field strength of the stably polarized magnet section is equal to the magnetic field strength of the measuring magnet section.
Optionally, the measurement magnet segment includes: a uniform magnetic field magnet section and a gradient magnetic field magnet section;
the outer part of one end of the uniform magnetic field magnet section, which is close to the pre-polarized magnet section, is sleeved with a second antenna coil of the at least two radio-frequency antennas; the uniform magnetic field magnet section is used for generating a uniform magnetic field, so that the second antenna coil can generate a resonance signal with the high-speed fluid sample to be detected after pre-polarization treatment under the action of the measurement magnet section;
the gradient magnetic field magnet section is sleeved with a first antenna coil in the at least two radio frequency antennas; the gradient magnetic field magnet section is used for generating a gradient magnetic field so that the first antenna coil can generate a resonance signal with the low-speed fluid sample to be detected after the pre-polarization treatment under the action of the measurement magnet section;
wherein, the high-speed fluid sample to be measured is a fluid sample to be measured with the flow velocity of more than 15 cm/s; the low-speed fluid sample to be detected is a fluid sample to be detected with the flow speed of less than or equal to 15 cm/s;
the at least two radio frequency antennas can be used for transmitting a pulse sequence and receiving nuclear magnetic resonance signals returned by the fluid sample to be detected.
Optionally, the apparatus further comprises a third antenna coil;
the third antenna coil is sleeved outside one end of the uniform magnetic field magnet section, which is far away from the pre-polarization magnet section, and is used for assisting in measuring the fluid information of the fluid sample to be measured so as to distinguish the fluid types.
The invention provides a method and a device for measuring the flow velocity of fluid by nuclear magnetic resonance, which are applied to the device for measuring the flow velocity of fluid by nuclear magnetic resonance, and the device comprises: fluid pipe, magnet, at least two radio frequency antennas, high magnetic conductivity shell and treatment facility. The magnet comprises a pre-polarization magnet section and a measurement magnet section, when a fluid sample to be measured flows through a fluid pipe corresponding to the pre-polarization magnet section, pre-polarization treatment can be carried out on the fluid sample to be measured, the fluid sample to be measured after the pre-polarization treatment can generate a resonance signal with the radio frequency antenna under the action of the measurement magnet section, and the resonance signal is transmitted to the processing equipment through the radio frequency antenna so as to carry out flow rate calculation. The method and the device for measuring the flow rate of the fluid by nuclear magnetic resonance provided by the invention can ensure that the fluid sample to be measured can be accurately measured when the fluid sample to be measured has higher flow rate due to the pre-polarization treatment on the fluid sample to be measured, thereby realizing the measurement of the flow rate of the fluid in different flow rate ranges.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief description will be given below to the drawings required to be used in the description of the embodiments or the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
FIG. 1 is a schematic flow chart of a method for measuring a flow rate of a fluid by NMR according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of an apparatus for NMR measurement of fluid flow rate according to an embodiment of the invention;
FIG. 3 is a schematic diagram of a CPMG pulse sequence used in the method for measuring a fluid flow rate by nuclear magnetic resonance provided by the embodiment of the invention;
FIG. 4 is a flow chart of another method for measuring a flow rate of a fluid by NMR according to an embodiment of the invention;
FIG. 5 is a schematic flow chart of a method for calculating a flow rate of a low-speed fluid sample to be measured according to an embodiment of the present invention;
fig. 6 is a schematic phase diagram of odd waves and even waves when a fluid sample to be measured is in a flowing state according to an embodiment of the present invention;
fig. 7 is an echo train curve of a nuclear magnetic resonance signal of a low-speed fluid sample to be measured according to an embodiment of the present invention;
FIG. 8 is a schematic flow chart of a method for calculating a flow rate of a high-speed fluid sample to be measured according to an embodiment of the present invention;
fig. 9 is an echo train curve of a nuclear magnetic resonance signal of a high-speed fluid sample to be measured according to an embodiment of the present invention;
fig. 10 is a schematic structural diagram of another apparatus for measuring a flow rate of a fluid by nuclear magnetic resonance according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims. Furthermore, the terms "first" and "second" in the description are used merely for distinguishing and describing indicated technical features, and are not to be construed as indicating or implying relative importance or describing a particular order, it being understood that data so used may be interchanged where appropriate. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.
Fig. 1 is a schematic flow chart of a method for measuring a flow rate of a fluid by nuclear magnetic resonance according to an embodiment of the present invention, and fig. 2 is a schematic structural diagram of an apparatus for measuring a flow rate of a fluid by nuclear magnetic resonance according to an embodiment of the present invention. Referring to fig. 1, it should be noted that the method is applied to the apparatus for measuring a flow rate of a fluid by nuclear magnetic resonance shown in fig. 2.
Specifically, as shown in fig. 2, the apparatus includes: a fluid pipe 11, a magnet 12, at least two radio frequency antennas 13, a high permeability magnetic housing 14 and processing equipment (not shown in the figure); the fluid pipe 11 is positioned in the high-permeability shell 14; the magnet 12 comprises a pre-polarization magnet segment 121 and a measurement magnet segment 122, and the magnet 12 is sleeved outside the fluid pipe 11 and is located between the high-permeability shell 14 and the fluid pipe 11; at least two radio frequency antennas 13 are wound on the outer wall of the fluid pipe 11 and located between the measuring magnet section 122 and the fluid pipe 11; the outputs of the at least two radio frequency antennas 13 are connected to a processing device.
Based on the apparatus for measuring a flow rate of a fluid by nuclear magnetic resonance, the method for measuring a flow rate of a fluid by nuclear magnetic resonance provided by this embodiment includes:
s11: the pre-polarization magnet section performs pre-polarization treatment on the fluid sample to be detected.
Specifically, since the magnet of the apparatus for measuring a flow rate of a fluid by nuclear magnetic resonance includes a pre-polarizing magnet section and a measuring magnet section, when a fluid sample to be measured flows through the pre-polarizing magnet section, the fluid sample to be measured is pre-polarized under the action of a magnetic field of the pre-polarizing magnet section. The pre-polarization treatment can make the fluid sample to be measured fully polarized before the flow rate is measured, and because the flow rate of the fluid and the polarization degree of the fluid have influence on the nuclear magnetic resonance signal: the larger the flow velocity of the fluid, the faster the nuclear magnetic resonance signal decays; nuclear magnetic resonance is very sensitive to fluid polarization, and the higher the polarization degree is, the better the nuclear magnetic resonance effect is. Because the influence of the fluid flow velocity is inevitable, in order to improve the nuclear magnetic resonance effect to realize accurate measurement of the flow velocity, the nuclear magnetic resonance effect can be improved by improving the polarization degree of the fluid sample to be measured. In addition, since the pre-polarization treatment is carried out before the flow velocity measurement is carried out, the accurate flow velocity measurement can be realized for the high-speed fluid sample to be measured.
Alternatively, the pre-polarized magnet segments may be designed according to the properties of the fluid and the requirements of the pre-polarization degree, for example: selecting pre-polarized magnet segments of different magnetic field strengths, selecting pre-polarized magnet segments of different structures, and the like. The pre-polarization treatment effect of the fluid sample to be detected in the step can be realized through the design of the pre-polarization magnet section.
S12: the radio frequency antenna generates a resonance signal with the fluid sample to be tested after pre-polarization treatment under the action of the measuring magnet section, and transmits the resonance signal to the processing equipment.
In particular, the radio frequency antenna is used to transmit pulse sequences and receive resonance signals during fluid velocity measurements. When the radio frequency antenna sends a pulse sequence on the fluid sample to be measured, the fluid sample to be measured is positioned in the measuring magnet section, and a magnetic field exists in the measuring magnet section, so that under the action of the magnetic field of the measuring magnet section, the pulse sequence sent by the radio frequency antenna and the fluid sample to be measured after pre-polarization treatment act to generate a resonance signal, namely nuclear magnetic resonance occurs, a nuclear magnetic resonance signal is returned, and the nuclear magnetic resonance signal is transmitted to processing equipment with an operation processing function through the radio frequency antenna. Optionally, the measurement magnet segment may have a uniform magnetic field and a gradient magnetic field, and at the position of the gradient magnetic field, since the magnetic field applied to the fluid sample to be measured is the gradient magnetic field, the position can satisfy the measurement condition requirement of the diffusion coefficient of the fluid sample to be measured; at the position of the uniform magnetic field, the magnetic field applied to the fluid sample to be measured is the uniform magnetic field, so that the position can meet the measurement condition requirements of the nuclear magnetic parameters and/or the fluid information of the fluid sample to be measured.
Alternatively, the pulse sequence may be a CPMG (Carr-Purcel1-Meiboom-Gill, CPMG) pulse sequence, as shown in fig. 3, which is a schematic diagram of the CPMG pulse sequence used in the method for measuring a fluid flow rate by nuclear magnetic resonance provided in the embodiment of the present invention, referring to fig. 3, when the radio frequency antenna sends the CPMG pulse sequence to perform nuclear magnetic resonance, first, a 90 ° pulse flips a magnetization vector to a transverse plane, i.e., a plane perpendicular to a direction of a static magnetic field, at this time, the magnetization vector is gradually dephasing due to the influence of magnetic field inhomogeneity, etc., and then, after the 180 ° pulse flipping, the phase of the dephasing is inverted, so that the magnetization vector of the dephasing gradually refocusing, and at this time, the radio frequency antenna starts to receive a first echo signal. And then a series of echoes are obtained by repeatedly applying 180-degree pulses to form an echo string containing the nuclear magnetic resonance information of the fluid sample to be detected, wherein the echo string forms a resonance signal of the embodiment of the application.
S13: the processing device calculates the flow rate of the fluid sample to be measured according to the resonance signal.
Specifically, the processing equipment has analysis and operation processing functions, when the radio frequency antenna returns the resonance signal to the processing equipment, the processing equipment analyzes the resonance signal, and performs operation processing according to the characteristics of the resonance signal so as to calculate the flow velocity of the fluid sample to be measured and display and output the flow velocity. Alternatively, the processing device may be an upper Computer, and the upper Computer may be a device with a processing function, such as a Personal Computer (PC), and the like, and of course, the processing device may also be another entity device that can analyze and calculate the resonance signal, which is not limited in this embodiment of the application.
The method for measuring the flow rate of the fluid through the nuclear magnetic resonance provided by the embodiment is applied to a device for measuring the flow rate of the fluid through the nuclear magnetic resonance, the device is adopted to measure the flow rate of the fluid through the nuclear magnetic resonance, a fluid sample to be measured is subjected to pre-polarization treatment, the fluid sample to be measured after the pre-polarization treatment can generate a resonance signal with a radio frequency antenna under the action of a measuring magnet section, and the resonance signal is transmitted to a processing device through the radio frequency antenna so as to calculate the flow rate. The method for measuring the flow rate of the fluid through the nuclear magnetic resonance provided by the embodiment can ensure the polarization effect of the fluid sample to be measured due to the pre-polarization treatment of the fluid sample to be measured, can accurately measure the flow rate of the fluid sample to be measured when the fluid sample to be measured has higher flow rate, and realizes the measurement of the flow rate of the fluid in different flow rate ranges.
Fig. 4 is a flow chart illustrating another method for measuring a flow rate of a fluid by nuclear magnetic resonance according to an embodiment of the present invention, referring to fig. 4, based on the above embodiment, step S13 includes:
s131: and determining the phase of at least two echoes of the resonance signal to calculate the flow velocity of the fluid sample to be measured according to the attenuation curve characteristics of the echo train of the resonance signal.
Specifically, when the fluid sample to be measured is a low-speed fluid sample to be measured, a resonance signal is returned through a radio frequency antenna wound outside a fluid pipe corresponding to a gradient magnetic field magnet section of the measurement magnet section, and since a magnetic field applied to the fluid sample to be measured is a gradient magnetic field, the position can meet the measurement condition requirements of the diffusion coefficient of the fluid sample to be measured, and the diffusion coefficient influences the spatial position information of the fluid sample to be measured. Therefore, under certain conditions, the measured resonance signal can not only obtain the signal magnitude, but also obtain the information such as the spatial position, the flow velocity and the like of the fluid sample to be measured.
When the flow velocity of the fluid sample to be measured is stable, the flow velocity is measured in the gradient field, the spatial position information and the flow velocity information of the fluid sample to be measured need to be considered, and the two pieces of information can be converted into phase information of a resonance signal after Fourier transformation. Therefore, the judgment is carried out according to the attenuation curve characteristics of the echo train of the resonance signal, if the attenuation curve characteristics of the echo train are in a gentle attenuation trend, namely the relative amplitudes of the echo train of the resonance signal are all larger than zero, the fluid sample to be detected can be determined to be the low-speed fluid sample to be detected, and at the moment, the flow speed of the fluid sample to be detected is calculated by adopting the phases of at least two echoes of the resonance signal.
S132: and determining the flow speed of the fluid sample to be measured by adopting the attenuation curve characteristic of the echo train of the resonance signal according to the attenuation curve characteristic of the echo train of the resonance signal.
Specifically, when the rf antenna transmits the CPMG pulse sequence to perform nuclear magnetic resonance, first, a 90 ° pulse shifts the magnetization vector to a transverse plane, i.e., a plane perpendicular to the direction of the static magnetic field, at this time, the magnetization vector gradually looses phase due to the influence of magnetic field inhomogeneity, and then, after the 180 ° pulse shift, the phase of the dispersed phase is inverted, so that the magnetization vector of the dispersed phase gradually converges. However, in the process of re-aggregation, the phase of the dispersed phase caused by the interaction of the dipole-dipole and the like among molecules cannot be re-aggregated, a part of the signal is lost, and the part of the lost fluid is more serious than the fluid sample to be measured at a low speed when the lost fluid is a fluid sample to be measured at a high speed, so that the judgment needs to be carried out according to the attenuation curve characteristic of the echo train of the resonance signal.
Fig. 5 is a schematic flow chart of a method for calculating a flow rate of a low-speed fluid sample to be measured according to an embodiment of the present invention, and fig. 5 shows that the method includes:
s1311: the processing device acquires the phase difference between the odd waves and the even waves in the at least two echoes according to the phases of the at least two echoes of the resonance signal.
Specifically, after the processing device acquires the echo train of the resonance signal, the phase of the echo of the resonance signal is also acquired. Meanwhile, because the hydrogen nuclei in the fluid molecules are polarized by the pre-polarized magnet segment when the fluid sample to be tested is in the flowing state, and according to the characteristics of the CPMG pulse sequence, the echoes of the resonance signal returned by the fluid subjected to nuclear magnetic resonance have different expression forms in the odd waves and the even waves, the phases of the odd waves in at least two echoes of the resonance signal are incompletely refocused, and the phases of the even waves in at least two echoes are completely refocused, as shown in fig. 6, a schematic diagram of the phases of the odd waves and the even waves when the fluid sample to be tested is in the flowing state is provided for the embodiment of the present invention, and it can be seen from fig. 6 that, when the fluid sample to be tested is in the flowing state, the phases of the odd waves in the echoes of the resonance signal returned by the nuclear magnetic resonance signal to be tested are incompletely refocused, and the.
Meanwhile, referring to fig. 3, the echo returned after the first 180 ° pulse is an odd-numbered wave, the echo returned after the second 180 ° pulse is an even-numbered wave, and the processing device acquires a phase difference between the odd-numbered wave and the even-numbered wave in the at least two echoes according to the phases of the at least two echoes of the resonance signal, specifically, acquires a phase difference between the odd-numbered wave and the even-numbered wave in the at least two adjacent echoes according to the phases of the at least two adjacent echoes. Fig. 7 shows an echo train curve of a nuclear magnetic resonance signal of a low-speed fluid sample to be measured according to an embodiment of the present invention, where a curve 1 in fig. 7 is a contrast curve, that is, an echo train curve of a fixed fluid with a flow rate of zero, and a curve 2 is an echo train curve of a low-speed fluid sample to be measured. It can be seen that the fluid is at rest and has no phase difference, and when the fluid flows, the odd waves and the even waves have phase difference.
In addition, in the present embodiment, the number of at least two echoes is an even number of two, four, six, or the like, and the phase difference is obtained from the phase of the adjacent echo among the even number of echoes.
S1312: and acquiring the flow velocity of the fluid sample to be measured according to the phase difference between the odd waves and the even waves in the at least two echoes.
Specifically, the phases of the odd waves in the at least two echoes of the resonance signal are incompletely refocused, and the phases of the even waves in the at least two echoes are completely refocused, so that the phase difference between the formed odd waves and the even waves is just related to the flow velocity, and therefore, the flow velocity of the fluid sample to be measured can be obtained according to the phase difference between the odd waves and the even waves in the at least two echoes.
Further, on the basis of the above embodiment, obtaining the flow velocity of the fluid sample to be measured according to the phase difference between the odd wave and the even wave in the at least two echoes includes:
the flow rate of the fluid sample to be measured is obtained by adopting the following formula:
wherein,
is the phase difference between odd and even waves, gamma is the gyromagnetic ratio, G is the magnetic field gradient of the gradient magnetic field, v is the flow velocity, TEThe echo intervals of odd waves and even waves.
In a possible embodiment, if the first echo and the second echo are two adjacent echoes, where the first echo is an odd-numbered wave and the second echo is an even-numbered wave, the flow velocity of the fluid sample to be measured can be obtained according to a phase difference between the first echo and the second echo. For the measured echo signals, when the first echo amplitude is A1 and the second echo amplitude is A2, the formula
The phase difference between the first echo and the second echo can be obtained by a formula
Will be provided with
Bringing inThe above formula can calculate the flow rate of the fluid sample to be measured.
In another possible embodiment, if the four adjacent echoes are a first echo, a second echo, a third echo, and a fourth echo in sequence, the flow velocity of the fluid sample to be measured may be obtained according to a phase difference between the first echo, the second echo, the third echo, and the fourth echo. For the measured echo signals, when the first echo amplitude is a1, the second echo amplitude is a2, the third echo amplitude is A3, and the fourth echo amplitude is a4, the following formula can be expressed:
obtaining the phase difference of the four continuous echoes
Will be provided with
Substituting the above formula can also calculate the flow rate of the fluid sample to be measured.
Similarly, the flow speed of the fluid sample to be measured may be obtained according to the phase difference of the multiple echoes, and the number of the multiple echoes is an even number.
In the method for measuring a flow rate of a fluid by nuclear magnetic resonance provided by this embodiment, the processing device obtains a phase difference between an odd wave and an even wave in at least two echoes according to phases of the at least two echoes of the resonance signal, and then obtains the flow rate of the fluid sample to be measured according to the phase difference between the odd wave and the even wave in the at least two echoes. The method of the embodiment can realize the calculation of the flow velocity of the low-speed fluid sample to be measured through the phase difference.
Fig. 8 is a schematic flow chart of a method for calculating a flow rate of a high-speed fluid sample to be measured according to an embodiment of the present invention, and fig. 8 shows the method including:
s1321: the processing equipment obtains the transverse relaxation time T of the fluid sample to be tested after the pre-polarization treatment according to the attenuation curve characteristic of the echo train of the resonance signal2And longitudinal relaxation time T1。
In particular toFrom the above analysis, it is known that in the magnetization vector realignment process, the phase of the dispersed phase due to the influence of the intermolecular dipole-dipole interaction cannot be realigned, and a part of the signal is lost, and the lost signal is influenced by the transverse relaxation time T of the fluid sample to be measured2And longitudinal relaxation time T1Influence.
Wherein the transverse relaxation time T2And longitudinal relaxation time T1The following formula is adopted to obtain:
wherein I (t) is the fluid magnetization vector at time t, I0Is the fluid initial magnetization vector, and t is the fluid decay time.
As shown in fig. 9, an echo train curve of the nmr signal of the high-speed fluid sample to be measured according to the embodiment of the present invention can obtain I (t)/I at time t0The value is substituted into the above two formulas, then the transverse relaxation time T can be calculated2And longitudinal relaxation time T1。
As can be seen from fig. 9, the echo train curve of the high-speed fluid has a high attenuation speed, and the curve linearly attenuates in the first several tens of echoes of the echo train. Meanwhile, the attenuation curve characteristics of the fluid sample to be measured at 4 different flow rates are shown in fig. 9, wherein the higher the flow rate is, the faster the curve is attenuated.
S1322: the treatment apparatus being dependent on the transverse relaxation time T2And longitudinal relaxation time T1And acquiring the flow speed of the fluid sample to be measured.
When the processing equipment calculates the transverse relaxation time T according to the attenuation curve characteristic of the echo train of the fluid nuclear magnetic resonance signal2And longitudinal relaxation time T1Then, the transverse relaxation time T can be used2And longitudinal relaxation time T1Obtaining the flow to be measuredFlow rate of the bulk sample.
Specifically, since a part of the magnetization vector that has been flipped to the transverse plane flows out of the detection region of the rf antenna as the fluid flows, the volume of the fluid generating the resonance signal is less and less, and the following formula is satisfied:
wherein V (t) is the volume of the fluid generating the resonance signal at time t, V (0) is the volume of the sample excited by the rf antenna at the initial time, S is the cross-sectional area of the fluid tube, V is the fluid flow rate, and L is the effective length of the rf antenna applying the pulse sequence. Thus, according to the topological relationship between the magnetization vector and the fluid volume, for a flowing fluid, the signal decays as follows:
where I (v, t) is the magnetization vector of the fluid with flow velocity v at time t.
In addition, when the fluid sample to be tested flows at a high speed, the polarization time of the fluid sample to be tested is shortened, so that the magnetization vector of the fluid sample to be tested does not reach a complete polarization state, and the pre-polarization efficiency is as follows:
wherein β is the pre-polarization efficiency of the fluid sample to be tested.
Therefore, the resulting resonance signal should include the transverse relaxation time T2Longitudinal relaxation time T1And the influence of the pre-polarization efficiency of the fluid sample to be tested:
when T is much smaller than T2And then, the formula for calculating the flow velocity of the fluid sample to be measured is as follows:
therefore, the flow velocity of the fluid sample to be measured can be obtained through the above formula.
In the method for measuring the fluid flow rate by nuclear magnetic resonance provided by this embodiment, the processing device obtains the transverse relaxation time T of the pre-polarized fluid sample to be measured according to the attenuation curve characteristic of the echo train of the resonance signal2And longitudinal relaxation time T1Then, based on the transverse relaxation time T2And longitudinal relaxation time T1And acquiring the flow speed of the fluid sample to be measured. The method of the present embodiment passes the transverse relaxation time T2And longitudinal relaxation time T1The calculation of the flow velocity of the high-speed fluid sample to be measured can be realized.
Further, the present invention also provides an apparatus as shown in fig. 2. As shown in fig. 2, the apparatus includes: a fluid tube 11, a magnet 12, at least two rf antennas 13, a highly permeable housing 14 and processing equipment (not shown).
The fluid tube 11 is located within a highly permeable casing 14 for containing a fluid sample to be measured. Optionally, the high permeability casing 14 is a material that is not easily magnetized, such as titanium alloy, and the high permeability casing 14 functions as a magnetic field shield to prevent the magnetic field outside the device from affecting the measurement process.
The magnet 12 is sleeved outside the fluid pipe 11 and located between the high permeability casing 14 and the fluid pipe 11 for generating a magnetic field required by measurement. The magnet 12 includes a pre-polarizing magnet segment 121 and a measuring magnet segment 122, and the pre-polarizing magnet segment 121 is used to pre-polarize the fluid sample to be measured, so that the apparatus for measuring the flow rate of the nuclear magnetic resonance fluid according to this embodiment can achieve accurate flow rate measurement for the high-speed fluid sample to be measured.
At least two RF antennas 13 are disposed around the outer wall of the fluid pipe 11 and between the measurement magnet segment 122 and the fluid pipe 11. The output end of the radio frequency antenna 13 is connected to the processing device, and is configured to generate a resonance signal with the pre-polarized fluid sample to be measured under the action of the measurement magnet section 122, and transmit the resonance signal to the processing device. Optionally, the radio frequency antenna 13 may be one or more of a solenoid coil, a saddle coil, and the like, and the present embodiment does not limit the structure of the radio frequency antenna 13.
And the processing equipment is used for calculating the flow speed of the fluid sample to be measured according to the resonance signal, and the calculation method adopts the method of any one of the above embodiments. Alternatively, the processing device may be an upper Computer, such as a Personal Computer (PC), and of course, the processing device may also be other entity devices that can analyze and calculate the resonance signal, which is not limited in this embodiment of the present application.
The device for measuring the flow rate of the fluid by nuclear magnetic resonance provided by the embodiment comprises: the fluid pipe, the magnet, two at least radio frequency antennas, high magnetic conduction shell and treatment facility, because the magnet includes pre-polarization magnet section and measurement magnet section for when adopting the device of this embodiment to measure the fluid sample that awaits measuring, can carry out pre-polarization to the fluid sample that awaits measuring earlier, can guarantee the polarization effect of the fluid sample that awaits measuring like this, also can accurately measure its velocity of flow when the fluid sample that awaits measuring has higher velocity of flow, therefore can realize the measurement to the velocity of flow of the fluid of different velocity of flow scopes.
Fig. 10 is a schematic structural diagram of another apparatus for measuring a flow rate of a fluid by nuclear magnetic resonance according to an embodiment of the present invention, and referring to fig. 10, a pre-polarized magnet segment 121 includes at least three magnet segments based on the above embodiment. Wherein the at least three magnet segments comprise: an over-polarized magnet segment 1211, an under-polarized magnet segment 1212, and a stably polarized magnet segment 1213.
The magnetic field strength of the over-polarized magnet section 1211 is greater than the magnetic field strength of the measurement magnet section 122, the magnetic field strength of the under-polarized magnet section 1212 is less than the magnetic field strength of the measurement magnet section 122, and the magnetic field strength of the steadily polarized magnet section 1213 is equal to the magnetic field strength of the measurement magnet section 122. The pre-polarizing magnet section with the magnetic field intensity showing the high-low-high variation trend can realize effective pre-polarizing treatment on the fluid sample to be detected. Optionally, the pre-polarizing magnet segment 121 includes at least three magnet segments, it should be noted that the at least three magnet segments are three, six, nine, etc., and for each pre-polarizing magnet segment, it is required to satisfy that each three adjacent magnet segments from one end of the pre-polarizing magnet segment satisfy a trend of high-low-high variation of magnetic field strength, so as to implement pre-polarizing treatment on the fluid sample to be measured.
Further, the measurement magnet section 122 includes: a homogeneous magnetic field magnet section and a gradient magnetic field magnet section.
The uniform magnetic field magnet segment is close to the pre-polarization magnet segment 121, and can generate a uniform magnetic field, and the relaxation time of the fluid is required to obtain the flow speed in the flow speed measurement of the high-speed fluid sample to be measured, so that the uniform magnetic field generated by the uniform magnetic field magnet segment can meet the requirement of the transverse relaxation time T2And longitudinal relaxation time T1The measurement condition requirements of (1).
And the second antenna coil 13b of at least two radio frequency antennas is sleeved outside one end of the uniform magnetic field magnet segment close to the pre-polarized magnet segment. Therefore, under the action of the uniform magnetic field at the position, when the second antenna coil 13b applies a pulse sequence to the pre-polarized high-speed fluid sample to be measured, the second antenna coil 13b and the pre-polarized high-speed fluid sample to be measured can generate a resonance signal.
The gradient magnetic field magnet section is far away from the pre-polarizing magnet section 121, the gradient magnetic field magnet section can generate a gradient magnetic field, and in the flow velocity measurement of the low-speed fluid sample to be measured, the flow velocity of the fluid sample to be measured needs to be obtained according to the phase difference between the odd waves and the even waves in at least two echoes of the resonance signal, so that the gradient magnetic field generated by the gradient magnetic field magnet section can meet the measurement condition requirement of the diffusion coefficient.
And, the gradient magnetic field magnet section is sleeved with a first antenna coil 13a of at least two radio frequency antennas. Therefore, under the action of the position gradient magnetic field, when the first antenna coil 13a applies a pulse sequence to the pre-polarized low-speed fluid sample to be measured, the first antenna coil 13a and the pre-polarized high-speed fluid sample to be measured can generate a resonance signal.
The high-speed fluid sample to be measured is a fluid sample to be measured with the flow velocity of more than 15 cm/s; the low-speed fluid sample to be detected is a fluid sample to be detected with the flow speed of less than or equal to 15 cm/s.
And at least two radio frequency antennae can be used for transmitting the pulse sequence and receiving nuclear magnetic resonance signals returned by the fluid sample to be detected. Preferably, when the flow rate of the low-speed fluid sample to be measured is measured, the first antenna coil 13a is selected to transmit a pulse sequence and receive a nuclear magnetic resonance signal returned by the fluid sample to be measured; when measuring the flow rate of the high-speed fluid sample to be measured, the second antenna coil 13b is selected to transmit the pulse sequence and receive the nuclear magnetic resonance signal returned by the fluid sample to be measured.
With continued reference to fig. 10, on the basis of the above embodiment, the apparatus further includes a third antenna coil 13 c.
Specifically, the third antenna coil 13c is sleeved outside of one end of the uniform magnetic field magnet segment away from the pre-polarizing magnet segment 121, and is used for assisting in measuring fluid information of the fluid sample to be measured so as to distinguish fluid types. And, the magnetic field intensity of the end of the uniform magnetic field magnet section far away from the pre-polarizing magnet section 121 is most uniform, and a pulse is applied to the fluid sample to be measured through the third antenna coil 13c, so that the third antenna coil 13c and the fluid sample to be measured generate a resonance signal under the action of the uniform magnetic field, and the resonance signal can meet the accurate measurement of fluid information. The fluid information may be a fluid type, for example, crude oil or water. The third antenna coil 13c assists in measuring the type of the fluid, so that the flow rate of the fluid of which type is the flow rate can be determined after the flow rate is measured, and the fluid can be distinguished.
The device for measuring the flow rate of the fluid through nuclear magnetic resonance provided by the embodiment further comprises a third antenna coil for assisting in measuring the fluid information of the fluid sample to be measured, so that the device of the embodiment can realize the difference of fluid types while measuring the flow rate.
The device provided by the embodiment of the invention is used for executing the method embodiment, and the realization principle and the technical effect are similar.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (8)
1. A method for measuring a flow rate of a fluid by nuclear magnetic resonance, the method being applied to a device for measuring a flow rate of a fluid by nuclear magnetic resonance, the device comprising: the device comprises a fluid pipe, a magnet, at least two radio frequency antennas, a high-permeability shell and processing equipment; the fluid pipe is positioned in the high-permeability shell; the magnet comprises a pre-polarized magnet section and a measuring magnet section, the measuring magnet section comprises a uniform magnetic field magnet section and a gradient magnetic field magnet section, and a second antenna coil of the at least two radio-frequency antennas is sleeved outside one end, close to the pre-polarized magnet section, of the uniform magnetic field magnet section; the uniform magnetic field magnet section is used for generating a uniform magnetic field, so that the second antenna coil can generate a resonance signal with the high-speed fluid sample to be detected after pre-polarization treatment under the action of the measurement magnet section;
the gradient magnetic field magnet section is sleeved with a first antenna coil in the at least two radio frequency antennas; the gradient magnetic field magnet section is used for generating a gradient magnetic field so that the first antenna coil can generate a resonance signal with a low-speed fluid sample to be detected after pre-polarization treatment under the action of the measurement magnet section, wherein the high-speed fluid sample to be detected is a fluid sample to be detected with the flow speed of more than 15 cm/s; the low-speed fluid sample to be detected is a fluid sample to be detected with the flow speed of less than or equal to 15 cm/s; the at least two radio frequency antennas can be used for transmitting a pulse sequence and receiving nuclear magnetic resonance signals returned by the fluid sample to be detected, and the magnet is sleeved outside the fluid pipe and positioned between the high-permeability shell and the fluid pipe; the at least two radio frequency antennas are wound on the outer wall of the fluid pipe and are positioned between the measuring magnet section and the fluid pipe; the output ends of the at least two radio frequency antennas are connected with the processing equipment; the method comprises the following steps:
the pre-polarizing magnet section is used for pre-polarizing a fluid sample to be detected;
the radio frequency antenna generates a resonance signal with the fluid sample to be detected after pre-polarization treatment under the action of the measuring magnet section, and transmits the resonance signal to the processing equipment;
the processing equipment calculates the flow speed of the fluid sample to be detected according to the resonance signal;
the processing device calculates the flow speed of the fluid sample to be measured according to the resonance signal, and comprises:
determining the phase of at least two echoes of the resonance signal to calculate the flow velocity of the fluid sample to be measured according to the attenuation curve characteristic of the echo train of the resonance signal; or,
and determining and calculating the flow speed of the fluid sample to be measured by adopting the attenuation curve characteristic of the echo train of the resonance signal according to the attenuation curve characteristic of the echo train of the resonance signal.
2. The method of claim 1, wherein hydrogen nuclei in fluid molecules are polarized by the pre-polarizing magnet segment when the fluid sample to be tested is in a flow state, phases of odd-numbered waves of at least two echoes of the resonance signal are incompletely refocused, and phases of even-numbered waves of the at least two echoes are completely refocused;
the processing device calculates the flow velocity of the fluid sample to be measured by using the phases of at least two echoes of the resonance signal, and comprises:
the processing equipment acquires the phase difference between the odd waves and the even waves in at least two echoes according to the phases of the at least two echoes of the resonance signal;
and acquiring the flow velocity of the fluid sample to be detected according to the phase difference between the odd waves and the even waves in the at least two echoes.
3. The method according to claim 2, wherein the obtaining the flow velocity of the fluid sample to be tested according to the phase difference between the odd wave and the even wave in the at least two echoes comprises:
obtaining the flow rate of the fluid sample to be measured by adopting the following formula:
wherein,
is the phase difference between the odd-numbered wave and the even-numbered wave, gamma is the gyromagnetic ratio, G is the magnetic field gradient of the gradient magnetic field, v is the flow velocity, TEThe echo intervals of the odd waves and the even waves.
4. The method of claim 1, wherein said calculating the flow velocity of the fluid sample to be tested using the attenuation curve characteristic of the echo train of the resonance signal comprises:
the processing equipment acquires the transverse relaxation time T of the fluid sample to be tested after the pre-polarization treatment according to the attenuation curve characteristic of the echo train of the resonance signal2And longitudinal relaxation time T1；
Said processing device being dependent on said transverse relaxation time T2And longitudinal relaxation time T1Acquiring the flow velocity of the fluid sample to be detected;
wherein the transverse relaxation time T2And said longitudinal relaxation time T1The following formula is adopted to obtain:
wherein I (t) is the fluid magnetization vector at time t, I0Is the fluid initial magnetization vector, and t is the fluid decay time.
5. The method of claim 4,
said processing device being dependent on said transverse relaxation time T2And longitudinal relaxation time T1Obtaining the flow rate of the fluid sample to be measured, comprising:
calculated using the following formula:
wherein I (v, t) is the magnetization vector of the fluid having a flow velocity v at time t, L is the effective length of the RF antenna applying the pulse sequence, β is the pre-polarization efficiency of the fluid sample to be tested, wherein,
when T is much smaller than T2And then, calculating the flow velocity of the fluid sample to be measured according to the formula:
6. an apparatus for nuclear magnetic resonance measurement of fluid flow rate, comprising: the device comprises a fluid pipe, a magnet, at least two radio frequency antennas, a high-permeability shell and processing equipment; the fluid pipe is positioned in the high-permeability shell; the magnet comprises a pre-polarization magnet section and a measurement magnet section, and the magnet is sleeved outside the fluid pipe and is positioned between the high-permeability shell and the fluid pipe; the at least two radio frequency antennas are wound on the outer wall of the fluid pipe and are positioned between the measuring magnet section and the fluid pipe; the output ends of the at least two radio frequency antennas are connected with the processing equipment;
the fluid pipe is used for accommodating a fluid sample to be tested;
the pre-polarizing magnet section is used for pre-polarizing the fluid sample to be detected;
the radio frequency antenna is used for generating a resonance signal with the fluid sample to be detected after pre-polarization treatment under the action of the measuring magnet section and transmitting the resonance signal to the processing equipment;
the processing equipment is used for calculating the flow speed of the fluid sample to be detected according to the resonance signal;
the measurement magnet segment includes: a uniform magnetic field magnet section and a gradient magnetic field magnet section;
the outer part of one end of the uniform magnetic field magnet section, which is close to the pre-polarized magnet section, is sleeved with a second antenna coil of the at least two radio-frequency antennas; the uniform magnetic field magnet section is used for generating a uniform magnetic field, so that the second antenna coil can generate a resonance signal with the high-speed fluid sample to be detected after pre-polarization treatment under the action of the measurement magnet section;
the gradient magnetic field magnet section is sleeved with a first antenna coil in the at least two radio frequency antennas; the gradient magnetic field magnet section is used for generating a gradient magnetic field so that the first antenna coil can generate a resonance signal with the low-speed fluid sample to be detected after pre-polarization treatment under the action of the measurement magnet section;
the high-speed fluid sample to be detected is a fluid sample to be detected with the flow speed of more than 15 cm/s; the low-speed fluid sample to be detected is a fluid sample to be detected with the flow speed of less than or equal to 15 cm/s;
the at least two radio frequency antennas can be used for transmitting a pulse sequence and receiving nuclear magnetic resonance signals returned by the fluid sample to be tested.
7. The apparatus of claim 6, wherein the pre-polarized magnet segments comprise at least three magnet segments;
the at least three segments of magnet segments include: an over-polarized magnet segment, an under-polarized magnet segment, and a stably polarized magnet segment;
the magnetic field intensity of the over-polarized magnet segment is greater than the magnetic field intensity of the measuring magnet segment, the magnetic field intensity of the under-polarized magnet segment is less than the magnetic field intensity of the measuring magnet segment, and the magnetic field intensity of the stable polarized magnet segment is equal to the magnetic field intensity of the measuring magnet segment.
8. The apparatus of claim 7, further comprising a third antenna coil;
the third antenna coil is sleeved outside one end, far away from the pre-polarization magnet section, of the uniform magnetic field magnet section and used for assisting in measuring fluid information of the fluid sample to be measured so as to distinguish fluid types.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810025634.0A CN108254588B (en) | 2018-01-11 | 2018-01-11 | Method and device for measuring flow velocity of fluid by nuclear magnetic resonance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810025634.0A CN108254588B (en) | 2018-01-11 | 2018-01-11 | Method and device for measuring flow velocity of fluid by nuclear magnetic resonance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108254588A CN108254588A (en) | 2018-07-06 |
| CN108254588B true CN108254588B (en) | 2020-06-09 |
Family
ID=62726175
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810025634.0A Active CN108254588B (en) | 2018-01-11 | 2018-01-11 | Method and device for measuring flow velocity of fluid by nuclear magnetic resonance |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108254588B (en) |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1070042C (en) * | 1994-08-04 | 2001-08-29 | 深圳安科高技术有限公司 | Phase speed measuring method of magnetic resonance presentation |
| US6528995B1 (en) * | 2001-09-10 | 2003-03-04 | Schlumberger Technology Corporation | Methods and apparatus for measuring flow velocity in a wellbore using NMR and applications using same |
| US6952096B2 (en) * | 2003-09-05 | 2005-10-04 | Schlumberger Technology Corporation | Method and apparatus for determining speed and properties of flowing fluids using NMR measurements |
| CN1760508A (en) * | 2005-07-07 | 2006-04-19 | 中国石化集团胜利石油管理局测井公司 | Well logger of nuclear magnetic resonance |
| CN103364746B (en) * | 2013-07-10 | 2016-06-29 | 北京汇影互联科技有限公司 | The gradient intensity of magnetic resonance system and the method for testing of gradient switching rate |
| CN106124798A (en) * | 2016-06-14 | 2016-11-16 | 大连理工大学 | A kind of based on the method for convection current mixed process velocity field in NMR (Nuclear Magnetic Resonance)-imaging measurement porous media |
| CN107525819A (en) * | 2017-07-17 | 2017-12-29 | 中国石油大学(北京) | Nuclear magnetic resonance analysis of fluid instrument probe and nuclear magnetic resonance analysis of fluid instrument |
-
2018
- 2018-01-11 CN CN201810025634.0A patent/CN108254588B/en active Active
Non-Patent Citations (1)
| Title |
|---|
| 《Broadband Analysis of Response From Magnetic Cores Used in Inductive Sensors for Pulsed Nuclear Magnetic Resonance Applications》;N. G. Prabhu Gaunkar1;《 IEEE Transactions on Magnetics 》;20161111;第52卷(第7期);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN108254588A (en) | 2018-07-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Morrell | A phase‐sensitive method of flip angle mapping | |
| US7719267B2 (en) | Apparatus and method for real time and real flow-rates measurements of oil and water cuts from oil production | |
| US7459907B2 (en) | Flow measurement using NMR | |
| US7852074B2 (en) | Apparatus and method for measuring cased hole fluid flow with NMR | |
| EP0233906B1 (en) | Magnetic resonance imaging of high velocity flows | |
| AU2014364155B2 (en) | Method of interpreting NMR signals to give multiphase fluid flow measurements for a gas/liquid system | |
| US5585720A (en) | Signal processing method for multiexponentially decaying signals and application to nuclear magnetic resonance well logging tools | |
| Zheng et al. | Suppression of background gradients in (B0 gradient‐based) NMR diffusion experiments | |
| CN105334239A (en) | Multi-dimensional nuclear magnetic resonance fluid component content measuring method and device | |
| JP2015155905A (en) | Flowmeter having measurement device performing measurement principle of tomography | |
| US10782257B2 (en) | Composite FID-CPMG process for fast relaxing media determination | |
| Appel et al. | Robust multi-phase flow measurement using magnetic resonance technology | |
| O’Neill et al. | Quantitative velocity distributions via nuclear magnetic resonance flow metering | |
| CA2594055C (en) | Method for determining more accurate diffusion coefficient distributions of reservoir fluids using bi-polar pulsed field gradients | |
| Hogendoorn et al. | Magnetic Resonance Technology, A New Concept for Multiphase Flow Measurement | |
| Zargar et al. | Nuclear magnetic resonance multiphase flowmeters: Current status and future prospects | |
| EP1384097B1 (en) | Estimation of transversal motion of the nmr tool during logging | |
| Casieri et al. | Self-diffusion coefficient by single-sided NMR | |
| CN108426909B (en) | Method and device for synchronously and rapidly measuring nuclear magnetic resonance relaxation time and flow velocity | |
| CN108254588B (en) | Method and device for measuring flow velocity of fluid by nuclear magnetic resonance | |
| US10371653B2 (en) | Multi-phase metering device for oilfield applications | |
| JP2023156431A (en) | System and method for imaging tissue | |
| US5309099A (en) | Method of determining real-time spatially localized velocity distribution using magnetic resonance measurements | |
| Zubkov et al. | Steady state effects in a two-pulse diffusion-weighted sequence | |
| CN105352847B (en) | Viscosity of crude method for fast measuring |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |