CN107703174B - Nuclear magnetic resonance fluid analyzer and preparation method thereof - Google Patents
Nuclear magnetic resonance fluid analyzer and preparation method thereof Download PDFInfo
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Abstract
The application provides a nuclear magnetic resonance fluid analyzer and a preparation method thereof. The nuclear magnetic resonance fluid analyzer includes: the fluid pipe is used for circulating fluid, a pre-polarized magnet array and a detection magnet array are sequentially and annularly arranged on the radial outer side of the fluid pipe along the fluid flowing direction, an antenna is arranged on the outer surface of the fluid pipe, and the antenna is arranged in a magnetic field area generated by the detection magnet array; the detection magnet array adopts a double-ring Halbach structure. By utilizing the embodiments in the application, the polarization time of the fluid is increased, the accuracy and the signal to noise ratio of fluid detection are improved, the environmental adaptability of the nuclear magnetic resonance fluid analyzer is improved, and the method is suitable for field operation.
Description
Technical Field
The application belongs to the technical field of fluid analysis application, and particularly relates to a nuclear magnetic resonance fluid analyzer and a preparation method thereof.
Background
The nuclear magnetic resonance technology is widely applied to fluid identification in oil and gas exploration and development, and one-dimensional and multi-dimensional qualitative and quantitative identification can be carried out on the fluid by measuring parameters such as longitudinal relaxation time, transverse relaxation time, diffusion coefficient and the like of the fluid. The downhole fluid analyzer based on the nuclear magnetic resonance principle has the advantages of real-time, rapidness and accuracy in fluid identification.
In the prior art, low-field nuclear magnetic resonance techniques are commonly used for the analysis of fluid components. The low-field nuclear magnetic resonance technology mainly adopts a static measurement mode, namely, the nuclear magnetic resonance signals are measured under the state that a sample and a probe are kept relatively static. The online nuclear magnetic resonance detection of the fluid takes the hydrogen nuclei of the fast flowing fluid in the nuclear magnetic pipeline as basic detection and research objects, and the continuous change of the flow rate and the flow state of the fluid puts very strict requirements on the accuracy, reliability, timeliness and high efficiency of a nuclear magnetic resonance detection instrument. The nuclear magnetic resonance measurement in the flow state can face a plurality of problems, including insufficient polarization time, signal acquisition loss, large apparent diffusion coefficient of fluid and the like, and the measurement accuracy is seriously influenced. Therefore, there is a need for an nmr fluid analyzer that can improve the accuracy of fluid detection.
Disclosure of Invention
The application aims to provide a nuclear magnetic resonance fluid analyzer and a preparation method thereof. The accuracy and the signal-to-noise ratio of the fluid detection are improved, and the method has strong environmental adaptability and is suitable for field operation.
In one aspect, the present application provides a nuclear magnetic resonance fluid analyzer comprising:
the fluid pipe is used for circulating fluid, a pre-polarized magnet array and a detection magnet array are sequentially and annularly arranged on the radial outer side of the fluid pipe along the fluid flowing direction, an antenna is arranged on the outer surface of the fluid pipe, and the antenna is arranged in a magnetic field area generated by the detection magnet array;
the detection magnet array adopts a double-ring Halbach structure.
Further, in another embodiment of the nuclear magnetic resonance fluid analyzer, the probe magnet array includes an inner ring including a plurality of octagonal first magnet segments and an outer ring including a plurality of octagonal second magnet segments.
Further, in another embodiment of the nmr fluid analyzer, the number of the first magnet pieces and the number of the second magnet pieces in the probe magnet array are the same.
Further, in another embodiment of the nmr fluid analyzer, the pre-polarizing magnet array is of a single-ring Halbach structure.
Further, in another embodiment of the nmr fluid analyzer, the pre-polarizing magnet array includes a plurality of third octagonal magnet blocks therein.
Further, in another embodiment of the nmr fluid analyzer, the central magnetic field strength of the pre-polarizing magnet array is greater than the central magnetic field strength of the probe magnet array.
Further, in another embodiment of the nmr fluid analyzer, the pre-polarizing magnet array and the detecting magnet array are separated by a field strength decay distance of a predetermined length.
Further, in another embodiment of the nmr fluid analyzer, the probe magnet array includes a plurality of segments of first ring magnet units, and the first ring magnet units are spaced at different intervals.
Further, in another embodiment of the nmr fluid analyzer, the pre-polarizing magnet array includes a plurality of segments of second ring-shaped magnet units, and the spacing between each segment of the second ring-shaped magnet units is the same.
Further, in another embodiment of the nmr fluid analyzer, a main antenna is provided within the homogeneous magnetic field region generated by the probe magnet array and a secondary antenna is provided within the gradient magnetic field region generated by the probe magnet array.
Further, in another embodiment of the nmr fluid analyzer, a thermal insulation layer is disposed inside the pre-polarizing magnet array and the detecting magnet array, and is configured to stabilize the temperature inside the pre-polarizing magnet array and the detecting magnet array;
a temperature control system is arranged on the pre-polarizing magnet array and the detecting magnet array, and the temperature control system is used for controlling the temperature change in the pre-polarizing magnet array and the detecting magnet array.
Further, in another embodiment of the nmr fluid analyzer, the length of the pre-polarizing magnet array is greater than the length of the probe magnet array.
Further, in another embodiment of the nmr fluid analyzer, a magnetically conductive housing having a magnetic field shielding effect is disposed outside the pre-polarizing magnet array and the probe magnet array.
Further, in another embodiment of the nmr fluid analyzer, the magnet material in the pre-polarizing magnet array and the detecting magnet array is samarium cobalt permanent magnets.
In another aspect, the present application provides a method for manufacturing a nuclear magnetic resonance fluid analyzer, including: arranging a fluid pipe for flowing fluid, and sequentially and annularly arranging a pre-polarized magnet array and a detection magnet array on the radial outer side of the fluid pipe along the fluid flowing direction;
wherein, the detection magnet array adopts a double-ring Halbach structure.
The application provides a nuclear magnetic resonance fluid analyzer and preparation method thereof, through setting up the pre-polarization magnet array to can set up the central magnetic field intensity of pre-polarization magnet array to be a little higher than the central magnetic field intensity of surveying the magnet array, can polarize the fluid that flows through fast, the fluid after the polarization flows into surveys the magnet array region. The polarization time of the fluid is prolonged, and the accuracy, efficiency and maximum displacement of fluid detection are improved. Meanwhile, the detection magnet array of the detection region adopts a double-ring Halbach structure, so that the magnetic field of the detection region is more uniform, and the accuracy and the signal-to-noise ratio of fluid detection are improved. In addition, this application adopts the magnet outside, to inside radiation magnetic field's closed magnetic field structure, can install temperature control system, malleation unit etc. additional inside, and adverse effect such as magnetic field intensity drift, erosion, electromagnetic interference that isolated outside ambient temperature, humidity, dust etc. brought to probe inside. The environmental adaptability of the nuclear magnetic resonance fluid analyzer is improved, and the nuclear magnetic resonance fluid analyzer is suitable for field operation.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without any creative effort.
FIG. 1 is a schematic diagram of a nuclear magnetic resonance fluid analyzer according to the present application;
FIG. 2 is a schematic cross-sectional view of an exemplary probe magnet array of the present application;
FIG. 3 is a schematic diagram illustrating echo train head amplitudes of multiphase flows with different water contents corresponding to different lengths of pre-polarized magnet arrays in an embodiment of the present application;
FIG. 4 is an axial magnetic field profile generated by a probe magnet array in an embodiment of the present application;
FIG. 5 is a schematic cross-sectional view of an embodiment of a pre-polarized magnet array of the present application;
FIG. 6 is a schematic three-dimensional view of an NMR fluid analyzer according to an embodiment of the present disclosure;
FIG. 7 is a schematic illustration of the magnetic field distribution of an NMR fluid analyzer along the fluid direction in one embodiment of the application.
Detailed Description
In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the 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 application.
A nmr downhole fluid analyzer generally includes a magnet for generating a static magnetic field inside a cavity of the nmr downhole fluid analyzer to polarize hydrogen atoms of fluid therein and an antenna. The antenna is mainly used for transmitting radio frequency pulses to the fluid to form a pulse magnetic field, exciting hydrogen atoms polarized by the static magnetic field to generate a nuclear magnetic resonance phenomenon, and receiving and collecting nuclear magnetic resonance signals generated by the excited hydrogen atoms.
The online nuclear magnetic resonance detection of the fluid takes the hydrogen nuclei of the fast flowing fluid in a nuclear magnetic pipeline as a basic detection and research object. The fluid passes through a pipeline of the nuclear magnetic resonance fluid analyzer and is polarized by a magnet in the nuclear magnetic resonance fluid analyzer, and an antenna in the nuclear magnetic resonance fluid analyzer emits radio-frequency pulses to the fluid to form a pulse magnetic field and excite hydrogen atoms polarized by the static magnetic field to generate a nuclear magnetic resonance phenomenon. The antenna receives and collects nuclear magnetic resonance signals generated by hydrogen atoms in the excited fluid, and the analysis of the fluid components is completed according to the received signals.
Fig. 1 is a schematic structural diagram of an nmr fluid analyzer provided in the present application, and as shown in fig. 1, the nmr fluid analyzer provided in the present application includes:
the fluid pipe 1 for fluid circulation, the structural size and the material of the fluid pipe 1 can be set according to the requirement, and the application is not limited specifically. In one embodiment of the present application, the fluid pipe 1 may be made of glass fiber reinforced plastic epoxy resin, the inner diameter of the fluid pipe 1 may be set to 32mm (1.25inch), the wall thickness may be set to 10mm, and the length may be set to about 1.5 m.
As shown in fig. 1, a pre-polarization magnet array 2 and a detection magnet array 3 are sequentially and annularly arranged on the radial outer side of a fluid pipe 1 along the fluid flow direction, and an antenna 4 is arranged on the outer surface of the fluid pipe 1. The pre-polarizing magnet array 2 and the detecting magnet array 3 may each include a plurality of magnet blocks. Of course, the nmr fluid analyzer may also include other structures not shown in fig. 1, such as: signal measurement circuitry, a magnet holder, etc., and embodiments of the present application are not particularly limited. The pre-polarizing magnet array 2 and the detecting magnet array 3 may be fixed by a magnet holder, and a specific fixing method is not particularly limited in the present application. The pre-polarizing magnet array 2 and the detecting magnet array 3 may be coaxially arranged around the radial outside of the fluid pipe 1 to ensure the uniformity of the magnetic field.
The detection magnet array 3 adopts a double-ring Halbach structure, and the antenna 4 is arranged in a magnetic field area generated by the detection magnet array 3. The Halbach magnet structure refers to the use of a special arrangement of magnet elements to increase the field strength per unit direction with the goal of producing the strongest magnetic field with the least amount of magnet. The double ring Halbach structure may include an inner ring Halbach structure and an outer ring Halbach structure. Fig. 2 is a schematic cross-sectional structure diagram of a detection magnet array in an embodiment of the present application, and as shown in fig. 2, in an embodiment of the present application, the magnet blocks of the inner ring of the detection magnet array are configured as a Halbach structure magnet array, and the magnet blocks of the outer ring are also configured as a Halbach structure magnet array. The detection magnet array 3 with the double-ring Halbach structure can generate a more uniform internal magnetic field, particularly a uniform magnetic field can be generated near the middle area of the detection magnet array 3, and a gradient magnetic field is generated near the tail of the detection magnet array 3.
As shown in fig. 1, in one embodiment of the present application, a main antenna 41 and an auxiliary antenna 42 may be provided, and the main antenna 41 may be provided near the middle of the area of the detection magnet array 3, that is, the main antenna 41 may be provided in the uniform magnetic field area. The auxiliary antenna 42 may be arranged near the end of the area of the detection magnet array 3, i.e. the auxiliary antenna 42 is arranged in the gradient magnetic field area. When the shape and the placement position of the detection magnet array 3 and the pre-polarization magnet array 2 change, the magnetic field formed by the detection magnet array 3 and the pre-polarization magnet array 2 also changes, and the positions of the main antenna 41 and the auxiliary antenna 42 also change accordingly, as long as the main antenna 41 is placed at the uniform magnetic field generated by the detection magnet array 3, and the auxiliary antenna 42 is placed at the gradient magnetic field generated by the detection magnet array 3.
When a multiphase fluid (such as oil, gas and water mixed industrial oil flow) flows into a fluid pipe 1 of the nuclear magnetic resonance fluid analyzer, the multiphase fluid passes through the polarization of the pre-polarization magnet array 2 and enters a magnetic field area of the detection magnet array 3. The main antenna 41 may be used to measure multiphase flowRelaxation time (T) of1，T2) And an average flow velocity (v) that can be used to measure the diffusion coefficient (D) of the multiphase flow when the relaxation time is not able to distinguish the components of the multiphase flow. The magnetic field region corresponding to the detection magnet array has a uniform magnetic field region required for detecting the relaxation time characteristic of the fluid, and simultaneously has a gradient magnetic field region for detecting the diffusion coefficient of the fluid.
In one embodiment of the present application, the length of the pre-polarizing magnet array may be set to be greater than the length of the detecting magnet array, so that the fluid has sufficient polarization time and the polarizability of the fluid is improved. Theoretically, the longer the length of the pre-polarized magnet array is, the better, but the length of the pre-polarized magnet array is set as required by considering the problems of field operation installation and transportation and the economic problem caused by the longer magnet structure. FIG. 3 is a schematic diagram of echo train head amplitudes of multiphase flows with different water contents corresponding to different pre-polarization magnet array lengths in an embodiment of the present application, where L in FIG. 3pThe length of the pre-polarized magnet array is shown. As shown in fig. 3, the longitudinal relaxation time T due to water1And the amplitude of the first echo of the multiphase flow with 100% water is relatively low. According to one embodiment of the application, the magnetization efficiency of a multiphase flow flowing into a detection magnet array region under an extreme condition (100% water content) can be selected to be more than 20%, namely, the length of a pre-polarization magnet array is at least 500mm, so that the accuracy of measurement is ensured, and meanwhile, the echo train data has a good SNR (Signal Noise Ratio). As shown in fig. 1, in one embodiment of the present application, the length of the pre-polarizing magnet array may be set to 573mm, and the length of the detecting magnet array may be set to 312 mm. Therefore, the fluid can be ensured to have enough polarization time, and meanwhile, the nuclear magnetic resonance fluid analyzer is simple in structure and convenient to mount and carry.
The material of the magnets in the pre-polarized magnet array and the detection magnet array can be selected according to the requirement, and the performance parameters of the permanent magnet material are comprehensively considered in one embodiment of the application, such as: the samarium cobalt permanent magnet can be selected as the material of the magnets in the pre-polarized magnet array and the detection magnet array.
On the basis of the embodiment, the high-permeability shell can be arranged outside the pre-polarized magnet array and the detection magnet array, magnetic leakage of the pre-polarized magnet array and the detection magnet array is avoided, and safety of workers around the nuclear magnetic resonance fluid analyzer is improved. Meanwhile, the safety of the nuclear magnetic resonance fluid analyzer can be improved, so that the nuclear magnetic resonance fluid analyzer can be used outdoors, and the applicability of the nuclear magnetic resonance fluid analyzer is improved.
In addition, as shown in fig. 1, in an embodiment of the present application, a thermal insulation layer 5 may be further disposed inside the pre-polarizing magnet array and the detecting magnet array, and the thermal insulation layer 5 may be used to stabilize the temperature inside the pre-polarizing magnet array and the detecting magnet array, and reduce the influence of external temperature changes on the internal magnetic field of the magnet array. Temperature control systems can be arranged on the magnets of the pre-polarization magnet array and the detection magnet array and used for controlling the temperature change in the pre-polarization magnet array and the detection magnet array, and the temperature in the magnet array can be adjusted through the temperature control systems to ensure the constancy of the temperature in the magnet array. For example: if the temperature in the magnet array is increased due to the change of the external environment, the temperature in the magnet array can be reduced through the temperature control system. The device can avoid the influence of the great day and night temperature difference on the center frequency of the magnet on the oil field site and prevent temperature drift. The positive pressure unit and other structures can be arranged on the magnets of the pre-polarized magnet array and the detection magnet array, so that the influence of the external environment on the internal magnetic field of the nuclear magnetic resonance fluid analyzer is avoided.
The application provides a nuclear magnetic resonance fluid analysis appearance can polarize the fluid of flowing through fast through setting up the pre-polarization magnet array, and the fluid inflow after the polarization surveys the magnet array region. The detection magnet array with the double-ring Halbach structure can generate a more uniform internal magnetic field, and the accuracy and the signal-to-noise ratio of fluid detection are improved. Meanwhile, the closed magnetic field structure that the magnet is arranged outside and radiates a magnetic field to the inside can be internally provided with a temperature control system, a positive pressure unit and the like, so that adverse effects of magnetic field intensity drift, erosion, electromagnetic interference and the like caused by external environment temperature, humidity, dust and the like to the inside of the probe are isolated. The nuclear magnetic resonance fluid analyzer has strong environmental adaptability and is suitable for field operation.
On the basis of the above embodiment, the detection magnet array includes an inner ring including a plurality of octagonal first magnet pieces and an outer ring including a plurality of octagonal second magnet pieces.
In one embodiment of the present application, as shown in fig. 2, the magnets in the detection magnet array of the double-ring Halbach magnet array are each octagonal, the inner ring includes a plurality of octagonal first magnet segments, and the outer ring includes a plurality of octagonal second magnet segments. The direction of the arrow in fig. 3 can indicate the magnetizing direction of each magnet, and the magnetic field generated by the magnet blocks with the octagonal structure adopted in the application is better in uniformity. And the magnet piece of octagon all can follow same direction trompil when the trompil of magnet skeleton, all need rotate different angles in every hole compared with square magnet, and it is easier to process and install. Of course, the magnet block may have a symmetrical structure such as a hexadecagon shape as needed, and the present application is not limited to this.
As shown in fig. 2, the number of the first magnet pieces of the inner ring and the number of the second magnet pieces of the outer ring in the detection magnet array of the double-ring Halbach structure are the same, which ensures that the detection magnet array generates a more uniform magnetic field. The first magnet blocks of the inner ring in the detection magnet array are the same size and the second magnet blocks of the outer ring in the detection magnet array are the same size to ensure that the detection magnet array produces a more uniform magnetic field. FIG. 4 is a graph showing the distribution of the axial magnetic field generated by the probe magnet array according to an embodiment of the present invention, and as shown in FIG. 4, the magnets of the probe magnet array can generate a uniform region of 40mm in the axial direction, which is located at the center of the magnets, and the fluctuation of the magnetic field in the probe magnet array region is less than 1Gauss, and the uniformity of the magnetic field is 348.3 ppm.
Fig. 5 is a schematic cross-sectional structure diagram of a pre-polarized magnet array in an embodiment of the present application, and the direction of the arrow in fig. 5 may indicate the magnetizing direction of each magnet. As shown in fig. 5, the pre-polarized magnet array in the present application may adopt a single-ring Halbach structure, and the pre-polarized magnet array in the single-ring Halbach structure may include a plurality of third magnet blocks having an octagonal shape. The pre-polarized magnet array of the single-ring Halbach configuration of figure 5 comprises 8 octagonal third magnet blocks.
In one embodiment of the present application, the magnet blocks in the pre-polarizing magnet array and the detecting magnet array may both have an octagonal structure, but may also have other structures such as 4-sided polygon or 16-sided polygon as required. Likewise, the structures of the magnet blocks in the pre-polarizing magnet array and the detecting magnet array may be different, such as: the pre-polarizing magnet array uses square magnet blocks, and the detecting magnet array uses octagonal magnet blocks. If the magnet blocks in the pre-polarization magnet array and the detection magnet array are all in an octagonal structure, the sizes of the first magnet block, the second magnet block and the third magnet block may be different, of course, the size of the third magnet block may also be the same as that of the second magnet block, the size of the third magnet block may also be the same as that of the first magnet block, and the size of the third magnet block may specifically be set according to actual needs, which is not specifically limited in the present application. The outer diameter of the cross section of the pre-polarizing magnet array can be the same as the outer diameter of the cross section of the inner ring in the detection magnet array, and of course, other arrangements can be made according to the needs. That is, the size and number of the magnet blocks in the pre-polarizing magnet array and the detecting magnet array can be set according to the requirement, for example, the size and number can be determined by optimization design or simulation experiment, and the application is not limited specifically.
The application provides a nuclear magnetic resonance fluid analyzer sets up the pre-polarization magnet array into the monocycle Halbach structure, not only can ensure that the fluid polarizes fast to for the material of dicyclo Halbach structure practiced thrift the magnet, simplified nuclear magnetic resonance fluid analyzer's structure, simultaneously, practiced thrift the cost.
Of course, the pre-polarizing magnet array may be configured as a double-ring Halbach structure as required, but the structure is slightly complicated and the cost is increased, but the magnetic field generated by the pre-polarizing magnet array is more uniform, which is more beneficial to the polarization of the fluid.
On the basis of the above-described embodiments, in one embodiment of the present application, the central magnetic field strength of the pre-polarizing magnet array may be set higher than the central magnetic field strength of the detecting magnet array. The difference value of the central magnetic field intensity of the pre-polarized magnet array and the central magnetic field intensity of the detection magnet array can be obtained through optimization design or simulation, and the corresponding difference value of the magnetic field intensities when the fluid is rapidly polarized can be obtained. The magnitude and setting method of the difference between the central magnetic field strength of the pre-polarizing magnet array and the central magnetic field strength of the detecting magnet array is not particularly limited in this application. For example: the central magnetic field strength of the pre-polarizing magnet array may be set slightly higher than the central magnetic field strength of the detecting magnet array, such as: in one embodiment of the present application, the central magnetic field strength of the pre-polarizing magnet array may be set to 3700Gauss and the central magnetic field strength of the probing magnet array may be set to 3400 Gauss. Therefore, the fluid can be ensured to be quickly polarized when passing through the area corresponding to the pre-polarized magnet array, the field intensity of the detection magnet array can be quickly recovered when the polarized fluid flows into the detection magnet array, and the detection maximum discharge capacity of the nuclear magnetic resonance fluid analyzer is improved.
Based on the above embodiment, as shown in fig. 1, in one implementation of the present application, a field intensity attenuation gap 6 with a preset length is provided between the pre-polarizing magnet array 2 and the detecting magnet array 3. Therefore, the influence of the magnetic field generated by the pre-polarized magnet array on the magnetic field generated by the detection magnet array and the influence on the uniformity of the magnetic field in the detection area can be avoided. Such as: the magnetic field of the detection area detection magnet array may move towards the pre-polarized magnet array due to the influence of the magnetic field of the pre-polarized magnet array. A peak magnetic field is generated at the interaction of the pre-polarizing magnet array and the detecting magnet array, resulting in a gradient of the magnetic field in the detection region as a whole, such that the magnetic field of the detecting magnet array is no longer homogeneous. By providing a field strength decay distance between the pre-polarizing magnet array and the detecting magnet array, a valley in field strength can be created at the field strength decay distance, i.e., where the pre-polarizing magnet array and the detecting magnet array interact. Therefore, the influence of the magnetic field peak value generated at the interaction position of the pre-polarized magnet array and the detection magnet array on the magnetic field in the detection area is counteracted, the detection magnet array is ensured to generate a uniform magnetic field, and the accuracy of fluid detection of the nuclear magnetic resonance fluid analyzer is improved. The magnitude of the field intensity attenuation distance may be set according to actual needs, for example, may be determined by optimization design or simulation experiments, and the present application is not limited specifically.
Fig. 6 is a schematic three-dimensional structure of an nmr fluid analyzer according to an embodiment of the present invention, and as shown in fig. 6, the probe magnet array may include a plurality of segments of first ring magnet units, and the intervals between the segments of first ring magnet units may be different. As shown in fig. 6, in the detection magnet array region, each ring-shaped magnet structure may be referred to as a segment of the first ring-shaped magnet unit, and the intervals between the segments of the first ring-shaped magnet unit may be different. The specific numerical value of the distance between the first annular magnet units can be obtained by means of optimization design or simulation experiment and the like to achieve the maximum uniform magnetic field range as a target. The specific value of the spacing between the first ring magnet units is not particularly limited in this application. As shown in fig. 6, the probe magnet array in one embodiment of the present application may include 4 segments of the first ring magnet unit. The distances between the 4 segments of the first ring-shaped magnet units are sequentially called Gap3, Gap4 and Gap5, wherein the values of the distances can be: gap3 is 2mm, Gap4 is 10mm, and Gap5 is 1 mm. Each first ring magnet unit may include a plurality of octagonal magnet blocks.
As shown in fig. 6, in one embodiment of the present application, the pre-polarizing magnet array may include a plurality of segments of second ring-shaped magnet units, and the intervals between the segments of second ring-shaped magnet units are the same. In fig. 6, each ring-shaped magnet structure may be referred to as a segment of a second ring-shaped magnet unit in the pre-polarized magnet array region. The numerical value of the distance between the second annular magnet units may be set by using methods such as an optimization design or a simulation experiment, and the present application is not particularly limited. As shown in fig. 6, the pre-polarizing magnet array in one embodiment of the present application may include 7 second annular magnet units, a distance between each second annular magnet unit is referred to as Gap1, and a specific value of Gap1 may be Gap1 ═ 8 mm. Each second ring magnet unit may include a plurality of octagonal magnet blocks. The size and structure of the magnets in the second magnet unit and the first magnet unit may be the same or different, and the present application is not particularly limited.
The pre-polarizing magnet array and the detecting magnet array can both adopt a structure of a plurality of sections of magnet units, or one of the pre-polarizing magnet array and the detecting magnet array can adopt a structure of a plurality of sections of magnet units, and the other one of the pre-polarizing magnet array and the detecting magnet array can adopt other structures. For example: the pre-polarized magnet array is of an integral structure, and the detection magnet array is of a structure formed by splicing a plurality of sections of first magnet units.
As shown in fig. 6, a field strength attenuation distance is provided between the pre-polarizing magnet array and the detecting magnet array, and Gap2 indicates the field strength attenuation distance, and the field strength attenuation distance may be set to be Gap2 ═ 10mm in one embodiment of the present application, through an optimized design.
In one example of the present application, the structure and dimensions of the nmr fluid analyzer may be set as follows:
the inner diameter of the fluid pipe may be set to 32mm (1.25inch), the wall thickness may be set to 10mm, and the length may be set to about 1.5 m. The length of the pre-polarizing magnet array may be set to 573mm and the length of the detecting magnet array may be set to 312 mm. The pre-polarized magnet array of the single-ring Halbach structure may include 7 segments of second annular magnet units, and a spacing between each second annular magnet unit may be set to 8 mm. The detection magnet array of the double-ring Halbach structure may comprise 4 segments of the first ring magnet unit. The spacing between the 4 segments of the first ring magnet unit may be sequentially set as: 2mm, 10mm, 1 mm. Each segment of the first ring magnet units in the detection magnet array and each segment of the second ring magnet units in the pre-polarizing magnet array may include a plurality of octagonal magnet blocks. A field strength decay distance of about 10mm in length may be provided between the pre-polarizing magnet array and the detecting magnet array. A main antenna is arranged in a uniform magnetic field area generated by the detection magnet array, and an auxiliary antenna is arranged in a gradient magnetic field area generated by the detection magnet array. Meanwhile, a heat insulation layer can be arranged on the inner sides of the pre-polarized magnet array and the detection magnet array, and a temperature control system and a positive pressure unit are arranged on the magnets of the pre-polarized magnet array and the detection magnet array. The magnets in the pre-polarizing magnet array and the detecting magnet array may be samarium cobalt permanent magnets.
The structural size of the nuclear magnetic resonance fluid analyzer in each embodiment in the specification is only one embodiment, and in practical application, the numerical values of each size can be set as required.
Fig. 7 is a schematic diagram of the magnetic field distribution of the nmr fluid analyzer along the fluid direction in an embodiment of the application, and as shown in fig. 7, the pre-polarizing region is a region corresponding to the pre-polarizing magnet array, and the detecting region can be regarded as a region corresponding to the detecting magnet array. By adopting the structure of the nuclear magnetic resonance fluid analyzer of the embodiment, the central magnetic field intensity of the pre-polarization area is slightly higher than that of the detection area, so that the fluid can be rapidly polarized. And the field intensity attenuation distance is arranged between the pre-polarization magnet array and the detection magnet array, so that the magnetic fields of the pre-polarization area and the detection area can be in stable transition, and the detection area is ensured to have a section of uniform field intensity. And the detection magnet array adopts a double-ring Halbach structure, so that the magnetic field of a detection area is more uniform, and the accuracy and the signal-to-noise ratio of fluid detection are improved.
The application provides a nuclear magnetic resonance fluid analyzer, adopts the magnet outside, inside radiation magnetic field (the fluid pipeline is wrapped up to the magnet to inside radiation magnetic field) nuclear magnetic resonance fluid analyzer. The enclosed magnetic field structure can be additionally provided with the temperature control and positive pressure unit inside, so that adverse effects of external environment temperature, humidity, dust and the like on magnetic field intensity drift, erosion, electromagnetic interference and the like brought to the inside of the probe can be isolated, and the enclosed magnetic field structure has strong environmental adaptability and can be used in the field. In addition, the detection magnet array with the double-ring Halbach structure is adopted, a larger uniform magnetic field area can be obtained, and the detection precision and the signal to noise ratio are further improved. And the pre-polarized magnet array with the single-ring Halbach structure is arranged on the detection magnet array with the double-ring Halbach structure, the magnetic field intensity of the pre-polarized magnet array is slightly higher than that of the detection magnet array, so that the fluid can be quickly polarized, the fluid detection efficiency and accuracy are improved, and the maximum detection displacement is greatly increased. Meanwhile, the magnetic conduction shell with the magnetic field shielding effect is additionally arranged outside the magnet, so that the magnetic field intensity inside the nuclear magnetic resonance fluid analyzer can be shielded, and the magnetic leakage of the nuclear magnetic resonance fluid analyzer is avoided. For example, a magnetic conduction shell made of high magnetic conduction materials (such as silicon steel sheets) can be arranged to realize zero magnetic leakage outside the probe, and the safety of manual operation around the instrument is improved.
On the basis of the above embodiment, the present application also provides a method for manufacturing a nuclear magnetic resonance fluid analyzer, including: arranging a fluid pipe for flowing fluid, and sequentially and annularly arranging a pre-polarized magnet array and a detection magnet array on the radial outer side of the fluid pipe along the fluid flowing direction;
wherein, the detection magnet array adopts a double-ring Halbach structure.
An antenna may also be provided on the outer surface of the fluid tube in the region of the magnetic field generated by the array of detection magnets.
It should be noted that, in the present application, a specific manufacturing method of the preparation method of the nmr fluid analyzer may be performed by referring to an example of the structure of the nmr fluid analyzer, and details are not described here.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In the description of the specification, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the specification. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction. The drawings in the present specification are only schematic and do not represent actual structures of the respective components.
The above description is merely exemplary of one or more embodiments of the present disclosure and is not intended to limit the scope of one or more embodiments of the present disclosure. Various modifications and alterations to one or more embodiments described herein will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims.
Claims (12)
1. A nuclear magnetic resonance fluid analyzer, comprising: the fluid pipe is used for circulating fluid, a pre-polarized magnet array and a detection magnet array are sequentially and annularly arranged on the radial outer side of the fluid pipe along the fluid flowing direction, an antenna is arranged on the outer surface of the fluid pipe, and the antenna is arranged in a magnetic field area generated by the detection magnet array;
the detection magnet array adopts a double-ring Halbach structure;
the detection magnet array comprises a plurality of sections of first ring magnet units, the intervals between the first ring magnet units are different, so that a uniform magnetic field is generated near the middle area of the detection magnet array, and a gradient magnetic field is generated near the tail of the detection magnet array;
the pre-polarizing magnet array comprises a plurality of sections of second annular magnet units, and the intervals between the second annular magnet units are the same;
a main antenna is arranged in a uniform magnetic field area generated by the detection magnet array, and an auxiliary antenna is arranged in a gradient magnetic field area generated by the detection magnet array.
2. The nmr fluid analyzer of claim 1, wherein the probe magnet array comprises an inner ring comprising a plurality of octagonal first magnet segments and an outer ring comprising a plurality of octagonal second magnet segments.
3. The nmr fluid analyzer of claim 2, wherein the number of first magnet blocks and the number of second magnet blocks in the array of probe magnets are the same.
4. The nmr fluid analyzer of claim 1, wherein the pre-polarizing magnet array is of single-ring Halbach construction.
5. The nmr fluid analyzer of claim 1, wherein the pre-polarizing magnet array comprises a plurality of octagonal third magnet segments.
6. The nmr fluid analyzer of claim 1, wherein the central magnetic field strength of the pre-polarizing magnet array is greater than the central magnetic field strength of the probe magnet array.
7. The nmr fluid analyzer of claim 1, wherein the pre-polarizing magnet array and the detecting magnet array are separated by a field strength decay distance of a predetermined length.
8. The nmr fluid analyzer of claim 1, wherein the pre-polarizing magnet array and the probe magnet array are provided with a thermal barrier inside, the thermal barrier stabilizing the temperature within the pre-polarizing magnet array and the probe magnet array;
a temperature control system is arranged on the pre-polarizing magnet array and the detecting magnet array, and the temperature control system is used for controlling the temperature change in the pre-polarizing magnet array and the detecting magnet array.
9. The nmr fluid analyzer of claim 1, wherein the length of the pre-polarizing magnet array is greater than the length of the probe magnet array.
10. The nmr fluid analyzer of claim 1, wherein a magnetically permeable housing having a magnetic field shielding effect is disposed outside the pre-polarizing magnet array and the probe magnet array.
11. The nmr fluid analyzer of claim 1, wherein the magnet material in the pre-polarizing magnet array and the detector magnet array is samarium cobalt permanent magnets.
12. A preparation method of a nuclear magnetic resonance fluid analyzer is characterized in that a fluid pipe for flowing fluid is arranged, and a pre-polarized magnet array and a detection magnet array are sequentially and annularly arranged on the radial outer side of the fluid pipe along the fluid flowing direction;
the detection magnet array adopts a double-ring Halbach structure; a main antenna is arranged in a uniform magnetic field area generated by the detection magnet array, and an auxiliary antenna is arranged in a gradient magnetic field area generated by the detection magnet array;
the detection magnet array comprises a plurality of sections of first ring magnet units, the intervals between the first ring magnet units are different, so that a uniform magnetic field is generated near the middle area of the detection magnet array, and a gradient magnetic field is generated near the tail of the detection magnet array;
the pre-polarizing magnet array comprises a plurality of sections of second annular magnet units, and the intervals between the second annular magnet units of each section are the same.
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| CN109060861B (en) * | 2018-06-20 | 2021-06-29 | 张善文 | Permanent magnet device of nuclear magnetic resonance fluid metering instrument and metering method |
| CN109115821B (en) * | 2018-07-24 | 2021-09-24 | 张善文 | Nuclear magnetic resonance fluid meter probe and fluid metering method |
| CN108918573A (en) * | 2018-08-23 | 2018-11-30 | 中国石油天然气股份有限公司 | Oil-water two-phase flow component content measuring method and system |
| CN110579502B (en) * | 2019-09-29 | 2023-03-28 | 西安石油大学 | Sensor for nuclear magnetic resonance two-phase flow measurement |
| US11428557B2 (en) | 2020-08-31 | 2022-08-30 | Saudi Arabian Oil Company | Determining fluid properties |
| US11525723B2 (en) * | 2020-08-31 | 2022-12-13 | Saudi Arabian Oil Company | Determining fluid properties |
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| CN102444400A (en) * | 2011-11-15 | 2012-05-09 | 中国石油大学(北京) | Nuclear magnetic resonance fluid analyzer probe and nuclear magnetic resonance fluid analyzer |
| CN107064838A (en) * | 2017-04-25 | 2017-08-18 | 北京青檬艾柯科技有限公司 | It is a kind of to form the magnet system configurations and measuring method for becoming gradient magnetostatic field |
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| KR101287426B1 (en) * | 2011-10-26 | 2013-07-18 | 한국표준과학연구원 | Target Discrimination Method by using Ultra-Low Field NMR and Ultra-Low Field NMR Target Discrimination Apparatus |
| US10527565B2 (en) * | 2015-07-29 | 2020-01-07 | Chevron U.S.A. Inc. | NMR sensor for analyzing core or fluid samples from a subsurface formation |
| CN105201498B (en) * | 2015-09-23 | 2018-03-09 | 中国石油大学(北京) | Nuclear magnetic resonance downhole fluid analysis instrument |
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| CN102444400A (en) * | 2011-11-15 | 2012-05-09 | 中国石油大学(北京) | Nuclear magnetic resonance fluid analyzer probe and nuclear magnetic resonance fluid analyzer |
| CN107064838A (en) * | 2017-04-25 | 2017-08-18 | 北京青檬艾柯科技有限公司 | It is a kind of to form the magnet system configurations and measuring method for becoming gradient magnetostatic field |
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