333 results about "Low field nuclear magnetic resonance" patented technology

A nuclear magnetic resonance sensing apparatus and method for operating in an earth borehole comprises a source of switchable magnetic field to polarize nuclei in the region of interest, said source comprising a coil wound on a magnetic core having controllable residual magnetization. Maintaining the magnetization of the core during a polarization interval does not require steady current in the coil. Switching intensity and polarity of magnetization of the core causes precession of spin magnetic moments of the nuclei; the precession induces a signal indicative of nuclear magnetic resonance properties of earth formations.

A laboratory NMR methodology (and corresponding laboratory apparatus) defines a sample volume. The method stores downhole tool data corresponding to a hydrocarbon-bearing sample collected from a given subsurface formation. The downhole tool data includes parameters pertaining to magnetic fields used by a downhole tool during a suite of NMR measurements of the given subsurface formation. The sample is positioned in the sample volume of the laboratory apparatus, which applies a static magnetic field in the sample volume. Furthermore, the laboratory apparatus applies a suite of NMR measurements to the sample volume to thereby determine a property of the sample. The NMR measurements of the suite each include a pulse sequence of oscillating magnetic field in conjunction with a pulsed-mode gradient field. The pulsed-mode gradient field is based on the stored downhole tool data corresponding to the sample. A laboratory NMR methodology for optimizing downhole NMR measurements is also described.

The invention discloses a method for accurately measuring shale porosity by adopting the low-field nuclear magnetic resonance. The method comprises the following steps: as for a saturated water column-shaped shale sample, conducting nuclear magnetic porosity measurement in different echo time and waiting time; conducting helium porosity measurement; comprehensively comparing and analyzing the porosity results of the two methods; optimizing the optimal echo time and waiting time for testing to facilitate the accurate testing of follow-up samples. The method solves the problems of how to set reasonable parameters to measure the shale porosity by adopting the low-field nuclear magnetic resonance, and solves the problem that in the actual testing, the nuclear magnetic porosity obtained in different echo time and waiting time is in great disparity, and the comparability of the nuclear magnetic porosity and the helium porosity is relatively poor; compared with the prior art, by adopting the method, the shale porosity can be quickly and nondestructively measured, the accuracy and precision of the shale porosity measurement can be improved, and the operation is convenient.

An ultra-low magnetic field NMR system can non-invasively examine containers. Database matching techniques can then identify hazardous materials within the containers. Ultra-low field NMR systems are ideal for this purpose because they do not require large powerful magnets and because they can examine materials enclosed in conductive shells such as lead shells. The NMR examination technique can be combined with ultra-low field NMR imaging, where an NMR image is obtained and analyzed to identify target volumes. Spatial sensitivity encoding can also be used to identify target volumes. After the target volumes are identified the NMR measurement technique can be used to identify their contents.

The present invention relates to a device capable of producing a high resolution chemical analysis of a sample, such as fluid, based upon nuclear magnetic resonance (NMR) spectroscopy, where the nuclear magnetic polarizations of the sample are generated by sequentially illuminating the sample with a focused beam of light carrying angular orbital angular momentum (OAM) and possibly momentum (spin). Unlike in usual NMR used for magnetic nuclear resonance imaging (MRI) or spectroscopy, the invention does not make use of a strong magnet.

The invention discloses a method for identifying the quality of edible oil with low-field NMR (Nuclear Magnetic Resonance), suitable for identifying and measuring genuine edible oil and inferior drainage oil. The method rapidly and accurately identifies the genuine edible oil and the inferior drainage oil by using the difference between the relaxation time map data of the genuine edible oil and the inferior drainage oil as a main identification reference, using NMR signals of the genuine edible oil and the inferior drainage oil as main observation objects and using the comparison and the analysis of the transversal relaxation time map data of the genuine edible oil and the inferior drainage oil as main measures. The method of the invention has high measuring result accuracy, good repetition and stability, short duration, and the like, is beneficial to the realization of the one-site identification of the qualities of various kinds of edible oil and provides reliable oil quality information for detecting the qualities of various kinds of edible oil.

The invention discloses a method for measuring the oil content of drilling fluid through low-field NMR (Nuclear Magnetic Resonance), suitable for measuring the content of crude oil with different densities in the drilling fluid. The method comprises the step of measuring the oil content of the drilling fluid by using the transverse relaxation time of the crude oil and the drilling fluid and different diffusion coefficients as main identification criteria, using the signal strength of NMR of the crude oil and the drilling fluid as a main observation object and using the transverse relaxation analysis of the drilling fluid and the correlation analysis of the diffusion coefficients and transverse relaxation as main measures. The method of the invention has the advantages of high measuring result accuracy, good stability, short time consumption, and the like, is easy to realize the online measurement of the oil content of the drilling fluid and provides reliable storage information of an oil layer for logging operation.

The invention discloses a method for measuring coal sample methane adsorbing capacity through low-field nuclear magnetic resonance. According to the method, selected measuring parameters are used for carrying out low-field nuclear magnetic resonance measurement on powder coal samples after methane adsorption balance under set pressure, the nuclear magnetism T2 spectrum of methane in the coal samples is obtained, then signal amplitude integrals of the first spectrum peak (in the range of 0.1-4ms spectrum) on the left of the T2 spectrum are substituted to a hydrogen content index reticle equation of methane under the standard condition built through an experiment, the standard condition size of methane adsorbed by the coal samples is obtained, and therefore the methane adsorbing capacity of unit mass of coal under the set pressure is obtained. According to the method, the scale relation of methane mass and nuclear magnetic resonance 1H nuclear signals is built, the quantitative assay of methane adsorbing capacity under the same temperature and different pressures is achieved, and the novel method can be used for measuring coal methane absorbing capacity in a real-time, home-position and dynamic mode.

The invention discloses a quick measurement method for different forms of water in sludge. The quick measurement method comprises the following steps of: (1) performing low-field nuclear magnetic resonance measurement on the sludge to obtain a transverse relaxation time T2 spectrum of different forms of water in the sludge; (2) stewing and settling activated sludge, preparing a standard sample by supernatant liquid at equal mass interval, and constructing a standard curve; (3) according to the obtained standard curve, matrixing the low-field nuclear magnetic resonance transverse relaxation time of the sludge to obtain three different forms of water, namely free water mass, interstitial water mass and surface combined water mass in the sludge; and (4) drying the sludge to be measured until the weight is balanced, subtracting the final mass from the initial mass, and calculating the fourth form of water in the sludge, namely the internal combined water mass. Compared with the conventional method, the quick measurement method for measuring the content of different forms of water in the sludge by a nuclear magnetic resonance technology has the advantages of short experiment time, harmlessness to experiment samples, precision of measurement and the like.

A Nuclear Magnetic Resonance (NMR) apparatus and method for measuring the water content of samples has a device to produce a main magnetic field; a sample receiving space within a main magnetic field; a device to excite a measurable RF magnetization to a sample placed into the sample receiving space at an operating frequency defined by the main magnetic field; a device to measure the RF signal produced by the excited sample; and a device to determine the water content in the sample based on the RF signal. The sample receiving space is capable of accommodating a sample having a volume of at least 0.5 dm³, and the device to produce a main magnetic field has a resistive electromagnet which is adapted to produce a main magnetic field corresponding to an operating frequency of 400-2000 kHz.

An ultra-low field (ULF) nuclear magnetic resonance (NMR) and/or magnetic resonance imaging (MRI) system can be used for rapid identification and discrimination of materials, e.g., liquid in opaque containers and/or materials in or on human bodies. The system utilizes the ability of ULF NMR/MRI to measure NMR parameters in magnetic fields that can be easily changed in field strength and orientation.

The invention provides a method for true and false identification and content determination of sesame oil. The method utilizes a low-field nuclear magnetic resonance technique to identify and determine the content of the sesame oil. The method mainly comprises the operation steps that 1, a mixed oil sample is prepared; 2, a detection sample is prepared; 3, relaxation signals of pure sesame oil, pure soybean oil and mixed oil are quickly determined by the low-field nuclear magnetic resonance technique; and 4, signal data is analyzed and processed. The method is easy and simple to operate and good in effect, can achieve quick detection of the content of the sesame oil in the sesame oil and soybean oil mixed sample, is applicable to the field of quality control of the pure sesame oil, and lays a foundation for quality detection work of the sesame oil.

The invention discloses a low field nuclear magnetic resonance probe based on a printed circuit board helmholtz coil. A PCB substrate is taken as a substrate. An upper surface of the PCB substrate is provided with a first bonding pad, a second bonding pad, an upper portion lead wire and an upper portion plane coil. A lower surface of the PCB substrate is provided with a lower portion lead wire and a lower portion plane coil. An outer end of the upper portion plane coil is connected with the first bonding pad through the upper portion lead wire. An outer end of the lower portion plane coil is connected with the lower portion lead wire. An inner end of the upper portion plane coil and an inner end of the lower portion plane coil are connected through a first metalized through hole. The second bonding pad and the lower portion lead wire are connected through a second metalized through hole. A central section of the PCB substrate is provided with a sample through hole which passes through up and down. The nuclear magnetic resonance probe based on PCB helmholtz coil provided in the invention adopts a PCB technology and possesses the following advantages that manufacturing is simple; cost is low; a period is short; mass production can be realized and so on. And a radio-frequency field which is relatively uniform can be generated.

The invention belongs to the field of building materials, and particularly relates to a method for rapidly and continuously representing cement hydration degrees by means of a low-field nuclear magnetic resonance technology. The method comprises the following steps that 1, slurry is prepared, weighing is conducted, the water content m<0> and the cement content m<c> in the cement slurry are calculated, the slurry is rapidly put in a low-field nuclear magnetic resonance instrument, and test is conducted after system parameters and sampling interval time are set; 2, a CPMG impulse sequence is adopted to collect nuclear magnetic resonance transverse relaxation decay signals at t moments in different hydration time; 3, first echo peak amplitudes I(t) of a decay curve at the t moments in the different hydration time are automatically collected, and an amplitude I<0> of a first collection point is recorded; 4, physical combined water amounts m(t) at the hydration t moments are determined through the specific value of the I(t) to the I<0>, and hydration degrees alpha(t) at the hydration t moments are obtained according to the formula in the specification; 5, a relation curve of the alpha(t) and t is drawn, and the hydration degrees at any hydration t moment can be read. According to the method for rapidly and continuously representing the cement hydration degrees by means of the low-field nuclear magnetic resonance technology, drying or stopping of hydration to samples is not needed, and in-situ detection and continuous monitoring to the cement hydration degrees can be achieved.

Provided are an object discrimination method and an object discrimination apparatus using an ultra-low magnetic field nuclear magnetic resonance (NMR). The method includes measuring the respective spin-lattice relaxation times at a plurality of strengths of prepolarization magnetic fields with respect to a measurement target and classifying the measurement target using the spin-lattice relaxation times.

The invention discloses a movable low-field nuclear magnetic resonance imaging system which comprises a movable spectrometer, a magnet, a computer, a radio frequency amplifier, a gradient power amplifier and a coil, as well as a movable magnet frame, wherein the magnet is a rotatable low-field magnet arranged on the movable magnet frame, and a shield is embedded in the low-field magnet. The movable low-field nuclear magnetic resonance imaging system combines the low-field magnet with the movable magnet frame, has small equipment volume and light weight and can carry out fast and timely medical examination in emergencies, rescue scenes, playgrounds, countrysides and other special occasions without being limited by time and place; the low-field magnet can realize omni-directional rotation on the magnet frame, adjust the height of a magnetic field according to needs, carry out accurate examination and diagnosis on a patient in any posture and body position and further reduce the motion of the patient; the adoption of the low magnetic permanent magnet has low maintenance cost and low cost and reduce the production cost; and the movable low-field nuclear magnetic resonance imaging system has good openness, can not cause the oppression to the patient, is applicable to local examination or interventional therapy of the head, the limbs and the like, and is particularly applicable to thorough examination of infants.

The invention provides a method for detecting the water content and fat content in abalone through a low-field nuclear magnetic resonance technology. The method comprises the following first step of collecting samples, the second step of carrying out low-field nuclear magnetic analysis on the sample, the third step of measuring the samples, the fourth step of establishing a model, the fifth step of evaluating the model, and the sixth step of measuring the water content and the fat content of the samples to be detected. By means of the method, the water content and fat content in abalone can be measured at the same time, detection is rapid and accurate and free of the influence of the surface feature of abalone, and abalone is not damaged in the measuring process.

The invention provides a method for nondestructive detection of water and fat contents of yellow croaker. The method comprises 1, yellow croaker sample detection: acquiring a transverse relaxation signal through a CPMG sequence so that a yellow croaker sample transverse relaxation spectrum is obtained, 2, determination of yellow croaker water and fat contents, 3, building of yellow croaker water and fat content prediction models: building prediction models through the T2 relaxation spectrum as an independent variable and water and fast contents as dependent variables, and 4, signal data analysis and processing. The method researches correlation of the spectrum and ingredients, utilizes yellow croaker low field nuclear magnetic resonance relaxation data as a research object and yellow croaker water and fast contents as indexes to build the yellow croaker water and fat content PCR and PLSR prediction models and realizes fast detection of water and fat contents of the yellow croaker.