31 results about "Relaxation (NMR)" patented technology

This application discloses a downhole nuclear magnetic resonance (NMR) inversion method, apparatus, equipment, and storage medium based on pruned Bayesian methods, relating to the field of NMR data processing technology. The method includes: constructing a forward dataset based on fluid relaxation time and acquisition parameters, and adding Gaussian white noise to obtain the inversion input signal; initializing prior parameters, posterior mean, and variance; constructing a kernel matrix based on relaxation time points; constructing a kernel-dictionary matrix using Gaussian functions; updating the fitted echo data and fitting residuals using hierarchical Bayesian methods, thereby updating the prior parameters; updating the posterior mean through evidence maximization and calculating the proportion of each fluid component; pruning the kernel-dictionary matrix according to a preset pruning threshold and proportion, iterating until a termination condition is met, and finally mapping to obtain a two-dimensional NMR relaxation spectrum. This method solves the problem of waiting time and loss of diffusion relaxation dimension information caused by improved logging efficiency, which makes accurate multidimensional NMR logging inversion difficult.

A traceable multi-mode extremely weak magnetic field measuring device and method, comprising helium-3 atoms and an atomic magnetometer in a spin-exchange relaxation-free state, the helium-3 atoms polarized by metastable exchange optical pumping under an extremely weak magnetic field provide a traceable magnetic field value for the atomic magnetometer, the value is compared with the output response of the atomic magnetometer to obtain a calibrated scale factor of the atomic magnetometer, so that the measurement values of the atomic magnetometer are traceable. The atomic magnetometer meter head comprises four independent detection channels, the four detection channels are obtained by beam splitting of two detection lasers with different frequency detuning amounts, and the channels have high consistency. The method proposed by the application is compatible with the cooperative use of multiple probes, and can realize single-meter-head multi-channel measurement, meter-head internal magnetic field gradient measurement and meter-head inter-magnetic field gradient measurement three measurement modes, each mode has high consistency and high sensitivity.

Methods and systems herein may perform nuclear magnetic resonance measurements, and nuclear magnetic resonance tools, the method and systems comprising: acquiring, using an NMR sensor a first NMR signal from a volume in a subterranean region, wherein the first NMR signal is acquired using a first acquisition window. Further, acquiring, using the NMR sensor a second NMR signal from a volume in the subterranean region, wherein the second NMR signal is acquired using a second acquisition window different from the first acquisition window, wherein the first NMR signal and the second NMR signal form an NMR relaxation data; determining, using the first NMR signal and the second NMR signal, a correction term. Finally, the correction term may be used to acquire a corrected relaxation data set.

The application discloses a method and device for determining oil saturation under reservoir conditions and a storage medium, and belongs to the technical field of oil and gas exploration and development. The method comprises the following steps: obtaining target micro-pore structure characteristics of a target well at a target depth, formation pore pressure, nuclear magnetic resonance logging T2 spectrum of the target well and a plurality of core samples; performing a dual-pressure nuclear magnetic joint measurement experiment on each core sample to construct a rock minimum connected pore diameter representation model; determining a rock minimum connected pore diameter according to the target micro-pore structure characteristics based on the rock minimum connected pore diameter representation model; determining a maximum capillary force according to the rock minimum connected pore diameter; determining an oil and gas charging minimum pore diameter according to the formation pore pressure, the maximum capillary force and the rock minimum connected pore diameter; determining a key relaxation time point according to the oil and gas charging minimum pore diameter; and determining the oil saturation according to the key relaxation time point and the nuclear magnetic resonance logging T2 spectrum. The application can improve the characterization accuracy of the oil saturation.

A detection method for detecting a detection target magnetic particle using an alternating excitation magnetic field includes: a step (S1) of acquiring, for a candidate magnetic particle, a Néel relaxation curve representing a relationship between a Néel relaxation time and a particle diameter; a step (S2) of acquiring, for the candidate magnetic particle, a Brownian relaxation curve representing a relationship between a Brownian relaxation time and the particle diameter; a step (S3) of determining, as an intersection point particle diameter, a particle diameter corresponding to an intersection point of the Néel relaxation curve and the Brownian relaxation curve; and a step (S4) of selecting, as the detection target magnetic particle, the candidate magnetic particle having a particle diameter larger than the intersection point particle diameter.

CPB images are acquired with pulsed exposures of fields of view (FOVs) defined in a region of interest of a sample. Multiple exposures are configured with a time interval greater than a phonon lifetime to reduce sample damage induced by the CPB exposure. FOVs can defined to be spaced apart to control effective irradiation dose based on a combination of direct exposure and evanescent exposure.

The application relates to a kind of ultra relaxation iteration prestack migration imaging methods based on thin plate approximation, first, the velocity model is divided into thin plates;In the first thin plate, the first-order ultra relaxation iteration solution G D (x,z,w) and the normal derivative B (x,z,w) of the first-order ultra relaxation iteration solution of reverse migration Green function are respectively solved by using source wavelet and prestack seismic record;The calculation result is used as the boundary condition of the next thin plate until the model bottom;G D (x,z,w) and B (x,z,w) are cross-correlated to obtain the final migration result.The application applies the method for solving scattering wave field by using ultra relaxation iteration solution to wave field continuation of prestack migration, overcomes the problem that the traditional Born scattering series is limited by weak scattering assumption and is only suitable for short-range propagation;The model is divided by referring to the thin plate approximation idea, the global relaxation factor is converted into local relaxation factor, the storage space is reduced, the calculation efficiency is improved without affecting the precision;The migration precision is improved.

A triple-tuned radio frequency coil transceiver system and a nuclear magnetic resonance imaging device. The triple-tuned radio frequency coil transceiver system comprises a coil circuit, a first transceiver link, a second transceiver link, and a first signal filter. The first signal filter comprises a first filter and a second filter. The passband range of the first filter does not coincide with the passband range of the second filter. A first end of the first filter and a first end of the second filter are both electrically connected to the coil circuit. A second end of the first filter is electrically connected to the first transceiver link, and a second end of the second filter is electrically connected to the second transceiver link. The first transceiver link is configured to transmit and receive a first nuclide signal. The second transceiver link is configured to transmit and receive a second nuclide signal and a third nuclide signal. The coil circuit is configured to generate relaxation signals of a first nuclide, a second nuclide, and a third nuclide.

The application discloses an interface reaction kinetics parameter analysis method based on electrochemical impedance spectroscopy, and relates to the technical fields of electrochemical testing and data processing, and comprises the following steps: applying an alternating current signal with gradually increased amplitude to a to-be-tested interface, and extracting a fundamental frequency impedance vector and a harmonic impedance vector; performing anti-convolution calculation on the fundamental frequency impedance vector and the harmonic impedance vector respectively by using preset standard penalty weights, obtaining a fundamental frequency relaxation vector and a harmonic relaxation vector, and dividing the amplitudes of the two vectors by a node to obtain a response ratio; identifying an aliasing peak interval with an information entropy greater than an entropy value determination threshold in the fundamental frequency relaxation vector, wherein the aliasing peak interval contains an aliasing peak, and the aliasing peak only overlaps with an extreme value point of the response ratio; and the method has the beneficial effect that the evaluation error caused by improper selection of a human prior model is reduced, and the reliability of interface kinetics parameter analysis is ensured.

The present disclosure discloses a radio frequency antenna, a magnetic resonance imaging system, and a scan control method thereof. The radio frequency antenna for the magnetic resonance imaging system comprises: a first coil assembly including a first device for transmitting radio frequency excitation signals and a second device for receiving magnetic resonance relaxation signals of first nuclei; and a second coil assembly including a third device for receiving magnetic resonance relaxation signals of second nuclei different from the first nuclei; the first coil assembly and the second coil assembly being disposed on a support structure.

This invention discloses a method and system for quantitative analysis of the full-scale microstructure of chloride-containing silty clay, belonging to the field of geotechnical materials mechanics. The method first prepares standard samples and performs CT and NMR tests to obtain microscopic two-dimensional images and microscopic relaxation time distributions. Micrometer-level pore characteristic parameters are extracted based on image processing, and nanometer-level pore characteristic parameters are inverted based on the relaxation mechanism. The two types of parameters are compared and fused, and overlapping data are corrected to generate a full-scale pore size distribution curve covering the nanometer to micrometer scales. The pore size fractal dimension is then calculated through piecewise fitting. This invention integrates the complementary advantages of CT and NMR technologies, overcoming the limitations of single-scale analysis, and achieving integrated, full-scale characterization of the microstructure of saline soils, providing a reliable tool for revealing the evolution mechanism of their macroscopic mechanical properties.

A system of field cycled magnetic resonance system and a method of operating a field cycled magnetic resonance system are described. In accordance with various embodiments, the disclosed system includes a static field magnet, wherein the magnet is configured to provide a low static external magnetic field to a given field of view, a radio frequency coil, and a field cycling magnet. In accordance with various embodiments, the method includes providing a static field magnet configured to image a tissue sample within a given field of view, applying a low static external magnetic field to the given field of view, providing a radio frequency coil configured to produce cycling radio frequency field, providing a field cycling magnet, altering the low static external magnetic field within the given field of view, and collecting images from the system.

The invention relates to the field of dairy product foam moisture migration and stability correlation analysis, in particular to a dairy product foam moisture migration and stability correlation analysis method. The method comprises the following steps: firstly, based on an obtained dairy product foam sample, acquiring a relaxation signal, performing normalization processing to obtain a nuclear magnetic resonance signal sequence, introducing a signal smooth extension method to obtain a nuclear magnetic energy density function, and further constructing a composite nonlinear enhancement function; then, based on the composite nonlinear enhancement function, constructing a migration gradient response function; obtaining a migration probability based on the migration gradient response function; calculating a moisture migration entropy weight index based on the migration probability; and finally, based on the moisture migration entropy weight index, obtaining a foam structure stability estimated value, and obtaining an analysis result. The technical problems of non-destructive, quantitative and dynamic identification of internal moisture migration behaviors and establishment of a mathematical mapping relation with physical interpretation force for moisture migration characteristics and foam structure stability are solved.

This invention discloses an NMR system for large-scale geodensity detection, comprising a computer that controls a radio frequency transmitter to emit radio frequency signals. These signals are amplified by a radio frequency power amplifier and then distributed and transmitted to the main probe via a power divider. The main probe and secondary probes receive NMR relaxation signals in parallel and transmit them to the computer. The permanent magnets of each probe in the probe group can rotate along their own axes. This invention also discloses an NMR detection method for large-scale geodensity detection, which involves determining the number n of probes in the probe group and their positions; identifying and classifying target detection areas based on their positions; measuring the geodensity of each target detection area and summing the results to obtain the total geodensity of the detection area. This invention achieves large-scale density detection by cooperating with multiple probes to measure multiple target detection areas.

The application discloses a coal reservoir pore dynamic quantitative characterization method based on low-field nuclear magnetic resonance, and belongs to the technical field of coal reservoir detection. T 2The relaxation time difference accurately distinguishes the adsorbed state and the free state of methane, establishes the quantitative correlation of nuclear magnetic resonance signals and pore parameters, and directly obtains the adsorption-induced pore strain and reservoir pore compressibility.The application does not need to rely on indirect parameters such as elastic modulus, realizes the non-invasive and real-time quantitative characterization of the dynamic evolution of the pore volume of the coal reservoir, and the test result is accurate and reliable, thereby providing key parameters for the permeability prediction of coalbed methane exploitation and gas extraction.

The present disclosure relates to a magnetic resonance diffusion imaging fat suppression method based on echo navigation water-fat separation, comprising: acquiring echo and / or navigation echo corresponding to multiple chemical shift encoding points under the condition that the b value is equal to 0 and the condition that the b value is greater than 0; solving the water map, the fat map, the main magnetic field inhomogeneity and the relaxation time of the target object under the condition that the b value is equal to 0, and determining the water map and the fat map of the target object under the condition that the b value is greater than 0. Through the present disclosure, a chemical shift encoding fat suppression method suitable for clinical use is provided for magnetic resonance EPI diffusion imaging, the interference of fat chemical shift artifacts is reduced, the accuracy of image contrast and quantitative parameter measurement is improved, the universality of chemical shift encoding EPI DWI is improved, and the image reconstruction speed and robustness are accelerated.

The invention discloses a rock CT pore structure evaluation method based on nuclear magnetic resonance measurement, and the method comprises the steps: obtaining a three-dimensional space imaging result of a shale oil rock sample through the CT scanning of a rock core, obtaining the porosity of the shale rock core through the nuclear magnetic resonance technology, and obtaining the porosity of the shale rock core through the corresponding relation between the nuclear magnetic porosity and the porosity of the shale rock core CT data. Taking the porosity of the nuclear magnetic resonance T2 spectrum relaxation component and an accumulated pore curve as a basis, selecting a segmentation threshold value of rock core CT data, extracting a three-dimensional structure of pores in the shale core to obtain a pore structure of the rock core, and counting pore size distribution of the pore structure through an equivalent diameter method to obtain a pore size distribution curve of the rock core. The problems that the three-dimensional pore structure of the reservoir rock sample cannot be intuitively represented and the isolation, connectivity and spatiality of pores in the rock core cannot be intuitively and accurately described in the conventional nuclear magnetic resonance measurement are solved.

This invention discloses a method, apparatus, device, and storage medium for determining shale relaxation time, comprising: simulating a pre-defined molecular simulation model in a pre-set experimental simulation environment to obtain the inter-pair distance and inter-pair angle of hydrogen proton pairs in the molecular simulation model; obtaining the residual dipole coupling relaxation time based on the inter-pair distance and inter-pair angle; and obtaining the transverse relaxation time based on the residual dipole coupling relaxation time and the theoretical relaxation time. The shale relaxation time determination method, apparatus, device, and storage medium disclosed in this application solve the problem of uncertainty or significant mismatch between the pore size distribution derived from the transverse relaxation time based on NMR theory and the actual pore size distribution. This allows for a more accurate reflection of the actual pore size distribution through the calculation of the residual dipole coupling relaxation time under nano-constraint effects, thereby ensuring the accuracy of shale oil reservoir evaluation.

The application discloses a movable oil saturation determination and calculation model establishment method and device, which comprises the following steps: performing nuclear magnetic resonance measurement on cores in different saturation states in a target exploration area to obtain two-dimensional nuclear magnetic resonance spectra and one-dimensional nuclear magnetic resonance spectra of the cores at each measurement position, determining fluid types and positions on the two-dimensional nuclear magnetic resonance spectra, and the fluid types include movable oil; mapping movable oil positions on the two-dimensional nuclear magnetic resonance spectra and the one-dimensional nuclear magnetic resonance spectra to determine relaxation times of the movable oil; determining movable oil saturation under nuclear magnetic logging based on the relaxation times of the movable oil; and establishing a movable oil saturation calculation model of conventional logging according to the movable oil saturation under the nuclear magnetic logging, formation resistivity at each measurement position and formation porosity, which is used for determining movable oil saturation of a shale oil reservoir, wherein the formation resistivity and the formation porosity are extracted based on conventional logging data. The method can improve the accuracy of movable oil saturation calculation of conventional logging.

This invention provides a calibration system and method for a spin-free exchange-relaxation atomic magnetometer, belonging to the field of precision measurement technology. The calibration system includes: a magnetic field coil configured to generate a square-wave alternating magnetic field within a preset frequency range; an atomic gas chamber configured to provide a polarizable atomic medium, wherein, when the spin-free exchange-relaxation atomic magnetometer is in an unshielded state, the atomic medium undergoes Larmor precession under the influence of the square-wave alternating magnetic field to modulate the probe light of the spin-free exchange-relaxation atomic magnetometer, obtaining an optical modulation signal; a photodetector configured to convert the optical modulation signal into an electrical signal, wherein the electrical signal is used to characterize the amplitude-frequency characteristics corresponding to the frequency range; and a calibration module configured to perform peak detection on the electrical signal and determine the operating state of the spin-free exchange-relaxation atomic magnetometer based on the peak detection result.

The disclosed systems and methods use the developed Flexible Relaxation and Saturation Time (FIRST) approach to provide customization of parameters for a Magnetization Transfer (MT) sequences to maximize sensitivity and efficiency. The methods may include generating one or more customized parameters for one or more iterations of a Magnetization Transfer Magnetic Resonance (MR) sequence that is executed on a Magnetic Resonance Imaging (MRI) System. The generating may include receiving input parameters for each iteration of the sequence. The one or more input parameters may include radiofrequency (RF) offset and / or saturation power. The generating may further include determining a set of one or more customized parameters for each iteration using the input parameters for each RF offset and / or saturation power. The one or more customized parameters may include repetition time (TR).

This invention discloses a method for identifying water inflow channels based on nuclear magnetic resonance (NMR) and ground-to-air electromagnetic (GTEM) fusion, applicable to the fields of geophysical exploration and hydrogeology. It addresses the problems of multiple solutions and insufficient accuracy when using single geophysical methods to identify water inflow channels. Specifically, this invention targets open-pit coal mine exploration areas, simultaneously implementing GTEM scanning, NMR measurement points, and flow field profiling to acquire multi-source geophysical data. A three-dimensional integrated geological model incorporating resistivity, water content, and hydraulic conductivity parameters is constructed. Based on an inversion framework of coupled electromagnetic induction, NMR relaxation, and seepage mechanisms, a synergistic inversion is performed to generate a multi-parameter fused attribute volume. Furthermore, hydrogeological feature definitions and machine learning spatial pattern recognition are used to automatically delineate suspected water inflow channels. Finally, by optimizing the layout of verification boreholes and dynamically correcting the model and identification patterns using measured data, high-precision, high-efficiency integrated identification and three-dimensional visualization of water inflow channels are achieved.

Disclosed are a method and apparatus for providing repeated exposure of a sample area to a charged particle beam (CPB) such that effective exposure is controlled to avoid or reduce sample damage caused by the CPB. [Solution] CPB images are acquired using pulsed exposures to a defined field of view (FOV) within the region of interest of the sample. Multiple exposures are performed at time intervals longer than the phonon lifetime to reduce sample damage induced by CPB exposure. The FOV can be defined to be spaced apart in order to control the effective radiation dose based on a combination of direct and evanescent exposures.

The application belongs to the technical field of amorphous nanocrystalline soft magnetic material and its preparation, and particularly relates to an amorphous nanocrystalline soft magnetic alloy with high saturation magnetic induction and low coercivity and a preparation method thereof. a B b Si c Cu d Q e (M is Fe, or M includes at least one of Co and Ni and Fe, and the atomic percentage content of Fe in M is greater than or equal to 75%; Q is at least one of C, P and Cr). The alloy contains at least one of an alpha-Fe nanophase or a crystal nucleus or a ferromagnetic atomic cluster with a size less than 20 nm in a quenched state. Different from a preparation method of a traditional nanocrystalline soft magnetic alloy, which needs to prepare an amorphous alloy first and then perform crystallization annealing above a first starting crystallization temperature, the amorphous alloy in the application does not need to be crystallized by annealing, but only needs to be stress-relieved annealed (also known as relaxation annealing) at 50-120 DEG C below the first starting crystallization temperature, and the saturation magnetic induction of the alloy can reach 1.71-1.97 T, and the coercivity is as low as 1.0-7.0 A / m. By optimizing the alloy composition ratio and the heat treatment process, the application realizes a good balance between high magnetic induction and low coercivity, and the alloy is suitable for manufacturing high-frequency transformers, inductors and other power electronic devices.

The present invention provides a release film which is excellent in both release property and following property to unevenness and in which resin bleeding is less likely to occur. The present invention is a release film in which the relaxation time (T2) of a soft component at 180°C measured by CPMG method using pulse NMR is 220 msec or more and 330 msec or less, and in which the ratio of a soft component at 30°C measured by Solid Echo method using pulse NMR after exposure to the following temperature condition is 0.1% or more and 15% or less. Temperature condition: temperature is raised from 30°C to 180°C at a rate of 10°C / min, and then, temperature is lowered from 180°C to 30°C at a rate of 10°C / min.