271 results about "Solid-state nuclear magnetic resonance" patented technology

The invention provides nuclear magnetic resonance equipment realizing improved sensitivity of a probe for receiving a free induction decay (FID) signal in nuclear magnetic resonance (NMR) spectroscopy in a high frequency band of 600 MHz or higher. By manufacturing a solenoid coil of a higher filling factor by using a superconductor of extremely low resistance to high frequency current, sensitivity is increased. A superconducting thin film made of magnesium diboride (MgB₂) formed on a donut plate-type substrate is disposed so that the film surface becomes parallel with the uniform magnetic field. The object is realized by a probe made by a solenoid coil formed by connecting a plurality of coil parts by capacitive coupling via a normal metal lead.

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 relates to a rock core holder compatible with nuclear magnetic resonance, which can simulate pressures and temperatures of deep reservoirs, perform oil water displacement of a rock core under simulated formation conditions, and simultaneously perform nuclear magnetic resonance on-line measurement. According to the invention, a radio frequency coil is embedded in the rock core holder, and the signal to noise ratio is greatly increased when the rock core holder is compared with a conventional rock core holder. The rock core holder is made of nonmagnetic nonmetal materials, which avoids the damage of the magnetic field uniformity caused by magnetic materials, and also avoids the generation of eddy current in the holder by a pulse gradient. Compared with a conventional rock core holder, the invention not only greatly increases the signal to noise ratio, but also fully ensures the accuracy of nuclear magnetic resonance measurement results at a high temperature and a high pressure. The holder is applicable to on-line measurement of nuclear magnetic resonance relaxation spectra, diffusion-relaxation two-dimensional spectra, and imaging methods during rock core oil water displacement at a high temperature and a high pressure. In addition, the invention performs real-time tracking compensation of temperatures and pressures of ring-crush fluid, and thus ensures the reliability of rock core simulated formation conditions.

Silica with a large pore volume, a large specific surface area, a narrow pore distribution, low contents of unwanted metal impurities, and excellent physical properties such as high heat-resistance and water-resistance is provided. The silica has a mode pore diameter (D_max) of 20 nm or less, and a solid-state Si nuclear magnetic resonance (hereinafter called solid-state Si NMR) spectrum of the silica includes a chemical shift (δ ppm) of Q⁴ peak meeting the following inequality (I).

−0.0705×(D_max)−110.36>δ  (I)

The silica with such properties can be suitably used in fields of which particularly excellent heat resistance and water resistance are required, and moreover controlled pore properties, and the fact that physical properties scarcely change over a long period of time are required among the above-mentioned applications.

The invention relates to an inversion method of nuclear magnetic resonance two-dimensional spectrum. The method includes firstly, extracting and estimating noise, namely extracting noise in CPMG (Carr-Purcell-Meiboom-Gill) echo string of acquired data and estimating standard deviation of the noise; secondly, compressing data, namely generating an inversion kernel and performing truncated singular value decomposition and reconstruction by sequence of a nuclear matrix to complete data compression; and thirdly, fitting the data, namely subjecting fitting problem of the compressed data to regularization, performing iterative solution to regularization factors and inversion spectrum by newton method with non-exact one-dimensional search so as to obtain the inversion spectrum. Execution efficiency of two-dimensional inversion algorithm and resolution of two-dimensional spectrum are increased greatly, and the inversion method is well robust.

The invention discloses a geophysical exploration device and the method which combines the nuclear magnetic resonance and the transient electromagnetism. First to select the coupled device in the transient electromagnetism mode, and it lays the emission loop and the receiving loop to detect every measuring point in the detecting section and treat the transient electromagnetism data to find the low electrical resistivity point; then it changes to the nuclear magnetic resonance mode and lays the emission loop using the demarcated abnormal detecting point as the center, so it compares the detected data or the figure with the resistivity detected by the transient electromagnetism to judge the true or false of the detected resistivity. The invention can decrease the device cost and improve the detecting efficient and the precision.

The present invention has an object to provide a nuclear magnetic resonance imaging apparatus or the like that avoids a region with zero sensitivity of an optical magnetometer and allows imaging by strong magnetic resonance when a common magnetic field is used as a bias field of an optical magnetometer and as a magnetostatic field to be applied to a sample. When a direction of a magnetostatic field application unit applying a magnetostatic field to a sample is a z direction, alkali metal cell of a scalar magnetometer is arranged so as not to overlap a region to be imaged in a z direction, and so as not to intersect the region to be imaged in an in-plane direction perpendicular to the z direction.

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.

The invention relates to an on-line testing device for high temperature and high pressure rock physical property and percolation mechanism nuclear magnetic resonance. The on-line testing device comprises a nuclear magnetic resonance on-line testing module, a rock fluid displacement module (comprising core holder compatible with nuclear magnetic resonance tests) and a computer control and data processing module, a nuclear magnetic resonance testing system and a rock fluid displacement system are combined into a whole through computer control, formation temperature and pressure are simulated, rock displacement tests are carried out under high temperature and high pressure conditions, and real-time nuclear magnetic resonance signals are measured on line to obtain rich rock parameters (porosity, permeability, reservoir forming critical pressure, wettability and the like). The on-line testing device serves as a device for oil gas reservoir forming geological research and oil gas target assessment, and the purposes of analyzing core physical properties and percolation mechanism from micro perspective are achieved.

The invention discloses a shale gas reservoir pore structure quantitative calculation method based on nuclear magnetic resonance. The shale gas reservoir pore structure quantitative calculation methodcomprises the following steps: collecting cores; drilling parallel samples, carrying out oil and water self-adsorption nuclear magnetic resonance experiment measurement; contrastively analyzing the difference of a parallel sample oil and water nuclear magnetic resonance T2 spectrum, and determining the distribution of different wetting pore types on the nuclear magnetic resonance T2 spectrum; obtaining a shale gas reservoir full-pore distribution curve according to high-pressure pressurized mercury, nitrogen adsorption and carbon dioxide adsorption; furthermore, obtaining an intersection plate of pore diameters and corresponding T2 time; and according to the intersection plate of different pore types of pore diameters and corresponding T2 time, establishing a quantitative calculation model of the pore diameters according to the pore types. The method has the advantages that a shale gas reservoir pore full-pore distribution curve can be quantitatively calculated through the technology;simultaneously, the nuclear magnetism measurement is quick, simple and loss-free, and is higher in practicability by compared with high-pressure pressurized mercury, nitrogen adsorption and carbon dioxide adsorption; and compared with a conventional method, the calculation result is more accurate.

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 invention discloses a method for obtaining nuclear magnetic resonance two-dimensional J-resolved spectroscopy in a non-uniform magnetic field, and relates to a nuclear magnetic resonance spectrometer. The method comprises the steps that a piece of one-dimensional spectroscopy is sampled through a general one-dimensional pulse sequence, the line width of a spectral line is obtained, the basis is provided for spectral width parameter setting, and the line width reflects the magnetic field environment uniformity condition; (2) an intermolecular single-quantum coherent two-dimensional J-resolved spectroscopy pulse sequence which is compiled in advance is led to the nuclear magnetic resonance spectrometer; (3) an intermolecular single-quantum coherent signal selection module, an indirect dimension evolution period t1 module, an indirect dimension evolution period t2 module and a signal sampling period t3 module of the intermolecular single-quantum coherent two-dimensional J-resolved spectroscopy pulse sequence are opened, and experiment parameters of the modules of the intermolecular single-quantum coherent two-dimensional J-resolved spectroscopy pulse sequence are set; (4) the intermolecular single-quantum coherent two-dimensional J-resolved spectroscopy pulse sequence with the experiment parameters set in the step (3) is executed, and data sampling is carried out; (5) after data sampling is accomplished, related data post-processing is carried out to obtain the high-resolution two-dimensional J-resolved spectroscopy free from influence of the non-uniform magnetic field.

A Toroid Cavity Detector (TCD) is provided for implementing nuclear magnetic resonance (NMR) studies of chemical reactions under conditions of high pressures and temperatures. A toroid cavity contains an elongated central conductor extending within the toroid cavity. The toroid cavity and central conductor generate an RF magnetic field for NMR analysis. A flow-through capillary sample container is located within the toroid cavity adjacent to the central conductor to subject a sample material flowing through the capillary to a static magnetic field and to enable NMR spectra to be recorded of the material in the capillary under a temperature and high pressure environment.

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 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 nuclear magnetic resonance (NMR) device based on a laser atomic magnetometer, and the NMR device comprises a cesium atom vapor bubble, a magnetic shielding bushing which is sleeved on the cesium atom vapor bubble, three groups of Helmholtz coils which are arranged inside the magnetic shielding bushing, a polarization device which is used for polarizing cesium atoms inside the cesium atom vapor bubble, a laser transmitting device which is used for transmitting detection laser to the cesium atom vapor bubble, a detection device which is used for detecting an NMR signal of the detection laser penetrating the cesium atom vapor bubble and a pneumatic sample feeding device which is used for pre-polarizing a sample to be detected and can place the pre-polarized sample on the cesium atom vapor bubble. The invention also discloses a measurement method of an NMR based on the laser atomic magnetometer. The device and the method are high in detection sensitivity, free from needing low-temperature refrigeration, low in running cost and lower in working temperature.

A method for obtaining a nuclear magnetic resonance two-dimension spin echo related spectrum under an uneven magnetic field relates to a nuclear magnetic resonance wave spectrum detection method and comprises the steps of using a normal one-dimension pulse sequence to sample a one-dimension spectrum, obtaining the line width of spectral lines, and providing a basis for spectrum width parameter setting, wherein the line width value also reflects the uniformity condition of a magnetic field; introducing well precompiled two-dimension spin echo related spectrum pulse sequences onto a nuclear magnetic resonance spectrometer; opening a multi-quantum coherent signal selection module, a three-dimension sampled indirect dimension evolution period t1 combination and indirect dimension evolution period t2 combination and an echo delay module among the two-dimension spin echo related spectrum pulse sequences; setting each experiment parameter of the two-dimension spin echo related spectrum pulse sequences; executing the two-dimension spin echo related spectrum pulse sequences, of which the experiment parameters are set, for data sampling; after the data sampling is finished, performing related data postprocessing to obtain the two-dimension spin echo related spectrum uninfluenced by the uneven magnetic field. The method has no need of shimming operation and is simple, convenient and effective.

The invention provides a shale pore structure detection method based on nuclear magnetic resonance. The method comprises the steps that a sample is processed into a cylinder; the sample is saturated with water at normal pressure for 12h, and then is taken out; CPMG pulse sequence test is carried out on the sample to acquire a spin-echo-series attenuation signal; the spin-echo-series signal is inversed to acquire a T2 spectrum distribution diagram and the details of each peak; and the T2 spectrum of acquired same sample under water saturation and centrifugation is analyzed in a coordinate system to acquire the change of the volume and quantity of pores of the sample. The shale pore structure is mainly studied in a saturated water state in the prior art of nuclear magnetic resonance, and the problems that the study angle is single and limited; only pore distribution can be studied; and fracture prediction cannot be carried out are solved. The method provided by the invention belongs to the technical field of petroleum exploration and development.