A Forward and Inversion Method of Prepolarization Field Magnetic Resonance Based on the Broadening Exponent c
A magnetic resonance and forward and inversion technology, which is applied in electron magnetic resonance/nuclear magnetic resonance detection, electric/magnetic exploration, acoustic re-radiation, etc., can solve problems such as increased difficulty of calculation, slow calculation speed, and large amount of data , to achieve the effect of improving inversion accuracy, maintaining calculation speed, and fast calculation
Active Publication Date: 2021-08-27
JILIN UNIV
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[0004] The QT inversion-Comprehensive use of the complete surface NMR data set in the above paper QT (GEOPHYSICS volume: 75: 4 pages WA199-WA209) inversion solves the problem of one-dimensional ground NMR inversion, and is currently the most stable 3D NMR inversion method, but it is a full-wave inversion, and the amount of data is large in single-exponential inversion. If multi-exponential inversion is used, the calculation difficulty will be greatly increased, which is difficult to achieve in 3D and 2D inversion.
The above paper Pore size distributions and hydraulic conductivities of rocks derived from Magnetic Resonance Sounding relaxation data using multi-exponential decay time inversion (JOURNAL OF APPLIED GEOPHYSICS volume: 66 issues: 3-4 pages: 73-81 special issue: SI) adopts multi-exponential fitting method, the amount of inversion data is too large, the calculation speed is slow, and it is not practical in practical applications
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[0078] Below in conjunction with accompanying drawing and embodiment the present invention is described in further detail;
[0079] The one-dimensional surface nuclear magnetic resonance forward and inversion method based on the broadening index C of the present invention is suitable for high-efficiency and high-resolution detection of layered water bodies, and can reliably obtain high-precision and smooth inversion results while maintaining calculation time Inversion method, this method transmits an alternating current whose frequency is the local Larmor frequency to the ground through a transmitting coil to generate an induced magnetic field. Under the action of the induced magnetic field, the hydrogen protons in the groundwater produce energy level transitions, and a large number of hydrogen protons transition to high energy levels. When the supply current is removed, these high-energy hydrogen protons will gradually return to the low-energy state, releasing a large number ...
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The invention relates to a geophysical detection method and its data inversion interpretation, which can improve the accuracy of single-exponential fitting of free decay signals, and avoid the problem of excessive data volume of multi-exponential fitting, by making the direction of the geomagnetic field as The x-axis, the y-axis perpendicular to the direction of the geomagnetic field on the horizontal plane, and the z-axis vertically downward to the ground, calculate the sensitivity kernel function K of the underground space position from the initial amplitude data, use the nuclear magnetic resonance full-wave signal to carry out forward and inversion, and pass Jihong The Knopf method searches for regularization parameters, and the Gauss-Newton iterative method is used to solve the objective function. The conjugate gradient method is used to obtain the model increment of each iteration, and the linear search is used to obtain the optimal search step size.
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Technical field: [0001] The invention relates to a geophysical detection method and its data inversion interpretation, which can improve the accuracy of single-exponential fitting of free-attenuation signals, and avoid the problem of excessive data volume of multi-exponential fitting. Resonance Sounding (MRS) can efficiently and accurately detect layered groundwater structures. Background technique: [0002] Surface Nuclear Magnetic Resonance (SNMR for short) is a new geophysical method for directly detecting groundwater developed internationally. The exploration and evaluation of groundwater resources in water-scarce areas can also play a unique role in the detection and early warning of water sources for geological disasters such as dam leakage, mine water inrush, tunnel water gushing, and landslides caused by groundwater. [0003] Mike Mueller-Petke and Ugur Yaramanci proposed a new inversion method, namely QT inversion, in the paper QT inversion-Comprehensive use of the...
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IPC IPC(8): G01V3/38G01V3/14
CPCG01V3/14G01V3/38
Inventor 林婷婷叶瑞杨玉晶赵汗青周坤
Owner JILIN UNIV