High-resolution ground nuclear magnetic resonance imaging method

Abstract

The invention provides a high-resolution ground nuclear magnetic resonance imaging method, solving the problem that the traditional ground nuclear magnetic resonance imaging method meets the bottleneck in the aspect of further improving the interpretation precision of underground water. A damping method least square method is applied, a nuclear magnetic resonance electromagnetic field and a seismic wave field equation are solved, and wave field conversion is achieved, and the seismic wave field discrete data of each receiving coil on the measuring line can be obtained; the deconvolution is obtained by fitting seismic wave field discrete data to each receiving coil on the measuring line, the waveform broadening effect of the wave field conversion is eliminated; the mutual relation of all points in the synthetic aperture range is obtained on the basis of the related superposition principle, so that correlation point superposition is realized, the detection signal-to-noise ratio is improved, and the synthetic aperture virtual seismic wave field composite value on the measuring line is obtained; by means of the Kirchhoff's migration imaging theory, the seismic wave fluctuation equationis solved to realize the underground water-containing structure migration imaging. The high-precision imaging of the water-containing layer is achieved based on mathematical integration transformation between the nuclear magnetic resonance response diffusion field and the pseudo-seismic fluctuation field, and the defects that a traditional nuclear magnetic resonance data interpretation method ispoor in water-containing layer edge resolution are avoided, and the method has certain significance for further application and popularization of the ground nuclear magnetic resonance technology.

Description

technical field [0001] The invention relates to a high-resolution ground nuclear magnetic resonance imaging method, which belongs to the technical field of ground nuclear magnetic resonance geophysical exploration methods. Background technique [0002] Surface Nuclear Magnetic Resonance (SNMR) is an emerging geophysical method in recent years, mainly used in shallow groundwater exploration and prediction of water-sourced geological hazards. During detection, coils are laid on the ground to emit an AC field of hydrogen proton spin frequency underground, which excites groundwater to generate nuclear magnetic resonance signals, and determines the water content and porosity of the aquifer through inversion, imaging and other processes, with direct non-invasive detection , quantitative and qualitative, and rich in information. [0003] However, the existing SNMR technology signals are very weak, only at the nanovolt level. Although the location and content information of water c...

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Problems solved by technology

[0003] However, the existing SNMR technology signal is very weak, only nanovolt level, although it can realize the acquisition of water content position and content information, but the detection signal-to-noise ratio and the resolution of the edge of the aquifer are low, and it is difficult to achieve accurate delineation of the water content range

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