Ground magnetic resonance detection device and method for shallow groundwater and hydrocarbon substances

Abstract

The invention discloses a ground magnetic resonance detection device and method for shallow groundwater and hydrocarbon substances, and belongs to the field of geophysical exploration. The device is composed of an upper computer, a main control module, a DC-DC converter, an H-bridge transmitting module, a switch driving module, an acquisition card, a storage battery, a transmitting coil Tx, a receiving coil Rx1, a receiving coil Rx2, a switch group, a pre-amplification module, a band-pass filtering module, a sliding rail driver and a supporting rod sliding rail. The two receiving coils are distributed on the two sides of the transmitting coil at equal intervals to form a symmetrical structure, the influence of the transmitting coil on the receiving coils is counteracted in an ultra-shallowlayer or short relaxation fine detection mode, dead time generated by coupling can be completely eliminated, and complete magnetic resonance signals are obtained. In an ultra-shallow layer or short relaxation fine detection mode, the difference between induction signals of the two receiving coils is obtained, effective magnetic resonance signals are reserved, meanwhile, far-end environment noiseis suppressed from the source, and the signal-to-noise ratio is effectively increased.

Description

technical field [0001] The invention belongs to the field of geophysical exploration, and in particular relates to a ground magnetic resonance detection device and method for shallow groundwater and hydrocarbon substances. Background technique [0002] Ground magnetic resonance technology (Magnetic Resonance Sounding, MRS) is a geophysical method that uses the relaxation phenomenon of hydrogen protons after being excited. It is mainly used for non-destructive inspection of groundwater and hydrocarbon organic pollutants. It has qualitative and quantitative characteristics. . [0003] In the traditional detection method, a transmitting coil and a receiving coil of the same size are overlapped on the ground. The transmitting system transmits an excitation pulse to the ground through the transmitting coil to excite the hydrogen protons in groundwater or hydrocarbon substances. After removing the pulse, the closed The switch connects the receiving coil to the post-stage circuit ...

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Problems solved by technology

However, this method still has a dead time during detection, which cannot solve the problem of early high-amplitude effective MRI signal loss, and cannot effectively measure the target to be measured with a short relaxation time

[0005] Li Tong. Research on ground magnetic resonance early signal detection and frequency domain segmental noise reduction method [D]. Jilin University, 2015 proposed Q-switch technology to reduce the energy release time of the receiving coil to shorten the dead time, but it still cannot fundamentally Firstly, the dead time is eliminated; secondly, the influence of environmental noise is reduced by using the method of reference noise reduction. This method can suppress the noise to a certain extent, but in the environment with strong noise, the signal-to-noise ratio is low. Traditional ground magnetic resonance Technology still doesn't work effectively

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