Research on response signal characteristics of SNMR transverse gradient coil devices for different aquifers

Abstract

[Objective] The surface nuclear magnetic resonance(SNMR) method for groundwater exploration is a highly promising technique with exceptional detection performance. Traditionally, SNMR operates using a co-located transmitter-receiver coil to excite and receive signals for groundwater detection. The objective is to diversify SNMR operational modes and enhance the accuracy of groundwater detection using SNMR method. [Methods] A simulation analysis was conducted on the signal characteristics of the SNMR transverse gradient coil device in groundwater detection, followed by field experiments in the river beach area along the Han River in Tianmen to validate the result. [Results] The response signal of the transverse gradient coil device showed an approximate positive correlation with water content and aquifer thickness, and a negative correlation with aquifer depth. The difference analysis of the transverse gradient coil signals revealed that the occurrence of zero values in the signal difference, as well as the pulse moment magnitude corresponding to the signal peak, can qualitatively indicate the aquifer depth. Additionally, combining the gradient signal difference with the original coil signal for joint inversion can significantly improve the inversion accuracy of the SNMR method. [Conclusion] The findings demonstrate that utilizing the SNMR transverse gradient coil device is an effective approach to improving the accuracy of groundwater detection.

Keywords

surface nuclear magnetic resonance / gradient coil / groundwater / signal difference / signal characteristics / influencing factors