Analysis and Inhibition Method of Array-Type SNMR Receiving Coil Coupling

Abstract

Surface nuclear magnetic resonance (SNMR) is currently the only geophysical method for directly finding groundwater. The array-type SNMR detection method can effectively obtain the 2-D or 3-D images of groundwater. However, the mutual inductance between multiple receiver coils affects the signal acquisition and data interpretation. In this article, we propose a decoupling circuit to inhibit the effect of this coupling phenomenon. We analyze the influence of the coupling phenomenon on the received signal and inversion through theoretical derivation and simulation. Then, we solve the electrical parameter equations for the decoupling circuit by modeling the coil and the decoupling circuit. Experiments conducted in an electromagnetic shielded room preliminarily prove that the decoupling circuit we designed can effectively suppress the change in the signal amplitude caused by the coupling phenomenon. In order to verify the effect of this method in a field experiment, we tested it in Yuhua Park, Changchun City, and used the decoupled data to invert the 2-D groundwater distribution. The results match the known hydrogeological information.