Understanding the effect of elliptical polarization in surface nuclear magnetic resonance method

作者：Liu Dao-Han; Hu Xiang-Yun^*; Li Yaoguo

来源：Applied Geophysics, 2012, 9(4): 365-377.

DOI：10.1007/s11770-012-0348-y

• SNMR
• Chave algorithm
• elliptical polarization
• phase lag

Currently, surface nuclear magnetic resonance (SNMR) method is the only geophysical method that detects groundwater directly. In this paper, we investigate the effect of elliptical polarization in the perpendicular excitation magnetic field. The effect of elliptical polarization is clearly visible in our ellipticity calculation and it can cause strong distortion to the excitation field in the presence of high subsurface conductivities. By examining the co-rotating and counter-rotating components of the field, we show that elliptical polarization affects transmitting and receiving processes differently and that a clear phase lag exists between transmitter loop and receiver loop. Finally, we derive the response function of coincident loops and calculate proton tip angles, the kernel function and SNMR response curves of a 1D aquifer model. Based on the simulations, we conclude that the elliptical polarization and phase lag can significantly affect SNMR response and it is essential to include elliptical polarization in SNMR modeling and data interpretation.

• 出版日期2012-12
• 单位中国地质大学（北京）