Understanding the effect of elliptical polarization in surface nuclear magnetic resonance method
Liu Dao-Han1, Hu Xiang-Yun1, and Li Yaoguo1,2
1. Institute of Geophysics & Geomatics, China University of Geosciences, Wuhan, Hubei 430074, China.
2. Department of Geophysics, Colorado School of Mines, Golden, Colorado 80401, USA.
Abstract：
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 signifi cantly affect SNMR response and it is essential to include elliptical polarization in SNMR modeling and data interpretation.
LIU Dao-Han,HU Xiang-Yun,LI Yao-Guo. Understanding the effect of elliptical polarization in surface nuclear magnetic resonance method[J]. APPLIED GEOPHYSICS, 2012, 9(4): 365-377.
[1]
Boucher, M., Favreau, G., Vouillamoz, J. M., Nazoumou, Y., and Legchenko, A., 2009, Estimating specific yield and transmissivity with magnetic resonance sounding in an unconfined sandstone aquifer (Niger): Hydrogeology Journal, 17(7), 1805 - 1815.
[2]
Chalikakis, K., Nielsen, M. R., and Legchenko, A., 2008, MRS applicability for a study of glacial sedimentary aquifers in Central Jutland, Denmark: Journal of Applied Geophysics, 66(3 - 4), 176 - 187.
[3]
Chalikakis, K., Nielsen, M. R., Legchenko, A. and Hagensen, T. F., 2009, Investigation of sedimentary aquifers in Denmark using the magnetic resonance sounding method (MRS): Comptes Rendus Geoscience, 341 (10 - 11), 918 - 927.
[4]
Chave, A. D., 1983, Numerical integration of related Hankel transforms by quadrature and continued fraction expansion: Geophysics, 12(48), 1671 - 1685.
[5]
Dai, M., Hu, X. Y., and Wu, H. B., 2007, Surface nuclear magnetic resonance inversion: Chinese J. Geophys. (in Chinese), (10), 2676 - 2682.
[6]
Dai, M., 2008, Surface nuclear magnetic resonance forward and inversion research: Master’s thesis, China University of Geosciences (Wuhan), Wuhan.
[7]
Dai, M., Hu, X. Y., and Cheng, Y. P., 2009, High precision numerical simulation for large loop source vertical excited field: Geological Science and Technology Information, 28(2), 122 - 126.
[8]
Hertrich, M., 2005, Magnetic Resonance Sounding with separated transmitter and receiver loops for the investigation of 2D water content distributions: PhD Thesis, Technical University of Berlin.
[9]
Hu, X. L., Tang, H. M., Ma, S. Z., and Zhang, G. C., 2006, Numerical simulation of the 3D landslide stability in Three Gorges Area Based on NMR: Earth Science -Journal of China University of Geosciences, 31(2), 279 - 284.
[10]
Hertrich, M., Braun, M., Gunther, T., Green, A. G., and Yaramanci, U., 2007, Surface nuclear magnetic resonance tomography: Ieee Transactions on Geoscience and Remote Sensing, 45(11), 3752 - 3759.
[11]
Hertrich, M., Green, A. G., Braun, M., and Yaramanci, U., 2009, High-resolution surface NMR tomography of shallow aquifers based on multi-offset measurements: Geophysics, 74(6), 47 - 59.
[12]
Legchenko, A., Ezersky, M., Camerlynck, C., Al-Zoubi, A., and Chalikakis, K., 2009, Joint use of TEM and MRS methods in a complex geological setting: Comptes Rendus Geoscience, 341(10-11), 908 - 917.
[13]
Legchenko, A., and Valla, P., 2002, A review of the basic principles for proton magnetic resonance sounding measurements: Journal of Applied Geophysics, 50(1 - 2), 3 - 19.
[14]
Li, Z. Y., Pan, Y. L., Tang, H. M., Zhang, B., Gu, T., and Wang, P., 2004, A new achievement in using the magnetic resonance sounding method—MRS applied in detecting landslip in the three gorges and archaeology in mausoleum of the first qin emperor: Proceeding of CT and 3D Imaging Conference, 104.
[15]
Lin, J. Y., 2010, Research on forward and inversion of nuclear magnetic resonance for water exploration: Master’s thesis, China University of Geosciences (Beijing), Beijing.
[16]
Pan, Y. L., and Zhang, C. D., 2000, Theory and method of surface nuclear magnetic resonance: China University of Geosciences Press, .
[17]
Pan, Y. L.,Wan L., and Yuan, Z., L., 2000, Current status and development trend of detecting underground water with magnetic resonance: Geological Science and Technology Information, 19(1), 105 - 108.
[18]
Petke, M. M., and Yaramanci, U., 2010, QT inversion - Comprehensive use of the complete surface NMR data set: Geophysics, 75(4), 199 - 209.
[19]
Trushkin, D. V., Shushakov, O. A., and Legchenko, A. V., 1995, Surface NMR applied to an electroconductive medium: Geophysical Prospecting, 43(5), 623 - 633.
[20]
Wang, P., 2007, Three dimensional forward of surface nuclear magnetic resonance in uniformity medium: Master’s thesis, China University of Geosciences (Wuhan), Wuhan.
[21]
Weichman, P. B., Lavely, E. M., and Ritzwoller, M. H., 2000, Theory of surface nuclear magnetic resonance with applications to geophysical imaging problems: Physical Review E, 62(1), 1290 - 1312.
[22]
Weng, A. H., and Wang, X. Q., 2007, Forward simulation with high accuracy of ground nuclear magnetic resonance: Journal of Jilin University( Earth Science Edition), 37(3), 620 - 623.
[23]
Weng, A. H., Wang, X. Q., and Liu,G. X., 2007, Nonlinear inversion of surface nuclear magnetic resonance over electrically conductive medium: Chinese J. Geophys. (in Chinese), 50(3), 890 - 896.
[24]
Yaramanci, U., Legchenko, A., and Roy, J., 2008, Magnetic Resonance Sounding Special Issue of Journal of Applied Geophysics: Journal of Applied Geophysics, 66 (3-4), 71-72.
[25]
Yuan, Z. L., Wan, L., and Li, Z. Y., 2001, Under-ground water detecting effect of the nuclear magnetic resonance method in the water-poor area: Journal of Applied Sciences, 19(3), 265 - 267.
[26]
Zhang, R., Hu, X. Y., Yang, D. K., Hao, X. Z., and Dai, M., 2006, Review of development of surface nuclear magnetic resonance: Progress in Geophysics, 21(1), 284 - 289.
2012, Vol. 9 
|
