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| A study of the influence of paramagnetic material on the signal of NMR |
| TANG Ke-Xuan1, 2, LI Jun-Li3, LI Zhen-Yu2, ZHU Yuan-Ting2, ZHANG Wen-Bo2 |
1.China Water Resources Beifang Investigation,Design and Research Co. Ltd.,Tianjin 300222, China;
2.Institute of Geophysics and Geomatics,China University of Geosciences(Wuhan),Wuhan 430074, China;
3.Affiliated Hospital,China University of Geosciences(Wuhan),Wuhan 430074, China |
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Abstract Susceptibility of paramagnetic material changes when the temperature changes, and non-uniform magnetic field will have a certain influence on nuclear magnetic resonance (NMR) signal. In the study of physical properties of frozen soil with NMR, the effects caused by paramagnetic material in frozen soil cannot be ignored. In combination with the studies of physical properties test of frozen soil conducted both in China and abroad, the authors mixed Fe2O3 with Malan loess and water to make samples in which Fe2O3 values were different and initial water values were the same. Then the authors analyzed the relaxation characteristics of the samples. Through the analysis of the NMR signal amplitude and transverse relaxation time of the samples with the change of temperature, the influence of different paramagnetic values on NMR signal of frozen soil was summarized. The results show that the paramagnetic material can reduce NMR signal amplitude and transverse relaxation time of fluid in porous media significantly. The NMR signal and paramagnetic content meets some empirical formula below 0℃, and the paramagnetic material will cause some errors in the unfrozen water content calculation of the samples.
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Received: 08 September 2017
Published: 20 December 2017
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