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f INCORPORATING DEPHASING DYNAMICS INTO SNMR FID INVERSIONS IN THE HIGH PLAINS AQUIFER
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 25th Symposium on the Application of Geophpysics to Engineering & Environmental Problems, Mar 2012, cp-329-00150
Abstract
While it is accepted that T2 and T2 * diverge under most surface NMR (SNMR) conditions, the mechanism for this difference is usually not accounted for in the forward modeling kernels. In SNMR T2 * is often used as a proxy for T2 in the equations used to map NMR to aquifer characteristics. The reason that T2 and T2 * are not equivalent is due to inhomogeneities in the static magnetic field. As the Larmor frequency is a function of the static field, any inhomogeneity causes the spins to dephase and lose coherence. This dephasing causes non-exponential decay in the recorded FID time series.