A Novel Use of NMR Measurements for In-Situ Monitoring of Geochemical Reactions
Many natural and controlled processes in the near-surface region of Earth, involve geochemical reactions that lead to changes in the mineralogic form of iron. Measurements made to study, and/or monitor such reactions typically require methods of direct sampling that can perturb or disrupt the region of interest.
NMR measurements can be made remotely using a surface-based NMR system, or in a borehole using NMR logging. It is well known that the presence of iron affects NMR relaxation times. We are exploring the use of NMR measurements as a way to determine the mineralogic form of the iron, and thus monitor geochemical reactions that result in changes in iron mineralogy.
Sands coated with different Fe(II) and Fe(III) minerals display significant differences in the NMR response. (Keating and Knight, 2007, 2008).
Scott Fendorf, Stanford University
Project Publications and Presentations
- Keating, K. and Knight, R. (2010), A laboratory study of the effect of Fe(II)-bearing minerals on NMR relaxation measurements, Geophysics, v. 75; no. 3; p. F71-F82; DOI: 10.1190/1.3386573
- Keating, K., Knight, R., and Tufano, K., Nuclear magnetic resonance relaxation measurements as a means of monitoring iron mineralization processes, Geophysical Research Letters, 35, L19405, doi:10.1029/2008GL035225, 2008.