1-D SNMR FORWARD MODELLING IN HYDROLOGICAL INVESTIGATIONS

Abstract

The Surface NMR technique is based on the basic principle of nuclear magnetic resonance (NMR) technique. It was in the early 1980s that SNMR technique was employed for groundwater and hydrocarbon exploration Recognized as a non- intrusive geophysical method, it - had many advantages over the other known geophysical methods used for the same purpose. The main advantage is that the NMR signal can be directly measured from the water molecules. We - are confronted with various obstacles when dealing with other geophysical methods for direct detection of groundwater which is easily overcome using this technique. SNMR measurements provide bulk information about the subsurface from which various hydro-gco logical parameters can be evaluated and studied. In the present effort, the individual contributions of different regions of the subsurface to total NMR signal measured on the surface have been computed. One-dimensional SNMR modeling has been done to calculate NMR signal amplitude for assumed depth-wise water saturation for different current values. Developed scheme has been tested over several synthetic multi-layered earth models and also verified with the help of a case study.