3D migration for rapid imaging of total-magnetic-intensity data

Abstract

ABSTRACT Three-dimensional potential field migration for rapid imaging of entire total-magnetic-intensity (TMI) surveys is introduced, and real time applications are discussed. Potential field migration is based on a direct integral transformation of the measured TMI data into a 3D susceptibility model, which could be directly used for interpretation or as an a priori model for subsequent regularized inversion. The advantage of migration is that it does not require any a priori information about the type of the sources present, nor does it rely on regularization as per inversion. Migration is very stable with respect to noise in measured data because the transform is reduced to the downward continuation of a function that is analytical everywhere in the subsurface. The 3D migration of TMI data acquired over the Reid-Mahaffy test site in Ontario, Canada is used as a test study. Our results are shown to be consistent with those results obtained from 3D regularized inversion as well as the known geology of the area. Interestingly, the migration of raw TMI data produces results very similar to the inversion of diurnally corrected and microleveled TMI data, suggesting that migration could be applied directly to real-time imaging during the acquisition.