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

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 priorimodel for subsequent regularized inversion.Theadvantageofmigration is that it doesnot require anyapriori informationabout the typeof the sources present, nordoes it relyon regularization as per inversion.Migration is very stablewith 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.The3DmigrationofTMIdata acquiredover the Reid-Mahaffy test site in Ontario, Canada is used as a test study.Our results are shown to be consistentwith 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.