EMinar 3.13: Bryan James - Interferographic TEM Method: Array Beamforming for Resolution Improvement

Описание: In this webinar, a new method of array processing of semi-airborne multi-source, multi-receiver TEM data is introduced using beamforming techniques, inspired by their use in other technical fields, to synthetically form impulsive distributions of TEM fields that improve resolution of subsurface geoelectric structure. This form of array processing, currently formulated for 2D problems, is discussed to highlight the fundamental relationship to field interference beamforming methods. The degree of subsurface electric field compaction and magnetic field profile compaction into impulsive distributions is shown to be substantial and depends on depth. The interferographic processing results are then used in a straightforward subsurface imaging procedure for which results are presented for two modeled structural cases: a buried basin and a buried horst. Results are dependent on a reference model and is addressed in detail for the modeled data. Robustness of the interferographic processing is shown with the addition of random noise to the data. Interferographic results for the structural models are also compared with inversion results. Lastly, a brief resolution exercise shows that interferographic processing is an improvement over regular data forms for defining the minimum horizontal separation visibility for two small targets, a direct resolution estimation analogous to that used in signal processing to determine minimum frequency separation of two signals. The future economic commercialization of the ITEM survey design is viable with a set of sparse ground-based sources and high density acquisition for each source position with drone-based receivers.