Correlation analysis and imaging technique of TEM data

Abstract

Although the transient electromagnetic method (TEM) has been used in geo-exploration for many years, the inversion precision of TEM data is still very limited and new techniques are needed to improve TEM data interpretation. Mathematically, TEM data can be converted into a series of virtual waves. Multi-aperture electromagnetic modelling shows that the coherence of multi-aperture TEM and echo waves measured at adjacent positions from the same geological body is high. Therefore, it is feasible to apply multi-aperture synthesis to TEM data. Based on the idea of synthetic aperture radar, a new data-processing method has been developed that uses superposition to realise multi-aperture data integration as well as Kirchhoff migration and imaging. After the pseudo-wavelet extraction from TEM data, the traditional approach of profile-based multi-aperture synthesis has been developed for each survey station. Furthermore, the traditional single point approach was applied for multiple point coverage. The technology of synthetic aperture improves TEM resolution, rendering it possible to extract information from TEM data that cannot be obtained by conventional methods. Experiments with both synthetic and survey data show that synthetic aperture imaging is effective, paving the way for developing a new TEM imaging technology.