Detecting induced polarisation effects in time-domain data: a modelling study using stretched exponentials

摘要

The potential for extracting and interpreting induced polarisation (IP) data from airborne surveysis now broadly recognised. There is, however, still considerable discussion about the conditionsunder which the technique can provide knowledge about the subsurface and thus, its practicalapplications. Foremost among these is whether, or under what conditions, airborne IP can detectchargeable bodies at depth. To investigate, we focus on data obtained from a coincident-looptime-domain system. Our analysis is expedited by using a stretched exponential rather than aCole-Cole model to represent the IP phenomenon. Our paper begins with an example that illuminatesthe physical understanding about how negative transients (the typical signature of an IPsignal in airborne data) can be generated. The effects of the background conductivity are investigated;this study shows that a moderately conductive and chargeable target in a resistive hostis an ideal scenario for generating strong IP signals. We then examine the important topic ofestimating the maximum depth of the chargeable target that can generate negative transients.Lastly, some common chargeable earth-materials are discussed and their typical IP time-domainfeatures are analysed. The results presented in this paper can be reproduced and further exploredby accessing the provided Jupyter notebooks.