Inductive Coupling and Spectral IP Parameter Resolution with Modern Survey Designs
L. Cox and M. Zhdanov
Event name: 81st EAGE Conference and Exhibition 2019
Session: Poster: Near Surface - Mining and Technologies
Publication date: 03 June 2019
Info: Extended abstract, PDF ( 980.22Kb )
Price: € 20
Spectral IP methods can be used not only for mineral detection, but for mineral discrimination. To do this, broadband complex resistivity information about the earth’s response must be collected and analysed. As surveys become more complex and truly 3D, it is more difficult to eliminate inductive coupling (IC). In this paper, we look at the effects of inductive coupling and advanced survey designs in the context of extracting spectral IP information. We examine the effects of resolving both the chargeability and time constant of a domain in the presence of IC with modern 3D survey geometries. What we find is that IC effects cannot be avoided with large bandwidth spectral IP data and complex survey designs. Frequency domain data are much more affected by the IC effects than the time domain data. Most of the IC effect is due to wire to wire coupling, not the EM induction effects in the earth. This means that simply using the full sets of Maxwell’s equations, but not including the true wire path is not sufficient for accurate modeling. The time constants can likely be determined even in the presence of IC if the full EM solution is used for modeling and inversion.