2017_EJRNL_PP_OLALEKAN_FAYEMI_1.pdf
Terbatas  
» Gedung UPT Perpustakaan
Terbatas  
» Gedung UPT Perpustakaan
This paper introduces new technique for qualitative analysis of multi-transient electromagnetic (MTEM) earth
impulse response over complex geological structures. Instantaneous phase and frequency attributes were used
in place of the conventional common offset section for improved qualitative interpretation of MTEM data by
obtaining more detailed information from the earth impulse response. The instantaneous attributes were used
to describe the lateral variation in subsurface resistivity and the visible geological structure with respect to
given offsets. Instantaneous phase attribute was obtained by converting the impulse response into a complex
form using the Hilbert transform. Conversely, the polynomial phase difference (PPD) estimator was favored
over the center finite difference (CFD) approximation method in calculating the instantaneous frequency attribute
because it is computationally efficient and has the ability to give a smooth variation of the instantaneous frequency
over a common offset section. The observed results from the instantaneous attributes were in good
agreement with both the subsurface model used and the apparent resistivity section obtained from the MTEM
earth impulse response. Hence, this study confirms the capability of both instantaneous phase and frequency attributes
as highly effective tools for MTEM qualitative analysis.