Author(s)

M. EZEOKE, K. TONG & S. SHI

Abstract

A practical approach is proposed and used to investigate the electromagnetic (EM) signature of bare- faced terrain using 3D computer electromagnetic models (CEM). Six barefaced terrain types with different electrical, physical and chemical properties were investigated. They comprise homogeneous and heterogeneous terrain. The approach developed CEMs in software using reflectance spectroscopy and dielectric permittivity data. EM signature models of the barefaced terrain are based on finite inte- gration technique (FIT) solvers. The developed technique and models are valid for diverse materials under test including unconventional petroleum resources like shale rock and oil sands. The remote sensing of terrain from airborne or satellite synthetic aperture radar requires a prior determination of the EM signature for accurate classification. The implementation of our new method combined empirical measurements and FIT in three steps. Geochemical properties determined using reflectance spectros- copy in the mid-infrared region (2.5–25 µm) identified the presence of bitumen, clay and moisture in Nigerian oil sands while reststrahlen effects were observed in beach sand compared with gravel and pebble. Also new information on both real, e′r and imaginary, e′r permittivity of terrain was experimentally obtained for frequency varying from 1 to 11 GHz. After post-processing, the results differed from expectation of complex refractive index method for petrophysics although adequate Kramers–Krönig correlation between measured real, e′r and imaginary, e′r permittivity data was exhibited. Our approach uses the results to improve the CEMs for superior EM signature determination. An application of our new technique to land degradation monitoring using radar is also presented.

Keywords

Barefaced terrain, complex refractive index method, computer electromagnetic model, dielectric permittivity, finite integration technique, oil sand, radar, radar signature, remote sensing, synthetic aperture radar, unconventional petroleum exploration.