Numerical Evaluation of 3D Geoelectrical Resistivity Imaging for Environmental and Engineering Investigations Using Orthogonal 2D Profiles
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Abstract
Description
Field design for 3D data acquisition in geoelectrical
resistivity imaging using a net of orthogonal sets of 2D
profiles was numerically investigated. A series of 2D
apparent resistivity pseudosections were generated over a
synthetic horst structure representing the geological
environment of a crystalline basement in low latitude
areas using RES2DMOD code. Different minimum
electrode separations and inter-line spacing were used
with a view of determining the optimum inter-line
spacing relative to the minimum electrode separation.
The 2D apparent resistivity data were collated to 3D data
set and then inverted using RES3DINV, a full 3D
inversion code. The relative effectiveness and imaging
capabilities of Wenner-alpha (WA), Wenner-beta (WB),
Wenner-Schlumberger (WSC), dipole-dipole (DDP),
pole-dipole (PDP), and pole-pole (PP) arrays to image
the structure using a net of orthogonal set of 2D profiles
are presented. The normalized average sensitivity of the
inversion results show that WSC, DDP, and PDP arrays
are more sensitive to the 3D structure investigated. Interline
spacing of not greater than four times the minimum
electrode separation gives reasonable resolution.
Keywords
QC Physics, QE Geology