A Comparative Study of Subsurface Earth Classification Between Two Dimensional and Three Dimensional Geoelectrical Imaging in University of Benin Teaching Hospital, Benin City, Nigeria

Authors: Avenbuan N, Alile OM, Iduseri OM

DOI Info: N/A

ABSTRACT

The two-dimensional (2D) and three-dimensional (3D) geoelectrical methods of exploration are mostly used in complex and inhomogeneous subsurface media. In a 2D inversion program, the earth is assumed to have a 2D resistivity distribution. However, the resistivity distribution of the earth is inherently 3D. To establish the similarities and dissimilarities between these two survey methods, data were obtained along parallel and orthogonal lines using the Wenner-Schlumberger Array configuration technique at the University of Benin Teaching Hospital Field, Benin City, Nigeria. A 3D data was obtained by combining series of 2D parallel and orthogonal data set using a batch file. The 2D orthogonal and parallel data set were processed using RES2DINV, while the resulting 3D data set was processed using RES3DINV software to obtain the 2D and 3D inversion results. The 3D inversion results were exported to a Voxler software where the volume image of the subsurface was obtained. The 2D and 3D inversion results gave same depths for each layer and exact positions of the anomalies along the imaging planes (survey lines). However, the 2D inversions gave lower resistivity values of the observed anomalies when compared with the resistivity values reported by the 3D inversions. These anomalies were folded onto the imaging planes and presented as anomalies along the planes. A comparison of the acquired field data set, the 2D and 3D inversion results showed that the 3D inversions gave better representations of each resistivity zones and clearly showed the resistivity variations of the various anomalies along and off the imaging planes with depths.

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