Computation of Optimized Arrays for 3-D Electrical Imaging Surveys

Abstract

S U M M A R Y3-D electrical resistivity surveys and inversion models are required to accurately resolve structures in areas with very complex geology where 2-D models might suffer from artefacts. Many 3-D surveys use a grid where the number of electrodes along one direction (x) is much greater than in the perpendicular direction (y). Frequently, due to limitations in the number of independent electrodes in the multi-electrode system, the surveys use a roll-along system with a small number of parallel survey lines aligned along the x-direction. The 'Compare R' array optimization method previously used for 2-D surveys is adapted for such 3-D surveys. Offset versions of the inline arrays used in 2-D surveys are included in the number of possible arrays (the comprehensive data set) to improve the sensitivity to structures in between the lines. The array geometric factor and its relative error are used to filter out potentially unstable arrays in the construction of the comprehensive data set. Comparisons of the conventional (consisting of dipole-dipole and Wenner-Schlumberger arrays) and optimized arrays are made using a synthetic model and experimental measurements in a tank. The tests show that structures located between the lines are better resolved with the optimized arrays. The optimized arrays also have significantly better depth resolution compared to the conventional arrays.

Characterization of a Proposed Quarry Site using Multi-Electrode Electrical Resistivity Tomography

“…The 2-D ERT survey was carried out with ABEM SAS4000 Terrameter together with a selector, ABEM with the application of pole-dipole electrodes array technique. The RES2DINV software was used to modelled the resistivity field data (Loke et al 2015(Loke et al , 2014(Loke et al , 2013Rucker et al 2010;Wilkinson et al 2013).…”