Analysis of Response Characteristics in Borehole Electrical Resistivity Surveys and Their Applications

Abstract

The direct current electrical resistivity survey or electrical resistivity tomography (ERT) is a geophysical exploration technique employed in various fields, including mineral exploration, environmental studies, and subsurface safety assessments. ERT, primarily conducted at the surface, can also be conducted between adjacent boreholes to yield high-resolution subsurface images at greater depths. Compared to surface exploration methods, cross-hole ERT employs distinct electrode configurations with varying sensitivities, making it crucial to consider these differences in electrode configuration or measurement environment conditions. This study elucidates electrode configurations and subsequently analyzes the characteristics of cross-hole ERT data for each electrode configuration. Following this, we explore the peculiarities stemming from borehole ERT data. We also describe distortions in ERT data caused by survey geometry and provide an examination of potential solutions to mitigate these distortions. Additionally, we introduce several case studies involving borehole ERTs.