Cross-hole resistivity tomography using different electrode configurations

This paper investigates the relative merits and effectiveness of cross-hole resistivity tomography using different electrode configurations for four p opular electrode arrays: pole-pole, pole-bipole, bipole-pole and bipole-bip ole. By examination of two synthetic models (a dipping conductive strip and a dislocated fault), it is shown that besides the popular pole-pole array, some specified three- and four-electrode configurations, such as pole-bipo le AM-N, bipole-pole AM-B and bipole-bipole AM-BN with their multispacing c ross-hole profiling and scanning surveys, are useful for cross-hole resisti vity tomography. These configurations, compared with the pole-pole array, m ay reduce or eliminate the effect of remote electrodes (systematic error) a nd yield satisfactory images with 20% noise-contaminated data. It is also s hown that the configurations which have either both current electrodes or b oth potential electrodes in the same borehole, i.e. pole-bipole A-MN, bipol e-pole AB-M and bipole-bipole AB-MN, have a singularity problem in data acq uisition, namely low readings of the potential or potential difference in c ross-hole surveying, so that the data are easily obscured by background noi se and yield images inferior to those from other configurations.