A study of a two-dimensional resistivity and IP array

Advances in inexpensive data acquisition technology allow us to collect up to 256 channels of data simultaneously at a total sampling rate of 100 kHz. With so many channels available, it is possible to set up a two-dimensional (2D) receiver array for resistivity, induced polarization (IP) and self-potential (SP) surveys. A 2D array would be best suited for environmental and engineering applications, where the requirement for detail suggests that measurements be taken at relatively dense station spacings in a small area, and the set up procedure is thus relatively straightforward. One of the main questions for a 2D array is the optimum location of the transmitter electrodes. This paper investigates this problem with the use of 3D numerical modeling and with two field experiments. According to our modeling and field experiment results, a gradient 2D array is the most efficient array for resistivity and IP mapping. One set of transmitter electrodes could be enough to determine the horizontal position of a target and the strike direction of a geological structure. In addition, the 2D array also gives excellent SP data because it eliminates time-varying noise from the measurements.