A full-range gradient survey for 2D electrical resistivity tomography

In this paper, we propose an enhanced version of the multi-gradient measurement technique, called full-range gradient survey, for 2D electrical resistivity tomography. To demonstrate its effectiveness, we conducted numerical simulations and field experiments to highlight the advantages of the new data-acquisition technique on the traditional electrode arrays and the original multi-gradient measurement technique. A comparison of the imaging capabilities of the full-range gradient technique with the dipole–dipole, Schlumberger and multi-gradient shows that the former inherits all the advantages of the multi-gradient technique as well as the sensitivity of the traditional three- and four-electrode arrays. The new survey technique has a better pseudo-section coverage, a much smaller geometrical factor, and less noise contamination than the dipole–dipole survey. It significantly improves the subsurface images of the Schlumberger and original multi-gradient data. The numerical and field experiments both demonstrate that the full-range gradient survey can be an alternative to all the traditional electrode arrays and original multi-gradient surveys of 2D electrical resistivity tomography to obtain better quality and higher resolution images of near-surface targets.