A new method for the automatic interpretation of Schlumberger and Wenner sounding curves

Abstract

A fast iterative method for the automatic interpretation of Schlumberger and Wenner sounding curves is based on obtaining interpreted depths and resistivities from shifted electrode spacings and adjusted apparent resistivities, respectively. The method is fully automatic. It does not require an initial guess of the number of layers, their thicknesses, or their resistivities; and it does not require extrapolation of incomplete sounding curves. The number of layers in the interpreted model equals the number of digitized points on the sounding curve. The resulting multilayer model is always well‐behaved with no thin layers of unusually high or unusually low resistivities. For noisy data, interpretation is done in two sets of iterations (two passes). Anomalous layers, created because of noise in the first pass, are eliminated in the second pass. Such layers are eliminated by considering the best‐fitting curve from the first pass to be a smoothed version of the observed curve and automatically reinterpreting it (second pass). The application of the method is illustrated by several examples.

Inversion of 2-D DC resistivity data using rapid optimization and minimal complexity neural network

“…Although the error range lies 0.1-0.2, it is considered very low compared with the other conventional inversion techniques i.e. radial error of ≤5% (Zohdy, 1989).…”

Inversion of Schlumberger resistivity sounding data from the critically dynamic Koyna region using the Hybrid Monte Carlo-based neural network approach

“…Inverse modeling, in contrast starts with the data and a general principle or a model, in which the model parameters are estimated by minimizing the error/misfit function set up between the data and model parameters (Menke, 1984). During the past decades researchers have made several attempts to solve the resistivity inverse problems (Ghosh, 1971;Zohdy, 1989;Macias et al, 2000;Qady and Ushijima, 2001;Singh et al, 2005;Ekinci and Demirci, 2008). However, these approaches have some common drawbacks.…”

Hydrology and water quality of the Beaver Dam Wash area, Washington County, Utah, Lincoln County, Nevada, and Mohave County, Arizona

“…Resistivity values as a function of depth are derived from the sounding curve with the aid of digitalcomputer programs (Zohdy, 1989;Zohdy and Bisdorf, 1989). Maximum electrode half-spacings for this survey ranged from 1,400 to 12,000 ft.…”

“…The resistivity values from a series of soundings along a line of profile can be combined to form a resistivity cross section (Zohdy, 1993). The cross section can then be interpreted in terms of changes in geohydrologic properties along the line of profile.…”