Resistivity methods with application to Planillas Geothermal Field, Mexico

Abstract

The depth of penetration of Schlumberger soundings is controlled by the shortest distance between the current electrode and the potential electrode (S-P). This together with the application of the finite potential electrodes separation over a resistivity distribution with high contrasts between layers and lateral resistivity variations near the surface at the sounding site, causes converging and constant shifts of the different segments of the apparent resistivity curve. These shifts, if not correctly treated will lead the interpretation astray. Therefore the theory of one-dimensional interpretation of Schlumberger soundings is presented in this report in some details in order to understand the reasons for these shifts and to make an appropriate use of two computer programs for one-dimensional interpretation. A two-dimensional interpretation program, which takes the topography into account, is also discussed. Schlumberger soundings from Planillas Geothermal Field, Mexico were interpreted one- and two-dimensionally. This resulted in the delineation ...