DETECTING LATERAL RESISTIVITY INHOMOGENEITIES WITH THE SCHLUMBERGER ARRAY

A method of detecting lateral resistivity inhomogeneities with a multi -electrode cable for the Schlumberger array is presented. Using such a cable system, two dipole-dipole soundings are gathered in addition to the Schlumberger sounding at each point. Offset differences calculate d from the dipole-dipole data give qualitative information about later al resistivity inhomogeneities. Results from 1D modelling can give qua ntitative information about the 2D resistivity distribution since the dipole-dipole soundings are made to either side of the Schlumberger so unding point. Examples from two different locations in Norway are show n. At Reinoya, northern Norway, a dipping layer, confirmed by refracti on seismic data, was identified. In a sedimentary basin with a contami nation plume at Haslemoen, southern Norway, the method has revealed la teral variations in resistivity. In both cases, the Schlumberger sound ings could be fitted with a 1D resistivity model.