Patent ID: 8330466

Claim:
A method used in electrical investigation of geological formations surrounding a borehole comprising: determining (S 1 ) a grid of iso-parameter lines (GR) in a two-dimensional plane, the parameter being an electrical parameter characterizing the geological formation, injecting in a localized manner a survey current (I S ) into a selected zone (SZ) of the geological formations (GF) surrounding the borehole (BH), and measuring (S 2 ) a measured value of a quantity characterizing the electrical parameter of the selected zone based on the survey current, and interpolating (S 3 ) an interpolated electrical parameter value of the selected zone (SZ) based on the measured value and the grid of iso-parameter lines (GR) estimating a formation permittivity value by interpolation based on the measured value and iso-formation permittivity curves, the iso-formation permittivity curves being lines that intersect the iso-resistivity-lines in a high resistivity region, the high resistivity region being the region where measurements are more affected by the geological formations permittivity than by a ratio p, wherein p is a ratio between a mud permittivity and a standoff.