TRIGEO has carried out a series of surveys for Mellitah Oil & Gas B.V., Libyan Branch for the characterization of an oil plant, in Sinawin – Libya. 20 Geoelectric sections, 160 SERT ( Soil Electrical Resistivity Test) and 160 Down Hole seismic surveys have been carried out. These surveys permitted the characterization of materials depending on the variation in depth of the compression and shear seismic waves speed, through the progress of resistivity values of the soil. The SERT measurements, related to the resistivity values obtained, made it possible to evaluate the degree of corrosiveness in the first meters of the inspected soils. Generally a low resistivity value indicates a high degree of corrosiveness.