The biological activity of oil extracted from green algae has long been known, but evaluation of bimolecular activities contained in this oil on an industrial scale, especially in the oil industry, was the objective of our research project. The first stapes of this study is to extract the essential oil from green algae marine Ulva Lactuca in our region, obtained by extraction/purification method based on hydro distillation and methanol extraction, the work performed at the laboratories of Sonatrach (SH/DTD/AUI/CEM). The second stapes is to evaluate the potential of these algae extracts on microbiologically influenced corrosion. After chemical-physic characterization of two bio naturals products A and B, we test their effectiveness as a bactericide on bacterial corrosion of carbon steel in water contained sulfate reducing bacteria by electrochemical analysis techniques (Open-circuit potential/OCP and Electrochemical Impedance Spectroscopy/EIS).