The petroleum industry is responsible by the generation of wastes that are both toxic and radioactive, sometimes called mixed waste. The toxicity is due to the presence of hydrocarbons and sulfur and the radioactivity is the result of the leaching of thorium and uranium daughters present in the oil-producing formation and their transport by the extracted fluids to the production rigs. Because of the presence of these radioactive materials of natural origin, this waste is named TENORM (Technologically Enhanced Naturally Occurring Radioactive Material). The main radionuclides present are 210Pb, 224Ra, 226Ra and 228Ra. In Brazil, the offshore platforms cannot dispose this waste by reinjection in wells because federal law prohibits disposal of radioactive waste in seawaters or seabed. The waste is, therefore transported to land and stored. This work aims at investigating a method of decontaminating the oil sludge by using surfactant that can increase the removal efficiency of the radionuclides. After a successful treatment, the decontaminated waste can be disposed of as non-radioactive industrial waste in a licensed facility and the concentrated radioactive material can be treated as radioactive waste, decreasing significantly the costs of management and improving safety.