Treatment of contaminated oil produced by oil and gas wells

A method of treating a contaminated oil, the method comprising:

• a) preparing a brine solution;
• b) adding ozone to the brine solution to produce ozonated brine solution;
• c) adding a volume of ozonated brine solution to a volume of the contaminated oil;
• d) adding a coagulant to the volume of contaminated oil;
• e) adding a surfactant to the volume of contaminated oil;
• f) mixing the volumes of contaminated oil and ozonated brine solution, the coagulant, and the surfactant at a shear rate sufficiently high so as to cause formation of an emulsion of the contaminated oil and the brine solution;
• g) adding an anionic polymer to the emulsion and causing the emulsion to separate into an aqueous brine liquid phase and an oil liquid phase;
• h) separating the brine liquid phase from the oil liquid phase;
• and
• i) separating at least one contaminant from the oil liquid phase to produce a volume of purified oil.