Biodegradation of Oil on Drilled Cuttings

Drilled cuttings from offshore petroleum exploration are discarded to sea. Oil based drilling fluids leave oil on cuttings that may become environmentally toxic. Successful biological separation of oil and cuttings was accomplished by addition of nitrogen and phosphorus to seawater in completely mixed aerobic batch reactors at 10 and 20°C. Substantial biodegradation in flow-through aquaria, however, was not accomplished. Both retort distillation and solvent extraction using dichloromethane in a Soxhlet apparatus separated reproduceable quantities of hydrocarbons from cuttings. The oil was characterized by glass capillary gas chromatography and medium pressure liquid chromatography.