The use of supercritical fluid extraction for the treatment of oil contaminated drilling waste

Supercritical fluid extraction (SFE) with CO2 is a promising new technique to treat drilling waste. In this research, two types of drilling waste were investigated: centrifuge underflow cuttings and invert cuttings. The extraction conditions studied were from 8.96 MPa to 15.2 MPa for pressure and from 40°C to 60°C for temperature.; Within the conditions tested, the suggested operating conditions were 14.5 MPa and 40°C. Under these conditions, the treated cuttings appeared dry, powder-like, and light in color. The high extraction efficiencies indicated that the SFE process was able to reduce the oil content from 19.4% to approximately 0.3%, which is below regulatory guidelines.; Good mixing by a ribbon blender led to high extraction efficiencies. The use of high water contents (1:1 drilling wastewater ratio) and drying agents did not affect the extraction efficiency.; The results are helpful to determine the loading ratio of cuttings in SC CO2 at larger scales.