| Supercritical carbon dioxide (SC CO2) treatment of oil contaminated drill cuttings is a promising new technology. In this work, supercritical carbon dioxide was successfully used to extract oil from raw centrifuge-underflow oil-based mud (OBM) drill cuttings obtained from active drilling sites. Extraction experiments were conducted at several conditions of temperature and pressure ranging from 35 to 60°C and 8.3 to 17.2 MPa, respectively, with a 45-minute single cycle extraction and magnetic stir bar mixing. The raw and extracted cuttings' petroleum hydrocarbon (C10--C32) contents were determined by gas chromatography/flame ionization detection (GC/FID). An optimal single cycle extraction efficiency of 90% was obtained at 60°C and 12.4 MPa, reducing the cuttings petroleum hydrocarbon content from 17.19% to 1.76%. At the same conditions, 90-minute double cycle extraction increased the efficiency to 97%, reducing the cuttings petroleum hydrocarbon content to 0.55%. SC CO2 recovers the expensive drilling mud oil, which can be reused in the drilling operation, while leaving "clean" and "dry" cuttings. |
