Treatment of Oil-Based Drilling Waste Using Supercritical Carbon Dioxide

Oil-based drilling fluids are essential for challenging drilling operations. However, their use requires costly handling, treatment and diposal. Supercritical fluid extraction is herein investigated as a novel technology to treat this waste. Supercritical fluid extraction employs a substance above its critical temperature and pressure as a solvent. In this state, the substance has both liquid- and gas-like properties that can be controlled by the pressure and temperature of the extraction process. In this paper, results of studies using supercritical carbon dioxide to remove the base oil from drilling waste are presented. Current work investigates the extraction of hydrocarbons (i.e. base oil) from a synthetic oil-based centrifuge underflow drilling waste. Extraction efficiencies as high as 98% have been observed. Additionally, results of both past and current studies indicate that the hydrocarbons are unchanged by the extraction process and that they may be recovered and potentially reused.