Treatment of Non-Aqueous Drilling Waste Using Supercritical Carbon Dioxide

Abstract

Non-aqueous drilling fluids, both synthetic and oil based, are essential in challenging drill operations. However, their use requires costly handling, treatment and disposal. Supercritical fluid extraction is 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 non-aqueous fluids from drilling waste are presented. Current work investigates the extraction of hydrocarbons from centrifuge underflow synthetic based drilling waste. Although the extraction process is not yet fully optimized, extraction efficiencies as high as 98% have been observed. Additionally, results of both past and current studies indicate that non-aqueous drilling fluids are unchanged by extraction process and that the recovered hydrocarbons may potentially be collected and reused.