Rheology manipulation enabled low-temperature cyclone separation for oil-based drill cuttings: economical and efficient recovery of high-quality oil at industrial scale

Abstract

Oil-based drill cuttings (OBDC) are typical hazardous wastes generated during the process of oil and gas drilling, which contain the oil-based drilling fluids and the drill cuttings. It is important to effectively separate oil from the OBDC in the viewpoint of waste treatment and oil recovery. Herein, we reported that manipulating the rheological properties of OBDC enabled the recovery of high-quality oil by low-temperature cyclone separation. We found that calcium oxide (CaO) was an effective modifier to tune the rheological properties of OBDC, which provided a “V” shape change of shear stress strength along with the increase of CaO dosage, showing the lowest shear stress strength at 20 wt% of CaO. The addition of CaO also improved the oil repellency properties of OBDC, which promoted the separation of oil from the OBDC. The OBDC containing 20 wt% of CaO was then efficiently separated by the cyclone that created the cyclonic flow to enable the high-speed rotation and spin of OBDC particles, which promoted the intensive collision and compression of the OBDC particles, thus realizing the high-performance separation of oil steam from OBDC particles at the low temperature of ∼ 280 °C. The separated OBDC exhibited the oil content lower than 0.1 wt%, and the recovery rate of oil was high up to 95 %. The combustion heat of the recovered oil was comparable to that of diesel. We therefore provided a promising approach for the recovery of high-quality oil from the OBDC at low temperature.