Treatment of oil-based drilling cuttings by floatation-advanced oxidation two-step process.

In this paper, a floatation-advanced oxidation two-step process was proposed for deep oil removal of oil-based drilling cuttings (OBDC). In the first stage, a novel and simple degreasing solution was prepared and most of the base oil contained by OBDC was removed by flotation; in the second stage, the oil content of OBDC was further reduced by combined ultrasound + ozone (US + O3) advanced oxidation. The recommended degreasing solution was a mixture of methanol, ammonium chloride, and water with a mass ratio of 1.48.1 : 0.25. The best flotation process was as follows: a mass ratio of OBDC to degreasing solution of 1 : 10, stirring speed of 400 rpm and N2 flotation with a flow rate of 400 mL min-1 for 60 min. The oil content of OBDC can be reduced from 14.57% to 1.42% after flotation treatment and the degreasing solution can be reused more than five times. The optimal process of US + O3 advanced oxidation was as follows: a mass ratio of OBDC to water of 1 : 10, ultrasonic power of 1000 W, and an ozone flow rate of 4.0 L min-1 for 100 min. The oil content of OBDC can be reduced from 1.42% to 0.14% after US + O3 treatment at room temperature. The results of this paper provide a new method and idea for OBDC treatment.

Ultrasonication-flotation-advanced oxidation tertiary treatment of oil-based drilling cuttings.

The treatment of oil-based drilling cuttings (OBDCs) with high oil content is difficult. In this study, a tertiary treatment of ultrasonication-flotation-advanced oxidation for treating OBDCs with a high oil content of 20.10 wt% was proposed for the first time. All stages of the treatment processes were optimised. The recommended parameters for ultrasonication at room temperature were a mass ratio of OBDCs to the degreaser of 1:8, an ultrasonication power of 600 W and treatment time of 30 min. After the ultrasonication treatment, the oil content of the OBDCs decreased from 20.10 wt% to 5.00 wt%. Flotation was performed at room temperature with a mass ratio of OBDCs to the degreaser of 1:10, a stirring speed of 400 rpm, an aeration head aperture of 3 µm and airflow rate of 400 mL/min under N2 injection for 60 min. After the flotation treatment, the oil content of the OBDCs decreased from 5.00 wt% to 2.01 wt%. Advanced oxidation was performed at room temperature with a mass ratio of OBDCs to water of 1:10, 3.57 wt% sodium persulphate in water, 4.17 wt% ferrous sulphate heptahydrate in water and ultrasonication power of 1000 W for 100 min. Following the advanced oxidation treatment, the oil content of the OBDCs decreased from 2.01 wt% to 0.58 wt%. The results of this study provide a new method and idea for treating OBDCs with high oil content.