Cyclone Oil Desorption Technology for the Disposal of Oil-Based Mud Cuttings

Abstract

Summary With the flourishing shale gas exploitation producing more oil-based mud (OBM) cuttings, the hard-to-treat hazardous wastes heavily burden the local environment. However, the problems of treating OBM cuttings, such as huge energy consumption, tremendous treatment costs, and high risk of secondary contamination, still remain unsolved with the current treatment technologies, such as thermal desorption, incineration, and chemical extraction. In this study, we introduce a new method and equipment based on cyclone desorption to recover oil from OBM cuttings. The technological process includes viscosity reduction in heated gas, cyclone deoiling, condensation and recycling of the exhaust, and separation of oil and water in the coalescer. Based on the analysis of the physicochemical properties and the oil distribution inside the OBM cuttings samples collected from the Chongqing shale gas field, we designed this cyclone oil desorption technology and built the pilot-scale equipment to conduct the deoiling experiments. The results showed that the deoiling efficiency of OBM cuttings improved as the processing time increased. To be precise, after 2.7 seconds of treatment, the oil content of the cuttings samples fell sharply from 17.9 to 0.16%, which is about one-half of the maximum allowable oil content in pollutants of 0.3%, specified in the national standard (GB 4284-84 1985) promulgated by the People’s Republic of China. The foundation of the technology is that the particles have a high-speedself-rotation (more than 30,000 rad/s) coupled with a revolution in the cyclone in which a generated centrifugal force removes the oil from the pores of the particles. This process is purely physical and involves no phase change of the oil, so it is free of chemical addition and high heating temperature. The application of this newly developed cyclone oil desorption technology is expected to lower the treatment costs, enhance the processing efficiency, contribute to the energy development, and eventually benefit the local environment where the shale gas exploitations take place.

Environmental Risk Analysis Based on Characterization of Ground Oily Sludge

“…The composition of oily sludge is shown in Table 1. The experimental results show that the oil content of oily sludge is 10.3%, which is 34 times the maximum oil content of 0.3% allowed by Chinese standards, 10 times that of the American standard, 5 times the Canadian standard, 21 times the French wetland standard, and 5 times the French dryland standard [38]. Based on the fact that the oil phase of oily sludge contains a lot of petroleum hydrocarbon pollutants, if it is released indiscriminately, it will cause serious pollution to the environment.…”