Experimental study on treatment of high-oil sludge containing polymer by thermochemical cleaning and countercurrent extraction

In order to meet the demand of resource utilization and harmless treatment of high-oil sludge containing polymer, a comprehensive treatment process with “thermochemical cleaning and countercurrent extraction” as the core was developed. The removal of crude oil from high-oil sludge containing polymer of one marine drilling platform by thermochemical cleaning and countercurrent extraction was studied experimentally. A domestic brand of washing powder was used as cleaning agent during the thermochemical cleaning. Results showed that the optimum conditions for thermochemical cleaning was temperature of 65 ℃, the liquid-to-solid mass ratio of 3:1, the cleaning time of 25 min, and the stirring rate of 450 r/min. After thermochemical treatment, the dry base oil content of oil sludge decreased from 62.0% to 25.4%, and the removal rate could reach 59.0%; moreover, the oil sludge after treatment showed good dispersion in the subsequent countercurrent extraction process. The dry base oil content of solid after “thermochemical cleaning and countercurrent extraction” was 1.7%, which perfectly met the control standards of Technical Requirements for Comprehensive Utilization and Pollution Control of Oil-bearing Sludge in Oil and Natural Gas Exploitation (SY/T 7301-2016), and the mineral oil could be delivered to the refinery for recycling.