Abstract: Taking the determination method of the oil content in waste water-based drilling cuttings in shale gas development for research object, tetrachloride and tetrachloroethylene are chosen as extraction agent in the extraction of oily substances in the simulated water-based drilling cutting under different extraction conditions (temperature, ultrasound power, reaction time, liquid/solid ratio) using ultrasound assisted extraction method; the oil content is analyzed by infrared oil content analyzer. The experimental results indicate that with the temperature of 25 ℃, the ultrasound power of 120 W, the reaction time of 20 min, and the liquid/solid ratio of 4 mL/g, the oil content reach above 9.6% with low deviations (<5%). The extraction efficiency of carbon tetrachloride is higher than that of tetrachloroethylene. By measuring the the oil content from on-site and simulated waste water-based drill cuttings and calculating the mark-up recovery and relative standard deviations (R_SD) for two types of samples, we get the mark-up recovery between 95%~105%, and the R_SD was less than 5%. Under the same extration condition, the result of test shows that oil content in water-based drilling cuttings extracted by the carbon tetrachloride coincide with that of tetrachloroethylene. Therefore, tetrachloroethylene, which is less harmful to the environment, was selected as the extraction agent for oil content test in water-based drilling cuttings, and the test results meet the test requirements.

Key words: water-based drilling cuttings, ultrasound assisted extraction, oil content, infrared oil measurement, mark-up recovery