页岩气开发水基钻屑中含油率的测定方法研究

以页岩气开发过程中产生的废弃水基钻屑中含油率测试方法为研究对象，采用超声协同萃取法对模拟水基钻屑中油类污染物萃取，以四氯化碳和四氯乙烯为萃取剂，考察在不同的萃取条件（温度、超声功率、时间、液固比）下萃取，利用红外测油仪测量时对其含油率的影响。结果表明，在超声协同萃取的温度为25 ℃，功率为120 W，时间为20 min，液固比为4 mL/g时，两种萃取剂对模拟水基钻屑（含油率610%）中萃取后测量其含油率都在9.6%以上，相对误差<5%，四氯化碳的萃取效率高于四氯乙烯；对页岩气开发平台现场的废弃水基钻屑与模拟水基钻屑中的含油率进行对比测量，并计算其加标回收率和相对标准偏差R_SD，两者R_SD<5%，加标回收率高。两类萃取剂在相同的萃取条件下对水基钻屑中含油率测试结果变化规律一致，可选择对环境危害较小的四氯乙烯作为水基钻屑中含油率测试的萃取剂，测试结果精度满足测试要求。

Determination Method of Oil Content of Water-based Drilling Cuttings in Shale Gas Development

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.