作者：孔燕燕1, 姜富川2, 邓宇1
作者单位：1. 中国石油天然气集团公司川庆钻探工程有限公司钻井液技术服务公司, 四川 成都 610000;
2. 中国石油天然气集团公司西南油气田公司生产运行处, 四川 成都 610000
关键词：页岩气;COD测定;标准加入重铬酸盐法
摘要：
以页岩气压裂返排液（高氯废水）中COD（化学需氧量）含量的测试方法为研究对象，考察测试体系中硫酸汞加量为0.2 g时能掩蔽的Cl-浓度，以此确定其稀释倍数，再结合相关标准对其未知的COD含量采用标准加入重铬酸盐法测定。结果表明，对长宁某平台页岩气压裂返排液稀释10倍后（使Cl-含量在2 000 mg/L以下），硫酸汞加量为0.2 g时，通过测试绘制标准曲线得到页岩气压裂返排液中COD含量为1 065 mg/L，测定结果相对误差≤±5%；对页岩气开采过程中其他废水COD测试适用性分析得出：标准加入重铬酸盐法测试结果的相对误差比国标重铬酸盐法小，仅为1.26%。通过研究标准加入重铬酸盐法对水样（特别是成分较为复杂的废水）中低浓度COD测量时，可屏蔽溶液中其他还原性离子对测试过程的影响，保证测试结果的准确性。
Study on COD of flowback and produced water in shale gas field by standard addition method
KONG Yanyan1, JIANG Fuchuan2, DENG Yu1
1. China National Petroleum Corporation Chuanqing Drilling Engineer Co., Ltd., Drilling Fluid Technology Service Company, Chengdu 610000, China;
2. Production and Operation Department of Southwest Oil and Gas Field Company of China National Petroleum Corporation, Chengdu 610000, China
Abstract: This study is focus on the method of COD for flowback and produced water in shale gas field. To determine the dilution, Cl- concentration was measured when it can be masked under 0.2 g mercury sulfate in the system, combined with the relevant standards to acquire the COD by standard addition of dichromate method. The results showed that the COD was 1 065 mg/L and the relative error of the measurement results is less or equal to ±5% according to the standard curve when the flowback and produced water was diluted 10 times to assure the Cl- concentration was blow 2 000 mg/L and 0.2 g mercury sulfate was added. The applicability analysis of discharged water from the other operation in shale gas field showed that the relative error of the standard addition of the dichromate test results is smaller than the national standard chromate method, which is only 1.26%. It suggested that the test results for discharged water when using the standard addition of the dichromate method to measure the low concentration of COD, especially those with complex composition, was reasonable, and the effect of other reducing ions in the solution can be shielded on the test process.
Keywords: shale gas;COD measurement;standard adding dichromate method
2019, 45(9):65-69 收稿日期: 2019-01-15;收到修改稿日期: 2019-03-05
基金项目: 中国石油天然气集团公司重大工程技术现场试验项目（2018F-21）；钻井液技术服务公司项目（ZJY2018-4）
作者简介: 孔燕燕(1984-),女,四川遂宁市人,工程师,主要从事钻井液技术研究与应用工作
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