西北油田塔里木地区水基钻井液体系环保控制指标研究

Research on environmental control index of water-based drilling fluids in Tarim area of Northwest Oilfield

关键词:  水基钻井液  环保  污染控制指标  BOD  重金属离子

Key words:  water-based drilling fluid  environmental protection  pollution control index  BOD  heavy metal

摘要:

目前,国内尚未制定单独的钻井液环保标准,造成钻井液体系环保性优化的方向不明确。通过调研国内现行的各种水质及土壤环保排放标准,针对西北油田在用的水基钻井液及处理剂的COD值、BOD值、生物毒性、重金属离子(Hg、Cd、总Cr、As、Pb)以及苯并芘等环保控制指标进行检测评价。依照GB 8978-1996《国家污水综合排放标准》和《农用地土壤环境质量标准》(三次征求意见稿)两个标准进行评价。评价结果表明:西北油田水基钻井液BOD值和COD值为30～3 000 mg/L,苯并芘质量浓度大于0.000 3 mg/L,远超GB 8978-1996的三级标准,而钻井液处理剂这3项指标达标率近100%；重金属离子部分达到GB 8978-1996的三级标准,其中Cd、总Cr和Pb是主要的超标项。建议在实际指标控制中,针对钻井液体系和处理剂分开制定相应的排放标准,并加强钻井液体系及处理剂尤其是润滑剂、降滤失剂等的环保指标检测,为后期研发环保钻井液体系和检测标准奠定技术基础。

Abstract:

Since there is no specialized environmental standard for drilling fluid in China, the direction of optimizing the environmental protection in drilling fluid system is ambiguous. In this paper, we investigated the COD, BOD, biological toxicity, heavy metals (Hg, Cd, Cr, As, Pb) and the content of benzopyrene and other environmental control indicators of both water-based drilling fluid and treating agents in northwest oilfields for testing and evaluation. According to the two standards of "National Integrated Wastewater Discharge Standard"(GB 8978-1996) and "Soil Environmental Quality Standard for Farmland", the evaluation results showed that the BOD and COD contents of water-based drilling fluid in Northwest Oilfield were between 30-3000 mg/L, and benzopyrene content was more than 0.0003 mg/L, far exceeding the three criteria of GB 8978-1996. Besides, the compliance rate of the these three indicators for the drilling fluid treatment was nearly 100%; heavy metals (Hg, Cd, Cr, As, Pb) partly achieved Level 3 in the criteria of GB 8978-1996, of which cadmium, chromium and lead are the major concerns. It recommended that in the actual control of indicators for the drilling fluid system, appropriate emission standards should be set respectively and the drilling fluid system and treatment agents, especially for lubricants, fluid loss and other indicators of environmental protection testing should be strengthened, laying the technical foundation for developing the environmentally-friendly drilling fluid system and testing standards in the future.