Abstract:

The produced water of Dongsheng gas field was mixed with fracturing flowback fluid，resulting in high COD of produced water，complex water quality and reduced treatment efficiency of water treatment system. Based on the existing produced water treatment process and reagent system，sodium hypochlorite was selected as oxidant to degrade high molecular substances to improve the subsequent flocculation and sedimentation effect. The reagent system for treating typical produced water containing fracturing flowback fluid was formulated as follows：oxidant 700 mg/L，pH regulator 400 mg/L，coagulant 450 mg/L，organic flocculant 0.6 mg/L. After treatment，the suspended solids content was 4.67 mg/L and the oil content was 3.81 mg/L，meeting the reinjection requirements. It is recommended to add oxidant into the oil removal tank of the treatment plant. The reconstruction work is small and can basically meet the requirements of complex produced water treatment. For the new water treatment process，it is recommended to add new oxidation reactor and adopt skid mounted design.

Key words: produced water, fracturing flowback fluid, flocculation sedimentation, oxidant, sodium hypochlorite

摘要：

东胜气田采出水中混入了压裂返排液，造成采出水COD偏高，水质趋于复杂，水处理系统处理效率降低。基于现有采出水处理流程及药剂体系，优选次氯酸钠为氧化剂，降解高分子物质，以提升后续絮凝沉降效果。制定了处理典型含压裂返排液采出水的药剂制度为：氧化剂700 mg/L+pH调节剂400 mg/L+混凝剂450 mg/L+有机絮凝剂0.6 mg/L。处理后悬浮固体（SS）为4.67 mg/L，含油质量浓度为3.81 mg/L，满足回注要求。针对现有流程改造，推荐在处理厂除油罐中加入氧化剂，改造工程量小，可基本满足复杂采出水处理要求。针对新建水处理流程，推荐新增氧化反应器，采用撬装化设计。

关键词: 采出水, 压裂返排液, 絮凝沉降, 氧化剂, 次氯酸钠

CLC Number: 

• X741