Abstract:

A novel flocculant combination was developed for the treatment of fracturing flowback fluid of Linxing coalbed methane field, with polysilicic acid polymerized iron sulfate as the coagulant and acrylamide and acrylic acid-1,2-ethylenetriammonium chloride copolymer as the coagulant aid. The optimal conditions for flocculation treatment of gas layer fracturing flowback fluid were optimized and screened, and the flocculation mechanism was analyzed. The results showed that the best flocculation effect was achieved when the mass concentration of the agent was 300-400 mg/L, the pH was 7.5-8.5, the temperature was 25-35 ℃, the mixing strength was 1 300-1 500 s^-1, and the flocculation time was 20-30 s. Under optimized conditions, the novel flocculant combination was applied to the Linxing coalbed methane backflow liquid treatment station. The suspended solids mass concentration in the effluent was stabilized at 6-8 mg/L, the oil mass concentration was stabilized at 3-5 mg/L, and the median particle size was stabilized at 1.4-1.7 μm. The effluent quality met the reinjection water control indicators at reservoir air permeability of [0.5, 2.0) μm² of the Technical Requirements and Analysis Methods for Water Quality Indicators in Clastic Rock Reservoirs (SY/T 5329-2022). The effluent could be directly reinjected into the ground. The novel flocculant combination has broad prospects for application and promotion.

Key words: fracturing flowback fluid, flocculation, reinjection

摘要：

以临兴煤层气压裂返排液为研究对象，开发了以聚硅酸聚合硫酸铁为混凝剂，丙烯酰胺与丙烯酸-1，2-亚乙酯基三甲基氯化铵共聚物为助凝剂的新絮凝剂组合，优化筛选了煤层气压裂返排液絮凝处理的最佳工艺条件，并对絮凝机理进行了分析。结果表明，药剂投加质量浓度为300~400 mg/L，pH为7.5~8.5，温度为25~35 ℃，混合强度为1 300~1 500 s^-1，絮凝作用时间为20~30 s时絮凝效果最好。在优化的工艺条件下将新絮凝剂组合应用于临兴煤层气返排液处理站，出水悬浮物质量浓度稳定在6~8 mg/L，油质量浓度稳定在3~5 mg/L，粒径中值稳定在1.4~1.7 μm，出水水质完全满足《碎屑岩油藏注水水质指标技术要求及分析方法》（SY/T 5329—2022）储层空气渗透率在［0.5，2.0） μm²地区回注水控制指标，可直接回注到地层，具有广阔的应用推广前景。

关键词: 压裂返排液, 絮凝, 回注

CLC Number: 

• X703.5

• X741