通过分析某地区非常规页岩气碳酸岩地层酸化压裂返排液水质，对现有国内酸化压裂返排液处理技术进行比选和方案论证，提出了“混掺沉降+Fenton氧化破胶+均质混凝+气浮+过滤”五步水处理工艺。通过现场处理效果验证，出水水质指标分别为pH值6～9，含油量≤5 mg/L，悬浮物≤15 mg/L，平均腐蚀率≤0.06 mm/a，各项指标稳定均满足油气田回注水标准要求（Q/SY TZ 0466—2016《生产回注水质指标》中碳酸盐岩回注水质主要控制指标和SY/T 5329—2022《碎屑岩油藏注水水质指标技术要求及分析方法》中储层空气渗透率≥2.0的V级水质标准），污泥产生量由3.9%降低至1.8%，为非常规页岩气开发酸化压裂返排液回注处理提供参考。

By analyzing the water quality of flowback fluids from acid fracturing in carbonate formations of shale gas reservoirs, this study evaluates existing domestic treatment technologies and proposes a five-step process: mixed sedimentation, Fenton oxidation for gel breaking, homogeneous coagulation, air flotation, and filtration. Field tests show treated effluent meets reinjection standards: pH 6-9, oil content≤5 mg/L, suspended solids≤15 mg/L, average corrosion rate≤0. 06 mm/a. All indicators stably met reinjection standards the Main Control indicators for the water quality of carbonate rock reinjection in Q/SY TZ 0466—2016 “Water Quality Standard of Olifield Produced Water for Injection”,Grade V Water Quality Standard for Reservoir Air Permeability ≥ 2. 0 in SY/T 5329—2022 “Water Quality Specification and Practice for Analysis of Oilfield Injecting Water in Clastic Reservoirs”. Sludge generation was reduced from 3. 9% to 1. 8%. The results provide a reference for reinjection treatment of flowback fluids in unconventional shale gas development.