氧化破胶-絮凝过滤工艺降黏处理压裂返排液的研究

针对压裂返排液黏度较大、有机污染物含量高和处理难度大的特点,采用以Fenton试剂为氧化剂,聚合氯化铝为絮凝剂的氧化破胶-絮凝过滤工艺对其进行降黏处理和回收利用,并以黏度为指标,考察了Fenton试剂中H_2O_2(30%)、FeSO_4(0.5 mol·L~(-1))添加量及溶液pH、氧化破胶反应时间、絮凝剂种类和用量对降黏效果的影响。结果表明,对于100 mL黏度为16 m Pa·s的油田压裂返排液,当溶液pH为3.0,Fenton试剂中H_2O_2和FeSO_4添加量分别为0.48 mL和0.3 mL,反应时间为50 min时,氧化破胶效果最佳;氧化破胶后的溶液再经0.5 g聚合氯化铝絮凝过滤处理后,黏度可以降至1.1 m Pa·s,溶液中的大部分污染物也被除去,可以实现循环回收利用。

Lowering viscosity of fracturing fluid by gel breaking and flocculent filtration technology

Fracturing fluid with characteristics of high viscosity and content of organic pollutants was purified and recycled by gel breaking and flocculent filtration technology using Fenton reagent as oxidant,PAC as flocculant.With viscosity as evaluation index,effects of H₂O₂(30%) and FeSO₄(0.5 mol·L^-1) addition in Fenton reagent,pH,time of gel breaking,type and amount of flocculant on viscosity reduction process were investigated.The results showed that to 100 mL fracturing fluid with viscosity of 16 mPa·s,when solution pH was 3,addition of H₂O₂ and FeSO₄ in Fenton reagent were 0.48 mL and 0.3 mL,reaction time was 50 min,gel breaking effect was the best.And the viscosity of solution could be reduced to 1.1 mPa·s after flocculent filtration process by 0.5 g PAC.After comprehensive treatment above,most of the pollutants in the solution were removed and the recycling utilization of the fracturing fluid could be realized.