胍胶压裂返排液残渣净化处理技术

Purification of discharged residual guar fracturing fluid

常规胍胶压裂返排液残渣净化处理过程中,只考虑残渣的含量是否达到排放标准,并没有对净化处理后残渣粒径是否达到排放标准进行研究。以残渣粒径不大于1μm作为评价标准,采用＂絮凝处理＋活性炭处理＂的方法进行压裂返排液净化处理实验。实验结果表明,明矾、聚合氯化铝（PAC）、聚合硫酸氯化铁铝（PAFCS）等3种常用絮凝剂处理后的残渣粒径处于1-2μm,其中PAFCS絮凝处理效果最好,其最优实验条件为：加量2.5 g/L,粒径0.25-0.3 mm,搅拌时间20 min,静置时间30min;明矾、PAC、PAFCS絮凝处理后的液体中分别加入4.5 g/L、4 g/L、3.5 g/L活性炭,净化处理后残渣粒径小于1μm,残渣粒径及残渣含量均达到国家排放标准。

In the process of conventional purification of discharged residual guar fracturing fluid, only residue content is required to meet applicable discharging standard, but no consideration has been given to granular diameters of such residues after purification. Taking the residual grain diameter of no more than 1 μm as the benchmark for assessment, ＂flocculation＋active carbon＂ treatment was used for purification of discharged fracturing fluid. Test results show three conventional flocculants： alum, polymeric aluminum chloride（PAC） and polymeric aluminum-ferric chloride sulfate（PAFCS） can be used to produce residues with grain diameters of 1-2 μm. Among them, PAFCS displays the best flocculation performance at optimal test conditions as follows, Volume of agent is 2.5 g/L, grain diameter is 0.25-0.3 mm, stirring time is 20 min, settling time is 30 min, active carbon with concentration of 4.5 g/L, 4 g/L and 3.5 g/L, respectively, were added to the fluid produced upon completion of flocculation involving alum, PAC and PAFCS. After completion of purification, all residues have grain diameters less than 1 μm, and both grain diameter and content of residues conform to applicable discharging standard.