塔里木油田酸压返排液重复利用研究

Research on reutilization of acidizing flowback fluid in Tarim Oilfield

为确定组成复杂、浮油和高价金属离子含量高、酸性强的塔里木油田酸压返排液处理后能否顺利地配制压裂液,通过对返排液水质分析,提出了一套"过滤-化学沉淀-絮凝沉降-压裂液配制"的处理工艺。大量的浮油影响压裂液的溶胀及交联,滤布过滤可去除浮油与块状杂质组成的黏稠物;高价金属离子阻碍稠化剂分子的伸展,影响压裂液的携砂性能,碳酸钠可直接沉淀金属离子并中和残酸;简单处理之后需絮凝剂进一步絮凝处理,除去返排液中的小颗粒杂质。将处理后的水调节至中性或弱酸性直接配制成压裂液使用,可杜绝环境污染,缓解油田水资源匮乏问题。沉淀剂质量浓度为145g/L、絮凝剂质量浓度为1 000mg/L时,返排液中悬浮颗粒杂质的去除率达98%,水质平均粒径2.36μm。利用处理后的酸压返排液配制的压裂液挑挂性能良好,其流变性能和黏弹性能与清水直接配制的压裂液相差不大,均满足SY/T 6376-2008《压裂液通用技术条件》常规压裂液性能标准,适用于塔里木油田超深井高温高剪切要求。研究表明,酸压返排液重复利用配制压裂液的工艺是可行的。

In order to determine the possibility of prepare fracturing fluid using treated acidizing flowback fluid in Tarim Oilfield, which includes complicated composition, highoil,metaf ions and acids, one set of processing containing＂ filter-chemical precipitation-flocculation sedimentation- preparation fracturing fluid＂ was put forward through the analyzing of flowback paper. Filtration was done to remove oll and lumps by iilter cloth because a large number of oll affects the swelling and crosslinking of fracturing fluid. Metal ions were precipitated and residue acids wereneutralized directly by sodium carbonate in order toeliminate thebad influences ofhigh metal ionsaffecting the guar molecules stretch and the carrying sand performance of fracturing fluid. It needs further flocculation treatment by flocculant to despite the small particles impurities from acidizing flowback fluid after simple processing. Finally, the flowback fluidwas used to prepare fracturing fluid under neutral or weak acid conditions to prevent environmental pollution and alwater shortages in Tarim Basin. The experiments showed that the removal rate of suspended solids reaching 98% and the average diameter distribution was 2. 36jum when the precipitant was 145 mg/L and flocculant was 1 000 mg/L. The suspension performance of fracturing fl uid prepared by treated acidizing flowback fluid was great and its rheological property and viscoelasticity were similar to thefracturing fluid prepared by tap-water, and also met the standard SY/T 6376 - 2008 General Technicrl Condition of Fracturing F lu id . It could satisfy the require of high teshear in ultra deep well in Tarim Basin. In short, the research showed that the recycle process ofacidizing flowback fluid could be achieved.