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针对改性黄原胶低温破胶困难、压裂后出现返胶的问题,研制出了适用于20~50℃储层温度条件下改性黄原胶低温破胶体系,并给出了相应的低温破胶剂体系配方。研究表明,50℃以下时用过硫酸铵做破胶剂存在降粘困难,使用低温破胶引发剂后能够在1~5h内实现有效破胶;黄原胶非交联压裂液对低温破胶引发剂fc-1与fc-2较敏感,且对fc-2尤为敏感,在25~35℃范围内,fc-2含量控制在0.02%~0.04%之间比较适宜;在上述基础上优化了过硫酸铵加量,过硫酸铵浓度控制在0.6%~0.8%之间时,fc-2与过硫酸铵复合破胶体系可实现改性黄原胶低温状况下的有效破胶。该体系在新疆油田低温井的应用取得了较好的效果,对新疆油田改性黄原胶在新疆油田低温储层的压裂改造具有一定的指导意义。
In order to solve the problem that the modified xanthan gum breaks down at low temperature and has the problem of back glue after fracturing, the low temperature gel breaking system which is suitable for the modified xanthan gum under the reservoir temperature of 20 ~ 50 ℃ has been developed. Correspondingly, Low temperature breaker system formula. Studies have shown that 50 ℃ below the use of ammonium persulfate as a breaker there is a viscosity-reducing difficulties, the use of low-temperature broken gel initiator can effectively break gel in 1 ~ 5h; Xanthan gum non-crosslinked fracturing fluid on the low temperature broken The gel initiators fc-1 and fc-2 are sensitive and sensitive to fc-2, and the fc-2 content is controlled at 0.02% ~ 0.04% within the range of 25 ~ 35 ℃. On the basis of the above, The amount of ammonium persulfate, ammonium persulfate concentration control between 0.6% ~ 0.8%, fc-2 and ammonium persulfate composite gel breaking system can be achieved under the conditions of modified xanthan gum under effective gel breaking. The system has achieved good results in the application of low temperature wells in Xinjiang Oilfield and is of guiding significance to the fracturing and reformation of xylene xanthan gum in Xinjiang Oilfield.