摘要
针对页岩气藏清水压裂时由于施工排量大,导致液体所受剪切速率较高的现状,利用大型摩阻测定仪,对4种阴离子型减阻剂进行室内评价。结果表明,4种减阻剂的降阻效果均随着剪切速率的增大而趋于变好,其中XT-65B的降阻效果最好。通过分析剪切速率、剪切时间和剪切路径等对减阻剂降阻效果的影响可知:随着剪切速率的增加,减阻剂降阻率呈下降趋势;在低速剪切(500 s-1)条件下,减阻剂降阻率对剪切时间不敏感,而在高速剪切(5 000 s-1)时,减阻剂降阻率随剪切时间的增加而急剧下降;不同剪切路径对减阻剂降阻效果影响显著,较高的剪切速率会对减阻剂分子结构造成不可恢复的伤害。由电子显微镜对XT-65B减阻剂剪切前后的分子结构微观观测结果可见:当剪切速率较低(500 s-1)时,分子结构被轻微破坏;当剪切速率较高(5 000 s-1)时,分子结构破坏较为严重。
Based on the characteristics of fluids suffering high shear stress caused by large pumping rate in slick water fracturing ofshale gas reservoir,evaluation of four kinds of anionic drag reducer is carried out in laboratory at high shear rates utilizing large frictiontester.The results show that,the drag reducer XT-65B has a better drag reduction efficiency,which can be up to 56%.Meanwhile,thefactors affect the drag reduction efficiency,such as shear rates,shearing time and shearing path,are analyzed as well.With the increaseof shear rate,resistance reduction rate of drag reducers is on the decline.At low shear rete conditions(500 s-1),the resistance reductionrate of drag reducers is not sensitive to the shear time; at the high shear rate conditions(5 000 s-1),the resistance reduction rate of dragreducers cut sharply with the increment of shearing time.Different shear paths affect the performance of drag reducers significantly,high shear rate can exert an unrecoverable damage on the molecular structure of drag reducer.The micro-structure of drag reducer mol-ecule of XT-65B before and after shearing is also observed with the help of SEM,confirming that the drag reducer molecule is little af-fected at low shear rates(500 s-1)and degrades greatly at high shear rates(5 000 s-1),which has a good agreement with the experimental results.
出处
《油气地质与采收率》
CAS
CSCD
北大核心
2014年第2期102-105,118,共4页
Petroleum Geology and Recovery Efficiency
基金
国家科技重大专项"3000型成套压裂装备应用技术研究及应用示范"(2011ZX05048-006-002)
关键词
页岩气藏
清水压裂
减阻剂
性能评价
降阻率
高速剪切
shale reservoir
slick water fracturing
drag reducer
performance evaluation
drag reduction efficiency
high shear rates
