清洁压裂液在煤层气井压裂中的应用

陕西省韩城市地区煤层气井的主要目的煤层底界与奥灰系含水层的距离不足10 m,为了提高单井增产改造的效果,并最大程度地降低对煤层的伤害,选用清洁压裂液进行该地区煤层压裂。针对该地区煤层特点,室内试验对清洁压裂液配方及破胶剂进行了优选,对优选配方的流变性、携砂能力、滤失控制能力、对煤层的伤害性进行了评价,介绍了其现场应用情况。使用清洁压裂液在该地区压裂3口井8层,施工成功率为100%,其摩阻仅为活性水摩阻的38%,压裂井的日产气量是活性水压裂井的一倍以上。室内试验及应用结果表明,清洁压裂液对煤层中的粘土有良好的防膨效果,能够降低粘土膨胀对煤层的伤害;抗剪切能力强,在较低粘度下就具有良好的携砂能力,压裂时排量的选择空间较大,能够形成长的支撑裂缝;摩阻较低,可以降低施工时的水马力;配制简单,用液量少,便于缺水地区使用。

Clean Fracturing Fluid for The Coal-Bed Gas Well

In Shaan'xi Hancheng area,the distance between the bottom of key coal bed and the pay zone of Ordovician was less than 10 m.The clean fracturing fluid was employed to improve individual well production and minimize the coal bed damage.The formulation of fluid was determined and the breaker was optimized by laboratory experiments in the light of the coal bed characteristics.Then evaluation tests were conducted to examine the fracturing fluid's rheological property,prop carrying capacity,loss control capacity and damage to the coal bed.The field application was presented.The clean fluid was employed in 8 beds' frac jobs occurred in three wells and achieved full success.The friction drag of the clean fluid was only 38% of that of active water.The CFGPD was greater than one times of that of active water.Lab tests and field application results indicated that the clean frac fluid had favorable swelling inhibition and thus reduced coal bed damage induced by that.It had strong shear strengthen and more pump discharges available as a result of excellent prop carrying capacity at lower viscocity and thus can generate long fracture.The lower hydraulic horsepower was available due to clean fluid's lower drag.The preparation of the fluid was simply and it could be a attractive alternative thanks to little fluid volume required in water deficient area.