深部煤层气藏低伤害胍胶压裂液评价与应用

    Evaluation and application of low damage guar gum fracturing fluid in deep coalbed methane reservoirs

    • 摘要: 针对深部煤层气储层压裂研发的低伤害胍胶压裂液体系开展评价,并进行现场应用研究。结果表明:低伤害胍胶压裂液破胶时间随着温度增加而减小,在40 ℃条件下,短时间内破胶效果明显;在20 ℃和30 ℃条件下,破胶效果不理想;煤岩心渗透率存在温度敏感性,温度敏感性导致岩心伤害率增加,但变化幅度相对较小;对低伤害胍胶压裂液而言,温度从20 ℃升高至40 ℃,煤岩心温度敏感性对伤害率的增加速度远低于胍胶压裂液随温度的增加对煤岩的伤害率的降低速度,总体表现为低伤害胍胶压裂液对煤岩心伤害率随温度升高显著降低;对于活性水压裂液而言,温度从20 ℃升高至40 ℃,活性水压裂液对煤岩心的伤害率有所增加;在温度为40 ℃以上时,低伤害胍胶压裂液压后2 h返排液黏度达到5 mPa·s,满足现场施工需要;通过同一口井、同一层位水平井采用低伤害胍胶压裂液和活性水压裂液对比,低伤害胍胶压裂液能实现注入液量更少、加砂规模更大、施工砂比更高、施工压力更为平稳的压裂施工工艺。

       

      Abstract: An evaluation of low damage guar gum fracturing fluid system based on deep coalbed methane reservoir stimulation was carried out, its on-site application research was conducted. The results indicate that the gel breaking time decreases with increasing temperature. Low damage guar gum fracturing fluid has a significant breaking expression in a short period of time at temperature above 40 ℃, which is not obvious at 20 ℃ and 30 ℃. The permeability of coal core is sensitive to temperature, which leads to an increase in core damage rate, but the amplitude of change is relatively small. For low damage guar gum fracturing fluid, the increase rate of temperature sensitivity of coal core to damage rate is much lower than the decrease rate of guar gum fracturing fluid damage rate to coal core with the increasing temperature from 20 ℃ to 40 ℃. Overall, the damage rate of guar gum fracturing fluid to coal core significantly decreases with the increase of temperature. For active water, the damage rate of active water to coal core increases when the temperature rises from 20 ℃ to 40 ℃. The backflow fluid viscosity reaches 5 mPa·s of guar gum fracturing in 2 hours at temperatures above 40 ℃, meeting the needs of on-site construction. By comparing the fracturing results of low damage guar gum fracturing and active water in the same well and horizontal well at the same layer, low damage guar gum fracturing fluid can achieve a fracturing process with less injection volume, larger sand volume, higher sand ratio, and smoother pressure.

       

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