煤岩脉动水力压裂过程中声发射特征的试验研究

发布时间：2018-06-01 19:47

本文选题：煤岩 + 脉动水力压裂　；参考：《中南大学学报(自然科学版)》2017年07期

【摘要】：利用真三轴加载脉动水力压裂试验系统和PAC声发射仪,开展不同注液频率和不同压裂液黏度条件下煤岩脉动水力压裂过程的声发射(AE)试验研究,揭示煤岩脉动水力压裂过程中声发射参数、损伤演化规律及震级-频度关系参数b的动态特征。试验结果表明:煤岩在脉动水力压裂过程中,声发射行为演化过程可划分为平静期、提速期、加速期和稳定期4个阶段,其中提速期和加速期累积能量均值较平静期分别提高40.9和52.7倍;煤岩损伤演化过程可分为初始阶段、损伤发展阶段及损伤加速发展阶段,煤岩的声发射特征能较好地描述其损伤演化特性;脉动频率较低时煤样的AE活动水平和能量释放越强,裂隙发育程度越高;当压裂液黏度较高时,煤样的AE活动水平和能量释放越弱,裂隙发育程度较低;在煤岩脉动压裂整个过程中,当脉动频率或压裂液黏度较低时,煤岩AE振幅分布变化幅度较大,且其b更大,大尺度AE事件比例更低。
[Abstract]:By using the true triaxial loading pulsating hydraulic fracturing test system and PAC acoustic emission instrument, the acoustic emission (AE) test of fluctuating hydraulic fracturing process of coal and rock under different injection frequency and different fracturing fluid viscosity was carried out. The dynamic characteristics of acoustic emission parameters, damage evolution law and magnitude frequency relation parameter b during pulsating hydraulic fracturing of coal and rock are revealed. The experimental results show that the evolution process of acoustic emission behavior of coal and rock during pulsating hydraulic fracturing can be divided into four stages: calm period, acceleration period and stable period. The accumulative energy in the accelerating period and the accelerating period are 40.9 and 52.7 times higher than those in the quiet period, respectively. The process of damage evolution of coal and rock can be divided into three stages: initial stage, damage development stage and damage accelerated development stage. The acoustic emission characteristics of coal and rock can better describe the damage evolution characteristics; the stronger AE activity level and energy release of coal sample are, the higher the fracture development degree is when the viscosity of fracturing fluid is high, the higher the AE activity level and energy release of coal sample are, the higher the fracture development degree is when the viscosity of fracturing fluid is high. The weaker AE activity level and energy release of coal samples, the lower the degree of fracture development, and the larger the amplitude distribution of AE amplitude in coal and rock is, and the larger its b is, when the pulse frequency or viscosity of fracturing fluid is lower, the amplitude distribution of AE in coal and rock is larger than that in coal and rock during the whole process of pulsating fracturing. The proportion of large scale AE events is even lower.
【作者单位】：中南大学有色金属成矿预测与地质环境监测教育部重点实验室;中南大学地球科学与信息物理学院;湖南科技大学页岩气资源利用湖南省重点实验室;
【基金】：国家自然科学基金资助项目(41302124) 湖南科技大学页岩气资源利用湖南省重点实验室开放基金资助项目(E21425) 中南大学中央高校基本科研业务费专项资金资助项目(2015zzts066)~~
【分类号】：TD712.6

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