电脉冲水压致裂煤岩超声波检测评价方法

Ultrasonic testing and evaluation method for hydraulic fracturing coal by voltage pulse

为了定量评价电脉冲水力压裂煤岩体致裂效果,确定该技术适用于工程实践中的电压及水压的加载量,设计了电脉冲水压致裂超声波检测试验方案,并通过数值计算从损伤变量、裂缝扩展宽度两个评价指标定量表征该技术在不同加载条件下对煤岩体的致裂效果,及相较于单纯静水压力压裂的优越性。实验结果表明:①由于加载液电压力存在的波动性,其损伤程度在钻孔周围破坏最严重,随着波动压力的减弱,煤岩体损伤程度逐渐降低;②损伤变量及裂缝宽度与加载电压之间呈正相关关系,均随着电压的增加而增加;③通过损伤变量、裂缝宽度这两个指标定量分析了电脉冲水压致裂煤体效果,可为煤层气开采提供参考。

In order to quantitatively evaluate the fracturing effect of hydraulic fracturing by voltage pulse on coal rocks,and determine that whether the technology is suitable for the voltage and water pressure loading in engineering practice or not,the voltage pulse hydraulic fracturing ultrasonic testing test is designed,the fracturing effect of this technique on coal rocks under different loading conditions is quantitatively characterized by the numerical calculation from damage variables and crack propagation width,and its advantages compared to the operation of hydrostatic fracturing merely is evaluated.The conclusions are as follows:①Due to the fluctuation of load fluid electrical pressure,the damage degree around the borehole is the most serious,reducing with the decreases of the fluctuating pressure.②The damage variables and crack width are positively correlated with the loading voltage,which increase with the increase of voltage.③The fracturing effect of hydraulic fracturing by voltage pulse on coal is quantitatively analyzed from damage variable and crack width,which can provide reference for coalbed methane.