Moment tensor analysis of acoustic emissions induced by laboratory-based hydraulic fracturing in granite
Moment tensor analysis of acoustic emissions induced by laboratory-based hydraulic fracturing in granite
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DOI：
10.1093/gji/ggy493
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发表时间：
2018-11
影响因子：
2.8
通讯作者：
Kazune Yamamoto;M. Naoi;Youqing Chen;Kengo Nishihara;S. Yano;H. Kawakata;Takashi Akai;I. Kurosawa;T. Ishida
中科院分区：
文献类型：
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作者：
Kazune Yamamoto;M. Naoi;Youqing Chen;Kengo Nishihara;S. Yano;H. Kawakata;Takashi Akai;I. Kurosawa;T. Ishida
水力致AE的矩张量：水力压裂是开发增强型地热系统和非常规资源的重要技术。虽然水力压裂引起的裂缝模式影响资源的采收率，但目前对这种关系的理解是不够的。在这项研究中，我们考虑了在实验室中的单轴加载条件下的水力压裂过程中引起的声发射（AE），并通过仔细校正的耦合条件和AE传感器的方向性应用的矩张量分析。对两种类型的黑上岛花岗岩样品进行了实验：裂缝面垂直于预期裂缝扩展方向（即沿着加载轴）（H型）或平行于预期裂缝扩展方向（V型）的样品。在实验中，两种样品类型都经历了大量的剪切、拉伸和压缩事件。H型样品的主导断裂模式被发现是拉伸事件，其中断裂面平行于加载轴，而V型样品，剪切事件占主导地位。这种差异表明，水力压裂引起的主导断裂模式高度依赖于断裂扩展方向与预先存在的弱面取向之间的关系。
Moment Tensors of hydraulically induced AEs: Hydraulic fracturing is an important technique in the development of enhanced geothermal systems and unconventional resources. Although the fracture modes induced by hydraulic fracturing influence the recovery efficiency of the resources, the current understanding of this relationship is insufficient. In this study, we considered the acoustic emissions (AEs) induced during hydraulic fracturing under uniaxial loading conditions in the laboratory, and applied a moment tensor analysis by carefully correcting the coupling condition and directivity of AE transducers. Experiments were conducted for two types of Kurokami–jima granite samples: those with a rift plane perpendicular (Type H) or parallel (Type V) to the expected direction of fracture propagation (i.e. along the loading axis). In the experiments, both sample types experienced a significant number of shear, tensile and compressive events. The dominant fracture mode for Type H samples is found to be tensile events in which the fracture plane is parallel to the loading axis, whereas for Type V samples, shear events are dominant. This difference suggests that the dominant fracture modes induced by hydraulic fracturing are highly dependent on the relationship between the direction of fracture propagation and orientation of pre-existing weak planes.