Abstract Homogeneous, rock-like materials are fractured in this experimental study using a viscous liquid (glycerin) and nitrogen gas to provide a fundamental insight on the effect of using compressible gases compared to hydraulic fracturing fluids. The fracturing process in the experiments are captured using sequences of high resolution images as well as a novel application of Digital Image Correlation for crack detection. We show that fractures propagate through test specimens in a gradual manner when induced by glycerin at various injection rates. In contrast, nitrogen injection induces instantaneous fractures, which we attribute to its compressible nature and ultralow viscosity. The specimen breakdown pressure is also shown to be markedly lower for nitrogen fractures compared to glycerin fractures. The significantly higher pore pressure distribution and induced tensile stresses associated with nitrogen injection are demonstrated through numerical simulations of the laboratory experiments. Moreover, an experimental evidence of fluid lag when fractures are induced with viscous fluids is provided.

中文翻译：

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使用可压缩和不可压缩压裂液实现裂缝起裂和扩展的实验室可视化

摘要 在这项实验研究中，使用粘性液体（甘油）和氮气压裂均匀的岩石状材料，以提供对使用可压缩气体与水力压裂液相比的影响的基本见解。实验中的破裂过程是使用高分辨率图像序列以及数字图像相关性用于裂缝检测的新应用来捕获的。我们表明，当在不同注入速率下由甘油诱导时，裂缝以逐渐的方式通过试样传播。相比之下，注入氮气会引起瞬时裂缝，我们将其归因于其可压缩性和超低粘度。与甘油断裂相比，氮气断裂的试样破裂压力也显着降低。通过实验室实验的数值模拟证明了与注氮相关的显着更高的孔隙压力分布和诱导拉伸应力。此外，还提供了用粘性流体诱导裂缝时流体滞后的实验证据。