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Because natural cracks are not smooth cracks, in the process of identifying cracks by acoustic and electrical imaging, if cracks are regarded as smooth cracks, errors will be generated. Stoneley wave reflection coefficient has high sensitivity to crack width, and stoneley wave is often used to identify cracks. Physical experiment and numerical simulation were used to study the influence of rough fracture on acoustic response. In the aspect of experiment, the crack roughness experiment of model well was carried out, and the relationship between crack width and attenuation coefficient of rough crack was obtained. Numerical simulation of horizontal crack borehole model was carried out to study the influence of sinusoidal rough crack on stoneley wave. The roughness of crack surface was described by tortuosity. The experimental results show that the attenuation coefficient of stoneley wave will increase with the increase of notch on the crack surface. The simulation results show that the smaller the width of rough crack, the larger the gap between the attenuation coefficient of smooth crack and the same width. The relationship between stoneley wave attenuation coefficient and crack width and tortuosity is established by fitting. [ABSTRACT FROM AUTHOR]

To quantitatively determine the effect of different factors such as fracture width, dip angle, extension and filling material on Stoneley wave amplitude decreasing, the shock tube experiment method was changed from fixing the sample and vertically moving the sensor in the borehole to fixing the sensors along the shock tube wall and vertically moving the sample without drilling the borehole in it. The measurement accuracy and the signal-to-noise ratio of the first Stoneley wave were improved by the time corrections and amplitude corrections of Stoneley wave signals. At the same time, 21 sets of core models with different fracture parameters were processed for this measurement method by using full-diameter carbonate core, and relative amplitudes were defined to characterize Stoneley wave amplitude decreasing. The experimental results show that the relative amplitude of Stoneley wave exponentially decreases with increasing fracture width. The relative amplitude of Stoneley wave linearly decreases with increasing fracture dip angle. The relative amplitude of Stoneley wave exponentially decreases with increasing fracture extension. The relative amplitude of Stoneley wave decreases with increasing the permeability of filling material in the fracture. Under the above four conditions, the fracture width has the greatest effect on the decreasing of Stoneley wave amplitude, followed by the fracture extension and the permeability of filling material, and finally the fracture dip angle.