Experimental study on attenuation of Stoneley wave under different fracture factors

Abstract

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.

Keywords

• Stoneley wave
• amplitude decreasing
• shock tube experiment
• fracture width
• fracture dip angle
• fracture extension