DAS observation of guided waves in a shale reservoir generated by perforation shots

We show distributed acoustic sensing records of guided waves excited by perforation shorts in a low-velocity shale layer. Thanks to the high spatial and temporal resolution of distributed acoustic sensing acquisition, high frequencies of up to 700 Hz can be observed. We analyze and validate the existence of such waves with synthetic modeling and by comparing their presence in horizonal and vertical parts of the well. These guided waves are trapped within the low velocity organic shale reservoir. Using a simple synthetic experiment, we show that these waves are sensitive to small velocity changes induced by stimulation. Since distributed acoustic sensing allows high spatial and temporal sampling, these guided waves can be measured with high resolution, allowing them to be used for imaging and analysis.