Estimation of seismic velocity and layer thickness of eagle ford formation using microseismic guided waves in downhole distributed acoustic sensing records

Application of the distributed acoustic sensing (DAS) technique has grown rapidly in geophysics in recent years and enables seismic measurements in restrictive downhole conditions. In downhole hydraulic fracturing operations, the DAS fiber instrumented along the horizontal well can detect effectively the microseismic-induced guided waves that travel within the shale formation of the unconventional reservoir. These guided waves show significant dispersion features along the DAS fiber that can be utilized to calibrate the velocity structure of the reservoir. Modern surface wave methodology can be adapted for guided wave inversion and crucial model parameters such as shale formation thickness and S-wave velocity can then be retrieved effectively. In this study, we demonstrate the efficacy of guided wave analysis for reservoir structure estimation on both synthetic and field microseismic datasets of the Eagle Ford formation. The combination of local microseismic events and the downhole DAS array provides a novel and cost-effective seismic survey strategy using guided waves to acquire valuable information about the structure of the unconventional reservoir.