Fracture Detection using S-wave Reflections and Stoneley Wave from Full-Waveform Sonic Data

Summary Sonic logging tools are typically equipped with multiple monopole and dipole transmitters as well as several receivers to acquire full waveform data. The Full-waveform sonic data include several modes including P-wave, S-wave and Stoneley waves. The primary objective was to utilize the full waveform data to investigate if the seismic lineaments observed in the area were caused by fractures. Two methods were used to characterize fractures from full-wave sonic. Firstly, the Normalized Differential Energy (NDE) method was applied to the Stoneley waves with the aim to detect near-well bore fractures (less than 6 feet away). Secondly, Reverse Time Migration (RTM) images of dipole’s S-waves were generated with the aim to image fractures that are up to 200 ft way from the wellbore. The results obtained by both methods were further validated with respect to borehole image logs (BHI), showing a very good agreement between the different methods. The results suggest that the seismic lineaments are probably caused by fractures.