oa Feasibility of P-S Converted Wave Imaging for the DAS Active Seismic with Surface Deployed Optical Fibers

Distributed Acoustic Sensing (DAS) is an important technology for a long-term monitoring for geological carbon storage as optical fiber cables are durable for years. Theoretically, DAS measurement using optical fibers deployed on surface (S-DAS) record P-P reflected and P-S converted wave simultaneously in an active seismic survey. This study explores the possibility of the P-S converted wave imaging with S-DAS 2D land seismic data from a field trial conducted in Japan.

We performed preliminary P-P reflection processing and P-S converted reflection processing on the same data set. Reflection events that is not clear in the P-P reflection image are observed clearly in the P-S converted reflection image in the shallow area. This may be attributed to the difference in impedance contrasts and sensitivity of DAS for a wave incident angle to cable. Imaging of deep area might be challenging in terms of the degree of S wave attenuation.

We confirm that S-DAS measurement can give subsurface image both by P-P reflection and P-S converted wave, and that P-S converted wave gives additional information to leakage monitoring for shallow zone in the geological carbon storage.