Study of distributed acoustic sensing data waveform inversion based on strain rate

Distributed Acoustic Sensing (DAS) is a new seismic observation system that has developed rapidly in recent years. Compared with traditional geophones, DAS has the advantages of a wide application range, high resolution, etc. Traditional geophones record particle velocity, while DAS receives axial strain rate signals along with the fiber. So, the conventional full waveform inversion (FWI) based on the velocity-stress wave equation cannot be directly used for the DAS strain rate data inversion. The previous FWI DAS method converts the strain rate into particle velocity, amplifying low wave number noise and affecting the inversion accuracy under a low signal-to-noise ratio (SNR). This paper proposed the DAS-FWI method directly based on strain rate data. Firstly, we derive the elastic wave full-waveform inversion theory based on strain rate parameters. Then, the typical synthetic model and DAS field data tests demonstrate the feasibility and effectiveness of the proposed strain rate DAS FWI method in velocity tomogram.