Multi-Component Distributed Acoustic Sensing Simulation Using a Novel Stress and Strain-Rate Elastic Wave Equation

Distributed Acoustic Sensing (DAS) is an advanced seismic acquisition technology with many advantages, such as low cost, wide frequency band, dense spatial sampling and continuous recording. The straight optical fiber detects the axial strain changes, while the helical-wound optical fiber captures the strain variations along the tangential direction. To investigate the seismic response of multi-component DAS system, we proposed a novel stress and strain-rate elastic wave equation to simulate the propagation of strain-rate wavefields. Compared to conventional particle-velocity wavefields, the proposed equation can directly generate multi-component normal strain-rate wavefields and produce DAS records. Numerical example illustrates that a helical-wound optical fiber with a winding angle of 35.3º is insensitivity to S-wave, which is similar to traditional pressure component, whereas it can clearly record S-wave at a winding angle of 54.7º.