Seismic time-lapse interferometry across scales

Abstract The ambient seismic wavefield or noise is the ubiquitous low-amplitude background ground motion that is recorded by all seismic sensors. The recorded signals are characterized by a seemingly random train of continuous waveforms. However, the cross-correlation of seismic ambient wavefield records from different receiver locations yields estimates of the interstation Green's function that is the impulse response of a virtual seismic source. This and related concepts are commonly referred to as seismic interferometry. The complete Green's function retrieved from the ambient field or ambient noise contains direct body waves and surface waves, reflections, multiples, and multiply scattered coda-waves. For time-lapse applications targeting the detection and imaging of changes in the propagation medium, coda waves are the primary target. This coda-wave interferometry is now an established and powerful approach that relies on the increased sensitivity of coda waves to small variations of physical properties compared to the resolution of direct waves. In this chapter, we introduce the theoretical and methodological framework of time-lapse interferometry. We discuss applications including subsurface imaging using the ambient field, reservoir imaging and monitoring using controlled-source data, and laboratory scale ultrasound approaches.