“…Generally, the timeshift inversion methods minimize a cost function given by the monitor-baseline difference. Rickett et al (2007) point out that if time shifts are large enough to cause cycle skipping, their inversions become even more nonlinear. In addition, inversion methods typically assume that wave propagation is vertical, that changes in reservoir properties are mainly in the velocity and are not influenced by density, and that the seismic traces are nearly zero offset (Williamson et al, 2007).…”