How Compaction Causes Misaligned Multiples and False Time Shifts in Time-lapse Seismic

This paper argues that in time lapse-seismic with significant overburden time shifts, the time shifts experienced by multiples will exceed those experienced by the surrounding primaries. These misaligned multiples will lead to an overestimate of measured time shifts, especially in areas where multiple energy is strong compared to primary energy. This mechanism explains high time shifts observed in the underburden that are hard to understand otherwise. The phenomenon is formulated in simple arithmetic terms, and is supported by both model computations and real observations on the Tyra field.