Coupling: Impact and Implications for High-Resolution Time-Lapse Seismic Surveying

Abstract

Attention to specific parameters can minimize inconsistency in source and receiver coupling thereby minimizing changes in spectral characteristics of time-lapse seismic data related to the near surface. This study concludes that the most repeatable Vibroseis source station terrains are firm, unconsolidated sediments that result in 80% shot-to-shot similarity. The least repeatable Vibroseis source station terrains are compacted sediments, resulting in 36% shot-to-shot similarity. Changes in energy containment, transmission, and spectral characteristics of recorded wavefield components occur with repeat shots from downhole projectile sources and appear to be associated with plastic deformation of hole wall sediment. Changes in hole wall sediment conditions with repeat shots has a different effect on surface waves and compressional waves. This observation has potential application to wavefield separation. Acquisition approaches typically used to optimize 2D or 3D high-resolution seismic surveys may reduce repeatability of high-resolution time-lapse data.