Overburden 4D time shifts induced by reservoir compaction at Snorre field

Abstract Interpreting and understanding overburden seismic changes are important to avoid health, safety, and environmental (HSE) accidents and well-drilling problems. Furthermore, overburden time shifts might indicate areas with reservoir compaction and depletion. In the Snorre sandstone field, 4D seismic time shifts of as much as 3 ms are observed in the overburden. The cumulative overburden time shifts captured at top reservoir correlate well with pressure-depletion areas in the reservoir, indicating that the time shifts might be related to changes in stress and strain because of reservoir compaction. For further investigation, a 2D geomechanical model is built in the area with the most prominent overburden time shifts. Based on the stiffness of the reservoir and surrounding rocks and simulated reservoir pore-pressure changes, the geomechanical model predicts a maximum downward displacement at the top reservoir of 0.4 m and maximum seabed subsidence of 0.25 m. By defining an appropriate strain-sensitiv...