Impact of Overburden Anisotropy on Stress Changes and 4D Seismic Response

Geomechanical anisotropy of shale overburden gives largely different estimates of stress and pore pressure changes which again impact on overburden 4D seismic response. The combined use of lab (static elastic moduli, Skempton parameters and velocities vs stress) and geomechanical modelling enables prediction of 4D attributes (e.g., time-shifts). Further work along these lines, incorporating anisotropic wave propagation and AVO response (Bakk et al., 2020), point in the direction of possible derivation of stress and poressure changes from 4D. Non-resolved issues are the impact of frequency dependence in stress sensitivity.Also, impacts of temperature changes should be considered.