Rock Physics Estimation of Stress Sensitivity and Associated Time Shifts in the Visund Field, North Sea

Rock physics models for stress dependency in reservoir rocks are essential for quantification and interpretation of 4-D seismic signatures during reservoir depletion and injection. In this study, we apply a rock physics modelling approach to quantify seismic time shifts and time shift derivatives associated with stress changes. The time shifts will be a function of the rock stiffness, and it is therefore important to determine the local changes in rock properties before we can predict stress and fluid sensitivity from time shift attributes. We apply this approach to 4 wells in the Visund Field area and compare the results with observed time shift attributes. Using this approach, we estimate the expected pressure change at the different well locations where we have good control of the dry rock properties. With a good understanding of local geology, the approach can also be used to interpret pressure and fluid changes from time shifts in interwell areas.