Modelling seismic time‐lapse changes in the overburden and in the reservoir as a result of reservoir depletion

Variations in pressure (and saturation) at reservoir level over time influence not only the geomechanics of the reservoir, but also of the surrounding medium. Differences in the geomechanics bias the time-lapse seismic analysis. Using geomechanical and reservoir modelling it is possible to solve the forward problem and monitor the seismic attributes (travel time and amplitude) as a function of changes in the geomechanical model. This solution is then used for solving the inverse problem (i.e., finding the changes in the rock physics parameters over time from the time-lapse changes in the seismic response). Amplitude and travel time 4D changes, in the overburden and in the reservoir, should be monitored to achieve one accurate quantification of the time-lapse changes at the reservoir level.