PROCESS FOR CHARACTERISING THE EVOLUTION OF AN OIL OR GAS RESERVIOR OVER TIME

Disclosed is a process for characterising the evolution of a reservoir by co-analyzing the changes in the propagation times and seismic amplitudes of seismic reflections. The method comprises the steps of: providing a base survey of the reservoir with a set of seismic traces at a first time; providing a monitor survey of the reservoir, taken at a second time, with a set of seismic traces associated to the same positions as in the base survey; and characterising the evolution of the reservoir by inversion to obtain an estimate of the changes having occurred during the time interval between base and monitor surveys. The inversion is regularized by the imposition of a sparsity constraint, such as Cauchy sparsity, which favours inversion solutions for which most of the solution values are equal to zero, while large values of said inversion solutions are preserved.