A new full-wave simulation of wave propagation at the scale of laboratory samples is presented. The objective is to provide a tool to better understand the complex interplay between different waves propagating in rock samples during fluid substitution processes. The model is based on a 3D finite difference scheme used to solve the elastodynamic equation in cylinders of porous rock with an isotropic viscoelastic rheology. The general idea is to simulate real lab experiments for which the outcome of the modeling can be compared to real data. Two examples of application are presented. Case study 1 corresponds to the simulation of an oil injection experiment in a dry chalk sample: although a first-order agreement was found, the model failed in reproducing the complexity of the recorded signals due to the lack of knowledge of the oil saturation profile through time. Case study 2 is a water injection test in another dry chalk sample: in this experiment, the evolution in space and time of the water saturation profile could be estimated, and the numerical modeling results were successful in matching the experimental observations with few discrepancies. The new modeling tool can be used to help the interpretation of complex recorded signals resulting from wave interference and to improve the rock physics model in changing environments such as in 4D seismic, where fluid substitution processes are at play.

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