Quantitative estimation of pressure and saturation changes using 4D seismic -A case study in the marlim field, Brazil

The technique of Floricich (2006) is used to estimate pressure and saturation changes from 4D seismic data without the need for rock or fluid physics. This methodology involves a multiple attribute approach in which a sequence of calibration, training and selection produces an optimal combination of the attributes for the final inversion. A Bayesian inversion from the 4D data is then performed taking into account the uncertainties related to the production data and seismic attributes. The methodology is applied to an Oligocene field, offshore Brazil, with encouraging results. Estimates of the amount of injected water in the system between the two vintages are obtained using the saturation maps and the simulation model, and the comparison is used to assess the material balance in the area.