Quantification of residual oil saturation using 4D seismic data

A method has been developed to quantify residual oil saturation using 4D seismic differences interpreted at fluid contacts. The development is different from previous approaches in that it uses only the seismic amplitudes at the original and produced oil-water contacts instead of the top reservoir event. It requires that these contacts be visible in the 4D seismic data, although not necessarily in the 3D seismic. It is shown that the method can provide a quick semi-quantitative analysis of published field studies from visual inspection. The approach is further demonstrated by application to a field dataset from a North Sea oil reservoir. The results of this application show good agreement with the simulation model, but also some variations that suggest such residual oil estimates could be used in future history matching to update the simulation model.