Improvements in Pore Fluid Substitution

B-7 IMPROVEMENTS IN PORE FLUID SUBSTITUTION Abstract 1 The conventional way of performing pore fluid substitution is to use Gassmann's equation which requires knowledge of the dry rock properties as well as matrix parameters. We have introduced an alternative approach based on lithological models where all the necessary parameters are implicit in the model. This is a very efficient procedure which automatically takes care of the effect of lithological variations. To overcome some of the weaknesses in connection with the application of Gassmann's equation we have combined the equation with a dry rock model. This combination can be done in