When two phases of fluid are present within a porous rock, there is an a priori possibility that the distribution (on the intergranular scale) of the fluid phases may affect the elastic and attenuative properties of the rock. If this were true, it could have important implications for the interpretation of seismie veloeities, especially since the microscopic distribution (as weIl as the macroscopic distribution) may vary during production of a hydrocarbon reservoir, and since the production process may be monitored remotely by seismic means.