oa Seismic frequency variations of a reservoir: Lessons from a spring

In studying wave propagation and attenuation in the Earth, it is often convenient to use simplified models. One of these models is a mass, spring and dashpot to model oscillation and attenuation. By analyzing the motion of a spring using different forced oscillations, we studied the effect of the system’s characteristics on the transmitted frequency. In particular, we observed that if the forced oscillations are above the system response, the predominant output will be at the system characteristic. For lithologic layers, the system characteristics depend, in part, upon the Poisson’s ratio, matrix and the fluid velocities. With reservoirs having different fluid velocities and often different Poisson’s ratios from the surrounding rock; this implies that hydrocarbon reservoirs could have a measurable spectral character based upon their unique system or rock properties and that these characteristics could be estimated with seismic data.