The conditioning and analysis of log data for quantitative seismic interpretation are often simply categorized as “rock physics.” Unfortunately, rock physics workflows often overlook or oversimplify the proper editing and interpretation of log data, and the result can be unrealistic expectations and interpretations of seismic amplitude responses. The more encompassing phrase “seismic petrophysics” better describes the necessary linkage between petrophysics and rock physics. Seismic petrophysics not only includes rock physics, but also the proper conditioning and interpretation of log data that should occur prior to the application of rock physics and seismic models. This is especially true in conditioning log data for shear-wave velocity estimation, fluid substitution calculations, and AVO modeling.

This talk will focus on the important role of “seismic petrophysics” in the quest to extract additional information from subtle seismic responses. Topics covered will include various aspects of log editing, petrophysical interpretation (including integration of other data sources- core, fluids, pressures, etc.), and some common pitfalls associated with the “workhorses” of rock physics (invasion corrections, shear velocity estimation, and elements of fluid substitution). It is important to recognize that log data should not simply be recomputed to fit prior expectations as defined by a rock physics model. Instead, rock physics models should be used as templates, which allow the interpreter to understand the underlying physics of observed log responses and how they are governed by local petrophysical properties. Case studies will be used to reinforce critical concepts.