Rock Physics Diagnostic in a Sand/Shale Sequence

Geophysics and inversion of seismic data has improved considerably over the last decade. So much so that elastic inversion is fast becoming a commodity data product that oil companies understand and use for risk reduction. Many examples have been shown where the elastic impedance is used to estimate porosity, for example using a statistical regression on well data. In this paper we will review the use of Rock Physics Diagnostics applied to log data that illustrates a relational model between porosity, clay and saturation. We use these relations to estimate porosity from elastic impedance attributes. Using statistical fits may work locally around the property values experienced by a well for example but away from the well you need to employ some systematic approach to improve the confidence and reduce the risk associated with such estimations. Such a systematic approach is Rock Physics Diagnostics and we believe that this methodology is essential for extracting rock properties from seismic data