An effective inclusion-based rock physics model for a sand–shale sequence

A simple inclusion-based rock physics method is investigated for modelling the elastic logs recorded in a sand–shale sequence. The model uses a single aspect ratio at each depth applied to the total porosity. The aspect ratio varies with depth whilst the elastic properties of the component minerals are held constant. The variation in the effective aspect ratio with depth is predictable from petrophysical properties. Once the relationship has been established, it can be used to identify and correct data quality issues and improve the petrophysical interpretation, resulting in a consistent and corrected set of logs for seismic reservoir characterization workflows. The model relies on the ability to predict both shear and compressional velocities using a single aspect ratio at each depth, and on this aspect ratio being predictable from data other than the elastic logs themselves. It is not anticipated that these criteria will be fulfilled for all rocks. However, it is expected that even when the method fails the results will still lend insight into the physics of the rocks.