Best practise for well log rock physics analysis

We present a tutorial overview of rock physics techniques for quality control and<br>interpretation of sonic and density log data. Major effects that deteriorate the quality of well<br>log data include mud-filtrate invasion, wash-outs, deviated well paths, and erronous sonic<br>velocity picks. The first step in rock physics analysis of well logs is to identify and, if<br>necessary, correct for these effects. The next step is to apply deterministic rock physics<br>models to interpret sonic and density log data. We summarize the most useful rock physics<br>cross plots and models for lithology and pore fluid interpretation of well log data. Finally, we<br>address the importance of establishing a statistical rock physics database, which can be used<br>to assess seismic detectability and as reference data for calibration and classification of<br>seismic attributes.