Seismic velocities from experimental compaction: New porosity and velocity-depth relations for sands with different textural and mineralogical composition

Velocity depth trends are the key to seismic modeling and also important in seismic processing (velocity analysis and depth conversion, NMO and DMO corrections) and inversion of seismic data. A Comparison of a standard velocity-depth trend with an actual velocity-depth trend may lead to a variety of new information. For example, the deviation of an actual velocity-depth trend compared to a theoretical or an empirical trend may indicate uplift/erosion, cementation, over-pressure, and/or presence of hydrocarbons. The few methods in use today either employ empirical sand baselines or rock physics models. We present new empirical equations for porosity and velocity prediction as functions of sand grain-size, shape, sorting and mineralogy. These are based on data from experimental mechanical compaction of sands with different textural and mineralogical compositions. These data may help to predict properties of sandstones at a certain depth as a function of provenance and sedimentary facies.