Rock Physics of the Eagle Ford Shale

The amplitude variation with offset (AVO) of seismic waves reflected from an interface between two geological layers is a function of the P-velocity, S-velocity, and density of the layers, and may be used to obtain information on lithology, porosity, fluid content, etc. Density, however, is often poorly resolved, and Debski and Tarantola (1995) showed that a parameterization of AVO in terms of P-impedance, S-impedance, and density is better than a parameterization in terms of P-velocity, S-velocity, and density, because uncertainty in the density estimate has larger impact on errors in estimates of Pand S-velocity than on errors in Pand S-impedance. For this reason, quantitative seismic interpretation makes use of rock physics templates formulated in terms of Pand Simpedance. In this paper, the ability of rock physics templates to distinguish between organic-rich and organiclean shales is investigated using log data from the Eagle Ford Shale, and the effect of kerogen on in-situ stress determination is discussed.