Abstract
Measurements of dynamic elastic properties of shale exhibit dispersion at seismic frequencies as well as between seismic and ultrasonic frequencies. We point to various possible dispersion mechanisms, including viscoelasticity of bound water in the narrow pores associated with clays and squirt flow associated with microcracks in non-clay and in elongated pores within the clay. The different mechanisms may be distinguished by combining rock physics models and laboratory experiments, forming a better foundation for seismic interpretation in subsurface shales.