Seismic sensitivity to variations of rock properties in the productive zone of the Marcellus Shale, WV

Summary The productive zone of the Marcellus Shale has variations in rock properties such as clay content, kerogen content and aspect ratio of structural kerogen. These variations may also cause elastic anisotropy. We studied the seismic response of the Marcellus Shale for three types of models with variations in a specific parameter such as kerogen content, aspect ratio and anisotropic parameters. The reservoir was assumed transversely isotropic with vertical axis of symmetry (VTI). The seismograms were numerically simulated by applying a vertical impulse source and three component receivers. For kerogen content models, scenarios for 5%, 10%, 20% and 30% of kerogen in the host matrix were considered. For both kerogen content and aspect ratio models, PP amplitudes were most sensitive at zero to near offset while PS and SS amplitudes were most sensitive at mid offsets (12 to 30 degree angle of incidences).The anisotropic effect to angular amplitude variations for PP, PS and SS reflections were found to be dominantly controlled by the Thomsen Ɛ parameter. The anisotropic effect to PP data can be seen at large offsets (>15 o incidence angle). The most sensitive portion of PS reflections was observed at mid offsets (15 o -30 o ). The findings from these synthetic data may ultimately be applied to real data for the improved characterization of shale gas reservoirs.