Azimuthal AVO over a simulated fractured physical model medium

Faranak Mahmoudian, Gary F. Margrave, Joe Wong

We have verified the suitability of seismic data from a physical model for a quantitative amplitude analysis of anisotropic targets. Physical model data have often been used for traveltime analysis, while incorporating them in an amplitude analysis was limited due, in part, to the large size, highly-directional physical model transducers employed as sources and receivers. We acquired multi-offset, multi-azimuth, seismic data over a simulated fractured layer overlain by two isotropic layers with the most top layer being water. We simulated the fractured medium by constructing a physical layer, with horizontal transverse anisotropy (HTI), from phenolic material. Acquisition was designed to avoid the overlapping of the primary and ghost events. We treated the large-size transducers as seismic arrays and employed an array-type correction to compensate for their effects on seismic amplitudes. The PP reflection amplitudes from the top of the simulated fractured layer, after required AVO corrections, reveal a clear azimuthal variation caused by the simulated fractured layer and agreed with amplitudes predicted theoretically.