Ultrasonic and Numerical Modeling of Reflections from Simulated Fractured Reservoirs

Vve examine seismic waves scattered from anisotropic heterogeneity with laboratory data and numerical modeling in order to develop modeling techniques for the characterization of fracture p'roperties in tight gas sands from surface seismic reflection data. Laboratory models representing features of a fractured reservoir were constructed using Phenolite (the "reservoir") embedded in a Lucite background, and seismic surveys were gathered over these models. In parallel with laboratory measurements, finite-difference modeling of reflections from a fractured medium were carried out. Fracture zone properties were calculated using an effective medium theory; the variation of fracture density produced a heterogeneous medium. The heterogeneity was modeled with a stochastic process, characterized by a probability density function and an auto-correlation function. Results from both modeling efforts show that prestacked AVO data can contain important information describing reservoir heterogeneity.