A Seismic Reservoir Characterization Work Flow for Reducing Risk Utilizing AVO, Simultaneous Prestack Inversion, and Rock Physics

摘要

In this paper, an integrated seismic-based reservoir characterization, work. flow is presented which includes fluid substitution, AVO modeling, prestack simultaneous inversion, and lithology and petrophysi-cal property prediction. Forward modeling is normally the most effective way to commence an AVO analysis, which begins with determining the fluid response by calculating seismic velocity and offset-dependant reflectivity changes due to different fluid saturations. The investigation of amplitude variations with offset seeks to extract information about the reservoir rock by measuring changes in amplitude with varying incident angle. Next, the seismic data are analyzed in order to determine whether a conditioning process must be implemented to extract the most out of the seismic data. The aim is to preserve the AVO response while flattening events as much as possible as well as adequately attenuating noise without generating artifacts. Prestack simultaneous AVO inversion follows seismic conditioning, where the data are converted from interface properties to layer properties by the use of a global optimization algorithm with a nonlinear cost function to simultaneously invert a number of input stacks to an earth model. The final process in the characterization work flow is determining a spatial distribution of lithology and petrophysical properties based on rock physics and Bayesian statistics using the acoustic and elastic output volumes from the simultaneous inversion.