AVO Monitoring of CO[subscript 2] Sequestration

Abstract

Standard geophysical methods for monitoring CO[subscript 2] injection have been proposed but many have severe limitations. In particular, while they can be used to monitor the presence or absence of CO[subscript 2] during an injection, they are unable to quantify changes in CO[subscript 2] saturation in most reservoirs. Amplitude versus Offset (AVO) attributes may be able to provide more sensitive discriminators for CO[subscript 2] presence. We propose a workflow useful for the prediction of the AVO response under arbitrary geologic conditions. Using this method we perform an experiment where AVO is combined with an upscaling scheme that propagates the effects of small-scale heterogeneities up to the scale of seismic observation. This experiment demonstrates the ability of the AVO technique to not only determine the presence or absence of CO[subscript 2], but also to determine the degree of CO[subscript 2] saturation in the reservoir.