Rock physics modelling in reservoirs within the context of time lapse seismic using well log data

Abstract

Rock physics provides a link between seismic and reservoir properties. It helps to understand the effects of fluid substitution and reservoir parameters on seismic signatures. Rock physics models are now an integral part of feasibility study of time lapse (4D) seismic surveys and their interpretation. There exist different approaches for the construction of rock physics models within the context of 4D seismic study. The objective of this study is to investigate the predictions of existing rock physics models for time lapse seismic studies using real well data. The pore-filled fluid properties used represent the in situ conditions, while the effective elastic moduli and bulk densities are calculated based on theoretical models. Finally the reflection and amplitude predictions from each model are compared over a range of water saturation. Our results suggest that only Krief’ s model is able to discriminate between porous and non-porous zones effectively. Furthermore, all of the investigated models show increase in velocity with replacement of oil with heavier fluid i.e., water except Wyllie’s model. There is a significant change in seismic amplitude when compared with in situ conditions for this particular lithology.