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Numerical simulation of ambient seismic wavefield modification.

Numerical simulation of ambient seismic wavefield modification caused by pore-fluid effects in an oil reservoir. 

 

Abstract

 

We have modelled numerically the seismic response of a poroelastic inclusion with proprieties applicable to an oil reservor thet interacts with an ambiend wavefiled. The model includes wave-induced fluid flow cause by pressure differences between mesoscopic-scale heterogenities.

 

We used a viscoelastic approximation on the macroscopic scale to implement the attenuation and dispertion resulting from this mesoscopic-scale theory in numerical simulations of wave propagation on the Kilometer scale.

 

This upscaling method includes finite-element modelling of wave induced fluid flow to determine effective seismic proprieties of the poroelastic media, such as attenuation of P- and S-Waves.

 

The fitted, equivalent, viscoeleastic behavior is implemented in finite-difference wave propagation simulation.

 

With this two sytage process, we model numerically the quasi-poroelastic wave-propagation on the kilometer scale and study the impact of fluid proprieties and fluid saturation on the modelled seismic amplitudes. Results indicates that ambient wavefield modification is expected to occur for oil reservoir exhibiting hight attenuation.

 

GEOPHYSICS VOL.78  NO.1