ABSTRACT

Scattering of seismic waves may cause a significant amount of apparent attenuation, particularly in regions having strong heterogeneity. We find that the radiative transfer method can be used to model intrinsic and scattering attenuation of crosswell seismic data. To solve the radiative transfer equation, we assume that the medium can be described by a stationary random field and then we use a particle-based method in which millions of particles are released from a source and scatter through the random medium according to the Born scattering coefficients. Intrinsic attenuation is modeled by assigning probabilities that the particles will die off on the path between scattering events. We apply the seismic particle method to crosswell seismic data acquired on a carbonate reef in the Michigan Basin, and we use a grid search to estimate a set of model parameters that fit the data. Based on well logs, we fixed the velocity heterogeneity strength at 3% and estimated the medium velocity correlation length to be between a=0.5 and a=2  m. Our results also indicate that scattering attenuation is one order of magnitude larger than intrinsic attenuation, a result that we interpret as a consequence of the highly heterogeneous nature of the rock comprising the reservoir. Contrary to other attenuation estimation methods, such as the centroid method, in which scattering attenuation is neglected by invoking that the reservoir is homogeneous, our results indicate that accounting for scattering attenuation is of paramount importance in attenuation estimation using crosswell seismic data.

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