Rock physics based probabilistic lithology and fluid prediction in a heterogeneous carbonate reservoir

摘要

The deep-buried Paleozoic marine carbonate reservoirs of Sichuan Basin, SW China, exhibit strong heterogeneities due to complicated diagenetic processes. The goal of our work is to map posterior probabilities of lithology and fluid based on seismic and well observations in this reservoir, thus helping characterize reservoir complexity. Rock physics study gives physical insight on how the elastic properties of different litho-fluid classes can be distinguished. Bayesian linearized AVO inversion results indicate that the posterior distribution of P-wave and S-wave velocity are confidently extracted, while the inverted density tends to show high uncertainty due to a lack of wide angle of seismic data. Finally, a full Bayesian approach was implemented to propagate uncertainty from prestack seismic data to assess posterior probabilities of litho-fluid classes in an integrated framework.