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Session:

Petroleum 2

Abstract No.:

O-032

Title:

Geostatistical Inversion of Prestack Seismic Data

Author(s):

Ruben Filipe Martins Nunes, Instituto Superior Técnico (PT)
A. Soares, Instituto Superior Técnico (PT)
G. Schwedersky, Petrobras (BR)
L. Dillon, Petrobras (BR)
L. Guerreiro, Partex (PT)
H. Caetano , Partex (PT)
C. Maciel, Partex (PT)
F. Leon, Partex (PT)

Abstract:

This paper presents a method for geostatistical inversion of prestack seismic data to obtain P-wave and S-wave impedances (Ip and Is, respectively) and access the uncertainty of estimates. This is a generalization, to prestack seismic data, of basic principles of geostatistical inversion with a global perturbation method. To solve the inversion problem, geostatistical methods of direct sequential simulation and co-simulations are used as perturbation methods, to generate images of impedances in an iterative approach to successful converge to the match of an objective function of the real seismic and synthetic seismogram. The algorithm is implemented using Fatti?s equation, based upon Aki-Richards approximation, thus assuming that the angle-dependent reflectivity is independent of density, which simplifies the problem. To characterize simultaneously the P-impedance and S-impedance, keeping the data relations observed at the wells, a new algorithm based on the method of co-simulation with bi-distributions is presented. The application of this methodology is illustrated with a synthetic dataset, allowing quantification of the mismatch between inverted Ip and Is and the ?real? models. The method can be used to combine Ip and Is models to derive other elastic parameters.