GEOSTATISTICAL RESERVOIR CHARACTERIZATION CONSTRAINED BY 3D SEISMIC DATA

Geostatistical inversion is developed for constraining a 3D geostatist ical realization of acoustic impedance using a 3D seismic block. The g eostatistical realization is constructed using a sequential variogram- based approach in such a way that the convolutional response of the re alization fits with the actual 3D seismic data. The method is illustra ted with a 3D synthetic example. The initial acoustic impedance model is generated using an unconditional simulation of one million grid cel ls. Then, using five wells 'drilled' in this model and the synthetic s eismic obtained by convolution, the geostatistical inversion method is applied to reconstruct the initial acoustic impedance model. The 3D s ynthetic seismic block is matched in a matter of half-an-hour CPU on a standard workstation. Analysis of the results shows that the input ge ostatistical model (variograms, means and standard deviations) control s the higher and lower frequencies that are not present in the seismic amplitudes. The use of a '3D earth modelling' tool allows efficient m anagement of the '3D earth model' constructed by geostatistical invers ion, and visualization of the various inputs and outputs.