Geostatistical Inversion of Seismic Data

Geostatisical inversion of seismic data, a novel acoustic impedance inversion technique. Is presented. illustrated by an example and discussed. The method generates 3D acoustic impedance models at the reservoir scale. These models can then be used for predicting reservoir properties such as lithology or porosity. Nonuniqueness of the inversion process is quantified by generating possible 3D acoustic Impedance realisations", all compatible with the acoustic Impedance traces at the wells. and the 3D seismic block. Vertical and horizontal continuity of these realisations Is constrained by means of an input vartogram model. Different geological scenarios can be generated, satisfying a given vartogram, and systematic vertical variations in acoustic impedance can be controlled by a vertical trend in the mean and standard deviation of acoustic impedance. Compared to existing stratigraphic inversion techniques. the main characteristic of the method is that acoustic impedance traces are generated sequentially: an objective function is minimised on a trace by trace basis instead of being minimised over the whole seismic block. This feature provides speed and flexibillty to the geostatistical inversion technique.