Inversion with A Priori Information: A Step Toward Consistent and Integrated Interpretations of Reservoirs

J. Brac, P. Y. Dequirez, C. Jacques, P. Lailly, V. Richard, D. Tran Van Nhieu

We have designed a method to provide the interpreter with an acoustical impedance distribution such that (1) it matches the well logs exactly, (2) it fulfills the geological information (depositional environment, geometry of the faults, etc) specified by the interpreter, and (3) it best fits the associated synthetic seismic section with the stacked seismic section. Such an approach is especially suitable for interpolating or extrapolating well logs derived from seismic data and should ensure the consistency of the interpretations.

The methodology relies on a probabilistic formalism of inverse problems with a priori information. Here we solve a 2-D inverse problem, the forward problem being the convolution of reflection coefficients by the seismic wavelet. This approach is an example of integrating nonseismic data (well logs, geological information) within seismic data processing (stratigraphic deconvolution). It allows us to expect a deconvolution result with better stability and wider frequency bandwidth as well as improved signal-to-noise ratio.

The results for synthetic data confirm this expectation. Field data emphasize interpreters' interest in such an approach: easier and more reliable interpretation and the possibility to test geological assumptions and to describe a set of possible interpretations.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.