Reconciling Geology With Geophysics: Estimating a-Priori Facies Probabilities for Seismic Amplitudes Inversion Part 2, Case Study

This case study demonstrates a practical application of a geologically conditioned seismic amplitude inversion workflow. The applied method is based on a quantitative parameterization of a-priori geological knowledge where the diversity of sedimentary environments is described by a few statistically independent parameters (G-Factors). Interpolated values of G-Factors were used to estimate facies a-priori probabilities in the interwell space. The structural framework of the target interval was described with a probabilistic approach: for each elementary stratigraphic unit a probability cube was generated, which allowed taking into account kinematical uncertainties of seismic interpretation. Then a-priori lithotype probabilities as well as a-priori petrophysical properties distributions were estimated for each cell of the 3D grid. The integrated a-priori model was used to build a background model for seismic amplitude inversion as well as for quantitative interpretation of the inversion results.