AVO analysis and seismic inversion
Pre-stack seismic interpretation is a key element in many of our process chains. It begins with additional processing and linking of seismic data to wells and preliminary AVO analysis. To build a low-frequency model, we have developed a special approach where, along with well data, seismic velocities and deep trends in elastic properties are used. To invert 2D data, we also build an initial homogeneous model in 3D. For inversion, either angular sums or seismograms with kinematic correction are used. The resulting data are the acoustic and shear (elastic) impedances, the resulting Vp/Vs ratio, and, if available, the density. In many cases, conversion to LambdaRho-MuRho space results in better separation into target lithotypes.
For interpretation, along with cross-density methods, we use probabilistic classification of lithology and pore fluids based on stochastic models of elastic properties of rocks and taking into account deep compaction trends. As a result, we obtain probabilistic cubes of lithotypes (clay, water-saturated reservoir, hydrocarbon-saturated reservoir, etc.), which can be used to assess prospectivity, sequence stratigraphy, or as an additional trend in geological modeling.