Seismic Inversion with Quantification of Uncertainty - Case Studies from Clastic Basins

Reservoir description using seismic data has two major components: inversion of seismic data to extract attributes such as P- and S-wave velocities and bulk densities, and relate those parameters to reservoir properties, such as rock and fluid types, fluid saturation, porosity and pore pressure through fundamentals of rock physics. In seismic acquisition, we have seen considerable advancement that contributed to the quality of the seismic data, especially in the prestack domain. These are: single sensor recording (a large number of channels/offset), accurate and calibrated source and receivers and their positions, digital group forming, and towing cables at shallow water depths to minimize swell noise. All of these enable us to access surface seismic data with high S/N and fidelity that often rivals the fidelity of the Vertical Seismic Profiles (VSP). <br><br>In this paper, we use high quality seismic data to carry out Full Waveform Prestack Inversion to extract reservoir parameters, such as porosity and saturation. We use rock physics principles to constrain our inversion algorithm and then quantify our uncertainty using Bayesian approach that accounts for errors in upscaling and noise in the data and the model. We illustrate the entire procedure with examples from several basins.<br>