Keynote Presentation - Seismic Inversion and Fluid Classification at La Creciente and Rubiales Fields, Colombia

In Rubiales and other Llanos fields in Colombia, conditions are adequate for accurate mapping of lithology based on elastic inversion of seismic data and petrophysical estimation of shale volume fraction. We jointly estimate elastic isotropic medium parameters and mass density from inversion of seismic data, and characterized the sensibility of the parameters to the reservoir lithology, porosity and fluids. By means of various techniques of statistical inference we derived reliable estimation of shale volume fraction and total porosity, calibrated to well-log data. Sensitivity of the seismic data to fluids (heavy oil and brine) is smaller than for lithology at this field. A combination of spatial well information with elastic parameters obtained from the seismic inversion allows for an assertive inference of the spatial distribution of oil-sands. The oil-sand estimator showed positive agreement with the well-log information with more than 70% success in classification of oil-sand samples. The results of this study contributed to an accurate interpretation of the area and a 3D description of the reservoir, with a positive impact in the field development.