Geostatistical lithology modeling

Abstract

Lithology modeling is an essential part of quantitative reservoir characterization. Seismic data as well as geological information should be used to constrain the construction of lithology models. Geostatistics offers a number of tools to combine seismic and well log data with geological knowledge for the generation of detailed lithology models in association with other important reservoir parameters such as porosity and permeability. Simultaneous lithology and impedance simulation combined with goestatistical inversion gives excellent results but is computationally expensive. Cheaper techniques where the lithology models are simulated before or after impedance modeling do not produce equivalent results. Results from a carbonate reservoir show that all methods produce approximately the same total pore volume within the hydrocarbon interval. However, the simultaneous simulation with inversion produces models of the reservoir which have a much higher degree of heterogeneity. The lower connectivity between high porosity sweet spots has implications for field development.