Geological and near-surface geophysical data comparison helps integration of outcrop and subsurface data for fractured carbonate reservoirs description. 9th Middle East Geosciences Conference, GEO 2010.

Abstract

The heterogeneity of fractured carbonate reservoirs invariably controls their flow performance and economic value. Depositional facies, diagenesis and fractures, their distribution, spatial and genetic relationships are the sources of the heterogeneity of storage and flow properties within these reservoirs. Understanding such spatial and genetic relationships between sedimentary facies, diagenesis and fractures is fundamental to adequately describe fractured carbonate reservoirs, model their dynamic performance and identify the most appropriate development and management strategies. Particularly for fractured carbonates, outcrops are essential sources of information, in three-dimensions and at a wide range of scales, for making plausible and useful descriptions of the elements listed above. The challenge remains the effective use of outcrops in a subsurface modelling project where the co-located information are wellbore and seismic data. We aim to tackle this challenge starting from comparing the different information provided by direct geological observation and remote sensing and the different models resulting from using one or the other dataset in isolation. We have selected a large quarry excavated within shallow water Cretaceous carbonates of the Apulian platform in the Italian Apennines foreland where the two datasets have been acquired. Geological (sedimentological, diagenetic, structural) data obtained from direct and detailed outcrop observations and measurements provide the means for building a detailed, geologically consistent 3-D model through interpolation between available 2-D exposures. Geophysical data consisting of a 3-D survey and 2-D lines acquired using ground-penetrating radar (GPR), provides more spatially continuous (albeit lower resolution and at times geologically inconsistent) geometric information. Comparison between the models resulting from the two different datasets highlights some important pitfalls related to scale, resolution, interpolation and extrapolation assumptions that modellers invariably have to make when building reservoir models with detrimental effects to the usefulness of these as prediction tools. This work provides insights on the modes of integrating outcrop and subsurface datasets for building fractured carbonate reservoirs models.