Reservoir Modelling of Small-Scale Heterogeneities in a Channelized Turbidite Systems: Digital Outcrop Studies of the Ross Formation, Western Ireland

Pedersen, Cathrine¹, John Howell², Trond Lien³, Ellinore Bjoerk Vipond⁴, John Thurmond³, Tore Løseth³, Ole Martinsen⁵ (1) University of Bergen, Norsk Hydro, Bergen, Norway (2) University of Bergen, Bergen, Norway (3) Hydro Oil & Energy Research Center, Bergen, Norway (4) University of Bergen / Norsk Hydro, Bergen, Norway (5) Hydro Oil & Energy Research Centre, N-5020 Bergen, Norway

Deep-water channelized turbidite deposits represent architecturally complex hydrocarbon reservoirs, especially at the facies scale. Due to resolution of seismic and core/log-data, the population of coarse flow simulation grid cells with realistic and effective permeabilities is a key challenge for reservoir modeling.

Facies architecture data from outcrops bridge the scale gap between seismic data and well data. By building small (50x50x2-6m), detailed (>0.02m vertical resolution) and accurate facies-based reservoir models of outcrops (“simulation cell mini-models”), it is possible to bridge the gap between core/log-data and field scale simulation models. The accurate representation of the facies architecture in these small-scaled models produces a geometric framework, within which sensitivity testing can be conducted.

The models presented were built from the Carboniferous Ross Formation in County Clare, Ireland. Photorealistic mapping was used to create a virtual outcrop model from which the geometric data, necessary to create the structural framework for a series of simulation cell mini-models, were extracted. The three-dimensional digital outcrop was supplemented by traditional section logging techniques and several 2-D ground-penetrating radar lines. All of the collected information has been included into the reservoir models, providing detailed 3D representation of the facies architecture within channel spillover-overbank deposits and channel fill deposits.

The detailed models were subsequently upscaled to one single simulation grid cell using different upscaling methods, which were then compared to each other. The results of this study produced effective permeability estimates and represent improved input values for the single simulation grid cells in a larger-scale flow simulation.