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Reservoir Modeling of Small-Scale Heterogeneities in Channelized Turbidite Systems: Digital Outcrop Studies of the Ross Formation, SW Ireland*

By

Cathrine Pedersen¹, John Howell², Trond Lien¹,  Ellinore Bjørk Vipond¹, John Thurmond¹, Tore Løseth¹, and Ole Martinsen¹

Search and Discovery Article #40267 (2007)

Posted November 25, 2007

*Adapted from extended abstract prepared for presentation at AAPG Annual Convention, Long Beach, California, April -4, 2007

¹Hydro Oil & Energy, Bergen, Norway ([email protected])

²University of Bergen, CIPR, Bergen, Norway

Abstract 

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 (Figure 1). 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 (Figure 2). 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.