Fracture characterization in Upper Permian carbonates in Spitsbergen: A workflow from digital outcrop to geo-model

Abstract

Carbonates represent major hydrocarbon reservoirs, but often exhibit highly heterogeneous reservoir properties. Outcrop analogues provide important insights into how parameters such as porosity, permeability and natural fractures vary. As such, outcrops can bridge the scale gap between spatially extensive but poor-resolution seismic data and 1D high-resolution well data. However, traditional geological fieldwork typically gathers insufficient data to construct robust geological models. In this study, we have specifically set out to gather key data sets that enable the construction of a geology-driven model. We illustrate this workflow using the exceptionally well- exposed carbonate-dominated outcrops of the Kapp Starostin Formation in central Spitsbergen, Arctic Norway. We fully utilize emerging technologies, notably geo-referenced digital outcrop models (DOMs), to be able to gather quantitative sedimentological-structural data from otherwise inaccessible cliffs. DOMs generated from digital photos are used directly for automatic and manual mapping of fractures. The digital data are com-plemented with traditional fieldwork (sedimentological logging, scanlines, structural characterization) in order to strengthen the dataset. The geo-modelling involves traditional facies and petrophysical modelling of the 12 identified facies, along with outcrop-based discrete fracture modelling. Finally, the static geo-model is upscaled, and its applications are discussed. The presented workflow uses carbonate outcrops of the Kapp Starostin For-mation as input but is highly applicable for other studies where outcrops can be utilized as direct input to constrain a geological model.