Characterizing permeability-controlling fracture attributes is essential for well planning and stimulation design, especially in unconventional reservoirs. Outcrops allow to measure fracture attributes that are below seismic resolution or cannot be readily sampled by core, such as fracture height and length. For outcrops to be useful analogs to the subsurface, however, fractures in outcrop must be representative of those in the buried reservoir rocks. Here we show that fractures in Vaca Muerta Formation outcrops in the Agrio fold-and-thrust belt have similar characteristics to those in the subsurface reservoirs in the Neuquén basin. Because of this close correspondence between fractures in core and in the Loncopué outcrops, fracture attributes (height, length, aperture, intensity, spacing) measured in outcrop may be used as a proxy to populate DFN models. Most fractures are infilled by blocky and/or fibrous calcite cement and densities are low, therefore present-day fluid flow through natural fractures is likely to be limited but likelihood of reactivation of preexisting natural fractures by hydraulic fractures is potentially high.


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