Characterization of lower Vaca Muerta at Fortín de Piedra in Neuquén Basin, Argentina

Abstract

The Vaca Muerta Formation in the Fortín de Piedra Block is a current focus of exploration for hydrocarbons. Here, we investigate its deepest levels, La Cocina and El Orgánico. These levels have high average total organic content (TOC) of 4.5 and 3 wt%, respectively, making them the main exploration targets. Seismic stratigraphic interpretation indicates that La Cocina was deposited over a paleo-dune surface, initially covering it as a sheet but later forming discontinuous lenses as the interdune areas filled in. El Orgánico is an aggradational-progradational section, represented mainly by bottomset facies and subordinated foreset facies. The brittleness and TOC distribution, as correlated with well log and laboratory measurement data, suggest that the entire block is prospective for both levels.

The Vaca Muerta transgression (Upper Jurassic), Neuquén Basin, Argentina: Insights into the evolution and timing of aeolian–marine transitions

“…7B). Similar preservation of aeolian relief has been observed during different basin‐fill stages of the Neuquén Basin (Cevallos, 2005; Strömback et al., 2005; Reijenstein et al., 2014; Argüello‐Scotti & Veiga, 2015; Acevedo & Bande, 2018).…”

“…The current hypothesis for the Vaca Muerta Formation transgression envisages an instantaneous catastrophic Tithonian flooding preserving the aeolian fields (Mutti et al., 1994; Cevallos, 2005). This hypothesis relies on four main lines of evidence: (i) relative absence of onlap relationships to the underlying continental LST deposits (Cevallos, 2005); (ii) lack of transitional facies between the aeolian and marine deposits (Mutti et al., 1994); (iii) preservation of the underlying dune‐field topography indicating subordinate marine reworking (Cevallos, 2005; Reijenstein et al., 2014; Acevedo & Bande, 2018); and (iv) presence of soft‐sediment deformation structures in the upper part of the aeolian deposits (Cevallos, 2005; Veiga & Spalletti, 2007).…”

“…There, the upper beds of the aeolian Kimmeridgian deposits (Catriel Formation) show liquefaction structures generated by flooding over unconsolidated deposits (Cevallos, 2005). The megadune topographic relief is preserved below the transgressive surface (Cevallos, 2005; see also Reijenstein et al., 2014; Acevedo & Bande, 2018). Overlying the transgressive surface, the TST consists of a few centimetres to >10 m thick succession of marl, black mudstone and limestone with bivalve bioclasts and siltstone and fine‐grained sandstone intraclasts, named as the Rapid Transgression Remnant.…”