Estratigrafía y análisis de facies de la Formación Vaca Muerta en el área de El Trapial, Cuenca Neuquina, Argentina

Abstract

The Vaca Muerta Formation (early Tithonian - early Valanginian) is a lithostratigraphic unit in the Neuquén Basin, well known as a world-class source rock and for its unconventional resource potential. Vaca Muerta Formation in El Trapial block, northern Neuquén province, includes a remarkably thick organic-rich section (approximately 350 m) and a heterogeneous lithology. This study builds upon previous regional sequence stratigraphic interpretations and provides a refined stratigraphic framework for distal facies of Vaca Muerta Formation. The Quintuco - Vaca Muerta system in El Trapial shows at least twelve lithofacies that are grouped in three facies and two facies associations, interpreted as a lower mixed carbonate-siliciclastic ramp system which transitions to a more mixed-siliciclastic rich platform system. This core-interpreted succession shows a good correlation with outcrops located only 40 km West of the study area. Based on detailed facies analysis, petrographical/mineralogical descriptions, and biostratigraphy on core, core plugs, and well logs, five composite depositional sequences were identified, showing predominance on marlstones and mudstones for the transgressive cycles and carbonate facies in regressive cycles. By defining a local stratigraphic framework, tied to previous regional sequence stratigraphic interpretations, we were able to increase our unconventional reservoir predictability. A better understanding of the sequence stratigraphy and regional controls will lead to better planning and production of hydrocarbons within Vaca Muerta Formation through enhanced reservoir models and improved opportunity identification, reducing risks and costs.