A big challenge in unconventional reservoir characterization is the understanding of reservoir heterogeneity and its impact on well productivity. At field scale it is critical to understand stratigraphic heterogeneity, as it affects reservoir and completion quality. Geographic heterogeneity, i.e. the variations associated to the paleogeography and the structural context of the area of interest, can be seen as a variable more linked to the exploration scale.
The results of a field-scale interdisciplinary study of the Quintuco-Vaca Muerta depositional system in the center of the Neuquén Basin (Argentina) reveal that the production potential of the Vaca Muerta unconventional reservoir is strongly affected by both, stratigraphic and geographic heterogeneity.
In the study area the Quintuco-Vaca Muerta system consists of a mixed clastic-carbonate succession deposited in a shallow to deep marine setting. The geometry of the system is characterized by the development of prograding clinoforms from southeast to northwest. The Vaca Muerta formation is composed primarily by intercalations of organic-rich calcareous shales, marls, and micritic limestones, deposited in a distal ramp to basin setting. The proportion and stacking pattern of these facies vary from southeast to northwest, following the geometry of the depositional system. This facies variation was captured using electrofacies derived from high resolution electrical logs and integrated with borehole images and acoustic data for the construction of 1D/2D geomechanical models.