--> High Resolution Sequence Stratigraphic Framework of the Middle Tithonian – Lower Valanginian Interval (Vaca Muerta-Quintuco Formations), Neuquén Basin, Argentina

AAPG ACE 2018

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High Resolution Sequence Stratigraphic Framework of the Middle Tithonian – Lower Valanginian Interval (Vaca Muerta-Quintuco Formations), Neuquén Basin, Argentina

Abstract

In recent years, the exploration and development of the Vaca Muerta-Quintuco (middle Tithonian-lower Valanginian) mixed depositional system, have demonstrated to be an extraordinary unconventional world class shale gas-oil play, marking a turning point in the hydrocarbons history in Argentina. This behavior is the result of the combination of several factors, including: its excellent conditions as hydrocarbon-generating source rock, its lateral extension (>30000 km2), as well as its significant thickness -up to 600 m-.

In order to increase the understanding of the regional system, a 3D sequence stratigraphic framework has been constructed. A regional chronostratigraphic model has been built, using as inputs 9 regional surfaces interpreted from 3D/2D multi-surveys seismic volumes (~ 27000 km2) calibrated with more than 130 wells located across the basin. These key surfaces were correlated with outcrops and are interpreted as flooding zones and sequence boundaries. As a result, 4 low-frequency progradational northwestwards sequences have been identified.

Modeling also included a detailed analysis of depositional facies (2900 thin sections from cuttings) on a total of 20 wells distributed along both: dip/strike oriented transects that capture the main environmental variations of the units. In addition, we analyzed the regional changes of the main key components: a) textural, b) organic matter and c) skeletal abundance of the organisms present.

The aim of the study is to document vertical and lateral heterogeneities of the Vaca Muerta-Quintuco system captured and modeled at the basin scale. Internal variations of depositional facies within sequences were mainly controlled by: the northwest-ward progradational pattern, siliciclastic sediment input, climatic conditions and relative sea level changes during the Upper Jurassic-Lower Cretaceous period.