A Revised Interpretation of Argentina’s Offshore Austral and Malvinas Basins and Petroleum Play Analysis

Abstract

The combined ~76,000 km2 of the Austral and Malvinas Basins of offshore Argentina share similar tectonic and stratigraphic histories. Whereas previous analyses and exploration efforts yielded positive results and existing data confirm a functional petroleum systems in the offshore. The petroleum exploration in the region is limited. In this study, we perform an updated evaluation using ~30,200 km of legacy 2D seismic data sourced from a range of vintages spanning from 1970 to 1998 in the Austral and Malvinas Basins. The primary objective of the study was to perform a comprehensive evaluation and assess the prospective areas that merit further exploration. The study area is situated entirely on Pre-Cambrian and Paleozoic continental basement in a region that has been subjected to periods of rifting, inversion, igneous activity. Since the Eocene a compressional foreland setting developed and transitioned into a transpressional setting during the Oligocene. The Austral and Malvinas Basins stratigraphic section is Upper Jurassic to Tertiary in age and consists of rift-related volcanic tuffs, fluvial deposits, and neritic-deeper marine deposits. The tectonic and stratigraphic evolutions are complex creating a variety of deformational features and depositional settings that are key components to the basin’s proven petroleum system in which all of the wells drilled in the study have hydrocarbon shows. A Lower Cretaceous source rock with recorded TOC values of 3-8% is mature for both oil and gas within the present-day foredeep. The Lower Cretaceous-Springhill sandstone is the principal exploration target for both basins and produces in several exploration wells. Younger Tertiary marine sandstones are generally isolated and serve as secondary reservoir targets. The analysis of these data confirm four distinct petroleum plays based on seismic facies and stratigraphic models: 1) the Scotian Foldbelt Play; 2) the Springhill structure play; 3) foredeep turbidite play; 4) Tertiary marine stratigraphic play. We present examples of potential exploration-play targets from seismic within the Austral and Malvinas Basins and relate them to well results and the thermal maturation model from the region.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018