Basin evolution, configuration styles, and hydrocarbon accumulation of the South Atlantic conjugate margins

Abstract

The basins of the South Atlantic passive margins are filled with early rifting stage lacustrine sediments (Barremian, 129-125 Ma), transitional lacustrine and marine sediments (Aptian, 125-113 Ma), and drift stage marine sediments since early Cretaceous (Albian, 113 Ma). The South Atlantic margins can be divided into three segments by the Rio Grande Fracture Zone and the Ascension Fracture Zone according to variations in the basin evolution history and configuration style. The lacustrine shale and marine shale source rocks are developed in the rift stage and drift (post-rift) stage in the South Atlantic passive margins, respectively. The southern segment of the margins is dominated by the lacustrine sedimentary filling in the rifted stage overlain by a thin marine sag system as a regional seal, where the hydrocarbons are mainly accumulated in the structural-stratigraphic lacustrine reservoirs formed in the rift stage. The middle segment developed salty rift-sag-type basins with rift and sag systems and with salt deposited in the transitional intercontinental rift stage, where the lacustrine shale in the lower part of the rifted lacustrine sequence and the marine shale in the lower part of the sag sequence formed in the marine post-rift stage are high-quality source rocks. This segment in the middle is mainly dominated by pre-salt lacustrine carbonate and post-salt marine turbidite plays. The northern segment is characterized by sag-type basins with a narrowly and locally distributed rifted lacustrine system and its overlying widely distributed thick marine sag systems. Gravity-flow (mostly turbidite) marine sandstones as good reservoirs were extensively developed in the sag stage due to the narrow shelf and steep slope. The post-rift marine shales in the lower part of the sag

Characterising the internal structural complexity of the Southern North Sea Zechstein Supergroup Evaporites

“…However, improvements in the seismic processing of evaporite sequences are leading to coherent reflectivity within these formations, potentially leading to an evolution in the interpretation of evaporite sequences' internal structural heterogeneity. Much of the current understanding of evaporite sequences has come from their association and the subsequent data acquisition with prolific hydrocarbon provinces, such as the Precaspian Basin (Rowan et al, 2019), the South Atlantic conjugate margins (Blaich et al, 2008;Wen et al, 2019), the Zagros basin (Amthor et al, 2005;Bordenave & Hegre, 2010) and the North Sea (Peryt et al, 2010), where sequences are important for both trapping geometries and seals (Archer et al, 2012;Sarg, 2001). Similarly, evaporite formations will likely be important components in many subsurface developments required for the energy transition, in particular for geological storage sites (Duffy et al, 2023).…”

Characterising the internal structural complexity of the Southern North Sea Zechstein Supergroup Evaporites

“…Much of the current understanding of LES has come from their association with prolific hydrocarbon provinces, such as the Gulf of Mexico (Weimer et al, 2017), the Nile Delta (Aal et al, 2000), the South Atlantic conjugate margins (Wen et al, 2019) and the North Sea (Peryt et al, 2010), where sequences are important for both trapping geometries and seals (Archer et al, 2012, Sarg, 2001. Similarly, LES have been utilised for the development of underground caverns storing principally oil and natural gas (Tarkowski and Czapowski, 2018).…”