Structural characteristics and deep-water hydrocarbon accumulation model of the Scotian Basin, Eastern Canada

Commercial hydrocarbon reservoirs have been discovered in shallow-water areas of the Scotian Basin, Eastern Canada. However, knowledge about the structure and hydrocarbon accumulation characteristics of the basin is still insufficient, which constrains the oil and gas exploration in deep-water areas. Based on comprehensive data of magnetic anomalies, seismic survey, and drilling, this study determines the structure characteristics of the Scotian Basin and its hydrocarbon accumulation conditions in deep waters and evaluates the deep-water hydrocarbon exploration potential. The transform faults and basement structures in the northern basin control the sedimentary framework showing thick strata in east and thin strata in west of the basin. The bowl-shaped depression formed by thermal subsidence during the transitional phase and the confined environment (micro basins) caused by salt tectonics provide favorable conditions for the development of source rocks during the depression stage (also referred to as the depression period sequence) of the basin. The progradation of large shelf-margin deltas during the drift phase and steep continental slope provide favorable conditions for the deposition of slope-floor fans on continental margins of the basin. Moreover, the source-reservoir assemblage comprising the source rocks within the depression stage and the turbidite sandstones on the continental margin in the deep waters may form large deep-water turbidite sandstone reservoirs. This study will provide a valuable reference for the deep-water hydrocarbon exploration in the Scotian Basin

Architecture and exploration target areas of the Senegal Basin, West Africa

The recent discovery of large oil and gas fields in the deep-water of the Senegal Basin has drawn global attention. Despite this, several exploration wells in this area fail, which can be primarily contributed to a lack of understanding of the basin's structures and hydrocarbon accumulation conditions. This study examines these characteristics utilizing gravity, seismic and drilling data, and finally makes a comparison with the Cote d’Ivoire Basin, a typical transform margin basin in the South Atlantic. The results suggest that the Senegal Basin, influenced by multiple transform faults and a weak Paleozoic basement, experienced three evolutionary stages: rifting, transitional, and drifting. Each stage contributed to the development of distinct depositional sequences - syn-rift sequences, sag sequences, and continental margin sequences, respectively. The Triassic - Early Jurassic rifting stage predominantly formed continental deposits, like fluvial, lacustrine, and deltaic deposits, in the syn-rift sequences. The Middle-Late Jurassic transitional stage, influenced by transform faults, witnessed the formation of marginal ridges or submarine uplift zones. These zones, in conjunction with landward high terrains, formed a restricted environment promoting the development of source rocks in the sag sequences. During the drifting stage, three types of reservoirs, namely platform carbonate rocks, deltas, and slope-floor fans were formed. Notably, large-scale hydrocarbon reservoirs have been found in the deltas and the slope-floor fans both in the Senegal Basin and the Cote d’Ivoire Basin. The Upper Jurassic - Aptian platforms exhibit thick carbonate rocks and organic reefs on their edges, suggesting substantial potential for hydrocarbon exploration in the Senegal Basin

Structural characteristics and exploration fields in passive continental margin basins of Central Atlantic

The petroleum resources of the passive continental margin basins in the Central Atlantic are rich, but the insufficient knowledge of basin structural characteristics and accumulation conditions in the area restricts the exploration of deepwater oil and gas. Based on the integral analysis of seismic, drilling, gravity anomalies and magnetic anomalies data, the basin structural characteristics and hydrocarbon accumulation conditions in deepwater area of the passive continental margin basins of the Central Atlantic are studied and the exploration fields are predicted with the Senegal and Scotia basins as key anatomical objects. It can be concluded that the passive continental margin basins of the Central Atlantic have experienced three evolution stages: the rift period, the transition period and the drift period, with corresponding development of three tectonic layers: the rift layer, the depression layer and the continental margin layer, and the basin structures are controlled by transform faults and basement properties. From Triassic to Early Jurassic rift period, a series of horst-graben structures were formed, and the sediments were mainly continental ones such as rivers, lakes and deltas. From Middle to Late Jurassic transition period, the marginal ridge or submarine uplift zone were developed due to the activity of transform faults, and a landward high terrain limited environment was formed due to the stretch, thinning and subsidence of the Paleozoic weak basement, providing a favorable condition for the development of source rocks in the depression layer. During Cretaceous drift period, platform margin reef and delta-slope floor fan reservoirs were developed. Both the deepwater slope floor fan in the Scotia Basin and the platform margin reef in the Senegal Basin have great exploration potential