Extensive Broadband 3D Seismic to De-risk and Mature the West of Shetland Exploration Portfolio

84th EAGE Annual Conference &Amp; Exhibition

Jolley

et al. 2023

The Faroe-Shetland Basin (FSB) is one of the only significant exploration frontiers remaining on the UK Continental Shelf. Over half of the basin's discovered reserves and resources lie along two intra-basinal highs, the Corona Ridge and the Rona Ridge. In contrast to the Rona Ridge, the central-northern Corona Ridge has received much less attention.To reveal new insights into the geology, structural configuration and hydrocarbon prospectivity of the central-northern Corona Ridge, we analyse 3D seismic data and data from the exploration wells 213/23-1 (Eriboll), 214/21a-2 (South Uist) and 213/25c-1V (North Uist). This study extends the Colsay T40-T45 sub-and intra-basaltic play concept from the Rosebank Field NE along the Corona Ridge, at least into well 213/23-1. Analysis also suggests that no Triassic strata are present within well 213/23-1, challenging the previous understanding of Triassic distribution within the central FSB. Our findings show that the centralnorthern Corona Ridge is structurally complex, comprising a series of discrete basement-bounding faults, downflank fault terraces and faults that are oblique to the dominant NE-SW-striking structural fabric of the FSB.

Section: Methodsmentioning

confidence: 99%

New insights into the structure, geology and hydrocarbon prospectivity along the central-northern Corona Ridge, Faroe–Shetland Basin.

84th EAGE Annual Conference &Amp; Exhibition

Jolley

et al. 2023

3D Seismic reflection evidence for lower crustal intrusions beneath the Faroe–Shetland Basin, NE Atlantic Margin

Watson

et al. 2023

JGS

Lower crustal intrusion is considered a common process along volcanic or magma-rich passive margins, including the NE Atlantic Margin, where it is considered to have occurred during phases of Paleogene magmatism, prior to and during continental break-up between NW Europe and Greenland. Evidence of Paleogene magmatism is prevalent throughout the sub-basins of the Faroe-Shetland Basin (FSB) as extensive lava flows and pervasive suites of igneous intrusions. However, in contrast to other areas located along the NE Atlantic Margin, no lower crustal reflectivity indicative of lower crustal intrusions has been documented beneath the FSB. The nearest documentation of lower crustal reflectivity and interpretation of lower crustal intrusions to the FSB is NW of the Fugloy Ridge, beneath the Norwegian Basin of the Faroese sector. Despite this, the addition of magma within the lower crust and/or at the Mohorovičić discontinuity is thought to have played a role regarding Paleogene uplift and the subsequent deposition of Paleocene-Eocene sequences. Advances in sub-basalt seismic acquisition and processing have made significant improvements in facilitating the imaging of deep crustal structures along the NE Atlantic Margin. This study uses broadband 3D seismic reflection data to map a series of deep ( c. 14 to 20 km depth) high-amplitude reflections which may represent igneous intrusions within the lower crust beneath the central-northern Corona Ridge. We estimate that the cumulative thicknesses of the reflections may be over 5 km in places, which is consistent with published values of magmatic underplating within the region based on geochemical and petrological data. We also estimate that the total volume of lower crustal high-amplitude reflections within the 3D dataset may be over 2000 km 3 . 2D gravity modelling of a seismic line located along the central-northern Corona Ridge supports the interpretation of lower crustal intrusions beneath the central-northern Corona Ridge. This study provides evidence of a potential mechanism for Paleogene uplift within the region. If uplift occurred as a result of lower crustal intrusions emplaced within the crust during the Paleogene, based on previous work, we estimate that around 300 m of uplift may have been generated within the Corona Ridge area.

New insights into the structure, geology and hydrocarbon prospectivity along the central-northern Corona Ridge, Faroe–Shetland Basin

Jolley

et al. 2022

The Faroe–Shetland Basin (FSB) is one of the only significant exploration frontiers remaining on the UK Continental Shelf. Over half of the basin's discovered reserves and resources lie along two intra-basinal highs, the Corona Ridge and the Rona Ridge. In contrast to the Rona Ridge, the central-northern Corona Ridge has received much less attention. To reveal new insights into the geology, structural configuration and hydrocarbon prospectivity of the central-northern Corona Ridge, we analyse 3D seismic data and data from the exploration wells 213/23-1 (Eriboll), 214/21a-2 (South Uist) and 213/25c-1V (North Uist). This study extends the Colsay T40–T45 sub- and intra-basaltic play concept from the Rosebank Field NE along the Corona Ridge, at least into well 213/23-1. Analysis also suggests that no Triassic strata are present within well 213/23-1, challenging the previous understanding of Triassic distribution within the central FSB. Our findings show that the central-northern Corona Ridge is structurally complex, comprising a series of discrete basement-bounding faults, downflank fault terraces and faults that are oblique to the dominant NE–SW-striking structural fabric of the FSB.