The movement of magma through the shallow crust and the impact of subsurface sill complexes on the hydrocarbon systems of prospective sedimentary basins has long been an area of interest and debate. Based on 3D seismic reflection and well data, we present a regional analysis of the emplacement and magmatic plumbing system of the Palaeogene Faroe-Shetland Sill Complex (FSSC), which is intruded into the Mesozoic and Cenozoic sequences of the Faroe-Shetland Basin (FSB). Identification of magma flow directions through detailed seismic interpretation of approximately 100 sills indicates that the main magma input zones into the FSB were controlled primarily by the NE-SW basin structure that compartmentalise the FSB into its constituent sub-basins. An analysis of well data shows that potentially up to 88% of sills in the FSSC are <40 m in thickness, and thus below the vertical resolution limit of seismic data at depths at which most sills occur. This resolution limitation suggests that caution needs to be exercised when interpreting magmatic systems from seismic data alone, as a large amount of intrusive material could potentially be missed. The interaction of the FSSC with the petroleum systems of the FSB is not well understood. Given the close association between the FSSC and potential petroleum migration routes into some of the oil/gas fields (e.g. Tormore), the role the intrusions may have played in compartmentalisation of basin fill needs to be taken fully into account to further unlock the future petroleum potential of the FSB.

Igneous sills and dykes that intrude pervasively into prospective sedimentary basins are a common occurrence in volcanic rifted margins, impacting the petroleum system and causing geological and technical drilling challenges during hydrocarbon exploration. The Faroe-Shetland Basin (FSB), NE Atlantic Margin, has been the focus of exploration for over 45 years, with many wells penetrating igneous intrusions. Utilising 29 FSB wells with 251 intrusions and 3D seismic data, this study presents new insights into the impacts that igneous intrusions have on hydrocarbon exploration. Examination of cores reveals that there can be up to 35% additional igneous rock in individual wells compared to estimates using seismic or petrophysical data alone, leading to potential underestimation of the igneous component in a basin. Furthermore, analysis of petrophysical data shows that within the FSB there are evolved intrusions such as diorite and rhyolite in addition to the commonly encountered basaltic intrusions. These evolved intrusions are difficult to recognise in seismic and petrophysical data and have historically been misidentified on seismic as exploration targets. Drilling data acquired through intrusions provide valuable insight into the problems exploration wells can encounter, often unexpectedly, many of which can be detrimental to safe drilling practice and result in prolonged nonproductive time.

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The UK Rockall Basin is one of the most underexplored areas of the UK Continental Shelf (UKCS), with only 12 exploration wells drilled since 1980. With only one discovery made in 2000 (Benbecula (154/1-1) gas discovery), the general view of the basin from an exploration viewpoint is not positive. However, over the last 15 years, our knowledge of the petroleum systems of the Atlantic Margin has substantially increased. With the recent acquisition of new seismic data by the UK Government as part of the OGA's Frontiers Basin Research Programme, it is a pertinent time to re-examine the prospectivity of the UK Rockall Basin.This paper presents a history of exploration within the UK Rockall Basin, from the first well drilled in the basin in 1980, to the last well, drilled in 2006. We then present new insights into the lack of success during exploration within the basin, in particular by focusing on the extensive Early Cenozoic volcanic rocks within Rockall, to illustrate the wide range of potential interactions with the petroleum system. We also present evidence that points to the potential of a viable intra-basaltic (Rosebank) type play along the eastern flank of the Rockall Basin.

Determining the burial and strain history of sedimentary rocks is important for understanding crustal behaviour. When rocks contain organic carbon, increased temperatures at depth can alter the molecular structure of the carbon. This change, known as carbon ordering, can be detected using Raman spectroscopy. As a result, Raman spectroscopy is increasingly used to estimate burial depths and associated maximum temperatures in carbon-bearing rocks. It is known from experiments and natural samples that other factors can affect Raman-derived maximum temperatures, including frictional heating on fault planes and interaction with hot fluids. For faulted samples, a question remains as to whether it is purely frictional heating that causes carbon ordering or strain, or a combination of the two. In this study, we use a mid-crustal shear zone to show that strain-related carbon ordering occurs in natural rock samples during aseismic shear strain. A traverse across the shear zone, whose relative strain we quantify with respect to the surrounding less deformed rock, shows a marked decrease in Raman D/G peak intensity ratios indicating greater carbon ordering within the shear zone. We interpret this as evidence for carbon ordering as a result of aseismic shear strain, rather than inflated temperatures, due to frictional heating commonly associated with seismic strain rates on faults. Our results have implications for the further development of Raman spectroscopy as a geothermometer (which may yield erroneous results in strained rock samples) and for understanding strain localisation processes in the Earth's crust, and its associated rheological implications.