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dc.contributor.advisorGrundvåg, Sten-Andreas
dc.contributor.authorHagset, Andreas Hallberg
dc.date.accessioned2023-04-12T08:53:55Z
dc.date.available2023-04-12T08:53:55Z
dc.date.issued2023-04-20
dc.description.abstractAcross the Norwegian Continental Shelf (NCS), the Upper Jurassic organic-rich shales are considered the main source rock unit charging most of the largest producing oil and gas fields. However, despite its extensive distribution across the NCS, this source rock unit is overmature and spent in the deep Cretaceous basins on the mid-Norwegian margin and the SW Barents Shelf. Documenting the presence of alternative source rock units at stratigraphic shallower intervals is therefore crucial for exploration success in these frontier areas. Such alternative source rock units may amongst others occur in the Lower Cretaceous or younger successions. The main objective of this study is thus to establish the presence, spatial variations, depositional conditions, and petroleum potential of Cretaceous organic-rich units on the NCS, particularly focusing on the deep Cretaceous basins along its rifted western margin. From south to north, the main study areas are confined to the mid-Norwegian margin (Paper II), the SW Barents Shelf (Paper I), and Svalbard (Paper III), the latter representing the exhumed NW corner of the NCS. This study utilizes high-quality regional 2D reflection seismic data, wireline logs, and an extensive geochemical database, all combined to assess and elucidate the petroleum potential of several organic-rich units recognized in the Lower Cretaceous of the study areas. This integrated dataset forms the basis for conceptual models made specifically for each region which host organic-rich units with generation potential. These models emphasize changing depositional conditions and factors that controlled the development and preservation of the various organic-rich units, including regional rift-related tectonics and global anoxic events. The lateral distribution of the organic-rich units is also discussed with respect to the regional tectonic evolution of the NCS during the Cretaceous, and their potential is established through traditional source rock evaluation.en_US
dc.description.doctoraltypeph.d.en_US
dc.description.popularabstractThe deep basins on and along the margin of the Norwegian Continental Shelf (NCS) formed during the progressive fragmentation of Pangea c. 145 million years ago. Following these basin-forming events, organic-rich sediments, which form so-called source rocks, was deposited. It is these sediments that have generated much of the petroleum on the NCS. However, as mud and sand filled up the basins over millions of years, the organic-rich sediments were buried at continuously deeper depths, down to a point were eventually all organic matter was burnt off due to high temperatures. Thus, to find new resources in areas where this have happened, exploration success depends on the occurrence and recognition of organic-rich sediments located at shallower depths in the subsurface where temperatures are more optimal for petroleum generation. Such alternative units may occur at multiple levels in the younger parts of the offshore sedimentary rock record, such as within the Cretaceous succession. The main objective of this study is thus to document and map the occurrence of organic-rich sediments of Early Cretaceous age and evaluate their petroleum potential. This is done by using seismic and geochemical data. Four organic-rich units have been recognized in the Lower Cretaceous succession of the NCS which all have variable petroleum potential and scattered distribution. We demonstrate that their occurrence and potential was governed by the restricted nature of the basins, variable oxygen content in the water column, and how fast and at which rate other sediments entered the basin and buried the organic-rich sediments.en_US
dc.description.sponsorshipThe PhD project was fully funded by Wintershall-Dea.en_US
dc.identifier.isbn978-82-8236-520-8 (print)
dc.identifier.isbn978-82-8236-521-5 (pdf)
dc.identifier.urihttps://hdl.handle.net/10037/28953
dc.language.isoengen_US
dc.publisherUiT Norges arktiske universiteten_US
dc.publisherUiT The Arctic University of Norwayen_US
dc.relation.haspart<p>Paper I: Hagset, A., Grundvåg, S.A., Badics, B., Davies, R. & Rotevatn, A. (2022). Tracing Lower Cretaceous organic-rich units across the SW Barents Shelf. <i>Marine and Petroleum Geology, 140</i>, 105664. Also available in Munin at <a href=https://hdl.handle.net/10037/24708>https://hdl.handle.net/10037/24708</a>. <p>Paper II: Hagset, A., Grundvåg, S.A., Badics, B., Davies, R. & Rotevatn, A. (2023). Deposition of Cenomanian – Turonian organic-rich units on the mid-Norwegian Margin: controlling factors and regional implications. <i>Marine and Petroleum Geology, 149</i>, 106102. Also available in Munin at <a href=https://hdl.handle.net/10037/28745>https://hdl.handle.net/10037/28745</a>. <p>Paper III: Hagset, A., Grundvåg, S.A., Wesenlund, F., Badics, B. & Thießen, O. Source rock evaluation of Hauterivian-Barremian (Early Cretaceous) paralic deposits in Svalbard. (Manuscript).en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2023 The Author(s)
dc.subject.courseIDDOKTOR-004
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450::Petroleum geology and petroleum geophysics: 464en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Petroleumsgeologi og -geofysikk: 464en_US
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450::Marine geology: 466en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Marin geologi: 466en_US
dc.titleSeismic characterization and source rock evaluation of Lower Cretaceous organic-rich units on the Norwegian Continental Shelfen_US
dc.typeDoctoral thesisen_US
dc.typeDoktorgradsavhandlingen_US


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