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==Introduction==

==Introduction==

The South Viking Graben (SVG), in the northern part of the [[North Sea]], is a well-studied Middle to Upper [[Jurassic]] [[rift basin]] containing a major [[hydrocarbon province]] that extends across the border between the [[United Kingdom]] and [[Norway]]. Thermal doming during the [[Toarcian]]–[[Aalenian]], centered on the area south of the southern end of the SVG, resulted in the deposition of thick Middle Jurassic sequences along a north-trending basin that is now the SVG (Underhill and Partington, 1993<ref name=Underhillandpartington1993>Underhill, J. R., and M. A. Partington, 1993, Jurassic thermal doming and deflation in the North Sea: Implications of the sequence stratigraphic evidence, in J. R. Parker, ed., Petroleum Geology of Northwest Europe: Proceedings of the 4th Conference: Geological Society (London) Conference Series 4, p. 337–345.</ref>; and see Hoth et al., 2018<ref name=Hothetal201>Hoth, S., D. Knaust, A. Sánchez-López, S. Kassold, and S. Sviland-Østre, 2018, [http://archives.datapages.com/data/specpubs/memoir115/data/387_aapg-sp2050387.htm The Gudrun field: Gravity-flow deposition during rifting and inversion]], in C. C. Turner, and B. T. Cronin, eds., Rift-related coarse-grained submarine fan reservoirs; the Brae Play, South Viking Graben, North Sea: [http://store.aapg.org/detail.aspx?id=1301 AAPG Memoir 115], p. 387–422.</ref>). Subsequent deflation of the dome was followed by significant [[rift]]ing in the SVG, which began in the [[Callovian]]. However, the most active phases of rifting occurred during the [[Oxfordian]] to early [[Volgian]] (early [[Tithonian]]), when very thick [[synrift]] sequences were deposited in the graben. The graben is bounded on the west by the Fladen Ground Spur (FGS) and on the east by the Utsira High ([[:file:M115CH02FG01.jpg|Figure 1]]). A large proportion of the [[hydrocarbon]] reserves is found in synrift to early [[postrift]], deep-marine [[clastic]] [[sediment]]s of the [[Brae Formation]]; these accumulations are informally termed the [[Brae Play]]. The Brae Formation [[interfinger]]s with, and is overlain by, the [[Kimmeridge Clay Formation]] (KCF; termed [[Draupne Formation]] in Norway). The KCF-Draupne Formation is the major [[source rock]] and is the most significant [[seal]] for trapped Brae Play hydrocarbons. Several previous publications have shown the outlines and general internal structure of this buried half-graben (e.g., Harris and Fowler, 1987<ref name=Harrisandfowler1987>Harris, J. P., and R. M. Fowler, 1987, Enhanced prospectivity of the Mid-Late Jurassic sediments of the South Viking Graben, northern North Sea, in J. Brooks and K. Glennie, eds., Petroleum Geology of North West Europe: Bath, U.K., Graham and Trotman, p. 879–898.</ref>; Johnson et al., 1993<ref name=Johnsonetal1993>Johnson, H., P. C. Richards, D. Long, and C. C. Graham, 1993, United Kingdom offshore regional report; the geology of the northern North Sea: London, HMSO, for the British Geological Survey.</ref>; Sneider et al., 1995<ref name=Sneideretal1995>Sneider, J. S., P. de Clarens, and P. R. Vail, 1995, Sequence stratigraphy of the Middle to Upper Jurassic, Viking Graben, North Sea, in R. J. Steel, V. L. Felt, E. P. Johannessen, and C. Mathieu, eds., Sequence stratigraphy on the Northwest European margin: Norwegian Petroleum Society Special Publication 5, p. 167–197.</ref>; Thomas and Coward, 1996<ref name=Thomasandcoward1996>Thomas, D. W., and M. P. Coward, 1996, Mesozoic regional tectonics and South Viking Graben formation: Evidence for localized thin-skinned detachments during rift development and inversion: Marine and Petroleum Geology, v. 13, p. 149–177.</ref>; Fraser et al., 2003<ref name=Fraseretal2003 />; Zanella and Coward, 2003<ref name=Zanellaandcoward2003>Zanella, E., and M. P. Coward, 2003, Structural framework, in D. Evans, C. Graham, A. Armour, and P. Bathurst, eds., The Millennium Atlas: Petroleum geology of the central and northern North Sea: Geological Society (London), p. 45–59.</ref>) and numerous papers have dealt with various other aspects of the graben (see Connell, 2018<ref name=Connell2018>Connell, E. R., 2018, [http://archives.datapages.com/data/specpubs/memoir115/data/619_aapg-sp2050619.htm Bibliography of geological publications and Ph.D. theses from the South Viking Graben area, North Sea], in C. C. Turner, and B. T. Cronin, eds., Rift-related coarse-grained submarine fan reservoirs; the Brae Play, South Viking Graben, North Sea: [http://store.aapg.org/detail.aspx?id=1301 AAPG Memoir 115], p. 619–628.</ref>, for a full reference list). However, more accurate depictions of the [[structure]], particularly the western fault-bounded [[margin]] and the internal [[structure]] of the graben fill, are now possible due to the complete coverage of the area by high-quality 3-D [[seismic data]]. A 3-D image of the south and central parts of the Viking Graben and its flanks, at Base [[Cretaceous]] level, is shown in [[:file:M115CH02FG02.jpg|Figure 2]]. In addition, extensive released well-data sets are available in this mature hydrocarbon province that allow comprehensive analysis of the [[stratigraphy]] and a clearer understanding of the extent of [[submarine fan]]s containing [[hydrocarbon reservoir]]s.

The South Viking Graben (SVG), in the northern part of the [[North Sea]], is a well-studied Middle to Upper [[Jurassic]] [[rift basin]] containing a major [[hydrocarbon province]] that extends across the border between the [[United Kingdom]] and [[Norway]]. Thermal doming during the [[Toarcian]]–[[Aalenian]], centered on the area south of the southern end of the SVG, resulted in the deposition of thick Middle Jurassic sequences along a north-trending basin that is now the SVG (Underhill and Partington, 1993<ref name=Underhillandpartington1993>Underhill, J. R., and M. A. Partington, 1993, Jurassic thermal doming and deflation in the North Sea: Implications of the sequence stratigraphic evidence, in J. R. Parker, ed., Petroleum Geology of Northwest Europe: Proceedings of the 4th Conference: Geological Society (London) Conference Series 4, p. 337–345.</ref>; and see Hoth et al., 2018<ref name=Hothetal201>Hoth, S., D. Knaust, A. Sánchez-López, S. Kassold, and S. Sviland-Østre, 2018, [http://archives.datapages.com/data/specpubs/memoir115/data/387_aapg-sp2050387.htm The Gudrun field: Gravity-flow deposition during rifting and inversion]], in C. C. Turner, and B. T. Cronin, eds., Rift-related coarse-grained submarine fan reservoirs; the Brae Play, South Viking Graben, North Sea: [http://store.aapg.org/detail.aspx?id=1301 AAPG Memoir 115], p. 387–422.</ref>). Subsequent deflation of the dome was followed by significant [[rift]]ing in the SVG, which began in the [[Callovian]]. However, the most active phases of rifting occurred during the [[Oxfordian]] to early [[Volgian]] (early [[Tithonian]]), when very thick [[synrift]] sequences were deposited in the graben. The graben is bounded on the west by the Fladen Ground Spur (FGS) and on the east by the Utsira High ([[:file:M115CH02FG01.jpg|Figure 1]]). A large proportion of the [[hydrocarbon]] reserves is found in synrift to early [[postrift]], deep-marine [[clastic]] [[sediment]]s of the [[Brae Formation]]; these accumulations are informally termed the [[Thelma field#Brae Play|Brae Play]]. The Brae Formation [[interfinger]]s with, and is overlain by, the [[Kimmeridge Clay Formation]] (KCF; termed [[Draupne Formation]] in Norway). The KCF-Draupne Formation is the major [[source rock]] and is the most significant [[seal]] for trapped Brae Play hydrocarbons. Several previous publications have shown the outlines and general internal structure of this buried half-graben (e.g., Harris and Fowler, 1987<ref name=Harrisandfowler1987>Harris, J. P., and R. M. Fowler, 1987, Enhanced prospectivity of the Mid-Late Jurassic sediments of the South Viking Graben, northern North Sea, in J. Brooks and K. Glennie, eds., Petroleum Geology of North West Europe: Bath, U.K., Graham and Trotman, p. 879–898.</ref>; Johnson et al., 1993<ref name=Johnsonetal1993>Johnson, H., P. C. Richards, D. Long, and C. C. Graham, 1993, United Kingdom offshore regional report; the geology of the northern North Sea: London, HMSO, for the British Geological Survey.</ref>; Sneider et al., 1995<ref name=Sneideretal1995>Sneider, J. S., P. de Clarens, and P. R. Vail, 1995, Sequence stratigraphy of the Middle to Upper Jurassic, Viking Graben, North Sea, in R. J. Steel, V. L. Felt, E. P. Johannessen, and C. Mathieu, eds., Sequence stratigraphy on the Northwest European margin: Norwegian Petroleum Society Special Publication 5, p. 167–197.</ref>; Thomas and Coward, 1996<ref name=Thomasandcoward1996>Thomas, D. W., and M. P. Coward, 1996, Mesozoic regional tectonics and South Viking Graben formation: Evidence for localized thin-skinned detachments during rift development and inversion: Marine and Petroleum Geology, v. 13, p. 149–177.</ref>; Fraser et al., 2003<ref name=Fraseretal2003 />; Zanella and Coward, 2003<ref name=Zanellaandcoward2003>Zanella, E., and M. P. Coward, 2003, Structural framework, in D. Evans, C. Graham, A. Armour, and P. Bathurst, eds., The Millennium Atlas: Petroleum geology of the central and northern North Sea: Geological Society (London), p. 45–59.</ref>) and numerous papers have dealt with various other aspects of the graben (see Connell, 2018<ref name=Connell2018>Connell, E. R., 2018, [http://archives.datapages.com/data/specpubs/memoir115/data/619_aapg-sp2050619.htm Bibliography of geological publications and Ph.D. theses from the South Viking Graben area, North Sea], in C. C. Turner, and B. T. Cronin, eds., Rift-related coarse-grained submarine fan reservoirs; the Brae Play, South Viking Graben, North Sea: [http://store.aapg.org/detail.aspx?id=1301 AAPG Memoir 115], p. 619–628.</ref>, for a full reference list). However, more accurate depictions of the [[structure]], particularly the western fault-bounded [[margin]] and the internal [[structure]] of the graben fill, are now possible due to the complete coverage of the area by high-quality 3-D [[seismic data]]. A 3-D image of the south and central parts of the Viking Graben and its flanks, at Base [[Cretaceous]] level, is shown in [[:file:M115CH02FG02.jpg|Figure 2]]. In addition, extensive released well-data sets are available in this mature hydrocarbon province that allow comprehensive analysis of the [[stratigraphy]] and a clearer understanding of the extent of [[submarine fan]]s containing [[hydrocarbon reservoir]]s.

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