Mapping the maturity of organic-rich shale with combined geochemical and geophysical data, Draupne Formation, Norwegian Continental Shelf

Characterization of Upper Jurassic Organic-Rich Caprock Shales in the Norwegian Continental Shelf

“…This study used 72 for 'a', 1.3 g/cm 3 for kerogen density, and 2.6 as matrix density for all the petrophysical analyzed wells. Due to different uncertainties, this empirical equation presented a moderate correlation coefficient [41,51]. However, compared with other methods (i.e., ΔlogR), this relation indicated better TOC estimation.…”

“…Upper and lower units also varied vertically within the same wells and laterally between the wells in NCS. Generally, the highly radioactive blackish upper unit was deposited in restricted marine environments with high organic matter, low circulation, and anoxic conditions when compared to open marine deposition for the lower grey unit [35,41,48]. Elastic properties also greatly varied between these two units, where the upper unit has lower density and velocity than the lower unit, except for a few exceptions (Figure 1b,c).…”

“…The studied areas, i.e., the Barents Sea and the North Sea, share similar depositional and structural setups. Yet, there are substantial differences, mainly in the Cretaceous-Cenozoic burial history and exhumation [35,40,41]. All the provinces in NCS are dominated by NW-SE-oriented rifting, followed by rapid subsidence, siliciclastic deposition, infill, and the draping of rift topography in the Early Cretaceous.…”

“…However, in the Late Cretaceous, regional transgression and deposition of thick carbonate sequence characterized the North Sea, while time-equivalent marine deposits are highly condensed because of uplift, erosion, and non-deposition within the Barents Shelf deposits. Rock properties are affected by Cenozoic uplift and erosion in the entire NCS region; however, the Barents Sea area has experienced multiple episodes and maximum net erosion, estimated to be around 1-1.2 km in the Goliat Field area and approximately 2 km in the Hoop area [35,[41][42][43]. Net uplift in the central North Sea is estimated to be from zero to 0.7 km, while 0 to 1.3 km uplift is assessed in the northern North Sea area [44][45][46].…”

Top seal assessment of Drake Formation shales for CO2 storage in the Horda Platform area, offshore Norway

“…Therefore, it is crucial to characterize shale brittleness property to evaluate caprock integrity. However, the brittleness property, which is also classified as fracability (Holt et al, 2015(Holt et al, , 2011Jin et al, 2014;Rybacki et al, 2016;Wang and Gale, 2009;Yang et al, 2013), is a complex function of rock strength, lithology, texture, effective stress, temperature, fluid type (Handin et al, 1963;Handin and Hager, 1957;Nygård et al, 2006), diagenesis, TOC type, amount and maturation (Walles, 2004;Hansen et al, 2020), natural fractures and other planes of weakness (Gale et al, 2007;Zhang et al, 2016;Johnson et al, 2022), etc. There is no firm definition of the brittleness indices; instead, different quantifying methods have been employed (e.g., Fawad and Mondol, 2021;Grieser and Bray, 2007;Guo et al, 2012;Josh et al, 2012;Kivi et al, 2018;Liu et al, 2020;Mondol et al, 2022;Rickman et al, 2008).…”