Porosity, permeability and compaction trends for Scandinavian regoliths

Complex Bedrock Fracture Patterns: A Multipronged Approach to Resolve Their Evolution in Space and Time

“…Finally, discoveries of exploitable hydrocarbon reserves in heavily fractured and weathered basement blocks (e.g., Lie et al, 2016;Lothe et al, 2017;Petford & McCaffrey, 2003;Riber et al, 2015) will generate enhanced geophysical imaging of such basement domains. To correctly interpret the geophysical data, however, an integrated understanding of the geological history, especially the brittle deformation history recorded by the individual bedrock domains, remains indispensable.…”

Constraints on upper crustal fluid circulation and seismogenesis from in-situ outcrop quantification of complex fault zone permeability

“…Our results constrain the present-day permeability of the studied fault rocks at the outcrop. Any extrapolation to depth (e.g., at seismogenic depth) would need to consider the effects of increasing confinement and temperature and the presence of hydrothermal fluids (e.g., 37 , 38 ), which generally promote an overall decrease of permeability (e.g., 41 ). Indeed, (i) laboratory permeability tests on different lithotypes (e.g., marble, carbonate and dolostone) and (ii) comparison of downhole and laboratory permeability tests document a general decrease of permeability with increasing confining pressure and/or depth (e.g., 7 , 15 , 42 – 44 ; Fig.…”

In–situ quantification of mechanical and permeability properties on outcrop analogues of offshore fractured and weathered crystalline basement: Examples from the Rolvsnes granodiorite, Bømlo, Norway

“…Specific to this last point, in the recent past, economically viable unconventional oil plays have been defined in structural highs within fractured and weathered crystalline basement blocks (Koning, 2003;Luthi, 2005;Kitchka et al, 2017;Braathen et al, 2018;Bonter and Trice, 2019;Holdsworth et al, 2019Trice et al, 2019;McCaffrey et al, 2020). There, the constituent elements of a reservoir include (Riber et al, 2015(Riber et al, , 2017Fredin et al, 2017b;Braathen et al, 2018;Lothe et al, 2018;Walter et al, 2018;McCaffrey et al, 2020): (1) the host crystalline rock, characterised by primary lowporosity/permeability; (2) fractures, fault zones, mineral veins and open fissures characterised by enhanced micro-and mesoscopic fracture porosity; (3) fluid-rock interaction zones related to either alteration along structural discontinuities or to top-basement paleo-weathering profiles; (4) the buffering/sealing fault zones bounding the structural highs; (5) the sedimentary cover overlying the weathered crystalline basement acting as either reservoir rock, top-seal and/or source rock. The reservoir rock consists of the fractured and altered/weathered crystalline basement, in which fluid storage and transport are dependent mainly on the spatial arrangement, geometry and distribution of 4 "matrix" and "structural" permeability (Braathen et al, 2018;Trice et al, 2019).…”

“…From the Permian onward, the crystalline basement on Bømlo underwent a series of brittle deformation events (Scheiber and Viola, 2018) and experienced pervasive alteration/weathering in response to subaerial exposure in tropical humid climate conditions during the Triassic, forming a thick weathering profile (Fredin et al, 2017b). Similarly, the offshore Utsira High reservoir is characterised by a pervasively fractured crystalline basement, mainly composed of felsic intrusive and gabbroic rocks of Ordovician-Silurian age (Slagstad et al, 2011;Riber et al, 2015), on top of which rests a paleo-weathering profile formed during the late Triassic (Fredin et al, 2017b;Riber et al, 2017;Lothe et al, 2018) (Fig. 2b).…”