scholarly journals Evolution of a sand-rich submarine channel-lobe system and impact of mass-transport and transitional flow deposits on reservoir heterogeneity: Magnus Field, northern North Sea

2021 ◽  
pp. petgeo2020-095
Author(s):  
Michael J. Steventon ◽  
Christopher A-L. Jackson ◽  
Howard D. Johnson ◽  
David M. Hodgson ◽  
Sean Kelly ◽  
...  
Keyword(s):  
Mass Transport ◽  
North Sea ◽  
Fluid Pressure ◽  
Transitional Flow ◽  
Rock Properties ◽  
Sweep Efficiency ◽  
Content Type ◽  
Supplementary Material ◽  
Northern North Sea ◽  
The Impact

The geometry, distribution, and rock properties (i.e. porosity and permeability) of turbidite reservoirs, and the processes associated with turbidity current deposition, are relatively well known. However, less attention has been given to the equivalent properties resulting from laminar sediment gravity-flow deposition, with most research limited to cogenetic turbidite-debrites (i.e. transitional flow deposits) or subsurface studies that focus predominantly on seismic-scale mass-transport deposits (MTDs). Thus, we have a limited understanding of the ability of sub-seismic MTDs to act as hydraulic seals and their effect on hydrocarbon production, and/or carbon storage. We investigate the gap between seismically resolvable and sub-seismic MTDs, and transitional flow deposits on long-term reservoir performance in this analysis of a small (<10 km radius submarine fan system), Late Jurassic, sandstone-rich stacked turbidite reservoir (Magnus Field, northern North Sea). We use core, petrophysical logs, pore fluid pressure, quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN), and 3D seismic-reflection datasets to quantify the type and distribution of sedimentary facies and rock properties. Our analysis is supported by a relatively long (c. 37 years) and well-documented production history. We recognise a range of sediment gravity deposits: (i) thick-/thin- bedded, structureless and structured turbidite sandstone, constituting the primary productive reservoir facies (c. porosity = 22%, permeability = 500 mD), (ii) a range of transitional flow deposits, and (iii) heterogeneous mud-rich sandstones interpreted as debrites (c. porosity = <10%, volume of clay = 35%, up to 18 m thick). Results from this study show that over the production timescale of the Magnus Field, debrites act as barriers, compartmentalising the reservoir into two parts (upper and lower reservoir), and transitional flow deposits act as baffles, impacting sweep efficiency during production. Prediction of the rock properties of laminar and transitional flow deposits, and their effect on reservoir distribution, has important implications for: (i) exploration play concepts, particularly in predicting the seal potential of MTDs, (ii) pore pressure prediction within turbidite reservoirs, and (iii) the impact of transitional flow deposits on reservoir quality and sweep efficiency.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5313860

Study on the effect of pore-scale heterogeneity and flow rate during repetitive two-phase fluid flow in microfluidic porous media

2021 ◽  
pp. petgeo2020-062
Author(s):  
Jingtao Zhang ◽  
Haipeng Zhang ◽  
Donghee Lee ◽  
Sangjin Ryu ◽  
Seunghee Kim
Keyword(s):  
Porous Media ◽  
Fluid Flow ◽  
Flow Rate ◽  
Sweep Efficiency ◽  
Residual Saturation ◽  
Flow Rates ◽  
Content Type ◽  
Lower Flow ◽  
Supplementary Material ◽  
Lower Flow Rate

Various energy recovery, storage, conversion, and environmental operations may involve repetitive fluid injection and, thus, cyclic drainage-imbibition processes. We conducted an experimental study for which polydimethylsiloxane (PDMS)-based micromodels were fabricated with three different levels of pore-space heterogeneity (coefficient of variation, where COV = 0, 0.25, and 0.5) to represent consolidated and/or partially consolidated sandstones. A total of ten injection-withdrawal cycles were applied to each micromodel at two different flow rates (0.01 and 0.1 mL/min). The experimental results were analyzed in terms of flow morphology, sweep efficiency, residual saturation, the connection of fluids, and the pressure gradient. The pattern of the invasion and displacement of nonwetting fluid converged more readily in the homogeneous model (COV = 0) as the repetitive drainage-imbibition process continued. The overall sweep efficiency converged between 0.4 and 0.6 at all tested flow rates, regardless of different flow rates and COV in this study. In contrast, the effective sweep efficiency was observed to increase with higher COV at the lower flow rate, while that trend became the opposite at the higher flow rate. Similarly, the residual saturation of the nonwetting fluid was largest at COV = 0 for the lower flow rate, but it was the opposite for the higher flow rate case. However, the Minkowski functionals for the boundary length and connectedness of the nonwetting fluid remained quite constant during repetitive fluid flow. Implications of the study results for porous media-compressed air energy storage (PM-CAES) are discussed as a complementary analysis at the end of this manuscript.Supplementary material: Figures S1 and S2 https://doi.org/10.6084/m9.figshare.c.5276814.Thematic collection: This article is part of the Energy Geoscience Series collection available at: https://www.lyellcollection.org/cc/energy-geoscience-series

Carboniferous records of the Zoophycos group of trace fossils from England, Wales, the Isle of Man and the North Sea

2020 ◽  
Vol 63 (2) ◽  
pp. 135-145
Author(s):  
Duncan McLean ◽  
Matthew Booth ◽  
David J. Bodman ◽  
Finlay D. McLean
Keyword(s):  
North Sea ◽  
Trace Fossils ◽  
Depositional Environments ◽  
Common Component ◽  
Content Type ◽  
Clastic Rocks ◽  
Isle Of Man ◽  
The North ◽  
The North Sea ◽  
Supplementary Material

The Zoophycos group of trace fossils is common in Carboniferous to recent marine strata and sediments, and is a common component of ichnofaunas in the Visean and Namurian stages of England and Wales. A review of new and published records indicates that it is often present in limestones and sandstones of Chadian to Arnsbergian age. Thereafter it is less common, and restricted to clastic rocks. There are no known records within Carboniferous strata above the lowest Westphalian. The form is most common and often abundant in limestones of the Yoredale facies in the upper Visean and lower Namurian stages of northern England, particularly so in northern Northumberland. Where detailed sedimentological data exist, they indicate that the organisms responsible for the Zoophycos group burrowed into unconsolidated carbonate substrate that was deposited under low accumulation rates, often affected by storm wave action and where seawater flow provided a nutrient supply. However, in mixed carbonate–clastic settings, the deep-tier nature of Zoophycos may indicate that the organism lived in overlying shallow-marine, clastic-dominated depositional environments and burrowed down into the carbonate substrate. The same may be true of siliciclastic depositional settings where the presence of Zoophycos in some sandstones may reflect the palaeoenvironment of the overlying, finer-grained transgressive marine (prodelta and distal mouth bar) deposits.Supplementary material: A spreadsheet with details of Carboniferous records of Zoophycos group fossils from England, Wales, the Isle of Man and the North Sea is available at https://doi.org/10.6084/m9.figshare.c.4994636

Ammonite occurrences in North Sea cores: implications for Jurassic Arctic–Mediterranean marine seaway connectivity

2020 ◽  
Vol 56 (2) ◽  
pp. 175-195
Author(s):  
Nicol Morton ◽  
Vasily V. Mitta ◽  
John R. Underhill
Keyword(s):  
North Sea ◽  
The Arctic ◽  
Migration Routes ◽  
Content Type ◽  
Upper Bajocian ◽  
Moray Firth ◽  
Extensional Faulting ◽  
Supplementary Material ◽  
The Uk ◽  
Uplift And Erosion

The paucity of ammonite recovery from North Sea wells has meant that offshore correlations are largely dependent upon microfossil assemblages. While rare, ammonites have been found in a few boreholes during the course of oil exploration activities. The occurrence of ammonites in ten wells in the UK sector of the Viking Graben and the Moray Firth rift arms provides a new basis by which to demonstrate that there was a distinct separation between Arctic and sub-Mediterranean species that lasted from Bajocian to Early Callovian times. Five wells contain ‘Boreal Bathonian' ammonites from the Arctic Realm. Arctocephalites from the Boreal Arcticus Zone (uppermost Bajocian) correlates basinal partly anoxic mudstones in the Beryl Embayment (9/13b) with both bioturbated siltstones in the southern Viking Graben (9/10b), and calcareous mudstones in the East Shetland Basin (211/21). Upper Bajocian Pompeckji Zone Cranocephalites and younger Arcticoceras from Lower to Middle Bathonian Greenlandicus, Ishmae and Cranocephaloide zones are confined to 211/21 demonstrating that the marine transgression began earlier and lasted longer. A Cadoceras from well 3/3-8 dates to the Lower Callovian Koenigi and Calloviense zones during which renewed extensional faulting re-established ammonite migration routes between the Boreal and sub-Mediterranean realms. A Middle Oxfordian (Densiplicatum Zone) Perisphinctes from well 22/5b-8 confirms an episode of northward migration from the sub-Mediterranean into the Boreal Realm. Upper Oxfordian (Regulare to Rosenkantzi zones) Amoeboceras in wells 211/21-1 and 9/13b-19 are close to Upper Bajocian/Lower Bathonian faunas, suggesting an absence of Upper Bathonian to Middle Oxfordian strata as a result of rift-related footwall uplift and erosion. In four wells from Block 15/21 (-4, -11, -12A and -25) Lower Kimmeridgian ammonites have been documented, including Rasenia, Amoebites, Aulacostephanoides and Zenostephanoides, from the Baylei (?), Cymodoce, Mutabilis and Eudoxus zones, the latter (confirmed at well 13/28b-8) dating a widespread regional marine flooding surface in the Inner Moray Firth.Supplementary material: The detailed measurements of dimensions of the ammonites described are available at: https://doi.org/10.6084/m9.figshare.c.5087313

scholarly journals Geomorphic response of a mountain gravel-bed river to an extreme flood in Aberdeenshire, Scotland

2020 ◽  
Vol 56 (2) ◽  
pp. 101-116
Author(s):  
Dina M. Fieman ◽  
Mikaël Attal ◽  
Stephen Addy
Keyword(s):  
Morphological Change ◽  
Early Career ◽  
Difference Threshold ◽  
Lateral Migration ◽  
Content Type ◽  
Link Type ◽  
Extreme Flood ◽  
Supplementary Material ◽  
Career Research ◽  
The Impact

This study uses the 2015 ‘Storm Frank’ flood on the River Dee, Aberdeenshire, to assess the impact of extreme events on river dynamics. The Storm Frank flood (>200 year recurrence interval) caused significant local morphological change that was concentrated in the middle portion of the 140 km long river and overall net degradation that primarily occurred through lateral adjustment processes. Although the flood did not cause widespread change in channel planform, morphological change at the reach scale (<1 km) was significant. Bank scour resulted in channel expansion and lateral migration as well as widespread aggradation on existing gravel beds. The HEC-RAS and CAESAR–Lisflood models were used to determine the impact of morphological changes from the Storm Frank flood on a series of future hypothetical floods. The results show that inundation is highly influenced by the degree of morphological change for moderate floods, but not for high magnitude ones. In-channel scour and bank erosion can lead to an increase in channel capacity, thereby decreasing inundation. Conversely, where conveyance capacity is decreased by aggradation, flood risk inherently increases. The impact of these changes was great for a five-year return period flood, but minimal for a magnitude flood comparable to that of Storm Frank. Our modelling results also reveal that the inundation model is sensitive to the grain size and channel bed roughness input parameters, as these parameters impact flow discharge and flood hydraulics. Accurate determination of sediment parameters and degree of morphological change is therefore critical in flooding modelling and flood hazard management.Supplementary material: Peak discharge and rainfall during the 2015 Storm Frank storm, parameters used in the hydrological model CAESAR–Lisflood and sediment budget statistics of each DEM of difference threshold are available at: https://doi.org/10.6084/m9.figshare.c.4847946Thematic collection: This article is part of the Early Career Research collection available at: https://www.lyellcollection.org/cc/SJG-early-career-research

scholarly journals Multi-Proxy Characterisation of the Storegga Tsunami and Its Impact on the Early Holocene Landscapes of the Southern North Sea

Geosciences ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 270 ◽  
Author(s):  
Vincent Gaffney ◽  
Simon Fitch ◽  
Martin Bates ◽  
Roselyn L. Ware ◽  
Tim Kinnaird ◽  
...  
Keyword(s):  
North Sea ◽  
River System ◽  
Seismic Survey ◽  
Tsunami Deposit ◽  
Southern North Sea ◽  
The North ◽  
Sediment Deposits ◽  
The North Sea ◽  
Northern North Sea ◽  
The Impact

Doggerland was a landmass occupying an area currently covered by the North Sea until marine inundation took place during the mid-Holocene, ultimately separating the British landmass from the rest of Europe. The Storegga Event, which triggered a tsunami reflected in sediment deposits in the northern North Sea, northeast coastlines of the British Isles and across the North Atlantic, was a major event during this transgressive phase. The spatial extent of the Storegga tsunami however remains unconfirmed as, to date, no direct evidence for the event has been recovered from the southern North Sea. We present evidence of a tsunami deposit in the southern North Sea at the head of a palaeo-river system that has been identified using seismic survey. The evidence, based on lithostratigraphy, geochemical signatures, macro and microfossils and sedimentary ancient DNA (sedaDNA), supported by optical stimulated luminescence (OSL) and radiocarbon dating, suggests that these deposits were a result of the tsunami. Seismic identification of this stratum and analysis of adjacent cores showed diminished traces of the tsunami which was largely removed by subsequent erosional processes. Our results confirm previous modelling of the impact of the tsunami within this area of the southern North Sea, and also indicate that these effects were temporary, localized, and mitigated by the dense woodland and topography of the area. We conclude that clear physical remnants of the wave in these areas are likely to be restricted to now buried, palaeo-inland basins and incised river valley systems.

Compaction and rock properties of Mesozoic and Cenozoic mudstones and shales, northern North Sea

2016 ◽  
Vol 76 ◽  
pp. 344-361 ◽  
Author(s):  
Mohammad Koochak Zadeh ◽  
Nazmul Haque Mondol ◽  
Jens Jahren
Keyword(s):  
North Sea ◽  
Rock Properties ◽  
Northern North Sea

Fluid evolution along the Patterson Lake corridor in the southwestern Athabasca Basin: constraints from fluid inclusions and implications for unconformity-related uranium mineralization

2021 ◽  
pp. geochem2020-029
Author(s):  
M. Rabiei ◽  
G. Chi ◽  
E.G. Potter ◽  
V. Tschirhart ◽  
C. MacKay ◽  
...  
Keyword(s):  
Fluid Inclusion ◽  
Fluid Inclusions ◽  
Fluid Pressure ◽  
Uranium Deposits ◽  
Hydrothermal Conditions ◽  
Content Type ◽  
Athabasca Basin ◽  
Link Type ◽  
Basement Faults ◽  
Supplementary Material

The Patterson Lake corridor (PLC) in the southwestern margin of the Athabasca Basin hosts several high-grade uranium deposits. These deposits are located in the basement up to 900 m below the unconformity surface, raising questions about their affiliation with typical unconformity-related uranium (URU) deposits elsewhere in the basin. Based on cross-cutting relationships four pre- and three syn- to post-mineralization quartz generations were identified. Fluid inclusion analyses indicate that pre-mineralization fluids have salinities ranging from 0.2 to 27.2 Wt% NaCl equiv. (avg. 9.0 Wt%), whereas syn-mineralization fluids have salinities ranging from 8.8 to 33.8 Wt% NaCl + CaCl2 (avg. 25.4 Wt%), with NaCl- and CaCl2-rich varieties. The homogenization temperatures (Th) of fluid inclusions from pre-mineralization quartz range from 80 ° to 244 ℃ (avg. 147 ℃), and from syn-mineralization quartz range from 64 ° to 248 ℃ (avg. 128 ℃). Fluid boiling is indicated by the co-development of liquid-dominated and vapor-dominated fluid inclusions within individual fluid inclusion assemblages (FIA) from the syn-mineralization quartz and is related to episodic fluid pressure drops caused by reactivation of basement faults. Our results indicate that composition and P-T conditions of the ore fluids in the PLC are comparable to those of typical URU deposits in the Athabasca Basin, indicating that the uranium deposits in the PLC formed under similar hydrothermal conditions. Episodic reactivation of basement faults was an important driving force to draw uraniferous fluids from the basin and reducing fluids from the basement to the mineralization sites, forming deep basement-hosted deposits.Thematic collection: This article is part of the Uranium Fluid Pathways collection available at: https://www.lyellcollection.org/cc/uranium-fluid-pathwaysSupplementary material:https://doi.org/10.6084/m9.figshare.c.5510179

Advances in conceptualising transport in chalk aquifers

2021 ◽  
pp. SP517-2020-173
Author(s):  
Aidan E. Foley ◽  
Stephen R. H. Worthington
Keyword(s):  
Mass Transport ◽  
Groundwater Flow ◽  
Mapping Method ◽  
Effective Porosity ◽  
Velocity Mapping ◽  
Spatial Scaling ◽  
Groundwater Velocity ◽  
Transport Modelling ◽  
Content Type ◽  
Supplementary Material

AbstractThe conceptualisations of matrix, fracture and fissure porosity are important for understanding relative controls on storage and flow of groundwater, and the transport of solutes (and non-aqueous phase liquids) within chalk aquifers. However, these different types of porosity, rather than being entirely distinct, represent elements in a continuum of void sizes contributing to the total porosity of the aquifer. Here we define such a continuum and critically examine the selection of appropriate values of effective porosity, a widely-used parameter for mass transport modelling in aquifers. Effective porosity is a transient phenomenon, related to the porosity continuum by the timescales under which mass transport occurs. An analysis of 55 tracer tests and 20 well inflow tests in English chalk aquifers identifies spatial scaling in groundwater velocity and groundwater flow respectively, which are interpreted within the context of the wider literature on carbonate aquifers globally. We advance transport modelling in the Chalk by developing a fissure aperture velocity mapping method using transmissivity data from existing regional groundwater models, together with the identified transient and spatial scaling phenomena. The results show that chalk aquifers exhibit widespread rapid groundwater flow which may transport contaminants rapidly in almost any setting.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5403807

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