Postgraduate Research Showcase
Indoor Meeting
School of Earth and Environment, University of Leeds
1st March 2025, 13:30 - 17:00
We’ll be meeting at the University of Leeds to hear from a range of postgraduate researchers about their latest findings!
This meeting will be held in the seminar rooms of the School of Earth and Environment, University of Leeds.
Building 84 on the campus map, please entre via the north door (see image to right (c) Uni of Leeds). Pay and display parking is available on the campus. If you are arriving by public transport, details can be found here.
Presentations include:
Analysis of topographic variations in the Lower Cretaceous of the Central North Sea: implications for reservoir distribution
Carys Simpson(1), Adam McArthur(1), David Hodgson(1), Peter Haughton(2), Stuart Archer(3), Laura Armstrong(3), Miquel Poyatos-More4, Aurelia Privat(1).
(1) School of Earth and Environment, University of Leeds (2) School of Earth Sciences, University College Dublin (3) Harbour Energy, Aberdeen (4) Department of Geology, Universitat Autonoma de Barcelona.
Sediment gravity flow interactions with topography may determine sediment dispersal routes, the location of erosion and depositional processes, and control stratal architecture of deep-water turbidite systems, which host major reservoirs. Greater understanding of the evolving interactions of deep-water sedimentary systems with post-rift structures are needed to improve prediction of heterogeneity in reservoirs deposited adjacent to inherited tectonic structures.
To examine post-rift deep-water turbidite systems, 3D seismic reflection data covering approximately 2,800,000 m2 was used to map the Lower Cretaceous interval of the NW area of the Central North Sea, specifically around the Brodgar and Leverett fields. Structure and isopach mapping of the interval indicates that some major structures, such as the Highland Boundary Fault (HBF), may have still been active into the Lower Cretaceous post-rift, contemporaneous with deposition of the Valhall and Sola Formations. The seismic interpretation permitted mapping of the Base Cretaceous Unconformity and Base Chalk reflections to constrain the study interval. The stratigraphic package comprises several key horizons which were mapped with the aim of constraining the Britannia Sandstone Formation between these two surfaces. The lower section, in the Leverett sub-basin, is characterised by thick bedded, amalgamated sandstones. Contrastingly, the contemporaneous deposits accumulated in the Brodgar field correspond to thin heterolithics, implying a fill of topography behind the HBF before flows continued downstream. In the younger Sola formation, amalgamated beds and conglomerates of the Kilda sandstones, interpreted to be channel-fill deposits, imply topographic healing that promotes sediment bypass downstream over the HBF. Furthermore, the turbidite system is capped by mass transport deposits (MTDs), which indicate the shutdown of sand supply and transition toward deposition of the Upper Cretaceous chalks. The MTDs indicate shedding of shallow-marine clasts, these may have come from the degradation of the Renee Ridge or Rattray High, implying they were still active structures at the time of MTD emplacement.
This stratigraphic sequence implies the filling of upstream depocenters and progressive bypass of reservoir sands to other downdip depocenters. Suggesting, even in post-rift settings, relict topography may exert a key control on sediment distribution across subtle inherited rift topography.
The value of data breadth when evaluating secondary aquifers for shallow geothermal energy
Joe Kelly, School of Civil Engineering, Geosolutions Leeds, University of Leeds
The Elland Flags sandstone, which underlies the University of Leeds (UoL) campus and much of the wider region, is designated only as a secondary aquifer and as such, this and numerous aquifers like it are often overlooked in urban energy planning and national decarbonisation strategies. However, they have a potentially important role to play in shallow geothermal development and therefore, how they are cost-effectively characterised is an important challenge for planners.
Initial investigations used historical borehole data, geological maps, and primary data from local exposures to build a conceptual geological model, constraining the aquifer geometry, identifying mapped faults, and understanding the likely nature of fractures. Field observations and samples enabled better constraint of target horizons, structural trends and heterogeneity. The aquifer is highly heterogeneous, with low primary porosity but extensive fracturing, suggesting high permeability in the subsurface.
This initial phase aided planning of an exploratory drilling campaign on the campus. Rock core has shown the reliability of models built from legacy data, and thermal response test (TRT) results indicate high groundwater flow, supporting the presence significant fracture permeability. More advanced techniques, such as geophysical logging, core analysis and fibre optic distributed TRTs offer the opportunity to assess geothermal potential over a wider area, without recourse to expensive coring.
Developing an increasingly granular aquifer model can help to better simulate system operation and sustainably manage the resource in the long term, reducing risks at different project phases. This approach has also allowed evaluation of a range of desk- and field-based ways to develop the best value strategies for assessing future geothermal schemes, and could have important implications for heat provision in urban environments where major aquifers are not accessible, expanding the potential reach of open-loop geothermal systems.
Self-confinement by submarine debris flows: an example from offshore NW Australia
Yan Li, David Hodgson, Jeff Peakall
School of Earth and Environment, University of Leeds
Submarine landslides, especially debris flows, can entrain the substrate and bulk-up in volume considerably. However, the detailed process mechanics and the evolution of such flows are poorly understood. Our study uses 3-dimensional seismic reflection data from offshore northwest Australia to show that submarine debris flows can result in sequential basinward deposition of debrite lobes through self-confinement.
Multiple submarine landslides have been documented offshore NW Australia, and here we focus on a near seabed submarine landslide that is interpreted as a debris flow, and characterized by its elongated shape (60 km long and 10 km wide) and clear headwall evacuation zone. The ratio of deposited to initially evacuated sediment volume is up to 2.9, which suggests most of the landslide volume came from substrate entrainment during emplacement. The basal shear surface gradually cut downward and formed boundaries for debrite lobes. The existence of steep lateral margins shows that the submarine debris flows became self-confined and channelized, and eventually transformed to submarine lobes. Km-long and 100 m-wide grooves are formed on the basal shear surface, and are locally cut by other 100-meter-long grooves on the lateral margins. Their orientation, distribution and cross-cutting relationship indicate the progressive basinward stepping of debrite lobes, and deepening of the basal shear surface such that the oldest grooves are elevated ~60 m above the youngest grooves in the most proximal areas.
The evolving deposition topography provided by the stacking of debrite lobes progressively increases the confinement of the flow, and the entrainment of substrate allows the flow to lengthen farther into the basin. The grooves as spatially associated with megaclasts towards the fringes of debrite lobe, which are interpreted to be derived from the headwall and substrate entrainment during the deepening and lengthening of flow. The flow evolution and basinward propagation are also enhanced by the presence of diapirs with seabed expressions that further restrict the flow pathway to enhance self-confinement. It is important to understand how flows entrain the substrates to improve predictions of geohazard potential.
We’ll also be welcoming back our winner from 2023, Rifky Wijanarko
Subsurface Storage Potential and Aquifer Distribution of the Permian Rotliegend Group in Yorkshire, NE England
Rifky Wijanarko, Prof. John R. Underhill, Dr. Rachel Brackenridge
Deeply buried sedimentary reservoirs are expected to play a key role in decarbonising the UK. Options range from geological CO2 sequestration in depleted fields and saline aquifers to open-loop geothermal energy for space heating. The Permian Rotliegend Group Leman Sandstone Formation (LSF) is a prolific reservoir for many UK gas fields and is the host storage unit for the Viking CCS project in the Southern North Sea.
Using a play-based exploration (PBE) approach, analysis of a variety of subsurface datasets has revealed that the LSF extends onshore but is restricted to the East Midlands Shelf (EMS). Being a benign structure, the EMS is devoid of closures except on its northern margin, where it is crosscut by the Flamborough Head Fault Zone (FHFZ). The Caythorpe depleted gas field comprises an extensional horst block lying in the footwall to and on the southern side of the FHFZ. Its LSF reservoir is also sealed by a thick layer of Upper Permian Zechstein Group evaporites. We suggest that the culmination of a Rotliegend reservoir, thick Zechstein Group caprock overlying it, and a structural trap makes the Caythorpe field a suitable candidate for subsurface storage or geothermal repurposing that could contribute to the UK’s net zero efforts.