Risk reduction

Geoscience not only helps to decrease the environmental impacts, but also assists in reducing business risks.

Risk reduction

All energy production brings with it associated risks, with both commercial and environmental implications. Geosciences can provide the detailed analysis, modelling and monitoring to mitigate the risks that relate to the subsurface. Work at Leeds is helping to reduce the risks around, for example, the siting of offshore windfarms, disposal of nuclear waste and reservoir sustainability.

Wind Power

Wind power generation is the fastest growing source of energy in the world today, with an increasing focus on offshore wind. Offshore wind turbines and power export cables must be cost effective to deploy, and perform with minimal maintenance. Our researchers use expertise in characterising subsurface sedimentary architecture to better forecast ground conditions, helping to reduce risk and costs through improved siting of turbines. Our expertise in monitoring and modelling of sediment mobility can help to improve the lifespan of windfarm arrays, and reduce maintenance and drive energy efficiency.

Our research is also looking at the potential risks to offshore wind from climate change, such as sea-level rise and extreme weather. We are also helping to identify potential long-term environmental impacts of offshore wind infrastructure, due to changes in sediment dispersal.

Resource sustainability

The potential of reservoirs for geothermal or hydrocarbon extraction or for storage of CO2 can prove to be lower than estimated during feasibility screening. This is usually due to physical and chemical processes that take place over time, or problems such as well scaling or localised damage to the formation. The flow of fluids can be reduced when filter screens or pores become clogged by precipitation of minerals, corrosion-particles or biofilm, by injection of very fine particles or pollution from drilling mud. There are a number of options open to the reservoir operators to tackle these problems, including:

  • hydraulic, chemical or thermal stimulations
  • changing the surface filtering system
  • sealing of clay layers to avoid new inflow of suspensions
  • use of inhibitors to reduce mineral precipitation
  • regular relocation of injection wells or reverse fluid circulation (for compartmentalized reservoirs)

Understanding the properties of the reservoir are essential in choosing a correct treatment program. Decades of working with the oil and gas industry ensures our researchers can support the identification and optimisation of reservoirs used for geothermal energy and hydrocarbon extraction, and CO2 injection. The long-term sustainability of a reservoir can be predicted by early evaluation of its properties and potential reactions between the reservoir rock and injected brine/CO2, as well as flow simulations through time. Leeds’s expertise can assist throughout all stages of a reservoir’s life – from upstream resource development to downstream plant construction and maintenance.

Environmental impact

Geoscience plays a central role in evaluating long-term geological disposal facilities (GDFs) for nuclear waste and in modelling the near-field response of the surrounding host rock of a GDF. Researchers at Leeds have been working with decommissioning authorities in the UK and Europe to help manage their legacy nuclear wastes and identify suitable sites for GDFs.

The engineered containers in which the waste is stored and the natural barriers of the stable geological formation around the GDF means the likelihood of radionuclides migrating into the wider environment is very low. We carry out detailed studies of past and current geological processes to understand likely future changes within and around any underground repository, to enable any risks to be identified and mitigated. The degree of seismic activity has to be assessed through time, as well as effects of glaciation, uplift, erosion and the potential impact of sea-level rise caused by climate change.

We also assess radionuclide movement over time, through collection of samples, measurement of concentrations of radioactivity, radionuclides, chemicals, and other physical properties of the surrounding host rock and the nuclear waste barrier during all phases of facility operation. Our experience in tracking contamination through the subsurface has led to work with Sellafield nuclear decommissioning site, where legacy wastes from the UK’s nuclear power and fuel reprocessing industry are stored.

Monitoring

There is an increasing use of satellite data and numerical models to assess the environmental constraints and energy potential in the renewable energy sector, including solar, wind, hydropower and biomass. Climatology data is also being used to predict energy demand. Research in Leeds focuses on improving the theory and practice of geophysical techniques, such as seismology, numerical modelling, geophysical surveying and geodesy, for tackling subsurface energy, engineering and environmental problems. Current research projects in Leeds in this area include:

  • Application of seismic techniques to mineral exploration.
  • Geophysical techniques to quantify physical properties of cryosphere.
  • Integrated seismic and hydro-mechanical modelling.
  • Modelling and monitoring geological storage of CO2 (Carbon Capture and Storage) and nuclear waste storage.
  • Seismic attenuation of reflected wave amplitudes and their variation with angle of incidence.
  • Gravity and magnetics.

Our researchers use the latest synthetic aperture radar (SAR) satellites and interferometric SAR (InSAR) to monitor ground movements from all causes in the UK and around the world. We work closely with industry, including with University spin-off companies GETECH and SatSense.

Impact case studies

Geoscientists from the University of Leeds are using expertise in seismic data interpretation and stratigraphy to reduce costs and to improve the lifespan of turbines for the offshore wind industry.
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Expertise at the University of Leeds is helping to de-risk exploitation of one of the main onshore sites with potential for UK deep geothermal: the Cheshire Basin.
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Among the most promising, but least understood geothermal systems are those contained within carbonate rocks – namely limestones and dolostones. The way these rocks deform can fundamentally determine the viability of these geothermal reservoirs.
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The depleted North Sea oil and gas fields are commonly put forward as the best sites in the UK for carbon capture and storage (CCS). Another – often overlooked – option is the layer of Triassic sandstone, saturated with salt water, that sits above layers of salt under the North Sea.
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When contaminants leak out from waste disposal sites or industrial processes, it’s vital to know how far and how fast they will spread. This requires understanding of the materials themselves, but also of the subsurface geology and the chemical conditions through which they will travel.
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Several years ago, Sweden’s national nuclear energy company, SKB, identified a suitable site for the country’s repository for spent nuclear waste fuel at Forsmark, 200 km north of Stockholm.
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Recent research projects

Mobile North Sea seabed for the offshore wind farms

Using new high-resolution seismic reflection data, generated by offshore surveys, the project studies the sedimentary environments preserved below the seabed of the North Sea. The research analyses how the submerged landscapes of the North Sea evolved over the past 500,000 years, allowing us to build detailed maps of former land surfaces and understand the complex depositional environments and the structure of the sediments. This gives wind farm companies the valuable insights needed for positioning new turbines securely on the variable sediments and mobile sea floor. Lead researcher: Prof Dave Hodgson, the Stratigraphy Group.

Carbonate reservoir characterisation

The key aim of Carbonate Fault Rock Group is to create a step change in modelling the impact of faults on fluid flow in carbonate rocks. This has been achieved through a combined approach of new experimental work, data mining and integration of petrophysical and mechanical property analysis with microstructural analysis of fault rocks obtained from outcrop and core to identify the key geomechanical controls on fault rock properties, as well as their impact on fluid flow. The research helps predict reservoir performance in faulted carbonate rocks for geothermal, hydrocarbon and CCS applications. Lead researcher: Prof Quentin Fisher.

Characterisation of low permeability sandstone reservoirs

A key aim of Petrophysics of Tight Gas Sandstone Reservoirs (PETGAS) is to consolidate existing petrophysical data supplemented by new standard and special core analysis to create an atlas of the petrophysical properties of tight sandstones. This provides new insight into the controls of the petrophysical properties (e.g., diagenesis, grain-size, stress etc.), and stress dependency of permeability and relative permeability of tight sandstones. The research helps characterise tight sandstone reservoirs for gas, geothermal and CCS applications. Lead researcher: Prof Quentin Fisher.

Geological characterisation of fluvial and aeolian sediments

The principal aim of the The Fluvial and Eolian Research Group is to conduct cutting-edge research into the application of fluvial and aeolian sedimentology for developing a better understanding of issues relating to environmental geology, hydrocarbon systems, mining and mineral exploration, appraisal of groundwater aquifers and carbon sequestration. This applied-facing research group seeks to devise new methodologies in subsurface geological characterization. The group operates as a Joint Industry Project. Lead researcher: Prof Nigel Mountney.

Geological characterisation of shallow marine sediments

The Shallow Marine Research Group focuses on cutting-edge applied shallow marine research, with emphasis on characterisation of subsurface sedimentary architecture to provide a better understanding of issues related to environmental geology, hydrocarbon systems, mining and mineral exploration, appraisal of groundwater aquifers and carbon sequestration. The research programme covers the following sedimentary environments and reservoir types: deltas, estuaries, paralic wave- and tide-dominated shorelines and clastic shelves. Lead researcher: Prof David Hodgson, Prof Nigel Mountney.

Characterisation of flow regimes for shallow geothermal heat

This project focuses on understanding the flow zonation and the seasonal major ion geochemistry of the Northern Chalk Aquifer. The flow zonation is studied with open-well dilution testing, whereas the geochemistry is studied with loggers in springs and spring water sampling. Knowledge of ambient well flow velocities and flow patterns allow vertical hydraulic characterisation of depth intervals in wells, which are required for effective planning of future geochemical sampling, contaminant tracking, remediation activity, pumping test campaigns and shallow geothermal heat pump installation. Lead researcher: Dr Jared West, Rock Mechanics, Engineering Geology and Hydrology Group.

Stability analysis of shafts used for minewater heat recovery

Traditional heating using non-renewable energy resources contributes up to 50% of current carbon emission level. The water in abandoned mines provides an alternative source of thermal energy that can be extracted through newly drilled boreholes or existing mineshafts. Heat recovery through this mechanism may affect the structural stability of the mineshafts, therefore this project aims to ensure successful and sustainable operation through numerical sensitivity analyses on: (a) water level, (b) temperature fluctuations. Lead researcher: Dr Chrysothemis Paraskevopoulou, Rock Mechanics, Engineering Geology and Hydrology Group

The evolution of natural geothermal systems

The magmatic-hydrothermal systems that form the economically-viable gold deposits are complex, and there remain significant gaps in understanding of how these systems evolve, particularly in the periods of, and between, ore genesis. This study aims to elucidate the physico-chemical conditions of the hydrothermal fluids that facilitate ore deposition in certain parts of an evolving magmatic-hydrothermal system. Understanding the evolution of such natural geothermal systems is crucial in predicting the sustainability of geothermal reservoirs. Lead researcher: Dr Dan Morgan, Ores and Mineralisation Group.

Mechanisms of contaminant migration from buried concrete structures

The focus of this project are the mechanisms of alkaline plume generation at near-surface conditions from inactive and potentially radioactive concrete structures and cementitious rubble and soil from UK nuclear sites. The interaction of this high pH leachate with adjacent soils and the mechanisms of alkalinity attenuation (e.g., carbonation, mineral dissolution) are investigated, in addition to the effects of the imposed pH conditions on the leaching and mobility of contaminant metals and radionuclides present. Lead researcher: Dr Ian Burke, Cohen Geochemistry Group.

Coupling InSAR and geomechanical modelling to monitor spatial and temporal characteristics of CO2 injection

For on-shore carbon sequestration, there has been a significant drive to integrate satellite interferometric synthetic aperture radar (InSAR) with geomechanical modelling to link surface deformation with the movement and storage of injected CO2. The project analyses the surface deformation resulting from CO2 storage at InSalah site, Algeria, in order to provide constraints on the temporal and spatial evolution of CO2 within the reservoir. This study provides the first practical assessment of CO2 storage and demonstrates that it is possible to develop independent, fast and cost-effective assessments of future schemes in the absence of ground-based surveys. The ability to scrutinize CCS sites globally based on limited input data and cost effectively is crucial for implementation of international monitoring of CO2 sequestration agreements. Lead researcher: Prof Andrew Shepherd.

A Sustainable Circular Economy for Offshore Wind

This EPSRC knowledge transfer project is a collaboration between the University of Leeds, the Offshore Renewable Energy Catapult and the Department for International Trade. The project aims to start to integrate circular economy into offshore wind infrastructure design, operation and end-of-use management. A series of outputs will be delivered such as industry and government events, policy and practice briefings, and a framework for circular economy in offshore wind and baseline of current “circular” practices. It also supports knowledge exchange across low-carbon energy and oil & gas and offshore wind sectors, and prepares the ground for a 5-year joint industry partnership on circular economy and wind systems.  Lead researcher: Dr Anne Velenturf.