Lead Doc - An integrated assessment of UK Shale resource distribution based on fundamental analyses of shale mechanical & fluid properties.

Lead Research Organisation: Imperial College London
Department Name: Earth Science and Engineering

Abstract

Shale gas has the potential to transform the UK's future energy security. With imports currently accounting for 50% of its domestic gas requirements, projected to rise to roughly 80% by 2035, the big question is 'Are there enough shale gas resources to effectively replace the declining North Sea and Irish Sea gas production, and for how long?' The largest unknown is the potential gas reserves (i.e. recoverable resources) that would be commercially viable to be produced in the UK. There have been a number of differing in-place estimates for the Upper Bowland Shale in the northern England Carboniferous, ranging from 164-447 tcf suggested by Andrews (2013), to 8-19 tcf quoted by Uguna et al. (2017). In the absence of flow test data, reliable recoverable reserves estimates could not have been published. There has been a single well test carried out by Cuadrilla in Lancashire, the results of which have not yet been made public. The industry, the scientific community, the government, and environmental scientists, have been starved of modern borehole electric log, core and well test data with which to assess both resource potential and the associated environmental impact. This is about to change, with drilling planned to take place during the course of the proposed study in Cheshire, Lancashire, North Yorkshire, and North Nottinghamshire.
This research project will focus on the Carboniferous (Bowland Shale) basins of the East Midlands, Lancashire, Cheshire, and Yorkshire. The vision is of a multidisciplinary approach to solving problems in the main research focus areas set out in Challenge 2 of the NERC call. We will bring together key researchers from several institutions around the UK, working on UK shale science from the micro-pore (<10 nm) to the basin scale. Key aspects of shale mineralogy, petrology, geochemistry, stratigraphy, rock mechanics, gas generation and adsorption and fluid flow in low porosity rocks will be combined into a holistic basin-scale model to generate a better scientifically-grounded set of estimates. Key sensitivities related to input parameters will be tested, and more importantly, compared/contrasted with available production data from the planned wells .
The outcome of this 4-year project will be a more scientifically defendable assessment of the location and magnitude of UK shale resources, guided by an improved understanding of the shale properties and fluid flow through the shale, before, during and following hydraulic fracturing to ascertain whether shale gas has the potential to have a marked impact on energy security in the UK for several decades into the future. This project will critically inform the key stakeholders (Government, Industry, Academia, and the general public) of UK shale potential, and will provide input to discussions on future UK energy strategy. Collaboration with those projects funded within the other Challenges in this programme will allow us to assess whether or not this resource can be accessed in a commercially viable and environmentally responsible way.

References
Andrews, I.J. 2013. The Carboniferous Bowland Shale: Geology and resource estimate. British Geological Survey for the Department of Energy and Climate Change, London, UK.
Uguna, C., Snape, C., Vane, C., V. Moss-Hayes, V., Whitelaw, P., Stevens, L., Meredith, W. and Carr, A. 2017. Convergence of shale gas reserve estimates from a high pressure water pyrolysis procedure and gas adsorption measurements. 28th International Meeting on Organic Geochemistry, 17-22 September 2017, Florence, Italy.

Planned Impact

The research carried out in the proposed project will address to fundamental questions related to UK Shale gas. Namely: How much gas and where is it located? Stakeholder interest in accessing new, scientifically calibrated estimates of resources and reserves will be of immense scientific, industry and public interest. Government will also use these outcomes to inform energy policy in the UK for potentially the next 20 years. Regular communication with the other Challenges in this call and industrial partners will take place at a minimum of 6 month intervals. There will also be formal reporting requirements to the funding bodies.

Beneficiaries

Industry
Depending on which current shale gas resource estimates we take (BGS: Andrews 2014) or Urgano (2017) and the recovery factor applied (nominally 10%) the UK would appear to have between 10 and 50 years of potential gas supply from the northern England Carboniferous basins. Assuming UK gas consumption continues at the current rate of approximately 2.7tcf/year. The value of narrowing the range on this estimate cannot be understated. Working with industry partners we can critically test current and evolving academic models of pore and fracture systems in shales against new data acquired by industry. The models will be re-calibrated with real well bore and test data to provide revised models of pore and fracture behaviour. The key to industry and the country is more efficient exploration and exploitation activities. Fewer wells, fewer pads equals less disruption, less emissions and consequently minimised environmental impact.

Government
Having a scientifically supported range of resource estimates for UK shale gas and its location is of immense value to government in terms of framing UK energy policy going forward. CO2 emission commitments require a cleaner energy policy based on gas rather than coal and oil and a resource that is indigenous from either the North and Irish seas and potentially onshore UK. This mitigates emissions related to transportation and the valid criticism that imported gas is just shifting the problem onto someone else.

General Public
One of the key roles we have to play as an informed group is in explaining to the general public from a scientific expert point of view the key pluses and minuses associated with shale gas and the impact of fracking and a potentially large resource might have on industrialisation and environment in the areas we identify that may contain the gas resources.

Publications

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Kettlety T (2020) Stress Transfer From Opening Hydraulic Fractures Controls the Distribution of Induced Seismicity in Journal of Geophysical Research: Solid Earth

 
Description Bowland shale - why it won't work

On visual inspection of cores Bowland shale looks similar to many US shales (e.g. Barnet). However, that is where the similarity ends. The main difference between the prospectivity of UK and US shales is the complex and polyphase tectonic history of the UK and the corresponding structural complexity of the basins in the UK containing organic rich Carboniferous shales. Also, in the US the main shale basins e.g. Barnet and Marcellus are essentially broad foreland basins with laterally continuous shale deposition. In the UK the organic rich Bowland shales are confined to individual fault bounded basins (Fig. 1) and lac k any degree of lateral continuity. To further confuse the matter the shales in the basins are of a different age and young from north to south.

The other areas of differentiation relate to the relatively shallow depths of burial of the shale. This is particularly true of the east Midlands an established conventional oil province where the shale is barely in the gas window in the deeper basinal areas and is largely mature for oil. This is reflected in the dominance of oil over gas in the conventional fields. The basins where the shales have been buried deeper (Bowland due to Permo-Triassic rifting and burial) and the Cleveland (Early Cretaceous rifting and burial) are of consequence located in structurally complex areas. This breaks up the shale layers, makes horizontal drilling on a large-scale problematic and also contributes to poor 3D seismic imaging. The propensity of natural faults and fractures ultimately becomes an issue in these areas during fracking operations.

In terms of the geology the final area we have examined is the geochemistry. The key research here is by our Nottingham University partner group who used hydrous pyrolysis to demonstrate that the Bowland Shale was not capable if delivering economically significant gas resources that would have little impact on the UK energy balance. To quote them directly the estimated reserves in the UK would amount to well below 10 years supply at current consumption (Whitelaw et al 2019).

Note I haven't mentioned the density of population in the key shale areas in the UK. The induced seismicity caused by fracking operations has generated a public concern and lack of support for fracking operations onshore UK which ultimately led to a government-imposed moratorium on fracking operations.
Exploitation Route Government, public and industry. Recent calls for lifting of fracking ban not supported
Providing an understanding of the link between hydraulic fracturing and induced seismicity. This has direct relevance to resource estimation in that without artificial stimulation of the Bowland Shale Formation there are effectively no resources.
Sectors Energy,Environment

URL http://www.ukuh.org/events/annualsciencemeeting1
 
Description Results of observed and modelled impact of induced seismicity during fracking operations used by UK Shale operators Cuadrilla and IGas. Recent assessment of reduced Shale Gas reserves in UK now being communicated to both industry, academic and public communities. Results will be published as a set of 3 peer reviewed papers to be included in a major Geological Society volume later this year.
First Year Of Impact 2000
Sector Energy
Impact Types Societal,Economic