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The mechanical data (confining and injection pressures) recorded during Vickers indentation experiments on samples of shale materials. These experiments were conducted on the I12 beamline, Diamond Light Source, Harwell as part of beamtime EE17606-1 between 31/01/18 and 05/02/18.
These data accompany a manuscript, titled: Stream and Slope Weathering Effects on Organic-rich Mudstone Geochemistry and Implications for Hydrocarbon Source Rock Assessment: A Bowland Shale Case Study All files with prefix 'Man_1' relate to this submission. The manuscript was submitted to the journal Chemical Geology in December 2016. Data include: 1) A range of photographs from the outcrop, drill cores, sub-samples, 'weathering grades' and thin section microphotographs from the Bowland Shale; 2) The results of mineralogical (whole rock powder x-ray diffraction; XRD) analyses for 18 subsamples; 3) The results of inorganic geochemical analyses (LECO elemental C and S, x-ray fluorescence major and trace elements) for 18 subsamples; 4) The results of organic geochemical analyses (Rock-Eval pyrolysis, d13Corg) for 20 subsamples; 5) RStudio scripts used to conduct statistical analyses (e.g., Principal Components Analysis) and generation of figures.
The data were produced by Joe Emmings, NERC-funded PhD student at the University of Leicester and British Geological Survey, between 2014 and 2017. Authors of these data: Joe Emmings a, b; Sarah Davies a; Christopher Vane b; Melanie Leng b, c; Vicky Moss-Hayes b; Michael Stephenson b a School of Geography, Geology and the Environment, University of Leicester, University Road, Leicester, LE1 7RH, UK. b British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK. c School of Biosciences, Centre for Environmental Geochemistry, University of Nottingham, Sutton Bonington Campus, Leicestershire LE12 5RD, UK. Data include: 1) A range of photographs from the outcrop Hind Clough and boreholes MHD4 and Cominco S9, sample photographs, thin section scans, microphotographs (transmitted light and scanning electron microscopy) and hand specimen descriptions; 2) The results of 100 analyses from the outcrop Hind Clough and boreholes MHD4 and Cominco S9; x-ray fluorescence major and trace element concentrations, RockEval pyrolysis measurements, x-ray diffraction traces and LECO elemental C and S data. These data were interpreted together with 20 drill-core samples previously acquired from Hind Clough ('HC01' prefix). See http://dx.doi.org/10.5285/c39a32b2-1a30-4426-8389-2fae21ec60ad for further information regarding this drill-core dataset. Acknowledgements: This study was funded by NERC grant NE/L002493/1, a part of the Central England Training Alliance (CENTA). This study also received CASE funding from the BGS. Nick Riley (Carboniferous Ltd) is thanked for sharing his expertise, particularly regarding the field identification of marine faunas. Charlotte Watts is thanked for providing field assistance. Nick Marsh, Tom Knott and Cheryl Haidon are thanked for providing expertise and assistance during inorganic geochemical and mineralogical analyses.
The mechanical data (loads, displacements) recorded during double torsion experiments on samples of 6 shale materials and a sandstone. These experiments were conducted on the I12 beamline, Diamond Light Source, Harwell as part of beamtimes EE13824-1 and EE13824-2 between 26/02/17 and 03/03/17. The data were collected using the standard double-torsion technique, with a load cell behind the actuator recording applied force. The method and results are described in detail by Chandler et al, (2018,submitted) "Correlative optical and X-ray imaging of strain evolution during Double Torsion Fracture Toughness measurements in shale" The data was collected with the aim of correlating local deformation around a progressing fracture (through X-Ray and optical imaging) with recorded mechanical data from the loading system. The data was collected by M. Chandler, A-L Fauchille, J. Mecklenburgh, H. K. Kim and L. Ma, and was processed by M. Chandler and R. Rizzo. The complete dataset is present.
Image data published in AGU paper "Estimation of Capillary Pressure in Unconventional Reservoirs Using Thermodynamic Analysis of Pore Images". The images of unconventional shale rock pores were captured using nano-CT and SEM imaging methods. Images are segmented into fluid (or pore) and rock phases and are stored in RGB format as JPG files. Images were used to produce the plots and data presented in the above referenced paper.
These maps provide an overview, at the national scale, of the spatial relationships between principal aquifers and some of the major shale and clay units in England and Wales. The data comprises a series of occurrence maps shows the distribution of rock units that form the principal aquifers and some major shale and clay units in England and Wales. In addition, a series of separation maps show the vertical separation between pairs of shales or clays and overlying aquifers. If shale gas resources are to be developed in the UK, the implications for groundwater will need to be considered as part of any risk assessment. A step in such an assessment will be to understand and quantify the spatial relationships between the potential shale gas source rocks (including both shales and some clay units) and overlying aquifers. The datasets used to produce the aquifer maps, the shale and clay occurrence maps and the separation maps are available to download for your own use. As with other BGS data sets available for download, this will enable you to work offline to develop your own systems and methodologies using BGS data. The data used to produce the aquifer, shale and clay maps are available below as ESRI GIS and KML files.
Whole rock and sediment geochemical data covering a range of elements, where values are given in ppm (parts per million) or as a % (percentage). The data is ordered chronologically in an excel spreadsheet and each sample is given a ‘Sample ID’, ‘Lithology’, ‘Locality’, ‘Age’ and ‘Date analysed’, followed by whole rock and sediment values for the following elements; Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Ge, Hf, Hg, In, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Pd, Pt, Rb, Re, S, Sb, Sc, Se, Sn, Sr, Ta, Te, Th, Ti, TI, U, V, W, Y, Zn, Zr. Cells which are highlighted orange signify that the value given was below the detection limit. The values in orange cells have been halved to maintain spreadsheet functionality (i.e. to remove ‘<’ symbols). Cells which have been highlighted blue signify that the value given was above the detection limit. ALS method:ME-MS41L (https://www.alsglobal.com/en/services-and-products/geochemistry/geochemistry-testing-and-analysis/whole-rock-analysis-and-lithogeochemistry) . The majority of the samples included in this data were collected in the UK, but, where appropriate, samples out with the UK were included. The majority of the data was collected from 2014 to 2019. Whole rock and sediment samples were analysed by solution ICP-MS. Samples of ~30 g were individually milled and homogenised, and 0.5 g were digested with aqua regia in a graphite heating block. The residue was diluted with deionised water (18 M¿ cm), mixed, and analysed using a Varian 725 instrument at ALS Minerals (Loughrea; method ID: ME-MS41L). This data was collected to better understand the low temperature cycling of Telurium (Te) and Sellenium (Se) in the geological environment. For example, a range of ochre samples were included in this database. Ochres are a modern precipitate commonly found in rivers and streams which flow through geographical areas with a history of mining resources which are rich in sulphides. Iron from the sulphides are leached out and deposited downstream, coating river and stream beds, giving a red, yellow or orange colouration. Ochres can be a sink for trace metals, so analysing the abundances of these can be informative from a resource perspective but also from an environmental hazard perspective. This would be useful for researchers who require reference data for whole rock and sediment data of a particular lithology or age. This data is was collected by, but not limited to the following individuals; John Parnell, Sam Spinks, Josef Armstrong, Liam A Bullock, Magali Perez, Xueying Wang & Connor Brolly.
A worldwide compilation of 645 analyses of Sm and Nd concentrations, and Nd isotopes, in fine-grained continental sedimentary rocks with a range of deposition ages. These data were used in Dhuime et al. (2017, Sedimentary Geology 357, 16-32) to calculate the variation in the Nd model age of fine-grained continental sediments as a function of their age of deposition.
This dataset contains dissolved methane concentrations from groundwater in Great Britain, predominantly from England. Data were collated in Microsoft Excel (.xlsx) format from four publicly accessible sources: the British Geological Survey (from Bell et al., 2017), the Environment Agency for England (from the online Water Quality Archive), and local baseline data for the shale gas sites of Preston New Road (from Cuadrilla Resources) and Kirby Misperton (from Third Energy). In total, 2997 dissolved methane concentrations are included in the dataset and were collected from 922 unique locations from October 1992 to July 2018. The data were used within a Bayesian framework to create a dynamic baseline (a baseline that can change in time and space to reflect ongoing environmental change) that can predict the probability that a change in dissolved methane concentration has occurred, for example in the context of monitoring aquifers at shale gas sites using hydraulic fracturing methods. The data presented are the underlying dataset to Wilson et al., 2020, Science of the Total Environment: https://doi.org/10.1016/j.scitotenv.2019.134854. Bell, R. A., Darling, W. G., Ward, R. S., Basava-Reddi, L., Halwa, L., Manamsa, K., & Dochartaigh, B. Ó. (2017). A baseline survey of dissolved methane in aquifers of Great Britain. Science of the Total Environment, 601, 1803-1813. Wilson, M. P., Worrall, F., Davies, R. J., & Hart, A. (2020). A dynamic baseline for dissolved methane in English groundwater. Science of The Total Environment, 711, 134854.
A number of processes, both natural and anthropogenic, involve the fracture of rocks subjected to tensile stress, including vein growth and mineralization, and the extraction of hydrocarbons through hydraulic fracturing. In each case, the fundamental material property of mode-I fracture toughness must be overcome in order for a tensile fracture to nucleate and propagate. Whilst measuring this parameter is straightforward at ambient pressure, estimating the fracture toughness of rocks at depth, where they experience a confining pressure, is technically challenging. Here, we report a new analysis combining results from standard thick-walled cylinder burst tests with quantitative acoustic emission to estimate the mode-I fracture toughness (KIc) of Nash Point Shale at elevated confining pressure, simulating in-situ conditions to approximately 1km. In the most favorable orientation, the pressure required to fracture the rock shell (injection pressure, Pinj) increases from 6.1 MPa at 2.2 MPa confining pressure (PC), to 34 MPa at 20 MPa confining pressure. When fractures cross the shale bedding, the required injection pressures are 30.3 MPa (at Pc = 4.5 MPa) and 58 MPa (at Pc = 20 MPa), respectively. Applying the model of Abou-Sayed (1978) to estimate initial flaw size, we calculate that this pressure increase equates to an increase in KIc from 0.6 MPa.m1/2 at 3.2 MPa differential pressure (Pinj - PC) to 4.1 MPa.m1/2 at 22 MPa differential pressure. We conclude that the increasing pressure due to depth in the Earth will have a significant influence on fracture toughness, which is also a function of the inherent anisotropy.