PropBase QueryLayer: a single portal to UK physical property databases

Until recently, the delivery of geological information for industry and public was achieved by geological mapping. Now pervasively available computers mean that 3D geological models can deliver realistic representations of the geometric location of geological units, represented as shells or volumes. The next phase of this process is to populate these with physical properties data that describe subsurface heterogeneity and its associated uncertainty. Achieving this requires capture and serving of physical, hydrological and other property information from diverse sources to populate these models. The British Geological Survey (BGS) holds large volumes of subsurface property data, derived both from their own research data collection and also other, often commercially derived data sources. This can be voxelated to incorporate this data into the models to demonstrate property variation within the subsurface geometry. All property data held by BGS has for many years been stored in relational databases to ensure their long-term continuity. However these have, by necessity, complex structures; each database contains positional reference data and model information, and also metadata such as sample identification information and attributes that define the source and processing. Whilst this is critical to assessing these analyses, it also hugely complicates the understanding of variability of the property under assessment and requires multiple queries to study related datasets making extracting physical properties from these databases difficult. Therefore the PropBase Query Layer has been created to allow simplified aggregation and extraction of all related data and its presentation of complex data in simple, mostly denormalized, tables which combine information from multiple databases into a single system. The structure from each relational database is denormalized in a generalised structure, so that each dataset can be viewed together in a common format using a simple interface. Data are re-engineered to facilitate easy loading. The query layer structure comprises tables, procedures, functions, triggers, views and materialised views. The structure contains a main table PRB_DATA which contains all of the data with the following attribution: • a unique identifier • the data source • the unique identifier from the parent database for traceability • the 3D location • the property type • the property value • the units • necessary qualifiers • precision information and an audit trail Data sources, property type and units are constrained by dictionaries, a key component of the structure which defines what properties and inheritance hierarchies are to be coded and also guides the process as to what and how these are extracted from the structure. Data types served by the Query Layer include site investigation derived geotechnical data, hydrogeology datasets, regional geochemistry, geophysical logs as well as lithological and borehole metadata. The size and complexity of the data sets with multiple parent structures requires a technically robust approach to keep the layer synchronised. This is achieved through Oracle procedures written in PL/SQL containing the logic required to carry out the data manipulation (inserts, updates, deletes) to keep the layer synchronised with the underlying databases either as regular scheduled jobs (weekly, monthly etc.) or invoked on demand. The PropBase Query Layer’s implementation has enabled rapid data discovery, visualisation and interpretation of geological data with greater ease, simplifying the parameterisation of 3D model volumes and facilitating the study of intra-unit heterogeneity

Orientation of drill core by use of borehole geophysical imaging

Borehole core must be orientated relative to a geographic coordinate system if meaningful geological, structural and geotechnical information is to be derived from it. This can be achieved by matching core features with features revealed by geophysical images of the borehole wall. The orientation of a reference line marked on the drill core can thereby be calculated, along with the dip and azimuth of any significant features found in the core. A technique developed by the British Geological Survey (BGS) on the basis of borehole imaging is described here and evaluated in the light of results obtained in the orientation of core extracted on behalf of United Kingdom Nirex, Ltd (Nirex)

In-situ stress orientations in the UK Southern North Sea: regional trends, deviations and detachment of the post-Zechstein stress field

The orientation of the maximum horizontal compressive stress (SHmax) in the UK Southern North Sea has been determined using data derived from borehole breakout analysis of four-arm caliper logs. The results agree with existing stress models for NW Europe, confirming that horizontal stresses in the region have an approximately NW–SE orientation of SHmax. This is interpreted as being a result of plate boundary convergence. Local deviations in the SHmax orientations are observed spatially and also vertically within some wells. Some of these deviations are attributed to rotations of the stress field adjacent to faults or between different fault blocks. The data also suggest detachment of the stress regime in the post-Permian cover rocks, caused by the presence of a thick underlying Permian-aged evaporite sequence and associated halokinesis. Analyses of borehole resistivity image logs have been used to verify the SHmax orientations in some wells. These image logs validate some of the stress indicators whilst highlighting a number of deficiencies in the use of four-arm caliper data to characterise borehole breakouts. From the available data it is difficult to unambiguously define the nature of variations from the mean SHmax orientations observed. Further analyses of image log data over greater depth-ranges are therefore required in order to investigate more fully the effects of stress rotations near faults and apparent stress detachment above salt-cored anticlinal structures

State of stress across UK regions

Knowledge of the in- situ stress field is a key constraint for a variety of sub surface activities and crucial for the safe and sustainable use of the sub surface. However is a lack of available stress magnitude data across the UK. This report assesses legacy stress magnitude data along with new analysis to characterise the UK onshore stress field. To investigate the UK onshore in-situ stress field, three regions were studied. The regions were selected based on the potential availability of information to characterise the stress field and their resource potential for unconventional shale resources, highlighted by Andrews et al. (2013). The study focused on: East Yorkshire and North Nottinghamshire, Cheshire and Lancashire and the Weald. The vertical stress across the UK varies between 23 and 26 MPakm-1 with higher values recorded in Cheshire and Scotland compared to East Yorkshire, North Nottinghamshire and the Weald. Pore pressure measurements from Cheshire, Lancashire, East Yorkshire and North Nottinghamshire are hydrostatic with a gradient of 10.19 MPakm-1. Leak off test and formation integrity test data has been used to estimate the gradient of minimum horizontal stress in Cheshire, Lancashire East Yorkshire and North Nottinghamshire. This estimates show that the minimum horizontal stress gradient is two MPakm-1 higher in Cheshire and Lancashire than East Yorkshire and North Nottinghamshire, which is similar to the differences in vertical stress gradients. Legacy maximum horizontal stress data has been compiled from a variety of techniques from the Coal Authority and peer review publications. This data shows that the maximum horizontal stress > vertical stress, When combined with the leak off test and formation integrity test data (which shows vertical stress > minimum horizontal stress) this indicates that the UK is predominately a strike slip faulting environment. Above 1200 m there are indications of reverse faulting though these are largely confined to igneous rocks in Cornwall, Leicestershire and Cumbria. The available information shows that there are similarities in the stress field across the UK though due to the geographic and stratigraphic constraints on the data more information would help to better characterise the stress field

The comparison of core and geophysical log measurements obtained in the Nirex investigation of the Sellafield region

The Sellafield region, west Cumbria, is the focus of one of the most thorough geological investigations in the United Kingdom. The Sellafield Site is defined as an area immediately around the potential repository, extending 6.5 km north-south by 8 km eastwest. Twenty six deep boreholes were drilled within the area up to the end of 1995, with a total depth of approximately 28 km. Most of these boreholes have been continuously cored, a total of over 17 kilometres of core, with average core recovery well in excess of 90%. All boreholes were logged with a comprehensive suite of geophysical logs, including many state of the art tools. Laboratory physical property analysis of hundreds of sample cores has been carried out. Pilot studies were carried out to compare and contrast datasets and to investigate the relationships between the different data scales. Various techniques, including fractal analysis and Artificial Neural Networks, were tried in order to explore the relationships of these data at a variety of measurement scales. The pilot study was conducted in two stages: (1) evaluation of the primary controlling factors of the physical properties; (2) testing the validity of ‘Up-scaling’. The rocks of the Borrowdale Volcanic Group provided the most challenging problems due to the physical properties being dominated by fracturing and associated alteration zones. Relationships between data types at different scales were established suggesting that the extrapolation of properties derived from core and wireline logs across three-dimensional seismic grids would allow an understanding of the properties throughout a three-dimensional volum

The development of linked databases and environmental modelling systems for decision-making in London

A basic requirement for a city's growth is the availability of land, raw material and water. For continued and sustainable development of today’s cities we must be able to meet these basic requirements whilst being mindful of the environment and its relationship with anthropogenic activity. The heterogeneous and complex nature of urban systems where there are obvious environmental and anthropogenic inter-dependencies necessitates a more holistic approach to decision-making. New developments such as linked databases of environmental data and integrated environmental modelling systems provide new ways of organising cross-disciplinary information and a means to apply this to explain, explore and predict the urban systems response to environmental change. In this paper we show how, accessibility to linked databases, detailed understanding of the geology and integrated environmental modelling solutions has the potential to provide decision-makers and policy developers with the science based information needed to understand and address these challenges

Electron temperature fluctuations in NGC 346

The existence and origin of large spatial temperature fluctuations in HII regions and planetary nebulae are assumed to explain the differences between the heavy element abundances inferred from collisionally excited and recombination lines, although this interpretation remains significantly controversial. We investigate the spatial variation in electron temperature inside NGC 346, the brightest HII region in the Small Magellanic Cloud. Long slit spectrophotometric data of high signal-to-noise were employed to derive the electron temperature from measurements derived from localized observations of the [OIII]($\lambda4959 + \lambda5007)/\lambda4363$ ratio in three directions across the nebula. The electron temperature was estimated in 179 areas of 5$^{\prime\prime}\times1.5^{\prime\prime}$ of size distributed along three different declinations. A largely homogeneous temperature distribution was found with a mean temperature of 12 269 K and a dispersion of 6.1%. After correcting for pure measurements errors, a temperature fluctuation on the plane of the sky of $t^2_{\rm s} = 0.0021$ (corresponding to a dispersion of 4.5%) was obtained, which indicates a 3D temperature fluctuation parameter of $t^2 \approx 0.008$. A large scale gradient in temperature of the order of $-5.7\pm1.3$ K arcsec$^{-1}$ was found. The magnitude of the temperature fluctuations observed agrees with the large scale variations in temperature predicted by standard photoionization models, but is too small to explain the abundance discrepancy problem. However, the possible existence of small spatial scale temperature variations is not excluded.Comment: 6 pages, 5 figures, 2 table

The application of componentised modelling techniques to catastrophe model generation

In this paper we show that integrated environmental modelling (IEM) techniques can be used to generate a catastrophe model for groundwater flooding. Catastrophe models are probabilistic models based upon sets of events representing the hazard and weights their likelihood with the impact of such an event happening which is then used to estimate future financial losses. These probabilistic loss estimates often underpin re-insurance transactions. Modelled loss estimates can vary significantly, because of the assumptions used within the models. A rudimentary insurance-style catastrophe model for groundwater flooding has been created by linking seven individual components together. Each component is linked to the next using an open modelling framework (i.e. an implementation of OpenMI). Finally, we discuss how a flexible model integration methodology, such as described in this paper, facilitates a better understanding of the assumptions used within the catastrophe model by enabling the interchange of model components created using different, yet appropriate, assumptions