The type and distribution of lithofacies, borne of primary sedimentological processes, has a direct control on the physical properties of sediment bodies, and it is therefore unsurprising that facies distributions exert some control on the development and distribution of small-scale structures.
The relationships between deformation bands and larger scale faults have been well documented (Fossen et al., 2007; Kolyukhin et al., 2010), as have relationships to bulk lithology (Pittman, 1981), but little attention has been given to controls on deformation band formation by depositional processes and facies directly. Preliminary field observations, by the present authors indicate that structural deformation bands occur preferentially within clean, aeolian sandstones, and less so in more immature (but good reservoir) fluvial facies subject to the same regional and local stresses. However, the structures and exact geometries that these deformation bands inhabit, and their relationships to lithofacies, are poorly understood.
This is important to reservoir characterisation as deformation bands can be barriers to flow by generating zones of reduced permeability, especially in mature fields where the in-reservoir reduced pressure gradients exacerbate the deformation bands’ effectiveness as baffles (Fossen and Bale, 2007).
Despite the negative connotations to reservoir quality, the types and distributions of deformation bands have never been studied with regard to a primary sedimentological facies control. As such, this project will undertake a detailed field campaign using the well-exposed, mixed aeolian-fluvial Sherwood Sandstone Group of the Cheshire Basin as a principal case study.
The Sherwood Sandstone in this area contains a full range of aeolian and fluvial facies types and, crucially, is well exposed in a range of outcrops that allow a three-dimensional insight. Data collection will be used to create a detailed sedimentological framework that will establish the geometries and distribution of both aeolian and fluvial facies types. This framework will be used to construct models that detail i) the occurrences, geometries and connectedness of deformation bands, and, ii) porosity and permeability data of both deformation bands and lithofacies (using a field permeameter and lab analysis).
Such an approach will develop generic models of possible lithofacies control(s) on deformation bands, and deformation styles. Additionally, the collection of poro-perm data will be used to identify potential impacts to reservoir quality in three-dimensions resulting from a range of deformation geometries and any anisotropy associated with such assemblages. The results from this completed project could therefore be used to better highlight lithofacies types that are more or less susceptible to deformation band formation and as such, address aspects of reservoir management.
CDT Research theme
Extending the life of mature basins
Hydrocarbon exploration is currently under prepared to define the potential risks associated with deformation bands and the reductions in recovery that could result. This project will provide a means of evaluating deformation band geometry, connectedness and permeability in relation to lithofacies within the reservoir.
The Basin Dynamics Research Group has a strong background in the study of both arid continental sedimentary successions and structural controls on fluid migration. This project would align well with past research, and also bring a new dimension to the group’s current expertise. The project will benefit from BGS collaborators that specialise in clastic sedimentology.
Exploration and production geology, carbon capture, sedimentology, structural geologist.
Training & Skills
As part of a CDT cohort, you will receive 20 weeks bespoke, residential training of broad relevance to the oil and gas industry: 10 weeks in Year 1 and 5 weeks each in Years 2 and 3. Instructors will be both from expert academics from across the CDT and also experienced oil and gas industry professionals.
You will be expected to present posters and talks at national and international conferences.
Funding support is provided as follows;
4 years’ funding for tuition fees and stipend.
Stipend at Research council rates (£14,057 per annum).
Research Training Support Grant.
NERC Centre for Doctoral Training (CDT)
Available to UK citizens and to citizens of the EU who have been permanently in residence in the UK for a minimum of 3 years prior to taking up the studentship.
https://www.keele.ac.uk/bdrg/nerccdtoilgas/ - This project is one of four being offered for September 2016, of which two will be funded.
Qualifications, Experience and Skills Essential: 2:1 or better BSc in Geology/Geoscience subject with good grounding in sedimentology and sequence stratigraphy.
Fieldwork skills and reasonable aptitude with IT and numerical data analysis.
Attitude and personality
The ability to work both independently and as part of a team
Natural inquisitiveness and a flair for problem solving
Ability to plan fieldwork