Research and scholarship
Fault geometry and fault-zone development in mixed carbonate/clastic successions: Implications for reservoir management
Supervisors: Dr Stuart M. Clarke (Keele University), Dr Graham Leslie (British Geological Survey) & David Richardson (Kier Mining)
Funding: Keele University and Basin Dynamics Limited. Fieldwork is supported by the British Geological Survey.
Faults are key controlling elements of fluid flow within reservoirs. When faults undergo displacement, they change their fluid transmissibility by juxtaposing various lithologies across the fault, by developing a fault zone of gouge and by developing a damage zone adjacent to the fault, all of which have the potential to compartmentalise reservoirs and complicate exploitation.
This project will examine fault and fault-zone geometry in mixed clastic, carbonate and coal successions to deliver numerical models of the effects of these on fault-seal potential, reservoir compartmentalisation and reservoir performance.
Quarry exposures of Carboniferous sediments from the Scottish Central Belt
Models for determining juxtaposition relationships are well known (Allan, 1989). Models for predicting the sealing capacity of the fault-zone gouge in siliciclastic successions at seismic scale (Yielding et al., 1997), and in three-dimensional models (Clarke et al., 2005), are now commonplace tools in industry. Similarly, fault development within carbonate successions has been the subject of recent studies, but little attention has been given to mixed carbonate and siliciclastic successions where fault development is complex, and faults may exhibit a strong, staircase geometry, at the sub-seismic, reservoir-interval scale, as they refract through units of differing competency.
Gouge development is highly varied, and extensive damage zones are locally common. Localised, but significant, three-dimensional structures are developed. All of these characteristics are inherently three-dimensional in nature and strongly govern fluid migration, and compartmentalisation within the reservoir. Currently, none of these characteristics is adequately predicted using modelling methods derived from exclusively siliciclastic or carbonate settings.
This project will examine fault development in mine exposures of successions from the Carboniferous Coal Measures Group of the Scottish Central Belt, and natural exposures from Carboniferous outcrop in northern England and Southern Scotland. Within the mines, the project will use new, high-resolution, photogrammetric methods, in conjunction with geophysical techniques, to produce a unique, highly detailed, truly three-dimensional and unparalleled dataset of fault geometry, recorded as the working quarry faces are cut through a number of faults of varied displacement and style.
The dataset will be used to develop three-dimensional models of fault and fault-zone geometry, and fault zone composition, augmented with lithological textures and petrophysical properties gathered from the exposed stratigraphy. The models will be used to examine the effects of faulting, fault geometry and fault-zone development upon fluid migration. The results will be used to determine the parameters that control the sealing capacity of the fault and fault zone, and to develop models to improve understanding of fault seal and reservoir compartmentalisation in mixed carbonate and clastic successions.
- Cain T., Leslie A. G., Clarke S. M., Kelly M. & Krabbendam M. 2014. Finding hidden transverse zones in the Moine Thrust Zone. Talk. Tectonic Studies Group AGM, Edinburgh, United Kingdom.
- Cain T., Clarke S. M. & Leslie A. G. 2015. Investigating Fault Zone Development, Geometries and Properties in Mixed Carbonate and Clastic Successions. Talk. EAGE Fourth International Fault and Top Seals Conference, Almeria, Spain.
- Cain T., Clarke S. M. & Leslie A. G. 2015. Fault Zone Architecture in Coal Bearing Strata. Poster. Tectonic Studies Group AGM, London, United Kingdom.
- Leslie, A.G., Browne, M.A.E., Cain, T. & Ellen R. 2016. From threat to future asset - The legacy of opencast surface-mined coal in Scotland. International Journal of Coal Geology. In press.
- Cain. T., Leslie, A.G., Clarke S.M., Kelly, M. & Kraabendam, M. 2016. Evidence for pre-Caledonian discontinuities in the Achnashellach Culmination, Moine Thrust Zone: the importance of a pre-thrust template in influencing fold and thrust belt development. Journal of Scottish Geology. Accepted for publication