ORCID Profile
0000-0001-8575-7341
Current Organisation
Friedrich-Alexander-Universität Erlangen-Nürnberg
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Cambridge University Press (CUP)
Date: 30-05-2022
DOI: 10.1017/S0016756822000309
Abstract: Faulted and fractured systems form a critical component of fluid flow, especially within low-permeable reservoirs. Therefore, developing suitable methodologies for acquiring structural data and simulating flow through fractured media is vital to improve efficiency and reduce uncertainties in modelling the subsurface. Outcrop analogues provide excellent areas for the analysis and characterization of fractures within the reservoir rocks where subsurface data are limited. Variation in fracture arrangement, distribution and connectivity can be obtained from 2D fractured cliff sections and pavements. These sections can then be used for efficient discretization and homogenization techniques to obtain reliable predictions on permeability distributions in the geothermal reservoirs. Fracture network anisotropy in the Malm reservoir unit is assessed using detailed structural analysis and numerical homogenization of outcrop analogues from an open pit quarry within the Franconian Basin, Germany. Several events are recorded in the fracture networks from the Late Jurassic the Alpine Orogeny and are observed to be influenced by the Kulmbach Fault nearby with a reverse throw of 800 m. The fractured outcrops are digitized for fluid flow simulations and homogenization to determine the permeability tensors of the networks. The tensors show differences in fluid transport direction where fracture permeability is controlled by orientation compared to a constant value. As a result, it is observed that the orientation of the tensor is influenced by the Kulmbach Fault, and therefore faults within the reservoirs at depth should be considered as important controls on the fracture flow of the geothermal system.
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-11868
Abstract: & & Naturally fractured systems are an important component to fluid flow for a variety of applications, in particular geothermal energy extraction. Geothermal reservoirs often have low rock permeability (e.g. limestone reservoirs) where permeability anisotropy is governed at first order by fractured networks controlled by fracture density, orientation and connectivity. These are often difficult to assess and as such permeability estimates can lead to high uncertainties. Understanding how fracture networks influence permeability of reservoirs is an important aspect to geothermal exploration.& & & & Where subsurface data (e.g. seismic and well) are limited, other data sources for characterising the reservoirs are required. Outcrop analogues are excellent areas for the analysis and characterisation of fractures within the host rocks found at depth. 2D fractured cliff faces and pavements provide information on variation in fracture arrangement, distribution and connectivity which can be utilised in thermohydraulic modelling of the geothermal system.& & & & Through imaging of 2D fractured faces within target reservoir rocks and using efficient discretisation and homogenisation techniques, reliable predictions on permeability distributions in the geothermal reservoirs can be made. Using an ex le from an open pit quarry within the Franconian Basin, Germany, fracture network anisotropy in a geothermal reservoir (Malm) is assessed using detailed structural analysis and numerical homogenisation modelling of outcrop analogues.& & & & Structural analysis shows several events affected the limestone reservoir unit in the area. The first major phase of deformation recorded are steep-angled reverse thrust and strike-slip faulting (stress orientated NNE-SSW) attributed to the Late Cretaceous Inversion. A second deformation phase causing normal faulting and fracturing within a NW-SE stress field is related to the European Cenozoic Rift System (e.g. Eger Rift). The final deformation phase recorded corresponds to the Alpine Orogeny where strike-slip faults and conjugate fractures are formed under a NW-SE compression and NE-SW extension. The faults and fractures are heavily influenced by the Kulmbach Fault, part of the Franconian Lineament Fault System that is observed 10m north of the quarry and active during the multiphase deformation culminating with a reverse throw of 800m.& & & & D imagery is used to capture the fracture networks interpreted through the structural analysis from which different sets of similar fractures are extracted. These are then digitised and meshed for numerical modelling and homogenisation using MOOSE Framework. Three fractured faces are imaged at increasing distance from the Kulmbach Fault to determine the fault impact on the potential flow within the system. The calculated permeability tensors from the homogenisation show differences in fluid transport direction where fracture permeability is controlled by orientation compared to a constant value which would be more pronounced for larger scale simulations. Therefore, for reliable predictions of geothermal flow within the networks, assigning permeabilities for sets is vital. As a result, it is observed that the orientation of the tensor is influenced by the Kulmbach Fault, and thus faults within the reservoirs at depth should be considered as important controls on the fracture flow of the geothermal system.& &
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Ruaridh Smith.