Zoe Shipton | University of Strathclyde, Glasgow (original) (raw)

Papers by Zoe Shipton

International Journal of Greenhouse Gas Control, Mar 1, 2021

Nature Energy, Jan 21, 2019

Meeting inter-seasonal fluctuations in electricity production or demand in a system dominated by ... more Meeting inter-seasonal fluctuations in electricity production or demand in a system dominated by renewable energy requires the cheap, reliable and accessible storage of energy on a scale that is currently challenging to achieve. Commercially mature compressed air energy storage (CAES) could be applied to porous rocks in sedimentary basins worldwide where legacy data from hydrocarbon exploration are available, and where geographically close to renewable energy sources. Here we present a modeling approach to predict the potential for CAES in porous rocks. By combining these with an extensive geological database we provide a regional assessment of this potential for the UK.

Scottish Journal of Geology, Jan 12, 2021

AGU Fall Meeting Abstracts, Dec 1, 2011

Abstract Understanding the evolution of fault zone geometrical and hydromechanical properties dur... more Abstract Understanding the evolution of fault zone geometrical and hydromechanical properties during fault growth and network development is of major importance in fluid flow prediction in the crust. In porous rocks, faulting produces zones of deformation bands rather than planar fracture surfaces. Cataclastic deformation bands (CDBs) are mm-cm thick brittle shear zones that form through the combined effects of compaction and cataclasis. Porosity and grain size reduction associated with CDB formation causes strain hardening, and the ...

In June 2008 the UK Government launched the White Paper Managing Radioactive Waste Safely proposi... more In June 2008 the UK Government launched the White Paper Managing Radioactive Waste Safely proposing construction of a deep Geological Disposal Facility. The GDF will be supported by an accompanying safety case that will include providing risk based estimates of the travel times for radionuclides leaving the GDF and travelling through the geosphere. This will require characterisation of the structural geological features surrounding the GDF in terms of location and associated permeability.

$Research paper thumbnail of Mini thief zones: Subcentimeter sedimentary features enhance fracture connectivity in shales$

AAPG Bulletin, Apr 1, 2019

This study examines the influences on fluid flow within a shale outcrop where the networks of two... more This study examines the influences on fluid flow within a shale outcrop where the networks of two distinct palaeo-flow episodes have been recorded by calcite-filled veins and green alteration halos. Such direct visualisation of flow networks is relatively rare and provides valuable information of fluid flow behaviour between core and seismic scale. Detailed field mapping, fracture data, and sedimentary logging were used over a 270m 2 area to characterise the palaeo-fluid flow networks in the shale. Distal remnants of turbidite flow deposits are present within the shale as very thin (1-10mm) fine grained sandstone bands. The shale is cut by a series of conjugate faults and an associated fracture network; all at a scale smaller than seismic detection thresholds. The flow episodes utilised fluid flow networks consisting of subgroups of both the fractures and the thin turbidites. The first fluid flow episode network was mainly comprised of thin turbidites and shear fractures, whereas the network of the second fluid flow episode was primarily small joints (opening mode fractures) connecting the turbidites. The distribution of turbidite thicknesses follows a negative exponential trend; which reflects the distribution of thicker turbidites recorded in previous studies. Fracture density varies on either side of faults, and is highest in an area between closely spaced faults. Better predictions of hydraulic properties of sedimentary-structural networks for resource evaluation can be informed from such outcrop sub-seismic scale characterisation. These relationships between the sub-seismic features could be applied when populating discrete fracture networks models, for example, to investigate such sedimentary-structural flow networks in exploration settings.

Journal of the Geological Society, Nov 22, 2019

The Highland Boundary fault near Stonehaven, NE Scotland, provides a rare opportunity to study th... more The Highland Boundary fault near Stonehaven, NE Scotland, provides a rare opportunity to study the internal fault structure of a well-exposed, along-strike section of an ancient plate boundary fault. As in many plate boundaries, serpentinite juxtaposes quartzo-feldspathic crustal rocks of distinct terranes. We report, for the first time, the complex internal structure of the Highland Boundary fault core, comprised of four structurally and chemically distinct clay-rich units that remain unmixed. Despite the evidence for internal strain, relatively intact clasts of wall rock and microfossils are preserved within the clay. The fault core clay minerology is consistent with a shallow, low temperature authigenesis derived from shearenhanced chemical reactions between wall rocks of contrasting chemistry during sinistral strike-slip. The observed structure is comparable to those of other major weak-cored plate boundaries (e.g., San Andreas fault). Through detailed mapping, we demonstrate that the internal structure of a plate boundary fault core can vary in thickness and composition along-strike over centimetre to meter length scales. 2 Earthquake rupture mechanics critically depend on the physical properties of fault rock assemblages. Therefore, models that investigate rupture propagation at active plate boundaries should incorporate, or else assess tolerance and sensitivity to, variable fault core thickness and composition. SUPPLEMENTARY MATERIAL: Further X-ray diffraction (XRD) analytical data are available at https://doi.org/xxxx';. 3 Understanding the internal structure of large faults is crucial because the chemical and mechanical properties of faults control how earthquakes rupture, nucleate and propagate (e.g., Caine et al. 1996; Wibberley et al. 2008; Faulkner et al. 2010). Geologists studying faults exhumed from depth have shown that they are heterogeneous along-strike and down-dip at a variety of scales (Faulkner et al. 2003;

Journal of Structural Geology, Aug 1, 2016

Joints are conduits for groundwater, hydrocarbons and hydrothermal fluids. Robust fluid flow mode... more Joints are conduits for groundwater, hydrocarbons and hydrothermal fluids. Robust fluid flow models rely on accurate characterisation of joint networks, in particular joint density. It is generally assumed that the predominant factor controlling joint density in layered stratigraphy is the thickness of the mechanical layer where the joints occur. Mechanical heterogeneity within the layer is considered a lesser influence on joint formation. We analysed the frequency and distribution of joints within a single 12-meter thick ignimbrite layer to identify the controls on joint geometry and distribution. The observed joint distribution is not related to the thickness of the ignimbrite layer. Rather, joint initiation, propagation and termination are controlled by the shape, spatial distribution and mechanical properties of fiamme, which are present within the ignimbrite. The observations and analysis presented here demonstrate that models of joint distribution, particularly in thicker layers, that do not fully account for mechanical heterogeneity are likely to underestimate joint density, the spatial variability of joint distribution and the complex joint geometries that result. Consequently, we recommend that characterisation of a layer's compositional and material properties improves predictions of subsurface joint density in rock layers that are mechanically heterogeneous.

Assessing exploration risk requires an analysis of trap, seal, and charge as well as reservoir is... more Assessing exploration risk requires an analysis of trap, seal, and charge as well as reservoir issues. When risking fault bounded structures, across-fault juxtaposition and / or fault membrane seal are key issues. Generally, this work is done on a single "best-guess" technical model.

EGU General Assembly Conference Abstracts, Apr 1, 2018

ABSTRACT Constraining the dynamic feedback between deforming porous media and fluid is crucial fo... more ABSTRACT Constraining the dynamic feedback between deforming porous media and fluid is crucial for understanding hydrocarbon reservoirs, CO2 storage sites and other evolving porous media. In particular, predicting complex fault architecture at depth, currently relies on deterministic algorithms, that do not take account of these dynamic coupling. For instance creation of permeability due to fracturing may permit fluid flow to enter a fault zone, resulting in mineralisation (strengthening) or alteration (weakening) of the fault and host rocks. The resulting changes in rock strength may enhance or retard further fracturing and may even result in a switch of deformation mechanism Temporal evolution of fluid flow through faulted porous rocks has been studied in a field site in SE USA. The field area presents a well-exposed fault system that contains evidence for flow of multiple phases of groundwater with varying chemistries and flow of hydrocarbons. By detailed field mapping and microstructural observations of the fault rocks and of the evidence for fluid flow (e.g. bleaching and hydrocarbon staining) we unravel the fluid flow history and evolving flow properties of the rocks. The 16km long fault presents an erosional scarp of up to 20m high at its centre. This scarp is dissected with canyons that permit cross-sectional views of the fault and associated alteration to be mapped. The field area contains two general classes of lithology. In porous sandstones, deformation is accommodated by deformation bands and fractures. In tight limestones and siltstones deformation is accommodated by fracturing and the formation of clay-rich fault rocks. Evidence for multiple fluid flow events can be observed. Hydrocarbon staining is confined to the coarsest grained layers in the sandstones, and to fractures in all lithologies. Bleaching occurs around small fractures in the fault damage zone and within structural terraces in the fault zone. We present evidence of the evolving structural and geochemical history of the fault zone and discuss how such data can be used to improve predictive capability of fault zone properties at depth where the faults have accommodated syn-faulting fluid flow.

Geological Society, London, Special Publications, Nov 13, 2019

Permian Rotliegend reservoir rocks are generally characterized by high net/gross (N/G) ratios, an... more Permian Rotliegend reservoir rocks are generally characterized by high net/gross (N/G) ratios, and faults in such sand-dominated lithologies are typically not considered likely to seal. Nevertheless, many examples of membrane sealing are present in Rotliegend gas fields in the Southern Permian Basin. This manuscript reviews examples of membrane sealing in the Dutch Rotliegend; it presents an extensive dataset of petrophysical properties of Rotliegend fault rocks and analyses two case studies using commonly used workflows. Fault (membrane) seal studies have been carried out on two Rotliegend fields to test the level of confidence and uncertainty of prediction of 'across fault pressure differences' (AFPD) based on existing SGR-based algorithms. From the field studies it is concluded that observable small AFPDs are present and that these are likely pre-production AFPDs due to exploration-time scale trapping and retention of hydrocarbons. Two shale gouge ratio (SGR)-based empirical algorithms have been used here to estimate AFPDs in lower N/G reservoir intervals with the aim of predicting membrane seal behaviour, and these results are compared to field data. It is concluded the selected SGR-based tools predict AFPD for Upper Rotliegend lower N/G reservoir rocks with reasonable results. Nonetheless, the core sample datasets show a much wider range of permeability and capillary entry pressure than predicted by the selected SGR transforms. This highlights the potential to modify existing workflows for application to faults in high N/G lithologies. Data sharing and collaboration between industry and academics is encouraged, so that in the long run workflows can be developed specifically for faults in high N/G lithologies.

Water Resources Research, Mar 24, 2020

• Cataclastic deformation bands strongly influence the fluid velocity field in a single phase cor... more • Cataclastic deformation bands strongly influence the fluid velocity field in a single phase core flooding experiment. • Cataclastic deformation bands produce capillary barriers that severely limit cross flow between host rock compartments. • The impact of deformation bands, laminae, and experimental boundary conditions are analyzed using numerical simulations.

EGU General Assembly Conference Abstracts, Apr 1, 2019

$Research paper thumbnail of Revealing patterns of enhanced fracture permeability and fluid flow in the footwall damage zone of an active normal fault; the Hurricane Fault at Pah Tempe hot springs, Washington County, Utah$

Many faults grow by the linkage of smaller structures, and damage zones around faults may arise a... more Many faults grow by the linkage of smaller structures, and damage zones around faults may arise as a result of this linkage process. Numerical modelling previously carried out by the authors has shown that, in general, for a homogeneous crystalline rock type, fault zone structures are determined by: the ratio of 1 to 3; the orientation of the pre-existing features to 1; and the initial relative positions of neighbouring joints, specifically, contractional vs. extensional geometries and overlapping vs. under-lapping joints. In this paper we explore what effect increasing the host rock heterogeneity has on the evolving damage zone structures, this is carried out on different scales from a few meters to several kilometers. The heterogeneity was increased by either smoothly varying the material properties within a single rock type or by creating discrete changes by introducing multiple rock types. Different behaviour is predicted for smoothly varying properties and discrete changes. Inc...

The prior knowledge that individuals apply to datasets has an impact on interpretation and model ... more The prior knowledge that individuals apply to datasets has an impact on interpretation and model creation, but the nature of the impact is uncertain. A key question is what factors of a person’s prior knowledge are most influential? Here we have quantified some of the effects of prior knowledge and interpretational methodology on structural model creation for a dataset that supports multiple conceptual models. Geoscientists often work with inherently uncertain data. In resource exploration datasets of different certainties are combined to build a picture of the subsurface by data interpretation and model construction. The concepts used in making interpretation choices are based on prior knowledge. During the interpretation the geoscientist will attempt to validate each concept, often subconsciously sometimes consciously against previous knowledge. Some concepts will be disregarded quickly, others considered more carefully. In this paper we assess the factors which influenced concept...

Fifth International Conference on Fault and Top Seals, 2019