Modelling of interactions between dykes, inclined sheets and faults at Santorini volcano

2021 ◽  
Author(s):  
Kyriaki Drymoni ◽  
John Browning ◽  
Agust Gudmundsson
Keyword(s):  
Tensile Strength ◽  
Fault Zone ◽  
Numerical Models ◽  
Damage Zone ◽  
Sheet Thickness ◽  
Analytical Models ◽  
Energy Conditions ◽  
Dyke Swarm ◽  
Normal Faults ◽  
Santorini Volcano

<p>Dykes and inclined sheets are known occasionally to exploit faults as parts of their paths, but the conditions that allow this to happen are still not fully understood. Here we report field observations from a well-exposed dyke swarm of the Santorini volcano, Greece, that show dykes and inclined sheets deflected into faults and the results of analytical and numerical models to explain the conditions for deflection. The deflected dykes and sheets belong to a local swarm of 91 dyke/sheet segments that was emplaced in a highly heterogeneous and anisotropic host rock and partially cut by some regional faults and a series of historic caldera collapses, the caldera walls providing, excellent exposures of the structures. The numerical models focus on a normal-fault dipping 65° with a damage zone composed of parallel layers or zones of progressively more compliant rocks with increasing distance from the fault rupture plane. We model sheet-intrusions dipping from 0˚ to 90˚ and with overpressures of alternatively 1 MPa and 5 MPa, approaching the fault. We further tested the effects of changing (1) the sheet thickness, (2) the fault-zone thickness, (3) the fault-zone dip-dimension (height), and (4) the loading by, alternatively, regional extension and compression. We find that the stiffness of the fault core, where a compliant core characterises recently active fault zones, has pronounced effects on the orientation and magnitudes of the local stresses and, thereby, on the likelihood of dyke/sheet deflection into the fault zone. Similarly, the analytical models, focusing on the fault-zone tensile strength and energy conditions for dyke/sheet deflection, indicate that dykes/sheets are most likely to be deflected into and use steeply dipping recently active (zero tensile-strength) normal faults as parts of their paths.</p>

scholarly journals Lateral clay injection into normal faults

GeoArabia ◽  
2003 ◽  
Vol 8 (3) ◽  
pp. 501-522
Author(s):  
Wouter van der Zee ◽  
Janos L. Urai ◽  
Pascal D. Richard
Keyword(s):  
Mechanical Properties ◽  
Fault Zone ◽  
Numerical Models ◽  
Clay Content ◽  
Friction Angle ◽  
Fault Gouge ◽  
Analytical Models ◽  
Normal Faults ◽  
Field Observations ◽  
Injection Process

ABSTRACT The clay content of fault gouge is one of the main factors controlling transport and mechanical properties of a fault zone. This paper addresses the process of lateral clay injection into normal faults, which is one of the many processes contributing to the development of clay smear, and can lead to local enrichment of clay in a fault gouge. We combined field observations with geomechanical models to quantify the parameters leading to lateral clay injection into fault zones. Detailed field study shows that a releasing fault bend in a clay layer is required for clay injection to occur. The clay injection process is often associated with the formation of a branch in the fault and the development of a “squeezing block” which injects the clay into the fault zone. A simple analytical model predicts the onset of clay injection when C = σ'v (1 - sin ϕ) / (2 cos ϕ), where C is cohesion (MPa), σ'v is vertical stress (MPa) and ϕ (°) is friction angle. More detailed analysis using 2-D geomechanical finite element models is in good agreement with the analytical models and allows study of the system at higher fault throw. Results of sandbox models containing layers of an elastoplastic clay analogue also compare well with field observations and numerical models, and show the initiation of the releasing step and the evolution of the clay injection process with increasing fault throw. Using our results it is possible to predict the likelihood of lateral clay injection in the subsurface, in settings like the Gharif formation of the Haushi group of Central and South Oman or the Natih formation of North Oman. This requires an estimation of the mechanical properties of the clays at the time of faulting; data which can be obtained from wireline logs and cuttings. This approach to fault seal analysis emphasizes the mechanical aspects of the clay smear process, in addition to the kinematics which were considered in previous analyses. Its application should lead to improved prediction of fault seal processes in the subsurface.

Dating faults, fractures and fluids with U-Pb calcite geochronology: Application to contrasting fracture and fluid-flow modes of the Cleveland Basin

2020 ◽  
Author(s):  
Jack Lee ◽  
Nick Roberts ◽  
Robert Holdworth ◽  
Andrew Aplin ◽  
Richard Haslam ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Fault Zone ◽  
Failure Modes ◽  
Damage Zone ◽  
Source Rocks ◽  
Normal Faults ◽  
Fluid Composition ◽  
Natural Fractures ◽  
Seal Integrity ◽  
Clumped Isotope

<p>Fractures and faults act as important permeable pathways in the subsurface and are of great significance to the petroleum industry and for future Carbon Capture and Storage. Fractures allow fluid-flow through impermeable units such as mudrocks and can affect how these lithologies act as top seals, source rocks and/or unconventional reservoirs. Natural fractures within mudrocks can strongly influence top seal integrity, primary migration and the performance of unconventional (e.g. shale gas) reservoirs. This project studies the exhumed, early-mature, Jurassic mudrock succession of the Cleveland Basin, NE England, combining structural geology with isotope geochemistry and geochronology. The primary objective is to provide an absolute chronology of faulting and fracturing through novel U-Pb geochronology of fracture-fill calcite. The abundance of well-exposed, natural fractures with different orientations and failure modes provides an opportunity to investigate the properties of these fractures, and provide a basin-wide temporal and spatial framework of evolving deformation. The second objective is to use trace element, stable isotope, and clumped isotope analyses, to constrain fluid composition and temperature. In combination, these objectives will provide an integrated understanding of fracturing, faulting and fluid migration during burial and exhumation of a sedimentary basin.</p><p>Current fracture-fill dates from U-Pb geochronology provide intriguing insights into the history of the Cleveland Basin. We have identified and dated three phases of deformation and associated fluid-flow that have contrasting kinematics and fluid-flow regimes. The E-W trending Flamborough Head Fault Zone (FHFZ) bounds the basin to the south, and calcite preserved in one of the major extensional faults provides ages of 64-56 Ma. Calcite from N-S to NNW-SSE trending normal faults and associated fractures in the north of the Cleveland Basin provide ages of 44-25 Ma, revealing a previously unknown phase of Cenozoic faulting, which we speculatively relate to salt-related deformation. Structural and petrographic information suggest that the E-W and N-S trending faults have contrasting fracture-fluid-flow systems. Large (up to 30 cm), chalk hosted, vuggy calcite cements with geopetal sediment-fills in the E-W fault zone suggest it acted as an open fluid conduit with voluminous fluid-flow, linking the shallow sub-surface with deeper levels of the stratigraphy. In contrast, typically thin (<5 mm) vein fills with varying crack-seal-slip type textures in the N-S mudstone-hosted fractures of the Cleveland Basin provide evidence of episodic slip of variable displacement (44-40 Ma); these fracture openings may partly be controlled by pore fluid pressures and pre-date fault movement along the regional Peak Fault and smaller scales N-S faults (40-25 Ma) which are characterised by damage zone calcite mineralisation and extensional jog structures. Initial stable isotopic results are giving indications of fluid temperatures and sourcing which will be built on further by clumped isotope and fluid inclusions work.</p>

scholarly journals Structural characterization of fault damage zones in carbonates (Central Apennines, Italy)

2021 ◽  
Author(s):  
Miriana Chinello ◽  
Michele Fondriest ◽  
Giulio Di Toro
Keyword(s):  
Fault Zone ◽  
Hanging Wall ◽  
Damage Zone ◽  
Normal Fault ◽  
Vertical Displacement ◽  
Fault System ◽  
Normal Faults ◽  
Central Apennines ◽  
Fault Surface ◽  
Fracture Intensity

<p>The Italian Central Apennines are one of the most seismically active areas in the Mediterranean (e.g., L’Aquila 2009, Mw 6.3 earthquake). The mainshocks and the aftershocks of these earthquake sequences propagate and often nucleate in fault zones cutting km-thick limestones and dolostones formations. An impressive feature of these faults is the presence, at their footwall, of few meters to hundreds of meters thick damage zones. However, the mechanism of formation of these damage zones and their role during (1) individual seismic ruptures (e.g., rupture arrest), (2) seismic sequences (e.g., aftershock evolution) and (3) seismic cycle (e.g., long term fault zone healing) are unknown. This limitation is also due to the lack of knowledge regarding the distribution, along strike and with depth, of damage with wall rock lithology, geometrical characteristics (fault length, inherited structures, etc.) and kinematic properties (cumulative displacement, strain rate, etc.) of the associated main faults.</p><p>Previous high-resolution field structural surveys were performed on the Vado di Corno Fault Zone, a segment of the ca. 20 km long Campo Imperatore normal fault system, which accommodated ~ 1500 m of vertical displacement (Fondriest et al., 2020). The damage zone was up to 400 m thick and dominated by intensely fractured (1-2 cm spaced joints) dolomitized limestones with the thickest volumes at fault oversteps and where the fault cuts through an older thrust zone. Here we describe two minor faults located in the same area (Central Apennines), but with shorter length along strike. They both strike NNW-SSE and accommodated a vertical displacement of ~300 m.</p><p>The Subequana Valley Fault is about 9 km long and consists of multiple segments disposed in an en-echelon array. The fault juxtaposes pelagic limestones at the footwall and quaternary deposits at the hanging wall. The damage zone is < 25 m  thick  and comprises fractured (1-2 cm spaced joints) limestones beds with decreasing fracture intensity moving away from the master fault. However, the damage zone thickness increases up to ∼100 m in proximity of subsidiary faults striking NNE-SSW. The latter could be reactivated inherited structures.</p><p>The Monte Capo di Serre Fault is about 8 km long and characterized by a sharp ultra-polished master fault surface which cuts locally dolomitized Jurassic platform limestones. The damage zone is up to 120 m thick and cut by 10-20 cm spaced joints, but it reaches an higher fracture intensity where is cut by subsidiary, possibly inherited, faults striking NNE-SSW.</p><p>Based on these preliminary observations, faults with similar displacement show comparable damage zone thicknesses. The most relevant damage zone thickness variations are related to geometrical complexities rather than changes in lithology (platform vs pelagic carbonates).  In particular, the largest values of damage zone thickness and fracture intensity occur at fault overstep or are associated to inherited structures. The latter, by acting as strong or weak barriers (sensu Das and Aki, 1977) during the propagation of seismic ruptures, have a key role in the formation of damage zones and the growth of normal faults.</p>

scholarly journals Scientific drilling and downhole fluid sampling of a natural CO<sub>2</sub> reservoir, Green River, Utah

2013 ◽  
Vol 16 ◽  
pp. 33-43 ◽  
Author(s):  
N. Kampman ◽  
A. Maskell ◽  
M. J. Bickle ◽  
J. P. Evans ◽  
M. Schaller ◽  
...  
Keyword(s):  
Fault Zone ◽  
Cold Water ◽  
Co2 Storage ◽  
Damage Zone ◽  
Normal Faults ◽  
Charged Fluids ◽  
Green River ◽  
Near Surface ◽  
Navajo Sandstone ◽  
Fluid Sampling

Abstract. A scientific borehole, CO2W55, was drilled into an onshore anticline, near the town of Green River, Utah for the purposes of studying a series of natural CO2 reservoirs. The objective of this research project is to recover core and fluids from natural CO2 accumulations in order to study and understand the long-term consequences of exposure of supercritical CO2, CO2-gas and CO2-charged fluids on geological materials. This will improve our ability to predict the security of future geological CO2 storage sites and the behaviour of CO2 during migration through the overburden. The Green River anticline is thought to contain supercritical reservoirs of CO2 in Permian sandstone and Mississippian-Pennsylvanian carbonate and evaporite formations at depths > 800 m. Migration of CO2 and CO2-charged brine from these deep formations, through the damage zone of two major normal faults in the overburden, feeds a stacked series of shallow reservoirs in Jurassic sandstones from 500 m depth to near surface. The drill-hole was spudded into the footwall of the Little Grand Wash normal fault at the apex of the Green River anticline, near the site of Crystal Geyser, a CO2-driven cold water geyser. The hole was drilled using a CS4002 Truck Mounted Core Drill to a total depth of 322 m and DOSECC’s hybrid coring system was used to continuously recover core. CO2-charged fluids were first encountered at ~ 35 m depth, in the basal sandstones of the Entrada Sandstone, which is open to surface, the fluids being effectively sealed by thin siltstone layers within the sandstone unit. The well penetrated a ~ 17 m thick fault zone within the Carmel Formation, the footwall damage zone of which hosted CO2-charged fluids in open fractures. CO2-rich fluids were encountered throughout the thickness of the Navajo Sandstone. The originally red sandstone and siltstone units, where they are in contact with the CO2-charged fluids, have been bleached by dissolution of hematite grain coatings. Fluid samples were collected from the Navajo Sandstone at formation pressures using a positive displacement wireline sampler, and fluid CO2 content and pH were measured at surface using high pressure apparatus. The results from the fluid sampling show that the Navajo Sandstone is being fed by active inflow of CO2-saturated brines through the fault damage zone; that these brines mix with meteoric fluid flowing laterally into the fault zone; and that the downhole fluid sampling whilst drilling successfully captures this dynamic process.

scholarly journals Gaining a better understanding of the extrusion process in fused filament fabrication 3D printing: a review

2021 ◽  
Author(s):  
Bahaa Shaqour ◽  
Mohammad Abuabiah ◽  
Salameh Abdel-Fattah ◽  
Adel Juaidi ◽  
Ramez Abdallah ◽  
...  
Keyword(s):  
3D Printing ◽  
Numerical Models ◽  
Extrusion Process ◽  
Analytical Models ◽  
Limiting Factor ◽  
Fused Filament Fabrication ◽  
Promising Tool ◽  
Relevant Work ◽  
3D Printing Technique ◽  
Required Quality

AbstractAdditive manufacturing is a promising tool that has proved its value in various applications. Among its technologies, the fused filament fabrication 3D printing technique stands out with its potential to serve a wide variety of applications, ranging from simple educational purposes to industrial and medical applications. However, as many materials and composites can be utilized for this technique, the processability of these materials can be a limiting factor for producing products with the required quality and properties. Over the past few years, many researchers have attempted to better understand the melt extrusion process during 3D printing. Moreover, other research groups have focused on optimizing the process by adjusting the process parameters. These attempts were conducted using different methods, including proposing analytical models, establishing numerical models, or experimental techniques. This review highlights the most relevant work from recent years on fused filament fabrication 3D printing and discusses the future perspectives of this 3D printing technology.

scholarly journals Integrated petrographic – rock mechanic borecore study from the metamorphic basement of the Pannonian Basin, Hungary

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
László Molnár ◽  
Balázs Vásárhelyi ◽  
Tivadar M. Tóth ◽  
Félix Schubert
Keyword(s):  
Compressive Strength ◽  
Fault Zone ◽  
Uniaxial Compressive Strength ◽  
Pannonian Basin ◽  
Damage Zone ◽  
Rock Mechanic ◽  
Fault Rock ◽  
Hydrocarbon Reservoir ◽  
Migration Pathway ◽  
Metamorphic Basement

AbstractThe integrated evaluation of borecores from the Mezősas-Furta fractured metamorphic hydrocarbon reservoir suggests significantly distinct microstructural and rock mechanical features within the analysed fault rock samples. The statistical evaluation of the clast geometries revealed the dominantly cataclastic nature of the samples. Damage zone of the fault can be characterised by an extremely brittle nature and low uniaxial compressive strength, coupled with a predominately coarse fault breccia composition. In contrast, the microstructural manner of the increasing deformation coupled with higher uniaxial compressive strength, strain-hardening nature and low brittleness indicate a transitional interval between the weakly fragmented damage zone and strongly grinded fault core. Moreover, these attributes suggest this unit is mechanically the strongest part of the fault zone. Gougerich cataclasites mark the core zone of the fault, with their widespread plastic nature and locally pseudo-ductile microstructure. Strain localization tends to be strongly linked with the existence of fault gouge ribbons. The fault zone with ∼15 m total thickness can be defined as a significant migration pathway inside the fractured crystalline reservoir. Moreover, as a consequence of the distributed nature of the fault core, it may possibly have a key role in compartmentalisation of the local hydraulic system.

Influence of viscous layers on the growth of normal faults: insights from experimental and numerical models

2003 ◽  
Vol 25 (9) ◽  
pp. 1471-1485 ◽  
Author(s):  
Nicolas Bellahsen ◽  
Jean-Marc Daniel ◽  
Laurent Bollinger ◽  
Evgenii Burov
Keyword(s):  
Numerical Models ◽  
Normal Faults

scholarly journals Modelling the high temperature oxidation of titanium alloys: review of analytical models and development of a new numerical tool PyTiOx

2020 ◽  
Vol 321 ◽  
pp. 06012
Author(s):  
C. Ciszak ◽  
D. Monceau ◽  
C. Desgranges
Keyword(s):  
Numerical Models ◽  
Ecological Impact ◽  
Operating Costs ◽  
Analytical Models ◽  
Temperature Oxidation ◽  
Ti Alloys ◽  
State Diffusion ◽  
First Results ◽  
Aeronautical Industry ◽  
Numerical Tool

In order to limit the ecological impact of air traffic and its operating costs, the aeronautical industry is looking for improving engines efficiencies and substitutes to high density Ni-based superalloys. Thus, a wider use of Ti-alloys operating at higher temperatures is one of the developed solutions. Being able to predict as accurately as possible the oxidation behavior of Ti-based components at high temperatures appears therefore crucial to improve their sizing and durability. Analytical models based on the solid-state diffusion laws can be found in the litterature. They are fairly accurate in most cases, but they reveal some intrinsic limitations in specific cases such as temperature transients or thin components. Numerical models were later developed to break down these limitations. First results from a new numerical tool called “PyTiOx” (still under development are presented here. They confirm the intrinsic limitations of analytical models. In the case of thin samples, the numerical model predicts an increase of scaling kinetic when metal becomes O-saturated, whereas analytical models do not.

scholarly journals Nonlinear processes in the bunched electron beams of high-power klystrons and the limits of analytical and one-dimensional numerical models applicability for their analysis.

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
V.Y. Rodyakin ◽  
◽  
V.M. Pikunov ◽  
V.N. Aksenov ◽  
◽  
...  
Keyword(s):  
Electron Beam ◽  
High Power ◽  
Numerical Models ◽  
Nonlinear Effects ◽  
Analytical Models ◽  
Modulation Amplitude ◽  
Two Dimensional ◽  
One Dimensional ◽  
Charge Parameter ◽  
Program Data

We present the results of a comparative theoretical analysis of the electron beam bunching in a single-stage klystron amplifier using analytical models, a one-dimensional disk program, and a two-dimensional program. Data on the influence of various one-dimensional and two-dimensional nonlinear effects on the efficiency of electron beam bunching at different values of the space charge parameter and the modulation amplitude are presented. The limits of applicability of analytical and one-dimensional numerical models for electron beam bunching analysis in high-power klystron amplifiers are found.

Partitioned Permeability Diagram: an innovative way to estimate Fault Zones hydraulics.

2021 ◽  
Author(s):  
Irène Aubert ◽  
Juliette Lamarche ◽  
Philippe Leonide
Keyword(s):  
Fault Zone ◽  
Damage Zone ◽  
Fault Zones ◽  
Matrix Permeability ◽  
Vertical Fault ◽  
Core Permeability ◽  
The Impact ◽  
Evolution With Time ◽  
Fluid Pathway

&lt;p&gt;Understanding the impact of fault zones on reservoir trap properties is a major challenge for a variety of geological ressources applications. Fault zones in cohesive rocks are complex structures, composed of 3 components: rock matrix, damage zone fractures and fault core rock. Despite the diversity of existing methods to estimate fault zone permeability/drain properties, up to date none of them integrate simultaneously the 3 components of fracture, fault core and matrix permeability, neither their evolution with time. We present a ternary plot that characterizes the fault zones permeability as well as their drainage properties. The ternary plot aims at (i) characterizing the fault zone permeability between the three vertices of matrix, fractures and fault core permeability ; and at (ii) defining the drain properties among 4 possible hydraulic system: (I) good horizontal and vertical, fault-perpendicular and -parallel; (II) moderate parallel fluid pathway; (III) good parallel fault-core and (IV) good parallel fractures. The ternary plot method is valid for 3 and 2 components fault zones. The application to the Castellas Fault case study show the simplicity and efficiency of the plot for studying underground and/or fossil, simple or polyphase faults in reservoirs with complete or limited permeability data.&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document