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

<p>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.</p>

Permeability contrasts of fault zones - from conceptual model to numerical simulation

2020 ◽  
Author(s):  
Ulrich Kelka ◽  
Thomas Poulet ◽  
Luk Peeters
Keyword(s):  
Fluid Flow ◽  
Fault Zone ◽  
Large Scale ◽  
Regional Scale ◽  
Damage Zone ◽  
Fluid Pressure ◽  
Fault Zones ◽  
Strong Impact ◽  
Fault Zone Architecture ◽  
The Impact

<p>Fault and fracture networks can govern fluid flow patterns in the subsurface and predicting fluid flow on a regional scale is of interest in a variety of fields like groundwater management, mining engineering, energy, and mineral resources. Especially the pore fluid pressure can have a strong impact on the strength of fault zones and might be one of the drivers for fault reactivation. Reliable simulations of the transient changes in fluid pressure need to account for the generic architecture of fault zones that comprises strong permeability contrast between the fault core and damage zone.</p><p>Particularly, the distribution and connectivity of large-scale fault zones can have a strong impact on the flow field. Yet, modelling numerically such features in their full complexity remains challenging. Often faults zones are conceptualized as forming exclusively either barriers or conduits to fluid flow. However, a generic architecture of fault zones often comprises a discrete fault core surrounded by a diffuse damage zone and conceptualizing large scale discontinuities simply as a barrier or conduit is unlikely to capture the regional scale fluid flow dynamics. It is known that if the fault zone is hosted in low-permeability strata, such as clays or crystalline rocks, a transversal flow barrier can form along the fault core whereas the fracture-rich fault damage zone represents a longitudinal conduit. In more permeable host-rocks (i.e. sandstones or carbonates) the reverse situation can occur, and the permeability distributions in the damage zones can be governed by the abundance of low-permeability deformation features. A reliable numerical model needs to account for the difference and strong contrasts in fluid flow properties of the core and the damage zone, both transversally and longitudinally, in order to make prediction about the regional fluid flow pattern.</p><p>Here, we present a numerical method that accounts for the generic fault zone architecture as lower dimensional interfaces in conforming meshes during fluid flow simulations in fault networks. With this method we aim to decipher the impact of fault zone architecture on subsurface flow pattern and fluid pressure evolution in fractures and faulted porous media. The method is implemented in a finite element framework for Multiphysics simulations. We demonstrate the impact of considering the more generic geological structure of individual faults on the flow field by conceptualizing discontinuities either as barriers, conduits or as a conduit-barrier system and show were these conceptualizations are applicable in natural systems. We further show that a reliable regional scale fluid flow simulation in faulted porous media needs to account for the generic fault zone architecture. The approach is finally used to evaluate the fluid flow response of statistically parameterised faulted media, in order to investigate the impact and sensitivity of each variable parameter.</p>

Thermophysical reservoir properties of the Hauptdolomit-facies underneath the Viennese basin across fault zones analogues – a reservoir study for the GeoTief EXPLORE project

2020 ◽  
Author(s):  
Doris Rupprecht ◽  
Sven Fuchs ◽  
Andrea Förster ◽  
Mariella Penz-Wolfmayr
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Fractured Rocks ◽  
Damage Zone ◽  
Fault Zones ◽  
Rock Properties ◽  
Zone Model ◽  
Geothermal Resources ◽  
Fault Rocks ◽  
The Impact

<p>The GeoTief EXPLORE project aims to explore the geothermal potential and quantify the geothermal resources of the Vienna Basin (Austria) and the underlying Northern Calcareous Alpine basement. The main target of geothermal interest is the massive and tectonically remolded Hauptdolomite facies that has been identified as potential geothermal reservoir in previous studies. Now, this formation is studied using outcrop analogues for the investigation of their petrophysical characterization and specific thermal properties (thermal conductivity and thermal diffusivity).</p><p> </p><p>Here, we report new measurements on a total of 60 samples from 6 outcrops in and around the area of Vienna applying different methods for the laboratory measurement of thermal and hydraulic rock properties. The petrophysical analysis considers the impact of deformation along and across fault zones, which introduces heterogeneity of storage properties and consequently in the thermophysical properties. Using the standard fault core and damage zone model, outcrop samples were grouped into unfractured and fractured protoliths, as well as in fault rocks, like breccias and cataclasites. Rock samples are then classified by their fracture density (m² fracture surface per m³ rock) and by their matrix content and differences in grain sizes, respectively.</p><p> </p><p>The measured thermal rock properties vary significantly between the selected rock groups. The total range [90 % of values] is between 3.2 and 5.0 W/(mK) for thermal conductivity and between 1.3 and 2.7 mm²/s for thermal diffusivity. The results generally met the expected trend for fractured rocks as conductivity and diffusivity decreases with increasing porosity under unsaturated and saturated conditions. The total porosities are less than 5%. The variability of thermal conductivity under saturated conditions shows complex trends depending on the different rock classifications where fault rocks and highly fractured rocks of the damage zone show lower increase in thermal conductivities.</p><p> </p><p>The new petrophysical characterization will be the base for further numerical investigations of the hydraulic and thermal regime as well as for the analysis of the geothermal resources of the Hauptdolomite.</p><p> </p><p> </p><p> </p><p> </p>

Seismic imaging and statistical analysis of fault facies models

2017 ◽  
Vol 5 (4) ◽  
pp. SP71-SP82 ◽  
Author(s):  
Dmitriy R. Kolyukhin ◽  
Vadim V. Lisitsa ◽  
Maxim I. Protasov ◽  
Dongfang Qu ◽  
Galina V. Reshetova ◽  
...  
Keyword(s):  
Fault Zone ◽  
Seismic Data ◽  
Structural Complexity ◽  
Fault Zones ◽  
Rock Properties ◽  
Zone Structure ◽  
Structure And Property ◽  
Subsurface Fluid ◽  
The Impact ◽  
Seismic Images

Interpretation of seismic responses from subsurface fault zones is hampered by the fact that the geologic structure and property distributions of fault zones can generally not be directly observed. This shortcoming curtails the use of seismic data for characterizing internal structure and properties of fault zones, and it has instead promoted the use of interpretation techniques that tend to simplify actual structural complexity by rendering faults as lines and planes rather than volumes of deformed rock. Facilitating the correlation of rock properties and seismic images of fault zones would enable active use of these images for interpreting fault zones, which in turn would improve our ability to assess the impact of fault zones on subsurface fluid flow. We use a combination of 3D fault zone models, based on empirical data and 2D forward seismic modeling to investigate the link between fault zone properties and seismic response. A comparison of spatial statistics from the geologic models and the seismic images was carried out to study how well seismic images render the modeled geologic features. Our results indicate the feasibility of extracting information about fault zone structure from seismic data by the methods used.

scholarly journals On morphology and amplitude of 2D and 3D thermal anomalies induced by buoyancy-driven flow within and around fault zones

2020 ◽  
Author(s):  
Laurent Guillou-Frottier ◽  
Hugo Duwiquet ◽  
Gaëtan Launay ◽  
Audrey Taillefer ◽  
Vincent Roche ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Fault Zone ◽  
3D Models ◽  
Fault Zones ◽  
Rock Properties ◽  
Thermal Anomalies ◽  
Flow Models ◽  
Temperature Anomalies ◽  
Vertical Fault ◽  
Dip Angle

Abstract. In the first kilometres of the subsurface, temperature anomalies due to heat conduction processes rarely exceed 20–30 °C. When fault zones are sufficiently permeable, fluid flow may lead to thermal anomalies much higher, as evidenced by the emergence of thermal springs or by fault-related geothermal reservoirs. Hydrothermal convection triggered by buoyancy effects creates thermal anomalies whose morphology and amplitude are not well known, especially when depth- and time-dependent permeability are considered. Exploitation of shallow thermal anomalies for heat and power production partly depends on the volume and on the temperature of the hydrothermal reservoir. This study presents a non-exhaustive numerical investigation of fluid flow models within and around simplified fault zones, where realistic fluid and rock properties are accounted for, as well as appropriate boundary conditions. 2D simplified models point out relevant physical mechanisms for geological problems, such as thermal inheritance or splitting plumes showing a pulsating behaviour. When permeability is increased, the classic finger-like upwellings evolve towards a bulb-like geometry, resulting in a large volume of hot fluid at shallow depth. In the simplified 3D models, where fault zone dip angle and fault zone thickness are varied, the anomalously hot reservoir exhibits a kilometre-sized hot air balloon morphology, or, when permeability is depth-dependent, a funnel-shape geometry. For thick faults, the number of thermal anomalies increases but not the amplitude. The largest amplitude (up to 80–90 °C) is obtained for vertical fault zones. At the top of a vertical, 100 m wide, fault zone, temperature anomalies greater than 30 °C may extend laterally over more than 1 km from the fault boundary. These preliminary results should motivate further geothermal investigations of more elaborated models where topography and fault intersections would be accounted for.

scholarly journals Fault sealing and caprock integrity for CO<sub>2</sub> storage: an in-situ injection experiment

2020 ◽  
Author(s):  
Alba Zappone ◽  
Antonio Pio Rinaldi ◽  
Melchior Grab ◽  
Quinn Wenning ◽  
Clément Roques ◽  
...  
Keyword(s):  
Fiber Optics ◽  
Fault Zone ◽  
Co2 Storage ◽  
Damage Zone ◽  
Laboratory Data ◽  
Wide Range ◽  
Clay Formation ◽  
The Impact ◽  
Injection Experiment

Abstract. The success of geological carbon storage depends on the assurance of a permanent confinement of the injected CO2 in the storage formation at depth. One of the critical elements of the safekeeping of CO2 is the sealing capacity of the caprock overlying the storage formation, despite faults and/or fractures, which may occur in it. In this work, we present an ongoing injection experiment performed in a fault hosted in clay at the Mont Terri underground rock laboratory (NW Switzerland). The experiment aims at improving our understanding on the main physical and chemical mechanisms controlling i) the migration of CO2 through a fault damage zone, ii) the interaction of the CO2 with the neighbouring intact rock, and iii) the impact of the injection on the transmissivity in the fault. To this end, we inject a CO2-saturated saline water in the top of a 3 m think fault in the Opalinus Clay, a clay formation that is a good analogue of common caprock for CO2 storage at depth. The mobility of the CO2 within the fault is studied at decameter scale, by using a comprehensive monitoring system. Our experiment aims to the closing of the knowledge gap between laboratory and reservoir scales. Therefore, an important aspect of the experiment is the decameter scale and the prolonged duration of observations over many months. We collect observations and data from a wide range of monitoring systems, such as a seismic network, pressure temperature and electrical conductivity sensors, fiber optics, extensometers, and an in situ mass spectrometer for dissolved gas monitoring. The observations are complemented by laboratory data on collected fluids and rock samples. Here we show the details of the experimental concept and installed instrumentation, as well as the first results of the preliminary characterization. Analysis of borehole logging allow identifying potential hydraulic transmissive structures within the fault zone. A preliminary analysis of the injection tests helped estimating the transmissivity of such structures within the fault zone, as well as the pressure required to mechanically open such features. The preliminary tests did not record any induced microseismic events. Active seismic tomography enabled a sharp imaging the fault zone.

Discrete and continuous conceptual models of fault zones.

2021 ◽  
Author(s):  
Tom Manzocchi
Keyword(s):  
Numerical Model ◽  
Conceptual Model ◽  
Fault Zone ◽  
Large Scale ◽  
Damage Zone ◽  
Fault Zones ◽  
Zone Model ◽  
Multiple Model ◽  
Modelling Studies ◽  
Scale Properties

&lt;p&gt;Faults can control the large-scale properties of rock volumes through their behaviour as flow conduits and/or barriers or by localising geomechanical effects. Hence, often the fidelity of a numerical model of faulted site relies on the accuracy with which the fault zone is represented.&amp;#160; There are two distinct factors that must be considered in a modelling study: first, does the model contain the most relevant characteristics of the fault that influence the behaviour of interest; and second, are these characteristics assigned realistic and representative values that capture both their natural variability and the uncertainty with which they can be determined for the specific case of interest. These two factors are contained in the conceptual fault model and choice of modelling proxy-properties, respectively.&lt;/p&gt;&lt;p&gt;In recent years, two classes of conceptual fault zone model have dominated the description of fault zones, broadly characterised by either a continuous or a discrete approach. Continuous fault zone properties (e.g. fault core and damage zone thickness, displacement partitioning statistics) often show high variability which many modelling studies attempt to capture by running multiple model containing property values sampled from the distribution. Discrete descriptions focus on the presence of individual fault zone elements (e.g. shale smears, relay zones), and models guided by a discrete conceptual model attempt to place representative frequencies of elements. A single discrete model might contain the same property distributions as an ensemble of continuous models yet, because it contains a representative frequency of different elements, its behaviour might lie beyond the extreme behaviour of the continuous ensemble. Hence, the manner in which a geologist&amp;#8217;s conceptual model is represented in a modeller&amp;#8217;s numerical model can be hugely important for the outcome of the study, and it is in the interest of both modellers and geologists to ensure that they have a correct understanding of the other&amp;#8217;s part of the process.&lt;/p&gt;

Imaging fine seismic structures of faults with fault-zone trapped waves

2020 ◽  
Author(s):  
Hui Su ◽  
Yuanze Zhou
Keyword(s):  
Fault Zone ◽  
Earthquake Prediction ◽  
Transport Theory ◽  
Damage Zone ◽  
Fault Zones ◽  
Physical Parameters ◽  
Trapped Waves ◽  
Low Velocity ◽  
Velocity Models ◽  
Before And After

&lt;p&gt;A fault is a low-velocity zone with widely distributed scatterers compared to the surrounding uniform materials because of the highly damaged rocks in its core. When seismic waves travel through faults, they will reflect on boundaries multiply and be trapped in the fault zones which cause the energy redistribution and generate coda waves with complicated characteristics after the direct P- and S- waves. The coda is named fault-zone trapped waves (FZTWs) (Li et al., 1990). The amplitude and duration characteristics of FZTWs (Li et al., 2016) can be used to constrain the geometric features of the fault and the physical parameters of the scatterers, so the fine structure of the fault can be finally obtained. We observed some FZTWs at several Hi-net stations in Japan, which were generated by low magnitude aftershocks following large earthquakes. Relatively strong FZTWs can be recorded by the seismic stations near or on the fault where the events happened. In this study, we simulate the theoretic envelops of FZTWs with radiative transport theory (Sanborn et al., 2017) for possible velocity models with scatterers described with von Karman distribution (Sato et al., 2012). While the theoretical envelops of FZTWs fit the observed ones well, &amp;#160;the fine fault model is determined. The FZTWs from different events before and after the main shock can be used to determine the physical properties of faults and their adjoint area varied in the seismogenic process, then we can deeply understand the fault evolutions before and after earthquakes. The varying properties of faults can provide a new perspective for earthquake preparation and a new reference for earthquake prediction and promotes the development of earthquake prediction.&lt;br&gt;Li, Y. G., R. D. Catchings, and M. R. Goldman. 2016, Subsurface Fault Damage Zone of the 2014Mw 6.0 South Napa, California, Earthquake Viewed from Fault&amp;#8208;Zone Trapped Waves. Bulletin of the Seismological Society of America, 106, no. 6,2747-2763. doi: 10.1785/0120160039.&lt;br&gt;Li, Y. G., P. Leary, K. Aki, and P. Malin. 1990, Seismic Trapped Modes in the Oroville and San-Andreas Fault Zones. Science, 249, no. 4970,763-766. doi: 10.1126/science.249.4970.763.&lt;br&gt;Sanborn, C. J., V. F. Cormier, and M. Fitzpatrick. 2017, Combined Effects of Deterministic and Statistical Structure on High-frequency Regional Seismograms. Geophysical Journal International, 210, no. 2,1143-1159. doi: 10.1093/gji/ggx219.&lt;br&gt;Sato H., Fehler M.C. 2012, Seismic Wave Propagation and Scattering in the Heterogeneous Earth, 2nd edn, Springer-Verlag.&lt;/p&gt;

Continuous Permeability Measurements Record Healing Inside the Wenchuan Earthquake Fault Zone

Science ◽  
2013 ◽  
Vol 340 (6140) ◽  
pp. 1555-1559 ◽  
Author(s):  
Lian Xue ◽  
Hai-Bing Li ◽  
Emily E. Brodsky ◽  
Zhi-Qing Xu ◽  
Yasuyuki Kano ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Fault Zone ◽  
Damage Zone ◽  
Fault Zones ◽  
Deep Borehole ◽  
Earthquake Fault ◽  
Hydraulic Diffusivity ◽  
The Wenchuan Earthquake ◽  
Direct Measurements ◽  
Observation Period

Permeability controls fluid flow in fault zones and is a proxy for rock damage after an earthquake. We used the tidal response of water level in a deep borehole to track permeability for 18 months in the damage zone of the causative fault of the 2008 moment magnitude 7.9 Wenchuan earthquake. The unusually high measured hydraulic diffusivity of 2.4 × 10−2square meters per second implies a major role for water circulation in the fault zone. For most of the observation period, the permeability decreased rapidly as the fault healed. The trend was interrupted by abrupt permeability increases attributable to shaking from remote earthquakes. These direct measurements of the fault zone reveal a process of punctuated recovery as healing and damage interact in the aftermath of a major earthquake.

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