bluuebunny/crossref_metadata_2025_split huggingface dataset:
EPOS Thematic Core Service Anthropogenic Hazards - Open-Access Integrated Infrastructures for Research and Innovation in the Area of Anthropogenic Seismicity Associated with the Exploitation of Georesources
Authors: Lasocki S. , Orlecka-Sikora B. , Rudzinski L. , Lelonek M. , Kocot J. , Jones G. , Garcia-Aristizabal A. 
Published: September 2022

ABSTRACT:
EPOS Thematic Core Service ANTHROPOGENIC HAZARDS (TCS AH) integrates, within the framework of the European Plate Observing System (EPOS) (www.epos-eu.org), research infrastructures freely open for scientists, engineers, and all others interested in hazards posed by the seismicity induced by geo-resource exploration and exploitation. The integrated infrastructures consist of three components:
•Data gathered in "episodes." An episode is a set of time-correlated geophysical and technological data and other relevant geo-data that comprehensively report anthropogenic seismicity cases and the industrial and geological conditions of these processes.
•Applications, i.e., problem-oriented, bespoke, and standard software tools to process and analyze the data. They help relate seismicity and technological factors for hazard assessment and other scientific targets.
•The episodes and applications are accessible on the EPISODES e-platform (https://tcs.ah-epos.eu), an IT environment for data modeling and analysis. The platform provides the user’s workspace, adequate hardware resources, including HPC systems and other facilities that grant quick and efficient execution of commissioned tasks. Here we present and describe the structure and details of this open-access facility. On an example of the pilot "Time-Dependent Anthropogenic Seismic Hazard Assessment," we demonstrate the potential of the integrated infrastructures for developing innovative practice solutions, ready-for-implementation in geo-resource exploitation.

1. INTRODUCTION
Exploitation of geo-resources alters the stress and strength conditions in the engaged rock mass. In favorable conditions such alterations result in rock fracturing and violent emission of seismic waves. This process known as anthropogenic seismicity is an unwanted response of the rock mass to the technological processes. With rising demands for energy and minerals, anthropogenic seismicity has been appearing in association with diverse technological processes, and often also in previously aseismic regions. The induced or triggered earthquakes can accompany underground and open-pit mining, conventional and unconventional hydrocarbon extraction, geothermal energy production, underground liquid and gas storage including carbon sequestration, impoundment of surface reservoirs of liquids (like artificial lakes of dammed water for hydroelectric plants and ore-floatation waste repositories) and many other technological processes that perturb the boundary conditions in the affected rock (Lasocki and Orlecka-Sikora, 2020).
Dynamic Fracture Network Evolution: Monitoring and Characterizing Using a Geomechanically Constrained Time-Lapsed Windowed Microseismic Imaging
Authors: Gentry E. N. , Soroush H. , Batir J. , Aminzadeh F. 
Published: September 2022

ABSTRACT:
To create an efficient subsurface heat exchanger in an Enhanced geothermal System (EGS), it is essential to have a thorough understanding of the subsurface characteristics along with an effective real-time system to monitor and map the changes in induced and natural fractures during stimulation and production. The ability to monitor the variation in fracture network characteristics is necessary to evaluate reservoir performance over time. These continuous assessments provide valuable information and an opportunity to optimize stimulation schemes for maximum heat production. We developed a methodology for analysis of microseismic data through a novel "Time-Lapsed Microseismic" (TLM) technique combined with a Moment Tensor Inversion (MTI) method, to detect, locate and geomechanically characterize microseismic events in different time windows for monitoring the changes in the fracture network’s geometry and geomechanical status over time without requiring additional data acquisition or monitoring tools. 41 years of raw waveform data from multiple generations of seismic networks from the Geysers geothermal field were amalgamated to generate a catalog of 9,601 stable full-waveform MTI solutions in a rapid time frame. The resulting TLM data are the foundation for monitoring the temporal changes in fracture characteristics. Furthermore, as new microseismic data are collected, the TLM volume is updated, rendering itself to become a primary EGS monitoring tool.

1. INTRODUCTION
The long-term productivity of an EGS is controlled by the temporal evolution of induced fractures in geothermal reservoirs because the fracture network is the path by which heat (resource) is extracted from the subsurface. Therefore, it is essential to monitor the variation in fracture network characteristics over time to assess reservoir performance. These updated assessments provide valuable information and an opportunity to optimize stimulation schemes for maximum heat production.
To monitor fracture evolution through time, geomechanically analyzing these unexpected reservoir behaviors is needed to better understand the reservoir dynamics and the role of hydraulic shearing, which can potentially alter the near-well and far-field permeability structure (Soroush et al., 2018). One of the readily available datasets for subsurface monitoring is microseismic monitoring. If the signature of hydraulic shearing of fractures (which are the main sources of microseismicity) in microseismic data can be captured, then identification and characterization of fracture evolution can be automated using artificial intelligence. Therefore, the integration of advanced geophysical and geomechanical analysis workflows, augmented by artificial intelligence, seems to have vast potential in providing low-cost solutions for monitoring fractures’ evolution and conductivity in real-time.
Waveform Similarity of Micro-Seismicity at the ToC2ME Hydraulic Fracturing Experiment Site
Authors: Yang Jin , Li Bing 
Published: September 2022

ABSTRACT:
This study quantitatively investigates the waveform similarity of micro-earthquakes detected during the Tony Creek Dual Microseismic Experiment (ToC2ME) conducted near Fox Creek, Alberta. Subsurface anthropogenic activities, especially processes involving injection, can lead to accumulation of pore pressure and elastic strain among the geologic formations and rocks, resulting in induced earthquakes. Four hydraulic-fracturing treatment wells were stimulated in the middle of the study area. An acquisition system monitored continuous seismic waveforms from 25 October to 15 December 2016 revealing 4083 hydraulic fracture-related events with magnitude ranging from Mw from -1 to 3.2. The present study compares and discusses similarity of waveforms captured by these stations using the PageRank method to form families of similar waveforms and rank their relative importance within their family. Waveforms corresponding to earthquake events are extracted from 3 representative stations for analysis. Preliminary results reveal earthquake families spatially gathered around the injection wells. Of the three main clusters located in the center, west, and east of the well, the central cluster showed the widest range of PageRank values, and also contained the highest PageRank value events. Events that happened before injection programme are more likely to have high PageRank values. There is also a slight positive correlation between PageRank value and magnitude. Overall, early events have more direct or indirect links than subsequent events.

1. INTRODUCTION
Documented earthquakes events in North America have shown a dramatic increase in the past two decades, especially in northwestern and southern United States and western Canada. Previous research notes the emergence of small-scale earthquakes that are closely related to human activities, especially hydraulic fracturing and saltwater disposal (Atkinson et al., 2014, Konstantinovskaya et al., 2021, Schultz et al., 2020). This can partially be attributed to the implementation of improved monitoring technologies with higher capability for capturing earthquake events below a local magnitude (ML) of 2.5, denoted as micro-earthquakes.
How Static Stiffness Is Affected by Non-Elastic Deformations in Different Lithologies
Authors: Lozovyi S. , Fjær E. , Mews K. S. , Giger S. B. 
Published: September 2022

ABSTRACT:
The purpose of this work is to study the evolution of non-elastic deformations and their effect on static stiffness prior to reaching plastic yield. To this end, a series of geomechanical laboratory experiments on preserved rock cores of various lithologies is performed. The experiments include probing of static stiffness on saturated core samples in loading-unloading undrained cycles. Test results are used to obtain parameters that describe the non-elastic response of stress-strain relation. Further, the non-elastic parameters are implemented in an empirical model to evaluate the dependence of stiffness on applied triaxial stress amplitude. Results show that for almost all tested rocks, Young’s modulus and Poisson’s ratio are dependent on stress change during triaxial loading/unloading well before reaching plastic yield. In order to study the factors influencing non-elastic processes, correlations between the computed non-elastic parameters and rock properties such as porosity, mineralogy and stiffness were established.

1. INTRODUCTION
It is known that rocks are not linear elastic media and deviate from purely elastic response already at micro-strain level (Winkler et al. 1979). However, in practical geomechanical applications, linear elasticity is often assumed until the strain reaches plastic yield. This assumption may lead to false predictions of stress-strain changes in the subsurface during e.g., hydrocarbon reservoir depletion or injection, geotechnical operations, or long-term nuclear waste storage. In laboratory rock-mechanical test results, stiffness is usually reported as constant values, independent of stress/strain amplitude changes. However, using only a few additional parameters, non-linearity can be addressed by linearizing the compliance function versus stress for static loading/unloading as described below.
In soil mechanics, Kondner (1963) demonstrated that a hyperbolic function can approximate non-linear stress-strain curves for both sand and clay with a high degree of accuracy. On transformed axes, hyperbolae can be plotted as a linear function. Therefore, non-elastic behavior can be described by only two coefficients a and b. a is the inverse of the initial tangent modulus, and b is the inverse of the asymptotic value of the stress difference, which the stress-strain curve approaches at infinite strain.
Verification of a Distributed Fiber Optic Sensing Slope Stability Monitoring Solution
Authors: Clarkson P. , Cole S. , Godfrey A. , Crickmore R. , Minto C. , Watlet A. , Whiteley J. , Chambers J. , Boyd J. , Dashwood B. 
Published: September 2022

ABSTRACT:
This paper describes the testing of a novel ground condition and slope stability monitoring system based on Distributed Rayleigh Sensing (DRS) on a landslide observatory operated by the British Geological Survey (BGS). The DRS system uses the backscattered light from buried fiber optic cables to determine the strain and temperature at any point along the fiber up to distances of over 50 km and has been shown to respond to ground movement, moisture content changes and temperature variations. The output of the fiber is compared to that expected based on the known geology of the slope and other instruments such as tiltmeters and moisture content sensors. In addition to long-term strain and temperature measurements, the system can also sense acoustic vibrations and can be used to make active and passive seismic surveys to give a comprehensive 3D picture of the subsurface state. The results show that the DRS system can provide improved spatial and time resolution and sensitivity to give a more comprehensive and detailed picture of slope behavior than would otherwise be possible. Such detail allows improved landslide prediction methods and early warning systems to be developed.

1. INTRODUCTION
Slope stability monitoring is important for failure detection and prediction and for greater understanding of slope behavior. Slope stability depends on several slope characteristics and there are a wide range of measurement methods that can increase such understanding. Fiber optic based sensing approaches are widely used for infrastructure monitoring and are increasingly being used for structural integrity and slope stability assessment due to their high sensitivity and spatial coverage and resolution. Such systems usually either operate at acoustic frequencies (as in Distributed Acoustic Sensing (DAS) systems) or at lower frequencies as Distributed Strain Sensing (DSS) systems. DAS systems operate by monitoring phase changes in Rayleigh backscattered light from pulses transmitted down an optical fiber. These phase changes occur due to small strain and temperature induced variations in the refractive index of the fiber. Most systems based on Rayleigh sensing are AC coupled to strain and are not used to perceive strain changes over longer timescales. As such, they have primarily been used for event detection and until recently had limited applicability for longer term condition monitoring and event prediction. However, recent advances in the technology have enabled absolute strain changes to be measured over much longer timescales using Distributed Rayleigh Sensing (DRS) systems. This leads to a wider range of applications, for example slope stability monitoring.
An Experimental Study of Fracture-Induced Chemical Reactions
Authors: Carey J. W. , Frash L. P. , Hicks W. , Menefee A. H. 
Published: September 2022

ABSTRACT:
Fracturing of rock allows ingress of fluids that may be chemically distinct from native pore fluids. These external fluids can induce dissolution and precipitation, which may be enhanced by highly reactive, comminuted material and metastable highly deformed materials. Reaction products have important feedbacks via dissolution of asperities that affect fracture strength and friction properties. In this study, we examine dynamic fracturing of anhydrite/dolomite using triaxial direct-shear experiments with simultaneous x-ray radiography and tomography. The impermeable cores were fractured at a temperature of 50°C and a confining pressure of 3.5 MPa while being exposed to 500 kPa injection pressure of concentrated (18 wt%) BaCl2 solution. Once fractured, the barium solution invaded the primary shear fracture and the surrounding damaged region. X-ray radiographs and tomography revealed precipitation of barium sulfate and carbonate (barite/witherite). Despite the precipitation, the permeability of the fracture system changed little following the initial fracturing event. Precipitation was likely confined to relatively stagnant flow regions, with more open regions sustaining high flow rates. The experimental results demonstrate laboratory-induced fluid-rock reaction and precipitation in fracture systems and reveal the important role of grain-scale mineralogy and flow pathways on the extent of reaction and the impact of precipitation on permeability.

1. INTRODUCTION
Fracturing of rock allows the ingress of fluids that may be chemically distinct from the native pore fluids. These external fluids can induce chemical reactions that are extremely challenging to anticipate or monitor, as they are a complex function of both intermixing among external and native fluids and reactions with the mineralogy of the host rock. The primary reactions of interest are dissolution of primary minerals and precipitation of secondary minerals, which can alter both fracture and void space sufficiently to change critical transport and rock mechanical properties (e.g., Viswanathan et al. 2022). The fracturing process itself can produce highly reactive, comminuted material that can accelerate these types of geochemical reactions. In addition, the complex geometry of fracture systems creates large variations in the ratio of reactive surface area to fluid volume (i.e., tensile opening versus closed shear; Menefee et al. 2020). Furthermore, fracturing under intense shear can generate highly reactive, metastable materials (e.g., heavily deformed crystals, amorphous material, glass) that lead to non-equilibrium precipitates. Such reaction products have important implications for the hydraulic and mechanical evolution of geologic systems, but their formation and growth depend on an array of widely variable reservoir conditions (e.g., geochemistry, mineralogy, temperature/pressure, flow rate, permeability) and thus are poorly constrained.
Correlation of Near Surface Geotechnical and Geophysical Parameters for Six Bridge Sites in Central Montana
Authors: Barrick D. J. , Link C. A. , MacLaughlin M. M. , Berry S. M. 
Published: September 2022

ABSTRACT:
Results are presented from tests performed for the replacement of six timber bridges in Central Montana. The sites consist of Cretaceous sedimentary rocks overlain by thin layers of residual clays or Quaternary alluvium. Samples of the overlying materials were collected to supplement 43 core and Shelby tube samples from borings. Laboratory tests were performed resulting in values for static modulus, moisture content, unit weight, and peak compressive strength. Geophysical investigations were also completed at the site using four methods: refraction tomography (SRT), shear-wave analysis (MASW), electrical resistivity tomography, and induced polarization tomography. Geophysical values were extracted from the final 2D tomogram and compared with geotechnical borehole data at the same depths. These geophysical and geotechnical values were used as inputs and targets in a Feedforward Neural Network (FNN). The goal of the FNN analysis is to determine whether a relationship can be mapped between the geophysical and geotechnical values. Such a relationship would allow future investigation via nondestructive experimental techniques and provide confidence in using geophysical site investigations where geotechnical drilling cannot be performed. Our results from FNN analysis suggest a high confidence of predicting common geotechnical parameters from independent geophysical data for sedimentary rocks in Central Montana.

1. PROJECT BACKGROUND AND GOALS
This study was conducted during a geotechnical site investigation for replacement of six timber bridges between Lewistown and Grass Range, Montana on Highway MT-200. The limits of the locations of the bridges (numbered 5991, 5992, 5993, 5995, 5996, and 5997) are shown in Figure 1. These small timber bridges exist in topography that is considered level terrain with the existing highway grades generally ranging from 0-3%. The bridge sites are in a rural, agricultural area with no surrounding developments. The timber structures were originally constructed in the 1930’s and are in fair to poor condition. The bridges act as a crossing for continually flowing streams or as underpasses for livestock. While the primary intent of the geotechnical investigation is to estimate subsurface conditions for proposed new bridges or box culverts, the project presented the opportunity to collect data for identifying potential correlations between engineering and geophysical parameters of the materials.
Static and Dynamic Mechanical Properties of Rock at Elevated Temperature
Authors: Mitra A. , Djordjevic O. , Thombare A. , Govindarajan S. , Gokaraju D. , Aldin M. , Patterson R. , Simone A. 
Published: September 2022

ABSTRACT:
Knowledge of mechanical properties of subsurface at elevated temperature is crucial to understand a range of processes in the earth’s crust and in building geomechanical models to assist in operating geothermal systems, nuclear waste repository, CO2 sequestration and hydrocarbon extraction. Although there exists sufficient literature reporting measurement of static mechanical properties on a range of rock types at elevated temperature, reported values for ultrasonic velocities are extremely limited. This in turn presents a challenge for the dynamic-to-static conversion of mechanical properties, a pivotal step in building geomechanical model. This paper presents the results of a laboratory study utilizing Berea and Upper Gray Berea sandstone and mudstone samples from a producing US reservoir at 75°C. A decrease in both P and S wave velocity with temperature is observed in a Berea sample. A decrease in static Young’s modulus is observed in mudstone samples from two clay-rich reservoir intervals with one of the reservoir intervals demonstrating significant static and dynamic anisotropy. Additionally, the samples from both intervals mimicked the response of Berea for dynamic mechanical properties under constant hydrostatic stress. This study is intended to provide better representative inputs for improving the accuracy of subsurface characterization and geomechanical models for aforementioned applications.

1. INTRODUCTION
The knowledge of mechanical properties of rock at elevated temperature is crucial to understand and model a number of processes in the earth’s crust (Heuze, 1983). Such information also adds value in designing high-level nuclear waste disposal (Klett, 1974). In the oilfields, high-temperature operating environment is frequently encountered in deepwater operations (DeBruijn, 2008) and heavy oil reservoirs (Curtis, 2002). Chen and Ewy (2005), for example, observed that heating the wellbore increases both the collapse and fracture pressure gradient. For geothermal energy recovery, high temperature is a common challenge for drilling (Meng et al., 2019). Finally, for CCUS, CO2 need to be injected beyond a certain temperature to ensure supercritical condition. All of these requires a deep understanding of mechanical properties of rock at elevated temperature.