bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of Geomechanical Properties of Fault Damage Zones Based on Numerical Modeling
Authors: Dias F. C. , Quevedo R. , Roehl D. , Carvalho B. 
Published: August 2024

ABSTRACT:
Fault zones are generally made of highly deformed rocks composed of a core surrounded by a damage zone. The core is usually formed of an impermeable consolidated material responsible for reservoir compartmentalization. However, the complex architecture of damage zones induces a substantial variability of their properties that can significantly influence fluid flow and geomechanical behavior of oil and gas fields. Therefore, characterizing damage zone properties is relevant during reservoir development, production, and management. Many studies have been carried out to characterize and estimate the structural and hydraulic properties of fault damage zones. Still, relatively few of these studies have aimed at assessing their elastic, strength, and compaction properties. The reason for that is the difficulty in sampling fault damage zones for laboratory testing owing to intense fracturing and poor consolidation. In addition, the sampling protocols face the classical question of the scale effect on the properties of fault rocks. This study uses a numerical methodology to estimate rock properties of fault damage zones through geomechanical modeling based on the finite element method combined with elastoplastic models and softening/hardening laws. The obtained properties can be adopted in further simulations to represent fault damage zones better.

1. INTRODUCTION
Most geologists recognize that faults include subsidiary structures in a region that covers both brittle discontinuities and ductile shear plastic deformation zones (Fossen, 2016). This region, known as the fault zone, consists of two structural domains: the fault core, defined by a central slip surface, and the surrounding volume, named the damage zone. In general, the fault core is a low-permeability zone with a width in the order of millimeters. On the other hand, depending on host rock lithology and fault displacements, damage zone widths can reach dimensions in the order of kilometers. Most damage zones in subsurface faults are characterized by a set of deformation bands and fracture networks, triggering a region with properties significantly different from the undeformed host rock or protolith (Caine et al., 1996; Paul et al., 2007; Hennings et al., 2012; Choi et al., 2016).
For example, permeabilities in the damage zone can be several orders of magnitude higher than those in the protolith during fracturing, while Young's modulus values are usually lower (Cappa, 2009). Some authors have reported that permeability and Young's modulus of fault damage zones can vary in ranges from 1 · 10-14 to 10-16 m2 and 10 to 50 GPa, respectively (Faulkner & Rutter, 2001; Zhang et al., 2008; Cappa & Rutqvist, 2011; Qu & Tveranger, 2016; Treffeisen & Henk, 2020). In addition, frictional properties can be quite different between the host rock and the fault damage zone, with values reduced by up to 65% in the latter (Di Toro et al., 2011).
Laser-Induced Rock Breakage (LIRB) Technology in Mining Engineering - A Review
Authors: Madavi R. P. , Mitra R. , Diwakar P. 
Published: August 2024

ABSTRACT:
Mining operations have long relied on conventional methods of rock fragmentation, such as drilling and blasting, for resource extraction. However, as the mining industry faces increasing demands for efficiency, safety, and sustainability, innovative technologies like laser-induced rock breakage (LIRB) have emerged as promising alternatives. LIRB, a cutting-edge technique, employs high-energy lasers to fracture rocks without physical contact, avoiding the use of explosives. This paper provides a comprehensive review, begins by delving into the fundamental principles of LIRB, discussing the various types of lasers used, and highlights the merits of LIRB in terms of safety and environmental impact. Despite the promising advantages of LIRB, this review also addresses the challenges and limitations that researchers and engineers face. These challenges encompass heat management, limited penetration depth, complexity of laser systems, and the development of cost-effective and scalable LIRB systems. Additionally, the need for a thorough understanding of rock properties and behavior is emphasized, as it is critical for achieving successful LIRB outcomes.

1. INTRODUCTION
The first working laser was built by Theodore H. Maiman in 1960 at Hughes Research Laboratories (Bromberg, 1988). Maiman's laser used a synthetic ruby crystal to produce red laser light. This invention marked the beginning of the era of lasers and their widespread applications in various fields. One of these fields was rock breakage and the first experiment in this field was performed in 1969 by United Aircraft Research Laboratories under the Department of Transportation. In this study, the weakening of hard rock by low-power-density laser was considered feasible but not economically viable for tunnel boring machines (TBMs) (Farra, 1969). However, using a high-power-density laser, the laser beam can penetrate the rock which allows the removal of a greater amount of rock (Carstens & Brown, 1971). Various studies by researchers showed that laser-assisted rock cutting has great potential in rock excavation fields (Carstens & Brown, 1971; Jurewicz, 1976; Rui and Zhao, 2021). Apart from traditional drilling and blasting, various other technologies such as thermal rock fracturing (Geller, 1970), high-pressure water jet (Vijay et al., 1993), microwave (Okada et al., 1975), electrical (Andres, 1995), and Soundless Chemical Demolition Agents (SCDAs) (Habib et al., 2022) have been developed for improving rock breakage process.
Estimation of Tunnel Project Completion Time by Combining the CSM2020 Discrete Event Simulation Model with Decision Aid in Tunneling (DAT)
Authors: Khetwal A. , Rostami J. , Einstein H. 
Published: August 2024

ABSTRACT:
The decision-making process regarding the uncertainty in the project plan, alignment alternatives, and other project aspects can be accounted for using the Decision Aids in Tunneling (DAT) tool. One of the important input parameters in the DAT is the advance rate, and its accurate estimation can significantly improve the accuracy of the DAT. The advance rate comprises the estimation of the rate of penetration and machine utilization. A few models have been proposed to estimate utilization with different levels of accuracy. The CSM2020, which is a discrete event simulation-based model, has proven to offer a promising estimation of TBM utilization as it incorporates uncertainties in various tunneling activities. The model more reliably allows for the determination of the delays during the tunneling and hence more reliable machine utilization for a given machine type, geological settings, and operational conditions. In the present study, project data were analyzed, and utilization values were estimated using the CSM2020 model and used as input in the DAT to estimate overall anticipated machine performance in a given project. The results include the average completion time that was compared with the actual site data. The accuracy in the completion time shows that a combination of CSM2020 and DAT can be considered to be an effective approach to consider the uncertainties in the various tunnel operations, thereby offering a more accurate and reasonable estimation of completion time for mechanized tunnels.

1. INTRODUCTION AND BACKGROUND
The modern world has given society marvelous underground structures and the comfort of traveling through railways, metros, and road tunnels. These underground spaces provide infrastructure that is difficult or impossible to construct above ground or whose presence above ground is unacceptable, undesirable or simply not feasible. They have the fundamental characteristics of protecting against almost all-natural threats (Goel et al., 2012). With the increasing world population, there is a necessity for sustainable development that does not compromise the future generations' correlations while meeting the present needs, and tunnels are considered a significant contributor to this. They have proven to be an efficient infrastructure in conveying freshwater, disposing of waste products, as a safe and fast conveyance route, functional during extreme weather conditions, and for bulk storage of liquids and gas.
An Assessment of Hydraulic Fracture and Geomechanical Properties on the Compaction and the Productivity of Marcellus Shale Horizontal Wells
Authors: El Sgher Mohamed , Aminian Kashy , Ameri Samuel 
Published: August 2024

ABSTRACT:
Declining pore pressure, with reservoir depletion, increases the net stress leading to compaction of the Marcellus shale damaging the formation and hydraulic fracture properties. To accurately predict gas production as net stress increases, geomechanical and fluid flow simulations are required. By analyzing data from Marcellus Shale Energy and Environment Laboratory sites, researchers were able to investigate the impact of shale compaction on gas production. The study was focused on how shale mechanical and fracture properties, as well as operating conditions, influence the productivity of horizontal Marcellus Shale wells with multi-stage fractures. Simulated model results showed that including the compaction in the model resulted in more accurate prediction of production from horizontal wells with multiple hydraulic fracture stages in the Marcellus shale. Young's modulus was observed to have a greater impact on the geomechanical factors and the production performance than for Poisson's ratio. Furthermore, Due to the high gas production rate during early production, compaction has a more dramatic impact which diminishes as production continues.

1. INTRODUCTION
The Marcellus Shale is the largest shale play in the United States, covering a vast geological area of 95,000 square miles. This shale formation, known for holding the largest natural gas deposits in the U.S., is predominantly found in the Permian Basin. The Marcellus Shale, situated in the Appalachian Basin, stands out as the most prominent natural gas-producing play in the country and spans across six states: New York, Pennsylvania, Ohio, West Virginia, Maryland, and Virginia. Characterized as an abundant fine-grained sedimentary rock formed through the compaction of silt and clay-size mineral particles, the Marcellus Shale exhibits the ability to fold into thin layers. Being over 400 million years old, this formation ranks among the largest nationwide and is a top producer of natural gas in the U.S. With the implementation of modern exploration techniques like hydraulic fracturing and horizontal drilling, the Marcellus Shale is estimated to hold around 400 trillion cubic feet of gas, attracting significant attention from the oil and gas industry in the U.S.
Integrating Rock Physics Templates for Enhanced Seismic Interpretation: A Comprehensive Analysis of Influencing Factors on Frequency-Dependent Velocity of Tight Carbonate Formations
Authors: Malki Mohamed L. , Allam Lotfi , Mellal Ilyas , Latrach Abdeldjalil , Rasouli Vamegh , Larbi Anis , Chellal Hichem 
Published: August 2024

ABSTRACT:
This study conducts an in-depth rock physics analysis of the Bakken and Three Forks formations within the Williston Basin, emphasizing the role of fluid types, saturation levels, pore structure, and frequency on defining rock properties. The objective is to enhance seismic interpretation and reservoir characterization by developing rock physics templates (RPTs) for these specific formations. We explore how pore structure heterogeneity influences velocity sensitivity over a broad frequency range and varied fluid types. By integrating both Gassmann and Biot theories for fluid substitution and considering frequency-dependent velocity via Geertsma-Smit approximation, the study models fluid properties, and their interaction with the rock matrix, supported by case studies from the Bakken formation. Findings from this study reveal that gas-water systems are more frequency-dependent compared to oil-water systems. Moreover, the frequency-dependent velocity modeling revealed that combining pore structure with varying porosity and permeability levels can significantly influence the velocity-frequency relationship. The research further delineates the complex interplay between the Vp/Vs ratio and acoustic impedance, pore morphology, and fluid saturation. Notably, crack-like pores are linked with larger Vp/Vs ratios, while interparticle and vuggy pores show a more homogeneous stiffness distribution. The proposal of geology-dependent RPTs emphasize the need to consider lithological and diagenetic variations for accurate seismic interpretations.

1. INTRODUCTION
The detection of fluids through seismic reflections is a critical aspect of hydrocarbon exploration, marked by distinct indicators such as bright spots, dim outs, phase reversals, and flat spots (Smith & Gidlow, 1987; Smith & Sutherland, 1996). In seismic forward modeling, accurate fluid characterization is essential, significantly influencing Amplitude Versus Offset (AVO) interpretation (Mughal & Akhter, 2020; Smith et al., 2003). This is especially challenging for gas due to its compressibility and lower density compared to other fluids, which can lead to abnormal frequency-dependent velocity dispersion and attenuation (Malki et al., 2022a). The complexity is further heightened in carbonate reservoirs compared to siliciclastics, due to their heterogeneous pore structures, which intricately affect the velocity response to various fluid types and frequency amplitudes (Anselmetti & Eberli, 1999; Malki et al., 2023a). This sensitivity is pronounced in fractured reservoirs, where the coexistence of diverse pore structures necessitates sophisticated rock physics modeling to accurately predict P- (Vp) and S-wave (Vs) velocities under varying saturation levels and frequency ranges (Saberi, 2010).
Permeability of Serpentinized Harzburgite and its Implications on Mineral Carbon Storage
Authors: Asem Pouyan , Nguyen Anh , Bažant Zdenek P. , Matter Juerg , Labuz Joseph F. 
Published: August 2024

ABSTRACT:
Storage of anthropogenic CO2 as permanent carbonate minerals has emerged as a promising method for control of carbon dioxide. One approach consists of injecting low-pH, CO2-rich water in ultramafic rock that serves as a buffering medium. Accordingly, the rock dissolution will increase the solution pH such that carbonate minerals can precipitate. The permeability of the rock matrix, however, plays an important role in the buffering (dissolution) process and controls chemical reaction rates. Using X-ray diffraction spectroscopy (XRD), we analyzed the composition of the (i) vein filling material in a serpentinized harzburgite, and (ii) matrix adjacent to the vein. The XRD analysis showed that hydrated carbonates mineralized in the vein as well as the intact matrix adjacent to the surface. Permeability of the serpentinized rock matrix adjacent to the vein surface was then measured using the pulse decay approach. It is shown that a permeability on the order of 10-21 m2 and rock matrix with less than 25% serpentine minerals allowed for fixing CO2 as thermodynamically stable, hydrated carbonate minerals in the matrix.

1. INTRODUCTION
Harzburgites of the upper mantle sequence in most ophiolites are partially to fully serpentinized (O'Hanley 1996; Mevel 2003; Kelemen and Matter 2008; Boudier et al. 2010). The hydration and carbonation of facies that have undergone less serpentinization and hence are rich in olivine and pyroxene can be described by coupled dissolution-precipitation reactions:
(equation)
(equation)
Most accessible parts in ultramafic formations of the upper mantle in ophiolites, however, are pervasively serpentinized and hence contain considerable amounts of serpentine group minerals (e.g. lizardite, chrysotile, antigorite). The hydration and carbonation of serpentinized harzburgites include the dissolution of serpentine minerals (Luce 1969):
(equation)
followed by carbonation reactions where the liberated magnesium ions will bind with carbonate ions to form magnesite:
(equation)
The permeability of the rock matrix, however, plays an important role in the dissolution and buffering processes, controls chemical reaction rates and the extent of carbonation and hydration processes. Using X-ray diffraction spectroscopy (XRD), we analyzed the composition of the (i) vein filling material in a serpentinized harzburgite, and (ii) matrix adjacent to the fracture surface. The XRD analysis showed that hydrated carbonates mineralized in the vein as well as the intact matrix adjacent to the vein surface. Permeability of the serpentinized rock matrix adjacent to the vein surface was then measured using the pulse decay approach. It is shown that a permeability of the order of 10-21 m2 and rock matrix with less than 25% serpentine minerals allowed for fixing CO2 as thermodynamically stable, hydrated carbonate minerals in the matrix.
Seismic Source Characterization with Distributed Acoustic Sensing
Authors: Li Jiaxuan , Zhu Weiqiang , Biondi Ettore , Zhan Zhongwen 
Published: August 2024

ABSTRACT:
The emerging distributed acoustic sensing (DAS) technology can convert a pre-existing telecommunication fiber cable of tens of kilometers in length into a dense seismic array of thousands of recording channels. By measuring the laser phase change of the Rayleigh backscattering from intrinsic impurities in the fiber, a DAS system can infer the longitudinal strain or strain rate every few meters along the fiber at a frequency of hundreds of Hertz. DAS unprecedented temporal and spatial resolution makes it a promising technology for monitoring and characterizing earthquake source properties. Yet, challenges remain in leveraging this new technology due to large data volumes and the inadequacy of conventional algorithms applied to dense single-component DAS recordings. Here, we will showcase a series of research progresses in leveraging DAS for analyzing high-resolution earthquake source properties, including seismic phase picking, earthquake relocation, focal mechanism inversion, and high-resolution rupture imaging. We first introduce PhaseNet-DAS, a convolutional neural network model, for automated earthquake detection and seismic phase identification from DAS recordings. Our scalable cross-correlation framework, called CCTorch, then robustly measures differential phase traveltimes and relative polarities between picked seismic events. Furthermore, we have devised a matrix-free adjoint solver that can perform double-difference relocation using thousands of DAS channels. We have also developed a data-driven method that can reliably invert absolute first-arrival polarities on DAS, which can tightly constrain the nodal plane orientations and are critical for inverting high-resolution focal mechanisms. We have successfully applied all of these methods to several DAS arrays in California. Finally, we will showcase the back-projection rupture imaging results for the Mw6 crustal earthquake that occurred in Antelope Valley, CA in 2021. We will show that the high-resolution rupture imaging enabled by the dense DAS array can reveal the detailed underlying rupture processes and physical mechanisms at a much lower cost compared to the conventional seismic network. These successful research progresses underscore the potential of DAS as the next-generation seismic monitoring tool, that can significantly enhance and complement existing seismic networks. With the extensive existing and proposed network of onshore/offshore telecommunication fiber cables, DAS would provide critical datasets for systematically investigating the detailed seismic source properties.
Foam-Based Hydraulic Fracturing from Lab to Field Applications: A Brief Review
Authors: Abdelaal Ahmed , Aljawad Murtada Saleh , Al-Shehri Dhafer 
Published: August 2024

ABSTRACT:
Hydraulic fracturing, as described in petroleum literature, involves injecting fluids under high pressure to fracture formations in a controlled manner, aiming to enhance productivity and/or address near wellbore damage. Traditional water-based fracturing fluids have been widely used due to their cost-effectiveness and simplicity. However, they pose challenges such as formation water sensitivity, blockages, difficulties in transporting proppants, water availability concerns, and issues with cleaning up low-pressure reservoirs. These challenges have spurred research into alternative solutions. Foam-based fracturing technology has emerged as a promising alternative to water-based fracturing due to its minimal or zero water usage. By reducing water usage, foam fracturing minimizes near wellbore damage, lowers the risk of permeability impairment, and addresses environmental worries associated with excessive wastewater. Additionally, foam fracturing appears particularly suitable for shale gas reservoirs. This paper offers a review of foam-based fracturing fluids, delving into both lab studies and practical applications. The paper analyzes the advantages and limitations of foam fracturing compared to water fracturing. Finally, the outcomes of foam fracturing in numerous oil and gas fields are summarized. Experimental and field application results demonstrate that foam fluids have the potential to enhance hydraulic fracturing both technically and economically. The paper also identifies existing challenges and knowledge gaps, guiding future research directions in this area.

1. INTRODUCTION
Stimulation techniques were developed to enhance the productivity of wells in different ways. Technically, hydraulic fracturing can be used to bypass the damaged zones or/and to provide a high conductive pathway in very low permeability reservoirs such as shale gas (commonly less than 1 mD) (Gu & Mohanty, 2014). Economically, hydraulic fracturing increases the well productivity and makes the exploitation of unconventional reservoirs feasible. Recently, 50% of liquid petroleum and 75% of gas production in United States came from tight reservoirs (L. Wang et al., 2017). Multi-stage hydraulic fracturing combined with horizontal drilling paved the road for unconventional resources to be produced economically (Vidic et al., 2013).
Hydraulic fracturing is the most used stimulation technique for hydrocarbon reservoirs. Hydraulic fracturing creates artificial fractures in targeted reservoir (especially very low permeability) by injecting pre-designed fluids at high pressure into the formation through a well. Proppant is mixed with fracture fluids to keep the fractures open after fracture closure. The used fluids are produced after the job (clean-up) and the fractures provide a conductive pathway for the hydrocarbons.