bluuebunny/crossref_metadata_2025_split huggingface dataset:
Current Activities at the Utah Frontier Observatory for Research in Geothermal Energy (FORGE): A Laboratory for Characterizing, Creating and Sustaining Enhanced Geothermal Systems
Authors: Moore Joseph , McLennan John , Pankow Kristine , Finnila Aleta , Dyer Ben , Karvounis Dimitrios , Bethmann Falko , Podgorney Robert , Rutledge James , Meir Peter , Xing Pengju , Jones Clay , Barker Benjamin , Simmons Stuart , Damjanac Branko 
Published: September 2023

ABSTRACT
Enhanced Geothermal Systems (EGS) offer the best potential for meeting the U.S. Department of Energy's objective of 90,000 MWe by 2050. The Utah Frontier Observatory for Research in Geothermal Energy (FORGE) was established to de-risk tools and technologies required for commercialization of EGS. Six deep wells have been drilled into the low permeability granitic and metamorphic rocks hosting the reservoir. One is highly deviated and will serve as the injection well during reservoir creation. The deepest well, drilled to a depth of (2,896 m (9500 ft) has an estimated bottom-hole temperature of 241°C (465°F). Injection tests indicate a minimum horizontal stress gradient of 16.74 kPa/m (0.74 psi/ft) and a permeability of ∼20 micro-Darcies. A three-stage stimulation of the injection well was performed in April 2022. In the first stage, slickwater was pumped into the open hole section of the well at 50 bpm (7.95 m3/min). The second and third stages were performed in the cased portion of the well using slickwater and a viscosified fluid. Flow rates of 35 bpm (5.56 m3/min) were achieved in both zones. Microseismic events recorded during the stimulation ranged from −2.3 to +0.5 Mw. Drilling of the production well is planned for 2023.

INTRODUCTION
Enhanced Geothermal Systems (EGS) offers the greatest potential for meeting the U.S. Department of Energy's (DOE) goals of 90,000 MWe by 2050 and reducing the cost of electricity by 90% to $45 per MW-hour. Since the late 1970s, more than a dozen EGS projects have been conducted throughout the world in an effort to create geothermal reservoirs where none exist naturally. None of the projects have achieved commercial scale levels of production.
The Utah Frontier Observatory for Research in Geothermal Energy (FORGE) was developed to de-risk and test techniques for creating, sustaining and monitoring EGS reservoirs. The ultimate goal of the Utah FORGE field-scale project is to demonstrate to the public, stakeholders and the energy industry that EGS technologies have the potential to contribute significantly to future power generation (Moore et al., 2020, 2021).
A Graphical Analysis-Based Elastoplastic Solution for Undrained Wellbore Drilling Problem in Hoek-Brown Rock Formation
Authors: Abu-Dayyeh H. , Wang X. , Chen S. L. , Han Y. H. , Abousleiman Y. N. 
Published: September 2023

ABSTRACT
An analytical solution is developed for evaluating the stability of an impermeable wellbore in rock formation that obeys Hoek-Brown failure criterion in a hydrostatic stress field. The solution is derived in the framework of the graphical analysis method recently developed by Chen and Abousleiman (2022). The graphical analysis approach can effectively overcome two essential limitations that exist in the implementation of the Hoek-Brown model in the current literature, i.e., first, the mathematical difficulties involved in the treatment of corner singularity of the yield surface; and second, the intermediacy assumption for the axial stress with respect to other stresses. The graph-based solution procedure follows two steps: (1) to geometrically track the stress path trajectory laid out in the deviatoric stress plane; and (2) to formulate the constitutive equations and the radial equilibrium equation. It is found that the effective stress path corresponding to the borehole drilling process is composed of piecewise curved and straight lines in the deviatoric stress plane; it eventually terminates in the major sextant with the Lode angle θ ranging from π/2 to 2π/3 or, on the line of θ = π/2, depending on the mechanical properties of the rock. The analytical solution obtained is a rigorous and complete one for the borehole drilling problem.

INTRODUCTION
Wellbore instability is a significant subject in the application of rock mechanics in the oil and gas industry (Santarelli et al, 1986; Yu, 2000). The study and analysis of stresses around wellbores is crucial in the reduction of monetary losses associated with this problem (Yu, 2000; Chen, 2012). Choosing the right model is essential for accurately predicting mud pressure, calculating wellbore stresses, and ensuring safe wellbore drilling (Zoback, 2007; Yu, 2000). Consequently, this can help mitigate two main problems that cause wellbore instability: borehole collapse and borehole fracturing (Santarelli et al, 1986). Estimation of the critical mud pressure is obtained by choosing a failure criterion and using a constitutive model to estimate the stresses induced around the wellbore (Al-Ajmi, 2006).
Machine Learning Modeling of Saudi Arabian basalt/CO2/brine Wettability Prediction: Implications for CO2 Geo-Storage
Authors: Tariq Zeeshan , Ali Muhammad , Yan Bicheng , Sun Shuyu , Hoteit Hussein 
Published: September 2023

ABSTRACT
CO2 wettability and the reservoir rock-fluid interfacial interactions are crucial parameters that regulates the successful CO2 geological sequestration. This study implemented the feed-forward neural network to model the wettability behavior of Saudi Arabian (SA) basaltic rocks in a ternary system of basaltic rocks, CO2, and brine under different operating conditions. To gain higher accuracy of the machine learning models, a sufficient dataset was utilized that was recorded by conducting a large number of laboratory experiments under a realistic pressure range, 0 – 25 MPa and the temperatures range, 298 – 343 K. Different graphical exploratory data analysis techniques, such as heatmaps, violin plots, and pair plots were used to analyze the experimental dataset. The machine learning models were trained to predict the receding and advancing contact angles of SA basalt/CO2/brine systems. Both statistical evaluation and graphical analyses were performed to show the reliability and performance of the developed models. The results showed that the implemented ML model accurately predicted the wettability behavior under various operating conditions.

INTRODUCTION
Geological formations offer a promising solution to reduce global warming and achieve a low-CO2 economy by injecting carbon dioxide (CO2) into them (Alam et al., 2014; Bethke, 2007; Egermann et al., 2005, 2005; Iglauer et al., 2015; Wang et al., 1998). Saudi Arabia, a significant hydrocarbon-producing country, possesses numerous existing infrastructures and transportation pipelines suitable for natural gas storage, which could be utilized for large-scale CO2 storage in depleted hydrocarbon reservoirs, saline aquifers, and salt caverns. Moreover, sedimentary formations like shales, tight sandstone or carbonates, and igneous rocks such as basalts have recently emerged as potential formations to investigate for CO2 storage (Yan et al., 2022c).
Dark-colored, fine-grained igneous rocks called basalts consist mainly of pyroxene, plagioclase, and olivine. They are more abundant and accessible than shales, and the Cenozoic volcanic rocks in Saudi Arabia are one of the largest areas of alkali olivine basalt worldwide, covering nearly 90,000 km2. Carbon mineralization is the primary method of CO2 storage in reactive rocks like basalt, and research has shown that basalt can be suitable for CO2 storage through this method, or residual trapping if the basalt formation is capped. Basalt is distributed worldwide with a favorable mineral composition, significant thickness, and good vesicular texture. In contrast to silica minerals in sedimentary formations, CO2 injection into volcanic rocks like basalt can swiftly initiate carbon mineralization and mineral trapping, as evidenced by successful pilot project trials conducted in Washington State (USA) and Iceland, which showed that most of the injected CO2 was mineralized in less than two years.
Variational Interface Physics Informed Neural Networks (VI-PINNs) for Heterogeneous Subsurface Systems
Authors: Sarma A. K. , Annavarapu C. , Roy P. , Jagannathan S. , Valiveti D. M. 
Published: September 2023

ABSTRACT
This study presents a novel approach to Physics Informed Neural Networks (PINNs) called Variational Interface PINNs (VI-PINNs) for modeling physical systems with material interfaces. In conventional PINNs, a loss functional obtained from the residual of the strong form of governing equations is minimized to estimate the variable of interest. By contrast, the presented approach relies on minimizing the potential energy functional of a physical system using artificial neural networks. Firstly, we present appropriate modifications to the neural network architecture so that material interfaces can be captured effectively in a variational framework using neural networks. Secondly, we incorporate the interface coupling conditions in the energy functionals to be minimized using VI-PINNs. Thirdly, we examine several numerical integration techniques and compare their accuracy and cost to evaluate the Lagrangians in the VI-PINNs framework. Finally, we discuss a variationally consistent penalty approach to enforce boundary and interface conditions better. Several benchmark 1D and 2D examples are solved using the proposed method and conventional PINNs. Their performances are then compared in terms of cost and accuracy, and their relative strengths and weaknesses are identified.

INTRODUCTION
Subsurface systems are often characterized by a high degree of heterogeneity. Heterogeneities in the subsurface may arise from the natural layering of the earth's crust or naturally occurring faults. In addition, stimulation methods such as hydraulic fracturing also contribute to its heterogeneous character. The heterogeneity of these systems can significantly impact the behavior and movement of fluids, such as water, oil, and gas, within the subsurface. As a result, the study and understanding of heterogeneous subsurface systems are critical for a wide range of industries, including petroleum engineering, geotechnical engineering, hydrology, and environmental science, where accurate predictions of fluid behavior and movement are essential.
Traditionally, several high-fidelity physics-based numerical modeling techniques, including the Finite Element Method (FEM), have been utilized for modeling subsurface systems. These methods involve using a mesh or grid to approximate the system and necessitate the proper meshing of the subsurface into non-overlapping elements. However, generating meshes that conform to the complex geometrical shapes that represent the various subsurface features of interest is non-trivial. This pre-processing step, which involves generating meshes that effectively depict subsurface features, imposes a considerable computational burden and requires frequent analyst intervention (Annavarapu (2013)).
Impact of Deformability of Karstified Features on Production Curves: A Case Study of a Typical Brazilian Pre-Salt Carbonate Reservoir
Authors: Maria A. L. M. , Machado M. V. B. , Falcão F. O. L. , da S. Carvalho M. 
Published: September 2023

ABSTRACT
More than 60% of Brazilian oil production comes from carbonate reservoirs. These reservoirs have become more significant in the Brazilian energy matrix since the discovery of the Pre-Salt layer in Santos Basin, which accounts for more than half of PETROBRAS’oil production nowadays. Brazilian Pre-Salt fractured and karstified carbonate reservoir characterization is one of the primary issues when considering the Reservoir Geomechanics discipline within PETROBRAS. For instance, the compressibility estimate method for karstified media remains challenging. In this work, the (Dobrynin, 1970) approach was used to assess the compressibility of the karst features. Due to its lower computational cost, the pseudo-coupling method was used to simulate geomechanical effects in flow simulation based on these compressibilities estimated values. The results permit the estimate of its impact on production forecast and history matching curves. The general behavior of karst compressibility as a function of porosity is one of the critical findings of this study. The magnitude of karst compressibility for a typical Pre-Salt reservoir is another essential result that permits specialists in reservoir simulation and geomechanical modeling to enhance the accuracy of production forecast and deformation estimate for karstified reservoirs.

INTRODUCTION
Currently, more than 60% of Brazil's oil production is derived from carbonate reservoirs. Due to the discovery of the Pre-Salt layer, which accounts for more than half of PETROBRAS’oil production, these reservoirs have risen to prominence in Brazil's energy matrix. Fig.1 represents the exploration and prodution maps of Pre-Salt fields.
Due to the heterogeneities of this type of reservoir, exploration and production present numerous obstacles. Regarding the development and production of a typical Brazilian Pre-Salt field, one of the most challenging aspects of the Reservoir Geomechanics discipline is the characterization of fracture and karst systems.
The evolution of the characterization process of these systems, especially when considering geomechanical effects and fluid behavior is directly proportional to the accuracy of the production forecast curves of carbonate reservoirs. Determining the parameters required by numerical simulators for reservoir studies and geomechanical analyses is part of characterizing a reservoir. Although compressibility of pores is an essential parameter for flow simulation and the unique input that effectively represents the geomechanical effects, it is kept constant during the whole reservoir flow simulation.
Phase-Field Modeling of Hydraulic Fracturing Under Heterogeneities And/Or Layering of Rock Properties and In-Situ Stress
Authors: Fei F. , Costa A. , Dolbow J. E. , Settgast R. R. , Cusini M. 
Published: September 2023

ABSTRACT
Hydraulic fracturing is a process of creating artificial fractures to enhance the hydraulic conductivity of nearly impermeable rock masses, enabling an economic development of many subsurface energy systems. Due to heterogeneities and layering of rock properties and in-situ stress, hydraulic fracture propagation commonly involves highly complex patterns. To investigate the effects of material heterogeneities and layered rock structure on hydraulic fracturing, numerical modeling usually plays a central role. Most existing numerical methods, however, face a formidable challenge in handling fracture propagation with complex geometries, which can potentially occur in heterogeneous and layered rock formations. A remedy for this challenge is to use the phase-field method. Basically, the phase-field method models the fracture propagation as evolution of a diffusely distributed damage variable, so it allows ones to model hydraulic fracture propagation without explicitly tracking the crack geometries. In this study, we adopt a recently developed phase-field approach to hydraulic fracturing to numerically investigate the effects of heterogeneities and layered structure on near-wellbore hydraulic fracture propagation. Compared with existing phase-field models, this new phase-field model features its capability to capture a rock strength that is independent of the phase-field regularization length. This capability thus allows ones to simulate hydraulic fracture nucleation and propagation in a heterogeneous and layered domain with a uniform regularization length. We then perform a series of hydraulic fracturing simulations with layering of in-situ stress and heterogeneous critical fracture energy. We believe the outcome of this numerical study can improve our understanding of the mechanisms behind the hydraulic fracture propagation in heterogeneous and layered rock formations.

INTRODUCTION
For many subsurface applications, such as oil and gas production from tight reservoir and enhanced geothermal systems (EGS), it is necessary to hydraulically fracture the rock to enhance its permeability and favor fluid circulation. The fractures are generated by injecting a high-pressure fluid (e.g., water). The characteristics of the generated fractures determine the efficiency of the stimulation treatment and possible hazards associated with the fracturing process. The propagation direction, the geometry, and the extent of the hydraulically generated fractures are greatly influenced by the in-situ stress conditions and the heterogeneity of rock properties (Yang et al., 2004; Xu et al., 2019; Zoback et al., 2022). Therefore, it is crucial to develop numerical tools that can reliably and efficiently model hydraulic fracture nucleation and propagation in heterogeneous porous media.
Distinct Element Analysis of Various Structural Element Responses for Coal Rib Support Simulation
Authors: Kirmaci A. , Guner D. , Karadeniz K. , Sherizadeh T. 
Published: September 2023

ABSTRACT
Understanding the bolt responses for the efficacy of bolt performance during coal rib support applications plays a key role in controlling the stability of underground coal mine openings. Conducting pull-out tests is imperative to gain a better understanding of these responses. Field conditions such as block volume and degree of cleating may significantly impact bolt performance. These field conditions can be efficiently implemented in numerical modeling approaches, and selecting a proper structural element type for these numerical studies is crucial. This study developed a pull-out test model and compared the performance of structural elements as support members in the coal rib model using 3DEC, a three-dimensional distinct element-based numerical modeling code. This study covered commonly utilized cable, pile, and hybrid structural elements in rib models with explicitly introduced face cleats. The bolt response of numerical models was calibrated with the field data showing the load-displacement response of a pull-out test. Comparing the rib models with these structural elements showed that hybrid structural elements demonstrated better agreement with the field observation as they can simulate the reaction to shearing along the discontinuities by inducing bending stresses. The impact of support density on rib stability is also presented in this study.

INTRODUCTION
The fact that injuries and fatalities linked to rib failure persist in underground coal mines, despite measures taken to ensure rib stability emphasizes the urgent need to develop and validate support systems that can effectively reduce coal rib failures. Currently, there is no standard practice for coal rib supports that can effectively address the diverse range of conditions encountered in coal mines across the United States (Guner et al., 2023). That leaves mine operators with no option but to rely on trial-and-error or industrial legacy practices. The severity of rib instabilities as a ground control hazard in underground coal mines is highlighted by the average annual fatality rate caused by coal rib failures, which remained at 1.6 between 2009 and 2022, as reported by MSHA (2022). Although coal rib failures pose a significant risk to the safety of the miners, there is limited information on these events and how rib support can mitigate them. Therefore, conducting studies to analyze the current rib support strategies and reduce injuries and fatalities resulting from rib failures in the coal mining industry is essential.
Explosion Resistance of Reinforced Concrete Refuge Alternative Wall Under Certain Abutment Loading
Authors: Karadeniz K. E. , Guner D. , Sherizadeh T. 
Published: September 2023

ABSTRACT
Build-in-place (BIP) refuge alternatives (RAs) are used to provide safe havens for miners unable to escape their working area after an accident like an explosion. These underground infrastructures are built over time in various locations and might expose to mining-induced stresses. The convergences related to these stress redistributions around the mine openings might change their structural integrity and, subsequently, the explosion resistivity. Studying the effect of increasing vertical load like abutment stress on such underground mine stopping for the explosion resistance is difficult because repetitive explosion experiments on these structures are perilous and challenging. This study uses two case studies to simulate the real-time monitored abutment loading condition and the explosion testing on such steel-reinforced underground structures. A BIP RA design's performance and failure analysis were evaluated under these two conditions using 3DEC, a three-dimensional distinct element solver. This study aims to reveal the effects of vertical convergence due to panel extraction on the explosion resistance of such reinforced concrete walls. The model results demonstrate that the abutment loaded stopping shows higher deformation during and after the explosion than the models without excessive vertical loads. The stopping has high displacement levels at the top of the structure, resulting in the highest deformation zones being extremely distinctive.

INTRODUCTION
Mine explosions are among the most concerning hazards associated with underground coal mining, as a single gas explosion can result in injuries and fatalities among miners. In 2006, three separate disasters - the Sago Mine Explosion in West Virginia, the Aracoma Alma Mine Fire in West Virginia, and the Darby No.1 Mine Explosion in Kentucky - claimed a total of 47 lives in the United States (Yantek and Schall, 2017). This tragic outcome led to the Mine Safety and Health Administration (MSHA) introducing more rigorous regulations and served as the catalyst for the creation of the Miner Act of 2006 (Fasouletos, 2007; Mitchell, 2008; Zipf et al., 2009; Karadeniz et al., 2022). The regulations stipulate certain requirements, some of which concern the construction of underground structures to isolate areas from active workings, such as the provision of refuge alternatives. The primary purpose of a refuge alternative (RA), whether mobile or BIP (built-in-place), is to provide a safe haven for miners who are unable to leave their working location due to hazardous gases or a blocked escape path immediately following an explosion.