bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Plastic Dissipation on the Behaviour of Hydraulic Fracturing in a Saturated Porous Elasto-Plastic Media Based on the Assumed Enhanced Strain (AES) Method
Authors: Zhang Jianfeng , Hong Yi , Liu Fushen , Wang Lizhong 
Published: September 2022

ABSTRACT:
Despite the extensive numerical investigations into hydraulic fracturing with various methods, the constitutive behaviour of the host materials in most of these studies is assumed to be linearly elastic. Under many circumstances, hydraulic fracturing has to take place in geo-materials that exhibit strong plasticity, e.g., geologically stored CO2 fracturing through the overlain clayey caprock. The effect of plastic dissipation accompanying hydro-fracturing on the fracture geometry (e.g., length and aperture) and the near-tip stress field in an elasto-plastic material remains unclear. Meanwhile, there is a lack of numerical tool that enables simulation of discontinuity while taking incremental elasto-plastic constitutive behaviour of the host material into account. In this study, a coupled hydro-elasto-plastic model for investigating and quantifying the effect of plastic dissipation in hydraulic fracturing process is proposed. This is achieved by implementing an incremental hardening/softening elasto-plastic model (i.e., Modified Camclay model, or MCC) into the assumed enhanced strain (AES) method, in conjunction with a coupled flow-deformation approach. The role of plastic dissipation on fracture geometry and the near-tip stress field are interpreted, and discussed with their practical implications.

1. INTRODUCTION
Hydraulic fracture is an important issue encountered in multiple natural processes and engineering applications, such as in the case of CO2 storage, induced cracking under hydraulic structures or stimulation of oil or gas exploitation. Fracturing deformation can significantly influence the permeability and strength of the host materials. Thus, accurately predicting the hydraulic fracturing process is vital to many engineering applications. During the past several decades, numerous research works have been conducted to develop the hydraulic fracture modeling techniques, including the analytical solutions and numerical simulators (Adachi et al., 2007). Notably, most of the existing studies are based on the linear elastic fracture mechanics (LEFM). This may not be suitable for the purpose of predicting fracture characteristics in geo-materials that exhibit strong plasticity, such as the ductile shales and mudstones.
Automated Extraction of Borehole Breakout Properties from Acoustic Televiewer (ATV) Data
Authors: Yang J. , Goodfellow S. D. , Harrison J. P. 
Published: September 2022

ABSTRACT:
Analysis of borehole breakouts is a widely used indirect method to estimate in situ stress and assess borehole instability. The Acoustic Televiewer (ATV) is commonly used to log borehole breakouts, but noise inherent to ATV data affects the interpretation of the breakouts. ATV data are usually interpreted manually with associated low efficiency and high cost, and to overcome these deficiencies here we propose a high performance combined de-noising procedure based on the median filter and deep learning techniques. We investigate the use of a convolutional neural network (CNN) method to automate the process of breakout identification, by extracting the underlying relationship between the ATV data and the borehole breakouts. We show that the CNN method can capture breakouts with reasonable accuracy, and when compared to manual procedures the new technique offers both procedural efficiency and reduced interpretation costs.

1. INTRODUCTION
Breakouts occur in borehole walls when the induced stress exceeds the local rock strength. Their presence is thus indicative of high in situ stress conditions, and it is therefore valuable to interpret and analyze them in order to assess borehole stability.
Two kinds of borehole imaging devices are in wide use: optical imaging tools and acoustic imaging tools. The Acoustic Televiewer (ATV), a popular acoustic imaging tool, is the source of the data used in this work. The ATV transmits ultrasonic waves out to the borehole wall, and records the travel time and the amplitude of the echo. The locations and sizes of breakouts can be obtained from interpretation of ATV data.
Currently the process of breakout interpretation is conducted manually, with associated low procedural efficiency and high costs. As a means of avoiding these shortcomings, we set out to investigate whether modern deep learning methods can provide efficient tools for automatic detection and interpretation of breakouts in ATV data. Deep learning segmentation methods are widely used in many different fields, such as identifying tumor boundaries in MRI images (Ranjbarzadeh et al., 2021), delineating infected regions or lesions of lung lobes due to COVID-19 infection in X-ray and CT images (Shi et al., 2021), and detection of cars, traffic signals and pedestrians for self-driving motor vehicles (Song et al., 2018).
Comparative Analysis of Synthetic and Steel Mesh Performance
Authors: Benton D. J. , Sweet D. J. , Emery T. M. 
Published: September 2022

ABSTRACT:
The Spokane Mining Research Division (SMRD), of the U.S. National Institute for Occupational Safety and Health (NIOSH) is continuing research on the mechanical behavior of primary surface support components in mining ground support systems. Mining ground control safety often depends on supporting, or at least containing, the ground between rockbolts using what is referred to as local, surface, or areal ground support. Steel mesh, in various combinations and with other components, is often used to accomplish this, as well as to retain loose rock. Local ground support is an integral part of maintaining a safe underground operation. However, as underground hard rock mining continues moving towards automation, increased challenges regarding support installation and maintenance will create a need for a new generation of mesh support systems. Advanced materials engineering has created various synthetic meshes to meet this need. This study begins a process of compiling technical information on multiple types of mesh performance, leading to an eventual comprehensive index for industry use. Using SMRD’s high-energy high-deformation (HEHD) testing machine, a program was developed to assess the behavior of a variety of steel and synthetic mesh products in quasistatic loading conditions. The data from these tests were used for comparative analyses of the force-displacement and energy-displacement characteristics of conventional steel meshes to synthetic meshes. Considerations were also given to several additional operational and performance factors, including corrosivity, flammability, durability, and handling. This work was completed as part of the SMRD mission of improving the health and safety of underground metal mine workers, and this paper presents the findings of these tests.

1. INTRODUCTION
Mining in ground that may fail from the combination of in situ and mining induced stress is commonplace. Ground support elements are installed to reinforce such ground and preserve personnel and mine safety. Typically, the strength of support is considered key, and is used to prevent or halt ground failure. In stiff rock masses, confining stresses generated by the ground support system are very small compared with the stresses associated with rock fracture, and the support pressure will have no direct effect on fracture initiation (Ortlepp, 1969). However, ground movements driven by creep of weak ground or seismic loading may be somewhat effectively managed by support that is able to yield with the ground in a safe manner while maintaining confining pressure on the rock in the immediate perimeter of the opening. In addition, it is usually desirable to contain ground between rockbolts to protect miners from loose rock that might fall or be ejected (Potvin and Hadjigeorgiou, 2020).
Laboratory Investigation Fracture Penetration in Multi-Interlayers with the Cyclic Hydraulic Fracturing
Authors: Tang M. R. , Zhang G. Q. , Lyu Y. J. 
Published: September 2022

ABSTRACT:
In the tight reservoirs of Ordos Basin, shale interlayers are abundant. The mechanical properties of interlayers are different greatly from the adjacent sandstones, affecting the vertical propagation of hydraulic fractures, and resulting in a poor reservoir simulation with conventional hydraulic fracturing. The cyclic fracturing is an effective method to improve the efficiency of stimulation in such reservoirs. To verify the penetrating feasibility of hydraulic fractures with the cyclic fracturing and the conventional hydraulic fracturing, stimulation tests with true triaxial stresses are used to simulate the cyclic hydraulic fracturing in outcrop blocks of 300 × 300 × 600 mm. Hydraulic fractures form in the shale interlayer and penetrates both neighboring layers of sandstones. From visual observations and 3D scanning of the fractures, hydraulic fracture penetrations shows that: (1) Hydraulic fractures in the shale interlayer are complex, and a series of horizontal fractures along the bedding exist, which makes it difficult for fractures penetrate into the adjacent sandstones with conventional hydraulic fracturing; (2) Different from conventional hydraulic fracturing, hydraulic fractures can penetrate the neighboring sandstones from shale interlayer with the cyclic fracturing.

1. INTRODUCTION
In recent years, the production of unconventional oil and gas has increased rapidly (EIA, 2021). The Ordos Basin has tremendous reserves of unconventional oil and gas resources. Shale oil in the Ordos basin are over 10 billion tons (Zhou et al., 2020). The production of shale oil in Chang 7 is of great significance for alleviating China’s overly dependence on importing oil and gas and guaranteeing national energy security (Fu et al., 2019).
The shale oil in Chang 7 formation can be divided into three types (Yang et al., 2016) according to lithology, the thickness of sand body and other factors. Type I shale oil has been developed a lot (Fu et al., 2020), and the Qingcheng Shale oil field with an annual output of one million tons of crude oil has been built. However, for Types II and III shale oil, with many interlayers, the thickness of sand body is generally less than 5 m. The reservoir changes rapidly laterally and is strongly heterogeneous. In horizontal well drilling, it is easy to drill into interlayers, resulting in frequent encountering interlayers (Jiao, 2020). As a result, many sections are abandoned with conventional hydraulic fracturing.
Time-Series Event Prediction for the Uranium Production Wells Using Machine Learning Algorithms
Authors: Merembayev Timur , Amanbek Yerlan 
Published: September 2022

ABSTRACT:
The efficient estimation of the production rate in the uranium reservoir plays a vital role in the evaluation of operational performance. This paper presents the data-driven production model in the uranium field using LightGBM for the data from the Kazakhstan deposits. We focus on predicting the fault events of the well production solution. Numerical results of this investigation show that LightGBM achieves an accurate prediction with wavelet transformation. The evaluation of the model score is conducted by using metrics such as Recall and F1. With feature engineering by wavelet transformation, we obtained the recall of 0.84 and f1 of 0.89. The LightGBM model with the Morlet wavelet transformation can be useful to solve the issue of prediction maintenance of production well.

1 INTRODUCTION
Uranium production has been gaining importance in recent years since it can be utilized for sustainable nuclear energy, which is also a low-carbon energy source. Due to the Covid-19 pandemic in the world, the optimization of uranium production is required to meet limited demands. In situ leaching (ISL) or in situ recovery (ISR) technology is widely used for uranium production in many countries, including the US, Canada, Russia, China, Kazakhstan. Kazakhstan has a large portion of the world’s uranium production. The main deposits utilized the ISL technology for the production places such as Inkai, Mynkuduk, Moinkum, Kanzhugan, and others (Grancea et al., 2020). ISL method is one of the key recovery technology for uranium in the Kazakhstan fields. In this method, the sulphuric acid is injected into the subsurface to extract pregnant uranium solutions to the surface (Grancea et al., 2020). Next stages, the pregnant solutions go through several chemical processes and refinement steps to recover a uranium concentration.
The literature on the modeling of well production shows a variety of approaches, particularly the flow and transport simulations in the oil and gas industry. In (Regnault et al., 2015), the reactive transport model in 3D was proposed to predict the production of uranium solution. In this model, the accuracy of the result can be achieved by using detailed information on the geometrical properties. To improve computational time of the reactive transport model, parallelization with GPU was developed for the streamline-based simulation in (Tungatarova et al., 2020). Asymptotic analytical solution of the 1D flow with chemical reaction was developed by (Panfilov et al., 2016). This model was verified qualitatively by the result of laboratory experiments for the uranyl sulfate.
A Numerical Comparison of Linear Elastic and Cohesive Fracture Models for Hydraulic Fracturing Based on Assumed Enhanced Strain (AES) Method
Authors: Liu Fushen , Zhang Jianfeng , Cheng Zhang , Hong Yi 
Published: September 2022

ABSTRACT:
Geomaterials are porous, and there are air, water and other liquids inside the pore space. Pore pressure fluctuation may result in the change of contact forces between the solid grains. The deformation of solid skeleton changes the size of pore and therefore the fluid flows inside the pore space. The coupled process is often described with the mixture theory in continuum mechanics. Localized deformation may lead to the displacement discontinuity or the fracture, increasing the complexity of the whole fluid-solid coupled process. Numerical simulations of the complex processes in the subsurface are essential in understanding many geoengineering systems, such as hydraulic fracturing, geological fault reactivation, waste water management, geothermal energy extraction and CO2 sequestration and so on. This paper presents an assumed enhanced strain (AES) finite element method to model the fracture evolution in porous media, where the discontinuous function enrichments are introduced into the displacement approximation to simulate fracture deformation. The enriched degrees of freedom can be removed by the standard static condensation method, which means the method does not introduce additional global system of equations. The mass and stress coupling is described by the standard Biot’s poro-elasticity theory. The numerical method is verified by the mesh sensitivity studies and comparisons with analytical solutions. Particularly, with the AES framework, we have numerically compared the cohesive fracture model and linear elastic fracture mechanics model for simulating hydraulic fracture propagation in porous media.

1 INTRODUCTION
Predicting the mechanical behavior of subsurface fractures is crucial to many engineering practices, especially in the industry of energy resources. Subsurface processes, such as hydraulic fracturing and induced seismicity, pertains to the fracture deformation and propagation driven by fluid flows in subsurface porous media. Hydraulic fracturing is dominated by the opening mode, while induced seismicity may be dominated by the shear modes. Fracture deformation and propagation can also significantly impact subsurface fluid flows, by providing additional flow conduits or barriers to the subsurface. Therefore, understanding the interaction between fractures and fluid flows in porous media is key for the comprehension of those subsurface processes. The motivation of this work is to provide a convenient finite element framework to simulate fracture propagation coupled with fluid flows in the complex subsurface environment.
Composition and Structure of the EGS Collab Test Bed 1 Based Upon Electrical Resistivity Tomography, Core Compositions, and Wireline Logging
Authors: Roggenthen W. M. , Johnson T. C. , Crandall D. M. , Paronish T. J. , Ulrich C. 
Published: September 2022

ABSTRACT:
The EGS Collab project drilled eight 60 m long boreholes at the Sanford Underground Research Facility (SURF) at a depth of 1.5 km to support rock fracturing and stimulation investigations. The test bed was in a complexly folded metasedimentary carbonate mica phyllite with a NW-SE structural grain. Monitoring included electrical resistivity tomography (ERT) that shows the presence of a well-defined electrical conductivity high that defines a fold structure occupying much of the test bed with an orientation similar to the local structure. The nature of this folded conductive unit was evaluated using a range of methods characterizing the rock and geophysical properties. These included core examination, high resolution XRF analyses on selected core intervals, and wireline geophysical logs. Electrical resistivity profiles from the wireline geophysical surveys are consistent with the electrical resistivity tomographic three-dimensional images, and the XRF profiles show elevated levels of sulfur in the vicinity of the interpreted conductivity anomalies. The compositional and wireline logging data are consistent with interpretations from the ERT data. Based upon these observations the best candidate for the source of the high electrical conductivities is the presence of significant amounts of sulfides within the unit making up the folds.

1. INTRODUCTION
The EGS Collab Project has developed two test beds within the underground of the Sanford Underground Research Facility (SURF) located in Lead, SD, USA. The test beds support investigations of fracturing, stimulation, and modeling of these processes at the 10-meter scale in crystalline rocks (Kneafsey et al., 2018). The experiments support the implementation of geothermal utilization by improving the ability to predict and control fractures created and stimulated during the experiments (Kneafsey et al., 2019; Kneafsey et al., 2020). The first test bed (E-1) is located on the 4850 Level of SURF (1.5 km below the surface), and the second (E-2) is located on the 4100 Level. Of these experimental areas, only results from Test Bed E-1 will be discussed here. A major part of the monitoring of the test bed experiments consisted of the application of a range of geophysical techniques that were active as the fracturing and stimulation of regions in the test bed were conducted. These techniques were also employed to characterize the state of the test bed prior to the experiment initiation.
Comparison of Sand Onset and Sand Mass Models in a Field Case
Authors: Papamichos E. , Furui K. , Berntsen A. N. , Rolli O. A. , Morita M. , Koch C. , Li G. , Morgan S. , Nes O.-M. , Yao Z. 
Published: September 2022

ABSTRACT:
Sand production onset and mass/rate predictions are difficult to validate in the field because the field sand production data are often unreliable. To overcome this difficulty recent research has concentrated in representing as realistically as possible the field conditions in laboratory experiments and focused on the effects of fluid saturation of the test specimens and the effects of stress anisotropy. The laboratory results were used to calibrate a semi-analytical model and a numerical nonlinear finite element model for developed for sand onset and sand mass/rate prediction studies. The correlations pertain to sand production functions that depend on the fluid saturation and stress anisotropy and account for the observed physical behavior in the laboratory. The models are compared for field case analyses including parametric studies of various completion and operational parameters. They show the importance of anisotropy and fluid saturation during the upscaling from laboratory data to the field.

1. INTRODUCTION
Sand management of sand producing field requires accurate predictions of sand onset and sand mass to optimize the well completion method and the drawdown and depletion during the life of the well. Research in sand production has addressed various issues in this topic by e.g., classifying sandstones according to their sand production potential, by looking at multiphase flow conditions and the effect of water breakthrough and gas flow in gas reservoirs.
Recent research has concentrated in representing as realistically as possible the field conditions in laboratory experiments and focused on the effects of fluid saturation of the test specimens and the effects of stress anisotropy. The laboratory results are used to calibrate both a semi analytical model for sand onset and sand mass prediction and a numerical model with empirical correlations based on field data. Both models are used in the industry for field case analyses and sand onset and mass predictions.
Thermal Imaging for Rockfall Detection
Authors: Wellman E. C. , Schafer K. W. , Williams C. P. , Ross B. J. 
Published: September 2022

ABSTRACT:
Under a NIOSH research grant, the Geotechnical Center of Excellence (GCE) evaluated the capability and limitations of thermal cameras to detect rockfall events and the conditions that can lead to rockfall. This two-year study tested four different thermal imaging cameras in controlled rockfall experiments and long-term surveillance tests in various mines and conditions. The cameras can detect rockfall events at less than their resolution as rockfall creates larger craters, impacts, and dust trails visible in the thermal IR. The surveillance test determined that the cameras work in both day and night conditions under a wide range of conditions. However, fog, heavy precipitation (rain, snow, hail), and dust limited visibility in the thermal IR.
Four thermal infrared cameras were acquired for the project. The cameras were installed on a mobile mine monitoring platform. The project tested thermal imaging cameras’ effectiveness to detect and record rockfall events and rockfall hazards in surface mining operations as a method to protect mine workers from the risks of rockfalls. One of the primary findings of the project is that off-the-shelf cameras can be used to increase situational awareness at the mines in low-light conditions. This presentation will document camera selection, resolution, and results from the project.

1. INTRODUCTION
The Thermal Imaging project for Rockfall Detection Mobile Monitoring Platform (MMP) has been deployed at seven different open-pit mines for over one year. Since April 7, 2021, the MMP has been deployed with all four thermal cameras installed and operational at seven Western US and Canada mine sites. The system was initially deployed at two different mine sites in Arizona starting in January 2021 with three cameras.
The research project has tested thermal imaging cameras’ effectiveness in detecting and recording rockfall events and rockfall hazards in surface mining operations as a method to protect mine workers from the risks of rockfalls. One of the primary goals is to identify cost-effective, off-the-shelf systems that can be integrated with existing slope monitoring systems or installed separately as a part of routine mine observations.