bluuebunny/crossref_metadata_2025_split huggingface dataset:
Micro-Seismic Monitoring in Mines Benefits and Limitations
Authors: Rebuli D. B. 
Published: August 2024

ABSTRACT:
Seismic monitoring is a useful tool in understanding the rockmass response to mining. The waveforms recorded by sensors contain information not only about where and when a seismic event occurred but also about the driving stresses, failure mechanism and the intervening rockmass. It is also good to understand the limitations of this tool as they should guide the system design, overall monitoring objectives and the analysis of the seismic data. This paper discusses what information can be extracted from a mine seismic system, how this information can be useful to the mine in understanding their rockmass interaction with mining, but also the limitations associated with this information. Only then can the data be interpreted correctly.

1 INTRODUCTION
Seismic monitoring in a mining environment is a unique tool, in that it is continuous in time and can monitor a 3D volume. It is also a powerful tool, in that it can monitor ground motions over multiple orders of magnitude. For example, in the velocity domain, the sensors can measure ground motions from fractions of μm/s to tens of mm/s. The commonly used magnitude scales, which are logarithmic scales, typically extend from around −2.0 to +2.5 for mining applications, which is at least four orders of magnitude. The sources of the measured ground motions can be many and will be discussed below, but the main objective is to monitor sudden inelastic deformations as a result of stress changes in the rock mass due to mining. This gives a powerful monitoring tool, but it is still just one of many tools available to rock mechanic practitioners.
One of the first questions when contemplating or designing a seismic system should be "What is the objective?". Mendecki et al. (1999) describes seismic monitoring as enabling the quantification of exposure to seismicity. They then list a number of specific objectives, namely location of potential rockbursts, prevention, control, warnings and back-analysis. Identifying the objectives is important, as it will determine such details as which sensors to use, how many and how dense a seismic array is needed and what type of alerts are required.
This paper will not go into too much detail about seismic monitoring systems and array design, except where needed to clarify a concept. However, a short introduction to seismic sources and sensors is useful.
A New Approach to Model Irregular Particles Breakage with Deploying Image Analysis Techniques on Discrete Element Method
Authors: Amir Hosseini M. , Tahmasebi P. 
Published: August 2024

ABSTRACT:
While the conventional Discrete Element Method (DEM) is a popular tool for investigating breakage, it falls short of accurately capturing the natural morphology of particles. Moreover, previously introduced techniques for simulating irregular particles' breakage have simplified the breakage into only two splitting and chipping mechanisms, which tend to depict fractures as linear or planar. To fill the research gap, therefore, we have introduced an innovative 3D breakage model that incorporates the actual shape of grains and all key breakage mechanisms, including splitting, chipping, and fragmentation. To consider all fracture mechanisms in our simulations, we deploy Dijkstra's algorithm within the particle's stress field to obtain the fracture surface(s). Following the identification of these fracture surface(s), we employ intersection set operations and a labeling technique to generate multiple sub-grains. To demonstrate the accuracy of our approach in modeling breakage, we compared our method to compression experimental data on a three-particle system. Our study involves quantitative analyses of volume, displacement, and rotational motions. Our results underscore the significance of particle displacement as a key factor in the breakage process while emphasizing the influence of rotational motion. Moreover, our findings effectively capture distinct stages of breakage and rotational movements.

1. INTRODUCTION
Particle breakage can be seen in various industrial and/or research applications. In breaking systems, particles' pre-breakage and after-breakage behavior can influence the system considerably. To be more specific, the breakage can be seen in geotechnical (H. Y. Li et al., 2020; Z. Wu et al., 2019), ocean engineering (Shen et al., 2023), pharmaceutical (Picart et al., 2022; Xiao et al., 2022), etc. As mentioned, the breakage can happen on different scales. Although particle breakage in some cases is a micro-scale phenomenon, the change in characteristics of each system can lead to macro-scale change. For instance, the change in the shape of a grain in a pack of particles can change the stress distribution in such a system. Moreover, the change in the geometrical properties of a grain can add complexity to the problem due to the new contacts between sub-grains. Hence, understanding the breakage process is vital. Particle breakage has been divided into chipping, splitting, and fragmentation. When particles (i.e., sub-particles) have considerable size differences after breakage, the breakage is named chipping. However, splitting is the way of breakage where sub-particles have the same and/or close size; when a particle turns into several pieces, fragmentation breakage occurs. Comprehensive review on the breakage of granular matters can be found elsewhere (Tahmasebi, 2023).
New Afton Convergence Monitoring and Rehabilitation Planning in the B3 Footprint
Authors: Owre S. , Tilley E. , Kamp C. 
Published: August 2024

ABSTRACT:
New Afton's B3 block cave footprint has been in steady state production since 2022. During mining, the production footprint is subject to changing stresses that have been observed to cause squeezing and convergence of the drift profile at drawpoints and extraction drives. This can present challenges to the mining operations in terms of drift stability and accessibility of the footprint for equipment. Robust geotechnical monitoring practices have been developed to address this. Convergence is monitored using periodic visual inspections, LiDAR scanning, and multi-point borehole extensometers. These geotechnical monitoring activities generate data that requires interpretation and review during rehabilitation planning. Geotechnical monitoring data is assessed before, during, and after rehabilitation to understand the effectiveness of rehabilitation activities. This paper discusses two practical examples of New Afton's convergence monitoring and rehabilitation practices in the B3 footprint with the objective of documenting the importance of timely and well-planned rehabilitation in achieving safe and efficient production.

1. INTRODUCTION TO NEW AFTON
The New Afton Mine is a block caving operation, located approximately 10 kilometers outside of Kamloops and 350 kilometers northeast of Vancouver in British Columbia. The copper-gold orebody is situated on the Stk'emlupsemc te Secwépemc territory, within the unceded traditional lands of the Secwépemc nation.
In 2021 and 2022, New Afton completed its first two Block Caves on Lift 1, the West and East Caves, which mined over 24.5 MT and 23.7 MT respectively. Currently, New Afton successfully initiated and is monitoring steady state caving of a third cave (B3) beginning in January 2022 with 8.8 MT (probable tonnes). Production involves milling over 8,000 tonnes per operating day from the B3 cave. Footprint development and drawbell blasting is ongoing at a fourth cave (C-Zone), which comprises 29.5 MT (probable tonnes). These mining areas are shown in Figure 1.
Numerical Simulation of Shallow Conductor-Soil Displacement Characteristics in Deep Water Drilling
Authors: Zhang Minghe , Yang Jin , Wang Haige , Cui Longlian , Liu Qi , Kong Lulin , Sun Ke , Jia Wanting 
Published: August 2024

ABSTRACT:
Since the shallow soil is mostly composed of clay with weak cementation, the subsea wellhead is easy to be affected by external loads in the initial stage of installation, and the stability of the subsea wellhead is weak, which is prone to serious accidents such as sinking and tilting of the wellhead, resulting in significant economic losses and threatening the safety of deep-water operations. The traditional p-y curve calculation model cannot well reflect the vibration of the subsea wellhead and the detachment and displacement of shallow soil around the surface conductor. However, the Goodman contact element model in numerical simulation can simulate the discontinuity characteristics of the conductor-soil contact interface. In this paper, the numerical simulation method is used to discuss the vertical displacement characteristics of subsea wellhead under cyclic dynamic load and the displacement characteristics of shallow soil particles in different directions and depths around the surface conductor, and the factors affecting the displacement characteristics of conductor and soil are analyzed by load type, conductor installation depth, conductor diameter, and wellhead height above the mudline. It is important to explore the displacement characteristics of subsea wellheads and shallow soil for the design and stability evaluation of subsea wellheads.

1. INTRODUCTION
The construction of a subsea wellhead is the key to the success of deep-water oil and gas drilling, in which the structure of a subsea wellhead mainly depends on the interaction between the surface conductor near the mudline and the surrounding soil to provide bearing capacity (Zhang et al., 2021).
After the installation of the subsea wellhead, it is dynamically stable under the external load of the marine environment and the upper pipe string, which is reflected in the horizontal and reciprocating movement of the surface conductor near the mudline (Zhang et al. 2023). The surface conductor under the mudline has a repetitive action of detachment and extrusion with the surrounding soil, and the position and mechanical property parameters of the soil have changed significantly. As a result, the soil near the mudline cannot provide enough vertical friction for the surface conductor, and part of the soil separated from the surface conductor surface will enter the gap between the surface conductor and the soil, accumulate at the bottom of the gap and become compacted with the reciprocating movement of the conductor, affecting the stability of the subsea wellhead (Su et al. 2010).
Experimental Study on Wall Stability of Acid-Etched Fractures Carbonate Reservoir
Authors: Zhang X. D. , Zhou Jun , Zhou Zhou 
Published: August 2024

ABSTRACT:
It is difficult to maintain the conductivity of acid etched fractures in deep carbonate reservoirs. The instability mechanism of acid etched fractures is analyzed by mineral composition analysis, laser scanning before and after acid etched, and continuous strength measurement. By determining the morphology and mechanical characteristics of the fracture wall, the construction parameters such as acid etched time and displacement can be obtained. The continuous strength of the same parts of the rock samples before and after acid etched was compared, and it was found that the strength of some areas increased after acid etched. The main reason for the increase in strength is that the calcite is dissolved by the acid solution, while the dolomite covering the bottom is exposed, and the dolomite strength is higher than the calcite strength. The compressive strength of the dolomite-containing part of the same rock is about 40∼50MPa higher than that of the calcite part.

1. INTRODUCTION
As a reservoir with abundant oil and gas reserves, carbonate rock has become an important research object of oil and gas exploitation. Carbonate reservoir contains 48% of the world's oil and gas reserves. With the discovery of many deep and ultra-deep carbonate oil and gas fields in Tarim, Ordos Basin and other places, the exploitation of carbonate reservoir has become an important research aspect for increasing oil and gas storage and production in China, and acidizing and fracturing is the main technical means for increasing production of carbonate oil and gas fields.
Acidizing fracturing technology is to press acid into the reservoir and form fracture s under conditions higher than the fracturing pressure of the reservoir. At the same time, acid of different systems can react with calcite, dolomite and other rocks on the wall, and non-uniformly etch the fracture wall to form support bodies of different heights. After the completion of construction, the support bodies can effectively support the fractures and make them not completely closed. Finally, a certain length of fracture with flow diversion ability is formed, so as to achieve a production increase effect.
Injection from Well Experiments in Axisymmetric Triaxial Cells: Example of Hydraulic Fracturing
Authors: Kovalyshen Y. , Dautriat J. , Kiewiet L. , Sarout J. , Maney B. , Kager S. , Penny I. 
Published: August 2024

ABSTRACT:
Laboratory experiments involving the injection of fluids through rocks under well-controlled conditions can help better constrain the processes taking place at depth during CO2 geo-sequestration in porous reservoirs, or hydraulic fracturing of tight gas/geothermal reservoirs. This article reports the testing of a new method for injecting a fluid through a cased borehole drilled in a cylindrical rock sample subjected to in-situ stress conditions in a conventional axisymmetric triaxial stress vessel. We use rock samples 1.5 inch in diameter in which a 2-mm wellbore can be drilled along or orthogonal to the sample's axis, which is also the direction of maximum principal compressive stress. The casing is made of 1/16 inch perforated stainless steel tube, cemented with a high-strength epoxy. We report here the results of 3 experiments with samples of American Black granite. Water is injected downhole (at the centre of the sample) through a wellbore drilled along or orthogonal to the sample's axis. In this tight rock, the injection pressure reaches a peak and leads to hydraulic fracturing of the sample in both configurations. In addition to the injection parameters (injection pressure/volume, flow rate), the impact of the injection operation is monitored thanks to 16 to 20 ultrasonic transducers attached to the lateral surface of the cylindrical sample, and operated in both active and passive modes. In the case of a sample with horizontal well we observed high stresses around the well that can be attributed to the relatively small size of the sample. As a result, one should not use this configuration to model fluid injection into rock formations in the field. On the other hand in the tests with a vertical well we observed a low breakdown pressure compared to predictions assuming a homogeneous and infinite elastic medium. We attributed this to the relatively large grain/flaw size compared to the well diameter, and the probable stress heterogeneities associated with the epoxy-sealed sections of the well. Finally, we observed a dependency of the P-wave velocity on the state of confining stresses applied to the sample. We argue that this dependency can be, at least partly, explained by the progressive deformation of the rock/sensor interface, rather than solely by the intrinsic stress dependency of the tested rock (e.g., micro-cracks closure with increasing mean compressive stress). We can also report that combined active and passive ultrasonic monitoring allows for an adequate reconstruction of the spatio-temporal evolution of the micro-seismicity induced by hydraulic fracturing.
Influence of Increasing Mean Stress on Rock Fatigue Fracture Characteristics and Failure Mechanism
Authors: Hou Yanan , Wang Li , Liu Yishan , Wu Guangai , Yin Zhiming , Wang Junyan , Fan Baitao , Peng Yan 
Published: August 2024

ABSTRACT:
Pulsating hydraulic fracturing (PHF) is a highly potential fracturing technology. Because it can induce fatigue fracture of rocks and generate complex fracture networks by pumping fracturing fluid in pulse form. Understanding fatigue fracture characteristics and failure mechanism of rocks in PHF is crucial for optimizing fracturing construction parameters. In this paper, a series of fatigue fracture toughness experiments including monotonic loading, constant amplitude with constant mean stress(CACMS) cyclic loading and constant amplitude with increasing mean stress(CAIMS) cyclic loading are conducted, respectively. Moreover, fatigue fracture characteristics under these three cyclic loading forms are compared and analyzed. Furthermore, three-dimensional laser scanning is performed on the samples after fatigue fracture to investigate fatigue failure mechanism. Results show that the fracture toughness under CAIMS cyclic loading and CACMS cyclic loading are lower than that under monotonic loading. The samples subjected to cyclic loading failure dissipate more energy during failure, and the roughness of the rock failure surface is also greater than monotonic loading. The results of this paper help to understand the reasons for the higher efficiency of PHF, and provide guidance for the application of PHF technology.

1. INTRODUCTION
Pulse hydraulic fracturing technology has been proven to be a promising technology (Wang et al., 2015; Ni et al., 2018; Lin et al., 2012). This technique induces fatigue damage to reservoir rock by regulating the pumping of fracturing fluid through pulse pressure or pulse flow rate (Ni et al., 2019). As a result, complex fracture network can be generated through the fatigue failure of reservoir rock (Zang et al., 2013; Xie et al., 2020). According to Hou et al. (2021), reservoir rock is subjected to cyclic load with a constant amplitude and an increasing mean stress (CAIMS) when fracturing fluid is pumped in the form of pulse flow rate. Understanding and optimizing the PHF mechanism requires knowledge of the fatigue failure characteristics of rock under this form of cyclic loading.
A 3D Subspring Network Breakable Voronoi Model for Rock: Laboratory-Scale Behavior
Authors: Potyondy D. O. , Fu W. 
Published: August 2024

ABSTRACT:
A micromechanical model based on the distinct element method that employs the Subspring Network contact model with rigid, Breakable, Voronoi-shaped grains (SNBV model) is described. The SNBV model is an excellent model for rock microstructure that reproduces the damage mechanisms (heterogeneity-induced local tension, closure of an initial microcrack fabric, and grain breakage) that occur at the grain scale. The laboratory-scale behavior of the synthetic material is summarized as follows. The material exhibits behavior during direct-tension and triaxial compression tests that matches the behavior of intact compact rock. The material can be calibrated to match all of the standard material properties and characteristic stresses as well as the microstructural behavior (including grain breakage) of intact pink Lac du Bonnet granite. The material properties consist of Young's modulus and Poisson's ratio corresponding with uniaxial compression and Young's modulus corresponding with direct tension, as well as tensile strength, crack-closure stress, crack-initiation stress, secondary crack-initiation stress to mark the onset of grain breakage, crack-damage stress, and compressive strengths up to 4 MPa confinement.

1. INTRODUCTION
Bonded-particle models (BPMs) provide a synthetic material consisting of a packed assembly of rigid grains joined by deformable and breakable cement at grain-grain contacts, and whose mechanical behavior is simulated by the distinct-element method. BPMs are being used for rock mechanics research and application (Potyondy, 2015). A new type of BPM called the Hybrid Lattice/Discrete Element Model (hybrid LDEM — a version of the DEM that employs Rigid Body Spring Network interactions) with grain breakage was proposed by Rasmussen (2022), who obtained excellent laboratory-scale behavior for pseudo-3D models consisting of a 3D Voronoi tessellation in which each Voronoi cell is one element thick. The subspring network contact model in PFC3D (Itasca, 2024) is like the hybrid LDEM model. This contact model is combined with a new grain-breakage scheme to provide the Subspring Network contact model with rigid, Breakable, Voronoi-shaped grains (SNBV model). The SNBV model provides excellent laboratory-scale behavior in fully 3D models of cylindrical specimens. The work described in this paper is part of a larger effort to evaluate the ability of the PFC3D code to model spalling by constructing a calibrated SNBV material and studying its laboratory-scale behavior during direct-tension and triaxial compression tests, and its tunnel-scale behavior during excavation of the Mine-by Experiment test tunnel (Read and Martin, 1991). This paper focuses on the laboratory-scale behavior of the SNBV material — refer to Potyondy et al. (2024) for a comprehensive discussion that includes the tunnel-scale behavior as well as a mechanistic explanation of the spalling process.
Modeling of Thermal-Mechanical Impact on Wellbore Integrity Due to CO2 Injection
Authors: Sun Zhuang , Fager Andrew , Crouse Bernd 
Published: August 2024

ABSTRACT:
Wellbore integrity is critical to the long-term security of CO2 geological storage. During CO2 injection, the significant temperature difference between the injected CO2 and formation at depth will stress the near wellbore region, potentially leading to generation of leakage pathways. In this work, we perform a numerical study to investigate the role of CO2 injection temperature and pressure based on a 3D coupled thermal-hydro-mechanical model of the formation-cement-casing system. The study takes advantage of the publically available dataset of the Northern Lights project. We present a multistage finite element model that considers the sequential changes of stress and displacement during each stage of the CO2 injector life, such as drilling, casing, cementing, completion, and injection. We simulate a cyclic thermal loading and the results show that no debonding occurs at cement-casing or cement-formation interface during cooling and heating phases, which indicates that the high in-situ effective horizontal stresses tend to mitigate the negative impacts of thermal stresses on wellbore integrity. We also study the impact of several key factors such as the cement elastic moduli and thermal properties. The numerical model offers a solution to quantify the potential thermal-mechanical impact across the entire lifecycle of CO2 injector.

1. INTRODUCTION
Carbon capture, utilization and storage (CCUS) is a critical technology to remove the massive amount of CO2 from the atmosphere and mitigate global warming (Bachu, 2008; Benson & Cole, 2008; Pacala & Socolow, 2004). It will be virtually impossible to achieve net zero goals without CCUS (IEA, 2020). The storage aspect of CCUS involves the injection of CO2 into subsurface saline aquifers or depleted oil and gas reservoirs through wellbores. However, one challenge of CO2 storage is that injected CO2 may find leakage pathways out of the storage reservoir, which adversely affects the surrounding ecosystem and may ultimately re-emerge into the atmosphere (Bachu & Bennion, 2009; Rutqvist et al., 2012; Sun et al., 2023, 2022). It is crucial to prevent leakage from wellbores to establish long-term CO2 storage (Bachu & Watson, 2009; Wigand et al., 2009).