bluuebunny/crossref_metadata_2025_split huggingface dataset:
Appraisal of Boreability Characteristics of Rocks to Estimate the TBM Advancement
Authors: Yagiz S. , Yazitova A. , Smirnov G. , Thyagarajan Vinayak M. , Hassanpour J. 
Published: August 2024

ABSTRACT:
The production rate of mechanical excavators such as tunnel boring machine (TBM) and roadheader depend on the geotechnical properties of rock, machine specifications and operational parameters. TBMs are being utilized for the construction of various tunnels for the purpose of access, conveyance of ore and waste, drainage, exploration, water supply and diversion in mining and civil projects. To obtain the maximum production with optimum power from any mining or civil operation, the excavator should be chosen carefully depending on the ground condition and mass rock characterization. Examining those rock characteristics, evaluating the geological structures in the field, and choosing the right TBM for excavation are the main geotechnical and technological investigation steps to conduct the project. In this paper, intact rock properties e.g., strength, density, brittleness and mineralogical features of rock, rock mass characteristics such as frequency and orientation of discontinuities are examined and their influence of TBM advancement are highlighted.

1. INTRODUCTION
Currently, mechanized excavation is one of the most popular and fastest way of rock and soil excavation around the world due to its high mechanization level, great operational efficiency and low environmental impact. However, the application of the method requires an accurate estimation of possible costs in the primary and secondary stages of projects. Due to that, the assessment of TBM performance via an either rate of penetration (ROP) or field penetration index (FPI) and rate of advance (AR) as well as utilization (U %) is one of the most effective factors, both in estimating the cost and the operation time of any project. Accordingly, the incorrect estimation of these parameters can lead to irrecoverable economic and time losses in proposed project. The ROP is one of the most commonly used parameters of TBM boring process; however, utilization and advance rate are also connected with ROP due to that these three indicators are the main targets to obtain for project scheduling. In present, different models and relations have been introduced to predict the penetration rate as a function of intact and mass rock and also machine specifications. Numerous simple and comprehensive methods have been proposed for predicting the TBM performance by researchers (Graham, 1976; Farmer and Glossop, 1980; Hughes, 1986; Rostami and Ozdemir, 1993; Palmstrom, 1995; Bruland, 1999; Barton, 2000; Yagiz, 2002; Bieniawski et al., 2008; Gong and Zhao, 2009; Hassanpour et al., 2009; Delisio and Zhao, 2014; Yagiz, 2017; Goodarzi et al 2021; Yagiz et al., 2024), and machine manufacturing companies (such as, Robins and Herrenknecht) throughout the world. These methods are generally based on field, machine and laboratory dataset obtain from laboratory tests. In general, these parameters can be classified into three main categories:
Characterization of Carbonate Rock Fragmentation Under Torsional Impact Loading
Authors: Xu Zhaohui , Ji Ran , Fan Jinzhao , Shi Huaizhong , Fang Chao , Liu Dong , Wang Yongqi , Song Shaobo 
Published: August 2024

ABSTRACT:
In order to study the influence of torsional impact technology on rock stress response, cutting force and other parameters of carbonate rock under different impact amplitude and impact frequency, the crushing test of carbonate rock was carried out by using the method of torsional impact assisted PDC bit, and the single-tooth rock crushing model under torsional impact was established, and the influence of different impact parameters on crushing efficiency was analyzed. The results show that under the condition of reasonable selection of torsional impact frequency and amplitude, torsional impact technology can effectively reduce the rock breaking torque and improve the rock breaking efficiency. The peak Mises stress increases by 42.3%,and the average cutting force of 1.5 times the amplitude is reduced by 10.6%. The research results are expected to provide a scientific basis for accelerating the drilling rate of carbonate rocks.

INTRODUCTION
Geothermal energy, as one of the renewable energy sources, is a resource that can provide low-carbon, renewable loads for the production of electricity and heat, and has great potential for development. Although geothermal energy resources have their unique advantages, taking carbonate reservoirs as an example, the deep geothermal resource reservoirs are characterized by low permeability, high abrasiveness and high hardness, which makes the development of geothermal resources relatively difficult. Geothermal drilling, as the most basic and important part of geothermal development, has been attracting much attention. Expensive drilling equipment, experienced drilling experts and strong financial support are necessary for geothermal energy development. Therefore, reducing the number of drilling days and improving the drilling efficiency are the main ways to achieve the goal of commercializing geothermal energy. Currently, the conventional rotary drilling method is commonly used for drilling wells in carbonate formations, but the low rock crushing efficiency and severe wear and tear of the drill bit of this drilling method, which in turn leads to long drilling cycles and high drilling costs, have severely restricted the large-scale development of geothermal energy in carbonate formations.
Research on the Characteristics of Supercritical CO2 Shock Fracturing Flow Field Based on Numerical Simulation
Authors: Zeng Changhui , Mu Zongjie , Wang Haizhu , Xu Chuanyou , Yi Yonggang , Stanchits Sergey , Cheremisin Alexey , Popov Yury 
Published: August 2024

ABSTRACT:
Unconventional oil and gas have significant resource potential and economic value. Based on the technical method of extracting unconventional oil and gas through supercritical carbon dioxide (SC-CO2) shock fracturing proposed by the research team, a SC-CO2 shock fracturing tool has been developed. Based on computational fluid dynamics and the finite element method, a three-dimensional model was established to simulate the flow field of SC-CO2 shock fracturing. Numerical simulations were conducted to obtain the spatiotemporal distribution patterns of pressure, temperature, and velocity. The results show that under impact load, the maximum stress strain and maximum temperature of the tool occur at the nozzle wall, with a maximum equivalent stress of 409.25 MPa and a maximum total deformation of 0.075 mm, meeting the strength requirements. The SC-CO2 fluid is released through the nozzle, resulting in drastic changes in the flow field temperature, pressure, and velocity, causing a backflow phenomenon and continuously impacting the reservoir. The research results can provide a reference for the development of SC-CO2 shock fracturing tools.

1. INTRODUCTION
Currently, with the advancement of global oil and gas resource exploration and development, unconventional oil and gas have shown significant resource potential and economic value (Wang et al., 2016). However, unconventional reservoirs have issues such as high seepage resistance and poor connectivity (Middleton et al., 2017), leading to high development costs. Therefore, it is necessary to enhance the reservoir, and hydraulic fracturing is the most widely used reservoir modification technology (Li et al., 2024). However, in the development of unconventional oil and gas, water-based fracturing fluid systems face technical challenges such as hydraulic fractures being controlled by formation stress; high water demand and low utilization efficiency (Shahbazi et al., 2020); clay swelling due to water sensitivity, blocking reservoir flow channels, and damaging the reservoir (Ahamed et al., 2019); incomplete flowback contaminating groundwater, and high wastewater treatment costs (Li et al., 2015), which restrict the development and utilization of unconventional oil and gas resources (Wu et al., 2022).
Investigation on the Setting Time Improvement of Geopolymer Cementitious Material Developed for Pumpable Roof Supports
Authors: Motameni S. , Nikvar-Hassani A. , Zhang L. 
Published: August 2024

ABSTRACT:
A novel geopolymer cementitious material (GCM) has recently been developed at the University of Arizona for the construction of pumpable roof supports (PRSs) in underground coal mines. The newly developed GCM not only demonstrated superior mechanical properties but also addressed the cracking issues of the traditional CM when exposed to air. However, during the full-scale production and performance evaluation of the GCM, it was observed that the GCM encountered a self-supporting issue. Specifically, the setting time of the GCM was longer than anticipated, leading to slight buckling during the production of the PRSs. The present study explores different additives to adjust the setting time of the GCM, aiming to improve its self-supporting capacity at the very beginning. To achieve the goal, systematic laboratory experiments were conducted to investigate the setting time and self-supporting capacity of the GCM containing different types and dosages of additives. The rheology, compressive strength, tensile strength, and toughness of the GCM at different conditions were evaluated. X-ray diffraction (XRD) analyses were also performed to study the effect of the additives on the phase composition of the GCM. The results show that with the addition of free lime up to a certain amount, the GCM achieves good self-supporting while maintaining its superior mechanical properties and durability.

1. INTRODUCTION
Pumpable roof supports (PRSs) are used in long-wall tailgates and bleeder entries as secondary roof support in underground coal mines (Fig. 1). The main component of a PRS is the cementitious material (CM). The requirements for a CM to be used in the construction of PRSs include high peak UCS and large residual strength (Barczak & Tadolini, 2008). The currently used CMs in practice are either costly or decompose after exposure to air. Finding an alternative CM is therefore essential to meet the PRS requirements (Nikvar-Hassani & Zhang, 2020).
Recently, a new CM, called geopolymer cementitious material (GCM), has been developed in the Sustainable Materials and Recycling Technologies (SMART) Laboratory at the University of Arizona to improve the performance of PRSs. The newly developed CM not only showed enhanced higher mechanical properties like peak and residual UCS, but also addressed the durability issues of the currently used CM (Nikvar-Hassani & Zhang, 2022).
Study on the Fracture Propagation Mechanism in Deep CBM Reservoirs
Authors: Wei S. M. , ShenTu J. J. , Jin Y. , Chen S. Y. , Gao B. C. , Peng F. 
Published: August 2024

ABSTRACT:
The matrix permeability of deep coalbed methane (CBM) reservoirs is extremely low, but they are abundant in bedding and cleats structures. Hydraulic fracturing is the most effective method for exploiting deep CBM reservoirs. Due to the characteristics of deep coal seam burial and high construction pressure, there is no mature experience to draw from. The bedding and cleats in coal seams are crucial to the initiation and propagation of fractures in deep CBM reservoirs. The existing stimulation conditions of large displacement and large liquid volume make the high fluid loss characteristics of coal rocks more obvious, highlighting the difference in fracture propagation mechanism between deep CBM reservoirs and conventional reservoirs. Addressing the technical challenge of lacking theoretical guidance on fracture propagation mechanism in the current deep CBM reservoirs stimulation, this paper established a dynamic fracture propagation simulation method based on the discrete element method. The fracture propagation mechanism of deep CBM reservoirs was studied by numerical simulation. Through the analysis of the influence of displacement and viscosity, it is found that the initiation of deep CBM reservoirs involves both shear and tensile failure. Under conditions of low displacement and high viscosity, primary fractures are more likely to form along the direction of the maximum horizontal principal stress, while complex fracture networks are easy to form under high displacement and low viscosity conditions. This paper reveals the dynamic mechanism of hydraulic fracture propagation in deep CBM reservoirs, which helps to understand the construction limits of hydraulic fractures in communicating cleats and bedding, and thereby improves the design method of hydraulic fracturing engineering parameter.

1. INTRODUCTION
China has vast reserves of deep CBM resources. If economically viable exploitation and utilization can be achieved, it will greatly promote and propel the development of China's CBM industry into a new phase. As indicated by Figure 1, the production of CBM in China has experienced nearly linear growth from 2009 to 2018 (Li et al., 2020).
Compared with shallow coal seams, deep coal seams have unique reservoir geological characteristics such as high geostress, high temperature, high pressure, low porosity and low permeability. Large-scale volumetric fracturing of horizontal wells is currently an effective measure for industrialized exploitation of deep CBM reservoirs. The shape and scale of the artificial fracture networks will directly determine the production of CBM.
Investigation into the Rock Mass Response to Pillar Extraction in a Hard Rock Tabular Mine
Authors: Moyo S. , Chikande T. , Zvarivadza T. , Masethe R. T. , Adoko A. C. , Onifade M. , Firoozi A. A. 
Published: August 2024

ABSTRACT:
Historically, secondary pillar extraction has been successful in the soft rock mining environment. Several hard rock platinum mines have conducted selective remnant extraction with backfill as a regional support measure. A hard rock tabular platinum mine instigated the extraction within a non-yield pillar layout without backfill support. The mine is situated within the Great Dyke of Zimbabwe in a shallow depth environment of approximately 100m. Pillar extraction without backfill in a hard rock mine is a novel mining method. A study was carried out to make a quantitative comparison between the various design parameters and the rock mass response measurements. The primary mining utilised the mechanised room and pillar mining method to extract ore from the wide tabular reef. Similar, low profile mechanised equipment with additional automated systems were adopted for ore extraction and transportation to the surface crusher. The risks associated with the extraction of pillars include large localised falls of ground due to wide spans, pillar run, high severity injuries due to windblasts and large regional collapses through to the surface. The pre-feasibility study for the mine layout design used MAP3D to assess the expected displacement and stress limits post-extraction. MAP3D uses the boundary element method of analysis and has an in-built CAD system for stress analysis and 3-dimensional visualisation of models. A monitoring strategy consisting of displacement, deformation, stress change, ground motion and groundwater level measurements was put in place to record the variations resulting from the pillar extraction. The rock mass response analysis aimed at trending the monitoring results, conducting a comparison to the design parameters and previous pillar collapse trends. Minor stress, strain, and displacement changes have been recorded within a period of one year since the project began with no visible deformation noted on accessible pillars. The current system was identified as including the hazard identification and first-pass monitoring stages. Real-time monitoring systems with a higher sensitivity are required to ensure long-term data retrieval and timeous emergency response.
Rockfall Occurrence and Precipitation Modeling to Simulate Correlation Patterns
Authors: Williams Frances , Walton Gabriel 
Published: August 2024

ABSTRACT:
Rockfalls are naturally occurring geohazards that are frequently associated with steep or vertical slopes. Falling rocks have the potential to disrupt transportation systems, including highway and railway passages. A common trigger known to influence the frequency and severity of rockfall events is precipitation. For many rock slopes, rainfall is considered the primary rockfall trigger. In some cases, the relationship between rainfall amount and rockfall frequency presents as a linear correlation when studied using data averaged over an extended period (i.e. due to monitoring data resolution limitations). However, when considered over smaller timescales, the actual underlying relationship is likely to be non-linear, and may involve step changes in behavior at different levels of rainfall (i.e. threshold-based behavior). The aim of this study is to evaluate the ways in which the apparent relationship between precipitation and rockfall depends on the time period over which data are being compared. We achieve this by developing a simulation that includes several components that overall model rockfall outcomes on a day-to-day basis. Daily precipitation totals are simulated according to a lognormal distribution. Lognormal distributions were also used to represent different ranges of rockfall volumes corresponding to different precipitation thresholds. The model can simulate daily rockfall volume distributions using varying probabilities of occurrence to reproduce the differences in characteristics of various hypothetical rock slopes. Overall, the simulation results are used to interpret how the appearance of correlations between variables averaged over longer time scales depends on the nature of the underlying precipitation-rockfall relationships on a day-to-day basis.

1. INTRODUCTION
Rockfalls represent a significant geohazard, particularly for vertical slopes along transportation corridors. Among the various factors influencing rockfall occurrences, liquid precipitation (rainfall) is a primary trigger (Birien and Gauthier, 2023, Pratt et al., 2018). Studies with a larger monitoring interval often reveal an apparent linear correlation between rainfall and rockfall frequency due to data resolution constraints (Banji et al., 2021; Malsam, 2022; Weidner & Walton, 2021); however, examination on a smaller time scale suggests a non-linear relationship characterized by threshold-based behavior (Schneider et al., 2023). This research aims to explore how the emergent linear correlation between precipitation and rockfall events is influenced by the temporal scale of data analysis through the development of a simulation model incorporating daily precipitation values and corresponding rockfall volumes based on designated thresholds. By simulating scenarios across various hypothetical rock slopes, insights can be derived regarding the interplay between precipitation and rockfall occurrences on day-to-day basis and what would be observed over longer time scales.
Application of Machine Learning Algorithms for Minerals Volume Prediction in Unconventional Reservoirs Using Conventional Well Logs
Authors: Bettir N. , Mellal I. , Dehdouh A. , Rabiei M. , Malki M. L. , Allam L. 
Published: August 2024

ABSTRACT:
Quantifying mineral volumes is crucial for accurate characterization of complex and unconventional reservoirs. Multimineral analysis is a technique used to estimate the fractions of minerals and fluids present in a reservoir based on measurements obtained from well logs. This approach assumes that the log response at each depth can be represented as a linear combination of the individual responses of different logging tools to each constituent, with each component weighted by its relative volume fraction. Achieving accurate mineral quantification necessitates having the number of well logs equal to or greater than the number of minerals in the reservoir. However, in complex reservoirs, there are situations where the number of well logs falls short of the number of minerals, resulting in an underdetermined system of linear equations. In such cases, accurate mineral quantification becomes challenging. To address this challenge, we propose the application of machine learning algorithms to predict mineral volumes using quad combo logs, which include gamma ray, deep resistivity, bulk density, and neutron porosity measurements. Four machine learning algorithms — Artificial Neural Networks (ANN), Random Forest (RF), Adaptive Boosting (AdaBoost), and Support Vector Regressor (SVR) — were utilized to generate predictions for mineral volumes. The performance of each machine learning model was assessed using regression statistical measures. RF delivered the best performance with a correlation coefficient of 0.76. Other algorithms yielded correlation coefficients between 0.11 and 0.54 with the SVR having the lowest value. The results show that this approach offers a promising solution for accurate mineral volume estimation in cases where the number of well logs is insufficient compared to the number of minerals in the reservoir.

1. INTRODUCTION
Petrophysical multimineral analysis is indispensable for the effective development of petroleum resources and accurate reservoir characterization. A detailed analysis entails accurate identification of the mineralogical composition as any misinterpretation in mineralogy can significantly impact various processes, spanning from geophysical interpretation to reservoir assessment (Cinintia Finahsan et al., 2014; Klenner et al., 2016).
Búzios Field: Coupled Model to Face the Geomechanical Challenges of the Giant Carbonate Offshore Field
Authors: Falcão F. O. L. , Cordovil A. G. , Maria A. L. M. , Orrico G. , Fidalgo B. , Parcero M. , Alves A. , Fernandes L. F. 
Published: August 2024

ABSTRACT:
The Búzios Field, located in the Santos Basin, is a vast offshore pre-salt reservoir with significant oil production potential. Spanning an area of 852 km2 at a water depth of 2000 meters, it lies beneath a 2000 m layer of salt and a 1000 m interval of post-salt sediments. Commerciality was declared in 2013, following its discovery in 2010. To understand the geomechanical effects due to reservoir production, factors such as fault behavior, compaction, subsidence, deformations, and compressibility were considered. A one-way coupling procedure using the GeomecBR, Petrobras' in-house software, assessed the geomechanical response. The developed geomechanical model covered an area of 145 km × 145 km and a vertical length of approximately 10 km, comprising over 50 million elements. It integrated various data and disciplines, involving a multidisciplinary team to calibrate the model and enhance the reliability of future forecasts. This paper outlines the methodology used to construct the geomechanical model for the Búzios Field and highlights its key findings. Understanding the geomechanical behavior improves the safety and efficiency of production operations and contributes to the broader understanding of pre-salt reservoirs in the Santos Basin.

1. INTRODUCTION
Búzios Field, located in the Santos Basin approximately 180 km off the coast of Rio de Janeiro, is a giant pre-salt carbonate reservoir. It covers an area of 852 km2 and has an average net pay of 400 m. Situated at a water depth of 2000 meters, the field is below 2000 m of salt and 1000 m of post-salt sediments. Discovered in 2010, it was declared commercially viable in 2013 after seismic acquisition and testing. With excellent oil production potential and strong reservoir communication, Búzios Field has proven to be a significant asset for Petrobras (Rosa, 2022).
The field is divided into 12 moduli, each produced by a Floating Production Storage and Offloading unit (FPSO). Five FPSOs have already been installed, each with a processing capacity of 150 kbpd. Notably, four of these FPSOs were deployed in less than two years, enabling it to reach the record of 600 kbpd of production in this period. By 2028, when the field will be fully developed with over 170 wells, the total processing capacity is expected to exceed 2 million boed (barrels of equivalent oil per day).