Rock Parameters Research Articles

The values of primary stresses are not allowed for as a criterion in the selection of roof bolting systems in mining excavations located at various depths in Polish copper ore mines. Therefore, in order to ensure enduring and safe operation of excavations, in particular, those driven in unfavourable geological and mining conditions, this problem has required solutions based on numerical methods. This article presents an example of applying numerical simulations to the evaluation of the stability of headings in Polish copper ore mines. The analyses included mining excavations located at various depths in the rock mass. This issue is of great importance, as safety regulations are prioritised in mining excavations which remain in operation even for several decades. The stability of the headings was evaluated with the use of the RS2 specialist numerical simulation software. This computer program uses the finite element method (FEM) for calculations. The rock parameters used in the numerical models have been determined on the basis of the Hoek–Brown classification. For that purpose, the RocLab 1.0 software was used. The parameters of the stress field were identified from the profile of the GG-1 shaft with the assumed hydrostatic state of stress. The numerical modelling was performed in a triaxial stress state and in a plane strain state. The numerical analyses were based on the Mohr–Coulomb failure criterion. The rock medium was described with the elastic-plastic model with softening (roof and walls) and with the elastic-plastic model (floor). The results of the numerical analyses served to provide an example of the application of a roof bolting system to protect headings located at the depths of 1000 m b.g.l. and 1300 m b.g.l.

One-Dimensional Rock and Soil Characteristic Parameters Prediction Method Based on SRR

Disc cutter wear has emerged as a critical concern impacting the efficiency and cost budgets of TBMs (tunnel boring machines). Through statistical analysis of field data on cutter wear in a TBM tunnel, this study explores the wear rules of different types of disc cutters in granite. Grey sensitivity analysis is employed to investigate the sensitivity between the cutter ring wear rate of face cutters and two types of cutter wear influence parameters. Subsequently, reasonable parameters are selected to develop a new cutter life prediction model for face cutters. The results show that, with increases in the installation radius, the accumulated wear extent shows a linearly increasing trend for both the center and the face cutter, while it first increases and then decreases for gauge cutters, and the accumulated replacement number shows a linear growth trend for face cutters. The accumulated wear extent of the average single cutter position of gauge cutters is about 3 times that of face cutters and 7 times that of center cutters; the number of replaced cutter rings of the average single cutter position for gauge cutters is about 3–4 times that for center cutters and face cutters; and the average utilization rate of gauge cutters is the highest (80.97%). The cutter ring wear rate of face cutters is the most sensitive to three intact rock parameters (uniaxial compressive strength (UCS), Cerchar abrasion index (CAI), and equivalent quartz content (EQC)) and two TBM tunnelling parameters (cutterhead thrust (F) and cutterhead rotational speed (RPM)). Finally, a new cutter life prediction model (R2 = 0.964) for face cutters is developed based on F, UCS, and RPM. The research results can provide a certain theoretical basis for cutter wear and cutter life prediction for the face cutters of TBM projects in similar geological conditions and TBM specifications.

Research on the Back-Analysis of Tunnel Surrounding Rock Deformation Considering the Deterioration Effect of Surrounding Rock Parameters

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 23381, “Machine-Learning-Assisted Prediction of Electrical Properties for Heterogeneous Reservoirs: Case Study in Mamey Field, Northern Colombia,” by Carelis Moya, Hocol; Roxiris C. Prado, Halliburton; and Hugo Caycedo, Hocol, et al. The paper has not been peer reviewed. Copyright 2024 International Petroleum Technology Conference. _ Petrophysical characterization in reservoirs with high heterogeneity is a consistent challenge. The case study presented in the complete paper describes a machine-learning (ML) technique to determine electrical properties. The methodology combines logs, rock types, and facies and digital core analyses from the Mamey field in northern Colombia, a reservoir composed of interlaminated mudstones and very-fine to fine sandstones enclosed in a deltaic environment and capped by cross-stratification sandstones associated with incised valley deposits. The results obtained indicate that the technique is feasible for estimating a continuous curve of the Archie parameters m and n associated with the textural changes identified in images and computed tomography. Introduction For many years, the industry has reviewed easily extracted reservoirs and neglected those that were slightly more complex. Rock parameters were obtained from conventional core analysis using Archie’s cementation coefficient (m) and saturation exponent (n) used in petrophysical analysis, parameters that were difficult to pin down, especially in complex reservoirs because of rock typing, facies, stratigraphy, and structural variations. The authors’ study was used to supplement the petrophysical model and was focused on reserves estimation according to a water-saturation model, with m and n obtained from digital and conventional rock analysis. The method involved an ML technique using logs (triple-combination, sonic, petrophysical curves, microresist images, facies, and rock type) to obtain m and n. Geological Background The Saman field is in the northwestern part of the Lower Magdalena Valley (LMV) Basin. The petroleum system in this region is linked closely to the Oligocene and Neogene sequences. The key reservoirs include the Cienaga de Oro (CDO), Chengue, and Lower Porquero formations. Within the LMV, the CDO represents an Oligocene/Miocene sequence associated with a transgressive system originating from shallow marine environments. The shoreline is interpreted as having undergone a west-to-east movement, effectively filling ancient basement topography, particularly in the San Jorge and Plato depocenters. Detailed core interpretations in Saman reveal the presence of deltaic facies within the CDO, which notably prograde toward the northwest.

Exploring the prospects of deep natural gas resources from the geochemical parameters of the Shahejie Formation source rocks in the Banqiao depression

Shear wave velocity model using HVSR inversion beneath Bandar Lampung City

Investigation on the failure mechanism for surrounding rock in small interval tunnels using finite element limit analysis method

In order to analyze the stability of the bridge above the goaf, the disturbance influence of goaf residual deformation on the bridge is studied. Firstly, an equivalent numerical simulation method of goaf residual deformation evolution process is studied by quantitative analysis the sensitivity of residual subsidence to the rock parameters using the OAT (one-variable-at-a-time). Then, the collaborative deformation of ground, pile, and bridge floor is studied under the condition of a simply-supported beam bridge above the goaf center. Finally, the mechanism of collaborative deformation of ground, pile, and bridge floor is revealed. The results show that the goaf residual deformation process can be obtained by weakening the elastic modulus of fractured rock in the caving zone. At the final residual deformation stage, the subsidence ratio of ground to pile is about 10, and the subsidence ratio of pile to bridge floor is about 2, while the ground horizontal movement ratio of ground to pile is about 7, and the bridge floor horizontal movement can be ignored. The bridge floor is always in the positive curvature influence zone, and the pile has an inhibitory effect on the curvature deformation of the bridge floor. The compression deformation occurs between the piles locations, while the tensile deformation occurs at the pile location. The evolution of negative frictional resistance derived from goaf residual deformation is the main reason for the change in the collaborative deformation law among the ground, pile and bridge floor. This research can provide scientific support and theoretical basis for the design, construction, and protection of the bridge above the goaf center, and can also provide reference for the stability evaluation of bridge above goaf under other conditions.

Coupling Upscaled Discrete Fracture Matrix and Apparent Permeability Modelling in DFNWORKS for Shale Reservoir Simulation

Abstract Earthquakes occur when tectonic stresses develop deep within the Earth. In the earthquake zone, the rocks are igneous, including gabbro. Gabbro rocks produce electron–hole pairs under tectonic stresses. These holes flow in the volume of gabbro rock under tectonic pressures and cause changes in electric charge and as a result, produce variable electric and magnetic fields that lead to a signal of electromagnetic waves at the place of pressure. This electromagnetic signal is received on the surface of the Earth after passing through different layers of the Earth. In this work, by applying uniaxial hydraulic pressure on the gabbro rock, a new physical model similar to an earthquake is presented, which by receiving and monitoring electromagnetic signals, can help to investigate the tectonic changes in the Earth. By utilizing the electrical and optical parameters, the intensity of the electromagnetic signal of the earthquake created on the Earth's surface is calculated.

Район находится на южной окраине Тенизской впадины. Он относится к известной рудной провинции – Центральному Казахстану. Разнообразие полиметаллических оруденений в районе связано с полифациальностью магматических образований Сарысу-Тенизского поднятия. Выбор оптимальных для решения геопрогнозных задач методов разведочной геофизики, оценка уровня их геологической информативности осуществляются детальным изучением петрофизических параметров горных пород по территории исследования. Проведены сбор и анализ большого объема геологических и петрофизических сведений. По диапазонам изменения значений свойств выполнено группирование горных пород. Таких групп по значениям плотностей – 6. По магнитной восприимчивости горные породы разделены на 4 группы – от немагнитных до сильномагнитных. Результаты систематизации данных по физическим свойствам позволяют прогнозировать состав источников гравимагнитных аномалий Аудан Теңіз ойысының оңтүстік шетінде орналасқан, белгілі рудалы провинцияға – Орталық Қазақстанға жатады. Аудандағы полиметаллды минералданудың әртүрлілігі Сарысу-Теңіз көтерілімінде магмалық түзілімдердің полифациялы болуымен байланысты. Геологиялық болжауды орындау үшін геофизикалық әдістерді таңдау және олардың геологиялық мәліметтілігін бағалау таужыныстардың петрофизикалық параметрлерін терең зерттеулер арқылы орындалады. Сондықтан геологиялық, петрофизикалық мәліметтердің үлкен көлемі жинақталды және талданды. Құрылымның қимасындағы таужыныстар тығыздығы мен магниттік қасиеттерінің өзгеру аралықтары бойынша топтастырылды. Тығыздық мәндері бойынша ауданындағы таужыныстар 6 топтан тұрады. Таужыныстардың магнит қабылдағыштығы бойынша 4 топқа бөлінді: магнитсізден бастап, магниттілігі күшті таужыныстарға дейін. Физикалық қасиеттер туралы мәліметтерді жүйелеу нәтижелері гравимагниттік аномалиялар көздерінің табиғатын болжауға мүмкіндік береді The area is located on the southern outskirts of the Teniz Basin and is part of the renowned ore province of Central Kazakhstan. The diversity of polymetallic ore occurrences in the region is linked to the polyfacial nature of the magmatic formations of the Sarysu-Teniz Uplift. The selection of optimal methods for exploratory geophysics to address geopredictive tasks, along with the assessment of their geological informativeness, is carried out through a detailed study of the petrophysical parameters of rocks across the research territory. A substantial amount of geological and petrophysical data has been collected and analyzed. Rocks have been grouped based on the range of property values: six groups were formed based on density values, and the rocks were divided into four groups based on magnetic susceptibility, from non-magnetic to highly magnetic. The systematic organization of data on physical properties allows for the prediction of the composition of sources of gravimagnetic anomalies

Forecasting chaotic behavior of the drill bit in real-time using a DNN model integrated with rock surface morphology

The thermal structure of the Colombian lithosphere: A regional and basin-scale analysis

As deep oil and gas resources and Carbon Capture and Storage (CCS) are developed, enhancing drilling efficiency in hard rock formations has emerged as a critical technology in oil and gas extraction. The advancement of ultrasonic, high-frequency vibration rock-breaking technology significantly facilitates efficient rock crushing. When subjected to ultrasonic high-frequency vibrations, the rock’s response is a crucial issue in implementing ultrasonic vibration rock crushing technology. This study employed numerical simulation and theoretical deduction methods, utilizing a multi-physics approach that couples solid mechanics with pressure acoustics. It integrated information on common influencing parameters of ultrasonic generators and reservoir rock properties to establish model parameters, analyze simulation results, and perform theoretical deductions. The research investigated the response patterns of different-sized rock samples under high-frequency ultrasound vibration excitation across various frequencies, amplitudes, and confining pressure conditions. Through the development of a three-dimensional model and the application of principles from solid mechanics and elastoplasticity, the study derived equations that describe the resonance frequencies of rock blocks under confining pressure as functions of relevant rock parameters. The findings indicate that ultrasonic vibrations can effectively induce rock displacement. Under excitation frequency sources, the rock exhibits a natural frequency correlated with the rock sample size. When the excitation frequency approximates the natural frequency, the rock resonates. At this point, the rock’s surface displacement is maximal. The rock undergoes tensile stress, leading to stress concentration that facilitates rock damage and fragmentation. Increasing the excitation amplitude enhances rock crushing, as it amplifies the maximum surface displacement under the same frequency excitation. Confining pressure exerts an inhibitory effect on the rock’s vibration response, but it does not alter the resonance frequency of the rock sample, a fact verified by both numerical simulation and theoretical results. Based on the research findings in this paper, it can help to optimize the parameters of ultrasonic vibration rock breaking in field application to achieve the best rock-breaking effect.

The concept of volume fracturing has revolutionized the conventional limits of low permeability, expanded the effective resource space, and significantly enhanced oil well production in tight oil reservoir development. This paper elucidates the mechanism of volume fracturing technology for tight sandstone reservoirs by considering multiple factors such as the initiation range of multi-fractures, influence of far-well horizontal principal stress on fracture initiation and propagation, degree of natural fractures development, and mechanical parameters of reservoir rock. Through simulation based on the mechanical parameters of reservoir rock, a comparative analysis was conducted between the model-calculated rock fracture pressure value and measured data from fracturing construction wells in the study area. The results revealed that there was a discrepancy within 10% between the model calculations and actual data. By simulating the effects of different injection volumes of fracturing fluid, pumping rates, and perforation methods on the fracture geometry, optimal design parameters for volume fracturing technology were obtained. Additionally, we propose optimization ideas and suggestions for construction parameters applicable to field operations. The simulation results indicate that a minimum recommended fluid volume scale exceeding 1800 m3 is advised for the reservoir. Based on frictional calculations, it is recommended to have an on-site construction rate not less than 18.0 m3/min along with 36–48 holes/section for perforation purposes. The numerical simulation research presented in this paper provides a theoretical reference basis and practical guidance for the application of fracturing network technology in tight sandstone reservoirs.

To safely dispose of nuclear waste in underground facilities, engineered barrier systems are needed to seal shafts and galleries. The material used in these barriers must be adapted to the host rock parameters. Shrinking and cracking must be avoided to provide a barrier with almost zero permeability. For repositories in salt rock environments, several types of salt concrete (SC) are used. Within the project SealWasteSafe, we compared the performance of an innovative alkali-activated material (AAM) with standard SC in their hydration and hardening phase. To monitor the microstructural changes within the two materials SC and AAM, acoustic emission (AE) signals have been recorded for up to ~250 days on 340-liter-cubic specimens. The phenomenon of AE is defined as the emission of elastic waves in materials due to the release of localized internal energy. Such energy release can be caused by the nucleation of micro-fracture, e.g. in concrete while curing or when exposed to load. The occurrence of AE events gives first rough indications of microstructural changes and potentially occurring cracking and thus, provides insights for structural health monitoring (SHM). The results show, that for the first 28 days after casting, less AE activity was detected in the AAM compared to SC. After 61 days, in the AAM material, the number of AE events exceeded those observed in the SC. However, the majority of the AE detected in AAM was related to surface effects, and not to microstructural changes within the matrix. Additionally, the source location analysis indicated, that despite lower activity in SC, we observed some clustering of the events. In contrast, in AAM, the activity inside the specimen is randomly distributed over the whole volume. The monitoring results help to estimate the material’s sealing properties which are crucial to assess their applicability as sealing material for engineered barriers.

In this paper, the sensor is applied to the collection of rock parameter data. Aiming at the classification and evaluation of stability (i.e. rock quality), an attribute recognition model for the classification and evaluation of surrounding rock quality of underground engineering is established. Using multi-source data fusion and orthogonal numerical simulation test methods, the effects of rock mechanics parameters on the horizontal convergence of the tunnel, the settlement of the vault and the plastic zone coefficient are studied. Six factors (elastic modulus, Poisson’s ratio, internal friction angle, tensile strength, cohesion and density) and three levels of orthogonal experimental solutions were selected. The method of defining similar weight by using similar number to determine the weight of evaluation index, so as to calculate the comprehensive attribute measure, and apply confidence criteria to identify the stability of rock samples. Through the analysis and evaluation of rock mass quality classification of underground engineering, the application of the model and the evaluation method of rock mass quality classification are explained. The test results match the orthogonal test results; Considering the stability of tunnel envelope, the horizontal convergence, vault settlement and plastic zone coefficient after excavation should be comprehensively considered.

Problem Statement and Purpose. The problem of environmental pollution with various potentially dangerous substances and, first of all, heavy metals, the impact of which will be carried out for many years, is the most important for environmental geochemistry. Despite the material accumulated in the literature, the forms of finding and mobility of trace elements in soils remain insufficiently researched; forms of migration of chemical elements in soil solutions, natural waters, entry into vegetation. The study of heavy metals in biomass systems of urban areas and their ecological assessment require systematic, comprehensive research. Establishing the relationship between the content of chemical elements in vital natural environments for humans is of particular importance. The main purpose of this article is to study the patterns of distribution of trace elements in the main types of soils, vegetation and forms of their migration in natural waters, background and technogenically polluted areas of the Forest- Steppe Zone. Data & Methods. The measurement of the content of heavy metals in soil and natural water samples was performed using the method of mass spectrometry with inductively coupled plasma (ICP-MS) on the Element‑2 analyzer (Germany). The forms of microelements in soil samples were determined by the method of successive extractions. The forms of migration of trace elements in natural waters were determined using mathematical modeling methods using specialized software tools GEMs v.3.2 and Hydra&Medusa. Results. The regularities of the distribution of microelements in soils, natural waters, and vegetation in conditionally clean and technogenic landscapes of the Forest-steppe zone of Ukraine were studied. The distribution of microelements in soils is determined by their physical and chemical properties, mineralogical and geochemical parameters of soil-forming rocks, landscape and technogenica conditions of the studied territories. Analytical studies were conducted to determine the mobile forms of microelements in soil solutions. Data were obtained on the regularities of the distribution of heavy metals in the soils of conditionally clean territories and the natural park of the NNP «Nizhnyosulsky», as well as their content in the vegetation of park landscapes. The gross content of Pb, Cu, Ti, Cr, V in the soils of the studied territory of the NPP «Nizhnyosulsky» is higher than the background values. The bio-inert systems of technogenic landscapes of the city of Brovary and Kyiv landfill № 5 were studied. It was established that the emissions of industrial enterprises of various profiles significantly change the geochemical background of metals in the analyzed soils of the city of Brovary. In these soils, the content of heavy metals, which are in the exchangeable and easily exchangeable fractions, increases and their mobility increases compared to the background ones. The highest level of soil contamination is observed on the territory of landfill № 5. Using the method of thermodynamic modeling, data on the forms of migration of microelements in soil solutions of technogenically polluted soils, natural waters (surface and underground) were obtained. Migration of heavy metals in soil solutions is carried out mainly in the form of free cations and dissolved organometallic complexes. The increased content of Mn, Cu, Co, Fe in the dry residue of the surface water of landfill № 5 was determined, which does not meet the sanitary standards for the discharge of wastewater into open waters. Pollution of surface waters by sewage with a high content of primarily organic toxicants: nitrates, vchlorides, was also found. The peculiarities of the microelement composition of drinking groundwater in the territory of Korostyshiv district of Zhytomyr region were studied. The dynamics of changes in the amount of total mineralization, the content of ions Ca2+, Mg2+, SO42–, Cl– in the aquifer of the fractured zone of crystalline rocks and their weathering crust were analyzed. A high positive correlation was found between the concentrations of Mg2+, SO42–, Cl– and their normalized indicators by the amount of water withdrawal. The obtained results testify to the significant role of the anthropogenic factor in the formation of the chemical composition of the studied groundwater. A comparison of the biologically significant concentrations (BSC) of the main microelements of groundwater with their content in water samples determined during the study allowed us to identify peculiarities: in the studied waters, an excess of such elements as Sr and Ba is observed. Instead, insufficient amounts of elements such as Li, V, Mn, Co, Ni, Cu, Zn, As, Cd and Pb were found. Based on the obtained results, conclusions were made about the presence of risks of some trace element diseases in the studied territory.

Aiming at the shortcomings of the BP neural network in practical applications, such as easy to fall into local extremum and slow convergence speed, we optimized the initial weights and thresholds of the BP neural network using the particle swarm optimization (PSO). Additionally, cloud computing service, web technology, cloud database and numerical simulation were integrated to construct an intelligent feedback analysis cloud program for underground engineering safety monitoring based on the PSO-BP algorithm. The program could conveniently, quickly, and intelligently carry out numerical analysis of underground engineering and dynamic feedback analysis of surrounding rock parameters. The program was applied to the cloud inversion analysis of the surrounding rock parameters for the underground powerhouse of the Shuangjiangkou Hydropower Station. The calculated displacement simulated with the back-analyzed parameters matches the measured displacement very well. The posterior variance evaluation shows that the posterior error ratio is 0.045 and the small error probability is 0.999. The evaluation results indicate that the intelligent feedback analysis cloud program has high accuracy and can be applied to engineering practice.