Podzemni radovi

INTERPRETATION OF TRANSIENT CAVING DUST PATTERNS DURING SEQUENTIAL CAVING OPERATION IN LTCC FACE

2025-08-04T16:13:51+00:00

Longwall top coal caving (LTCC) is a new mining technology introduced in Australia for enhancing the coal production rate by using the top coal caving operations. Though LTCC mine increase the coal production rates, they are more prone to high dust exposures and can create hazardous conditions for the underground coal mine operators. It is also necessary to introduce better dust control technologies and strategies during LTCC operations. For developing top coal caving dust control strategies, it is necessary first to develop fundamental understanding of transient caving dust flow pattern across the LTCC face. In this paper an attempt is made to predict respirable dust flow patterns during the sequential caving operation using Computational Fluid Dynamics (CFD) techniques. Numerical results predicted dust entering the downstream chock and disperses into the walkway region within 5 seconds of Respirable dust concentrations in the walkway of the first downstream caving chock in sequence caving are above 2mg/m³. Respirable dust concentrations in the walkway of the second downstream caving chock in the sequence and in the further downstream chocks are above 2.5mg/m³ and above.

DELIQUIFICATION TECHNIQUES AND PREVENTION A CASE STUDY FOR THE SOUTHERN PANNONIAN BASIN

2025-08-02T19:45:55+00:00

Liquid loading in gas wells leads to production challenges and decreases the overall recovery from these wells. Gas wells affected by liquid loading struggle to eliminate the liquid that accompanies the produced gas from the wellbore. The primary cause of liquid loading is a low gas flow rate or gas velocity. When the gas velocity falls below the critical threshold needed to transport liquid to the surface, the liquid begins to accumulate in the vertical section of a well, the lateral section of a horizontal well, and even within hydraulic fractures. Another indication of liquid loading is the high casing over tubing pressure. The focus of the case study on an onshore gas well is addressing the issue of liquid loading in Southern Pannonian Basin conditions. A well was selected that experienced a gradual decline in production and head pressure. A model was created using PipeSim software, followed by a sensitivity analysis under various operational scenarios. The significance of this study lies in optimizing the well parameters to prevent the occurrence of liquid loading. The paper is structured around relevant works, background, case study, methodology, results, and conclusions.

COMPARATIVE ANALYSIS OF SURFACE INFRASTRUCTURE MODELS FOR AN OIL FIELD IN THE PANNONIAN BASIN: EVALUATION OF ASPEN HYSYS AND GAP SOFTWARE

2025-08-02T19:46:31+00:00

The Integrated Production Model (IPM) acts as a digital twin of the actual field, representing reservoir behavior, all wells and their equipment, as well as the entire surface infrastructure. This model allows for changes in parameters within the virtual environment, enabling the simulation of various scenarios to determine how these changes affect the entire system. Consequently, it is possible to select the most optimal scenario and validate its impacts.

The development of the surface infrastructure model represents the final step in integrated production modeling, and this study focuses on creating a surface infrastructure model of an oil field in the Pannonian Basin using two software tools: Aspen HYSYS and Petroleum Experts - GAP. The goal is to compare the results obtained and identify the advantages and limitations of these software solutions. This analysis offers valuable insights into the capabilities of each program in simulating and optimizing oil operations.

Engineers use a range of computational strategies and mathematical models to design and operate processing facilities. Aspen HYSYS is a widely recognized tool in the oil and gas industry for process simulation, allowing engineers to model various operational scenarios in detail and assess their impact on system performance. Aspen HYSYS is used for modeling the entire production process, including oil and gas processing, refining, and chemical plants, while GAP specializes in integrated asset modeling (IAM), modeling wells, flowlines, risers, and surface facilities, optimizing the entire production system from the reservoir to the processing plant.

This paper first provides the theoretical background relevant to the research topic, including the basic concepts of process simulation in Aspen HYSYS and GAP. Following that, the research methodology is presented, including the steps of simulation and analysis. Finally, the simulation results are discussed, and conclusions are drawn regarding the applicability of both software tools for modeling surface infrastructure in oil fields.

PROSPER AND PIPESIM SOFTWARE FOR MODELING OF WELLS EQUIPPED WITH ESP SYSTEMS

2025-08-02T19:47:03+00:00

When the pressure at the bottom of the well is insufficient to overcome the total pressure losses from the bottom of the well to the separator, production using reservoir energy is no longer possible, and the well ceases to naturally flow. To enable fluid production from the well again, it is necessary to apply some artificial lift systems. The most applicable artificial lift methods are gas lift (GL), sucker rod pumps (SRP), electric submersible pumps (ESP), progressive cavity pumps (PCP), and hydraulic pumps (HP).

This paper will delve into the modeling of wells equipped with electric submersible pump (ESP) systems, which are a widely adopted artificial lift methods in the oil and gas industry. This research aims to create accurate models that reflect the performance of these systems. For the modeling we will use industry standard software Prosper and Pipesim and perform a comparative study between both. Study will aim to show advantages and disadvantages of using both software, contributing to the understanding of their applicability in optimizing ESP system performance. Ultimately, this work seeks to enhance the knowledge base regarding effective exploitation methods in hydrocarbon extraction.

We begin by explaining the cessation of the well's natural flow, followed by a transition to an artificial lift method. The second section focuses on the methodology, explaining how each software Pipesim and Prosper employs specific empirical formulas and correlations for modeling, and how they use nodal analysis to predict the well's behavior. The final part of the paper presents an actual case study in which the output data from both software programs are compared with the actual field-collected data from the ESP-equipped Well-X-1. Additionally, this analysis offers valuable insights into the strengths and limitations of using both Prosper and Pipesim, contributing to a deeper understanding of their applicability in optimizing ESP system performance. Ultimately, this study aims to enhance the knowledge base on effective exploitation methods in hydrocarbon extraction.

CORROSION RESISTANCE of X12CrMoWVNbN10-1-1 STEEL in NaCl SOLUTIONS at DIFFERENT pH VALUES

2025-08-02T19:47:35+00:00

The influence of pH on the corrosion behavior of X12CrMoWVNbN10-1-1 steel was examined in 0.1 M NaCl solution. The rate of general (uniform) corrosion of the tested steel was determined using linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) methods. In the NaCl solution with a pH of 2.9, the tested steel exhibited a more negative corrosion potential and lower corrosion resistance. Significantly higher corrosion potential and resistance to general corrosion were observed in a neutral solution (pH = 6.5), where the steel was in a passive state.

THEORETICAL FUNDAMENTALS OF CHEMICAL REACTIONS IN THE SOLID PHASE

2025-08-02T19:48:10+00:00

Chemical reactions in the solid phase are characterized by many specificities. The study of such reactions, with regard to the condensed state, eliminates the need to introduce many approximations that are common when considering reactions in the liquid phase or heterogeneous reactions, other laws, specific and inherent only to the solid state of matter. These make the scientific field of solid-state chemistry far more complex, due to the very strong need for a comprehensive multidisciplinary approach. The basic theoretical principles from the fields of physics, chemistry, physical chemistry and chemical technology are equally important. Any scientific consideration of chemical reactions in the solid phase, and especially defining the kinetics and mechanism of those reactions, implies the application of modern scientific achievements in the field of mechanics, crystallography, chemical thermodynamics, chemical kinetics, physical electronics, etc.

URANIUM(VI) ADSORPTION ON NATURAL AND MODIFIED CLINOPTILOLITE MINERAL

2025-08-02T19:48:39+00:00

In this paper the investigation results of adsorption of uranyl ion on unmodified and acid modified clinoptilolite are presented. Adsorption was investigated at different amounts of adsorbents in suspension, different concentrations of uranyl ion in solution, as well as at different pH values.

TREATMENT OF FLUE GAS AND COAL TO REDUCE AIR POLLUTION-OVERVIEW

2025-08-02T19:49:23+00:00

This paper presents the procedures that can be used to reduce air pollution that originates from the burning of fossil fuels. Research has shown that burning coal is the largest source of emissions of greenhouse gases such as carbon dioxide, sulfur oxides, nitrogen oxides and suspended particles. In order to reduce the emission of harmful agents from thermal power plants, several procedures based on various technologies are applied. It is possible to treat the already created flue gases created by burning coal in the classic way, treatment of the coal itself before the start of combustion in the thermal power plant and special procedures for coal treatment. Very effective procedures applied to protect air from pollution in the energy sector are: flue gas desulphurization (FGD), coal purification before the combustion process (coal washing), coal gasification and coal combustion in a fluidized bed.

METHODOLOGY FOR DIMENSIONING THE HOISTING SHAFT USING MATHEMATICAL AND GRAPHICAL METHODS

2025-08-02T19:49:51+00:00

The opening of deep ore bodies is most rapidly accomplished using vertical shafts. Shaft construction is the most economically demanding process, so despite providing the fastest access to deep ore bodies, the high capital costs involved in construction mean that determining the cross-sectional dimensions of the shaft is a complex and very important step in the design of the shaft and the entire underground mine. An inadequate cross-sectional area can have negative impacts: a small area limits the mine's capacity, while a large area increases construction costs and affects shaft stability. In modern mining practice, shafts are mostly constructed with a circular cross-section, whose area depends on a single parameter - shaft diameter. The choice of area, or more specifically the minimum shaft diameter, is generally determined empirically using mathematical or graphical methods. If there are indications that production capacity might increase or that greater volumes of air will be required, adjustments are made, and the shaft diameter is increased. This paper will present an extended mathematical model and calculations to accurately determine the dimensions of skips for ore hoisting, followed by a graphical method for determining the shaft diameter based on the mathematical calculation.

APPLICATION OF SMALL SELF-PROPELLED DRILL RIGS

2025-08-02T19:50:22+00:00

Small-diameter drilling is used in many civil and mining engineering areas. In the past, it was mainly done with hand-held hammer drills. Still, the need for safer and more efficient work has led to the development of small self-propelled drilling machines that require fewer workers for the same capacity and provide significantly safer work.

Drilling small-diameter boreholes is used for some special blasting methods (blasting in urban areas, secondary blasting of boulders, etc.), to make boreholes during the exploitation of decorative stone blocks, to place anchors in slope stabilization, to mine underground, to apply expansive mixtures for the disintegration of solid masses (stone, concrete), to make protective screens, to tunnel, etc.

Several manufacturers manufacture small self-propelled drill rigs, all of which are equipped with remote controls. Thus, the operator is not forced to stand in potentially unsafe places compared to someone working with a hand-held hammer drill. The paper will present the possibilities and methods of applying these drill machines to different working conditions.

PLANNING THE OPERATION OF Li-ION BATTERY-POWERED TRUCKS

2025-08-02T19:50:56+00:00

This paper analyses the planning of operation for underground mining trucks powered by lithium-ion batteries. Trucks supplied by the companies Epiroc and Sandvik are used as examples, comparing their characteristics with equivalent diesel-engine models. These trucks have similar payload capacities and dimensions, but significant differences in available energy, demonstrating that battery-powered trucks have substantially lower autonomy. The paper describes a method for estimating the autonomy of battery-powered trucks, taking into account motor efficiency, energy losses, and regenerative braking. A procedure is presented for determining the energy consumption for truck movement along a known route, considering the total resistance. It is demonstrated that the lower available energy of battery-powered trucks is a major factor necessitating a different approach to planning their operation in underground mining.

A-PRIORI ACCURACY ASSESSMENT OF TRACING THE CUT-TROUGH IN THE VERTICAL PLANE DURING THE CONSTRUCTION OF THE HOULAGE DRIFT IN THE ''GROT'' MINE

2025-08-02T19:51:40+00:00

Mining projects for the exploitation of the grade ores encompass specific technical and technological solutions that are a consequence of the characteristic spatial position and geometry of the ore deposit, existing mining works, natural and artificial objects, and terrain relief. To realize the mining project, a series of mining and surveying tasks must be carried out in the pre-project and project phases of exploitation, as well as during the construction of mine facilities and the excavation of mineral materials. Among the various mining and surveying tasks that follow project implementation, the tracing of the cut-through or cross-cuts, between existing mine tasks is often a crucial step. For the successful execution of these tasks, it is necessary to perform an a priori assessment of the accuracy of the cut-through in order to define the required precision for the measurement/monitoring process, and based on that, determine the appropriate ecqiupment and measurement method. This paper presents an a priori assessment of the accuracy of marking the cut-through in the vertical plane during the construction of the houlage drift on the IX horizon of the "Grot" lead and zinc mine.