نشریه علوم و فنون سازندگی
سال چهارم شماره 3 (پیاپی 13، پاییز 1402)

Optimisation of short-term open-pit mining production scheduling is defined as the sequence of block extraction under the limitation of slope and capacities based on minimum production goals deviations. The NPV Scheduler software is a widely used application that addresses this challenge. However, it may not always reach an optimal solution due to using a heuristic algorithm and focus on maximizing discounted cash flow. Additionally, employing a stockpile to blend materials to create a suitable feed for the processing plant can lead to rehandling costs and various disadvantages. In this paper, we propose an optimization model for short-term production scheduling. Our model includes constraints that account for production goal deviations, allowing decision variables to adjust for any deviations that may occur. In the objective function, there is the cost of deviation multiplied by the amount of deviation plus the operating costs (transportation, extraction, etc.). The objective function goal is minimising deviation from production goals and also operating costs. This MIP model was solved using the CPLEX solver in the GAMS software. After two hours and 51 minutes, with a relative gap of 0.07%, a block extraction sequence for each three-month period was obtained without deviation from production goals. Subsequently, using the sequence obtained from the first three-month period, production planning was carried out for 12 weeks. This planning was done without considering transportation costs, and the deviations from production goals and the objective function for all 12 periods are zero.

Baichebagh mine was considered one of the most important mines in the region in the past, and the facilities established there confirm this fact. This mine has 4 areas named Talat, Taydian, Khoshnoudi and Darreh, The main problem in this mine is the lack of an optimal underground mining method from a technical and economic point of view. In this research, using qualitative and quantitative models of mining method selection, mining methods with primary priority were selected. The mining methods selected by quantitative and qualitative models were compared in terms of technical criteria such as the geometric and geomechanical conditions of the deposit, side properties of the deposit, etc. and finally 6 mining methods entered the stage of economic comparison. The mining methods selected in the economic comparison stage were compared with each other by analyzing the costs and direct revenues of the deposit extraction, and finally, the shrinkage stoping method was selected as the appropriate option from the technical and economic point of view. In order to analyze the stability of the stope and tunnel 60 in the shrinkage stoping method of Baichebagh mine, the pillar above tunnel 60 with a height of 3, 2 and 1 meters were compared with each other and after numerical modeling of each of the said pillars and drilling and filling the stope with ore and Comparing with the experimental relations, 1 meter pillar was chosen as the optimal pillar height above the tunnel 60.

Structures and offshore platforms are among the most crucial facilities for oil and gas extraction, playing a significant role in meeting the ever-increasing global energy demand. Monitoring the health of these structures not only ensures their operational efficiency throughout their lifespan but also allows for timely corrective actions such as repairs and strengthening, thereby extending their operational life. In this research, we aim to investigate the geometric deformations of the Salman offshore platform complex using satellite interferometry radar and Sentinel-1 synthetic aperture radar imagery. In the study area, two main challenges exist: topographic data modeling and atmospheric correction. To overcome the first challenge, an elevation model of the Salman platforms was created using radar interferometry techniques and available vector data, serving as input for the atmospheric correction stage. To address atmospheric corrections, the phase delay associated with the atmosphere was divided into two parts: the ionosphere and troposphere. In the ionosphere section, the total electron content was extracted from satellite-based position determination station data, and the phase delay associated with it was calculated and subtracted from the initial phase. For the tropospheric phase delay, precipitable water vapor data from the MODIS sensor were utilized and combined within a unified framework to calculate the phase delay. The results showed that the Salman platform complex experienced approximately a 12-centimeter subsidence from October 30, 2017, to April 2, 2023, equivalent to around 2.21 centimeters per year. This subsidence affected an average of 8 platforms within this complex.

The investigation of the quality of heterogeneous carbonate reservoirs typically involves a comprehensive analysis of the impact of the inherent properties of the rock and environmental factors on the rock-physical parameters of the reservoirs. This involves a microscopic and macroscopic examination of carbonate rocks to evaluate geological factors, which is then confirmed through rock physics relationships. Such an approach provides an acceptable estimate of the physical and mechanical condition of limestone, without the need for extensive physical testing or mechanical requirements. It is important to note that the physical and mechanical properties of stones are dependent on their texture and lithological composition. These characteristics are crucial for understanding the environment and conditions of formation of the stones and provide essential information for engineering designs. As part of the research project, which aims to integrate and validate various results related to exploration, development and management of hydrocarbon reservoirs, forming a database of the results of geological, petrophysical, and rock physics studies is a critical step. This creates a comprehensive database of reservoir information for many hydrocarbon fields under study, which can be utilized for future plans and projects related to the exploration and development of hydrocarbon fields in the country.

The present study investigates the impact of sulfate attack on the durability of reinforced ‎cement composites containing steel and polypropylene fibers, as well as silica nanoparticles. ‎To this end, varying weight percentages (1%, 2%, and 3%) of silica nanoparticles replaced ‎cement, and 1% by weight of steel fibers and 0.2% by weight of polypropylene fibers were ‎separately and concurrently added as micro-scale additives to the cement composite exposed ‎to sulfate attack. Consequently, the formulated cement composites underwent a 6-month ‎exposure to a 5% sodium sulfate solution, and the effects of the sulfate environment on ‎changes in compressive strength, weight, and longitudinal expansion of the specimens were ‎studied. The results indicate that the simultaneous presence of silica nanoparticles, steel ‎fibers, and polypropylene leads to increased durability against sulfate attack. Specifically, ‎the composite with 2% silica nanoparticles, 1% steel fibers, and 0.2% polypropylene fibers ‎exhibited the least reduction in compressive strength, mass loss, and longitudinal expansion ‎after 6 months of immersion in the sulfate solution compared to other formulations. ‎According to the findings, the concurrent presence of silica nanoparticles and steel and ‎polypropylene fibers in the cement matrix significantly enhances the durability of cement-‎based composites against sulfate attack.‎

Drilling of oil and gas wells is one of the most important operations in obtaining hydrocarbon reservoirs, which directly affects production costs. The success of this operation is dependent on the knowledge of the subsurface structures of the drilling path. Seismic data are one of the most important sources of information for understanding subsurface structures. Insufficient quality of seismic data leads to uncertainty in the interpreted horizons which can lead to drilling problems. This research was conducted with the aim of investigating the role of fault in the occurrence of drilling problems. For this purpose, the data of one well located in one of the oil fields in southwestern Iran have been collected. Investigations of daily drilling and geological reports and its correspondence with structural interpretations showed that the role of structural uncertainties in the occurrence of drilling problems was quite significant. The investigations shows that significant time and lost circulation material (LCS) valum have been used for solving mud loss, gain, and tight hole problem. Due to the similarity of this structural pattern with the conditions of most of the oil fields of Dezful embeyment, the operational solutions of these problem are presented as problem-oriented, result-oriented, geological-oriented and structure-oriented to be used in similar projects.