انجمن ژئومکانیک نفت ایراننشریه ژئومکانیک و ژئوانرژی2538-46517420250120Three-Dimensional Reconstruction of Porous Media Images Using the Vox2Vox Model in Presence of Multi mineral Segmentation InformationThree-Dimensional Reconstruction of Porous Media Images Using the Vox2Vox Model in Presence of Multimineral Segmentation Information11321422510.22107/jpg.2025.436814.1226FAبهارهکشاورزدانشگاه آزاد اسلامی واحد علوم تحقیقات، دانشکده نفت و مهندسی شیمی، تهرانمحسنمسیحیاستاد مهندسی نفت دانشکده مهندسی شیمی نفت دانشگاه صنعتی شریفمستانهحاجی پور شیرازی فرددانشکده نفت و مهندسی شیمی، دانشگاه آزاد اسلامی واحد علوم و تحقیقات، تهران، ایرانابراهیمبی نیاز دلیجانیدانشکده نفت و مهندسی شیمی، دانشگاه آزاد اسلامی واحد علوم و تحقیقات، تهران، ایرانJournal Article20240127The evaluation of morphological, topological, statistical, and flow properties of porous media needs high-resolution images of porous media at the pore scale. However, direct access to high-quality tomographic images can be costly and impractical. Image reconstruction techniques offer a viable solution for obtaining visually realistic image data. Among these methods, deep learning-based approaches have gained significant attention from researchers. However, the utilization of petrographic information from porous media in training such models is rare.<br />In this study, we investigate the impact of incorporating multimineral segmentation information in the training of the VOX2VOX model. The data used in this model consists of 3D images of a sandstone reservoir along with segmented images into 5 classes, including macro-pores, clay, quartz, feldspar, and high-density minerals. Additionally, the Vox2Vox model has been trained with binary segmented images containing pores and solid phases to compare the effect of multimineral information on model and reconstructed images. Incorporating multi-mineral segmentation from the porous media significantly enhances the model's image reconstruction capabilities, as observed through comparisons of various dynamic and static features. Incorporating a five-class dataset has led the model to exhibit lower error at the outset of training, stabilizing after approximately 30 epochs, whereas this point for the model based on the two-class dataset is around 60 epochs. Furthermore, the comparison parameters for image quality, specifically SSIM Score: 0.95, MSE Score: 0.00013, and PSNR Score: 38.93, are observed for the first model, while for the second model, they are SSIM Score: 0.89, MSE Score: 0.00112, and PSNR Score: 29.49. The original image has a porosity of 0.229, which increases to 0.233 and 0.244 in the reconstructed images from the models based on five-class and two-class datasets, respectively. Additionally, the graphs of other parameters also demonstrate the superiority of the model based on the five-class dataset.The evaluation of morphological, topological, statistical, and flow properties of porous media needs high-resolution images of porous media at the pore scale. However, direct access to high-quality tomographic images can be costly and impractical. Image reconstruction techniques offer a viable solution for obtaining visually realistic image data. Among these methods, deep learning-based approaches have gained significant attention from researchers. However, the utilization of petrographic information from porous media in training such models is rare.<br />In this study, we investigate the impact of incorporating multimineral segmentation information in the training of the VOX2VOX model. The data used in this model consists of 3D images of a sandstone reservoir along with segmented images into 5 classes, including macro-pores, clay, quartz, feldspar, and high-density minerals. Additionally, the Vox2Vox model has been trained with binary segmented images containing pores and solid phases to compare the effect of multimineral information on model and reconstructed images. Incorporating multi-mineral segmentation from the porous media significantly enhances the model's image reconstruction capabilities, as observed through comparisons of various dynamic and static features. Incorporating a five-class dataset has led the model to exhibit lower error at the outset of training, stabilizing after approximately 30 epochs, whereas this point for the model based on the two-class dataset is around 60 epochs. Furthermore, the comparison parameters for image quality, specifically SSIM Score: 0.95, MSE Score: 0.00013, and PSNR Score: 38.93, are observed for the first model, while for the second model, they are SSIM Score: 0.89, MSE Score: 0.00112, and PSNR Score: 29.49. The original image has a porosity of 0.229, which increases to 0.233 and 0.244 in the reconstructed images from the models based on five-class and two-class datasets, respectively. Additionally, the graphs of other parameters also demonstrate the superiority of the model based on the five-class dataset.http://www.irpga-journal.ir/article_214225_be34bf66be06f57b0405367178805c7c.pdfانجمن ژئومکانیک نفت ایراننشریه ژئومکانیک و ژئوانرژی2538-46517420250120Estimating Pore Pressure and Minimum Horizontal Stress of An Oil Field Based on Well Log Data Using Newton Classical Optimization MethodEstimation of Pore Pressure and Minimum Horizontal Stress Using Newton Classical Optimization Procedure based on Well Log Data142521422810.22107/jpg.2025.440332.1227FAمنوچهرصانعیدانشگاه صنعتی شاهرود0000-0003-0869-1988احمدرمضان زادهدانشگاه صنعتی شاهرود0000-0001-5848-4229میناشفیع آبادیدانشگاه صنعتی شاهرودJournal Article20240127Optimization is one of the branches of applied mathematics used in various decision-making fields such as engineering, mathematics, and computer science. The classical method is one of the branches of optimization that can be used to make decisions in various problems. Accurate knowledge of pore pressure and minimum horizontal stress is necessary for the drilling, stability, and completion stages of the wellbore. The estimation of the mentioned parameters is generally obtained using empirical and analytical relationships. The answer to these equations is suitable when the constant coefficients chosen for each equation are correct. The computation of coefficients is usually done experimentally and even manually. Now, accurate and automatic computation of parameters can be a progressive step for using these equations. Therefore, the purpose of this research is presented in three parts. First, the pore pressure is estimated based on Eaton's relationship. To accurately estimate the pore pressure, the constant coefficients of the Eaton equation are automatically calibrated and calculated through the gradient-based Newton classical optimization method. Second, the minimum horizontal stress is obtained using the Blanton equation. To estimate properly the minimum horizontal stress, the constant coefficient of Blanton’s method is computed automatically via the Newton classical optimization method. Finally, the values of pore pressure and minimum horizontal stress are compared with the measured data to evaluate the accuracy of the results. These results show the ability of the proposed optimization method to determine accurately the pore pressure and the minimum horizontal stress.فشار منفذی یکی از مهمترین پارامترهای حفاری چاه، پایداری چاه، تکمیل، بهینه سازی و بهبود تولید مخزن است. بهینه سازی یکی از شاخه های ریاضیات کاربردی است که در زمینه های مختلف تصمیم گیری مانند مهندسی، ریاضیات و علوم کامپیوتر کاربرد دارد. روش کلاسیک یکی از شاخه های بهینه سازی است که می توان از آن برای تصمیم گیری در مسائل مختلف استفاده کرد. آگاهی دقیق از فشار منفذی و تنش افقی حداقل برای مراحل حفاری، پایداری و تکمیل چاه ضروری است. برآورد پارامترهای مذکور عموماً با استفاده از روابط تجربی و تحلیلی به دست می آیند. پاسخ این روابط زمانی مناسب است که مقدار ضرایب ثابت تعیین شده برای هر رابطه صحیح باشد. محاسبه ضرایب معمولاً به صورت تجربی و حتی دستی انجام می شود. اکنون محاسبه دقیق و خودکار پارامترها می تواند گامی پیش رونده برای استفاده از این روابط در صنعت باشد. بنابراین هدف این پژوهش در سه بخش ارائه شده است. ابتدا فشار منفذی بر اساس رابطه ایتون تخمین زده می شود. برای تخمین دقیق فشار منفذی، ثابت های معادله ایتون به طور خودکار کالیبره شده و از طریق روش بهینه سازی کلاسیک نیوتن مبتنی بر گرادیان محاسبه می شود. دوم اینکه تنش افقی حداقل با استفاده از معادله بلانتون به دست می آید. برای برآورد صحیح تنش افقی حداقل، پارامتر ثابت روش بلانتون از طریق روش بهینه‌سازی کلاسیک نیوتن محاسبه می‌شود. در نهایت، مقادیر فشار منفذی و تنش افقی حداقل با داده‌های اندازه‌گیری شده برای ارزیابی دقت نتایج مقایسه می‌شوند. این نتایج توانایی روش بهینه‌سازی پیشنهادی را در تعیین دقیق فشار منفذی و تنش افقی حداقل نشان می‌دهد.http://www.irpga-journal.ir/article_214228_d579381522717c9f7a131aa3b95dd16a.pdfانجمن ژئومکانیک نفت ایراننشریه ژئومکانیک و ژئوانرژی2538-465174202501202D Simulation of Shale Gas Reservoir through Z-Axis Tipper Electromagnetic Data2D Simulation of Shale Gas Reservoir through Z-Axis Tipper Electromagnetic Data263721340610.22107/jpg.2025.445823.1229FAمیثمعابدیدانشکده مهندسی معدن دانشگاه تهرانJournal Article20240226Shale gas, an unconventional natural gas resource abundant in organic matter, has gained significant attention in global natural gas exploration as a crucial supplement and alternative to conventional natural gas sources. Due to higher electrical resistivity of oil traps in conductive sedimentary backgrounds, shale gas reservoirs are ideal targets for geophysical studies to be explored, whereby the Z-axis tipper electromagnetic method (ZTEM) can be employed to simulate and model their geoelectrical responses. The study conducted involved the utilization of an airborne method, a tool that relies on natural source transmitter, to simulate shale gas reservoirs. Initially, geoelectrical models of shallow shale gas reservoirs were constructed for three different simple geological scenarios, followed by the generation of responses through an airborne geophysical survey. The assumed electrical resistivity models were effectively reconstructed by applying an inversion algorithm to the data. This process proved to be successful in accurately representing the physical characteristics of shale gas reservoirs. As a result, this innovative tool offers the capability to rapidly explore vast areas with high potential for shale gas reserves, enabling the identification of valuable targets efficiently. The combination of advanced technology, numerical modeling and geological expertise allows for the expedited discovery of significant resources in the field of shale gas exploration.Shale gas, an unconventional natural gas resource abundant in organic matter, has gained significant attention in global natural gas exploration as a crucial supplement and alternative to conventional natural gas sources. Due to higher electrical resistivity of oil traps in conductive sedimentary backgrounds, shale gas reservoirs are ideal targets for geophysical studies to be explored, whereby the Z-axis tipper electromagnetic method (ZTEM) can be employed to simulate and model their geoelectrical responses. The study conducted involved the utilization of an airborne method, a tool that relies on natural source transmitter, to simulate shale gas reservoirs. Initially, geoelectrical models of shallow shale gas reservoirs were constructed for three different simple geological scenarios, followed by the generation of responses through an airborne geophysical survey. The assumed electrical resistivity models were effectively reconstructed by applying an inversion algorithm to the data. This process proved to be successful in accurately representing the physical characteristics of shale gas reservoirs. As a result, this innovative tool offers the capability to rapidly explore vast areas with high potential for shale gas reserves, enabling the identification of valuable targets efficiently. The combination of advanced technology, numerical modeling and geological expertise allows for the expedited discovery of significant resources in the field of shale gas exploration.http://www.irpga-journal.ir/article_213406_a0b1a0a4470c451cc26f97d55f9e5325.pdfانجمن ژئومکانیک نفت ایراننشریه ژئومکانیک و ژئوانرژی2538-46517420250120Experimental Investigation of the Joint Geometry Effects on the Mechanical Behavior and Confined Compressive Strength of Jointed Rock MassesExperimental Investigation of the Joint Geometry Effects on the Mechanical Behavior and Confined Compressive Strength of Jointed Rock Masses384621340510.22107/jpg.2025.472880.1239FAهادیمختاریانگروه مهندسی معدن، دانشکده مهندسی، دانشگاه کاشان، کاشان، ایرانمجیدنوریان بیدگلیگروه مهندسی معدن، دانشکده مهندسی، دانشگاه کاشان، کاشان، ایرانحسنمومیوندگروه مهندسی معدن، دانشکده فنی مهندسی، دانشگاه ارومیه، ارومیه، ایران0000-0002-6106-9779Journal Article20240813This article investigates the role of joint geometrical characteristics, including orientation, filler thickness, and roughness type, on the confined compressive strength of jointed rock masses. A series of comprehensive laboratory experiments was designed and conducted to achieve this. In the first stage, limestone rock samples were used according to the experimental design. Using a cutting machine, two samples were prepared with wavy and ribbed artificial roughnesses at different angles of 0, 30, 45, and 60 degrees. Gypsum and cement filler materials with specific resistances in thicknesses of 3, 5, and 8 mm were utilized to examine the effect of filler material thickness. After triaxial laboratory tests were performed with a hook cell device at two confining pressure levels (5 and 14 MPa), the following key results were obtained: (a) higher confining pressures (14 MPa) significantly enhance compressive strength, with ribbed joints showing a more pronounced response than wavy joints, (b) for both roughness types, compressive strength was lowest at a 30-degree angle, highest at a 0-degree angle, and intermediate at a 60-degree angle, confirming the effect of anisotropy, and (c) thicker fillers generally improved strength at lower pressures but were less effective at higher pressures. These findings emphasize the importance of considering pressure conditions, joint orientation, and filler thickness in optimizing the mechanical behavior of jointed rock masses.This article investigates the role of joint geometrical characteristics, including orientation, filler thickness, and roughness type, on the confined compressive strength of jointed rock masses. A series of comprehensive laboratory experiments was designed and conducted to achieve this. In the first stage, limestone rock samples were used according to the experimental design. Using a cutting machine, two samples were prepared with wavy and ribbed artificial roughnesses at different angles of 0, 30, 45, and 60 degrees. Gypsum and cement filler materials with specific resistances in thicknesses of 3, 5, and 8 mm were utilized to examine the effect of filler material thickness. After triaxial laboratory tests were performed with a hook cell device at two confining pressure levels (5 and 14 MPa), the following key results were obtained: (a) higher confining pressures (14 MPa) significantly enhance compressive strength, with ribbed joints showing a more pronounced response than wavy joints, (b) for both roughness types, compressive strength was lowest at a 30-degree angle, highest at a 0-degree angle, and intermediate at a 60-degree angle, confirming the effect of anisotropy, and (c) thicker fillers generally improved strength at lower pressures but were less effective at higher pressures. These findings emphasize the importance of considering pressure conditions, joint orientation, and filler thickness in optimizing the mechanical behavior of jointed rock masses.http://www.irpga-journal.ir/article_213405_91633d6b4a6209c8c7e066faa2f652ef.pdfانجمن ژئومکانیک نفت ایراننشریه ژئومکانیک و ژئوانرژی2538-46517420250120Analysis of the stability of open-hole multilateral wells with consideration of intermediate principal stressAnalysis of the stability of open-hole multilateral wells with consideration of intermediate principal stress476121340810.22107/jpg.2025.488426.1244FAحسنقاسم زادهدانشگاه صنعتی خواجه نصیرالدین طوسی0000-0001-6267-9619عرفانرحیمیدانشگاه صنعتی خواجه نصیرالدین طوسیمحمد علیایرانمنشدانشگاه صنعتی خواجه نصیرالدین طوسی0000-0003-4036-0935Journal Article20241112Geomechanics is one of the sciences that plays a fundamental role in the production of energy from the earth. Today, this science is widely used in the design and drilling of wells, as well as in reservoir engineering. Safe drilling is an essential parameter in the oil and gas industry. Modern drilling methods, such as multilateral(ML) wells, increase production efficiency. However, drilling such wells is associated with mechanical instability. Those issues depend on the formation strength parameters, in-situ stress, well-direction, pore-pressure, and fluid parameters. The study of stability requires a failure criterion. Hereof, some failure criteria do not consider the role of intermediate principal stress(σ2), which is proven to have a considerable effect on mechanical failure. Our study uses the three-dimensional(3D) finite element method(FEM) to investigate the stability and solid deformation of an ML well that follows the Mohr-Coulomb(MC) and Mogi-Coulomb(Mogi-C) failure criterion to studying of mechanical failure. The results were shown in different graphs such as changes in surface pressure, flow lines around the well and fracture for different borehole pressures using Mogi-C and MC fracture criteria. Our results revealed that the weakest range in these wells is at the junction of branches. Due to the principal stress effects, using the Mogi-C criterion is more safe and closer to reality. The results demonstrate an approximate 30% reduction in predicted failure points under pressures exceeding 30 MPa when employing the Mogi-C criterion, with predicted failures decreasing from approximately 15% to 5% at 35 MPa.Geomechanics is one of the sciences that plays a fundamental role in the production of energy from the earth. Today, this science is widely used in the design and drilling of wells, as well as in reservoir engineering. Safe drilling is an essential parameter in the oil and gas industry. Modern drilling methods, such as multilateral(ML) wells, increase production efficiency. However, drilling such wells is associated with mechanical instability. Those issues depend on the formation strength parameters, in-situ stress, well-direction, pore-pressure, and fluid parameters. The study of stability requires a failure criterion. Hereof, some failure criteria do not consider the role of intermediate principal stress(σ2), which is proven to have a considerable effect on mechanical failure. Our study uses the three-dimensional(3D) finite element method(FEM) to investigate the stability and solid deformation of an ML well that follows the Mohr-Coulomb(MC) and Mogi-Coulomb(Mogi-C) failure criterion to studying of mechanical failure. The results were shown in different graphs such as changes in surface pressure, flow lines around the well and fracture for different borehole pressures using Mogi-C and MC fracture criteria. Our results revealed that the weakest range in these wells is at the junction of branches. Due to the principal stress effects, using the Mogi-C criterion is more safe and closer to reality. The results demonstrate an approximate 30% reduction in predicted failure points under pressures exceeding 30 MPa when employing the Mogi-C criterion, with predicted failures decreasing from approximately 15% to 5% at 35 MPa.http://www.irpga-journal.ir/article_213408_0ca7d0226cf3ae30b3f8144f09a226af.pdfانجمن ژئومکانیک نفت ایراننشریه ژئومکانیک و ژئوانرژی2538-46517420250120Developing New Empirical Relations among Strength and Elastic Properties of Carbonate Rocks with Their Petrophysical Properties Using Particle Swarm Optimization Algorithm and Regression Analysis: A Gas Reservoir from Southern of IranDeveloping New Empirical Relations among Strength and Elastic Properties of Carbonate Rocks with Their Petrophysical Properties Using Particle Swarm Optimization Algorithm and Regression Analysis: A Gas Reservoir from Southern of Iran628321797410.22107/jpg.2025.462735.1235FAامینعسگریدانشجوی دکتری مکانیک سنگ/ دانشگاه صنعتی شاهرودمحمدمهراددانشکده مهندسی معدن، نفت و ژئوفیزیک دانشگاه صنعتی شاهرود0000-0002-3623-2474ایماندختمصطفویشرکت نفت و گاز پارسمیشاپزشکیشرکت نفت و گاز پارسJournal Article20240613The static Young’s modulus (Esta) and the uniaxial compressive strength (UCS) are key parameters in the geomechanical study of hydrocarbon reservoirs. These parameters are typically estimated using empirical models that relate the strength and elastic parameters of the rock to their petrophysical properties. In the present research, the existing empirical models in the literature (specifically for carbonate rocks) were compiled and investigated, this was followed by performing experimental tests on 27 core samples to measure the porosity (n), the density (ρ), the compressive and shear wave velocities (Vp and Vs, respectively), Esta and UCS for a carbonate gas reservoir in the south of Iran. Next, particle swarm optimization (PSO) and regression analysis (RA) were conducted to develop estimator models for the Esta and UCS. Results of this study showed that the best models produced by the PSO algorithm were more accurate than not only the best models produced by the RA, but also the models proposed by previous researchers by 7% and 48%, respectively, for the Esta and by 10% and 7%, respectively, for the UCS. On this basis, it was strongly recommended to apply the empirical correlations developed through the PSO for more accurate estimation of the studied parameters across the investigated field and similar fields.The static Young’s modulus (Esta) and the uniaxial compressive strength (UCS) are key parameters in the geomechanical study of hydrocarbon reservoirs. These parameters are typically estimated using empirical models that relate the strength and elastic parameters of the rock to their petrophysical properties. In the present research, the existing empirical models in the literature (specifically for carbonate rocks) were compiled and investigated, this was followed by performing experimental tests on 27 core samples to measure the porosity (n), the density (ρ), the compressive and shear wave velocities (Vp and Vs, respectively), Esta and UCS for a carbonate gas reservoir in the south of Iran. Next, particle swarm optimization (PSO) and regression analysis (RA) were conducted to develop estimator models for the Esta and UCS. Results of this study showed that the best models produced by the PSO algorithm were more accurate than not only the best models produced by the RA, but also the models proposed by previous researchers by 7% and 48%, respectively, for the Esta and by 10% and 7%, respectively, for the UCS. On this basis, it was strongly recommended to apply the empirical correlations developed through the PSO for more accurate estimation of the studied parameters across the investigated field and similar fields.http://www.irpga-journal.ir/article_217974_c61063869dba29aa86d7b8839e6c4576.pdf