International Journal of Oil, Gas and Coal Technology (36 papers in press)

Regular Issues

• Application of signal envelope classification to estimate shear slowness from conventional cement bonding logging tools  
  by Hamid Heydari Gholanlo, Majid Nikkhah 
  Abstract: The shear wave velocity is crucial for characterising geomechanical reservoirs and analysing wellbore stability in oil and gas wells drilled into the crust. In many cases, the use of dipole sonic logging tools, which are equipped with the latest acoustic measuring technology and can provide shear slowness, is avoided. Conventional acoustic tools that offer compressional wave slowness are not adequately developed for geomechanical reservoir modelling. This paper proposes a novel method for generating a shear slowness profile along the depth using conventional cement bonding tools. To achieve this, an algorithm based on signal envelope classification has been developed. A well in southwestern Iran was selected to evaluate the proposed model’s performance. The comparison between the dipole sonic shear slowness and the shear slowness obtained from cement bonding tools indicates that the proposed model is highly accurate in measuring shear wave slowness in well-cemented intervals. [Received: April 5, 2024; Accepted: October 23, 2024]
  Keywords: monopole logging tools; shear wave slowness; dipole logging tools; signal processing; wave envelope.
  
  
• Study on deformation and seepage characteristics of water-filled coal rocks under different mining methods  
  by Jiabo Geng, Xiang Lan, Gaoxiong Zeng, Kui Zhao, Xiaoshuang Li, Shibin Tang 
  Abstract: Understanding the mechanical evolution of coal rock and the permeability of gas and water is crucial for deep coalbed methane (CBM) mining. Based on three classical mining methods protective coal-seam mining (PCM), top-coal caving mining (TCM), and non-pillar mining (NM), the gas-driven and water-driven methods are designed and carried out in a permeability test study on water-saturated coal rock. The results are as follows: 1) the gas-driven can promote the seepage of water in the water-saturated coal rock more than the water-driven test, and generates more dissipated energy; 2) the effective stress-strain curves of the specimens changed from the initial proposed linearity to hysteresis, and dissipated energy during hysteresis increases with increasing stress level; 3) the relative permeability of gas under two-phase seepage conditions in water-saturated coal rock (Krg) in the TCM occupies a greater dominance by the stress and fluid repulsion, which indicates that the mining methods have less influence on the relative permeability of water under two-phase seepage conditions in water-saturated coal rock (Krw) than on Krg. [Received: 23 May 2024; Accepted: 23 October 2024]
  Keywords: mining method; water-saturated coal rock; driving seepage; relative permeability.
  
  
• Public perception of natural gas and climate change  
  by Emrah Akyuz 
  Abstract: Climate change is considered one of the most significant environmental problems of the so-called anthropocene epoch. The main cause of climate change is the excessive consumption of fossil fuels. Relatively little is currently known about public perception of the relationship between natural gas and climate change. To address this gap, face-to-face semi-structured interviews were conducted with natural gas users in Turkey to determine the public perception of the relationship between natural gas and climate change. Three main conclusions were reached in this study: first, natural gas users perceive that natural gas contributes positively to climate mitigation; second, natural gas users perceive that natural gas is an environmentally friendly energy source; and third, there is an inverse correlation between the level of knowledge and public acceptance of natural gas in climate change mitigation. This research concludes that natural gas is perceived as a socially acceptable energy source in climate change mitigation. [Received: May 11, 2024; Accepted: September 18, 2024]
  Keywords: energy policy; fossil fuels; natural gas; climate change; public perception.
  DOI: 10.1504/IJOGCT.2025.10070766
   
  
• Study on the thermal control properties of inorganic hydrate salts doped coal mine polyurethane sealant  
  by Wangrui Yang, Chaoyu Hao 
  Abstract: The polyurethane (PU) material commonly used in underground air leakage plugging operations in coal mines is prone to problems such as heat accumulation, thermal release, and toxic gas release due to its large heat release in the curing process, poor thermal stability and insufficient stability. To address these problems, this study introduces inorganic hydrate salts to modify the material, aiming to enhance its thermal stability and safety. By conducting temperature measurement experiments with single hydrate salt doping of PU, two inorganic hydrate salts with good cooling effects were identified: MgSO4?7H2O and Na2CO3?10H2O. Subsequently, by conducting temperature measurement experiments with orthogonal doping of different mass fractions of MgSO4?7H2O and Na2CO3?10H2O into the PU system, and simulating the calculation of indicator parameters such as the glass transition temperature, mean square displacement, and diffusion coefficient for each doping system, the best modification formula was identified as the addition of 16wt% MgSO4?7H2O and 12wt% Na2CO3?10H2O to PU white material. The results show that inorganic hydrate salts can significantly improve the thermal control performance of PU materials at this doping ratio, thereby enabling its widespread application in environments such as underground coal mines. [Received; September 24 2024; Accepted: November 26 2024]
  Keywords: polyurethane sealant; curing temperature; molecular dynamics; MD; thermophysical properties; orthogonal design.
  
  
• The role of stirring type in the formation of uniform structures of ZSM-5 - gamma alumina enriched with Si  
  by Dino Dewantara, Ambo Intang, Djoni Bustan, Sri Haryati 
  Abstract: The synergistic enhancement of ZSM-5 zeolite and gamma alumina in catalysis is of great interest to the chemical industry. This study aims to overcome the individual drawbacks of these materials by using a combination of physical agitation techniques with variations of mechanical and sonochemical agitation. The morphological characterisation process includes scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), SEM elemental mapping, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The study demonstrated that ZSM-5 was successfully formed with distinctive characteristics, as evidenced by SEM and FTIR analysis, which revealed the formation of core groups of ZSM-5. The sonochemical stirring effect yielded superior outcomes, as the stirring down to the micromolecular level facilitated effective agitation. The combination of ZSM-5 and ?-Al2O3 resulted in a uniform morphology, with the Si/Al ratio exhibiting a higher Si composition due to the addition of silica. The crystal planes of ZSM-5 and ?-Al2O3 were identified through XRD, indicating that ZSM-5 was successfully combined with ?-Al2O3 to form a uniform structure. [Submitted: August 19, 2024; Revised: October 25, 2024]
  Keywords: ZSM-5; ?-Al2O3; material combined; physical-mechanical; physical sonochem.
  
  
• Risk assessment of ammonium salt crystallisation in wax oil hydrogenation cooling exchange equipment  
  by Haozhe Jin, Xinyu Liu, Xiaofei Liu, Chao Wang, Dexiao Fu 
  Abstract: Aiming at the tube bundle of wax oil hydrogenation air cooler in a petrochemical enterprise, the crystallisation law and flow deposition distribution of ammonium salt in multi-fluid environment are comprehensively studied by combining process analysis with numerical simulation prediction. Based on the process modelling of the hydrogenation heat exchange system and the multiphase flow distribution of the easily crystallised components, the fugacity coefficient method is used to fit and correct the ammonium salt crystallisation equilibrium curve. The multiphase flow model and discrete phase model are used to predict and analyse the deposition position and deposition amount of ammonium chloride crystallisation. The results show that the crystallisation temperature of ammonium chloride in the system is 206 C, and there is a crystallisation risk of ammonium chloride in the air cooler. The non-uniform flow field leads to the distribution difference of multiphase flow. As the flow progresses, the fluid of each phase in the pipeline begins to stratify and is stable after a certain distance, and the water phase is enriched at the bottom of the pipeline. The particle retention rate of ammonium chloride particles near the inlet pipe is larger, reaching 10.07%. [Received: June 30 2023; Accepted: June 24 2024]
  Keywords: wax oil hydrotreater; heat exchange equipment; crystallisation of NH4Cl; multiphase flow; risk assessment.
  
  
• Intensified transesterification of algae oil using ultrasonic cavitation  
  by Dhundiraj P. Deshpande, Utkarsh Maheshwari, Vivek Rangarajan, Amruta Adwant, Shrikant Nanwatkar 
  Abstract: In the todays time of energy crunch, sustainable method employed for mitigating greenhouse gas emissions and improving energy security can be obtained utilising algal oil for production of biodiesel. The present work focuses on utilisation of ultrasonic cavitation i.e. high sound wave frequency as an enhancing technique as a sustainable solution for enhancing the transesterification of algal oil. The parameters [reaction temperature (30-50 C), catalyst concentration (0.5-1 wt%), reaction duration (30-60 minutes), and methanol-to-oil molar ratio (6:1-10:1)] are optimised to boost the quality and yield of biodiesel. The optimised conditions for the process are utilising 1% of NaOH catalyst, 9:1 methanol to oil molar ratio, 45 min. reaction at 40 C providing 96.3% methyl esters. Produced biodiesel is following ASTM D-975, providing viscosity, flash point, density, indicating exceptional fuel quality thus restoring the belief of benefits of utilising ultra-sonication for biodiesel production considering all the environmental constraints. [Received: June 17, 2024; Accepted: November 27, 2024]
  Keywords: biodiesel; ultra sonication; renewable energy; algal biomass; methyl ester yield.
  DOI: 10.1504/IJOGCT.2025.10071870
   
  
• Fractal characteristics analysis of pore structure in tight sandstone reservoirs of the He 8 member, Shihezi formation: eastern Ordos Basin  
  by Kun Fu, Peilong Meng, Jingjian Wang, Hongyan Yu 
  Abstract: The He 8 member in the eastern Ordos Basin is an important reservoir and requires further investigation to fully characterise the pore structure of this tight sandstone reservoir. Casting thin sections and SEM analysis were utilised to qualitatively examine the varieties of pore and throat types within the He 8 member reservoir. Combined with capillary pressure curve morphology, pore-throat distribution, and structure parameters, the characteristics of pore and throat size distribution were quantitatively assessed, and the pore-throat assemblage patterns were summarised. Twelve representative samples were chosen to investigate the fractal characteristics of the reservoir’s pore structures through fractal theory. The findings suggest that there are four types of pore-throat assemblage patterns within the target reservoir. The fractal dimensions of macropores and mesopores exhibit a strong correlation with porosity, permeability, and pore structure parameters. The mineral composition and the content within the reservoir serve as inherent factors determining the fractal dimension. [Received: October 22 2024; Accepted: January 15 2025]
  Keywords: Ordos Basin; tight sandstone reservoir; high-pressure mercury injection; pore structure; fractal characteristics.
  
  
• Performance forecast for two vertical fractured wells in laterally heterogeneous gas reservoirs by boundary element method  
  by Feng Tian, Wei Gao, Jianghang Wang, Hai Zhou 
  Abstract: This paper establishes a mathematical model for two vertical fractured wells in laterally heterogeneous gas reservoirs to predict and optimise production. The model is solved successfully by using the boundary element method, and the results show excellent agreements with the numerical solutions. Subsequently, typical well test curves are developed, and the crossflow occurs between the radial flow and boundary-dominated flow. Furthermore, the influences of heterogeneity and production allocation ratio are emphatically analysed. The results demonstrate that a greater share should be assigned to the well in high permeability region; otherwise, the generation of this reverse crossflow from high permeability areas to low permeability areas will produce greater energy loss. In a two-region gas reservoir with a permeability ratio of 1:2, the optimal production allocation ratio is 2:3. Compared to the reference case, the cumulative production increases are about 12.5%. In summary, a reasonable production allocation prevents significant regional pressure differences and extends the production time to obtain a higher cumulative gas production. [Received: October 28, 2024; Accepted: December 16, 2024]
  Keywords: gas reservoirs; vertical fractured wells; heterogeneity; boundary element method; BEM; crossflow.
  
  
• Application of 1D CNN-BiGRU hybrid neural network to identify reservoir rock types in sandstone reservoir  
  by Xinhao Zhang, Xianguo Zhang, Huafeng Liu, Xiao Li, Wenyu Li 
  Abstract: Differences in reservoir petrology and physical properties of reservoir rocks significantly impact oil and gas field development. Accurate classification of reservoir rock type (RRT) and intelligent logging identification are essential for locating high-quality reservoirs, geological modelling, and studying the remaining oil distribution We introduce a method for the classification and prediction of reservoir rock types using core samples, conventional logging and deep learning methods. This method is the first to apply a hybrid structure of the one-dimensional convolutional neural network and bidirectional gated recurrent unit (1D CNN-BiGRU) to reservoir rock type identification. The hybrid model is compared with single 1D CNN, BiGRU, and random forest models. In the test dataset, this hybrid model achieved an accuracy of 82.5%, with F1 scores of 0.778, 0.779, and 0.827 for RRT1, RRT2, and RRT3, respectively. Its performance surpassed that of the other models. [Received: October 16, 2024; Accepted: February 20, 2025]
  Keywords: reservoir rock type; RRT; hierarchical clustering; deep learning; hybrid model; convolutional neural network; CNN; gated neural network.
  
  
• Development and application status of internal floating roof used for petrochemical storage tank  
  by Wei Liu 
  Abstract: Internal floating roof (IFR) could act as the core component to inhibit the evaporation of combustible vapour and decrease the fire explosion danger effectively in the petrochemical storage tank. However, some fire safety accidents about the internal floating tank still occur during the practical use. In this paper, the related fire accidents have been collected and analysed, in an attempt to investigate the potential fire hazard of IFR. Development and current situation of IFR product have been summarised and discussed here, and its fire resistant weakness also has been extracted from the common products in term of structure and materials comprehensively. And the development tendency of IFR from the internal floating tank has been discussed finally. Moreover, this paper mentions and compares the standard and regulation about the requirements on the fire resistance and fire test of IFR from China and abroad here. [Received: March 23, 2024; Accepted: October 13, 2024]
  Keywords: internal floating roof; IFR; fire resistant weakness; structure; material; standard.
  
  
• Optimising the yield of neem oil biodiesel using response surface methodology and grey wolf optimisation  
  by Ashish Chhikara, Ashwani Kumar Dhingra, Deepak Chhabra, Sunita Dhingra, Pardeep Kumar 
  Abstract: Sustainable energy sources, such as biodiesel, can help address the depletion of fossil fuels and their environmental impacts. This study optimises biodiesel yield from neem (Azadirachta indica) oil through transesterification, utilising grey wolf optimisation (GWO) and response surface methodology (RSM). Input factors such as the methanol and neem oil molar ratio, reaction temperature, reaction time, and stirrer rotational speed have been chosen to influence the yield of methyl ester (biodiesel) yield. Thirty experiments have been conducted using a matrix generated by a central composite design based on RSM to develop the prediction models. GWO outperformed RSM in prediction models, showing better root mean squared error and coefficient of determination. The biodiesel yield of 97.22% has been achieved using GWO with a methanol-oil molar ratio of 6.42, at a reaction temperature of 58.36 C, a reaction time of 85 minutes, and a stirring speed of 415 rpm. The physicochemical properties and FTIR analysis of processed neem oil biodiesel are within the acceptable range. [Received: November 27, 2024; Accepted: March 3, 2025]
  Keywords: neem oil biodiesel; response surface methodology; RSM; grey wolf optimisation; GWO; transesterification.
  
  
• Evaluation of oil price volatility development  
  by Monika Burghauserová, Josef Gulyás, Robin Kunju Mol Raj 
  Abstract: One of the major consistent challenges that have faced the energy industry is defining crude oil price forecasting with several implications for the oil and gas market. This paper examined the trend of oil price volatility from January 1990 to March 2024 using the ARIMA model and made a forecast for further development until 2030. The outcome showed a very dynamic tendency in the oil price curve, with steep fluctuations during important periods such as the financial crisis in 2008, the collapse of prices in 2014-2016, and the COVID-19 pandemic. Geopolitical conflicts, world economic cycles, and changes in supply-demand conditions became the main determinants of price volatility. The analysis projects volatility to continue in 2024-2025, with prices fluctuating in the range of $55-65 per barrel, underpinned by supply uncertainties and geopolitical tensions. A more gradual stabilisation would then take hold after 2025, with prices possibly settling at $16 to $19 a barrel through 2029-2030 and further firming up to $24 in early 2031. Such findings raise awareness among all the stakeholders within the oil and gas markets to increase their risk management and strategic activities. [Received: September 30, 2024; Accepted: March 7, 2025]
  Keywords: oil price volatility; time series analysis; ARIMA modelling; content analysis; forecasting; econometrics; energy markets.
  DOI: 10.1504/IJOGCT.2025.10071369
   
  
• Hydraulic fracturing technology of key gangue inclusion in thick coal seam and its application  
  by Yabin Gao, Guoqiang Liu, Hao Zheng, Xiaoya Guo 
  Abstract: The concept of key gangue and the corresponding hydraulic fracturing technology were proposed for thick coal seams. A hydraulic fracturing test system was developed. The confining pressure ratio plays a crucial role in crack propagation and fracture surface morphology. The results show that the presence of primary fractures in thick coal seams can effectively guide fracture propagation, while horizontal fractures significantly reduce the energy required for fracture initiation and facilitate fracture propagation within the coal seams. Furthermore, the number of gangue layers was found to have a significant impact on the stability of the coal seams, with a higher number of gangue layers leading to increased stability. The application of this technology resulted in a significant reduction in top coal fragmentation, a decrease in the pressure step of the working face, a 5% increase in the recovery of top coal, and a 20% increase in caving efficiency. [Received: September 18, 2024; Accepted: March 7, 2025]
  Keywords: thick coal seam with gangue; key gangue; hydraulic fracturing; field application.
  
  
• The simulation and experimental study of leakage noise sources in gas pipeline bends  
  by Shengjun Zhang, Rongshan Nie, Cen Chen, Yu Wu, Xiaoyu Liang 
  Abstract: Leakage acoustic source characteristics are essential for studying sound wave propagation. In natural gas pipelines, elbows alter flow velocity and pressure, affecting leak acoustic properties. This study focuses on elbow leak issues using aeroacoustic theory and CFD simulations with ANSYS Fluent, analysing leaks at 0 (straight pipe), 45, and 90 elbows through a 10 mm hole under varying pressures. A test rig was built to compare simulation and experimental results. The findings indicate that: 1 the sound pressure level (SPL) of leak noise increases with pressure; 2) under the same pressure, larger elbow angles result in higher leak sound power, with the 90 elbow producing the highest; 3) at the same pressure, SPL in the 425 Hz range decreases as: straight pipe > 90 elbow > 45 elbow. These findings support acoustic-based leak localisation methods. [Received: October 1, 2024; Accepted: February 27, 2025]
  Keywords: natural gas; pipeline; elbow; numerical simulation; acoustic source characteristics.
  DOI: 10.1504/IJOGCT.2025.10071370
   
  
• Experimental study on heat transfer in heavy oil reservoirs during in-situ combustion  
  by Jiuzhi Sun, Yunjie Shu, Yi Pan, Yanchao Wang, Juan Huang, Zhaoxuan Li 
  Abstract: Heavy oil and extra-heavy oil, characterised by their high viscosity, extraction difficulties, and low oil recovery, critically require efficient extraction methodologies. The in-situ combustion (ISC) technique offers a promising solution by injecting air into the reservoir to ignite heavy oil, using heat to improve recovery; however, its intricate mechanisms necessitate further optimisation. This study established an indoor simulation platform to investigate the effects of ignition temperature, porosity, gas injection rate, and injection duration on heat transfer. The experimental results showed that ignition temperature, porosity, and gas injection rate have significant effects on the oxidation and combustion of heavy oil. At 240 C, the combustion front struggled to propagate, while at 280 C, it stabilised with peak temperatures above 400 C. Increasing porosity promoted temperature rise, and the combustion front propagated optimally at a gas injection rate of 1,600 mL/min. However, at 1,800 mL/min, combustion became too intense, hindering front propagation. Extending the reaction time increased the propagation distance, but due to the limitation of reservoir fuel, continuous propagation was not possible. This study provided significant experimental and theoretical guidance for further exploration and optimisation of the ISC technique, contributing to the enhancement of unconventional energy extraction. [Received: 8 November 2024; Accepted: 4 April 2025]
  Keywords: heavy oil; in-situ combustion; combustion property; enhanced oil recovery; reservoir heat transfer.
  DOI: 10.1504/IJOGCT.2025.10070803
   
  
• Multi parameter fusion fracture comprehensive identification based on calibration data: a case study of shale reservoirs in southern Ordos  
  by Jiaqi Sun, Kesai Li, Di Wang, Naihui Wang, Yufei Yang, Xianhong He, Jie Wang, Zehou Xiang 
  Abstract: As a migration channel and storage space for oil and gas, fractures are the key to oil and gas exploration and development. Due to the small scale and complex development of shale reservoir fractures, it is difficult to identify and characterise them quantitatively, so it is necessary to carry out shale fracture logging and identification. In this paper, the fracture characteristics of shale reservoirs are analysed based on core, imaging and conventional logging data in the Ordos Basin. The stratigraphic data were corrected by forward simulation, and the identification criteria were established by using the intrusion difference ratio, grey correlation degree and comprehensive fracture index method, with an identification accuracy of more than 80%. When the index is greater than 0.15, the fracture development is in good agreement with the actual fracture development, which can be used for shale fracture identification and lay the foundation for shale oil and gas exploration and development. [Received: August 16, 2024; Accepted: March 7, 2025]
  Keywords: Ordos basin; shale fractures; intrusion difference ratio; grey correlation; fracture comprehensive index.
  DOI: 10.1504/IJOGCT.2025.10070823
   
  
• Quantitative characterisation of storage space and oil occurrence in low-maturity organic-rich shales: a case study of 3rd member of Chang 7 formation on the Southern Margin of Ordos Basin, China  
  by Dongling Xia, Wenchao Fang, Xuejie Qin, Jun Pu, Houjian Gong, Hong Qiu 
  Abstract: The fluid vacuum imbibition experiments were performed to quantitatively evaluate the storage space and oil occurrence in low-maturity organic-rich shales. Results showed that 1) the imbibition volume of water was significantly lower than that of oil, reflecting the important influence of organic pores on the storage space and occurrence state in shale reservoirs; 2) the average inorganic porosity is 3.0% and average organic porosity is 0.6%, the storage space of low mature shales is mainly composed of inorganic pores. In contrast to high-maturity shales, the porosity of low-maturity shales decreases with increasing TOC; 3) the average volume proportion of free-state oil is 32.5%, and the average volume proportion of dissolved-state oil is 67.5%. In contrast to high-maturity shales, low-maturity shale oil mainly exists as dissolved-state, and as TOC increases, the volume proportion of dissolved-state oil increases, which is unfavourable for oil mobility. [Received: September 12, 2024; Accepted: March 20, 2025]
  Keywords: shale oil; low-maturity; storage space; oil occurrence; organic matter.
  
  
• Deformation characteristics and structural evolution mechanism of bituminous coal under thermo-hydro-mechanical-chemical coupling  
  by Jianhang Shi, Zengchao Feng, Zhenhua Li, Guoying Wang, Dong Zhou 
  Abstract: Studying the thermal deformation characteristics of coal under thermo-hydro-mechanical-chemical coupling is crucial for analysing roof stability, surface subsidence, and heat injection channel formation during the in situ pyrolysis mining of coal. Therefore, in this study, the deformation characteristics, gas production characteristics, and pore structure evolution as well as strength of bituminous coal during carbonisation and steam pyrolysis were explored. The results show that: 1) coal sample deformation can be divided into two stages: softening and pyrolysis deformation. Softening deformation depends solely on temperature, and pyrolysis deformation is affected by the severity of coal pyrolysis; 2) The deformation of bituminous coal and the evolution of pore and crack structures influence each other. Deformation promotes changes in pore and crack structures, and these structural changes serve as the internal drivers of deformation; 3) Below 400?, steam injection accelerates the softening deformation of bituminous coal. Meanwhile, above 400?, deformation intensifies considerably under steam pyrolysis conditions owing to increased gas production of the coal sample compared to that during carbonisation. [Received: August 12, 2024; Accepted: April 9, 2025]
  Keywords: bituminous coal; carbonisation; steam pyrolysis; deformation; high temperature and high pressure.
  DOI: 10.1504/IJOGCT.2025.10071136
   
  
• Simulation and optimisation for DMR natural gas liquefaction unit  
  by Ahmed S. Fathalla, Mohammed Hefny, Monica Toderas, Mostapha Salem Mansour, Fathy Shokry 
  Abstract: Dual mixed refrigerants natural gas liquefaction technology (DMR) has been simulated to determine the optimal operational parameters in terms of flowrate ratios for the mixed refrigerants utilised to maintain main cryogenic heat exchangers’ stability and prevent temperature profile distortion as result of insufficient heat transfer throughout the main cryogenic heat exchangers that logically will occur if the cooling medium (refrigerants) flowrates will vary. This study examines specific ratios between two mixed refrigerants (MR1, MR2 vapour, MR2 liquid) and liquefied natural gas (LNG) produced, particularly during operations at varying feed gas flowrates. The study resulted in optimal operating zones, which are indicated by ratios such as LNG to MR2L (0.199 to 1.79), MR2V to MR2L (0.49), and MR1/MR2L (1.24 to 2.031) and those ratios showed resulted high production rate without compromising the integrity of the machinery or the operational procedures employing specific flow rate ratios. [Received: 17 January 2025; Accepted: 22 April 2025]
  Keywords: simulation; Aspen HYSYS; liquefied natural gas; LNG; optimisation; dual mixed refrigerant unit.
  DOI: 10.1504/IJOGCT.2025.10071556
   
  
• Multi-response optimisation of waste cooking oil transesterification for improved biodiesel yield and quality using RSM  
  by Rohit Khatri, Om Prakash Jakhar 
  Abstract: This study presents a multi-response optimisation technique for the waste cooking oil biodiesel production process. The study’s objective is to use the multi-response optimisation technique to find the optimal set of input parameters for the transesterification process for biodiesel yield and kinematic viscosity simultaneously. The experimental runs were developed using the box Behnken design (BBD) approach, and the multiple responses were analysed using response surface methodology (RSM). ANOVA was conducted to investigate the impact of parameters on the response. Chemical composition was determined by a GC-MS test, and the conversion of waste cooking oil (WCO) to esters was assessed using 1HNMR and a FTIR test. The present study reports an impressive yield of 96.6% and a kinematic viscosity of 5.4 cSt for biodiesel production. The accuracy of the data was confirmed by determining R2 values, which were found to be 97% and 94% for biodiesel yield and kinematic viscosity, respectively. [Received: September 22, 2024; Accepted: April 21, 2025]
  Keywords: biodiesel; transesterification; multi-response optimisation; ANOVA; box Behnken design; BBD; Fourier-transform infrared; FTIR; gas chromatography-mass spectrometry; GC-MS; 1HNMR.
  DOI: 10.1504/IJOGCT.2025.10071793
   
  
• Fractal characterisation of pore structure of Longmaxi Formation shale in northern Guizhou using NMR  
  by Wenju Chai, Feng Tian, Shaojie Zuo, Peng Xia 
  Abstract: This study focuses on the fractal characterisation of pore structure of the core samples from the Longmaxi Formation in northern Guizhou utilising scanning electron microscopy, mineral composition analysis and NMR. The permeability is calculated by using the improved SDR model proposed by Zhou et al., followed by an analysis of the impact of rock physical properties and mineral composition on pore structure. The results reveal that the samples exhibit a multi-fractal structure and the NMR-derived fractal dimensions are primarily distributed between 2.70 and 2.87, with an average of 2.77, indicating a higher degree of complexity compared to that observed in the Sichuan Basin. The fractal dimensions show a negative correlation with porosity, and the influence of larger pores on porosity is greater than that of smaller pores. Furthermore, a negative correlation is observed between permeability and fractal dimensions. Quartz content and calcite content are inversely related to pore structure complexity. In contrast, the presence of clay minerals contributes to increased pore complexity as their content rises. [Received: November 15, 2023; Accepted: March 10, 2025]
  Keywords: northern Guizhou; shale reservoir; pore structure; nuclear magnetic resonance; NMR; fractal dimension.
  DOI: 10.1504/IJOGCT.2025.10071890
   
  
• X-ray photoelectron spectroscopy investigation of nitrogen and sulphur functionalities during pyrolysis of Dongqu coal mine and Yachen coal mine of Shanxi province  
  by Meihua Wang, Yunkun Wang, Chao Bu, Yu Feng, Xudong Zhao, Wen Yang 
  Abstract: In this paper, samples from Dongqu coal mine and Yachen coal mine in Shanxi Province were pyrolysed at 300 to 900?. The X-ray Photoelectron Spectroscopy (XPS) was carried out to study the occurrence characteristics of nitrogen and sulphur in raw coal and semi-coke coal at different temperatures. The results showed that with the increase of pyrolysis temperature, pyrrole transforms into pyridine; quaternary nitrogen content decreases gradually; and nitrogen oxide content increases first and then decreases at high temperatures. The inorganic sulphur in coal is transformed into organic sulphur at high temperatures, and thiol (thioether) and pyrite in both coals are decomposed completely at 600?. Desulphurisation should focus on unstable and abundant inorganic sulphur. Understanding the occurrence characteristics and transformation rules of nitrogen and sulphur in coal through the results of this study is of great significance for promoting coal processing and utilisation, and reducing environmental pollution. [Received: January 14, 2024; Accepted: July 07, 2024]
  Keywords: X-ray photoelectron spectroscopy; XPS; Dongqu coal mine; Yachen coal mine; semi-coke; elements; occurrence characteristic.
  DOI: 10.1504/IJOGCT.2025.10071891
   
  
• Advancing drag coefficient correlations for non-spherical particles in power-law fluids  
  by Can Polat 
  Abstract: This study addresses the critical challenge of predicting the settling velocity of non-spherical particles in non-Newtonian fluids. Two established correlations between drag coefficient and particle Reynolds number were refined to enhance their applicability to non-spherical particles in Power-law fluids. A systematic analysis of model coefficients across varying particle sphericities revealed the necessity of quantifying the coefficients with particle shape. By incorporating sphericity and optimising model parameters using experimental data, the complex interplay between drag coefficient, particle Reynolds number, and particle shape is captured, demonstrating improved flexibility at low particle Reynolds numbers and accurate representation of upward concavity observed at high particle Reynolds numbers. These improvements are reflected as a decrease in mean relative errors over a wide range of particle Reynolds numbers and sphericities, and in the predictive capability demonstrated in model validation tests. [Received: February 15, 2025; Accepted: May 31, 2015]
  Keywords: settling velocity; drag coefficient; particle Reynolds number; power-law fluids; non-spherical particles.
  DOI: 10.1504/IJOGCT.2025.10071910
   
  
• Performance and emission analysis of a homogeneous charge compression ignition engine fuelled with compressed natural gas  
  by Naveen Kumar, Pawan Kishore Jha, R.C. Singh 
  Abstract: The present study investigates the impact of different HCCI percentages on key engine parameters such as brake thermal efficiency (BTE), volumetric efficiency, exhaust gas temperature (EGT), and gaseous emissions, including NOX, HC, and CO. A data acquisition unit (DAU) was used to control the auto-ignition timing of the HCCI mode, ensuring precise and consistent combustion at different operating conditions. The results suggest that 20% HCCI offers the best trade-off of performance and emissions, achieving high brake thermal efficiency (BTE) with minimal HC and CO emissions. Higher HCCI percentages lower BTE and volumetric efficiency due to reduced combustion temperatures and intake air displacement, while NOX emissions significantly decrease at 60%-80% HCCI, though HC and CO emissions rise beyond 40% due to incomplete combustion. CO2 emissions increase with load but decline at higher HCCI levels, whereas O2 emissions remain largely stable. HCCI technology presents a promising pathway for cleaner and more efficient engines, supporting sustainable transportation with continued refinement. [Received: 4 April 2025; Accepted: 22 May 2025]
  Keywords: compressed natural gas; CNG; emission; engine performance; ethanol; HCCI diesel engine.
  DOI: 10.1504/IJOGCT.2025.10072263
   
  
• Study on the disturbance law of natural fracture on ground stress field  
  by Zhaohui Dai, Qin Li, Siyang Qiu, Xiangyi Yi, Wenling Chen, Ying Sun 
  Abstract: The change of in-situ stress field in reservoir has a significant effect on the stability of natural fractures and the effectiveness of hydraulic fracturing. Based on the theory of fracture mechanics, a two-dimensional numerical model of reservoir rock disturbed by natural fractures is established, and the variation law and influence range of stress field around natural fractures are simulated by finite element method. The results show that: 1) the existence of natural fractures disturbs the magnitude and direction of the in-situ stress field. The range of stress disturbance increases quadratically with the increase of natural fracture length; 2) according to the compressive and tensile stress, different regions can be quantitatively divided around the natural fracture. When the natural fracture angle is 30 - 60, the stress disturbance is the most obvious; 3) the degree of stress concentration at both ends of natural fractures is positively correlated with stress difference or Youngs modulus. [Received: March 28, 2024; Accepted: June 28, 2024]
  Keywords: ground stress field; natural fracture; geo-stress balance; stress-deflection; stress disturbance range.
  DOI: 10.1504/IJOGCT.2025.10072286
   
  
• Crossing the digital Rubicon: innovation pathways and strategic choices in Chinas coal industry transformation  
  by Xue Lei, Xueguo Xu, Huijuan Qiao 
  Abstract: This study examines how digital transformation impacts total factor productivity (TFP) in Chinese coal enterprises through technological innovation. Using panel data from A-share listed coal companies (2012-2022), we find that digital transformation significantly enhances TFP by fostering innovation in decision making, production techniques, and business models. We uncover a nuanced relationship between government subsidies and innovation: moderate subsidies amplify digital transformations positive effects, while excessive subsidies may crowd out independent innovation. Managerial short-termism can impede technological advancement and diminish digitalisation benefits. Heterogeneity analysis shows digitalisations positive impacts are more pronounced in central regions and state-owned enterprises. This research contributes to the discourse on industrial policy, technological change, and sustainable development in carbon-intensive industries. It offers insights for policymakers navigating energy transition, emphasising the importance of balanced government support, long-term managerial vision, and targeted digital strategies in fostering innovation and productivity growth. [Received: February 4, 2025; Accepted: July 2, 2025]
  Keywords: digital transformation; total factor productivity; TFP; technological innovation; coal industry; energy transition.
  
  
• Optimised design and evaluation of cement slurry for HPHT well integrity in Basin X  
  by Hai T. Nguyen, Khaled A. Elraies, Tarek Al-Arbi Ganat, Tu V. Truong 
  Abstract: This study presents the development and evaluation of a high-performance cement slurry specifically engineered for the complex high-pressure, high-temperature (HPHT) conditions of Basin X, offshore Vietnam. Unlike generalised HPHT slurry formulations in prior studies, this research addresses a region-specific challenge, incorporating a customised combination of silica-based stabilisers, synthetic retarders, and manganese tetroxide weighting agents to mitigate strength retrogression and ensure long-term well integrity. The slurry demonstrated exceptional performance, achieving a mixability rating of 4/5, stable rheological behaviour across temperature ranges (plastic viscosity of 50 cP; yield point of 20 lb/100 ft2), and fluid loss under 50 ml/30 minutes. It maintained thickening times suitable for placement even at elevated temperatures and reached compressive strengths of 474.1 psi at 12 hours and 931.5 psi at 24 hours. By addressing both operational risks and geological challenges unique to Basin X, this study delivers a tailored, field-tested slurry design that advances HPHT cementing practices and supports safe, reliable well operations under extreme subsurface conditions. [Received: October 4, 2024; Accepted: July 2, 2025]
  Keywords: high-pressure; high-temperature; HPHT; slurry design; production liner; cement additives; strength retrogression; early setting.
  DOI: 10.1504/IJOGCT.2025.10072649
   
  
• Sensitivity and critical values of prediction indexes of gas outburst of composite coal seams based on energy theory  
  by Weiwei Su, Yujin Qin, Shouqing Lu 
  Abstract: The accurate prediction of gas outbursts plays a crucial role in preventing and managing these events, which can have devastating effects on the safety of miners. In order to improve the accuracy, a new model for gas expansion energy was developed based on energy theory and combined with both steady diffusion and unsteady diffusion models. The relationship between outburst energy, regional prediction indexes, and coal seam depth was discussed, it is proposed that for soft and hard composite coal seams (SHCS), the gas content, with a critical value of 9.00 m3/t, was determined as the regional prediction index. Mover, it was discovered that local prediction indexes were significantly responsive to alterations in gas pressure. Notably, the K1, with a critical value of 0.60 mL/(g min0.5), was identified as the primary local prediction index. The results of these investigations establish a robust theoretical basis for enhancing the precision of gas outburst prediction indexes. [Received for review: June 2, 2024; Accepted: March 7, 2025]
  Keywords: soft coal; composite coal seams; regional prediction index; local prediction index; outburst energy.
  DOI: 10.1504/IJOGCT.2025.10072802
   
  
• Forecasting future demand for coal, oil and gas: application with related to smart cities  
  by Ravi Kumar 
  Abstract: Forecasting future demand for coal, oil, and gas is essential for ensuring energy security, optimising resource allocation, and supporting strategic planning - particularly in the context of developing smart cities. This study explores advanced forecasting techniques to predict the consumption patterns of fossil fuels, using a data-driven framework that integrates historical consumption trends, economic indicators, and environmental policies. The objective is to enable policymakers and urban planners to make informed decisions that balance energy needs with sustainability goals. By applying machine learning algorithms and time-series models, the analysis offers insights into future energy demand under different scenarios. The results highlight the ongoing importance of coal, oil, and gas in urban infrastructures, while also emphasising the need for a gradual transition to renewable sources. This research provides a valuable tool for smart cities to plan their energy mix, reduce emissions, and align with global climate objectives through proactive energy demand forecasting. [Received: January 20, 2025; Accepted: July 23, 2025]
  Keywords: smart meter data: communication: data pre-processing: benchmark models: natural gas: smart meter dataset.
  DOI: 10.1504/IJOGCT.2025.10072952
   
  
• Design and simulation of a skid-mounted medium-pressure recovery process for scattered natural gas in marginal oil and gas fields  
  by Hanyong Li, Qiyang Sun, Peng Han, Bo Yu 
  Abstract: At present, due to economic, technological and other reasons, approximately 140 billion cubic meters of natural gas are flared off each year worldwide, resulting in resource waste and environmental pollution, and the recovery potential is huge. In this paper, a skid-mounted medium-pressure recovery process for scattered natural gas is established based on the dispersed onshore remote gas well associated gas venting scene. Aspen HYSYS software is used to simulate the filling process of storage tank and tank truck, which determines the changing law of the process parameters such as pressure and flow rate, and clarifies the influencing factors of the filling time. Through the economic evaluation, it is concluded that the investment payback period is shorter when the process treatment gas volume in 3,500~6,000 Nm³/d, and economic benefits can be obtained. The results can provide a process method with simple flow and high economy for the efficient recovery and utilisation of scattered natural gas in marginal oil and gas fields. [Received: April 22, 2024; Accepted: October 4, 2024]
  Keywords: scattered natural gas; skid-mounted; medium-pressure recovery; Aspen HYSYS; economic and environmental evaluation.
  DOI: 10.1504/IJOGCT.2025.10072869
   
  
• Leak detection in petroleum pipelines using fuzzy logic and statistical simulation methods  
  by Pham Son Tung, Vo Quoc Thong 
  Abstract: This paper proposed a novel approach that combined fuzzy logic with statistical simulation methods to continuously monitor pipelines for potential leaks. Detailed workflows and real data were given for analysis and comparison. Results indicated that integrating fuzzy logic with either Monte Carlo simulation or the bootstrap method yielded more accurate predictions than using only fuzzy logic. This approach addressed uncertainties in real-world scenarios, such as faulty measuring devices and the limited availability of data for validation. Additionally, the paper provided detailed programming to automate result extraction, eliminating the need for manual data processing and reducing response time. By requiring, continuous monitoring of pressures and flow rates at just two locations – both ends of the pipeline – this method can be easily integrated into existing control systems, enhancing leak detection while maintaining a low computational cost. [Received for review: September 30, 2023; Accepted: September 17, 2024]
  Keywords: leak detection; pipelines; fuzzy logic; Monte Carlo simulation; bootstrap method.
  DOI: 10.1504/IJOGCT.2025.10072665
   
  
• Characterisation of surface and structural properties of Permian coals from Sohagpur Coalfield, India: a comprehensive analysis  
  by Kaushal Kishor, Manish Kumar Srivastava, Alok K. Singh 
  Abstract: The amphiphilic nature of coal is crucial for determining its suitability for applications like combustion. A study was conducted on the Sohagpur coalfield in India to assess the hydrophobic and hydrophilic properties of coal samples. Three coal samples with distinct megascopic characteristics were selected for a comprehensive analysis using proximate and ultimate analyses, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infrared spectroscopy (FT-IR). The analyses revealed significant concentrations of C, O, N, Al, and Si on the coal surfaces, with XPS and FT-IR confirming the presence of both aliphatic and aromatic carbon groups. Additionally, XPS identified SiO₂ and Al₂O₃, consistent with FT-IR results. The study found a correlation between hydrophilic functional groups and increased moisture content. Overall, the Sohagpur coal samples showed more hydrophobic than hydrophilic characteristics, indicating their suitability for combustion. [Received: April 19, 2024; Accepted: October 5, 2024]
  Keywords: coal; XPS; FT-IR; structural characterisation; Sohagpur Coalfield; aliphatic; aromatic; quartz; hydrophobic; industrial utilisation; India.
  DOI: 10.1504/IJOGCT.2025.10072868
   
  
• Route selection for mine haulage road considering dynamic topographic changes and fuel consumption  
  by Qun Wang, Qintao Niu, Yu Chen 
  Abstract: The development of an open-pit mine haulage system relies on manual trial-and-error methods to determine route selection schemes, which have the problems of high subjectivity, low efficiency, and challenges in haulage cost optimisation. Based on analysing the balance between the driving force and resistance, and the power balance of mining dump truck engines, this study proposes a fuel consumption prediction model for mining electric wheel dump trucks. A fuel consumption cost grid is constructed based on the fuel consumption prediction model, and fuel consumption costs and terrain elevation differences are used as comprehensive costs. This study proposes a haulage road route selection algorithm based on minimising the comprehensive costs and ensuring route smoothness, thereby optimising route selection outcomes. This approach offers valuable guidance for designing efficient haulage systems in open-pit mine development. [Received: June 24, 2024; Accepted: September 11, 2024]
  Keywords: open-pit coal mine; fuel consumption; route selection algorithm; haulage road design.
  DOI: 10.1504/IJOGCT.2025.10072865
   
  
• Effect of adding fusel oil with gasoline on performance, combustion, and emission characteristics of gasoline injection engine  
  by Gopinath Dhamodaran, Ganapathy Sundaram Esakkimuthu, Sathyanarayanan Seetharaman, Ramesh Krishnan 
  Abstract: Fusel oil is a 5-carbon structure fuel, and it is a by-product of the alcohol manufacturing process. Fusel oil provides higher octane number and oxygen percentage compared to gasoline and this provides an opportunity to improve the performance of an engine. This study investigates the effect of adding fusel oil to gasoline on the properties of gasoline/fusel oil blends and the performance, emission, and combustion characteristics of gasoline engine. The addition of fusel oil with gasoline produced lower density, lower calorific value, and higher oxygen percentage and RON of the gasoline/fusel oil blend. The study found that for all engine speeds F30 blend produced higher brake thermal efficiency as compared to gasoline, 15.12% higher BTE is observed in the F30 blend at 2,800 rpm. At 2,800 rpm, lower hydrocarbon (48 ppm) and carbon monoxide (0.013%) is observed F30 blend, but NOx is observed with higher values. Furthermore, engine input parameters were optimised to achieve the maximum engine performance with a desirability of 0.993 and higher R2 values ranging between 0.995 and 0.998. [Received: June 2, 2023; Accepted: June 19, 2024]
  Keywords: oxygenates; octane number; gasoline; unburned hydrocarbon; carbon monoxide; fusel oil.
  DOI: 10.1504/IJOGCT.2025.10072866
   
  
• Future of WSNs and IoT technology in the oil and gas industry, through MEMS energy harvesters  
  by Musaab Zarog 
  Abstract: Oil and natural gas represent 55% of energy sources and therefore they remain the main choice for fulfilling energy needs. For more efficiency, all machinery and equipment including thousands of kilometres of transporting pipelines need to be monitored continuously and in real-time. Any delay in detecting failures or degradation can result in a huge and serious impact on the environment, humans, and property. With the advancement of the internet of things (IoT), through wireless sensor nodes (WSNs), the response to any failure can be much faster and cost-effective. Microelectromechanical (MEMS) Energy harvesters provide a solution to power hundreds of WSNs. The objectives of this paper are to analyse the current role of WSNs and IoT in oil and gas operations, and to assess the impact of MEMS-based energy harvesters on the longevity and reliability of IoT and WSN deployments. [Received: November 24, 2021; Accepted: October 25, 2024]
  Keywords: wireless networks sensors; micro-electro-mechanical systems; MEMS; energy scavenging; mechanical vibration; microsystems; ambient energy.
  DOI: 10.1504/IJOGCT.2025.10072867