International Journal of Oil, Gas and Coal Technology (40 papers in press)

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  Phase behaviour analysis of condensate gas reservoirs in Dabei oil and gas area: impact of variable wax content on dew point pressure, flash separation, and condensate recovery ( Free Full-text Access )

  by Rujun Wang, Yongliang Tang, Chengze Zhang, Dong Chen, Cong Wei, Wei Zhou, Furong Wang 
  Abstract: In the Dabei oil and gas field, addressing wax deposition in condensate gas reservoirs is crucial. By analysing field-obtained samples with varied wax contents (7%, 12%, 19%, 28%) using the HPVT-150 PVT instrument, we observed minimal changes in flash steam composition but notable enrichment in flash oil components and increased condensate oil densities. Higher wax content led to an increased flash gas-to-oil ratio, dew point pressure, and reverse condensate saturation, impacting heavy hydrocarbons. Recovery efficiency of condensate oil decreases with higher wax content and abandonment pressure at 10MPa. These findings are pivotal for developing high-wax condensate reservoirs. [Received: July 24, 2024; Accepted: March 3, 2025]
  Keywords: condensate gas reservoir; wax content; dew point pressure; phase behaviour.
  DOI: 10.1504/IJOGCT.2025.10070776
   
  
• Development of a data-driven screening model for miscible carbon dioxide flooding  
  by Palang Moronke Guful, Cavit Atalar 
  Abstract: Carbon dioxide enhanced oil recovery methods (CO2-EOR) offer both enhanced oil recovery and carbon sequestration benefits, however their profitability depends on reservoir properties and CO2 injection design which necessitates a robust screening tool to evaluate its feasibility. This study presents a novel data-driven screening tool to automate the screening process for miscible CO2 flooding. A compositional numerical simulator (CMG GEM) was used to develop a database modelling heavy, black and volatile oils to understand the impact of oil gravity on miscibility. Artificial neural networks (ANNs) were trained using this database to predict EOR performance under various conditions. Our approach addresses the limitations of traditional EOR screening criteria, which often rely on oversimplification and expert judgement. We employed a rigorous validation process, including a univariate sensitivity analysis and comparison with CMG GEM simulation results, to ensure the tool’s reliability. The ANN showed strong predictive capability, with performance indicators indicating high accuracy. This tool not only facilitates rapid and accurate CO2-EOR screening but also enhances decision making by integrating a wide range of reservoir rock and fluid characteristics. This study presents a significant advancement in the automation of EOR screening processes, providing a user-friendly and reliable solution for the oil and gas industry. [Received: 21 May 2024; Accepted: 27 July 2024]
  Keywords: screening tool; miscible CO2 flooding; neural networks; carbon sequestration; enhanced oil recovery; EOR; data-driven modelling.
  
  
• Study of rock drillability evaluation based on drilling parameters of cutting rig  
  by Xiaolei Yue, Zhongwen Yue, Yang Li, Yifei Yan, Xu Wang 
  Abstract: Accurate assessment of mechanical properties and interface information in layered rock formations is crucial for informed decision-making in geotechnical engineering. In this study, we investigated the rock drillability distribution to determine interface information in layered rock masses. Using a self-developed digital rotary drilling system, we conducted indoor experiments on layered rock masses with varying strength grades. We proposed a rock drillability index (Ld) based on the correlation between drilling specific energy and penetration rate, and analysed its variation within the rock mass. Our results demonstrate significant fluctuations in Ld across rock strata, particularly at interfaces, indicating high sensitivity to interface recognition. Additionally, we found that Ld has a positive relationship with penetration rate and a negative correlation with rock strength, reflecting both the rock's resistance to drilling damage and the interaction between the rock formation and drilling rig. In conclusion, Ld accurately identifies layered rock mass interfaces and establishes the relationship between drillability and rock strength. This study provides a theoretical framework and methodology for the application of digital drilling technology in engineering rock masses. [Received: March 20, 2023; Accepted: January 10, 2024]
  Keywords: interface identification; drillability index; layered rock mass; measurement while drilling rock.
  
  
• Modelling the impact of energy production on environmental quality of resource-rich countries  
  by Austine N. Okereke, Nancy Zigwai Yunana, Seyi Saint Akadiri, Joseph Osaro Denwin 
  Abstract: This study examines the influence of energy production on environmental degradation in resource-rich countries, utilising the pooled mean group (PMG) estimator technique spanning from 1995 to 2021. Our analysis revealed that while energy production does contribute to CO2 emissions, its impact was statistically insignificant. This suggests the potential for implementing advanced and environmentally friendly techniques in the production process. Furthermore, the study suggests that the bulk of emissions in oil-producing countries may stem from sources other than energy production, such as oil extraction itself. Our findings support the halo effect hypothesis (HEH), indicating that foreign direct investment (FDI) is associated with a reduction in CO2 emissions in the sampled region. Considering these results, policymakers should prioritise environmentally friendly policies to attract FDI inflows in countries like Nigeria. This includes encouraging investors to embrace green energy technologies and align their investments with the country’s emission reduction targets. [Received: May 18, 2023; Accepted: May 8, 2024]
  Keywords: energy production; environmental quality; foreign direct investment; FDI; time series; Nigeria; pooled mean group; PMG; halo effect hypothesis; HEH.
  
  
• A proposed method for shale permeability tensor calculation considering shale anisotropy  
  by Zengqiang Han, Shuangyuan Chen, Xiaokun Chen, Yiten Wang, Shicong Huang, Dan Xu, Chao Wang 
  Abstract: As a common structure of sedimentary rock, bedding plane causes obvious anisotropy of shale permeability. Permeability is an important parameter for evaluating shale gas reservoirs, so it is necessary to study the percolation characteristics of shale under the influence of bedding plane. In this paper, permeability tests of different bedding angles, different confining pressure, and different percolation paths (axial/radial) were carried out on the shale specimens from the northern Guizhou Depression, China. Both axial and radial permeability tests method are based on pulse decay method. According to the test result, the influence mechanism of bedding plane on shale permeability is studied. The permeability of shale specimens decreases exponentially with the increase of confining pressure and angle of bedding direction. In addition, combined with the test results and percolation theory, a permeability tensor calculation method in shale reservoir is established. The permeability model of the measuring point is established by referring to the drill hole image data in the core well, which is presented in a spherical coordinate system. The permeability varies with the bedding angle in the shale reservoir are intuitively obtained. The results can provide reference for shale gas development and well layout. [Received: November 2, 2023; Accepted: August 24, 2024]
  Keywords: anisotropic permeability; bedding plane; shale reservoir; tensor calculation method.
  
  
• Synthesis and viscosity reduction performance evaluation of oil-soluble viscosity reducer based on molecular dynamics simulation  
  by Li Hanyong, Cui Yafang, Zhong Ziye, Yu Bo 
  Abstract: The feasibility of the synthesis of oil-soluble viscosity reducer SSM was simulated by molecular dynamics simulation combined with experimental research. Then, the oil-soluble viscosity reducer SSM was synthesised by copolymerisation of three monomers of stearyl methacrylate (SMA), styrene (SM) and maleimide (MIm) by solution polymerisation. The effects of monomer ratio, reaction temperature, reaction time and initiator addition on the viscosity reduction effect of Liaohe heavy oil were investigated. Infrared characterisation results showed that SSM was successfully synthesised. Thermogravimetric analysis results show that SSM has good thermal stability and dispersibility. The results of optical microscopy and scanning electron microscopy revealed the viscosity reduction mechanism of SSM on heavy oil. [Received: May 25, 2024; Accepted: July 31, 2024]
  Keywords: molecular dynamics simulation; viscosity reduction of heavy oil; oil-soluble viscosity reducer; SSM; viscosity reduction mechanism.
  
  
• Experimental investigation on the anisotropy of rock brittleness for reservoir evaluation based on digital drilling mechanical properties  
  by Xiaoyue Yu, Mingming He, Haoteng Wang, Qin Zhao, Mingchen Ding, Jing Wang 
  Abstract: Rock brittleness is a key indicator for reservoir excavation in energy engineering, especially in oil and gas field exploitation. In this study, we developed an energy-balance model of the rock energy characteristics during rock drilling. To evaluate the anisotropic effect of rock brittleness, a drilling-based brittleness index (BI) is derived. Digital borehole tests were conducted on substrates comprising limestone, mudstone, sandstone, and shale, probing into the energy characteristics and anisotropic nature of brittleness across distinct drilling directions (0, 90, 270, and 360). A meticulous analysis was undertaken to unravel the energy traits and the progressive evolution of the BI throughout diverse drilling directions. Results suggested that the BI of limestone and sandstone exhibited an initial descent (in the drilling direction in 090) followed by an ascent (in the drilling direction in 90180), culminating at a critical direction of 90. The order of anisotropy of rock brittleness of the tested specimens was as follows: limestone (0.95) > sandstone (0.94) > mudstone (0.83) > shale (0.82). To ascertain the reliability of proposed methodology, a comparative analysis was conducted against various methods for determining the rock brittleness, revealing a predicted error margin below 5%. The digital drilling method has potential practical applications. [Received: July 18, 2024; Accepted: August 05, 2024]
  Keywords: anisotropy; brittleness; energy characteristics; drilling.
  
  
• Fast marching method for evaluation of reserves drainage volume in shale gas reservoirs considering multi-well interference  
  by Miaomiao Liu, Fenglan Zhao, Shijun Huang, Guoliang Li 
  Abstract: The fast marching method (FMM) has shown considerable potential for rapid modelling of unconventional gas reservoirs, particularly excelling in pressure front tracking efficiency. In this study, an FMM-based evaluation method is established for analysing reserves drainage volume in shale gas reservoirs under multi-well conditions. The effects of fracturing stages, stimulated reservoir volume (SRV) permeability, fracturing stage spacing, horizontal well spacing, and fracture half-length on production are investigated. By combining numerical simulation with FMM, the production of shale reservoir is analysed, and the reservoir performance is further investigated employing a three-dimensional well network development pattern. The results demonstrate that fracturing stages have the greatest impact on drainage volume, followed by fracturing stage spacing. Fracture half-length, horizontal well spacing, and SRV permeability have the least impact on drainage volume. The three-dimensional well network development pattern can reduce interference between horizontal wells at the same layer, increasing cumulative gas production by over 20%. [Received: July 10, 2024; Accepted: August 19, 2024]
  Keywords: shale gas reservoir; reserves evaluation; fast marching methods; FMM; tridimensional well pattern.
  
  
• 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: 24 June 2024; Accepted: 11 September 2024]
  Keywords: open-pit coal mine; fuel consumption; route selection algorithm; haulage road design.
  
  
• Optimising mud management: adaptive moment estimation-based ANN for predicting rheological and filtration properties of KCl-PHPA-Polyol drilling fluids  
  by Raunak Gupta, Uttam K. Bhui 
  Abstract: Field results highlight the importance of real-time monitoring of drilling-fluid properties to prevent operational issues by detecting changes in fluid rheology and filtration behaviour. Traditional laboratory methods, while precise, are time-consuming, error-prone, and do not reflect the rapidly changing conditions encountered during drilling. Thus, there is a pressing need for real-time predictive models that can adapt to on-site data for immediate adjustments. This study introduces a novel method using a deep neural network to predict the rheological and filtration properties of KCl-PHPA-polyol mud, focusing on historically underemphasised parameters like pH, alongside density and Marsh funnel viscosity (MFV). Utilising 2,000 field data points, the artificial neural network (ANN) model demonstrated robust performance, achieving R2 values between 0.738 and 0.910, and MAPE from 4.54% to 9.87%. This model significantly advances traditional methods by enhancing the interpretability and utility of ANN, improving operational efficiency through accurate prediction of key rheological and filtration attributes. [Received: June 27, 2024; Accepted: July 31, 2024]
  Keywords: adaptive moment estimation; artificial neural network; ANN; artificial neural network; rheological and filtration; KCL-PHPA-Polyol; drilling fluids.
  
  
• Experimental study and application of rock electrical properties under high temperature and high pressure based on Archie's formula: a case study of Jimsar shale oil reservoir in Xinjiang, China  
  by Xing Zhang, Jiajia Feng, Chun Yin, Meng Feng, Li You, Songsong Huang, Jian Li 
  Abstract: This study conducted rock electrical experiments under high temperature and high-pressure conditions, combined with high-pressure mercury injection and nuclear magnetic resonance experiments to analyse the response characteristics of rock electrical parameters in shale oil reservoirs. The saturation index n is positively correlated with increasing porosity and oil saturation, exponentially correlated with permeability logarithm, and negatively correlated with displacement pressure, according to experimental data. The formation factor decreases with porosity, permeability, average capillary radius, and pore throat homogeneity coefficient. Based on saturation index, formation factors, storage and seepage characteristics, and pore-throat structure, permeability and effective porosity were introduced, and two saturation correction models for high temperature and high-pressure rock electrical parameters were created. The models general applicability shows that it calculates saturation more accurately than Archies formula, with only 5% average difference from oil saturation. This study provides a more accurate and effective method for shale oil reservoir saturation interpretation. [Received: March 30, 2024; Accepted: August 16, 2024]
  Keywords: shale pore throat structure; rock electricity experiment; Archie’s equation; saturation correction model; HPMI; NMR; China.
  
  
• 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: 2 June 2023; Accepted: 19 June 2024]
  Keywords: oxygenates; octane number; gasoline; unburned hydrocarbon; carbon monoxide; fusel oil.
  
  
• A comprehensive review on biodiesel performance: advantages, challenges, policies and prospects  
  by V.N.S.R. Ratnakara Rao Guduru, Subbarama Kousik Suraparaju, Sendhil Kumar Natarajan, Ravi Kiran Sastry Gadepalli, V. Ramachandra Raju 
  Abstract: The depletion of traditional fossil fuels, escalating emissions and stringent environmental regulations in alignment with the sustainable development goals (SDGs) have catalysed significant advancements in biofuel technologies. Among these, biodiesel has emerged as a promising eco-friendly alternative to conventional diesel for use in compression ignition (CI) engines. This review elucidates the potential of biodiesel to substantially reduce emissions while maintaining engine performance comparable to that of pure diesel, thereby presenting a compelling and sustainable fuel option. Nevertheless, challenges such as increased nitrogen oxide (NOx) emissions and higher brake-specific fuel consumption necessitate innovative strategies in both production and application. This comprehensive review explores the optimisation of various biodiesel formulations, including blends with eco-friendly additives, addressing the inherent challenges and identifying opportunities to meet SDGs. This review serves as a valuable guide for researchers and developers, offering insights into selecting and refining diesel alternatives that balance performance with emissions reduction, ultimately supporting the achievement of SDGs and the transition to a greener world. [Received: 4 January 2024; Accepted: 1 July 2024]
  Keywords: biodiesel; engine performance; emissions; diesel engine; policies.
  
  
• 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, 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.
  
  
• Dynamic response characteristics of multi-gas in coal seam during gas injection process  
  by Gaowei Yue, Yanwen Zhang, Zihao Li, Minmin Li 
  Abstract: A one-dimensional gas-solid two-phase model for gas injection displacement was established, and the dynamic time-varying characteristics of gas injection displacement of multi-gas with different mixed gases were numerically analysed. The research results indicate that the permeability of coal seam N2 slowly decreases linearly with pressure, while the permeability of CO2 sharply decreases linearly with pressure. The numerical simulation results of the multi-gas adsorption/desorption flow model for coalbed gas injection are consistent with the measured results. Injecting a mixed gas with a high proportion of CO2 will increase the penetration time, but increase the initial recovery rate; Injecting a mixed gas with a large proportion of N2 will result in a lower initial recovery rate, but it will break through earlier and produce a large amount of nitrogen in the extracted gas in a short period of time. [Received: December 18, 2023; Accepted: April 20, 2024]
  Keywords: gas injection replacement; multi gas; recovery rate; dynamic response; time-varying characteristics.
  
  
• 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.
  
  
• 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.
  
  
• 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.
  
  
• 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.
  
  
• 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 04, 2024]
  Keywords: scattered natural gas; skid-mounted; medium-pressure recovery; Aspen HYSYS; economic and environmental evaluation.
  
  
• 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.
  
  
• 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.
  
  
• 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
   
  
• Seepage-induced sedimentary structures and their significance in beach bars of the Zhoushan Archipelago, China  
  by Qiheng Guo, Junlin Chen, Dirk Knaust, Shuting Shi, Xiangli Shi, Zhenkui Jin, Chenglin Liu 
  Abstract: Sedimentary structures induced by water seepage are described from modern beach bars within the Zhoushan Archipelago in China, including two unique types, herein referred to as: 1) seepage tubes; 2) seepage beads. Their formation is related to water seepage in sandy sediments, where the seepage tubes are formed by the downward seepage of pore water in sandy sediment, while the seepage beads are formed by the vertical superposition of multiple beaded horizontal seepage layers. The results show that unique terrain and rapid water ingress and retreat related to tides control the formation of these sedimentary structures. The seepage-induced sedimentary structures can be divided into vertical vadose belts that develop seepage tubes, horizontal undercurrent belts with seepage beads, and water-table variation belts with both seepage tubes and seepage beads appearing alternately. These sedimentary structures are hitherto undescribed and contribute to an improved understanding of similar sedimentary structures in the geological record. [Received: April 3, 2024; Accepted: July 7, 2024]
  Keywords: sedimentary structures; water seepage; seepage tubes and beads; beach bar; Zhoushan Archipelago; China.
  DOI: 10.1504/IJOGCT.2025.10070517
   
  
• Experimental investigation for partially premixed compression ignition in a diesel engine using n-butanol, biodiesel and diethyl ether blends  
  by Gangeya Srinivasu Goteti, P. Tamilselvan 
  Abstract: This research aims to optimise combustion by reducing emissions and improving performance parameters. This research also investigates biodiesel usage and an ignition improver with an increased compression ratio of 20 by supplying n-butanol with preheated air. The experimental work was first conducted with diesel to generate baseline data. It was then performed using a blend of n-butanol, diesel, and an ignition improver. The experiment was repeated by using the combustible mixture B25N15DE1, which contains Prosopis juliflora methyl ester, diesel, DEE, and n-butanol vapours on a volume basis. The n-butanol mists were added by port injection in the proportion of 15% into the preheated air stream to attain partially premixed compression ignition. The increased brake thermal efficiency (33.21%) and reduced emissions of hydrocarbons with 65 ppm and carbon monoxide of 0.29% were observed, along with the increased heat release rate (48.1 J/°CA) at a partially premixed mode. [Received: 14 June 2022; Accepted: 24 June 2024]
  Keywords: brake thermal efficiency; combustion; crank angle; emission; heat release rate.
  DOI: 10.1504/IJOGCT.2025.10070506
   
  
• Comparative analysis of energy consumption and carbon emission in the boil-off gas recondensation process  
  by Kun Huang, Xin Wang, Li Cao, Kun Chen, Nan Zhou, Yuxuan Gao 
  Abstract: In this study, the goal is to minimise energy and carbon emissions in liquefied natural gas (LNG) receiving stations by optimising the boil-off gas (BOG) recondensation process. Four processes were evaluated using a performance model that considered both energy and emissions. A genetic algorithm optimised the parameters for lowest possible consumption and emissions. The analysis revealed that while increasing stages of recondensation and compression, and altering cooling methods, led to a minor increase in energy consumption, it resulted in significant emission reductions. Higher BOG content further amplified these savings. Notably, a two-stage recondensation process with pre-cooling and post-cooling (case D) achieved the greatest reduction in carbon emissions, confirming its effectiveness in reaching carbon neutrality goals, despite a slight rise in energy use compared to the base process (case A). [Received: March 19, 2024; Accepted: July 4, 2024]
  Keywords: BOG recondensation; parameter optimisation; energy consumption; carbon emission; process selection.
  DOI: 10.1504/IJOGCT.2025.10070505
   
  
• Prediction and optimisation of electricity market clearing price in Turkey by using machine learning methods  
  by Murat Ince, Ahmet Kabul, Mesut Aksoy 
  Abstract: This research aims to reduce price instability in the market clearing price (MCP) in Turkey by estimating MCP using machine learning techniques based on production resource-based data. The model will balance market prices by shifting from a price-based to a resource-based approach, minimising the price of electricity units by decreasing imported energy production and increasing domestic and renewable energy production. Thus, in this study, the effect of MCP on electricity unit prices and forecast values until July 29, 2023, was compared. By using past year data between 2014 and 2022, the MCP price in 2023 is determined. As a result of artificial neural network prediction, the average MCP value for 2023 was revealed 85.9 USD. The best results were obtained with artificial neural network (ANN) (R² = 0.8827, RMSE = 0.0309 and MAE = 0.0223). Also, the model predicts estimated 2023 energy production by incorporating real-time production values from energy resource production data. The performance indicators of the implemented forecasting methods increase efficiency in future production forecasts and contribute to accurate pricing in energy purchases. [Received: February 17, 2024; Accepted: July 7, 2024]
  Keywords: market clearing price; MCP; energy efficiency; machine learning; regression; Turkey; artificial neural network; ANN.
  DOI: 10.1504/IJOGCT.2025.10070507
   
  
• A prediction of China's dependence on foreign oil up to 2060  
  by Guangyue Xu, Lanmei Zang, Shuang Li, Qiuyu Song, Kyaw Jaw Sine Marma 
  Abstract: China's dependence on foreign oil has increased rapidly in the past few decades. If it continues to grow at the current rate, it will have a series of negative impacts on energy security, economic development, and international competition. The future trajectory of China's foreign oil dependence has become the most critical subject for debate. This paper focuses on such issues from three different perspectives - the historical perspective of China's oil dependence on foreign countries, the main factors affecting China's oil dependence on foreign countries, and the prediction of oil dependence on foreign countries. The forecast shows that China's oil dependence on foreign countries will likely reach its peak before 2030, and it is expected to reach its peak as early as 2026, with a maximum value of 75.24%. The realisation of this possible peak depends on the control of oil demand and the progress of oil production technology. Therefore, it is necessary to increase innovative technology orienting the oil industry and control consumption to address with high dependence on foreign oil. [Received: October 4, 2023; Accepted: February 12, 2024]
  Keywords: China's petroleum; external dependency; prediction; energy security; peak.
  DOI: 10.1504/IJOGCT.2025.10070508
   
  
• Modern steel production using biomass energy in 21st century: blessing or curse?  
  by Avash Kumar Saha, Ramesh Kumar, Arup Kumar Mandal 
  Abstract: The global shift towards renewable energy has increased biomass utilisation, driven by climate concerns, energy security, and fossil fuel volatility. This review examines biomass's role in decarbonising steel production, a significant CO₂ emitter due to its reliance on carbon-intensive processes. Biomass, including wood pellets, ethanol, and palm oil, offers a renewable alternative to fossil fuels. Research shows that biochar can replace coke in blast furnaces, reducing emissions. However, challenges include ensuring consistent biomass quality, optimising properties, and addressing logistical and economic issues. Economic viability hinges on biomass availability, costs, energy prices, and supportive policies. Investments in biomass supply chains and retrofitting steel plants are essential. This study compiles relevant information to determine if biomass in the iron and steel sectors will be a blessing or a curse in the twenty-first century. Despite challenges, biomass holds promise for sustainable steel production, needing careful management to avoid becoming a curse. [Received: October 16, 2023; Accepted: July 25, 2024]
  Keywords: pellets; biomass; industries; sustainable development; fossil fuels.
  DOI: 10.1504/IJOGCT.2025.10070510