Energy Extraction and Processing Science

Topic Information

Dear Colleagues,

Geological resources are one of the most abundant resources on earth, including coal, oil, and natural gas; geothermal energy; oil shale; coal bed methane; etc. These energy sources contain many non-renewable resources, and the safe extraction and rational and sustainable use of these resources are important academic topics. This project aims to publish research results of the highest quality and of lasting importance about energy, focusing on scientific issues arising in the safe production, storage, and application of geological energy sources, such as the construction of macromolecular models of different types of energy sources, the prevention and control of contaminants in the extraction process, the purification and separation of energy sources, the adsorption of auxiliary drugs on the surface of energy sources, and the rational design of energy extraction processes. The concept and sustainable development of safe extraction technologies for new energy sources, which include internal mechanisms to protect the environment from potential project damage and ensure the sustainable use of energy, will be particularly focused on. The main topics of this topic include, but are not limited to, the following:

• The monitoring and control of dust in energy extraction processes.
• Macromolecular modeling of different types of energy sources.
• CO₂ sequestration/hydrogen storage in geological formations.
• Environmental protection in resource development.
• The application of computer science to solve safety problems in energy extraction.
• the characterization of size, shape, surface area, pore structure, and strength of energy particles and agglomerates (including the sources and effects of interparticle forces).
• The adsorption of auxiliary agents at energy interfaces or surfaces.
• The adsorption process generates competitive behavior.
• Mathematical modeling and numerical simulation of coupled processes.
• The creation, storage, and transport of unconventional energy sources.
• The prevention of and reduction in geological hazards in mines.
• The mathematical aspects of rock mechanics and rock engineering.
• The production and storage of geological energy.

Dr. Yueliang Liu
Dr. Shaoqi Kong
Dr. Chuang Wen
Topic Editors

Keywords

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.0	6.2	2008	17.5 Days	CHF 2600	Submit
Environments environments	3.5	5.7	2014	25.7 Days	CHF 1800	Submit
Molecules molecules	4.2	7.4	1996	15.1 Days	CHF 2700	Submit
Polymers polymers	4.7	8.0	2009	14.5 Days	CHF 2700	Submit
Processes processes	2.8	5.1	2013	14.4 Days	CHF 2400	Submit
Sustainability sustainability	3.3	6.8	2009	20 Days	CHF 2400	Submit

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Published Papers (18 papers)

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14 pages, 8918 KiB  

Open AccessArticle

Molecular Energy of Metamorphic Coal and Methane Adsorption Based on Gaussian Simulation

by Tao Yang, Jingyan Hu, Tao Li, Heng Min and Shuchao Zhang

Processes 2024, 12(12), 2621; https://doi.org/10.3390/pr12122621 - 21 Nov 2024

Viewed by 232

Abstract

Effectively controlling the adsorption and desorption of coal and mine gas is crucial to preventing harm to the environment. Therefore, this paper investigated the adsorption of coal and methane molecules from the perspective of microscopic energy through Gaussian simulation. Gaussian 09W and GaussView [...] Read more.

Effectively controlling the adsorption and desorption of coal and mine gas is crucial to preventing harm to the environment. Therefore, this paper investigated the adsorption of coal and methane molecules from the perspective of microscopic energy through Gaussian simulation. Gaussian 09W and GaussView 5.0 software were used to construct and optimize the molecular model of four different metamorphic coals, namely lignite, sub-bituminous coal, bituminous coal, and anthracite, and their adsorption structure with methane as well as the energy, bond length, vibration frequency, infrared spectrum, and other data on the optimal structure were obtained. The binding energy of coal molecules and methane from large to small was as follows: sub-bituminous coal (7.3696 KJ/mol), lignite (6.6149 KJ/mol), bituminous coal (5.2170 KJ/mol), and anthracite (4.9510 KJ/mol). The equilibrium distance was negatively correlated with the binding energy, and the molecular structure and position of coal largely determined the binding energy. Additionally, adsorption was more likely to occur between methane molecules and hydroxyl groups. Many new vibration modes were observed during the adsorption of coal and methane molecules. This paper is of practical significance, as studying the adsorption of coal and mine gas can prevent and control mine gas outbursts and ensure safe production. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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17 pages, 6298 KiB  

Open AccessArticle

Sealing Characteristics Analysis of New Subsea Wellhead Sealing Device

by Jing Li, Bo Ning, Dezhi Qiu, Fenlan Ou, Lantao Geng, Peng Xu and Beibei Kou

Processes 2024, 12(10), 2124; https://doi.org/10.3390/pr12102124 - 29 Sep 2024

Viewed by 573

Abstract

Subsea wellhead systems are the crucial equipment for the development of oil and gas resources offshore, while the sealing device plays a vital role as the main component of the wellhead system. Once the seal fails, it is necessary to retrieve the original [...] Read more.

Subsea wellhead systems are the crucial equipment for the development of oil and gas resources offshore, while the sealing device plays a vital role as the main component of the wellhead system. Once the seal fails, it is necessary to retrieve the original wellhead system and either repair the sealing device or reinstall a new one. This will result in a delay in normal production and an increase in development costs. Therefore, a novel subsea wellhead sealing device is designed. A finite element analysis model is developed to study the underwater wellhead sealing mechanism regarding the equivalent stress and contact stress. The research results show that as the driving block gradually increases from 4 mm to 12 mm, the stress of the 12 convex parts on the sealing body also increases. The maximum equivalent stress reaches 3.5 times the yield limit, indicating that it has entered the yield stage and can achieve a more effective seal. The analysis of the contact stress of the sealing body reveals that the contact stress of the driving block increases, leading to plastic deformation of the sealing body while driving it to achieve a complete seal. In general, the finite element simulation results are consistent with the engineering practice. By analyzing the sealing characteristics, it can serve as the foundation for designing and providing theoretical support for the optimization of the metal-sealing structure. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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15 pages, 6476 KiB  

Open AccessArticle

Efficient Flotation Separation of Ilmenite and Olivine in a Weak Alkaline Pulp Using a Ternary Combination Collector Centered around Al³⁺

by Jinhui Li, Hao He, Yanhai Shao, Chenjie Liu, Rui Li, Hongqin Chen and Xiao Meng

Molecules 2024, 29(18), 4379; https://doi.org/10.3390/molecules29184379 - 14 Sep 2024

Viewed by 726

Abstract

Due to the similar physical and chemical properties of ilmenite and olivine, separating them is challenging. The flotation process, with the use of collectors, is an effective method. In this study, a ternary collector consisting of aluminum ion (III), benzohydroxamic acid (BHA), and [...] Read more.

Due to the similar physical and chemical properties of ilmenite and olivine, separating them is challenging. The flotation process, with the use of collectors, is an effective method. In this study, a ternary collector consisting of aluminum ion (III), benzohydroxamic acid (BHA), and sodium oleate (NaOL) was prepared for the flotation separation of ilmenite and olivine. Through micro-flotation experiments, molecular dynamics simulation (MD), density functional theory (DFT), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis, the synergistic effect between the components of the ternary collector and the adsorption configuration on the surface of ilmenite was investigated. The results revealed that at pH = 8, Al (III), BHA, and NaOL could coordinate and adsorb effectively on the surface of ilmenite, enhancing its floatability for separation from olivine. The adsorption configuration differed from previous reports, showing a co-adsorption of multiple forms on the surface of ilmenite. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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16 pages, 6251 KiB  

Open AccessArticle

Understanding Perforation Detonation Failure Mechanisms Based on Physicochemical Detection and Simulation Modeling

by Chaofeng Chen, Xihe Liu, Dong Ruan, Xueru Chen, Xiangtong Yang, Kun Ning and Zhilong Lian

Processes 2024, 12(9), 1971; https://doi.org/10.3390/pr12091971 - 13 Sep 2024

Viewed by 573

Abstract

With advancements in the exploration and development of deep and ultra-deep oil and gas resources, the number of ultra-deep wells continues to rise globally. This trend places higher demands on testing technology. The combined perforating and testing technique, an established method for deep [...] Read more.

With advancements in the exploration and development of deep and ultra-deep oil and gas resources, the number of ultra-deep wells continues to rise globally. This trend places higher demands on testing technology. The combined perforating and testing technique, an established method for deep and ultra-deep wells, faces challenges. Frequent test operation failures due to perforation detonation failure increase down-hole complexity, restricting the timeliness of testing operations. Current methods use mechanical calibration software to calculate the minimum safety factor of the tubing string for safety assessments. However, without a thorough understanding of perforation detonation failure theory, existing mechanical analysis software remains unreliable for assessing well safety during operations. Simply using the safety factor method lacks reliability and cannot explain the causes of perforation detonation failure. This paper examines an ultra-deep well, referred to as TW1, to analyze perforation detonation failure mechanisms. Through metal microstructure examinations, chemical composition analysis, electron microscope scanning, and numerical simulation, the study yields the following insights: (1) The packer mandrel of Well TW1 fractured due to overstress from the detonation waves. (2) Detonation wave propagation patterns along the tubing string during perforation become apparent. (3) Simulation methods reconstruct the perforation detonation process, calculating effective stress at different tubing string positions over time. (4) It introduces an innovative approach for assessing perforation detonation failure mechanisms through a combination of laboratory testing and simulation modeling. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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22 pages, 11883 KiB  

Open AccessArticle

Experimental Study on the Suspending Mechanism of Suspending Agent in Coal-Based Solid Waste Slurry for Long-Distance Pipeline Transportation

by Tao Li, Tao Yang, Heng Min, Min Cao and Jingyan Hu

Processes 2024, 12(9), 1937; https://doi.org/10.3390/pr12091937 - 9 Sep 2024

Viewed by 625

Abstract

The transportation of coal-based solid waste filling slurry (CSWFS) through pipelines for underground goaf injection is essential for enhancing mine safety and promoting green, low-carbon coal mining. To address the issue of pipeline blockage caused by the suspension sensitivity of CSWFS during long-distance [...] Read more.

The transportation of coal-based solid waste filling slurry (CSWFS) through pipelines for underground goaf injection is essential for enhancing mine safety and promoting green, low-carbon coal mining. To address the issue of pipeline blockage caused by the suspension sensitivity of CSWFS during long-distance transportation, this study proposes the addition of the suspending agent hydroxypropyl methyl cellulose (HPMC) to transform the filling slurry into a stable suspending slurry. The mechanism by which the suspending agent modifies the rheological property of CSWFS was elucidated and verified. Firstly, an evaluation index system for the suspending state of CSWFS based on the “experimental test and theoretical calculation” was established. The values for layering degree, bleeding rate time-loss, and the corresponding average time-loss rate over 0 to 120 min of A1–A5 CSWFS were recorded as 24 mm–2 mm, 3.0–0.2%, 252.4–54.2%, and 149.6–14.6%, respectively. The concentration gradient evaluation result, C/C_A = 0.91 (≥0.8), confirmed that the suspending agent maintained a stable suspending state over time for CSWFS. Secondly, it was demonstrated that the suspending agent HPMC modified the rheological property of A1–A5 CSWFS by increasing its plastic viscosity, which strengthened the viscous resistance to particle settling, thereby transforming a semi-stable slurry into a stable one. Additionally, the formation of a spatial suspending network by the suspending agent ensures that no pipeline blockage accidents occured in practical engineering applications. Furthermore, the XRD and SEM tests were utilized to verify the microstructure of the top (T) and bottom (B) samples in A4 block. It was concluded that the type of hydration products, occurrence forms, lapping compactness, and microstructural development were consistent, ultimately forming a high-strength, dense, hardened filling block. Finally, numerical simulation confirmed that the addition of suspending agent in A4 slurry formed a comprehensive spatial suspending network and a well-structured, unified system. This is one effective approach which could contribute to addressing the technical issue of pipeline blockage during long-distance pipeline transportation. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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16 pages, 2916 KiB  

Open AccessArticle

Study on the Influence of Industrial Coke Oven Size on the Quality of Metallurgical Coke

by Liangyuan Hao, Jianliang Zhang, Huan Cheng, Luying Xiao, Fei Liao and Wenjia Hu

Processes 2024, 12(8), 1637; https://doi.org/10.3390/pr12081637 - 3 Aug 2024

Viewed by 1102

Abstract

The large-scale coke oven is a developing trend in coking technology, and the influence of the industrial coke oven size on the quality of metallurgical coke needs to be revealed. Under the same raw coals and blending ratios, metallurgical cokes were obtained from [...] Read more.

The large-scale coke oven is a developing trend in coking technology, and the influence of the industrial coke oven size on the quality of metallurgical coke needs to be revealed. Under the same raw coals and blending ratios, metallurgical cokes were obtained from top-loading coke ovens with carbonization chamber heights of 6 and 7 m, respectively. The macroscopic quality and microstructure of the refined metallurgical cokes were comprehensively tested. The results showed that the conventional cold and thermal strength indexes of Coke-7m were better than those of Coke-6m. The comprehensive thermal strength at multiple temperatures further showed that the thermal strength advantage of Coke-7m was mainly manifested at low temperatures (1050 and 1100 °C) or a high temperature (1300 °C), where the solution-loss reaction mode of coke tended to be the “uniform reaction model” or “unreacted core model”. At medium temperatures, the solution-loss reaction mode tended to be the “gradient reaction model”, which had a greater destructive effect on the thermal strength of coke. At this time, the thermal strengths of the two cokes were close. Microstructure characterization revealed that industrial coke oven size mainly affected the carbon structure of coke but had little effect on pore structure. The advantage of Coke-7m regarding carbon structure is an important reason for its superior macroscopic quality compared to Coke-6m. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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18 pages, 7965 KiB  

Open AccessArticle

Effect of Flexible Tank Wall on Seismic Response of Horizontal Storage Tank

by Lifu Cui, Lijie Zhu, Yuan Lyu, Jiangang Sun and Yujian Wu

Processes 2024, 12(8), 1633; https://doi.org/10.3390/pr12081633 - 3 Aug 2024

Cited by 1 | Viewed by 951

Abstract

Horizontal storage tanks are integral to the petrochemical industry but pose significant risks during earthquakes, potentially causing severe secondary disasters. Current seismic designs predominantly assume rigid tank walls, which can lead to an underestimation of seismic responses. This study introduces a novel analysis [...] Read more.

Horizontal storage tanks are integral to the petrochemical industry but pose significant risks during earthquakes, potentially causing severe secondary disasters. Current seismic designs predominantly assume rigid tank walls, which can lead to an underestimation of seismic responses. This study introduces a novel analysis method for assessing the dynamic response of flexible-walled horizontal storage tanks. By separating the liquid velocity potential into convective and impulsive components and integrating these with beam vibration theory, we developed a simplified mechanical model. A parameter analysis and dynamic response research were conducted using numerical methods. Results indicate that flexible tank walls amplify seismic responses, including liquid dynamic pressure peaks, base shear, and overturning bending moments, compared to rigid walls. Additionally, the impact of flexible walls is more pronounced in tanks with larger radii, aspect ratios, diameter–thickness ratios, and H/R ratios. These findings highlight the necessity for revised seismic design approaches that consider wall flexibility to enhance the safety and resilience of horizontal storage tanks. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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13 pages, 7750 KiB  

Open AccessArticle

Mechanical Damage to Coal and Increased Coal Permeability Caused by Water-Based Ultrasonic Cavitation

by Xiaoyang Guo, Yijia Liu, Yanfeng Li, Cunbao Deng, Lemei Zhang and Yu Zhang

Energies 2024, 17(15), 3626; https://doi.org/10.3390/en17153626 - 24 Jul 2024

Viewed by 628

Abstract

Coalbed methane (CBM), recognized as a sustainable and environmentally friendly energy source, plays a crucial role in mitigating global climate change and advancing low-carbon energy solutions. However, the prevalence of low-permeability coal seams poses a significant challenge to effective CBM extraction. Improving coal [...] Read more.

Coalbed methane (CBM), recognized as a sustainable and environmentally friendly energy source, plays a crucial role in mitigating global climate change and advancing low-carbon energy solutions. However, the prevalence of low-permeability coal seams poses a significant challenge to effective CBM extraction. Improving coal permeability has emerged as a viable strategy to address the issue of low-permeability coal. Conventional CBM stimulation methods fall short in overcoming this obstacle. In contrast, the enhanced technique of CBM extraction by water-based ultrasonic cavitation holds great promise due to its use of high energy intensity, safety, and efficiency. Nevertheless, the inadequate theoretical framework for managing this technology impedes its widespread adoption for large-scale applications. This study investigated the impact of water-based ultrasonic cavitation treatment on coal’s properties and permeability through mechanical testing and permeability measurements conducted before and after treatment. This study also explored the process by which this technology, known as WUC-ECBM, improves coal’s mechanical properties and permeability. The findings suggest a potential stimulation technique (WUC-ECBM) for use in CBM extraction, and its physical mechanism. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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19 pages, 11144 KiB  

Open AccessArticle

Preparation and Mechanism of Shale Inhibitor TIL-NH₂ for Shale Gas Horizontal Wells

by Yuexin Tian, Xiangjun Liu, Yintao Liu, Haifeng Dong, Guodong Zhang, Biao Su and Jinjun Huang

Molecules 2024, 29(14), 3403; https://doi.org/10.3390/molecules29143403 - 19 Jul 2024

Viewed by 879

Abstract

In this study, a new polyionic polymer inhibitor, TIL-NH₂, was developed to address the instability of shale gas horizontal wells caused by water-based drilling fluids. The structural characteristics and inhibition effects of TIL-NH₂ on mud shale were comprehensively analyzed using [...] Read more.

In this study, a new polyionic polymer inhibitor, TIL-NH₂, was developed to address the instability of shale gas horizontal wells caused by water-based drilling fluids. The structural characteristics and inhibition effects of TIL-NH₂ on mud shale were comprehensively analyzed using infrared spectroscopy, NMR spectroscopy, contact angle measurements, particle size distribution, zeta potential, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The results demonstrated that TIL-NH₂ significantly enhances the thermal stability of shale, with a decomposition temperature exceeding 300 °C, indicating excellent high-temperature resistance. At a concentration of 0.9%, TIL-NH₂ increased the median particle size of shale powder from 5.2871 μm to over 320 μm, effectively inhibiting hydration expansion and dispersion. The zeta potential measurements showed a reduction in the absolute value of illite’s zeta potential from −38.2 mV to 22.1 mV at 0.6% concentration, highlighting a significant decrease in surface charge density. Infrared spectroscopy and X-ray diffraction confirmed the formation of a close adsorption layer between TIL-NH₂ and the illite surface through electrostatic and hydrogen bonding, which reduced the weakly bound water content to 0.0951% and maintained layer spacing of 1.032 nm and 1.354 nm in dry and wet states, respectively. Thermogravimetric analysis indicated a marked reduction in heat loss, particularly in the strongly bound water content. Scanning electron microscopy revealed that shale powder treated with TIL-NH₂ exhibited an irregular bulk shape with strong inter-particle bonding and low hydration degree. These findings suggest that TIL-NH₂ effectively inhibits hydration swelling and dispersion of shale through the synergistic effects of cationic imidazole rings and primary amine groups, offering excellent temperature and salt resistance. This provides a technical foundation for the low-cost and efficient extraction of shale gas in horizontal wells. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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18 pages, 2889 KiB  

Open AccessArticle

Economic Optimization of Thermal Insulation Thickness for Insulated and Electrically Traced Pipelines in Drilling Applications

by Meng Xu, Meng Gao, Ruitong Yang, Keping Wang and Zhe Yuan

Processes 2024, 12(7), 1506; https://doi.org/10.3390/pr12071506 - 17 Jul 2024

Viewed by 908

Abstract

This study presents an economic optimization model for determining the optimal insulation thickness for both thermal insulation and electric tracing pipelines. Using Life-Cycle Cost (LCC) analysis, optimization research was conducted under various working conditions to identify the most cost-effective insulation thickness. Factors such [...] Read more.

This study presents an economic optimization model for determining the optimal insulation thickness for both thermal insulation and electric tracing pipelines. Using Life-Cycle Cost (LCC) analysis, optimization research was conducted under various working conditions to identify the most cost-effective insulation thickness. Factors such as pipe diameter, operational duration, drilling fluid temperature, and heat cost were analyzed to assess their impact on the economic thickness of the insulation layer, specifically within the unique environment of drilling sites. The results provide the economic thickness and total cost for both insulated and electrically traced pipelines under different scenarios. For instance, for a DN100 pipe with rock wool insulation operating for 3600 h, the economic thickness of the electrically traced pipe insulation was determined to be 5.18 cm greater per unit length compared to the non-electrically traced pipe, resulting in an additional cost of 19.36 CNY/m. These findings offer valuable insights for optimizing pipeline insulation in drilling applications. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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39 pages, 7169 KiB  

Open AccessReview

Review of the Interfacial Structure and Properties of Surfactants in Petroleum Production and Geological Storage Systems from a Molecular Scale Perspective

by Jihui Jia, Shu Yang, Jingwei Li, Yunfeng Liang, Rongjuan Li, Takeshi Tsuji, Ben Niu and Bo Peng

Molecules 2024, 29(13), 3230; https://doi.org/10.3390/molecules29133230 - 8 Jul 2024

Cited by 1 | Viewed by 1952

Abstract

Surfactants play a crucial role in tertiary oil recovery by reducing the interfacial tension between immiscible phases, altering surface wettability, and improving foam film stability. Oil reservoirs have high temperatures and high pressures, making it difficult and hazardous to conduct lab experiments. In [...] Read more.

Surfactants play a crucial role in tertiary oil recovery by reducing the interfacial tension between immiscible phases, altering surface wettability, and improving foam film stability. Oil reservoirs have high temperatures and high pressures, making it difficult and hazardous to conduct lab experiments. In this context, molecular dynamics (MD) simulation is a valuable tool for complementing experiments. It can effectively study the microscopic behaviors (such as diffusion, adsorption, and aggregation) of the surfactant molecules in the pore fluids and predict the thermodynamics and kinetics of these systems with a high degree of accuracy. MD simulation also overcomes the limitations of traditional experiments, which often lack the necessary temporal–spatial resolution. Comparing simulated results with experimental data can provide a comprehensive explanation from a microscopic standpoint. This article reviews the state-of-the-art MD simulations of surfactant adsorption and resulting interfacial properties at gas/oil–water interfaces. Initially, the article discusses interfacial properties and methods for evaluating surfactant-formed monolayers, considering variations in interfacial concentration, molecular structure of the surfactants, and synergistic effect of surfactant mixtures. Then, it covers methods for characterizing microstructure at various interfaces and the evolution process of the monolayers’ packing state as a function of interfacial concentration and the surfactants’ molecular structure. Next, it examines the interactions between surfactants and the aqueous phase, focusing on headgroup solvation and counterion condensation. Finally, it analyzes the influence of hydrophobic phase molecular composition on interactions between surfactants and the hydrophobic phase. This review deepened our understanding of the micro-level mechanisms of oil displacement by surfactants and is beneficial for screening and designing surfactants for oil field applications. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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17 pages, 6437 KiB  

Open AccessArticle

Research on the Interaction Mechanisms between ScCO₂ and Low-Rank/High-Rank Coal with the ReaxFF-MD Force Field

by Kui Dong, Shaoqi Kong, Zhiyu Niu and Bingyi Jia

Molecules 2024, 29(13), 3014; https://doi.org/10.3390/molecules29133014 - 25 Jun 2024

Viewed by 1151

Abstract

CO₂ geological sequestration in coal seams can be carried out to achieve the dual objectives of CO₂ emission reduction and enhanced coalbed methane production, making it a highly promising carbon capture and storage technology. However, the injection of CO₂ into [...] Read more.

CO₂ geological sequestration in coal seams can be carried out to achieve the dual objectives of CO₂ emission reduction and enhanced coalbed methane production, making it a highly promising carbon capture and storage technology. However, the injection of CO₂ into coal reservoirs in the form of supercritical fluid (ScCO₂) leads to complex physicochemical reactions with the coal seam, altering the properties of the coal reservoir and impacting the effectiveness of CO₂ sequestration and methane production enhancement. In this paper, theoretical calculations based on ReaxFF-MD were conducted to study the interaction mechanism between ScCO₂ and the macromolecular structures of both low-rank and high-rank coal, to address the limitations of experimental methods. The reaction of ScCO₂ with low-rank coal and high-rank coal exhibited significant differences. At the swelling stage, the low-rank coal experienced a decrease in aromatic structure and aliphatic structure, and high-rank coal showed an increase in aromatic structure and a decrease in aliphatic structure, while the swelling phenomenon was more pronounced in high-rank coal. At the dissolution stage, low-rank coal was initially decomposed into two secondary molecular fragments, and then these recombined to form a new molecular structure; the aromatic structure increased and the aliphatic structure decreased. In contrast, high-rank coal showed the occurrence of stretches–breakage–movement–reconnection, a reduction in aromatic structure, and an increase in aliphatic structure. The primary reasons for these variations lie in the distinct molecular structure compositions and the properties of ScCO₂, leading to different reaction pathways of the functional group and aromatic structure. The reaction pathways of functional groups and aromatic structures in coal can be summarized as follows: the breakage of the O–H bond in hydroxyl groups, the breakage of the C–OH bond in carboxyl groups, the transformation of aliphatic structures into smaller hydrocarbon compounds or the formation of long-chain alkenes, and various pathways involving the breakage, rearrangement, and recombination of aromatic structures. In low-rank coal, there is a higher abundance of oxygen-containing functional groups and aliphatic structures. The breakage of O–H and C–OH chemical bonds results in the formation of free radical ions, while some aliphatic structures detach to produce hydrocarbons. Additionally, some of these aliphatic structures combine with carbonyl groups and free radical ions to generate new aromatic structures. Conversely, in high-rank coal, a lower content of oxygen-containing functional groups and aliphatic structures, along with stronger intramolecular forces, results in fewer chemical bond breakages and makes it less conducive to the formation of new aromatic structures. These results elucidate the specific deformations of different chemical groups, offering a molecular-level understanding of the interaction between CO₂ and coal. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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16 pages, 3817 KiB  

Open AccessArticle

Molecular Dynamics Simulation of the Rejuvenation Performance of Waste Cooking Oil with High Acid Value on Aged Asphalt

by Zhiyu Wang, Qiang Pei, Kunjie Li, Zhonghui Wang, Xiaodong Huo, Yongwei Wang, Xudong Zhang and Shaoqi Kong

Molecules 2024, 29(12), 2830; https://doi.org/10.3390/molecules29122830 - 14 Jun 2024

Viewed by 718

Abstract

Waste cooking oil’s (WCO’s) potential as a rejuvenator of aged asphalt has received attention in recent years, with the acid value of WCO affecting its rejuvenation effect. This study explored the rejuvenation effect of WCO with a high acid value on aged asphalt [...] Read more.

Waste cooking oil’s (WCO’s) potential as a rejuvenator of aged asphalt has received attention in recent years, with the acid value of WCO affecting its rejuvenation effect. This study explored the rejuvenation effect of WCO with a high acid value on aged asphalt by using molecular dynamics simulation. First, the representative molecules of WCO with a high acid value and asphalt were determined. The rejuvenation effect of WCO on aged asphalt was analyzed by adding different contents of WCO to an aged asphalt model. The effect of WCO on the thermodynamic properties of the aged asphalt was analyzed. The results show that WCO can restore the thermodynamic properties of aged asphalt binder to a certain extent. Regarding the microstructure of rejuvenated asphalt, WCO molecules dispersed around asphaltenes weakened the latter’s aggregation and improved the colloidal structure of the aged asphalt. In terms of interface adhesion properties, WCO can improve the adhesion properties between asphalt binder and SiO₂, but it has limited influence on water sensitivity. The results allowed us to comprehensively evaluate the rejuvenation effect of WCO with a high acid value on aged asphalt and to explore its rejuvenation mechanism. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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14 pages, 5256 KiB  

Open AccessArticle

Assessment of Combustion Cavern Geometry in Underground Coal Gasification Process with the Use of Borehole Ground-Penetrating Radar

by Zenon Pilecki, Robert Hildebrandt, Krzysztof Krawiec, Elżbieta Pilecka, Zbigniew Lubosik and Tomasz Łątka

Energies 2023, 16(18), 6734; https://doi.org/10.3390/en16186734 - 21 Sep 2023

Cited by 1 | Viewed by 1060

Abstract

In this study, the shape and size of a combustion cavity with a fracture zone in the gasified coal seam was determined with the use of control boreholes and a ground-penetrating radar (BGPR) test. The underground coal gasification (UCG) field-scale experiment was performed [...] Read more.

In this study, the shape and size of a combustion cavity with a fracture zone in the gasified coal seam was determined with the use of control boreholes and a ground-penetrating radar (BGPR) test. The underground coal gasification (UCG) field-scale experiment was performed in Carboniferous strata in coal seam 501 at a depth of approx. 460 m in the Wieczorek hard coal mine in the Upper Silesian Coal Basin, Poland. After the termination of the UCG reactor, five coring boreholes were drilled to identify the geometry of the resulting combustion cavity and the impact of the UCG process on the surrounding rock mass. Borehole ground-penetrating radar measurements were performed using a 100 MHz antenna in three boreholes with a length of about 40–50 m. This enabled the identification of the boundaries of the combustion cavity and the fracture zone in the coal seam. The fracture zones of rock layers and lithological borders near the control borehole were also depicted. As a result, the cavity was estimated to have a length of around 32 m, a width of around 7 m and a height of around 5 m. The analyses performed with the control boreholes and the BGPR provided sufficient information to determine the geometry of the combustion cavity and the fracture zone. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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5 pages, 193 KiB  

Open AccessEditorial

Energy Extraction and Processing Science

by Shaoqi Kong, Gan Feng, Yueliang Liu and Chuang Wen

Energies 2023, 16(14), 5372; https://doi.org/10.3390/en16145372 - 14 Jul 2023

Viewed by 1491

Abstract

With an increasingly tight supply of world energy resources, unconventional oil and gas resources, including shale oil and gas, coal-bed gas, tight sandstone oil and gas, have attracted much attention [...] Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

14 pages, 5324 KiB  

Open AccessArticle

Research on the Mechanism of Low-Temperature Oxidation of Asphaltene

by Zhengchong Zhao, Haiyang Yang, Jingjing He, Fuqiang Hu, Fan Cheng, Hai Liu, Chunli Gong and Sheng Wen

Molecules 2023, 28(14), 5362; https://doi.org/10.3390/molecules28145362 - 12 Jul 2023

Cited by 1 | Viewed by 1203

Abstract

Asphaltene extracted from heavy oil was oxidized by a mixture of propionic anhydride and hydrogen peroxide at a low temperature of 50 °C. Elemental analysis, infrared analysis, proton nuclear magnetic resonance analysis, and gas chromatograph/mass spectrometer analysis results indicated that oxygen addition, side [...] Read more.

Asphaltene extracted from heavy oil was oxidized by a mixture of propionic anhydride and hydrogen peroxide at a low temperature of 50 °C. Elemental analysis, infrared analysis, proton nuclear magnetic resonance analysis, and gas chromatograph/mass spectrometer analysis results indicated that oxygen addition, side chain cleavage, and condensation reactions mainly occurred in the oxidation process. The oxidation products were divided into 28% methanol solubles and 72% methanol insolubles. There were mainly fatty acids and fatty acid esters in the methanol solubles. There were also small amounts of aromatic compounds with low condensation in the methanol solubles, and the alkyl side chains were mostly short ones. The degree of aromatic ring condensation in the methanol insolubles was slightly higher than that of the pristine asphaltene. There were still some long unbroken chains in the methanol insolubles after the low-temperature reaction. The molecular dynamics simulation results show that the distribution of propionic anhydride around the asphaltene molecules can promote the oxidation of asphaltene. This low-temperature oxidation technology can be used to process asphaltenes to improve the profitability of heavy-oil-processing enterprises. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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17 pages, 7003 KiB  

Open AccessFeature PaperArticle

The Molecular Model of Organic Matter in Coal-Measure Shale: Structure Construction and Evaluation Based on Experimental Characterization

by Kunjie Li, Hongwu Tian, Yanxia Liang, Wei Guo, Yuqiong Zhao, Yanjun Meng and Shaoqi Kong

Molecules 2023, 28(13), 5203; https://doi.org/10.3390/molecules28135203 - 4 Jul 2023

Cited by 1 | Viewed by 1367

Abstract

To investigate the molecular structure and micropore structure of organic matters in coal-measure shale, the black shale samples of the Shanxi formation were collected from Xishan Coalfield, Taiyuan, and a hybrid experimental–simulation method was used for realistic macromolecular models of organic matter (OM). [...] Read more.

To investigate the molecular structure and micropore structure of organic matters in coal-measure shale, the black shale samples of the Shanxi formation were collected from Xishan Coalfield, Taiyuan, and a hybrid experimental–simulation method was used for realistic macromolecular models of organic matter (OM). Four experimental techniques were used to determine the structural information of OM, including elemental analysis, state ¹³C nuclear magnetic resonance (¹³CNMR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). With structural parameters, two-dimensional (2D) average molecular models of OM were established as C₁₇₇H₁₆₀O₈N₂S with a molar weight of 2474, which agreed well with the experimental ¹³C-NMR spectra. A realistic three-dimensional (3D) OM macromolecular model was also reconstructed, containing 20 2D molecules with a density of 1.41 g/cm³. To determine the connectivity and spatial disposition of the OM pores, focused ion beam microscope (FIB-SEM) and transmission electron micrographs (TEM) were utilized. The 3D OM pores models were developed. The results show that whether the OM pores varied from 20 to 350 nm as obtained from FIB-SEM images or less than 10 nm as observed in the TEM images, both were of poor connectivity. However, the ultra-micro pores from the 3D OM macromolecular model varied from 3Å to 10 Å and showed certain connectivity, which may be the main channel of diffusion. Furthermore, with the pressure increased, the methane adsorption capacity of the 3D OM model increased with a maximum value of 103 cm³/g at 7 MPa, indicating that OM pores less than 1 nm have a huge methane adsorption capacity. Therefore, our work provides an analysis method that is a powerful and superior tool in further research on gas migration. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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21 pages, 11485 KiB  

Open AccessArticle

Molecular Mechanism Study on the Effect of Microstructural Differences of Octylphenol Polyoxyethylene Ether (OPEO) Surfactants on the Wettability of Anthracite

by Jiajun Li, Guochao Yan, Shaoqi Kong, Xuyang Bai, Gang Li and Jiawei Zhang

Molecules 2023, 28(12), 4748; https://doi.org/10.3390/molecules28124748 - 13 Jun 2023

Cited by 3 | Viewed by 1387

Abstract

Inhalable coal dust poses a serious threat to coal mining safety, air quality, and the health of miners. Therefore, the development of efficient dust suppressants is crucial for addressing this issue. This study evaluated the ability of three high-surface-active OPEO-type nonionic surfactants (OP4, [...] Read more.

Inhalable coal dust poses a serious threat to coal mining safety, air quality, and the health of miners. Therefore, the development of efficient dust suppressants is crucial for addressing this issue. This study evaluated the ability of three high-surface-active OPEO-type nonionic surfactants (OP4, OP9, and OP13) to improve the wetting properties of anthracite via extensive experiments and a molecular simulation and determined the micro-mechanism of different wetting properties. The surface tension results show that OP4 has the lowest surface tension (27.182 mN/m). Contact angle tests and wetting kinetics models suggest that OP4 exhibits the strongest wetting improvement ability on raw coal with the smallest contact angle (20.1°) and the fastest wetting rate. In addition, FTIR and XPS experimental results also reveal that OP4-treated coal surfaces introduce the most hydrophilic elements and groups. UV spectroscopy testing shows that OP4 has the highest adsorption capacity on the coal surface, reaching 133.45 mg/g. The surfactant is adsorbed on the surface and pores of anthracite, while the strong adsorption ability of OP4 results in the least amount of N₂ adsorption (8.408 cm³/g) but the largest specific surface area (1.673 m²/g). In addition, the filling behavior and aggregation behavior of surfactants on the anthracite coal surface were observed using SEM. The MD simulation results indicate that OPEO reagents with overly long hydrophilic chains would produce spatial effects on the coal surface. Under the influence of the π-π interaction between the hydrophobic benzene ring and the coal surface, OPEO reagents with fewer ethylene oxide quantities are more prone to adsorb onto the coal surface. Therefore, after the adsorption of OP4, both the polarity and the water molecule adhesion ability of the coal surface are greatly enhanced, which helps to suppress dust production. These results provide important references and a foundation for future designs of efficient compound dust suppressant systems. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

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