Article
Energy & Fuels
Dameng Liu, Yanbin Yao, Xuehao Yuan, Yanhui Yang
Summary: Field observations show that nearly 59% of CBM wells in the southern Qinshui Basin experience insufficient gas production due to the water-blocking effect caused by fracturing fluids or formation water. Experimental results indicate a stronger water-blocking effect in anthracite coal compared to bituminous coal, with water-blocking threshold pressure gradients following a positive power-law relationship with normalized water saturation. Study findings emphasize the importance of understanding gas and water interaction in coal reservoirs during gas production.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
Shasha Zhang, Caifang Wu, Xiaojie Fang, Ningning Liu, Xiuming Jiang, Jiang Han
Summary: The stress sensitivity and compressibility of the pore system in coal greatly affect coal permeability and porosity, which are crucial for coalbed methane development. Understanding water transformation under stress and during drying is important for analyzing water's impact on pore structure.
NATURAL RESOURCES RESEARCH
(2022)
Article
Engineering, Environmental
Chao Li, Yong Qin, Tao Guo, Jian Shen, Yi Yang
Summary: This study measured the high-pressure adsorption isotherms of two coal samples to investigate the methane adsorption process and mechanisms in coal. The results showed that micropore filling and surface adsorption are the primary adsorption mechanisms for supercritical methane in coal, with micropore filling occurring in pores smaller than 1.1 nm and surface adsorption occurring in 1-2 nm pores. Micropore filling adsorption plays a significant role in the overall methane adsorption, and the nano-confined effect and low water saturation contribute to the enrichment of free gas in deep coalbed methane (CBM). These findings provide insights into the occurrence behavior of unconventional natural gas in reservoirs.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Engineering, Environmental
Dameng Liu, Yanbin Yao, Yanhai Chang
Summary: Evaluation of free and adsorption gas in the in-situ reservoir is important for coalbed methane exploration and production. Current methods for estimating the adsorbed gas content have limitations due to unreasonable or questionable mathematical assumptions. This study proposes a method using NMR and excess isothermal adsorption experiments to accurately quantify free and adsorbed methane in the reservoir.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Energy & Fuels
Shuang Ju, Qiming Huang, Gang Wang, Jian Qiao, Shibin Wang, Cunli Qin
Summary: This study investigated the synergistic stabilization mechanism of SiO2 nanoparticles and SDS during foam fracturing. The results showed that an appropriate concentration of SDS can enhance the adsorption of SiO2 nanoparticles at the gas-liquid interface, thereby improving foam stability.
Article
Geosciences, Multidisciplinary
Huimin Jia, Yidong Cai, Qiujia Hu, Cong Zhang, Feng Qiu, Bin Fan, Chonghao Mao
Summary: Stress sensitivity has negative effects on the permeability and production of coalbed methane reservoirs. This study explores the degree of stress sensitivity using the curvature of the stress-sensitivity curve, dividing it into five stress stages and determining four critical stress points. The initial permeability of coal affects the number of critical stresses and the drainage strategies of CBM wells. The stress-sensitivity coefficient determines the ability to maintain stable CBM production. For fractured CBM reservoirs, a slower depressurization rate is recommended, while for reservoirs with fewer natural fractures, a faster depressurization rate is possible.
FRONTIERS OF EARTH SCIENCE
(2023)
Article
Geosciences, Multidisciplinary
Yina Yu, Zhaoping Meng, Caixia Gao, Yixin Lu, Jiangjiang Li
Summary: The permeability of deep coal reservoirs in coalbed methane extraction is affected by temperature and pore pressure. This study explores the permeability evolution during CBM production under different temperatures and establishes a coupling coal permeability function. The results show the sensitivity of coal reservoir permeability to stress and temperature, and provide guidance for reasonable drainage of CBM wells in different geothermal fields.
NATURAL RESOURCES RESEARCH
(2022)
Article
Environmental Sciences
Ming-yi Chen, Xiao-yun Chen, Liang Wang, Fu-chao Tian, Yu-meng Yang, Xue-jie Zhang, Ya-pu Yang
Summary: Coalbed methane is a new clean energy source with potential ecological damage. This study investigates the adsorption characteristics of water on coal and its impact on pore structure and methane adsorption, providing important insights for evaluating coalbed methane reserves and productivity.
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
(2022)
Article
Engineering, Environmental
Yong Li, Zhuangsen Wang, Shuheng Tang, Derek Elsworth
Summary: Differentiating between adsorbed and free methane in coal and shale is essential for gas recovery strategies and greenhouse gas control. The proposed method using nuclear magnetic resonance spectroscopy successfully determines adsorbed/free methane ratios and compares favorably with standard isothermal adsorption measurements.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Geosciences, Multidisciplinary
LingRui Kong, YongJiang Luo, JianXin Tang, YanLei Wang, Fang Yuan, Shuang Li, YongJin Hao
Summary: This study investigates the permeability damage characteristics of contaminated coal samples using a core flow test method. The results show that the permeability of contaminated coal samples decreases significantly due to water-sensitive damage, water locking, and bentonite and polymer molecule plugging. However, higher gas pressure can increase the permeability of contaminated coal samples. The intrusion of water and solid phase into coal samples reduces the influence of stress on permeability. This research has theoretical and practical significance in supporting the reformation of underground pressurized drilling methods and drilling fluid design.
NATURAL RESOURCES RESEARCH
(2023)
Article
Geosciences, Multidisciplinary
Tengfei Cao, Zhaobiao Yang, Yong Qin, Zhiming Yan, Zhaoying Chen, Chao Li
Summary: The study analyzed the vertical distribution characteristics of modern in situ stress and its impact on permeability in the Yangquan mining area based on injection pressure drop test data and acoustic emission test data. The results indicated different stress zones within burial depths, corresponding to variations in permeability. The study also explored the exploitation of the No. 15 coal reservoir and found that the permeability was influenced by various stress factors.
NATURAL RESOURCES RESEARCH
(2021)
Article
Geosciences, Multidisciplinary
Lei Zhang, Mengqian Huang, Mingxue Li, Shuo Lu, Xiaochuan Yuan, Jinghua Li
Summary: Mining of upper multilayers in deep coal seams generates cyclic loading-unloading stresses in bottom layers, which improve permeability and enhance coalbed methane gas drainage. Testing showed that permeability increased approximately by 5.8 times after loading-unloading cyclic tests. Different numbers of loading-unloading cycles produced similar fracturing effects, with the largest effect occurring within the effective stress range of 4 to 11 MPa.
NATURAL RESOURCES RESEARCH
(2022)
Article
Geosciences, Multidisciplinary
Fang Lv, Ruidong Yang, Tongsheng Yi, Wei Gao, Xu Wang, Wei Cheng, Yan Zhang, Ronglei Li, Zhihua Yan, Yaohui Liu, Geng Li
Summary: In-situ stress plays a crucial role in the selection of coalbed methane exploration areas and affects the production capacity of coalbed methane wells. This study focuses on the relationships between parameters such as pore pressure, closure pressure, breakdown pressure, in-situ stress, coal permeability, and depth. The distribution of different in-situ stress states and a simplified model diagram of triaxial principal stress and depth are proposed. The control of in-situ stress on coal reservoir permeability is explored, and a strong positive correlation is found between permeability and lateral pressure coefficient k-values at shallow depths. The study also reveals a new relationship between permeability and effective in-situ stress that differs from previous studies.
FRONTIERS IN EARTH SCIENCE
(2023)
Article
Geochemistry & Geophysics
Ruijing Zhu, Rongxi Li, Xiaoli Wu, Xiaoli Qin, Bangsheng Zhao, Futian Liu, Di Zhao
Summary: This study investigated the fluid inclusions in the Permian sandstone and Ordovician dolomite reservoirs in the central-southern Ordos Basin, finding two phases of fluid inclusions that recorded the history of natural gas formation and accumulation. The diagenetic fluids in these reservoirs showed medium-low temperature and moderate-low salinity, with natural gas accumulation being related to the Yanshanian tectonic movement.
Article
Engineering, Geological
Shirong Cao, Zhaolong Ge, Di Zhang, Zhe Zhou, Yiyu Lu, Hanyun Zhao
Summary: This study investigates the rock-breaking mechanism and pore structure evolution of typical reservoir rocks under ultra-high pressure water jet (UHP-WJ) impingement. The results show that different types of rocks exhibit different fracture mechanisms and pore structure evolutions under UHP-WJ impact. These findings provide important theoretical references for optimizing the development of unconventional natural gas reservoirs.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2022)
Article
Chemistry, Physical
Yee-Kwong Leong, Pengfei Liu, Peta Clode, Jishan Liu
Summary: Recent artifact-free microstructure information has led to the development of a more credible model for explaining the ageing time-dependent rheological behavior of NaMt, hectorite, and Laponite gels. The interplay of forces, including the EDL repulsive force, governs the formation of the 3-D network structure in these gels, which trap a significant amount of water in interconnected nanopores.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2021)
Article
Energy & Fuels
Jianwei Tian, Jishan Liu, Derek Elsworth, Yee-Kwong Leong, Wai Li, Jie Zeng
Summary: Researchers characterized the structural heterogeneity of hydrofractured shale reservoirs at different hierarchical levels, including nanopore structure, micro-structure, natural fracture networks, and hydraulic fractures. The study demonstrated significant impacts of these heterogeneities on gas production.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Energy & Fuels
Yifan Huang, Jishan Liu, Derek Elsworth, Yee-Kwong Leong
Summary: Conventional dual porosity/permeability models for coal cannot accurately capture the transient nature of matrix-fracture mechanical interactions. In this study, a new model is proposed that includes the transient process in the matrix system through the embedment of a local representative elementary volume (REV) structure. The model is verified against experimental observations of coal permeability under constant confining pressure and constant effective stress conditions, and the results show that conventional equilibrium models underestimate the role of coal matrix or matrix-fracture mechanical interactions.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2022)
Article
Energy & Fuels
Wai Li, Jishan Liu, Jie Zeng, Yee-Kwong Leong, Derek Elsworth, Jianwei Tian
Summary: This study developed a multidomain and multiphysics model to improve the simulation accuracy and obtain insights into coalbed methane (CBM) extraction. The model successfully coupled different physical processes and stimulation patterns to better understand CBM extraction. The findings suggest that the properties of different domains and the thermal effects can significantly influence CBM production, and increasing fracture complexity and improving stimulation techniques can enhance CBM recovery.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Energy & Fuels
Jianwei Tian, Jishan Liu, Derek Elsworth, Yee-Kwong Leong, Wai Li
Summary: The fractal nature of coal pore sizes affects both coal absolute and relative permeabilities. This study employs the fractal theory to derive new relative permeability models and conducts sensitivity studies to understand the impact of fractal dimensions on gas production.
Review
Energy & Fuels
Qi Gao, Jishan Liu, Yifan Huang, Wai Li, Rui Shi, Yee-Kwong Leong, Derek Elsworth
Summary: The evolution of coal permeability is complex and has led to the development of numerous models. Despite efforts to evaluate these models, the reasons for discrepancies between observations and predictions have not been identified. This study examines the models and concludes that they can be categorized into equilibrium and non-equilibrium models based on the internal structure of coal, boundary conditions, and equilibrium state. It is found that the exclusion of equilibration process is the root cause of discrepancies and suggests future research should integrate rock structure, boundary conditions, and equilibration process in coal permeability models.
Article
Energy & Fuels
Wai Li, Jishan Liu, Jie Zeng, Yee-Kwong Leong, Derek Elsworth, Jianwei Tian
Summary: This study proposes the concept of kerogen threshold differential pressure (KTP) to describe the influence of water on gas liberation from kerogen. A fully coupled, multidomain, and multiphysics model is developed to simulate gas extraction from stimulated shale reservoirs, and a sensitivity analysis is performed to investigate the effects of important factors.
Article
Chemistry, Physical
Yee-Kwong Leong, Pengfei Liu, Jishan Liu, Peta Clode, Weian Huang
Summary: Composite NaMnt (SWy-2)-kaolin (KGa-2) gels with more than 10 wt% solids and a NaMnt fraction of 20% exhibit an open cellular microstructure. The flexible nanosized NaMnt platelets form a continuous structure with dispersed kaolin particles, resulting in various unique particle interaction configurations. The study also reveals the thixotropic and rheopectic behaviors of a 15.5 wt% gel with a 1:2 mass ratio of NaMnt to kaolin. Evaluation of the gel's structural development kinetics and aging behavior further provide insights into the formation process of continuous structures. Rating: 8/10.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2023)
Article
Energy & Fuels
Jianwei Tian, Jishan Liu, Derek Elsworth, Yee-Kwong Leong, Wai Li
Summary: In this study, a dual-fractal permeability model was proposed to investigate the impacts of coal internal structure on permeability. The model considers the effects of pore-fracture size distribution and effective stress, and incorporates multiple flow mechanisms.
Article
Chemistry, Physical
E-Jen Teh, Yee-Kwong Leong
Summary: This study explains the cause of unusual behaviour in colloidal suspension and provides a new method to alleviate biofouling and scaling problems. The yield stress-pH behaviour of silica suspensions differs depending on the direction of pH change. Precipitate bridging is responsible for the yield stress, with composite precipitates formed by soluble silica and organic acid anions. The presence of fumarate and high pH enhances the yield stress, and avoiding a high pH operating environment can mitigate biofouling and scaling.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2023)
Review
Energy & Fuels
Qi Gao, Jishan Liu, Yee-Kwong Leong, Derek Elsworth
Summary: The significant effects of gas sorption induced swelling on shale permeability have been studied through laboratory measurements and explained using permeability models. However, there are lab observations that cannot be explained by these models, leading to a knowledge gap. In this review, the authors aim to resolve this gap by assessing the role of swelling on shale permeability through data collection, model classification, and correlation assessments. The findings suggest that discrepancies between model predictions and lab measurements depend on various factors, including the relationship between bulk and pore swelling strains, pore size scales, and consistency of strain treatments. The authors propose that future research should focus on characterizing the transformation between bulk and pore swelling strains, considering shale multiscale pore structural characteristics, and incorporating the time-dependent nature of swelling strain and permeability evolution.
Article
Construction & Building Technology
Huiyuan Liu, Mohamed Elchalakani, Sherif Yehia, Yee-Kwong Leong, Peng Du
Summary: This paper presents an experimental investigation on developing high-performance carbon nanotube (CNT) and fibre-reinforced ultra-lightweight cementitious composites (ULCC) using ordinary Portland cement (OPC), metakaolin (MK), polyethylene (PE) fibres, and ceno-spheres. The effects of CNT dosage, binder type, and PE fibres were investigated and discussed, and the resulting ULCC displayed impressive strength and density properties. The synergic effect of CNT was found to be better than the combination of CNT and PE fibres. The study also highlighted the cost implications of adding CNT to the mix.
DEVELOPMENTS IN THE BUILT ENVIRONMENT
(2023)
Article
Computer Science, Interdisciplinary Applications
Jianwei Tian, Jishan Liu, Derek Elsworth, Yee-Kwong Leong
Summary: In this study, a 3D discrete fracture model (DFM) was proposed to represent the distribution of natural fractures (NFs). Gas flow in shale matrix was represented by a dual-fractal permeability model (DFPM). A hybrid DFPM-DFM model was proposed to couple gas flow and geomechanics and solved using finite element method. The model was verified with field data and used to investigate the impacts of fractally-distributed pore size and fracture attributes on permeability evolution and gas production.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Energy & Fuels
Qi Gao, Jishan Liu, Yaoyao Zhao, Mingyao Wei, Yee-Kwong Leong, Derek Elsworth
Summary: Approximately 20% of global natural gas resources may be microbial in origin, leading to significant interest in extracting biogenic gas from coal seams. Previous studies have shown that this can be achieved through injecting nutrients solution into a coal reservoir, stimulating microbial growth and enhancing biodegradation of organic components into methane gas. In this study, a modeling tool is developed to validate this concept under laboratory and reservoir conditions, coupling various physical and biological processes. The model is verified against experimental data and applied to simulate practical operations, demonstrating the effectiveness of coal-to-methane bioconversion and extraction.
GEOENERGY SCIENCE AND ENGINEERING
(2023)
Article
Nanoscience & Nanotechnology
Gang Han, Bo Tan, Fei Cheng, Binhua Wang, Yee-Kwong Leong, Xiaozhi Hu
Summary: This study demonstrated a simple technique for enhancing adhesive bond strength between Al substrate and CFRP using pre-coating resin with CNTs. The interfacial shear bond strength was effectively increased by 30%-100% depending on the Al substrate surface profiles.
NANO MATERIALS SCIENCE
(2022)