Article
Environmental Sciences
Xiaoming Ni, Xuebin Tan, Sen Yang, Bin Xu, Xiaokang Fu
Summary: The evaluation of CBM production potential considering different coal structures can better reflect the objective facts, especially in areas with strong heterogeneity in coal structure. The proposed method provides a novel approach to accurately evaluate CBM production potential in regions with highly heterogeneous coal structures.
ENVIRONMENTAL EARTH SCIENCES
(2021)
Article
Thermodynamics
Yinbo Zhou, Hansheng Li, Jilei Huang, Ruilin Zhang, Shijie Wang, Yidu Hong, Yongliang Yang
Summary: Coal deformation affects pore pressure, fracture aperture, and gas Kn value, which in turn influences transitions between gas flow regimes.
Review
Energy & Fuels
Wancheng Zhu, Shuyuan Liu, Xiufeng Zhang, Chenhui Wei
Summary: This paper provides a comprehensive review of the mechanisms and properties of gas adsorption in coal, the geomechanical behavior of coal, and the mechanisms of gas transport in coal. It also discusses several waterless fracturing techniques for improving coalbed permeability and identifies current knowledge and research gaps.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2022)
Article
Engineering, Geological
Min Chen, Shakil Masum, Sivachidambaram Sadasivam, Hywel Thomas
Summary: This study proposes an effective stress model for investigating the anisotropy of coal swelling in fractured porous media. The model considers the change in stress on the solid-fluid interface induced by gas adsorption. Experimental results show that coal swelling is greater in the direction perpendicular to the bedding plane than in the parallel plane. The evolution of anisotropic stress-dependent permeability behavior is described by direction dependent fracture compressibility. The presented model provides a tool for quantifying gas adsorption-induced anisotropic coal swelling and permeability behaviors.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2022)
Article
Energy & Fuels
Jianhua Li, Heping Xie, Jun Lu, Mingzhong Gao, Bobo Li, Yan Wu
Summary: This study proposes a permeability model for anisotropic coal by combining gas sorption effects and three-dimensional stress compression, and quantitatively analyzes the effect of stress-induced fracture expansion on the fracture-matrix system. Seepage tests and measurements of coal, sandstone, and composite coal-rock were conducted, and the results show that stress first causes fracture compression, but with the continuous increase of stress, fracture initiation and expansion increase the seepage channel of rock and lead to a sudden increase in permeability.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2022)
Article
Energy & Fuels
Mingyao Wei, Chun Liu, Yingke Liu, Jishan Liu, Derek Elsworth, Osvaldo A. F. A. Tivane, Chao Li
Summary: Matrix shrinkage is the most important factor influencing the permeability evolution in coal reservoirs, which diminishes with uniform depressurization of the matrix. Sensitivity analysis on mechanical and flow properties shows that greater matrix shrinkage-induced strain leads to higher permeability enhancement.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Energy & Fuels
Jie Zhu, Jun Tang, Chenyu Hou, Tangsha Shao, Yuhan Zhao, Jinge Wang, Li Lin, Jinjia Liu, Yaodong Jiang
Summary: Fluid flow modeling of coalbed methane wells is crucial for predicting gas production and designing effective depressurization schemes. Hydraulic fracturing plays a significant role in improving reservoir permeability. The numerical simulation results in this study show that considering the permeability evolution between different areas is essential for accurately estimating CBM well production.
Article
Construction & Building Technology
Dong Wang, Tie Li, Zhiheng Cheng, Weihua Wang
Summary: The study investigated the effect of cyclic loading on the pore structure of coal, revealing that increasing loading frequency promotes the formation and development of pores and fractures, as well as driving the transformation of micropores and transition pores into mesopores and macropores, increasing the proportion of seepage pores. Meanwhile, large loading amplitudes reduce the volume of seepage pores by subjecting macropores and mesopores to repeated external force.
ADVANCES IN CIVIL ENGINEERING
(2021)
Article
Chemistry, Multidisciplinary
Lufei Wang, Xianbo Su, Weizhong Zhao, Daping Xia, Qian Wang
Summary: The study found that supercritical CO2 extraction combined with anaerobic digestion can promote biomethane production by increasing the metabolic efficiency of intermediates and reducing the content of carbonyl and carboxyl groups on the coal surface. The microbial community structure in the supercritical CO2-assisted anaerobic digestion system was more stable and efficient compared to the anaerobic digestion system alone. This research demonstrates the potential of supercritical CO2 extraction for enhancing coalbed methane recovery and reducing CO2 emissions.
JOURNAL OF CO2 UTILIZATION
(2023)
Article
Geosciences, Multidisciplinary
Qixian Li, Jiang Xu, Shoujian Peng, Fazhi Yan, Bin Zhou, Ende Han, Cheng Jiang
Summary: Coalbed methane co-production technique was explored in this study, revealing the pressure equilibrium and gas flow between different coal reservoirs. The study further demonstrated the dynamic supply state in coalbed methane production, enabling effective management and optimization of production efficiency.
NATURAL RESOURCES RESEARCH
(2021)
Article
Energy & Fuels
Chao Xu, Gang Yang, Kai Wang, Qiang Fu
Summary: This study focused on the permeability of coal reservoirs in China and how to increase it for coalbed methane drainage. Through field measurements and numerical simulations in Baode coal mine, the study proposed a targeted CBM drainage method that achieved good results in practice.
Article
Energy & Fuels
Yun Yang, Shimin Liu
Summary: The exploitation of coalbed methane plays a crucial role in meeting natural gas demand and reducing greenhouse gas emissions, but many resources remain undeveloped. Accurate production forecasting is essential to increase and sustain CBM recovery. Current computational models underestimate long-term production performance, while a multi-scale CBM model can improve production rates and extend productive lifetimes.
Article
Energy & Fuels
Peng Liu, Ang Liu, Fangxiang Zhong, Yongdong Jiang, Jiajun Li
Summary: The study demonstrates the significant improvement of coal porosity and permeability through ultrasonic treatment, with potential benefits for gas desorption/diffusion within the coal matrix. The results show that the ultrasonic performance on permeability improvement is proportional to treatment time, but has time threshold effect on ultrasonic fracturing in stressed coal.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Energy & Fuels
Guanglei Cui, Wangxing Cheng, Wei Xiong, Tianyu Chen, Yong Li, Xia-Ting Feng, Jishan Liu, Derek Elsworth, Zhejun Pan
Summary: The co-production of gas from coalbeds and tight formations is a viable means to improve well productivity. However, previous studies have not paid much attention to the effectiveness of gas co-production with regard to well types. In this study, a coupled model is proposed to analyze the impacts of gas co-production and different reservoir interactions. The results provide recommendations for the use of horizontal or vertical wells based on the characteristics of the reservoirs and well life.
Article
Engineering, Geological
Xuehai Wu, Bobo Li, Chonghong Ren, Zheng Gao, Jiang Xu, Yao Zhang, Chunhong Yao
Summary: Coal and gas outburst is one of the main gas energy disasters in coal mines. Pre-extraction of coal-bed methane (CBM) is an effective method to reduce the outburst risk. However, coal mining and CBM extraction can cause plastic deformation or failure in coal, leading to changes in gas migration behavior. This study developed a coupled damage-permeability model based on elastoplastic mechanics in coal to study the permeability characteristics and mechanical properties of coal under engineering disturbance. The model was verified through experiments and showed good agreement with experimental results. The proposed model provides a theoretical basis for coal mine gas disaster prevention and CBM extraction.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
Bin Zhang, Yafei Zhang, Suping Zhao, Wei He, Shu Tao, Zhejun Pan, Yi Cui
Summary: This study conducted CH4 isothermal adsorption measurements on 64 coal samples from western Guizhou Province in China and quantitatively analyzed the desorption processes of coalbed methane (CBM). The results indicate that coalification affects the Langmuir volume and pressure, which tend to increase with higher vitrinite reflectance. The CBM desorption process was divided into four stages (inefficient, slow, fast, and sensitive) using three key pressure nodes. The fast and sensitive desorption stages are crucial for achieving high gas production.
FRONTIERS OF EARTH SCIENCE
(2023)
Article
Engineering, Geological
Jun Zhang, Qiangang Yu, Yuwei Li, Zhejun Pan, Bo Liu
Summary: This study investigates the vertical propagation mechanism of hydraulic fractures in interlayered brittle shale formations. Experimental modeling and quantitative analysis are conducted to study the effects of geological and engineering factors on fracture propagation behavior. The results show that interlayer dip angle, vertical in situ stress difference, and interface cementation strength are important factors affecting fracture propagation. The brittleness characteristics of the interlayer also have a significant impact. The findings provide a deeper understanding of fracture geometry and the fracture intersection mechanism, offering accurate guidance for fracturing parameter optimization.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
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
Jie Zeng, Jianchun Guo, Jishan Liu, Wai Li, Yingfang Zhou, Jianwei Tian
Summary: A fully anisotropic coal permeability model is established, incorporating stress sensitivity, anisotropic internal swelling/shrinkage, and gas rarefaction effects. The model's reliability is demonstrated through comparisons with coal anisotropic swelling data and anisotropic permeability evolution data. Results show that anisotropic internal swelling/shrinkage mainly determines the overall shape, evolution trend, range of permeability change, and anisotropy level of permeability curves.
Article
Energy & Fuels
Xingxing Liu, Liang Chen, Jinchang Sheng, Jishan Liu
Summary: In this study, a concept of local non-equilibrium index (LNEI) is proposed to define a complete permeability model under the influence of gas extraction/injection. The non-equilibrium model takes into account the transient nature of local equilibration evolution and is able to explain permeability data more accurately. The model is verified against experimental data and applied to predict the effects of local equilibration on coal permeability and gas production under field conditions.
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
Geosciences, Multidisciplinary
Hongyan Qu, Yan Peng, Zhejun Pan, Xiangdong Xu, Fujian Zhou
Summary: Water-flooding is an effective method for developing extra-low permeability oil reservoirs, but water-rock interactions can alter geomechanical properties and impact the propagation of water-flooding induced fractures (WIFs). This study proposes a method to calculate WIF propagation length and establishes numerical models considering the effect of water-rock interactions. The models are validated and the mechanism and impact of water-rock interactions on WIF propagation are analyzed.
FRONTIERS IN EARTH SCIENCE
(2023)
Article
Thermodynamics
Ruirui Li, Luqing Zhang, Jian Zhou, Zhenhua Han, Zhejun Pan, Holger Schuettrumpf
Summary: This study investigates the influence of mineral particle shape and pore-filling natural gas hydrate (NGH) on permeability anisotropy. Simulation methods are used to construct numerical samples and calculate anisotropic permeabilities. The results show that elongated particles have minimal effect on permeability anisotropy, while preferential alignment of plate-shaped particles is the main cause. Understanding the formation mechanism of permeability anisotropy has potential applications in NGH exploitation, groundwater environment protection, and geological disaster prevention.
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
Energy & Fuels
Zhao Yaoyao, Zhao Yixin, Liu Jishan, Wei Mingyao, Cui Dongxue, Gao Sen
Summary: Permeability is a key parameter for evaluating the ability of coal reservoirs to transmit coalbed methane. The deformations of coal caused by physical field variations control the permeability evolution, and there is obvious non-uniformity in the deformations due to coal heterogeneity. However, the relationship between non-uniform deformation and permeability is unclear. This study conducted experiments to measure the permeability and deformations of a coal sample under different boundary conditions and injection pressures. The results showed anisotropic mechanical properties of the coal sample and differences in deformations between coal bulk and fractures.
Review
Geosciences, Multidisciplinary
Changqing Fu, Yi Du, Wenlei Song, Shuxun Sang, Zhejun Pan, Ning Wang
Summary: Automated Mineralogy (AM) is a semi-automatic mineralogical tool that uses a scanning electron micrography-energy dispersion spectrometry (SEM-EDS) platform. It can analyze sedimentary environments, diagenetic evolution processes, and evaluate oil and gas reservoirs. The combination of AM and CT scanning can improve the accuracy of mineral distribution and be applied to study fluid reactive transport effects.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Engineering, Chemical
Duo Wang, Sanbai Li, Dongxiao Zhang, Zhejun Pan
Summary: The transport mechanism of densely-packed proppant bed is numerically investigated using the lattice Boltzmann-discrete element coupling method (LB-DEM). This study focuses on the bedload transport of settled proppants in the primary fracture. The results show a nonlinear relationship between particle flux and fluid flux, which is attributed to the shear-thinning property of the proppant bed. The research contributes to an improved hydraulic fracturing operation by optimizing the fracturing fluid injection scheme and proppant flowback control.
Article
Energy & Fuels
Yaoyao Zhao, Yixin Zhao, Jishan Liu, Mingyao Wei, Yifan Huang, Chuanzhong Jiang
Summary: In this study, a new multi-physical field coupling model was established to accurately predict the non-uniform deformation between coal bulk and fractures. Three kinds of non-uniform deformation indexes were defined and the theoretical solutions of the model were validated with experimental results. Additionally, the concept of modified effective stress was proposed to address the inconsistency between theoretical and experimental permeability solutions under constant effective stress condition.
Review
Energy & Fuels
Biao Hu, Yuanping Cheng, Zhejun Pan
Summary: The pore structures in coal are crucial for the occurrence and migration of coalbed methane (CBM), which plays a significant role in CBM extraction, utilization, and coal mining disaster prevention. Existing pore classification methods for coal have their drawbacks, thus this paper systematically reviews previous methods and proposes a new pore classification based on the characteristics of CH4 occurrence and migration in coal. This new method categorizes pore structures into four types and provides a more intuitive understanding of CBM occurrence and migration.
GAS SCIENCE AND ENGINEERING
(2023)
Review
Energy & Fuels
Qing Liu, Mengdi Sun, Xianda Sun, Bo Liu, Mehdi Ostadhassan, Wanxia Huang, Xiaoxia Chen, Zhejun Pan
Summary: X-ray computed tomography (X-ray CT) scanning is a non-destructive visualization technology that can be used to characterize multiscale shale pore structures and assess their permeability. Various imaging techniques, such as micro-CT, nano-CT, FIB-SEM, and contrast agent injections, provide a powerful approach for evaluating shale microstructures. Additionally, digital rock physics (DRP) based on 3D visualization can be used for flow modeling and predicting transport properties. CT scanning can also capture the significant evolution of microstructures during geological processes or hydrocarbon exploitation.
GAS SCIENCE AND ENGINEERING
(2023)
