Article
Energy & Fuels
Ruiyue Yang, Haitao Wen, Zhongwei Huang, Bo Zhang, Haizhu Wang, Bin Wang, Nikita Dubinya
Summary: A new compound fracturing method combining liquid nitrogen (LN2) fracturing and hydraulic fracturing is proposed in this study to improve the efficiency of hydraulic fracturing in coalbed methane (CBM) reservoirs. Lab results show that the compound fracturing method can create more complex and highly conductive fracture networks compared to traditional fracturing methods.
Article
Engineering, Geological
Peng Hou, Shanjie Su, Feng Gao, Xin Liang, Shengcheng Wang, Yanan Gao, Chengzheng Cai
Summary: The role of LN2 cooling in the fracturing process of coal and its effects on the mechanical properties and fracture behaviors of the coal samples have been investigated through laboratory experiments and numerical simulations.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
Zhiwei Liao, Xianfeng Liu, Dazhao Song, Xueqiu He, Baisheng Nie, Tao Yang, Longkang Wang
Summary: The technology of liquid carbon dioxide phase change fracturing (LCPCF) was used to enhance the permeability of coal seams. LCPCF had mechanical damage effects on coal micro-structures to varying degrees. HP-MIP results showed that LCPCF mainly affected pores of > 100 nm within coal and resulted in the increase in the number of macro-pores and micro-fractures.
NATURAL RESOURCES RESEARCH
(2021)
Article
Mechanics
Songcai Han, Qi Gao, Junchao Yang, Lei Wang, Yuanfang Cheng, Chuanliang Yan, Xian Shi
Summary: A fully coupled thermo-hydro-mechanical (T-H-M) model combined with the statistical meso-damage theory is proposed to investigate the trans-scale progressive cracking process of shale gas reservoirs stimulated by liquid nitrogen (LN2). Numerical results demonstrate that fracturing using LN2 can generate fractures with lower initiation pressure and greater complexity compared with H2O and supercritical CO2. Preliminary results confirm the potential of using LN2 fracturing to improve the stimulation effect of shale reservoirs.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Energy & Fuels
Lei Qin, Chao Ma, Shugang Li, Haifei Lin, Ping Wang, Hang Long, Dongjie Yan
Summary: Cracking low-permeability coal seams with anhydrous liquid nitrogen can enhance coalbed methane extraction efficiency, but freezing variables significantly affect the mechanical properties of coal, with an increase in freezing cycles leading to a decrease in mechanical strength.
Article
Engineering, Geological
Hai Qu, Zhelun Li, Chengying Li, Xu Liu, Zhijun Zeng, Yang Xu, Ying Liu
Summary: This study investigates the fracturing performances of liquid nitrogen (LN) in low-brittle shales with bedding planes. It was found that LN fracturing can lower fracture initiation pressure and promote fracture propagation compared to hydraulic fracturing. Moreover, LN can thermally induce fractures and deteriorate shale structure.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Engineering, Geological
Hai Qu, Shimao Tang, Ying Liu, Pengpeng Huang, Xiaoguang Wu, Zhonghua Liu, Chengying Li
Summary: The study shows that using liquid nitrogen (LN2) for shale fracturing can decrease the breakdown pressure, activate pre-existing fractures and bedding planes, and enhance formation permeability. Lower stress anisotropy, higher pumping rate, and lower bedding plane angle result in more complex fractures.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Energy & Fuels
Shengcheng Wang, Shanjie Su, Dengke Wang, Peng Hou, Yi Xue, Xin Liang, Chengzheng Cai, Xianghe Gao, Yuhao Jin, Shuo Yang, Xuan Jiang
Summary: Liquid nitrogen fracturing is expected to be an effective method for increasing coalbed methane production due to its good reservoir adaptability. The advantages of ultra-low temperature and high gasification pressure during the fracturing process need further exploration.
GEOMECHANICS FOR ENERGY AND THE ENVIRONMENT
(2023)
Article
Geosciences, Multidisciplinary
Shuai Chen, Linming Dou, Lei Zhang, Jingbo Song, Jianping Xu, Zepeng Han
Summary: The use of LN2 cyclic fracturing technology can effectively reduce the bursting liability of coal samples by causing deterioration, lowering P-wave velocity, and increasing porosity. After LN2 cyclic treatment, the coal samples showed significantly lower bursting liability, increased dynamic fracture duration time (DFDT), and a stepped pattern in the post-peak phase of load-time curves. The UCS and BEI of coal samples decreased significantly after four LN2 fracturing cycles, while the ESEI declined. The AE activities of coal samples during LN2 cycles can be classified into different stages, and the failure mode of coal samples transformed from dynamic failure to static failure.
NATURAL RESOURCES RESEARCH
(2023)
Article
Geosciences, Multidisciplinary
Lei Qin, Siheng Lin, Haifei Lin, Shugang Li, Pengxiang Zhao, Weikai Wang, Zitong Xue
Summary: Studying the ice-water phase transition process of frozen coal is key to break through the theory of cryogenic mining technology.
NATURAL RESOURCES RESEARCH
(2022)
Article
Engineering, Geological
Yi Ren, Vaclav Vavrycuk, Shunchuan Wu, Yongtao Gao
Summary: The study found that weighted inversion and STC inversion work better than the standard least-squares method. Additionally, when the study object contains significant non-double-couple components of moment tensors, the STC inversion proved to be most accurate.
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
(2021)
Article
Energy & Fuels
Chengzheng Cai, Zhixiang Tao, Keda Ren, Shuang Liu, Yugui Yang, Yinrong Feng, Shanjie Su, Peng Hou
Summary: Liquid nitrogen (LN) fracturing has been proven to be an efficient technology for developing unconventional gas resources. Experimental results showed that increasing the initial rock temperature reduces the breakdown pressure of sandstone, while under cryogenic conditions, the fracture complexity is significantly improved despite a potential increase in breakdown pressure.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Energy & Fuels
Zuliang Shao, Shen Ye, Siji Tao, Xuewei Feng, Yong Wang
Summary: The study found that LN2 penetration has a significant impact on the damage of dry coals, but a lesser impact on the damage of saturated coals. Dry samples with LN2 penetration showed significantly increased size and number of micro-fractures, while saturated samples exhibited more severe damage.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Engineering, Geological
Egor Dontsov
Summary: The purpose of this study is to investigate the morphology of simultaneously propagating hydraulic fractures from a horizontal well. The findings show that stress interaction between the fractures affects their shapes, with different parameters having different impacts.
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS
(2022)
Article
Multidisciplinary Sciences
Wei-Yao Guo, Wei Zhang, Cheng-Guo Zhang, Yang Chen
Summary: This paper presents an experimental study on the behavior of coal samples under tensile loadings to understand the failure mechanisms and interactions with coal characteristics. The study found that the loading process mainly consists of compaction, elastic, and post-peak dropping stages. Two types of deformation localisation and different phases of acoustic emission evolution were observed. During the subcritical failure stage, the acoustic emission counts showed a rapidly increasing and intermittent feature.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Physical
Yi Xue, Jia Liu, Xin Liang, Xue Li, Songhe Wang, Zongyuan Ma, Shaowei Zhang, Xuanye Jiao
Summary: As the simplest saturated hydrocarbon, methane plays a crucial role in hydrogen and carbon energy. Maintaining the stability and sealing of caprock is essential for safe underground storage of energy. A fully coupled two-phase flow model is established to study the migration mechanism of methane in caprock, considering the characteristics of the dual porosity medium. The model incorporates methane and brine seepage in the fracture network and the dynamic adsorption-desorption process in the matrix.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Engineering, Geological
Yi Xue, P. G. Ranjith, Feng Gao, Zhizhen Zhang, Songhe Wang
Summary: The mechanical behavior of coal under different gas pressures was investigated in this study. The influence of gas pressure on the mechanical properties of coal and the energy input and dissipation during loading were analyzed. The effects of gas pressure on coal strength were also theoretically analyzed. The results show that the absorbed energy in the axial pressure direction accounts for the main proportion of the total absorbed energy by coal.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Article
Energy & Fuels
Yi Xue, P. G. Ranjith, Yang Chen, Chengzheng Cai, Feng Gao, Xingguang Liu
Summary: Geological sequestration of CO2 is important for reducing global warming and achieving carbon neutralization. This study evaluates the effect of CO2 adsorption pressure on the mechanical properties of coal mass using experimental and analytical methods. An elastic damage model is established to describe the nonlinear stress-strain relationship of coal under CO2 adsorption. The results show that increasing adsorption pressure increases the risk of coal damage and fracturing, leading to a more complex fracturing process.
Article
Energy & Fuels
Shengcheng Wang, Shanjie Su, Dengke Wang, Peng Hou, Yi Xue, Xin Liang, Chengzheng Cai, Xianghe Gao, Yuhao Jin, Shuo Yang, Xuan Jiang
Summary: Liquid nitrogen fracturing is expected to be an effective method for increasing coalbed methane production due to its good reservoir adaptability. The advantages of ultra-low temperature and high gasification pressure during the fracturing process need further exploration.
GEOMECHANICS FOR ENERGY AND THE ENVIRONMENT
(2023)
Article
Energy & Fuels
Yi Xue, Shuai Liu, Junrui Chai, Jia Liu, P. G. Ranjith, Chengzheng Cai, Feng Gao, Xue Bai
Summary: Deep geothermal energy exploitation involves using an enhanced geothermal system (EGS) to extract heat from hot dry rock (HDR) through hydraulic fracturing technology. A thermal-hydraulic-mechanical coupling model is proposed to study the effects of water-cooling shock on fracture initiation and morphology in HDR hydraulic fracturing. The results show that water-cooling shock can significantly reduce fracture initiation pressure, induce more secondary fractures, and form complex fracture networks, with initial rock temperature and heat transfer coefficient affecting fracture morphology.
Article
Geochemistry & Geophysics
Linchao Wang, Yi Xue, Zhengzheng Cao, Xiao-juan Wu, Fa-ning Dang, Ruifu Liu
Summary: The cooling characteristics of liquid nitrogen can weaken the mechanical properties of dry hot rock reservoirs and improve the porosity and permeability. Uniaxial compression tests, Brazil splitting tests, three-point bending tests, and synchronous acoustic emission tests were conducted on high-temperature granite to investigate the weakening effect of liquid nitrogen cooling characteristics. The results showed that liquid nitrogen significantly decreased the elastic modulus, peak strength, and fracture toughness of granite, and its damage effect varied with the initial temperature of the rock.
Article
Geochemistry & Geophysics
Xue Li, Yi Xue, Fa-ning Dang, Zhihao Zhang, Lin Zhu, Shanjie Su, Shengcheng Wang, Ruifu Liu
Summary: Due to the depletion of resources and reduction of available space, human beings have started to explore deep underground areas. This expansion raises safety concerns, particularly regarding rockburst. This study conducted laboratory tests and analyzed relevant literature and research to investigate the characteristics of granite under the influence of liquid nitrogen (LN2) and study its fracture mode. The results showed that LN2 cooling negatively affects the strength of the rock, and the elastic modulus and peak stress of granite decrease with increasing cycles. The AE ring count, frequency, and amplitude of energy of granite increased with the number of LN2 cycles. The AE parameters characterized two failure modes of the rock: tensile and shear failure. The tendency index of rockburst decreased with decreasing elastic modulus, and the repeated action of LN2 reduced the probability of rockburst to some extent.
Article
Geochemistry & Geophysics
Xue Li, Yi Xue, Zhihao Zhang
Summary: In this study, a numerical simulation model is established to analyze the water inrush mechanism in underground engineering. The analysis considers factors such as aquifer pressure, permeability, and the fluid-solid coupling effect. The study provides effective suggestions for preventing water inrush and proposes preventive measures such as drainage grouting. Overall, this research provides important insights into the causes and effects of water inrush from faults and can inform practical measures to mitigate risks associated with underground engineering.
Article
Geochemistry & Geophysics
Yuhe Cai, Yi Xue, Faning Dang, Linchao Wang, Xue Li, Shanjie Su, Shengcheng Wang, Xinyu Liang, Shaowei Zhang
Summary: This study investigates the effects of liquid nitrogen cyclic treatment on coal samples from Jiaozuo area using Brazil's indirect tensile testing. The results show that liquid nitrogen significantly influences the formation and development of coal fractures. The study also reveals that the maximum load-bearing capacity of coal decreases with an increased number of cyclic treatments, indicating a reduction in effective stress on coal samples. Furthermore, the acoustic emission activity intensity of coal mass increases with the number of freeze-thaw cycles of liquid nitrogen.
Article
Engineering, Geological
Yanan Gao, Donghao Lan, Shengqi Yang, Peng Hou, Yunlong Wang, Feng Ding
Summary: A series of mechanical tests and acoustic emission (AE) monitoring were conducted to investigate the effects of disturbance stress paths, disturbance modes, and initial confining pressures (ICPs) on the behavior of engineering rocks. The fractal dimensions of AE temporal distribution (Dt) and spatial distribution (Ds) were calculated and analyzed, along with the normalized AE count. The results showed that the different disturbance modes had sensitive, inferior sensitive, and delayed sensitive effects on the AE activities, depending on the ICP. The damage severity of the disturbance modes followed the order of HD, MD, and LD modes under an ICP of 12.5 MPa. The changes in Dt and Ds were consistent with the sensitive effect. Under an ICP of 25 MPa, only the HD mode caused significant damage, while the LD and MD modes showed inferior sensitive effects. Similarly, under an ICP of 37.5 MPa, the late-period Ds showed significant differences among the three disturbance modes, indicating delayed sensitive effects. Overall, the study revealed that the damage propagation and mechanical behavior of engineering rocks were influenced by both the ICP and disturbance mode.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Geochemistry & Geophysics
Linchao Wang, Yi Xue, Xuyang Shi, Zhihao Zhang, Xue Li, Lin Zhu, Ruifu Liu, Lin Sun, Caifang Wu, Songbao Feng, Yu Wang
Summary: The utilization of liquid nitrogen as a sustainable and water-free fracturing medium shows great promise in engineering applications. This study investigates the impact of liquid nitrogen cooling on the internal structure and mechanical properties of rocks using Brazilian split tests and acoustic emission tests. The findings reveal that high-temperature liquid nitrogen treatment significantly modifies the microscopic structure and mechanical properties of rocks, potentially affecting their overall stability and reliability.
Article
Environmental Sciences
Linchao Wang, Yi Xue, Zhengzheng Cao, Hailing Kong, Jianyong Han, Zhizhen Zhang
Summary: Liquid nitrogen fracturing is an important technique for the development of geothermal energy, promoting fracture formation and heat exchange in hot dry rocks. The study shows that cycling cooling with liquid nitrogen leads to a decrease in rock strength, an increase in energy release, and surface roughness of granite, thus promoting the formation of internal fractures.
Review
Materials Science, Multidisciplinary
Lin Zhu, Weihua Ding, Faning Dang, Guochen Sang, Yi Xue, Qiaoyu Wang
Summary: This paper investigates the thermal conductivity and pore characteristics of lightweight aggregate concrete (LWAC) with microencapsulated phase change materials (MPCM). Experimental and theoretical investigations reveal a clear relationship between pore characteristics and MPCM dosage. An improved theoretical model is proposed to consider the impact of pore characteristics on the effective thermal conductivity (ETC) of MPCM-LWAC. The experimental and theoretical results demonstrate the effectiveness of the improved model in predicting the ETC of MPCM-LWAC.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2023)
Article
Multidisciplinary Sciences
Jia Liu, Yi Xue, Xin Liang, Songhe Wang
Summary: A particle-tracing method is proposed to investigate proppant reflux phenomena in hydraulically induced fractures during fracturing fluid flowback. The study explores the effects of fracture roughness on proppant particle migration.
ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING
(2023)
