Article
Energy & Fuels
Kang Chen, Xianfeng Liu, Longkang Wang, Dazhao Song, Baisheng Nie, Tao Yang
Summary: The influence of supercritical CO2 (SC-CO2) fluids on coal pore structure and mineral content is significant, leading to reductions in micropore volume, increases in average pore diameter and macropore volume, as well as alterations in mineral content. The impact of SC-CO2 is related to coal rank, with the greatest effect on lignite's macropore volume and anthracite's micropore volume. Mineral dissolution may contribute to the reduction in micropores and increase in mesopores and macropores.
Article
Thermodynamics
Kang Chen, Xianfeng Liu, Baisheng Nie, Chengpeng Zhang, Dazhao Song, Longkang Wang, Tao Yang
Summary: CO2 injection into coal seams enhances coalbed methane recovery and achieves CO2 geological sequestration. Supercritical CO2 (SC-CO2) interactions with coal alter pore structure and mineral compositions, increasing gas adsorption and storage capacity.
Article
Energy & Fuels
Wenfeng Guang, Xiaoqian Liu, Zhenyu Zhang, Peng Luo
Summary: The diffusion mechanism of CH4 and CO2 on the coal matrix is important for enhanced coal seam gas recovery and CO2 sequestration. Different-phase CO2 has different effects on gas mass transfer and surface thermodynamics in the coal matrix.
Article
Thermodynamics
Chaolin Zhang, Enyuan Wang, Bobo Li, Xiangguo Kong, Jiang Xu, Shoujian Peng, Yuexia Chen
Summary: CO2-ECBM recovery has the triple benefits of recovering clean resources, ensuring coal mine safety, and achieving CO2 geological sequestration. The study reveals that during CO2-ECBM recovery, the reservoir pressure remains high, methane recovery efficiency increases, but CO2 sequestration efficiency decreases with increasing injection pressure. A displacement index is proposed to reflect the synergistic effect of methane recovery and CO2 sequestration, and a dynamic pressure injection mode is suggested to enhance recovery and sequestration efficiency.
Article
Geochemistry & Geophysics
Renxia Jiang, Hongguan Yu
Summary: Supercritical CO2 (Sc-CO2) extraction from coal results in the extraction of hydrocarbons, oxygen-containing compounds, and sulfur-containing compounds. The main components are hydrocarbons, specifically acyclic alkanes and alkenes. Oxygen-containing compounds include esters and carboxylic acids, while sulfur-containing compounds are present in low concentrations. Extraction becomes more difficult with higher coal ranks.
Article
Geosciences, Multidisciplinary
Run Chen, Kunpeng Hu, Fengrong Lv, Yajun Zhang
Summary: In this study, coal samples were selected from the eastern margin of Ordos Basin to simulate supercritical CO2 (Sc-CO2) extraction and investigate the changes in pore structure and porosity. The results showed significant changes in pore volume, pore specific surface area, and connectivity characteristics due to Sc-CO2 extraction, with a turning point near the second coalification. The study also established a variation model for the pore structure of coal due to Sc-CO2 extraction. This research provides important insights for the understanding of CO2-enhanced CBM (CO2-ECBM) mechanism and engineering.
FRONTIERS IN EARTH SCIENCE
(2023)
Article
Geochemistry & Geophysics
Run Chen, Yajun Zhang, Kunpeng Hu, Guanglong Tu, Tianzheng Dou
Summary: The study investigates the impact of supercritical carbon dioxide and water solution on coal, revealing that this treatment can induce migration of elements, changes in pore structure, and an increase in methane adsorption capacity. This research provides significant theoretical support for CO2 sequestration and coalbed methane recovery.
Article
Thermodynamics
Gang Bai, Jun Su, Xueming Li, Chunsheng Guo, Mingxu Han, Xihua Zhou, Chaojun Fan
Summary: The study proposes an SBS-CO2 method that gradually increases the CO2 injection pressure, which can improve the total recovery rate of methane and reduce the risk of CO2 consumption and outburst compared to the traditional constant CO2 injection pressure method.
Article
Energy & Fuels
Yiyu Lu, Jie Liu, Jiren Tang, Xiang Ao, Honglian Li, Jiankun Zhou, Xiao Sun
Summary: The application of liquid CO2-slickwater hybrid fracturing technology can improve the energy-enhancing efficiency and fracturing fluid flowback efficiency of shale reservoirs. However, the retention of supercritical CO2 (ScCO2) fluid and slickwater in reservoirs after fracturing limits the understanding of changes in shale pore structure, which affects the evaluation of gas adsorption, transportation behaviors, and CO2 sequestration capacity in shale reservoirs. Therefore, the influences of ScCO2-slickwater coupling effect on shale pore structure were analyzed using various analytical methods.
Article
Thermodynamics
Zhenzhi Wang, Xuehai Fu, Jienan Pan, Ze Deng
Summary: By conducting experiments on four coal samples with different CH4 saturations, the change of coal strain during N2/CO2-ECBM was studied. The results show that the adsorption swelling rate decreases with increasing saturation, and the order of swelling rate is CO2 > N2 > CH4. The ratio of strain induced by CO2, CH4, and N2 adsorption is approximately 9.52 : 4.05 : 1. During N2-ECBM, the volume shrinkage strain caused by nitrogen injection increases with the increase of methane saturation, and the shrinkage percentage follows the order of medium- > low- > high-rank coal. Replacing injected N2 with CO2 reduces the swelling strain rate compared to CH4 adsorption. In the process of desorption with stepwise depressurization, the strain rate in N2-ECBM follows the order of test 2 < test 3 < test 4, but there is no obvious regularity in CO2-ECBM. The application of CO2-ECBM is more effective in high-rank coal reservoirs. CO2/N2 alternate injection method can improve the injectability of CO2, especially in high-rank coal.
Review
Energy & Fuels
Haiquan An, Zhen Liu, Xinhui Fang, Ziyang Feng, Xuelei Duan
Summary: This study investigated the CO2 gasification kinetics of direct coal liquefaction residue (ER), showing higher reactivity of ER char compared to coal char and an increase in reactivity with higher ER content in blends. The partial pressure of CO2 promoted the reactivity of all samples, and ER char exhibited larger BET surface area and pore volume compared to coal char. Activation energy and reaction order parameters for ER char, coal char, and their blend were also determined.
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
(2021)
Article
Thermodynamics
Xiaolei Wang, Jiabo Geng, Dongming Zhang, Weijing Xiao, Yu Chen, Hao Zhang
Summary: Geological storage of CO2 in coal seams is an effective method to alleviate the greenhouse effect. This study investigated the effects of sub-supercritical CO2 intrusion on coal pore structures and found that CO2 injection leads to changes in porosity and micro-minipore volume. The causes of these changes include mineral dissolution, extraction of functional groups, destruction of aromatic layers, and rearrangement of macromolecular structure. Supercritical CO2 has a greater impact on coal pore structure compared to subcritical CO2. Therefore, it is crucial to choose an appropriate injection and storage pressure of CO2.
Article
Energy & Fuels
Yongbo Yang, Pengchao Xing, Linchao Dai, Xianfeng Liu, Baisheng Nie
Summary: Injection of CO2 into deep unminable coal reservoirs is effective in reducing greenhouse gas emissions. The interaction between supercritical CO2 and coal has an impact on coal structures and strength. This study analyzes the changes in microstructure and mechanical properties of coal induced by supercritical CO2 treatment and supercritical CO2-water saturation, emphasizing the significant influence of water.
Article
Energy & Fuels
Guanglei Zhang, P. G. Ranjith, Xuehai Fu, Xin Li
Summary: The study reveals that lignite has well-developed mesopores and macropores, while fractures are more pronounced in bituminous and anthracite coals. After treatment with ScCO2, lignite showed slight changes in mesopores and macropores, while bituminous and anthracite coals exhibited increased mesopores, macropores, and fractures connectivity. The study suggests that ScCO2 has the potential to increase coal porosity and permeability, providing additional pathways for carbon storage and methane recovery.
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
Engineering, Multidisciplinary
Run Chen, Youyang Wang, Zhiyang Wang
TEHNICKI VJESNIK-TECHNICAL GAZETTE
(2018)
Review
Microbiology
Run Chen, Yunxia Bao, Yajun Zhang
Summary: Biogenic coalbed methane (CBM) is a significant alternative energy source for achieving carbon neutrality. This review summarizes the recent progress in detection technologies and experimental research on biogenic CBM in China. Factors influencing biogenic CBM generation and identification methods are analyzed. Detection technologies for biogas and research methods for microbial diversity are summarized. The review highlights the conditions favoring biogenic CBM production and the three aspects to identify biogenic CBM. The dominant bacterial phyla and archaeal fractions in various basins in China are determined. The review aims to promote the development of coal biotransformation and CO2 bio-utilization to meet energy demands under carbon neutrality.
Review
Geochemistry & Geophysics
Run Chen, Fengrong Lv, Yunxia Bao, Fu Chen, Tianzheng Dou, Guanglong Tu
Summary: The strategic goal of carbon peaking and carbon neutrality has led to the reform of the global energy system. Underground coal gasification is an important method for clean coal development and has advantages of being economical, safe, and environmentally friendly. This paper summarizes the transformation characteristics, evolution of organic matter and minerals, and the transformation of pore structure caused by underground coal gasification.
Article
Geochemistry & Geophysics
Run Chen, Yajun Zhang, Kunpeng Hu, Guanglong Tu, Tianzheng Dou
Summary: The study investigates the impact of supercritical carbon dioxide and water solution on coal, revealing that this treatment can induce migration of elements, changes in pore structure, and an increase in methane adsorption capacity. This research provides significant theoretical support for CO2 sequestration and coalbed methane recovery.
Article
Geosciences, Multidisciplinary
Chen Run, Zhang Pengfei, Qin Yong, Wei Chongtao, Wang Linlin
ACTA GEOLOGICA SINICA-ENGLISH EDITION
(2018)
Article
Geochemistry & Geophysics
Run Chen, Yong Qin, Pengfei Zhang, Youyang Wang