Article
Energy & Fuels
Guanglei Zhang, P. G. Ranjith, Zhongsheng Li, Mingzhong Gao, Zhaoyang Ma
Summary: In this study, the long-term effects of CO2 injection on the structural and mechanical properties of water-saturated coal were investigated. It was found that the presence of water during CO2 injection resulted in significant changes in the mechanical properties of coal, primarily due to sorption-induced cracking causing structural damage. The extent of reduction in mechanical properties was less compared to pure CO2 injection, potentially due to the hindrance of CO2 sorption by water.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
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
Energy & Fuels
Xianfeng Liu, Chaolin Zhang, Baisheng Nie, Chengpeng Zhang, Dazhao Song, Tao Yang, Zhengtao Ma
Summary: Injection of CO2 into coal seams is a critical method for enhanced coalbed methane recovery and carbon sequestration. This study investigates the influence of supercritical CO2 saturation time on the mechanical properties and structural changes of coal. The results show that after interaction with supercritical CO2, the mechanical properties of coal are significantly altered, with reductions in compressive strength, elasticity modulus, and tensile strength. These changes are time-dependent and primarily occur within 9 days of saturation. Additionally, the porosity and pore specific surface area of coal increase with interaction time.
Article
Energy & Fuels
Sivachidambaram Sadasivam, Shakil Masum, Min Chen, Kamil Stanczyk, Hywel Thomas
Summary: This study explores the CO2 adsorption-desorption kinetics of bituminous coal under low pressure injection and compares different models to fit the data. The results suggest that bulk pore diffusion, surface interaction, and multilayer adsorption are the rate-determining steps.
Article
Thermodynamics
Yunzhuo Li, Huaijun Ji, Guichuan Li, Shaobin Hu, Xu Liu
Summary: This study investigates the impact of carbon dioxide phase change fracturing on the microstructure of coal and finds that this process disrupts hydrogen bonds within coal, reducing the cross-linking density of the coal structure. Additionally, it breaks fatty alkyl side chains and oxygen-containing functional groups, causing side chains to detach and fatty chains to shorten. Furthermore, the fracturing decreases the interlayer spacing of aromatic layers, increases the aromaticity of coal, enlarges the volume and basic unit structure of coal crystal nucleus, and increases the flattening degree.
Article
Thermodynamics
Erlei Su, Yunpei Liang, Xiangjun Chen, Zhaofeng Wang, Xiaoming Ni, Quanle Zou, Haidong Chen, Jiaqi Wei
Summary: This study investigated the pore structure and mechanical properties of coal samples after CO2 treatment using low-field nuclear magnetic resonance tests and uniaxial compression tests. The results provide insights into the mechanism of how pore structure influences the mechanical properties and have implications for long-term safety assessment and injection pressure selection in CO2 sequestration.
Article
Energy & Fuels
Maram Almolliyeh, Sivachidambaram Sadasivam, Min Chen, Shakil Masum, Hywel Rhys Thomas
Summary: This paper presents the experimental design and results of CO2-CH4 core flooding and permeability studies conducted with large intact coal core samples. The study found that the size of the core samples has an impact on the permeability measurements, and CO2 injection resulted in decreased CO2 permeability and increased CH4 permeability, indicating CO2 adsorption and CH4 displacement.
INTERNATIONAL JOURNAL OF COAL GEOLOGY
(2023)
Article
Energy & Fuels
Oluwafemi John Omotilewa, Palash Panja, Carlos Vega-Ortiz, John McLennan
Summary: The study explored the CO2 storage capacity and CO2-ECBM recovery potential in Uinta Basin's Buzzard Bench area, finding that injecting 1.16 million tons of CO2 and sequestering 1.15 million tons over 20 years is feasible, with 13.95 billion cubic feet of methane recovered within the same period. Despite a 19% decrease in methane recovery due to permeability reduction by coal matrix swelling, the results demonstrated the feasibility of injection and production in the presence of potential permeability changes during CO2 injection.
JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING
(2021)
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
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
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
Chemistry, Physical
Sang-Rak Sim, Dong-Woo Ryu
Summary: To prevent drastic climate change, it is necessary to reduce greenhouse gas emissions in all industrial sectors. This study focuses on measures to reduce greenhouse gas emissions in the cement industry, using a carbon utilization fixation technology that utilizes concrete slurry water. The results showed promising carbonation reactions, but further research is needed to identify reaction products in the supernatant water.
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.
Article
Geosciences, Multidisciplinary
Jinfeng Liu, Christopher J. Spiers
Summary: The permeability evolution in coal reservoirs during CO2-enhanced coalbed methane (ECBM) production is greatly affected by the swelling/shrinkage effects caused by the sorption and desorption of CO2 and CH4. The study shows that the permeability of methane and CO2 is influenced by the coupled effects of self-stress, change in effective stress coefficient, sorption-induced closure of transport paths, and heterogeneous gas penetration and equilibration dependent on diffusion.
FRONTIERS IN EARTH SCIENCE
(2022)
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
Jizhao Xu, Cheng Zhai, Pathegama Gamage Ranjith, Shuxun Sang, Yong Sun, Yuzhou Cong, Wei Tang, Yangfeng Zheng
Summary: The study investigated the effects of liquid CO2 on coal strength, finding that the coupled effects of liquid CO2 temperature and adsorption can influence coal fracture behavior and crack morphology.
Article
Energy & Fuels
Jizhao Xu, Cheng Zhai, P. G. Ranjith, Shuxun Sang, Xu Yu, Yong Sun, Yuzhou Cong, Yangfeng Zheng, Wei Tang
Summary: The study found that coal affected by liquid CO2 exhibited more complex destruction patterns, larger fractal dimensions, and greater structure degradation. The affected coals showed diverse mechanical responses, with temperature shock and CO2 adsorption potentially leading to crack growth and strength deterioration, ultimately destroying the coal with smaller yield strength.
Article
Energy & Fuels
David Lall, Vikram Vishal, M. V. Lall, P. G. Ranjith
Summary: The study found that gas production was less efficient in the presence of a permeable heterogeneity compared to other scenarios. The permeability affects the vertical extent of dissolved methane volume during thermal stimulation and huff and puff, while well depth influences the radial extent of dissociated molecules.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Engineering, Geological
Chunlin Zhong, Zhenyu Zhang, P. G. Ranjith, Chengpeng Zhang, Kangsheng Xue
Summary: The study found that pore water can affect the radial and volumetric strain evolution of coal, leading to dilation deformation. Additionally, due to the water propping effect, the cracks in saturated coal cannot close tightly during loading, causing sliding and generating numerous tensile cracks. Loading frequency can impact the decay of pore pressure, consequently influencing the number of cracks in coal.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Energy & Fuels
Shashika Gajanayake, Ranjith Pathegama Gamage, Pabasara Wanniarachchige, Decheng Zhang
Summary: This study conducted molecular dynamic simulations to investigate the effects of temperature, pressure, and initial CO2 concentration on gas replacement characteristics for methane recovery and CO2 storage. The results showed that higher temperatures resulted in greater methane recovery, but diminished CO2 storage capacity. Higher initial CO2 concentrations facilitated better CO2 penetration into the hydrate structure, leading to increased methane recovery and improved CO2 storage.
JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING
(2022)
Article
Thermodynamics
P. Cheng, C. P. Zhang, Z. Y. Ma, J. P. Zhou, D. C. Zhang, X. F. Liu, H. Chen, P. G. Ranjith
Summary: Nanoindentation tests were conducted to investigate the effects of ScCO2-water treatment on shale matrix micromechanics, revealing significant heterogeneity in the properties of different minerals. Observation of indentation morphologies showed that considerable micro-fractures were generated in clay minerals, correlated to significant plastic deformation and layered crystal structures.
Article
Energy & Fuels
Decheng Zhang, Hao Tang, Xiaogang Zhang, P. G. Ranjith, M. S. A. Perera
Summary: This study investigates the effects of roughness, slit width, and pressure on methane adsorption characteristics by constructing nanoscale slits using graphene instead of shale. The results show that the adsorption configurations depend on the slit width and surface roughness. Rough slits have discontinuous adsorption layers, and weak second adsorption layers form in large slits under high pressures. The inaccessible volume increases with roughness, leading to a reduction in accessible volume. Excess and absolute adsorption decrease with roughness but increase with slit width at the microscopic scale. The Langmuir-Freundlich model fits well with excess adsorption isotherms. Adsorption is found to be more stable in smaller and rougher slits due to the superposition of adsorption potentials.
JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING
(2022)
Article
Engineering, Geological
K. M. A. S. Bandara, P. G. Ranjith, W. Zheng, D. D. Tannant, V. R. S. De Silva, T. D. Rathnaweera
Summary: This study provides a grain-scale analysis of the fracture evolution mechanisms of proppant crushing, rock fracture damage during proppant embedment, and the influence of realistic reservoir/fracture fluid on proppant embedment. The results reveal that the selection of an appropriate proppant type is vital in quantifying the degree of proppant crushing and embedment within fractures.
Article
Thermodynamics
Guanglei Zhang, P. G. Ranjith, Qiao Lyu
Summary: This study reveals the effects of CO2 on the micro and nano-scale properties of coal, confirms the softening effects of CO2 on coal, and indicates that these changes are reversible to some extent.
Article
Energy & Fuels
B. Balinee, P. G. Ranjith, Herbert E. Huppert
Summary: The article discusses the impact of building material production on global carbon emissions and presents methods to reduce environmental impact through the use of waste and carbon sequestration. By incorporating discarded aluminum foil and industrial waste gases into cement, the performance and sustainability of cement can be improved. This approach significantly reduces carbon emissions, lowers costs, and stores a large amount of CO2.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2022)
Article
Thermodynamics
Xiaogang Zhang, Chao Jin, Decheng Zhang, Chengpeng Zhang, P. G. Ranjith, Yong Yuan
Summary: In this study, experimental tests were conducted on macro-scale reconstituted high rank coal samples to investigate the flow behavior of CO2. The results showed that the permeability of CO2 decreases with injection pressure and depth, and the reduction is more significant at higher injection pressures. Higher CO2 injection pressure results in greater pressure development and a smaller effective zone of influence. Furthermore, CO2 storage capacity decreases with depth, while the ultimate storage capacity increases with CO2 injection pressure for each injection.
Article
Engineering, Geological
V. R. S. De Silva, H. Konietzky, H. Mearten, P. G. Ranjith, W. G. P. Kumari
Summary: This study proposes a novel approach called the hybrid rock pre-conditioning method to enhance the sustainability and efficiency of low-grade ore mining. The method involves the use of soundless cracking demolition agents (SCDAs) to initiate radial fractures in a predrilled host rock, followed by hydraulic stimulation to extend the fractures. The results show that this method can create a high density of fractures around the injection well, and key factors such as rock mass heterogeneity and stress anisotropy affect its performance.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Review
Energy & Fuels
H. B. S. Sathsarani, K. H. S. M. Sampath, A. S. Ranathunga
Summary: Global warming is a pressing issue caused by increased greenhouse gas emissions, particularly CO2. Ordinary Portland Cement (OPC) has shown shortcomings as cement material in CO2 sequestration, leading to the introduction of fly ash (FA)-based geopolymers as a replacement. This study provides a comparative review between OPC and FA-based geopolymers, analyzing their behavior and properties in the context of CO2 sequestration.
GAS SCIENCE AND ENGINEERING
(2023)
Article
Energy & Fuels
M. H. Samarakoon, P. G. Ranjith
Summary: Ensuring the intactness of cement sheaths is crucial for deep well applications in extreme underground conditions. This study investigates the behavior of wellbore materials, including steel casing, annulus cement sheaths, and surrounding rock formations, under continuous steam injection. The results show that materials in carbonate formations are more vulnerable to stress than those in sandstone formations, and the retention time of maximum temperature in cement sheaths is shorter in sandstone than in carbonate. It is also found that the cement sheaths in compliant formations like sandstone may fail due to tensile cracking along the thinnest thickness.
GEOENERGY SCIENCE AND ENGINEERING
(2023)
Article
Engineering, Chemical
Huping Wang, Zhao Wang, Sanqing Ding, Chao Jin, Xiaogang Zhang, Langtao Liu
Summary: This study investigates the effect of stress conditions on the mechanical properties of coal during CO2 sequestration. The results show that coal strength increases with increasing confining pressure, but this effect diminishes with higher confining pressures. The critical confining pressure is determined to be approximately 20 MPa, at which all samples exhibit similar failure strength. The application of high-pressure super-critical CO2 can strengthen the coal.