Minerals Impact on CO2 Geo-sequestration in Deep Reservoirs

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Environmental Mineralogy and Biogeochemistry".

Deadline for manuscript submissions: closed (20 January 2022) | Viewed by 13471

Special Issue Editors

School of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China
Interests: rock mechanics; coal seam gas; fluid mechanics; CO2 geo-sequestration; ECBM; mining engineering; permeability; gas diffusion in porous media; cemented past backfill; fly ash
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Guest Editor
School of Mines, China University of Mining and Technology, Xuzhou 221116, China
Interests: multiphysical coupled fields; rock mechanics; CO2 geo-sequestration; liquid nitrogen fracturing; mining engineering; unconventional oil and gas; crack initiation and propagation; permeability

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Guest Editor
School of Civil and Resources Engineering, University of Science and Technology Beijing, Beijing 100083, China
Interests: coal seam gas; CO2 sequestration; coalbed methane; gas diffusion in porous media; coal and gas outburst

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Guest Editor
Department of Earth Science and Engineering, Imperial College London, London SW7 2BP, UK
Interests: pore-scale imaging; multiphase flow; CO2 sequestration; coalbed methane

Special Issue Information

Dear Colleagues,

CO2 geo-sequestration is one potential method to dispose of excess CO2 in the atmosphere. Deeply buried reservoirs such as saline aquifers, unmineable coal seams, tight shale reservoirs, and depleted oil reservoirs are often studied. When CO2 is injected into these reservoirs, it interferes with the initial equilibrium, and chemical interactions occur between the injected CO2 and reservoir rocks, specifically, the minerals in the reservoirs or in the nearby strata (caprock). The dissolution of CO2 into strata brine generates an acidic environment, and the original carbonate minerals, such as quartz, biotite, etc. dissolve into the acid fluid. The concentration of chemical elements Ca, Mg, and K in the brine increases with the injection of CO2. The enhancement of reservoir porosity due to the dissolution of the minerals is dependent on the geochemical properties of the reservoir rocks. Reservoir permeability is improved due to the increase in porosity. On the other hand, the precipitation of these minerals during transportation blocks the fluid migration channels and reduces permeability. Meanwhile, the mechanical properties are also impacted in the in situ stress environment. Rock failure happens if the damages to the mechanical properties accumulate. It is essential to investigate coupled mechanical–chemical transformation for long-term CO2 geo-sequestration in deep reservoirs. 

Dr. Jia Lin
Dr.  Zhaohui Chong
Dr. Gongda Wang
Dr. Guanglei Zhang
Guest Editors

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Keywords

  • CO2 geo-sequestration
  • reservoir porosity
  • permeability
  • coal seam
  • rock mechanics
  • geochemical interactions
  • fluid
  • rock failure
  • hydraulic–mechanical properties

Published Papers (7 papers)

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Research

16 pages, 5233 KiB  
Article
Experimental Study of CO2-ECBM by Injection Liquid CO2
by Mingyang Liu, Hu Wen, Shixing Fan, Zhenping Wang, Jinbiao Fei, Gaoming Wei, Xiaojiao Cheng and Hu Wang
Minerals 2022, 12(3), 297; https://doi.org/10.3390/min12030297 - 26 Feb 2022
Cited by 6 | Viewed by 1876
Abstract
Coal mine gas disasters have severely restricted production safety. Improving gas extraction efficiency can effectively reduce disasters. Scholars have confirmed that CO2 successfully displaces coal seam CH4. This study conducted displacement and in situ experiments and compared gas drainage under [...] Read more.
Coal mine gas disasters have severely restricted production safety. Improving gas extraction efficiency can effectively reduce disasters. Scholars have confirmed that CO2 successfully displaces coal seam CH4. This study conducted displacement and in situ experiments and compared gas drainage under different injection pressures. The displacement experiments indicated that CH4 production rates increased under increased pressures while the displacement ratios decreased. The pressure had a positive effect on sweep efficiency. The in situ experiment showed that CH4 and CO2 concentration trends in the inspection hole remained consistent. Through observing the data of the original and inspection holes, the average gas drainage concentration during low- and medium-pressure injections increased by 0.61 times and 1.17 times, respectively. The low-pressure average gas drainage scalar was increased by 1.08 times. During the medium-pressure injection, the average gas drainage purity increased by 1.94 times. The diffusion ranges of CO2 under low- and medium-pressure injections were 20–25 m and 25–30 m, respectively. The sweep efficiency of medium-pressure injection was 26% better than that of the low-pressure injection, with average pressures of 2.8 MPa and 1.4 MPa, respectively, for sweep efficiency. This study proposes an effective method for improving coal mine gas drainage efficiency. Full article
(This article belongs to the Special Issue Minerals Impact on CO2 Geo-sequestration in Deep Reservoirs)
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18 pages, 7065 KiB  
Article
Numerical Simulation Study on the Multi-Physical Field Response to Underground Coal and Gas Outburst under High Geo-Stress Conditions
by Bo Zhao, Guangcai Wen, Jun Nian, Qianwei Ma, Chaojun Fan, Xiaobo Lv and Chunsheng Deng
Minerals 2022, 12(2), 151; https://doi.org/10.3390/min12020151 - 26 Jan 2022
Cited by 22 | Viewed by 2381
Abstract
Based on thermal–fluid–solid coupling law in coal and gas outburst, a multi-physical field numerical analysis model is built for the whole outburst process. The response laws of stress, gas pressure, temperature, and seepage in different areas and different time nodes around coal and [...] Read more.
Based on thermal–fluid–solid coupling law in coal and gas outburst, a multi-physical field numerical analysis model is built for the whole outburst process. The response laws of stress, gas pressure, temperature, and seepage in different areas and different time nodes around coal and rock mass in the coal and gas outburst under high stress condition are discussed. Research results show: Firstly, the stress response law of the coal and rock mass around the burst hole is initial vibration–sudden attenuation–late stability. Secondly, the gas pressure response law in different areas is that the gas pressure response rate decreases gradually with the increase of the distance from the outburst. Thirdly, the adsorbed gas contained in the broken coal near the outburst port is desorbed rapidly and expands to do work, and the temperature changes dramatically after outburst occurs. In contrast, with the increase of stress, the proportion of elastic potential in total coal and gas outburst energy increases, and the proportion of elastic potential is positively correlated with stress. The critical gas pressure under the energy condition of coal and gas outburst decreases with the increase of stress. It illustrates that the lower gas pressure can also meet the energy condition of coal and gas outburst under high stress. Full article
(This article belongs to the Special Issue Minerals Impact on CO2 Geo-sequestration in Deep Reservoirs)
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13 pages, 14438 KiB  
Article
An Experimental Investigation of the Gas Permeability of Tectonic Coal Mineral under Triaxial Loading Conditions
by Zhaoying Chen, Guofu Li, Yi Wang, Zemin Li, Mingbo Chi, Hongwei Zhang, Qingling Tian and Junhui Wang
Minerals 2022, 12(1), 70; https://doi.org/10.3390/min12010070 - 05 Jan 2022
Cited by 5 | Viewed by 1271
Abstract
Underground coal mining of CH4 gas-rich tectonic coal seams often induces methane outburst disasters. Investigating gas permeability evolution in pores of the tectonic coal is vital to understanding the mechanism of gas outburst disasters. In this study, the triaxial loading–unloading stresses induced [...] Read more.
Underground coal mining of CH4 gas-rich tectonic coal seams often induces methane outburst disasters. Investigating gas permeability evolution in pores of the tectonic coal is vital to understanding the mechanism of gas outburst disasters. In this study, the triaxial loading–unloading stresses induced gas permeability evolutions in the briquette tectonic coal samples, which were studied by employing the triaxial-loading–gas-seepage test system. Specifically, effects of loading paths and initial gas pressures on the gas permeability of coal samples were analyzed. The results showed the following: (1) The gas permeability evolution of coal samples was correlated with the volumetric strain change during triaxial compression scenarios. In the initial compaction and elastic deformation stages, pores and cracks in the coal were compacted, resulting in a reduction in gas permeability in the coal body. However, after the yield stage, the gas permeability could be enhanced due to sample failure. (2) The gas permeability of the tectonic coal decreased as a negative exponential function with the increase in initial gas pressure, in which the permeability was decreased by 67.32% as the initial gas pressure increased from 0.3 MPa to 1.5 MPa. (3) Coal samples underwent a period of strain development before they began to fail during confining pressure releasing. After the stress releasing-induced yield stage, the coal sample was deformed and cracked, resulting in a quickly increase in gas permeability. With a further releasing process, failure of the sample occurred, and thus induced rapidly increasing gas permeability. These obtained results could provide foundations for gas outburst prevention in mining gas-rich tectonic coal seams. Full article
(This article belongs to the Special Issue Minerals Impact on CO2 Geo-sequestration in Deep Reservoirs)
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21 pages, 3071 KiB  
Article
Gas Migration Patterns with Different Borehole Sizes in Underground Coal Seams: Numerical Simulations and Field Observations
by Haibo Liu, Zhihang Shu, Yinbin Shi, Xuebing Wang, Xucheng Xiao and Jia Lin
Minerals 2021, 11(11), 1254; https://doi.org/10.3390/min11111254 - 11 Nov 2021
Cited by 1 | Viewed by 1702
Abstract
Gas flow in a coal seam is a complex process due to the complicated coal structure and the sorption characteristics of coal to adsorbable gas (such as carbon dioxide and methane). It is essential to understand the gas migration patterns for different fields [...] Read more.
Gas flow in a coal seam is a complex process due to the complicated coal structure and the sorption characteristics of coal to adsorbable gas (such as carbon dioxide and methane). It is essential to understand the gas migration patterns for different fields of engineering, such as CBM exploitation, underground coal mine gas drainage, and CO2 geo-sequestration. Many factors influence gas migration patterns. From the surface production wells, the in-seam patterns of gas content cannot be quantified, and it is difficult to predict the total gas production time. In order to understand the gas flow patterns during gas recovery and the gas content variations with respect to production time, a solid-fluid coupled gas migration model is proposed to illustrate the gas flow in a coal seam. Field data was collected and simulation parameters were obtained. Based on this model, different scenarios with different borehole sizes were simulated for both directional boreholes and normal parallel boreholes in coal seams. Specifically, the borehole sizes for the directional boreholes were 10 m, 15 m, and 20 m. The borehole sizes for the normal parallel boreholes were 2 m, 4 m, and 6 m. Under different gas drainage leading times, the total gas recovery and residual gas contents were quantified. In Longwall Panel 909 of the Wuhushan coal mine, one gas drainage borehole and five 4 m monitoring boreholes were drilled. After six months of monitoring, the residual gas content was obtained and compared with the simulation results. Of the total gas, 61.36% was drained out from the first 4 m borehole. In this field study, the effective drainage diameter of the drainage borehole was less than 8 m after six months of drainage. The gas drainage performance was tightly affected by the borehole size and the gas drainage time. It was determined that the field observations were in line with the simulation results. The findings of this study can provide field data for similar conditions. Full article
(This article belongs to the Special Issue Minerals Impact on CO2 Geo-sequestration in Deep Reservoirs)
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14 pages, 6414 KiB  
Article
Laboratory Study of Deformational Characteristics and Acoustic Emission Properties of Coal with Different Strengths under Uniaxial Compression
by Shuangwen Ma, Han Liang and Chen Cao
Minerals 2021, 11(10), 1070; https://doi.org/10.3390/min11101070 - 29 Sep 2021
Cited by 4 | Viewed by 1593
Abstract
Acoustic emission (AE) can reflect the dynamic changes in a material’s structure, and it has been widely used in studies regarding coal mechanics, such as those focusing on the influence of loading rate or water content change on the mechanical properties of coal. [...] Read more.
Acoustic emission (AE) can reflect the dynamic changes in a material’s structure, and it has been widely used in studies regarding coal mechanics, such as those focusing on the influence of loading rate or water content change on the mechanical properties of coal. However, the deformational behavior of coals with various strengths differs due to the variation in microstructure. Hard coal presents brittleness, which is closely related to certain kinds of geological disasters such as coal bursts; soft coal exhibits soft rock properties and large deformation mechanical characteristics. Therefore, conclusions drawn from AE characteristics of a single coal sample have application limitations. This paper studies the deformation patterns and AE characteristics of coals with different strengths. A uniaxial compression experiment was carried out using coal samples with average uniaxial compressive strengths of 30 MPa and 10 MPa; the SAEU2S digital AE system was used to measure the AE counts, dissipation energy, and fracturing point distributions at each deformation stage of the different coals. The results show that the bearing capacity of hard coal is similar to that of the elastic stage and plastic deformation stage, but it may lose its bearing capacity immediately after failure. Soft coal has a relatively distinct stress-softening deformation stage and retains a certain bearing capacity after the peak. The AE counts and dissipation energy of hard coal are significantly higher than those of soft media, with average increases of 49% and 26%, respectively. Via comparative analysis of the distribution and development of internal rupture points within soft coal and hard coal at 15%, 70%, and 80% peak loads, it was observed that hard coal has fewer rupture points in the elastic deformation stage, allowing it to maintain good integrity; however, its rupture points increase rapidly under high stress. Soft coal produces more plastic deformation under low loading conditions, but the development of the fracture is relatively slow in the stress-softening stage. We extracted and summarized the AE characteristics discussed in the literature using one single coal sample, and the results support the conclusions presented in this paper. This study subdivided the deformation process and AE characteristics of soft and hard coals, providing a theoretical guidance and technical support for the application of AE technology in coal with different strengths. Full article
(This article belongs to the Special Issue Minerals Impact on CO2 Geo-sequestration in Deep Reservoirs)
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18 pages, 4727 KiB  
Article
Dynamic Response Mechanism of Impact Instability Induced by Dynamic Load Disturbance to Surrounding Rock in High Static Loading Roadway
by Jiazhuo Li, Penghui Guo, Heng Cui, Shikang Song, Wentao Zhao, Jiaqi Chu and Wenhao Xie
Minerals 2021, 11(9), 971; https://doi.org/10.3390/min11090971 - 06 Sep 2021
Cited by 12 | Viewed by 1862
Abstract
Deep high static loading roadway is extremely prone to rock burst under dynamic load disturbance. The “force-energy criterion” for the failure of surrounding rock in such deep roadways and the “energy criterion” for the rock burst was established by considering the stress and [...] Read more.
Deep high static loading roadway is extremely prone to rock burst under dynamic load disturbance. The “force-energy criterion” for the failure of surrounding rock in such deep roadways and the “energy criterion” for the rock burst was established by considering the stress and energy evolution characteristics of rock burst under this circumstance. Under the engineering background of the main roadway in No.1 mining area of Gaojiapu Coal Mine in Binchang Mining Area, Shaanxi Province, China, the partial stress field and distortion energy field of surrounding rock in the main roadway and the spatial-temporal evolution laws under dynamic load disturbance were simulated and analyzed by using a built-in dynamic module of FLAC3D. Results show that after the dynamic load disturbance, the partial stress and distortion energy are concentrated in the shallow part at two walls of the roadway in the early phase. With the continuous propagation of dynamic load stress wave, the partial stress and distortion energy are transferred to the deep part. The sudden high-energy release occurred in the peak zone of partial stress, leading to the plastic failure of coal and rock mass. Subsequently, the distortion energy was fully accumulated in the original plastic zone and transferred from shallow surrounding rocks to the deep surrounding rocks in the roadway, where the partial stress and distortion energy of coal and rock mass reached the yield conditions. Thus, the original plastic zone was sharply expanded, thereby forming a new plastic zone. The coal and rock mass experienced an approximately static failure when no residual energy (ΔU) was found in it. When ΔU > 0, the rock mass experienced dynamic failure, and ΔU was mainly the volume transformation energy, which is approximately one-half of the total elastic strain energy. ΔU was transformed into the initial kinetic energy of broken coal and rock mass. Thus, the coal and rock mass are burst out. In severe cases, this condition was manifested by the rock burst in the main roadway. An optimization scheme of prevention and control measures for rock burst was proposed on the basis of the above conclusions. The microseismic activity laws before and after the unloading were compared, and a good effect was achieved. The research results can lay a theoretical foundation for predicting and preventing rock bursts in coal mines by actively regulating the disaster-pregnant environment and mitigating the disaster-inducing conditions. Full article
(This article belongs to the Special Issue Minerals Impact on CO2 Geo-sequestration in Deep Reservoirs)
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13 pages, 2934 KiB  
Article
Experimental Study on Relative Permeability Characteristics for CO2 in Sandstone under High Temperature and Overburden Pressure
by Ke Ding, Lianguo Wang, Bo Ren, Zhaolin Li, Shuai Wang and Chongyang Jiang
Minerals 2021, 11(9), 956; https://doi.org/10.3390/min11090956 - 31 Aug 2021
Cited by 8 | Viewed by 1614
Abstract
In this study, CO2 seepage of sandstone samples from the Taiyuan-Shanxi Formation coal seam roof in Ordos Basin, China, under temperature-stress coupling was studied with the aid of the TAWD-2000 coal rock mechanics-seepage test system. Furthermore, the evolution law and influencing factors [...] Read more.
In this study, CO2 seepage of sandstone samples from the Taiyuan-Shanxi Formation coal seam roof in Ordos Basin, China, under temperature-stress coupling was studied with the aid of the TAWD-2000 coal rock mechanics-seepage test system. Furthermore, the evolution law and influencing factors on permeability for CO2 in sandstone samples with temperature and axial pressure were systematically analyzed. The results disclose that the permeability of sandstone decreases with the increase in stress. The lower the stress is, the more sensitive the permeability is to stress variation. High stress results in a decrease in permeability, and when the sample is about to fail, the permeability surges. The permeability of sandstone falls first and then rises with the rise of temperature, which is caused by the coupling among the thermal expansion of sandstone, the desorption of CO2, and the evaporation of residual water in fractures. Finally, a quadratic function mathematical model with a fitting degree of 98.2% was constructed between the temperature-stress coupling effect and the permeability for CO2 in sandstone. The model provides necessary data support for subsequent numerical calculation and practical engineering application. The experimental study on the permeability characteristics for CO2 in sandstone under high temperature and overburden pressure is crucial for evaluating the storage potential and predicting the CO2 migration evolution in underground coal gasification coupling CO2 storage projects. Full article
(This article belongs to the Special Issue Minerals Impact on CO2 Geo-sequestration in Deep Reservoirs)
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