Experimental study on the softening effect and mechanism of anthracite with CO2 injection

Cao, Liwen; Sang, Shuxun; Wang, Wei; Zhou, Xiaozhi; Yuan, Wei; Ji, Zhongmin; Chang, Jiangfang; Li, Mengyang

doi:10.1016/j.ijrmms.2021.104614

Cited by 48 publications

(20 citation statements)

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“…In addition, it has been reported that carbon capture and sequestration technology can effectively reduce the CO 2 content in the atmosphere . By injecting CO 2 into deep unmineable coal seams, the geological sequestration of CO 2 and effective development of CBM can be achieved, which have environmental and energy benefits. , Pores are an important part of the coal matrix, as well as the main storage space and migration channels for gas in coal; their development directly affects the adsorption/desorption, diffusion, and seepage of gas , and thus the development of CBM and CO 2 sequestration. Different pore structure development characteristics correspond to the specific coal-forming environment and coal metamorphic degree.…”

Section: Introductionmentioning

confidence: 99%

Coal Pores: Methods, Types, and Characteristics

et al. 2021

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Coal pores are the locations of coalbed methane occurrence and enrichment and the main storage space targeted in CO2 sequestration. The systematic investigation of the coal pore structure and its development is of great significance to provide insights into coalbed methane generation, coal mine gas outburst mechanisms, and coal seam CO2 sequestration. In this study, coal pore testing technologies and methods, pore classification methods, and coal pore structure characteristics and their main control factors were systematically investigated and summarized. The results show that direct test methods, indirect fluid injection test methods, and X-ray and spectroscopic methods have been used for the quantitative characterization of the pore structure. However, each testing method has limitations. Therefore, a comprehensive method for the quantitative characterization of the full-scale pore structure must be developed, especially for the accurate quantitative characterization of closed pores in coal. The in situ measurement of pores in coal is one of the future research trends. Classification methods of pores in coal mainly include the classification of the genetic pore type, pore size, and pore morphology. Metamorphism, tectonic deformation, and macerals are the main internal factors affecting the pore distribution in coal. The effect of tectonic deformation on the macromolecular structure and micro- and ultramicropores of coal must be further studied. In addition, molecular mechanics simulations, molecular dynamics simulations, and quantum chemistry calculations of the dynamic response of the macromolecular structure and micro- and ultramicropores during gas adsorption and desorption must be carried out.

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Section: Introductionmentioning

confidence: 99%

Coal Pores: Methods, Types, and Characteristics

et al. 2021

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“…It is generally known that the influencing factors of CBM recovery are various and interactive. Based on the previous investigations (Fu et al, 2016; Niu et al, 2021a; Peng et al, 2017), factors that control the CBM potential are divided into five main factors and seventeen sub-main factors as follows: Coal maceral composition and quality: gas content, moisture ( M ad ), ash yield ( A ad ), volatile matter ( V ad ), fixed carbon ( C ad ); Coalification: R o , max , vitrinite, inertinite, mineral; Pore structure: BET pore specific surface area, BET pore volume, BET pore diameter; Coal reservoir condition: reservoir pressure, temperature; Geological and hydrogeological conditions: total dissolved solids (TDS), the fractal dimension of fault, buried depth of coal seam. …”

Section: Resultsmentioning

confidence: 99%

Section: Influencing Factors and Their Spatial Distribution In South ...mentioning

confidence: 99%

Evaluation of deep high-rank coal seam gas content and favorable area division based on GIS: A case study of the South Yanchuan block in Ordos Basin

Cao

Cui³

et al. 2022

Energy Exploration & Exploitation

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The South Yanchuan block is the deepest developed high-rank coalbed methane (CBM) field in China, the geological conditions in this block are complex and the main controlling factors of CBM content are various. Thus, a decision-making model of the potential of deep high-rank coalbed methane resource based on geographical information system (GIS) and weighted linear combination (WLC) is established, the influence of geological conditions on CBM content is analyzed, the favorable areas of CBM potential are divided. Results show that the buried depth, coal rank and hydrodynamic condition in the coal seam are dominant factors that control the gas content on a block scale, while the gas content has a weak correlation with maceral composition, coal thickness and the effective thickness of the overlying strata. The study area is divided into five units according to the natural breaks method, i.e., the extramely favourable area, the favourable area, the relatively favourable area, the normally favourable area and the unfavourable area, which account for 14.23%, 22.23%, 24.77%, 25.08% and 13.70% in area, respectively. The extramely favourable area is located in the northwestern of the South Yanchuan block, which is considered to be the key exploration and development area. The study will deepen the understanding of the control of CBM potential in south Yanchuan Block, and is of practical significance for CBM recovery in this area.

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“…However, the gas leak is largely dependent on the characteristics of overlying strata, especially for its mineral composition, integrality, and mechanical properties. For example, the PV and SSA changes induced by the ScCO 2 –water–rock reaction indicate that the primary pores are promoted or new pore fractures are formed; the two ways cause both the stress concentration and the increase of rock compressibility, leading to the attenuation of mechanical strength and the damage of rock stratum under the high ground stress condition . Therefore, more studies are expected about the effect of the ScCO 2 –water–rock reaction on physical and geomechanics properties of different caprocks in target areas, which are equally important for the successful and secure implementation of CO 2 -ECBM projects.…”

Section: Resultsmentioning

confidence: 99%

Changes of Multiscale Surface Morphology and Pore Structure of Mudstone Associated with Supercritical CO₂-Water Exposure at Different Times

et al. 2021

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CO2 enhanced coalbed methane recovery (CO2-ECBM) has been confirmed as an effective technology to improve coalbed methane (CBM) production; however, the injected CO2 and the reservoir water can react with the caprock of the coal seam, which changes its internal structure and increases the risk of CO2 leakage. To clarify the CO2–water–rock reaction process and the structural responses of the caprock, the roof mudstone samples of coal seams from Qinshui Basin were first selected to conduct the geochemical reaction experiment; then, scanning electron microscopy (SEM), N2 adsorption, and mercury intrusion porosimetry were adopted to monitor the multiscale structure alteration of the samples. The results show that the rock sample has progressively deteriorated during the CO2–water–rock reaction process, and this effect is aggravated with the increase of the reaction time. The dissolution process consists of three stages: (1) lots of isolated and shallow holes are developed; (2) holes are connected and formed to the dissolution grooves; (3) dissolution grooves are widened, and the dissolution zone is expanded until all the soluble minerals immerse into the reaction solution. The pore volume (PV) and specific surface area (SSA) of small pores are reduced, while those of large pores are increased, which can be attributed to the pore-blocking effect caused by clay mineral swelling and mineral precipitation and the pore-enlarging effect caused by mineral dissolution, respectively. Additionally, the ScCO2–water–rock reaction varies the pore structure distribution and makes the PV distribution more heterogeneous and the SSA distribution more homogeneous. The changes in the internal structure of the roof mudstone promote gas diffusion and seepage, which may increase the potential threat of CO2 leakage during the long-term CO2-ECBM process to a certain degree. This study will provide an essential basis for the investigation and evaluation of the security of CO2-ECBM in Qinshui Basin, China.

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Experimental study on the softening effect and mechanism of anthracite with CO2 injection

Cited by 48 publications

References 58 publications

Coal Pores: Methods, Types, and Characteristics

Coal Pores: Methods, Types, and Characteristics

Evaluation of deep high-rank coal seam gas content and favorable area division based on GIS: A case study of the South Yanchuan block in Ordos Basin

Changes of Multiscale Surface Morphology and Pore Structure of Mudstone Associated with Supercritical CO₂-Water Exposure at Different Times

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Experimental study on the softening effect and mechanism of anthracite with CO2 injection

Cited by 48 publications

References 58 publications

Coal Pores: Methods, Types, and Characteristics

Coal Pores: Methods, Types, and Characteristics

Evaluation of deep high-rank coal seam gas content and favorable area division based on GIS: A case study of the South Yanchuan block in Ordos Basin

Changes of Multiscale Surface Morphology and Pore Structure of Mudstone Associated with Supercritical CO2-Water Exposure at Different Times

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Changes of Multiscale Surface Morphology and Pore Structure of Mudstone Associated with Supercritical CO₂-Water Exposure at Different Times