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Characterization of pore structures and flow simulation are essential to spatial migration of coalbed methane. In this paper, coal samples from Xinjing and Xinzhuang coal mines are collected and a comprehensive characterization method by using computed tomography (CT) technique and experiments of mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) is proposed. Pore structure parameters are finely characterized and analyzed. Moreover, the flow process for coal samples is visualized and flow characteristics are analyzed. The result shows that pore structures of coal samples are strongly heterogeneous and are dominated by micropores, and filled with kaolinite, calcium monofluorophosphate, pyrite, etc. The flow velocity increases obviously in micropores and narrow throats. The flow is greatly affected by the pore structure. This study is of practical significance for the coalbed methane recoverability evaluation and exploration. [ABSTRACT FROM AUTHOR]

Geological sequestration of carbon dioxide (CO2) is an effective method to reduce greenhouse gases and an important technology for carbon neutralization. Among all geological sequestration sites, coal reservoirs are potentially effective and practicable. The Xiangzhong Depression of Hunan Province of China is selected as the research area, and the coal seam of Longtan Formation is the target reservoir in this paper. CO2‐enhanced coalbed methane (CO2‐ECBM) and CO2 sequestration capacity are both simulated according to the laboratory experiments on reservoir parameters. During simulation, four production wells and one injection well were designed, and the simulation process can be divided into two stages: CO2‐ECBM and CO2 geological storage. The CO2‐ECBM stage refers to CO2 injection for increasing methane production, and the CO2 geological storage stage aims to predict the CO2 sequestration capacity. After that, sensitivity analyses of sequestration effect are carried out. During the simulation, when maintaining a constant pressure injection of CO2 under the original conditions of 0.01 mD permeability, 9% porosity, and 1.47 MPa reservoir methane pressure, the total storage amount is only 0.14 × 106 m3. However, the storage amount increases significantly to 6.62 × 106 m3 if the permeability increases to 1.5 mD. Orthogonal simulation indicates that permeability has the greatest impact on CO2 sequestration. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Migration abilities of conventional quartz sand and ceramsite proppant are compared. Results show that area of sand dike and suspended sand for quartz sand is both smaller than that of ceramsite, and the width generation capacity of quartz sand is weaker than that of ceramsite. Then, a typical coalbed mehane well named QS01 well located at Gaohe block of Qinshui Basin is selected as the simulation object, and physical experiments and mathematical simulations are both conducted to obtain the migration feature of ceramsite proppant and its granularity matching. Results show that under the same closure pressure, the fracture conductivity of bigger size is greater than that of smaller size; for bigger size ceramsite, the decrease rate will be reduced as closure pressure increasing, which indicates that the bigger size ceramsite has been effectively supported under bigger closure pressure. If the granularity matching of 250-380 μm, 380-1 000 μm and 830-1 400 μm is 1∶6∶2, the proppant concentration is the biggest, and the fracture conductivity is the strongest. If the granularity matching is 3∶1∶2, the proppant concentration is the smallest, and the fracture conductivity is the weakest. And if the granularity matching is 1∶1∶1, the values of proppant concentration and fracture conductivity are among the values of the two conditions above. As a result, the granularity matching should set as 1∶6∶2 during fracturing.

The present study investigated the effects of Fe/SiO2 and MgO content on the viscous behaviors of the slag formed by the charging of secondary resources into the copper-smelting furnace. It is determined that the increase of Fe/SiO2 (0.8–1.2) and the addition of MgO (1–7 wt pct) both reduce the slag viscosity. The addition of MgO accelerates the transition of breaking temperature of slags to higher temperatures, while the effect of Fe/SiO2 on that is relatively complicated. Fourier transform infrared spectroscopy (FTIR) and Raman spectra indicate that increases in either Fe/SiO2 or MgO content contribute to depolymerization of silicate network structures in high-temperature melts. The [AlO6]9− octahedra in the melt tended to increase with increasing Fe/SiO2 and MgO content, while the opposite change is observed for [FeO4]5− tetrahedra. Moreover, an increase in Fe/SiO2 or MgO content also leads to a gradual decrease in the activation energy of slag viscous flow, except in the case of Fe/SiO2 of 1.2 and MgO content of 7 wt pct. This unexpected discrepancy can be accounted for different types of flow units that arise in the slag at high temperatures. [ABSTRACT FROM AUTHOR]

Abstract: The uranium deposits in the Tuanyushan area of northern Qaidam Basin commonly occur in coal‐bearing series. To decipher the U‐enrichment mechanism and controlling factors in this area, a database of 72 drill cores, including 56 well‐logs and 3 sampling wells, was examined for sedimentology and geochemistry in relation to uranium concentrations. The results show that coal‐bearing series can influence uranium mineralization from two aspects, i.e., spatial distribution and dynamic control. Five types of uranium‐bearing rocks are recognized, mainly occurring in the braided river and braided delta sedimentary facies, among which sandstones near the coals are the most important. The lithological associations of sandstone‐type uranium deposits can be classified into three subtypes, termed as U‐coal type, coal‐U‐coal type, and coal‐U type, respectively. The coal and fine siliciclastic rocks in the coal‐bearing series confined the U‐rich fluid flow and uranium accumulation in the sandstone near them. Thus, the coal‐bearing series can provide good accommodations for uranium mineralization. Coals and organic matters in the coal‐bearing series may have served as reducing agents and absorbing barriers. Methane is deemed to be the main acidolysis hydrocarbon in the U‐bearing beds, which shows a positive correlation with U‐content in the sandstones in the coal‐bearing series. Additionally, the δ13C in the carbonate cements of the U‐bearing sandstones indicates that the organic matters, associated with the coal around the sandstones, were involved in the carbonation, one important component of alteration in the Tuanyushan area. Recognition of the dual control of coal‐bearing series on the uranium mineralization is significant for the development of coal circular economy, environmental protection during coal utilization and the security of national rare metal resources. [ABSTRACT FROM AUTHOR]

Secondary copper smelting is an effective means of treating waste resources. During the smelting process, the viscous behavior of the smelting slags is essential for smooth operation. Therefore, the effects of Fe/SiO2 ratio and Fe2O3 contents on the viscous behavior of the FeO−Fe2O3−SiO2−8 wt%CaO−3 wt%MgO−3 wt%Al2O3 slag system were investigated. The slag viscosity and activation energy for viscous flow decrease with increasing Fe/SiO2 from 0.8 to 1.2, and increase as the Fe2O3 content increases from 4 wt% to 16 wt% at Fe/SiO2 ratio of 1.2. However, under the conditions of Fe/SiO2 of 0.8 and 1.0, the viscosity and activation energy for viscous flow show a minimum value at Fe2O3 content of 12 wt%. Fe2O3 exhibits amphoteric properties. In addition, the increase in Fe2O3 content raises the breaking temperature of the slag, while the Fe/SiO2 ratio has the opposite effect. Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy show that increases in Fe/SiO2 ratio lead to simplification of the silicate network structure, while increases in Fe2O3 content improves the formability of the network. This study provides theoretical support for the related research and application of secondary copper smelting. [ABSTRACT FROM AUTHOR]