Characterization of pore structure and its impact on methane adsorption capacity for semi-anthracite in Shizhuangnan Block, Qinshui Basin

Zhang, Miao; Fu, Xuehai

doi:10.1016/j.jngse.2018.10.001

Cited by 30 publications

(13 citation statements)

References 49 publications

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“…The VL and PL changed from 31.55 to 38.63 cm 3 /g (mean 36.51 cm 3 /g) and from 0.70 to 1.29 MPa (mean 1.01 MPa), respectively. According to Figure 9A, the adsorption curves were typical isothermal adsorption curve of high-rank coal, which is characterized by larger VL and smaller PL values compared with semi-anthracites and low-and medium-rank coals [16,18,48].…”

Section: Isothermal Adsorption and Its Kineticsmentioning

confidence: 99%

Effects of Pore Structures of Different Maceral Compositions on Methane Adsorption and Diffusion in Anthracite

et al. 2019

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The pore structure of coal reservoirs is the main factor influencing the adsorption–diffusion rates of coalbed methane. Mercury intrusion porosimetry (MIP), low-pressure nitrogen adsorption (LP-NA), low-pressure carbon dioxide adsorption (LP-CA), and isothermal adsorption experiments with different macerals were performed to characterize the comprehensive pore distribution and methane adsorption–diffusion of coal. On the basis of the fractal theory, the pore structures determined through MIP and LP-NA can be combined at a pore diameter of 100 nm to achieve a comprehensive pore structural splicing of MIP, LP-NA, and LP-CA. Macro–mesopores and micro-transitional pores had average fractal dimensions of 2.48 and 2.18, respectively. The Langmuir volume (VL) and effective diffusion coefficients (De) varied from 31.55 to 38.63 cm3/g and from 1.42 to 2.88 × 10−5 s−1, respectively. The study results showed that for super-micropores, a higher vitrinite content led to a larger specific surface area (SSA) and stronger adsorption capacity but also to a weaker diffusion capacity. The larger the average pore diameter (APD) of micro-transitional pores, the stronger the diffusion capacity. The diffusion capacity may be controlled by the APD of micro-transitional pores.

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Section: Isothermal Adsorption and Its Kineticsmentioning

confidence: 99%

Effects of Pore Structures of Different Maceral Compositions on Methane Adsorption and Diffusion in Anthracite

et al. 2019

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“…(a) Both are “self‐generation and self‐storage” reservoirs, meaning they can generate and store natural gas by themselves. (b) Both contain a certain amount of adsorbed gas . The adsorbed gas content accounts for more than 80% of the total CBM gas content, and its saturated methane adsorption capacity can exceed 10 m 3 /t .…”

Section: Introductionmentioning

confidence: 99%

“…(b) Both contain a certain amount of adsorbed gas . The adsorbed gas content accounts for more than 80% of the total CBM gas content, and its saturated methane adsorption capacity can exceed 10 m 3 /t . However, the adsorbed gas content in shale only accounts for 30%‐60% of the total gas content, with a saturated adsorption capacity that is usually in the 2‐4 m 3 /t range .…”

Section: Introductionmentioning

confidence: 99%

A comparative study of the nanopore structure characteristics of coals and Longmaxi shales in China

Zhou

Liu

Chen

et al. 2019

Energy Science & Engineering

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Both of the coalbed methane (CBM) and shale gas reservoirs are dominated by nanometer‐scale pores with their nanopore structures controlling the occurrence, enrichment, and accumulation of natural gas. Low‐pressure nitrogen gas adsorption (LP‐N2GA), low‐pressure carbon dioxide gas adsorption (LP‐CO2GA), high‐pressure methane adsorption (HPMA), and field emission scanning electron microscope (FE‐SEM) experiments were conducted on 14 different‐rank coal samples and nine Longmaxi shale samples collected from various basins in China to compare their nanopore characteristics. The FE‐SEM results indicate that the pore structures of both the coal and shale samples consist of nanometer‐sized pores that primarily developed in the organic matter. The types of their isothermal adsorption curves are similar. However, the coal and shale samples possess various hysteresis loops, which suggest that the nanopores in shale are open‐plated, whereas those in coal are semi‐open. Furthermore, the specific surface area (SSA) and pore volume (PV) of the micropores in coal are much larger than those of the mesopores, with the micropore SSAs accounting for 99% of the total SSA in the coal samples. However, the micropore SSAs in the shale samples only account 42.24% of the total SSA. These different nanopore structures reflect their different methane adsorption mechanisms. The methane adsorption of coal is primarily controlled by the micropore SSA, whereas that of shale is primarily controlled by the mesopore SSA. If we use mesopore SSA to analyze its impact on methane adsorption capacity of coal and shale, it will be mismatched. However, no mismatching relationship exists between the total SSAs and adsorption capacities of coal and shale. This study highlights the controlling effect of total SSA on methane adsorption capacity.

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“…Currently, there are many techniques for investigating coal pore characteristics, such as scanning electron microscopy (SEM) [16], small-angle X-ray scattering (SAXS) [17], nuclear magnetic resonance (NMR) [18], mercury intrusion porosimetry (MIP) [19], low-pressure nitrogen adsorption (LP-N 2 GA) [20], and low-pressure carbon dioxide adsorption (LP-CO 2 GA) [21]. Among the above methods, the LP-N 2 GA and LP-CO 2 GA methods have been widely used to quantitatively analyse the pore structure of coal [20][21][22][23][24]. Because activation diffusion is limited during N 2 adsorption at 77 K, the LP-N 2 GA method cannot be used to analyse pores less than 1.2 nm.…”

Section: Introductionmentioning

confidence: 99%

“…Whereas CO 2 can access pores within 0.3-1.5 nm at 273.15 K. Therefore, the LP-CO 2 GA method is more suitable for analysing micropores [21]. Based on the above experimental techniques, many studies have shown that the SSA of micropores is positively correlated with the saturated adsorption capacity of CBM [20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Effects of Pore Structure of Different Rank Coals on Methane Adsorption Heat

Wang

Zeng

et al. 2021

Processes

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Adsorption thermodynamic characteristics are an important part of the methane adsorption mechanism, and are useful for understanding the energy transmission mechanism of coalbed methane (CBM) migration in coal reservoirs. To study the effect of coal pore characteristics on methane adsorption heat, five different types of rank coals were used for low-pressure nitrogen, low-pressure carbon dioxide, and methane adsorption experiments. Pore structure and adsorption parameters, including maximum adsorption capacity and adsorption heat, were obtained for five coal samples, and their relationships were investigated. The results show that the low-pressure nitrogen adsorption method can measure pores within 1.7–300 nm, while the low-pressure carbon dioxide adsorption method can measure micropores within 0.38–1.14 nm. For the five coal samples, comprehensive pore structure parameters were obtained by combining the results of the low-pressure nitrogen and carbon dioxide adsorption experiments. The comprehensive results show that micropores contribute the most to the specific surface area of anthracite, lean coal, fat coal, and lignite, while mesopores contribute the most to the specific surface area of coking coal. Mesopores contribute the most to the pore volume of the five coal samples. The maximum adsorption capacity has a significant positive correlation with the specific surface area and pore volume of micropores less than 2 nm, indicating that methane is mainly adsorbed on the surface of micropores, and can also fill the micropores. The adsorption heat has a significant positive correlation with the specific surface area and pore volume of micropores within 0.38–0.76 nm, indicating that micropores in this range play a major role in determining the methane adsorption heat.

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Characterization of pore structure and its impact on methane adsorption capacity for semi-anthracite in Shizhuangnan Block, Qinshui Basin

Cited by 30 publications

References 49 publications

Effects of Pore Structures of Different Maceral Compositions on Methane Adsorption and Diffusion in Anthracite

Effects of Pore Structures of Different Maceral Compositions on Methane Adsorption and Diffusion in Anthracite

A comparative study of the nanopore structure characteristics of coals and Longmaxi shales in China

Effects of Pore Structure of Different Rank Coals on Methane Adsorption Heat

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