Significance of analytical particle size in low-pressure N2 and CO2 adsorption of coal and shale

Mastalerz, María; Hampton, LaBraun; Drobniak, Agnieszka; Loope, Henry M.

doi:10.1016/j.coal.2017.05.003

Cited by 144 publications

(104 citation statements)

References 24 publications

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“…Currently, the low-pressure nitrogen gas adsorption test (LPN 2 GA) has become an effective method for characterizing adsorption pore structure in porous media among various testing technologies. 3 − 6 However, it has limitations with regard to accurate characterization of the micropore structure because of the large molecular diameter (0.36 nm) of N 2 and the instrument precision. Due to its smaller molecular diameter (0.33 nm) and stronger adsorption capacity, CO 2 can enter pores with diameters ranging from 0.3 to 1.5 nm at a temperature of 273.15 K. 7 Therefore, the CO 2 adsorption test (LPCO 2 GA) is considered to be the best method for the quantitative characterization of micropores.…”

Section: Introductionmentioning

confidence: 99%

Multifractal Analysis in Characterizing Adsorption Pore Heterogeneity of Middle- and High-Rank Coal Reservoirs

et al. 2020

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Nanopore heterogeneity has a significant effect on adsorption, desorption, and diffusion processes of coalbed methane. The adsorption pore size distribution heterogeneity was calculated by combining N 2 with CO 2 adsorption data, and factors affecting multifractal and single-fractal dimensions were studied. The results indicate that pore size distribution of micropores (with pore diameters smaller than 2 nm) and meso–macro-pores (with pore diameters between 2 and 100 nm) in coal samples exhibit typical multifractal behavior. The overall heterogeneity of micropores in high-rank coal samples is higher than that in the middle-rank coal samples. The low-probability measure areas control the overall heterogeneity of pores with diameters of 0.40–1.50 nm. The high-probability measure area heterogeneity and spectral width ratio have a higher linear correlation with coal rank and pore structure parameters than those of low-probability measure areas. Heterogeneity of high-probability measure areas and overall pore size distribution are controlled by pores with diameters of 0.72–0.94 nm. Multifractal parameters of meso–macro-pores have no clear relationship with coal rank. The pore volume of 2–10 nm diameter shows a good linear correlation with heterogeneity of low-probability measure areas, and pores of this diameter range are the key interval that affected pore size distribution heterogeneity. The single-fractal dimension obtained using the Frenkel–Halsey–Hill (FHH) model shows a positive linear correlation with heterogeneity of the low-probability measure areas. It indicates that this parameter can effectively characterize the pore size distribution heterogeneity of low-probability measure areas in meso–macro-pores.

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Section: Introductionmentioning

confidence: 99%

Multifractal Analysis in Characterizing Adsorption Pore Heterogeneity of Middle- and High-Rank Coal Reservoirs

et al. 2020

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“…The relative pressure ( P / P 0 ) for N 2 adsorption ranges from 0.001 to 0.995. The instrument’s computer software automatically generates adsorption isotherms and calculates surface areas, pore volumes, and pore size distributions based on multiple adsorption theories [32,33,50].…”

Section: Samples and Methodsmentioning

confidence: 99%

Nanopore Structure and Fractal Characteristics of Lacustrine Shale: Implications for Shale Gas Storage and Production Potential

Chen

Jiang

et al. 2019

Nanomaterials

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In order to better understand nanopore structure and fractal characteristics of lacustrine shale, nine shale samples from the Da’anzhai Member of Lower Jurassic Ziliujing Formation in the Sichuan Basin, southwestern (SW) China were investigated by total organic carbon (TOC) analysis, X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), and low-pressure N2 adsorption. Two fractal dimensions D1 and D2 (at the relative pressure of 0–0.5 and 0.5–1, respectively) were calculated from N2 adsorption isotherms using the Frenkel–Halsey–Hill (FHH) equation. The pore structure of the Lower Jurassic lacustrine shale was characterized, and the fractal characteristics and their controlling factors were investigated. Then the effect of fractal dimensions on shale gas storage and production potential was discussed. The results indicate that: (1) Pore types in shale are mainly organic-matter (OM) and interparticle (interP) pores, along with a small amount of intraparticle (intraP) pores, and that not all grains of OM have the same porosity. The Brunauer–Emmett–Teller (BET) surface areas of shale samples range from 4.10 to 8.38 m2/g, the density-functional-theory (DFT) pore volumes range from 0.0076 to 0.0128 cm3/g, and average pore diameters range from 5.56 to 10.48 nm. (2) The BET surface area shows a positive correlation with clay minerals content and quartz content, but no obvious relationship with TOC content. The DFT pore volume shows a positive correlation with TOC content and clay minerals content, but a negative relationship with quartz content. In addition, the average pore diameter shows a positive correlation with TOC content and a negative relationship with quartz content, but no obvious relationship with clay minerals content. (3) Fractal dimension D1 is mainly closely associated with the specific surface area of shale, suggesting that D1 may represent the pore surface fractal dimension. Whereas fractal dimension D2 is sensitive to multiple parameters including the specific surface area, pore volume, and average pore diameter, suggesting that D2 may represent the pore structure fractal dimension. (4) Shale with a large fractal dimension D1 and a moderate fractal dimension D2 has a strong capacity to store both adsorbed gas and free gas, and it also facilitates the exploitation and production of shale gas.

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“…Mastalera et al [25] compared the pore structures by assigning different particle sizes: from chunks to the particle size less than 0.063 mm (230 mesh). Hazra et al [26] divided the particle sizes into five different groups and studied their pore structures in a larger range of sizes, ranging from <1 mm (18 mesh) to <53 μm (270 mesh).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Particle Size on the Interpretation of Pore Structure of Shale by N2 Adsorption

Lyu

Zhou

et al. 2021

Geofluids

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Gas adsorption experiments are becoming one of the most common methods to quantify and analyze the pore structures of shale samples in the petroleum industry. In this regard, particle size of the specimen plays an important role in the results that could ultimately affect the pore structure interpretation. Hence, in this study, five shale samples at different thermal maturity levels are picked, and all are crushed into different groups of particle sizes: less than 40 mesh (<375 μm), less than 60 mesh (<250 μm), less than 80 mesh (<187.5 μm), and less than 100 mesh (<150 μm). Next, N2 adsorption is used to characterize the pore structures of the samples within different particle sizes. Furthermore, to interpret the data, several attributes such as the pore volume, surface area, fractal dimension (from the fractal analysis), and heterogeneity index (from the multifractal analysis), are studied and compared between the samples and particle size intervals to provide us with the effect that particle size could have on the pore structure analysis. The results showed that as the particle size varies, the pore structures of the shale samples could get affected. Based on the comparison of the results, it is recommended that a suitable particle size for the shale pore structure characterization in N2 adsorption experiments should be less than 60 mesh (<250 μm).

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Significance of analytical particle size in low-pressure N2 and CO2 adsorption of coal and shale

Cited by 144 publications

References 24 publications

Multifractal Analysis in Characterizing Adsorption Pore Heterogeneity of Middle- and High-Rank Coal Reservoirs

Multifractal Analysis in Characterizing Adsorption Pore Heterogeneity of Middle- and High-Rank Coal Reservoirs

Nanopore Structure and Fractal Characteristics of Lacustrine Shale: Implications for Shale Gas Storage and Production Potential

The Effect of Particle Size on the Interpretation of Pore Structure of Shale by N2 Adsorption

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