Adsorption Capacity Of Coal Research Articles

Effect of water occurrences on methane adsorption capacity of coal: A comparison between bituminous coal and anthracite coal

In this study, an NMR fluid typing method was applied to two typical anthracite and high volatile bituminous coals to identify different occurrence states of water (adsorbed and non-adsorbed water), and multiphase methane (adsorbed, porous medium confined, and bulk methane) and investigate the effect of the water occurrence states on methane adsorption capacity. First, results of isothermal adsorption analysis conducted using the NMR method was compared to those from conventional volumetric method to verify the precision of the NMR method. Then the influence of adsorbed water and non-adsorbed water on methane adsorption was examined based on two parallel treatments. For bituminous coal, the adsorbed water remarkably reduced the Langmuir adsorption volume, whereas adding non-adsorbed water had no effect on gas adsorption. In contrast, for anthracite coal, the methane adsorption capacity revealed a downward trend with increase in both adsorbed water and non-adsorbed water. The explanation is that adsorption competition between water molecules and methane gas molecules can constrain further adsorption of methane on the coal matrix. Thus, adsorbed water negatively impacts gas adsorption for both anthracite and bituminous coal. In terms of non-adsorbed water, due to the superior pore conductivity and hydrophilia of bituminous coal, methane gas can easily pass through the pores in the presence of non-adsorbed water, compared to anthracite, where water blocking and the Jamin effect tend to occur. Even water droplets formed because of anthracite’s hydrophobicity can utterly block the pore throats, resulting in a continuous decrease in methane adsorption capacity. The implications of this study are important for better understanding the influence of various occurrence states of water on the adsorption/desorption processes in unconventional reservoirs.

New insights into the CH4 adsorption capacity of coal based on microscopic pore properties

The objective of this study is to quantitatively describe the CH4 adsorption capacity of coal through microscopic pore properties. In this work, the micropore volume distributions (MPVDs) of granular coal samples from six collieries were obtained by low-pressure CO2 adsorption (LPGA-CO2), and the external specific surface areas (SSAs) were calculated using low-pressure N2 adsorption (LPGA-N2). Based on micropore filling and monolayer coverage theories, the micropores were assumed to be cylindrical to obtain the distribution of CH4 in pore structures with different scales. For the coal samples used in this study, micropores were common, whose SSAs accounted for most of the total SSAs (90.39–99.58%), and the micropore volumes accounted for 75.61–96.55% of total pore volumes. The quantity of CH4 adsorbed in the form of micropore filling account for 74–99% of the total amount adsorbed, while the amount of CH4 adsorbed by micropores in the size range of 0.38–0.76 nm was 38–55% of the total amount adsorbed and accounted for the largest proportion in the nine adsorption areas partitioned according to the number of CH4 molecules occupying micropores with different scales. Based on a combination of the high-pressure CH4 adsorption (HPGA-CH4) results, the estimated Langmuir volumes are in close agreement with the measured Langmuir volumes, which demonstrates that the CH4 adsorption capacity of the coal is determined by both the accessible MPVD and external SSAs. The results of this study may be significant for understanding the pore networks and the CH4 adsorption mechanism in coal under in situ conditions.

Influence of reservoir properties on the methane adsorption capacity and fractal features of coal and shale in the upper Permian coal measures of the South Sichuan coalfield, China

Pore structure plays an essential role in the reservoir heterogeneity and methane adsorption capacity. Significant progress has been made in the pore structure classification of porous materials (such as coal and shale). Considering the pore structure characterization of the coal measures and the measuring range of high-pressure mercury intrusion porosimetry and low-pressure N2/CO2 gas adsorption, an integrated classification for coal and shale is provided. They are micropore (<2 nm), mesopore (2–100 nm), macropore A (100 nm–1 µm), macropore B (1–10 µm), and micro-fracture (>10 µm). For coal and shale samples from Guxu mining area, the micropores and mesopores largely control the gas adsorption while micro-fractures and macropore B are significant for the storage and flow of free gas. The fractal dimensions calculated from limited N2 adsorption data are not suitable for the coal samples which are not developed in mesopore and macropore A; these samples are precisely corresponding to the N2 adsorption/desorption isotherms of group B (reversible isotherm). Furthermore, the main factors influencing the methane adsorption capacity of coal and shale in the coal measures are micropore frequency, micro-fracture width, clay mineral composition, and total organic carbon content.

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

AbstractBoth 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.

Coalbed methane adsorption capacity related to maceral compositions

Maceral compositions take a great role in coalbed methane adsorption. Two controversial viewpoints coexist on the effect of maceral compositions to coalbed methane adsorption. One is vitrinite has better adsorption capacity than inertinite and the other is inertinite has enhanced adsorption capacity than vitrinite. In order to clarify this issue, a series of coal samples were collected and highly purified vitrinite and inertinite concentrates were gained by heavy-fluid flotation and centrifugal separation. Isothermal adsorption experiments of methane were performed to these concentrates with equilibrium moisture and their ultimate adsorption volume were obtained finally. The results show that the adsorption capacity of vitrinite is weaker and the capacity of inertinite is stronger for low-rank coal. For high-rank coal, the adsorption capacity of vitrinite is stronger and the capacity of inertinite is weaker. Along with the increase of coal rank, the adsorption capacity of vitrinite rises gradually and the adsorption capacity of inertinite declines little by little. This result shows that the adsorption capacity of coal to methane not only relates to contents of vitrinite and inertinite, but also relates to metamorphic grade of the coal, because with the increase of metamorphism of coal, molecular structure, functional group and pore characteristic of vitrinite and inertinite change gradually, which results in tremendous changes in the adsorption capacity of coal.

Experiment study on the correlation between the CO2 adsorption capacity and electrical resistivity of coal with temperature effect

AbstractThe main objective of this study is to investigate the relationship between the CO2 adsorption capacity and electrical resistivity of coal. The H‐Sorb 2600 high pressure gas adsorption analyzer is used to measure the CO2 sorption capacity in the temperature range of 25–55°C for anthracite coal. In addition, the TH2811D LCR meter is used to examine the electrical resistivity of raw coal samples and coal briquettes from 15°C to 65°C. The results indicate that there is a critical pressure threshold depending on the coal types and the pattern of changes in CO2 adsorption capacity changes when this threshold is exceeded. The electrical resistivity of raw coal samples decreases linearly and then slightly decreases at temperatures above 45°C and the electrical resistivity decreases approximately linearly from 15°C to 65°C for the coal briquettes due to lower compactness compared with the raw coal samples. The CO2 adsorption capacity has a power function with the electrical conductivity of the raw coal samples and coal briquettes. The power exponent of the power function is related to the porosity of coal. The results of the experiments indicate that it is effective to estimate the CO2 adsorption capacity of coal from the electrical conductivity. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

Sorption capacity of Indian coal and its variation with rank parameters

The study of gas sorption characteristics is important for practical assessment of coal bed methane (CBM) production and CO2 sequestration in coal seam. Adsorption isotherm is one of the critical parameters for the establishment of production as well as injection well. Adsorption isotherm provides information about the reservoir conditions and critical desorption pressure as well as volume of gas that can be sequestered in deep coal seam. Alteration in sorption isotherm reflects the increase or decrease of the gas production as well as CO2 sequestration. Therefore, in this paper, experimental investigation was carried out to determine the CO2/CH4 sorption capacity of five different coal samples taken from different locations of Jharia coalfield (Moonidih area) of Gondwana basin. Gas sorption capacity was determined at 27 °C temperature and up to 7.5 MPa pressure. CO2 adsorption was observed to be higher than that of the CH4. The sorption ratio of CO2/CH4 varied from 1.6:1 to 1.2:1 for all coal samples. Furthermore, the experimental results were correlated using established Langmuir, Freundlich, Temkin and D–R isotherm models. Experimentally obtained values satisfactorily fitted to the Langmuir and Freundlich model with comparable accuracy. The excess adsorption capacity of coal was also compared with different rank parameters to understand the variation of sorption capacity with rank of coal.

Fractal study of adsorption-pores in pulverized coals with various metamorphism degrees using N2 adsorption, X-ray scattering and image analysis methods

As a highly heterogeneous material, the porous structure of coal is usually described by fractal dimension, which generally can be obtained by gas adsorption, light scattering and image analysis methods. In this paper, the pore structure (pore volume and specific surface area) and adsorption performance (Langmuir volume and Langmuir pressure) of 12 different rank coal samples were investigated by liquid nitrogen adsorption experiment (LNA) and methane isotherm adsorption experiment. And the fractal characteristics of these coals were studied by three fractal dimensions D1, D2 and D3 acquired from LNA and small angle X-ray scattering (SAXS) and scanning electron microscopy (SEM), respectively. Results indicate that the adsorption pore volume and specific surface area show U-shaped evolutionary trends during the coalification process. The changes of pore volume and specific surface area are dominated by the mechanical compaction and dehydration effects before the second coalification jump (Ro,max = 1.3%), while they are then mainly controlled by concomitant metamorphic pores until the fourth coalification jump (Ro,max = 3.7%). Langmuir volume first increases and then reaches a steady value at the third coalification jump (Ro,max = 2.5%) with the increasing coal rank, however, Langmuir pressure monotonously decreases during the whole coalification process. D1 and D2 exhibit a dramatically increase from Ro,max = 0.6% to Ro,max = 2.0% and then a slowly rise when Ro,max increases from 2.0% to 3.5%, which is relevant to the changes of pore structure and macromolecule structure in coal. D3 increases at a low speed first and then increases at a high speed with the increasing coal rank, which reflects the surface morphology of pores in coal. Fractal dimension D1, D2 and D3 can be used to depict the methane adsorption properties of coal in varying metamorphism degrees. Generally, D2 is larger than D1, which is because N2 adsorption can probe more macropores but SAXS can detect more micropores. Additionally, D1, D2 and D3 are all negatively related to PL. Our investigations also confirm that SAXS may be more superior to character the adsorption capacity of coal according to its highest relativity. This work clarifies the intrinsic sense and difference for characterising the surface irregularity by various methods, and provides an understanding for the experimental means relating to adsorption pores.

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

To determine the pore structure characteristics and its effect on the adsorption capacity of semi-anthracite, high pressure mercury injection (HPMI), Low pressure nitrogen gas adsorption (LP-N2GA), Low pressure carbon dioxide gas adsorption (LP-CO2GA) and isotherm adsorption experiments were carried out on eight coal samples collected from the Shizhuangnan Block. The results show that the semi-anthracite reservoirs predominantly developed semi-open pores with poor connectivity and various pore morphology. The combined pore size distribution (PSD) from results of HPMI, LP-N2GA and LP-CO2GA indicated that the super-micropores in semi-anthracite reservoirs are most developed, providing the main storage space, accounting for 80.75% of the total TPV and 99.69% of the total SSA, followed by macropores. Additionally, the pore volume and SSA distributions of semi-anthracite reservoirs are unimodal with peak values present at 0.5–0.6 nm, indicating that pores with pore diameter between 0.5 and 0.6 nm are the largest contributors to TPV and SSA, accounting for 40.09% of the TPV and 56.95% of the total SSA. The super-micropores have a controlling factor on the adsorption capacity of semi-anthracite reservoirs. Vitrinite-rich coals developed stronger adsorption capacity as the vitrinite is rich in super-micropores whereas there are no obvious correlations between inertinite content with super-micropore SSA and VL. Additionally, mineral has a negative effect on the adsorption capacity of coals by inhibiting the development level of super-micropores. The combination application of HPMI, LP-N2GA and LP-CO2GA can more accurately reflect the pore structure of coal reservoir, especially for super-micropores.

Methane adsorption characteristics and its influencing factors of the medium-to-high rank coals in the Anyang-Hebi coalfield, northern China

The variation of coal rank in the Anyang-Hebi (Anhe) coalfield has the phenomenon of anti-Hilt law, which makes the coalfield distinctive for coalbed methane exploration research. The methane adsorption characteristics and influencing factors of the medium-to-high rank coal samples of the Shanxi Formation in this coalfield were analyzed. The results indicate that the Langmuir volume ( VL) of coals in the shallow western part of the Anhe coalfield is generally higher than that in the deep eastern part. The coal rank and the coal macerals are the dominant factors that influence the methane adsorption capacity of coals in this anti-Hilt law area. The methane adsorption capacity, represented by VL, first increases and then decreases with the coal rank, and the highest VL value corresponds to the maximum vitrinite reflectance of ∼2.1%. The adsorption capacity has a positive correlation with the vitrinite and the moisture content, a negative relationship with the inertinite content. In general, the adsorption capacity of coal samples shows a “V-shaped” change with the ash yield, and the lowest VL value corresponds to the ash yield of ∼9%. A prediction model of the gas content of the Anhe coalfield was proposed based on changes of the methane adsorption capacity and principal component analysis. Areas with a critical depth ranging from 400 m to 700 m are suggested to be methane enrichment regions for coalbed methane exploration in the Anhe coalfield.

Relationship between Maceral of Coal and Coal-bed Methane adsorption ability in Sihe Coalmine of Qinshui Basin, China

Maceral components and its content of coal were divided based on the microscopic characteristics of coal. The Langmuir volume and the Langmuir pressure were tested, and the Langmuir volume represents the adsorption capacity of coal. The formation of coal bed methane is affected by the partition of the maceral components in coal. Therefore, the relationship between maceral composition and coal bed methane adsorption capacity of coal was analyzed. The results show that the maceral components of coal are dominated by vitrinite and inertinite in the study area, and the content of inertinite is below 32%. The vitrinite group has a negative linear correlation with the Langmuir volume, and the inertia composition has a positive linear correlation with it. The cellular structures in the inertinite are the main site of coal bed methane enrichment. The microstructure of coal affects the coalbed methane content and the stage of hydrocarbon generation in coal. This indicates that the microstructure of coal is one of the important factors influencing the adsorption capacity of coal seam.

Distribution law of temperature changes during methane adsorption and desorption in coal using infrared thermography technology

Gas adsorption and desorption is a thermodynamic process that takes place within coal as temperature changes and that is related to methane (CH4) storage. As infrared thermographic technology has been applied in this context to measure surface temperature changes, the aim of this research was to further elucidate the distribution law underlying this process as well as the thermal effects induced by heat adsorption and desorption in coal. Specimens of two different coal ranks were used in this study, and the surface temperature changes seen in the latter were detected. A contour line map was then drawn on the basis of initial results enabling a distribution law of temperature changes for samples. The results show that different regions of coal sample surfaces exhibit different heating rates during the adsorption process, but they all depends on gas storage capacity to a certain extent. It proposes a correlation coefficient that expresses the relationship between temperature change and gas adsorption capacity that could also be used to evaluate the feasibility of coalbed CH4 extraction in the field. And finally, this study is deduced a method to reveal the actual adsorption capacity of coal or CH4 reservoirs in in situ coal seams.

Methods and Models for Analyzing Methane Sorption Capacity of Coal Based on Its Physicochemical Characteristics

The authors study the influence of physicochemical parameters on methane adsorption capacity of coal and offer the analytical method for the methane adsorption capacity for three-phased condition of methane. It is found that in the depth interval to 300 m below surface, methane adsorption capacity measured in lab can exceed natural gas content of coal obtained from geological exploration data by 30%, and the change in the thermodynamic condition of coal–methane system brings irreversible physicochemical consequences in terms of the altered ratios of physical states of the main components. There is no linear connection between natural gas content of a coal bed and its methane adsorption capacity with respect to occurrence depth. The application of Big Data in treatment and interpretation of large data flows is described. The theoretical data predicted using the proposed method and the experimental data on methane content of Kuzbass coal agree.

Investigations of CO2-water wettability of coal: NMR relaxation method

Carbon geo-sequestration (CGS) and recovery enhancement with carbon dioxide injection (CO2-ECBM) have brought increasing focus on the CO2 and water wettability of coal. The CO2 and water contact angles measured using existing conventional methods, such as the pendent drop tilting plate technique and the captive-bubble technique, show low reproducibility due to coal heterogeneity and operational complexity. In this study, a novel NMR-based approach was developed to evaluate the CO2 and water wettability of coal. The experimental results of nine bituminous and anthracite coals show that water wettability can be linearly correlated with the changes of the T2 spectra peak positions. Based on the measured contact angle from the profile of the water adhering to the coal powder disc and the T2 from the NMR of coal powder, we proposed a linear formulation to evaluate the contact angle using the change of T2g of P3. Using this method, we analyzed the CO2-water wettability characteristics of coal. The results show that CO2 reduces the water wettability of coal. Low temperature and/or high CO2 pressure can enhance the CO2 wettability of coal. The change of water-coal wetting behavior with injection of CO2, is resulted by three factors: change of CO2 adsorption capacity of coal, change of interfacial tension, and dissolution of CO2 in water. This study makes it possible to evaluate changes in the water and CO2 wettability of coal, which is essential for evaluating the fluid-interaction mechanisms during the process of carbon geo-sequestration and enhanced coalbed methane recovery with carbon dioxide injection.

Study on Coal Methane Adsorption Behavior Under Variation Temperature and Pressure-Taking Xia-Yu-Kou Coal for Example

Based on the Langmuir volume and Langmuir pressure of Xiao-Yu-Kou #3 coal’s methane adsorption, Li’s adsorption-flow equation’s parameters have been calculated. LI adsorption-flow equation obtained can visually show and quantitatively calculate that how and how much variation temperature and pressure change the absorption capacity. Partial differential equation characterizes temperature has negative effects and pressure has positive effects. Therefore, under variation temperature and pressure conditions, coal adsorption capacity would have the maximum value.

Experimental investigation on variation of physical properties of coal samples subjected to microwave irradiation

The gas drainage rate of low-permeability coal seam is generally less than satisfactory. This leads to the gas disaster of coal mine, and largely restricts the extraction of coalbed methane (CBM), and increases the emission of greenhouse gases in the mining area. Consequently, enhancing the gas drainage rate is an urgent challenge. To solve this problem, a new approach of using microwave irradiation (MWR) as a non-contact physical field excitation method to enhance gas drainage has been attempted. In order to evaluate the feasibility of this method, the methane adsorption, diffusion and penetrability of coal subjected to MWR were experimentally investigated. The variation of methane adsorbed amount, methane diffusion speed and absorption loop for the coal sample before and after MWR were obtained. The findings show that the MWR can change the adsorption property and reduce the methane adsorption capacity of coal. Moreover, the methane diffusion characteristic curves for both the irradiated coal samples and theoriginal coal samples present the same trend. The irradiated coal samples have better methane diffusion ability than the original ones. As the adsorbed methane decreases, the methane diffusion speed increases or remain the same for the sample subjected to MWR. Furthermore, compared to the original coal samples, the area of the absorption loop for irradiated samples increases, especially for the micro-pore and medium-pore stage. This leads to the increase of open pores in the coal, thus improving the gas penetrability of coal. This study provides supports for positive MWR effects on changing the methane adsorption and improving the methane diffusion and the gas penetrability properties of coal samples.

Efficiency of Carbon Dioxide Storage and Enhanced Methane Recovery in a High Rank Coal

The high affinity and adsorption capacity of coal to carbon dioxide provides an alternative approach for the enhanced recovery of methane from unminable coalfields (CO2-ECBM) by which a potential solution for long-term CO2 sequestration in deep geological formations can also be achieved. However, due to chemomechanical effects induced by the interactions between CO2 and coal, the effective methane production and carbon dioxide storage can be degraded which has caused uncertainties about the techno-economic feasibility of the CO2-ECBM process. This study presents an experimental investigation that aims to address key knowledge gaps related to the efficiency of CO2 storage and CH4 recovery in high rank coals for which a comprehensive experimental data set and analysis are largely missing. Competitive displacements of CH4 with N2 or CO2 in an anthracite coal sample from a South Wales coalfield have been studies, based on a series of core flooding experiments. The results show that the N2 breakthrough time (t...

Pyrolysis characteristic of coals with different metamorphic grades and its instruction to coalbed methane development

PurposePyrolysis for coal gas generation changes the composition, pore structure, permeability and adsorption capacity of coal. This work aims to discuss the utilization of coal pyrolysis on enhancing coalbed methane (CBM) production in the Gujiao area, Shanxi province, China.Design/methodology/approachThis research was conducted mainly by the methods of thermogravimetry mass spectrometry (TG-MS) analysis, liquid nitrogen adsorption experiment and methane isothermal adsorption measurement.FindingsThe results can be concluded as that 400-700°C is the main temperature range for generating CH4. Pore volume and specific surface area increase with increasing temperature; however, the proportion of micro pore, transition pore and macro pore has no difference. The optimum temperature for enhancing CBM production should be letter than 600°C because the sedimentation of tar and other products will occupy some pores and fissures after 600°C.Originality/valueHere in, to accurately recognize the suitable maximum temperature for heating development, a method enhancing CBM production, TG-MS, was adopted to analyze the products and the weight loss of coals with different ranks in the Gujiao area at temperature of 30-1,100°C. And then the pore structure, porosity, permeability, methane adsorption capacity and thermal maturity of coals during pyrolysis were investigated with increased temperature from 30°C to 750°C. On these bases, the favorable condition for enhancing CBM production and the thermal evolution of coal were recognized.

Experimental study of the adsorption-induced coal matrix swelling and its impact on ECBM

Carbon dioxide (CO2) enhanced coalbed methane (ECBM) is an effective method to improve methane (CH4) production and this technology has already been used to increase gas production in several field trials worldwide. One major problem is the injection drop in the later period due to permeability decrease caused by coal matrix swelling induced by CO2 injection. In order to quantify the swelling effect, in this work, coal samples were collected from the Bulli coal seam, Sydney Basin and adsorption tests with simultaneous matrix swelling measurement were conducted. The adsorption and swelling characteristics were analyzed by measuring the adsorption mass simultaneously with the strain measurement. Then experiments were conducted to replicate the ECBM process using the indirect gravity method to obtain the swelling strain change with CO2 injection. The results show that the coal adsorption capacity in CO2 is almost two times greater than that in CH4, and nitrogen adsorption is the least among these gases. A Langmuir-like model can be used to describe the strain with the gas pressure and the swelling strain induced by gas adsorption has a linear relationship with gas adsorption quantity. Moreover, swelling strain increase was observed when CO2 was injected into the sample cell and the swelling strain was almost the sum of the strains induced by different gases at corresponding partial gas pressure.

Pore Structure Characterization of Different Rank Coals Using N2 and CO2 Adsorption and Its Effect on CH4 Adsorption Capacity: A Case in Panguan Syncline, Western Guizhou, China

To determine the pore structure characteristics of different coal ranks in Panguan syncline, both N2 adsorption–desorption (LP-N2GA) and CO2 adsorption (LP-CO2GA) were carried out with the goal of revealing the differentiation evolution of total pore volume (TPV), specific surface area (SSA), pore size distribution (PSD), and pore shape of 14 coal samples, and the influences of SSA to adsorption capability at different sizes (supermicroporous < 2 nm, micropore: 2–10 nm, transition pore: 10–100 nm) were further discussed. Density functional theory (DFT) is used for the determination of pore structure parameters to ensure its accuracy. Results show that the pore shape in the Panguan area is mostly the semi-open pores with poor connectivity (e.g., wedge-shaped, cylindrical, and slit-shaped pores with one closed side). Only a small amount of the pores is in open shapes (e.g., slit-shaped pores or cylindrical pores with two ends open). For most of the coal samples, the PSDs of pores tested by LP-N2GA appear to be multimodal, and the N2-TPV is mainly from the contribution of the transition pore (73.69–95.21%), followed by the micropore. The PSDs of supermicroporous (tested by LP-CO2GA) appear to be bimodal, with two peak values present at 0.52–0.61 nm and 0.82–0.87 nm, respectively, and a bigger pore volume distribution interval corresponds to a higher specific surface area. The N2-SSA (pore diameter ranges from 2 to 100 nm) mainly comes from the contribution of the pores 2–3 nm in diameter, and a bigger N2-TPV means a higher N2-SSA. The CO2-SSA (pore diameter ranges from 0.489 to 1.083 nm) which has a better positive linear correlation with Langmuir volume is related to CO2-TPV and the distribution frequency of pore volume at different pore sizes, and the contribution rate of CO2-SSA to the total SSA (CO2-SSA + N2-SSA) reaches 99%, indicating that supermicroporous has a significant effect on the coal adsorption capacity. With the increase of the vitrinite reflectance (Ro,ran, 0.83 → 2.27%), the N2-SSA increase gradually, and its increase tendency presents to be a half-reversed “U” shape in the whole, while the CO2-SSA presents an extremely significant linear increase tendency. Accordingly, the Langmuir volume (2.61 → 21.26 m3/t) also displays a linear growth tendency with the increasing vitrinite reflectance. The results of this study will provide guidance to the CBM development in the Panguan area.