Full-size pore structure characterization of deep-buried coals and its impact on methane adsorption capacity: A case study of the Shihezi Formation coals from the Panji Deep Area in Huainan Coalfield, Southern North China

Wei, Qiang; Li, Xianqing; Hu, Baolin; Zhu, Wenwei; Liang, Wanle; Sun, Kexin

doi:10.1016/j.petrol.2018.10.100

Cited by 59 publications

(61 citation statements)

References 54 publications

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“…Subsequently, a synclinal structure with an axial near EW was formed ( Figure 1 b). 31 , 33 In addition, a series of anticlines and synclines from north to south are as follows: Shangtang-Zhucun syncline, Chenqiao-Panji anticline, Xieqiao-gugou syncline, and Yongkang anticline. The Upper Paleozoic Carboniferous–Permian source rocks are coal-bearing strata, including the Taiyuan, Shanxi, and Shihezi Formations.…”

Section: Geological Settingmentioning

confidence: 99%

Composition, Origin, and Accumulation Model of Coalbed Methane in the Panxie Coal Mining Area, Anhui Province, China

Wei

Fang

et al. 2022

ACS Omega

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To investigate the geochemical characteristic, genetic types, and accumulation model of coalbed methane (CBM), 16 samples from a burial depth of 621–1494 m were collected in the Panxie Coal Mining Area of Huainan Coalfield. The results indicate that the samples are dominated by methane, and the concentrations are distributed in the range of 73.11–95.42%. The dryness coefficient is 0.77–1.00 (average, 0.93), and the ratio of methane to the sum of ethane and propane (C 1 /(C 2 + C 3 )) is 3.18–242.64 (average, 36.15). The δ 13 C CH 4 values are distributed in the range of −65.44 to −32.38‰ (average, −45.22‰), the δD CH 4 values are in the range of −226.84 to −156.82‰ (average, −182.93‰), and the δ 13 C CO 2 values are in the range of −19.7 to −10.1‰ (average, −15.51‰). CBM samples in the study area are dominated by thermogenic gases, followed by secondary biogenic gases with CO 2 reduction. For the percentages of different genetic gases, the distribution range of thermogenic gas is 70.11–97.86%, whereas that of biogenic gas is 58.65–77.86% for five samples from Zhangji, Panyi, Pansan, and Panbei Coalmines. Moreover, desorption-diffusion fractionation and the effect of groundwater dissolution occurred in the Panxie Coal Mining Area, and higher δ 13 C CH 4 values mostly existed in the deeper coal seams. Furthermore, the biogenic gases are more likely to be secondary biogenic gases generated by CO 2 reduction on the basis of data comparison, which is related to the flowing water underground. Accumulation models of different genetic types of CBM are correlated with the burial depth of coal seams, location, and type of faults and aquifers.

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Section: Geological Settingmentioning

confidence: 99%

Composition, Origin, and Accumulation Model of Coalbed Methane in the Panxie Coal Mining Area, Anhui Province, China

Wei

Fang

et al. 2022

ACS Omega

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“…The detailed analysis process and related basic data of coal seams have been shown in our previous reports. 6 , 7 , 22 , 26 …”

Section: Resultsmentioning

confidence: 99%

“…21 − 23 In addition, the coal seam has a triple structure of coal matrix, pores, and fractures. 24 − 26 The adsorbed gas dissociates from the coal matrix to fracture through a desorption–diffusion process and escapes outward under the action of differential pressure. 12 , 23 , 27 The gas desorption process is regarded as gas diffusion from a collection of spherical coal particles with a zero surface concentration and a constant initial gas concentration.…”

Section: Introductionmentioning

confidence: 99%

Effective Approach with Extra Desorption Time to Estimate the Gas Content of Deep-Buried Coalbed Methane Reservoirs: A Case Study from the Panji Deep Area in Huainan Coalfield, China

Wei

Fang³

et al. 2022

ACS Omega

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In this study, 11 core coal samples were collected from deep-buried coalbed methane (CBM) reservoirs with burial depth intervals of 900–1500 m for gas estimation content by a direct method. In desorption experiments, the cumulative gas desorption data were recorded within 2 h in the field on the basis of the China National Standard method. For accuracy, two improved methods were proposed. The results show that the gas contents of deep-buried coal samples based on the China National Standard and mud methods are 3.58–9.89 m 3 /t (average of 6.03 m 3 /t) and 3.74–10.05 m 3 /t (average of 6.20 m 3 /t), respectively. The proposed Langmuir equation and logarithmic equation methods exhibited nonlinear relationships between the cumulative desorption volume and desorption time, which yield values of 6.33–13.34 m 3 /t (average of 9.36 m 3 /t) and 6.15–13.86 m 3 /t (average of 10.37 m 3 /t), respectively. In addition, the two proposed methods combine the raw data within 2 h by the China National Standard method and additional desorption points during extra time, which are helpful for the ability of the hypothetical methods to calculate the gas content. The Langmuir equation method is a relatively more accurate method to estimate the gas content in comparison with the proposed logarithmic method, which is based on the relative error and comparison plots of actual data and simulated results. From the perspective of numerical value, the Langmuir equation method gives values 1.06–3.39 times (average of 1.86 times) those of the China National Standard method. These analyses show that the proposed Langmuir equation method with extra desorption points is an effective method to determine the gas content of deep-buried CBM reservoirs.

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“…The isothermal adsorption experiments targeted at the organic‐rich coal from different formations are commonly used to investigate the methane adsorption behavior on coal, which reveals the influences of various factors on the methane adsorption capacity, including gas pressure, 8,9 temperature, 10 moisture, 11,12 organic matter, 13 clay minerals, 8 pore structure, 14,15 and fracturing fluid, 16,17 and so forth. The pressure and temperature of CBM reservoirs are both increased with the increased depth.…”

Section: Introductionmentioning

confidence: 99%

Prediction of methane adsorption capacity in different rank coal at low temperature by the Polanyi‐based isotherm model

Zhao

Wang

et al. 2022

Energy Science & Engineering

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To investigate the adsorption properties of methane in coal under low temperatures, the isothermal adsorption tests of the three coal samples with different metamorphic degrees were conducted at the ambient temperatures of 253.15−293.15 K, and the low‐temperature nitrogen adsorption (LNA) tests of coal were also performed. Then a relational expression of equilibrium pressure, temperature, and methane adsorption capacity (T−P model) was deduced to predict the adsorption isotherm at any other temperature based on the Polanyi adsorption theory. The results show that the gas adsorption capacity of coal can be significantly increased at low temperatures (below 273.15 K), and the adsorbed methane in anthracite is obviously more than that in lean coal and coking coal by the virtue of possessing a larger micropore/transition pore volume and specific surface area. The relations between adsorption potential (ε) and adsorption volume (ω) at different temperatures can be drawn on one single logarithmic curve, and a suitable pseudo‐saturation pressure can be obtained by the improved Amankwah's method. The predicted adsorbed capacities via the T−P model are in line with the measured results at other equilibrium conditions, indicating that the model can contribute to the deep coalbed methane resources estimation and the gas disaster prevention and control in coal mines.

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Full-size pore structure characterization of deep-buried coals and its impact on methane adsorption capacity: A case study of the Shihezi Formation coals from the Panji Deep Area in Huainan Coalfield, Southern North China

Cited by 59 publications

References 54 publications

Composition, Origin, and Accumulation Model of Coalbed Methane in the Panxie Coal Mining Area, Anhui Province, China

Composition, Origin, and Accumulation Model of Coalbed Methane in the Panxie Coal Mining Area, Anhui Province, China

Effective Approach with Extra Desorption Time to Estimate the Gas Content of Deep-Buried Coalbed Methane Reservoirs: A Case Study from the Panji Deep Area in Huainan Coalfield, China

Prediction of methane adsorption capacity in different rank coal at low temperature by the Polanyi‐based isotherm model

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