Insight into the pore structure of Wufeng-Longmaxi black shales in the south Sichuan Basin, China

Zhu, Haihua; Zhang, Tingshan; Liang, Xing; Zhang, Zhao; Zhang, Lei

doi:10.1016/j.petrol.2018.08.061

Cited by 18 publications

(13 citation statements)

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“…Molecular simulation is the common effective method to study shale gas adsorption behavior because of the characteristics of shale pores, whose average pore size is 3–5 nm. − Based on realistic kerogen model, Zhao et al studied the effects of water content on methane adsorption capacity using the molecular dynamics (MD) and Monte Carlo (MC) simulation methods . Although some molecular dynamics-based shale kerogen pores were constructed to investigate the adsorption of methane in shale, Huang et al considered the factors of pressures, temperatures, geological depths, kerogen maturity, moisture content, and kerogen organic type on adsorption of CH 4 and CO 2 using GCMC and MC methods. ,, Zhou and Collell et al figured out the effect of pore size on adsorption.…”

Section: Introductionmentioning

confidence: 99%

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms

et al. 2019

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Although the focus of shale gas recovery has shifted to CO 2 sequestration with enhanced gas recovery (CS-EGR) for overcoming the low recovery efficiency, the adsorption and recovery mechanism of methane (CH 4 ) and carbon dioxide (CO 2 ) considering the effect of pore structures remains to be revealed. In this work, we focus on the influence of pore structures on adsorption behaviors of CH 4 and CO 2 at different geological depths and recovery process in different pore structures with various injection gas pressures. The results demonstrate that the excess adsorption capacity of CH 4 and CO 2 is in the order of cylinder-shaped > bottleneck > wedge-shaped > slit-shaped. The adsorption capacities of both CH 4 and CO 2 increase initially with geological depth until reaching maximum and then decrease with the depth going deeper. As for competitive adsorption of CH 4 and CO 2 , the pore structures do not have much influence on the selectivity. However, the pore structures have significant impact on shale gas recovery, and the difficulty of CH 4 molecules being displaced in various pore structures is ordered as cylinder-shaped > bottleneck > slit-shaped > wedge-shaped pores, which is consistent with the system resistance. The displacement efficiency of CH 4 in cylinder-shaped pores is about 59%, much less than in other pore structures. The injection pressure has a negative effect on the speed of shale gas recovery and displacement efficiency of CH 4 for the reason that more molecules aggregate into clusters near the pore throat and the flow blocking effect become more obvious when the injection pressure increases. Based on this actuality, we proposed a probable reliable method for CS-EGR: lower injection pressure is initially set to improve recovery efficiency, and higher pressure is finally used to increase CO 2 sequestration amount.

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Section: Introductionmentioning

confidence: 99%

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms

et al. 2019

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“…For the Wufeng-Longmaxi shale, Guo et al reported that the organic pores have a positive contribution to porosity if Ro is less than 2.8% in the Sichuan Basin . Huang and Zhu et al have reported that the Ro of OM in Wufeng-Longmaxi formation in the study area is in the range from 0.7% to greater than 3.0%, with an averafe of 2.19%, among which the samples with Ro between 1.3 and 3.0% take the largest part. − Thus, a large number of organic pores flourish in the study area because the R o of the Wufeng-Longmaxi shale is less than 2.2%. The study unveiled a positive correlation between thermal maturity and the specific surface area in the study area (Figure b).…”

Section: Discussionmentioning

confidence: 91%

“…The results showed a significant influence of mineral content on pore occurrence. As shown in the figures, the correlation coefficient of clay mineral content and porosity is 0.5, and the 45 and the triangular pattern refers to the amount data of Sun et al, 42 and in (b), the square pattern refers to Zhu et al's data, 46 while the triangular pattern refers to Yang et al 43 Figure 9. Relationship between TOC and porosity (a) and the specific surface area (b).…”

Section: Discussionmentioning

confidence: 95%

“…Relationship between TOC and porosity (a) and the specific surface area (b). Note: in (a), the diamond pattern refers to the data of Chen et al, 41 the dash refers to the data of Sun et al, 42 the triangle refers to the data of Yang et al, 43 and the square refers to the data of Nie et al, 45 and in (b), the diamond pattern refers to Chen et al, 41 the triangle refers to Yang et al, 44 and the square refers to Zhu et al 46 specific surface area correlation coefficient is 0.9. The reasons for the negative correlations may include the following:…”

Section: Discussionmentioning

confidence: 99%

“…Relationship between Ro and porosity (a) and specific surface area (b). Note: in (a), the diamond pattern refers to the data of Nie et al45 and the triangular pattern refers to the amount data of Sun et al,42 and in (b), the square pattern refers to Zhu et al's data,46 while the triangular pattern refers to Yang et al43…”

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Pore Characterization and Its Controlling Factors in the Wufeng-Longmaxi Shale of North Guizhou, Southwest China

Zhao

Tang

et al. 2020

Energy Fuels

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Pore types and structure in shales have a significant impact on shale gas accumulation and shale reservoir quality. Based on data from the Wufeng-Longmaxi formation, this paper presents an in-depth investigation of pore types and structure in shales, including a detailed analysis of pore features and controlling factors of pore development. During this study, the researchers used eight testing techniques, including scanning electron microscopy (SEM) after Ar-ion milling, total organic carbon (TOC), thermal maturity, thin-section identification, X-ray diffraction, mercury intrusion, pulse decay porosity and permeability, and low-temperature N2 adsorption. The study identified five types of reservoir spaces in Wufeng-Longmaxi shales, including organic pores, interparticle pores, intercrystalline pores, dissolved pores, and microfractures, among which organic pores and interparticle pores were the most common types. The test results suggested that the pore diameters were predominantly 5–20 nm and 5–10 μm. The findings also indicated that the pore throats were narrow and the pore connectivity was relatively good. The porosity and permeability were generally low, with the former measured at 1.27% on average and the latter at 0.0116 mD. The controlling factors of pore development in the Wufeng-Longmaxi shale were mainly thermal maturity, TOC, and mineral components. TOC had a positive correlation with the specific surface area. TOC was associated with samples with the lowest clay content, and the Brunauer–Emmett–Teller (BET) specific surface area was correlated with TOC content. The clay mineral content was negatively correlated with porosity, indicating a clear controlling role in pore development by TOC and clay mineral content. In addition, a favorable thermal maturity could contribute to the pore development in the study area.

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The main controlling factors on shale gas occurrence characteristics in deep and high-over mature shales: A case study of Silurian Longmaxi Formation in the Sichuan Basin, southern China

Pang

et al. 2022

Energy Reports

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Insight into the pore structure of Wufeng-Longmaxi black shales in the south Sichuan Basin, China

Cited by 18 publications

References 43 publications

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms

Pore Characterization and Its Controlling Factors in the Wufeng-Longmaxi Shale of North Guizhou, Southwest China

The main controlling factors on shale gas occurrence characteristics in deep and high-over mature shales: A case study of Silurian Longmaxi Formation in the Sichuan Basin, southern China

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Insight into the pore structure of Wufeng-Longmaxi black shales in the south Sichuan Basin, China

Cited by 18 publications

References 43 publications

Influence of Pore Structure on Shale Gas Recovery with CO2 Sequestration: Insight Into Molecular Mechanisms

Influence of Pore Structure on Shale Gas Recovery with CO2 Sequestration: Insight Into Molecular Mechanisms

Pore Characterization and Its Controlling Factors in the Wufeng-Longmaxi Shale of North Guizhou, Southwest China

The main controlling factors on shale gas occurrence characteristics in deep and high-over mature shales: A case study of Silurian Longmaxi Formation in the Sichuan Basin, southern China

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Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms