Methane Adsorption Capacity Reduction Process of Water-Bearing Shale Samples and Its Influencing Factors: One Example of Silurian Longmaxi Formation Shale from the Southern Sichuan Basin in China

2021 ◽  
Author(s):  
Zhiye Gao ◽  
Shuling Xiong
Keyword(s):  
Adsorption Capacity ◽  
Influencing Factors ◽  
Sichuan Basin ◽  
Reduction Process ◽  
Methane Adsorption ◽  
Longmaxi Formation ◽  
Capacity Reduction

Factors affecting the nanopore structure and methane adsorption capacity of organic-rich marine shales in Zhaotong area, Southern Sichuan Basin

2020 ◽  
Vol 8 (2) ◽  
pp. T403-T419
Author(s):  
Panke Sun ◽  
Hanqing Zhu ◽  
Huaimin Xu ◽  
Xiaoni Hu ◽  
Linfeng Tian
Keyword(s):  
Adsorption Capacity ◽  
Sichuan Basin ◽  
Clay Content ◽  
Mineralogical Composition ◽  
Methane Adsorption ◽  
Gas Content ◽  
Quartz Content ◽  
Structure Characteristics ◽  
Longmaxi Shale ◽  
Nanopore Structure

As a national shale-gas demonstration zone in China, the Zhaotong area has great gas resource potential. However, the nanopore structure characteristics, methane adsorption capacity, and their affecting factors of the Lower Silurian Longmaxi Shale in this area remain unclear. To address these puzzles, we conducted a series of experiments, such as X-ray diffraction, field emission scanning electron microscopy, low-pressure [Formula: see text] adsorption, and high-pressure methane adsorption, and we calculated the relevant characteristic parameters, such as pore volume (PV), specific surface area (SSA), fractal dimension, and Langmuir parameters by using the nonlocal density functional theory method, Frenkel-Halsey-Hill theory, and Langmuir model, respectively. The results indicate that the nanopores of the Lower Longmaxi Shale in the Zhaotong area are composed of micropores and mesopores, which mainly exist as organic matter (OM) pores. The pore surface exhibits a high degree of heterogeneity as indicated by the fractal dimensions ranging from 2.845 to 2.866. The nanopore structure characteristics (i.e., SSA and PV) and methane adsorption capacity are mainly controlled by the total organic carbon (TOC) content. In addition, the mineralogical composition (i.e., the quartz and clay content) also contributes significantly to the micropore PV and gas content. The external provenance has a significant effect on the mineralogical composition, TOC content, and methane adsorption capacity. With the increasing influence of the external provenance, the biogenic quartz content decreases and the relationship between the quartz content and TOC content becomes more discrete, which indicates the change of depositional environment, and the clay content increases, which can dilute the OM concentration during the deposition and enhance the compaction potential, and it can eventually result in less gas content. The results of this study reveal the nanopore system characteristics of the Longmaxi Shale in the Zhaotong area and provide further insight into the influence of external provenance on reservoir characteristics and gas content variability of the Lower Longmaxi Shale in the southern Sichuan Basin.

scholarly journals Characteristics and Origin of Methane Adsorption Capacity of Marine, Transitional, and Lacustrine Shales in Sichuan Basin, China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Xianglu Tang ◽  
Wei Wu ◽  
Guanghai Zhong ◽  
Zhenxue Jiang ◽  
Shijie He ◽  
...  
Keyword(s):  
Organic Matter ◽  
Water Content ◽  
Adsorption Capacity ◽  
Clay Minerals ◽  
Shale Gas ◽  
Sichuan Basin ◽  
Thermal Evolution ◽  
Methane Adsorption ◽  
Isothermal Adsorption ◽  
Xujiahe Formation

Adsorbed gas is an important component of shale gas. The methane adsorption capacity of shale determines the composition of shale gas. In this study, the methane adsorption capacity of marine, transitional, and lacustrine shales in the Sichuan Basin was analyzed through its isothermal adsorption, mineral composition, water content, etc. The results show that the methane adsorption capacity of marine (Qiongzhusi Formation and Longmaxi Formation), transitional (Longtan Formation), and lacustrine (Xujiahe Formation and Ziliujing Formation) shales is significantly different. The Longtan Formation has the strongest methane adsorption capacity. This is primarily related to its high organic matter and organic matter type III content. The methane adsorption capacity of the lacustrine shale was the weakest. This is primarily related to the low thermal evolution degree and the high content of water-bearing clay minerals. Smectite has the highest methane adsorption capacity of the clay minerals, due to its crystal structure. The water content has a significant effect on methane adsorption largely because water molecules occupy the adsorption site. Additionally, the temperature and pressure in a specific range significantly affect methane adsorption capacity.

INVESTIGATION OF FRACTAL CHARACTERISTICS AND METHANE ADSORPTION CAPACITY OF THE UPPER TRIASSIC LACUSTRINE SHALE IN THE SICHUAN BASIN, SOUTHWEST CHINA

Fractals ◽  
2019 ◽  
Vol 27 (01) ◽  
pp. 1940011 ◽  
Author(s):  
LEI CHEN ◽  
ZHENXUE JIANG ◽  
KEYU LIU ◽  
WEI YANG ◽  
SHU JIANG ◽  
...  
Keyword(s):  
Pore Structure ◽  
Adsorption Capacity ◽  
Sichuan Basin ◽  
Southwest China ◽  
Upper Triassic ◽  
Methane Adsorption ◽  
Relative Pressure ◽  
Pore Surface ◽  
Fractal Characteristics ◽  
The Sichuan Basin

To better understand the nanopore characteristics and their effects on methane adsorption capacity of shales, we performed fractal analysis of nine shale samples collected from the fifth member of Upper Triassic Xujiahe Formation in the Sichuan Basin, southwest China. [Formula: see text] adsorption results show that shales have different adsorption characteristics at relative pressure of 0–0.5 and 0.5–1. Two fractal dimensions [Formula: see text] and [Formula: see text] were calculated using the Frenkel–Halsey–Hill (FHH) equation. Results show that the methane adsorption capacity increases with the increase of [Formula: see text] and [Formula: see text], of which [Formula: see text] has a more significant influence on adsorption capacity than [Formula: see text]. Further studies indicate that [Formula: see text] represents the pore surface fractal characteristics caused by the irregularity of shale surface, whereas [Formula: see text] represents the pore structure fractal characteristics, which is mainly affected by shale components (e.g. TOC, clay minerals) and pore parameters (e.g. average pore diameter, micropores content). A higher [Formula: see text] corresponds to a more irregular pore surface, which provides more space for methane adsorption. While a higher [Formula: see text] indicates a more complex pore structure and a stronger capillary condensation action on the pore surface, which in turn enhances the methane adsorption capacity.

scholarly journals Univariate and Multivariate Analyses of Influencing Factors on Methane Adsorption Capacity of Semianthracite

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Shihui Hou ◽  
Xiaoming Wang ◽  
Yudong Yuan ◽  
Sidong Pan ◽  
Zheng Dang ◽  
...  
Keyword(s):  
Specific Surface ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Influencing Factors ◽  
Specific Surface Area ◽  
Multivariate Analyses ◽  
Methane Adsorption ◽  
Coal Rank ◽  
Strong Positive Correlation ◽  
Quantification Theory

Methane adsorption isotherm experiments on semianthracite (2.00-2.33% R o , max ) collected from the Xin’an coal mine, Henan Province, China, were conducted to investigate the effects of pore structure, coal quality, coal maceral, and coal rank on methane adsorption capacity with applications of univariate and multivariate analyses. Methane adsorption capacity varies significantly from 12.03 to 28.40 cm3/g. In univariate analysis, methane adsorption capacity has a strong positive correlation with pore specific surface area, weak positive correlations with pore volume and ash content, and weak negative correlations with moisture content and inertinite content. No correlation is observed between methane adsorption capacity and coal rank. In multivariate analysis, the mathematical model of methane adsorption capacity affected by the combined individual variables is established based on quantification theory I. There are similarities and differences between the two analyses. The similarities are that pore specific surface area has the greatest contribution to methane adsorption capacity, while coal rank has the least contribution. The differences are reflected in two aspects. Firstly, the other influencing factors contribute differently to methane adsorption capacity. Secondly, the positive or negative correlations of some influencing factors present the opposite. The mathematic model synthetically covers the combined effects of the influencing factors, which is more representative in evaluating methane adsorption capacity.

Investigation of Supercritical Methane Adsorption of Overmature Shale in Wufeng-Longmaxi Formation, Southern Sichuan Basin, China

2019 ◽  
Vol 33 (3) ◽  
pp. 2078-2089 ◽  
Author(s):  
Yang Wang ◽  
Luofu Liu ◽  
Yue Sheng ◽  
Ximeng Wang ◽  
Shanshan Zheng ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Methane Adsorption ◽  
Longmaxi Formation

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

2018 ◽  
Vol 37 (1) ◽  
pp. 60-82 ◽  
Author(s):  
Sheng Zhao ◽  
Longyi Shao ◽  
Haihai Hou ◽  
Yue Tang ◽  
Zhen Li ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Influencing Factors ◽  
Coalbed Methane ◽  
Vitrinite Reflectance ◽  
Negative Relationship ◽  
Methane Adsorption ◽  
High Rank ◽  
Gas Content ◽  
Coal Rank ◽  
Adsorption Characteristics

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.

A composition-based model for methane adsorption of overmature shales in Wufeng and Longmaxi Formation, Sichuan Basin

2021 ◽  
pp. 130766
Author(s):  
Wenbin Jiang ◽  
Gaohui Cao ◽  
Chao Luo ◽  
Mian Lin ◽  
Lili Ji ◽  
...  
Keyword(s):  
Sichuan Basin ◽  
Methane Adsorption ◽  
Longmaxi Formation
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