scholarly journals Influence of black shale composition on methane adsorption and gas content: Implications for gas storage in the Longmaxi black shales

2018 ◽  
Vol 22 (1) ◽  
pp. 59-63 ◽  
Author(s):  
Haihua Zhu ◽  
Tingshan Zhang ◽  
Jun Lang ◽  
Jianli Zeng ◽  
Xing Liang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Adsorption Capacity ◽  
Methane Adsorption ◽  
Black Shales ◽  
Gas Content ◽  
Gas Generation ◽  
Langmuir Adsorption ◽  
Longmaxi Shale ◽  
Scatter Plots ◽  
Shale Composition

The influence of shale composition on methane adsorption capability and gas content is investigated using 14 samples from Well YS8 in the southern Sichuan Basin, China. The results show that the Langmuir adsorption capacity of the Longmaxi shale is mainly a function of the total organic carbon (TOC) content. When TOC is ~1.1%, 50% CH4 is adsorbed onto the surface of the organic matter. The mineral content has limited control on the adsorption capacity of the Longmaxi shales. Organic matter is also a major control on gas content when TOC content is <1.0%. When TOC is >1.0%, gas content remains constant, indicating that gas preservation is more important than gas generation and rock adsorption capacity. Scatter plots of TOC versus gas content and, Langmuir adsorption capacity shows that when TOC is <2.0%, CH4 occurs both as free and absorbed gas, and CH4 occurs mainly as absorbed gas when TOC is >2.0%.

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 Simulation of methane adsorption in diverse organic pores in shale reservoirs with multi-period geological evolution

2021 ◽  
Author(s):  
Shangbin Chen ◽  
Chu Zhang ◽  
Xueyuan Li ◽  
Yingkun Zhang ◽  
Xiaoqi Wang
Keyword(s):  
Organic Matter ◽  
Pore Size ◽  
Adsorption Capacity ◽  
Thermal Evolution ◽  
Methane Adsorption ◽  
Storage Site ◽  
Pressure Sensitivity ◽  
Adsorption Characteristics ◽  
Shale Reservoirs ◽  
Organic Pores

AbstractIn shale reservoirs, the organic pores with various structures formed during the thermal evolution of organic matter are the main storage site for adsorbed methane. However, in the process of thermal evolution, the adsorption characteristics of methane in multi type and multi-scale organic matter pores have not been sufficiently studied. In this study, the molecular simulation method was used to study the adsorption characteristics of methane based on the geological conditions of Longmaxi Formation shale reservoir in Sichuan Basin, China. The results show that the characteristics of pore structure will affect the methane adsorption characteristics. The adsorption capacity of slit-pores for methane is much higher than that of cylindrical pores. The groove space inside the pore will change the density distribution of methane molecules in the pore, greatly improve the adsorption capacity of the pore, and increase the pressure sensitivity of the adsorption process. Although the variation of methane adsorption characteristics of different shapes is not consistent with pore size, all pores have the strongest methane adsorption capacity when the pore size is about 2 nm. In addition, the changes of temperature and pressure during the thermal evolution are also important factors to control the methane adsorption characteristics. The pore adsorption capacity first increases and then decreases with the increase of pressure, and increases with the increase of temperature. In the early stage of thermal evolution, pore adsorption capacity is strong and pressure sensitivity is weak; while in the late stage, it is on the contrary.

scholarly journals Nanostructure Effect on Methane Adsorption Capacity of Shale with Type III Kerogen

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1690
Author(s):  
Yong Han ◽  
Yanming Zhu ◽  
Yu Liu ◽  
Yang Wang ◽  
Han Zhang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Adsorption Capacity ◽  
Clay Minerals ◽  
Co2 Adsorption ◽  
Methane Adsorption ◽  
Experimental Results ◽  
Type Iii ◽  
Positive Effects ◽  
Inorganic Matter ◽  
Injection Experiment

This study focuses on the nanostructure of shale samples with type III kerogen and its effect on methane adsorption capacity. The composition, pore size distribution, and methane adsorption capacities of 12 shale samples were analyzed by using the high-pressure mercury injection experiment, low-temperature N2/CO2 adsorption experiments, and the isothermal methane adsorption experiment. The results show that the total organic carbon (TOC) content of the 12 shale samples ranges from 0.70% to ~35.84%. In shales with type III kerogen, clay minerals and organic matter tend to be deposited simultaneously. When the TOC content is higher than 10%, the clay minerals in these shale samples contribute more than 70% of the total inorganic matter. The CO2 adsorption experimental results show that micropores in shales with type III kerogen are mainly formed in organic matter. However, mesopores and macropores are significantly affected by the contents of clay minerals and quartz. The methane isothermal capacity experimental results show that the Langmuir volume, indicating the maximum methane adsorption capacity, of all the shale samples is between 0.78 cm3/g and 9.26 cm3/g. Moreover, methane is mainly adsorbed in micropores and developed in organic matter, whereas the influence of mesopores and macropores on the methane adsorption capacity of shale with type III kerogen is small. At different stages, the influencing factors of methane adsorption capacity are different. When the TOC content is <1.4% or >4.5%, the methane adsorption capacity is positively correlated with the TOC content. When the TOC content is in the range of 1.4–4.5%, clay minerals have obviously positive effects on the methane adsorption capacity.

scholarly journals Mineral compositional controls on the porosity of black shales from the Wufeng and Longmaxi Formations (Southern Sichuan Basin and its surroundings) and insights into shale diagenesis

2018 ◽  
Vol 36 (4) ◽  
pp. 665-685
Author(s):  
Mei Han ◽  
Chao Han ◽  
Zuozhen Han ◽  
Zhigang Song ◽  
Wenjian Zhong ◽  
...  
Keyword(s):  
Organic Matter ◽  
Pore Size ◽  
Pore Volume ◽  
Total Pore Volume ◽  
Black Shales ◽  
Carbonate Content ◽  
Pore Sizes ◽  
Pore Size Distributions ◽  
Shale Composition ◽  
The Relationship

The effects of brittle minerals in shale diagenesis on shale pores remain controversial and it is difficult to quantify directly. However, the relationship between brittle minerals and shale pores could provide indirect guidance regarding diagenesis processes in post-mature marine shales. In this study, the pore size distribution was determined, and the relationship between pore volume and shale composition was examined in shale samples with different total organic carbon contents from the Wufeng and Longmaxi Formations, with the objective of distinguishing pore size ranges in organic matter and inorganic minerals, respectively, and studying shale diagenesis. The samples of the Wufeng and Longmaxi shales are composed of clay minerals, calcite, dolomite, quartz, feldspar, and some minor components. The pore size distributions, which were determined using nitrogen adsorption isotherm analysis of shale and kerogen, show similar trends for pore sizes less than approx. 6.5 nm but different trends for larger pore sizes. Mercury injection saturation shows that macropores account for 14.4–22% of the total pore volume. Based on a series of crossplots describing the relationships between shale composition and pore volume or porosity associated with different pore sizes as well as on scanning electron microscopy observations, organic matter pores were found to comprise most of the micro-mesopores (pore diameters < 6.5 nm). Organic matter pores and intraparticle pores associated with carbonate constitute the majority of mesopores (pore diameters 6.5–50 nm). Finally, interparticle pores associated with quartz comprise the majority of the macropores. The mesopores associated with carbonate were formed by dissolution during diagenesis, whereas the macropores associated with quartz are the remainders of the original interparticle pores. Mesopore volumes increase with increasing carbonate content while macropore volumes decrease due to the ‘pore size controlled solubility’ effect, which causes dissolved calcium carbonate to precipitate in larger macropores.

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.

Effects of pore structure and wettability on methane adsorption capacity of mud rock: Insights from mixture of organic matter and clay minerals

Fuel ◽  
2019 ◽  
Vol 251 ◽  
pp. 551-561 ◽  
Author(s):  
Peng Luo ◽  
Ningning Zhong ◽  
Imran Khan ◽  
Xiaomei Wang ◽  
Huajin Wang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Pore Structure ◽  
Adsorption Capacity ◽  
Clay Minerals ◽  
Methane Adsorption

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.

Effect of Organic Matter and Thermal Maturity on Methane Adsorption Capacity on Shales from the Middle Magdalena Valley Basin in Colombia

2017 ◽  
Vol 31 (11) ◽  
pp. 11698-11709 ◽  
Author(s):  
Olga Patricia Ortiz Cancino ◽  
Deneb Peredo Mancilla ◽  
Manuel Pozo ◽  
Edgar Pérez ◽  
David Bessieres
Keyword(s):  
Organic Matter ◽  
Adsorption Capacity ◽  
Methane Adsorption ◽  
Thermal Maturity

scholarly journals Effect of Pre-Adsorbed Water on Methane Adsorption Capacity in Shale-Gas Systems

2021 ◽  
Vol 9 ◽  
Author(s):  
Lei Chen ◽  
Zhenxue Jiang ◽  
Shu Jiang ◽  
Song Guo ◽  
Jingqiang Tan
Keyword(s):  
Relative Humidity ◽  
Adsorption Capacity ◽  
Shale Gas ◽  
Evaluation Method ◽  
Gas Adsorption ◽  
Water Saturation ◽  
Adsorbed Water ◽  
Lower Jurassic ◽  
Methane Adsorption ◽  
Gas Content

The presence and content of water will certainly affect the gas adsorption capacity of shale and the evaluation of shale gas content. In order to reasonably evaluate the gas adsorption capacity of shale under actual reservoir conditions, the effect of water on methane adsorption capacity needs to be investigated. Taking the Da’anzhai Member of the Lower Jurassic Ziliujing Formation in the northeastern Sichuan Basin, China as an example, this study attempts to reveal the effect of pre-adsorbed water on methane adsorption capacity in shale-gas systems by conducting methane adsorption experiments in two sequences, firstly at different temperatures under dry condition and secondly at different relative humidity levels under the same temperature. The results show that temperature and relative humidity (i.e., water saturation) are the main factors affecting the methane adsorption capacity of shale for a single sample. The key findings of this study include: 1) Methane adsorption capacity of shale first increases then decreases with depth, reaching a peak at about 1,600–2,400 m. 2) Lower relative humidity correlates to greater maximum methane adsorption capacity and greater depth to reach the maximum methane adsorption capacity. 3) 20% increase of relative humidity results in roughly 10% reduction of maximum methane adsorption capacity. As a conclusion, methane adsorption capacity of shale is predominately affected by water saturation, pore type and pore size of shale. This study could provide a theoretical basis for the establishment of a reasonable evaluation method for shale adsorbed gas content.

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