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 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.

scholarly journals Adsorption Characteristics and Controlling Factors of CH4 on Coal-Measure Shale, Hedong Coalfield

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 63
Author(s):  
Weidong Xie ◽  
Meng Wang ◽  
Hongyue Duan
Keyword(s):  
Organic Matter ◽  
Adsorption Capacity ◽  
Mineral Composition ◽  
Shale Gas ◽  
Total Content ◽  
Coal Measure ◽  
Gas Reservoirs ◽  
Quartz Content ◽  
Adsorption Characteristics ◽  
Adsorbed Gas

Adsorbed gas is one of the crucial occurrences in shale gas reservoirs; thus, it is of great significance to ascertain the adsorption capacity of shale and the adsorption characteristics of CH4. In this investigation, the Taiyuan–Shanxi Formations’ coal-measure shale gas reservoir of the Carboniferous–Permian era in the Hedong Coalfield was treated as the research target. Our results exhibit that the shale samples were characterized by a high total organic carbon (TOC) and over to high-over maturity, with an average TOC of 2.45% and average Ro of 2.59%. The mineral composition was dominated by clay (62% on average) and quartz (22.45% on average), and clay was mainly composed of kaolinite and illite. The Langmuir model showed a perfect fitting degree to the experimental data: VL was in the range of 0.01 cm3/g to 0.77 cm3/g and PL was in the range of 0.23–8.58 MPa. In addition, the fitting degree depicted a linear negative correlation versus TOC, while mineral composition did not exhibit a significant effect on the fitting degree, which was caused by the complex pore structure of organic matter, and the applicability of the monolayer adsorption theory was lower than that of CH4 adsorption on the mineral’s pore surface. An apparent linear positive correlation of VL versus the TOC value was recorded; furthermore, the normalized VL increased with the growth of the total content of clay mineral (TCCM), decreased with the growth of the total content of brittle mineral (TCBM), while there was no obvious correlation of normalized VL versus kaolinite, illite and quartz content. The huge amount of micropores and complex internal structure led to organic matter possessing a strong adsorption capacity for CH4, and clay minerals also promoted adsorption due to the development of interlayer pores and intergranular pores.

Investigation of the methane adsorption characteristics of marine organic-rich shale: A case study of the lower Cambrian Niutitang Shale in the Fenggang block, northern Guizhou Province, South China

2018 ◽  
Vol 6 (4) ◽  
pp. T819-T833 ◽  
Author(s):  
Yang Gu ◽  
Wenlong Ding ◽  
Min Yin ◽  
Ruyue Wang ◽  
Baocheng Jiao ◽  
...  
Keyword(s):  
Specific Surface ◽  
Pore Size ◽  
Adsorption Capacity ◽  
Surface Area ◽  
South China ◽  
Pore Volume ◽  
Lower Cambrian ◽  
Methane Adsorption ◽  
Guizhou Province ◽  
Average Value

The marine shale in South China has great gas exploration potential, and exploration in the Sichuan Basin has been successful, but the degree of exploration remains low in the Guizhou Province. We used organic geochemical analyses (total organic carbon content and kerogen type), scanning electron microscopy (SEM), field emission SEM, nuclear magnetic resonance (NMR), X-ray diffraction analysis, and low-temperature [Formula: see text] and [Formula: see text] adsorption experimental methods to study the micropore types and pore structures and their effects on the methane adsorption capacity of organic-rich shales found in the Fenggang block in northern Guizhou Province. The results indicate that the microscopic surface porosity of the lower Cambrian Niutitang Formation ranges from 2.88% to 5.34%, with an average value of 3.86%. Based on nitrogen adsorption methods, the range of the average pore size distribution is 4.6–9.491 nm, with an average value of 6.68 nm. All of the samples exhibit significant unimodal distributions. The main pore size is less than 10 nm, and these pores account for most of the mesopore volume, which is generally consistent with the NMR results. The methane adsorption capacity of the shale samples gradually increases in the range of 0–8 MPa at 30°C and reaches a maximum at approximately 10 MPa. Positive correlations were found between the gas content and specific surface area, total pore volume, and micropore volume. These strong correlations indicate that the Niutitang Shale has a high specific surface area, a high pore volume, and narrow-diameter pores, demonstrating that it has a high gas adsorption capacity. The results of this study provide valuable information regarding the adsorption characteristics of marine shales and the factors that affect those characteristics.

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.

Pore structure characteristics and its effect on adsorption capacity of Niutitang marine shale in Sangzhi block, southern China

2019 ◽  
Vol 7 (4) ◽  
pp. T843-T856
Author(s):  
Xinghua Wang ◽  
Arash Dahi Taleghani ◽  
Wenlong Ding
Keyword(s):  
Organic Matter ◽  
Pore Structure ◽  
Adsorption Capacity ◽  
Southern China ◽  
Quartz Content ◽  
Isothermal Adsorption ◽  
Structure Characteristics ◽  
Marine Shale ◽  
Lp Formula ◽  
Organic Pores

Characteristics of shale pore structures may play an important role in natural gas accumulation and consequently estimating the original gas in place. To determine the pore structure characteristics of Niutitang marine shale in the Sangzhi block, we carried out [Formula: see text] adsorption-desorption (LP-[Formula: see text]GA), [Formula: see text] adsorption (LP-[Formula: see text]GA), and methane isothermal adsorption on shale samples to reveal the pore size distribution (PSD) and its impact on the adsorption capacity. Results indicate that the Niutitang Shale is in stages of maturity and overmaturity with good organic matter, and they also indicate well-developed interparticle, intraparticle, and organic pores. Quartz and clay are found to be the main minerals, and the high illite content means that the Niutitang Shale is experiencing the later stage of clay mineral transformation. Various-sized shale pores are well-developed, and most of them are narrow and slit-like. For pores with diameters of 2–300 nm measured with LP-[Formula: see text]GA, mesopores (2–50 nm) contribute most of the total specific surface area (SSA) and total pore volume (TPV) in comparison to macropores (50–300 nm). For micropores ([Formula: see text]) tested by LP-[Formula: see text]GA, the PSD appears to be multimodal; shale pores of 0.50–0.90 nm diameter contribute most of the SSA and TPV. [Formula: see text]-SSA and [Formula: see text]-SSA indicate positive correlations with their corresponding TPV. The total organic matter (TOC) has good correlation with the SSA and TPV of micropores. The Langmuir volume positively correlates with the total SSA. Additionally, the TOC content has a good correlation with the Langmuir volume, which is consistent with the observation of well-developed fossils of diatoms and organic pores. As an important source of organic matter, more diatoms mean more organic matter, larger TOC values and quartz content, larger SSA and TPV of micropores, and, of course, stronger shale adsorption capacity. The results provide important guidance for the exploration and development of shale gas existing in the Sangzhi block.

FRACTAL CHARACTERISTICS OF NANOSCALE PORES IN SHALE AND ITS IMPLICATIONS ON METHANE ADSORPTION CAPACITY

Fractals ◽  
2019 ◽  
Vol 27 (01) ◽  
pp. 1940014 ◽  
Author(s):  
YU LIU ◽  
YANMING ZHU ◽  
YANG WANG ◽  
SHANGBIN CHEN
Keyword(s):  
Adsorption Capacity ◽  
Rough Surface ◽  
Large Scale ◽  
Fractal Theory ◽  
Fractal Dimensions ◽  
Methane Adsorption ◽  
Small Scale ◽  
Sem Images ◽  
Fractal Characteristics ◽  
Organic Pores

Pore structure in shale controls the gas storage mechanism and gas transport behaviors. Since nanoscale pores in shale matrix have fractal characteristics, fractal theory can be used to study its structure. In addition, fractal method has its own advantages to investigate nanopores in shale, especially for the heterogeneity and irregularity of nanopores in shale. In this work, fractal features of nanoscale pores and the implication on methane adsorption capacity of shale were investigated by employing low pressure nitrogen adsorption, scanning electron microscopy (SEM), and methane adsorption experiments. Frenkel–Halsey–Hill (FHH) model was also used to calculate the fractal parameters of nanoscale pores in shale. The results showed that nanoscale pores in 12 shale samples have obvious fractal features. All the fractal curves of these shale samples can be divided into two segments, which are cut off by [Formula: see text], and the fractal dimensions of these two segments vary from 2.48 to 2.92 [Formula: see text] and 2.42 to 2.80 [Formula: see text], respectively. Based on SEM images, it is found that self-similarity of organic pore systems in shales refers to two aspects. One is that relatively large-scale and small-scale pores have similar formation properties and types, which are of elliptical shape with rough surface. The other is that some small-scale pores are formed by rough surface of relatively large pores. The results also demonstrate that methane adsorption capacity of shale samples increase with increasing total organic carbon (TOC) contents. This is mainly because organic matter is rich in pores and has relatively large fractal dimension values. Larger fractal dimensions indicate rougher pore surfaces and could form more small-scale organic pores. These organic pores would provide more space for methane adsorption.

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

Characterization of Pore Structure and Its Relationship with Methane Adsorption on Medium-High Volatile Bituminous Coal: An Experimental Study Using Nuclear Magnetic Resonance

2021 ◽  
Vol 21 (1) ◽  
pp. 515-528
Author(s):  
Baoxin Zhang ◽  
Xuehai Fu ◽  
Ze Deng ◽  
Ming Hao
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Adsorption Capacity ◽  
Size Distribution ◽  
Bituminous Coal ◽  
Methane Adsorption ◽  
Nuclear Magnetic

A number of studies have used the nuclear magnetic resonance (NMR) technique to analyse pore characteristics and to discuss the influencing mechanisms of pore structure on methane adsorption. However, there are few studies on the dynamic characteristics of methane adsorption over time under the same temperature and pressure conditions, especially by using the cylindrical coal samples. In this study, scanning electron microscopy (SEM), mercury injection porosimetry (MIP), isothermal adsorption and NMR techniques were carried out on the four medium-high volatile bituminous coal samples from Shanxi Province, China. The simulation of methane adsorption was carried out with the custom adsorption instruments. Based on the experimental results and the Hodot pore size classification standard, the pore size distribution of the samples was analysed. In addition, the influence of nanopore structure and water content on methane adsorption was discussed. The results show that the T2 relaxation diagram of the four coal samples has a bimodal-triple peak, which reflects the complexity of the pore structure. Due to the clay minerals filling microfractures in the sample HX, the connectivity of the nanopores is reduced, in addition there is an obvious gap between the peaks in the relaxation diagram. After calculation of the T2 relaxation diagrams of the coals, the results can be converted into the pore size distribution map. The pores in the four samples are mainly composed of the macropores, followed by the mesopores, and the ratio of micropores and transition pores is relatively small. At Sw (saturated in 5% brine for 24 h) and Sir (dried at 333 K for 3 h) conditions, the adsorption capacity of the four samples presented a positive correlation with the effective porosity and the ratio of micropores, and presented a negative correlation with the ratio of mesopores, while the macropores contribute less to the adsorption. Compared with samples at Sw conditions, the adsorption capacity of the samples at Sir conditions shows an overall increasing trend, which is approximately 1.6 times that of the samples at Sw conditions on average. When a large amount of liquid water invades the nanopores and fractures, the water occupies the adsorption space of the methane due to the wettability effects and capillary pressure, which reduces the adsorption capacity.

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