Quantitative Characterization for the Micronanopore Structures of Terrestrial Shales with Different Lithofacies Types: A Case Study of the Jurassic Lianggaoshan Formation in the Southeastern Sichuan Basin of the Yangtze Region

Due to the specificity of the geological background, terrestrial strata are widely distributed in the major hydrocarbon-bearing basins in China. In addition, terrestrial shales are generally featured with high thickness, multiple layers, high TOC content, ideal organic matter types, and moderate thermal evolution, laying a solid material foundation for hydrocarbon generation. However, the quantitative characterization study on their pore structure remains inadequate. In this study, core samples were selected from the Middle Jurassic Lianggaoshan Formation in the southeastern Sichuan Basin of the Upper Yangtze Region for analyses on its TOC content and mineral composition. Besides, experiments including oil washing, the adsorption/desorption of CO2 and nitrogen, and high-pressure mercury pressure experiments were carried out. The pore structure of different petrographic types of terrestrial shales can be accurately and quantitatively characterized with these works. The following conclusions were drawn: for organic-rich mixed shales and organic-rich clay shales, the TOC content is the highest; the pore volume, which is primarily provided by macropores and specific surface area, which is provided by mesopores, was the largest, thus providing more space for shale oil and gas reservation. The pores take on a shape either close to a parallel plate slit or close to or of an ink bottle. For organic-matter-bearing shales, both the pore volume and specific surface area are the second-largest and are provided by the same sized pores with organic-rich mixed shales. Its pores take on a shape approximating either a parallel plate slit or an ink bottle. Organic-matter-bearing mixed shales have the lowest pore volume and specific surface area; its pore volume is primarily provided by macropores, and the specific surface area by mesopores and the shape of the pores are close to an ink bottle.

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Investigation of pore structure characteristics of marine organic-rich shales using low-pressure N2 adsorption experiments and fractal theory

Interpretation ◽

10.1190/int-2018-0191.1 ◽

2019 ◽

Vol 7 (3) ◽

pp. T671-T685

Author(s):

Difei Zhao ◽

Shuai Yin ◽

Yinghai Guo ◽

Chengyao Ren ◽

Ruyue Wang ◽

...

Keyword(s):

Organic Matter ◽

Specific Surface ◽

Pore Structure ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Southern China ◽

Fractal Theory ◽

Low Pressure ◽

Fractal Characteristics

The pore structure and fractal characteristics of the Lower Cambrian marine organic-rich shale in southern China were comprehensively studied using low-pressure [Formula: see text] adsorption and organic geochemical experiments, X-ray diffraction, petrophysical property tests, and scanning electron microscope observations. The results indicate that the total organic carbon (TOC) content of the study shale varies between 0.45% and 8.50%, with an average value of 3.97%. The adsorption isotherm of the shale samples belongs to type IV, and slit-type pores are the predominant pore type in these shales. The shale has a Brunner–Emmet–Teller specific surface area ranging from 1.83 to [Formula: see text], a pore volume ranging from 0.00398 to [Formula: see text], and an average pore diameter ranging from 3.61 to 15.19 nm. Organic matter pores (OMPs) are the main contributors to the specific surface area and the pore volume. The organic matter is closely symbiotic with the epigenetic quartz. We have obtained two fractal dimensions ([Formula: see text] and [Formula: see text]) of the shale using the Frenkel-Halsey-Hill method. It was found that [Formula: see text] is suitable for the quantitative characterizing of the pore structure of nanopores inside the shale due to its good correlation with the TOC content and pore structure parameters. When the TOC content of the shale exceeds 4%, the main pore type inside the shale is OMP and the [Formula: see text] value mainly reflects the fractal characteristics of OMP. Moreover, we analyzed the seepage characteristics of different types of pores. It was found that the parallel plate-like pores and the slit-type pores are more favorable for fluid seepage than the ink bottle-like pores. The shale with [Formula: see text] and [Formula: see text] type pore structures should be the key exploration targets for the target shale in the study area.

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Nanometer Pore Structure Characterization of Taiyuan Formation Shale in the Lin-Xing Area Based on Nitrogen Adsorption Experiments

Minerals ◽

10.3390/min11030298 ◽

2021 ◽

Vol 11 (3) ◽

pp. 298

Author(s):

Chenlong Ding ◽

Jinxian He ◽

Hongchen Wu ◽

Xiaoli Zhang

Keyword(s):

Specific Surface ◽

Pore Structure ◽

Surface Area ◽

Specific Surface Area ◽

Shale Gas ◽

Pore Volume ◽

Ordos Basin ◽

Total Pore Volume ◽

Nitrogen Adsorption ◽

Taiyuan Formation

Ordos Basin is an important continental shale gas exploration site in China. The micropore structure of the shale reservoir is of great importance for shale gas evaluation. The Taiyuan Formation of the lower Permian is the main exploration interval for this area. To examine the nanometer pore structures in the Taiyuan Formation shale reservoirs in the Lin-Xing area, Northern Shaanxi, the microscopic pore structure characteristics were analyzed via nitrogen adsorption experiments. The pore structure parameters, such as specific surface area, pore volume, and aperture distribution, of shale were calculated; the significance of the pore structure for shale gas storage was analyzed; and the main controlling factors of pore development were assessed. The results indicated the surface area and hole volume of the shale sample to be 0.141–2.188 m2/g and 0.001398–0.008718 cm3/g, respectively. According to the IUPAC (International Union of Pure and Applied Chemistry) classification, mesopores and macropores were dominant in the pore structure, with the presence of a certain number of micropores. The adsorption curves were similar to the standard IV (a)-type isotherm line, and the hysteresis loop type was mainly similar to H3 and H4 types, indicating that most pores are dominated by open type pores, such as parallel plate-shaped pores and wedge-shaped slit pores. The micropores and mesopores provide the vast majority of the specific surface area, functioning as the main area for the adsorption of gas in the shale. The mesopores and macropores provide the vast majority of the pore volume, functioning as the main storage areas for the gas in the shale. Total organic carbon had no notable linear correlation with the total pore volume and the specific surface area. Vitrinite reflectance (Ro) had no notable correlation with the specific surface area, but did have a low “U” curve correlation with the total pore volume. There was no relationship between the quartz content and specific surface area and total pore volume. In addition, there was no notable correlation between the clay mineral content and total specific surface area and total pore volume.

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Effect of peat mire evolution on pore structure characteristics in thick coal seam: Examples from Xishanyao Formation (Middle Jurassic), Yili Basin, China

Energy Exploration & Exploitation ◽

10.1177/0144598720950479 ◽

2020 ◽

Vol 38 (5) ◽

pp. 1484-1514 ◽

Cited By ~ 1

Author(s):

Rongfang Qin ◽

Anmin Wang ◽

Daiyong Cao ◽

Yingchun Wei ◽

Liqi Ding ◽

...

Keyword(s):

Fractal Dimension ◽

Coal Seam ◽

Specific Surface ◽

Pore Structure ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Thick Coal Seam ◽

Structure Characteristics ◽

Cyclic Changes

The physical properties of thick coal seams show strong vertical heterogeneity; thus, an accurate characterization of their pore structure is essential for coalbed methane (CBM) exploration and production. A total of 18 coal samples, collected from a thick coal seam in the Yili Basin of NW China, were tested by a series of laboratory experiments to investigate the peat mire evolution and pore structure characteristics. The results show that the No. 4 coal seam has undergone multiple stages of evolution in the peatification stage, and was divided into four water-transgression/water-regression cycles according to the regular cyclic changes of the vitrinite/inertinite ratio, structure preservation index, gelification index, vegetation index, trace element ratios, and stable carbon isotopes of organic matter. The changes of pore structure characteristics with the changes of coal deposition cycles are also analyzed. It is concluded that pore structure characteristics of the four cycles are quite different. In each water-transgression cycle, the vitrinite gradually increased and the inertinite gradually decreased, resulting in a decrease of the porosity, pore volume, specific surface area, and fractal dimension. While in each water-regression cycle, the vitrinite gradually decreased and the inertinite gradually increased, leading to an increase of the porosity, pore volume, specific surface area, and fractal dimension. A strong relationship exists between the porosity, pore volume, specific surface area, fractal dimension, and submacerals, with fusinite and semifusinite which contained more pores having a positive correlation, desmocollinite and corpovitrinite which contained few pores having a negative correlation.

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Effects of extraction process on the dried cell wall pore structure of messmate heartwood

BioResources ◽

10.15376/biores.16.3.6074-6082 ◽

2021 ◽

Vol 16 (3) ◽

pp. 6074-6082

Author(s):

Weikai Wang ◽

Minghan Li ◽

Jiabin Cai

Keyword(s):

Cell Wall ◽

Specific Surface ◽

Pore Structure ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Gas Adsorption ◽

Extraction Process ◽

Micropore Volume ◽

Adsorption Method

In order to study the effects of a messmate heartwood extraction process on its cell wall pore structure and its drying ability, its nanopore structure was explored after via gas adsorption technology. Specifically, the messmate heartwood particles were extracted with methanol, and then the cell wall pore structure of the original and extracted samples were evaluated by N2 and CO2 sorption and pycnometer methods, respectively. Overall, compared with the original samples, the cell wall porosity, micropore volume, mesopore volume, BET specific surface area, and specific surface area of the micropores of the extracted messmate heartwoods increased by 2.55%, 0.007 cm3/g, 0.0014 cm3/g, 0.24 m2·g-1, and 21.9 m2·g-1, respectively. The cell wall pore volume measured via the gas adsorption method was smaller than the measurement from the pycnometer method. The results indicated that the presence of extractives made the messmate cell wall have a decreased pore volume and porosity, which may be one of the reasons messmate wood is difficult to dry. Messmate extractives primarily were present in the micropores of the cell wall in the range of 0.4 nm to 0.7 nm. However, gas sorption technology could not detect all the pores in the cell wall of the messmate heartwood sample.

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The influence factors for gas adsorption with different ranks of coals

Adsorption Science & Technology ◽

10.1177/0263617417730186 ◽

2017 ◽

Vol 36 (3-4) ◽

pp. 904-918 ◽

Cited By ~ 6

Author(s):

Deyong Guo ◽

Xiaojie Guo

Keyword(s):

Moisture Content ◽

Specific Surface ◽

Pore Structure ◽

Adsorption Capacity ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Gas Adsorption ◽

Total Pore Volume ◽

Factors Influencing

In this paper, scanning electron microscopy, low-temperature N2 adsorption and CH4 isothermal adsorption experiments were performed on 11 coal samples with Ro,max between 0.98 and 3.07%. The pore structure characteristics of coals (specific surface area, total volume distribution) were studied to assess the gas adsorption capacity. The results indicate that there is significant heterogeneity on coal surface, containing numerous channel-like pores, bottle-shaped pores and wedge-shaped pores. Both Langmuir volume (VL) and Langmuir pressure (PL) show a stage change trend with the increase of coalification degree. For different coalification stages, there exist different factors influencing the VL and PL values. For low-rank coals (Ro,max < 1.1%), the increase of VL values and decrease of PL values are mainly due to the abundant primary pore and fracture within coal. For middle-rank coals (1.1% < Ro,max < 2.1%), the moisture content, vitrinite content and total pore volume are all the factors influencing VL, and the reduction of PL is mainly attributed to the decrease of moisture content and inertinite content. Meanwhile, this result is also closely related to the pore shape. For high-rank coals (Ro,max > 2.1%), VL values gradually increase and reach the maximum. When the coal has evolved into anthracite, liquid hydrocarbon within pore begins pyrolysis and gradually disappears, and a large number of macropores are converted into micropores, leading to the increase of specific surface area and total pore volume, corresponding to the increase of VL. In addition, the increase of vitrinite content within coal also contributes to the increase of VL. PL, reaches the minimum, indicating that the adsorption rate reaches the largest at the low pressure stage. The result is mainly controlled by the specific surface area and total pore volume of coal samples. This research results will provide a clearer insight into the relationship between adsorption parameters and coal rank, moisture content, maceral composition and pore structure, and it is of great significance for better assessing the gas adsorption capacity.

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Pore Structure Characterization of TiO2-SiO2 Composite Aerogel Prepared via Ambient Pressure Drying by Sol Pre-Modification Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.534.101 ◽

2012 ◽

Vol 534 ◽

pp. 101-105 ◽

Cited By ~ 3

Author(s):

Jing Xiao Liu ◽

Lu Nan Bai ◽

Fei Shi ◽

Zhi Qiang Hu ◽

Yan Yan Jiang ◽

...

Keyword(s):

Specific Surface ◽

Pore Structure ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Ambient Pressure ◽

Volume Ratio ◽

Ambient Pressure Drying ◽

Composite Aerogel ◽

Composite Aerogels

In this paper, TiO2-SiO2composite aerogels were prepared via ambient pressure drying by sol-gel and sol pre-modification method. The pre-modification solution consists of hexamethyldisiloxane (HMDSO) as buffering agent, trimethylchlorosilane (TMCS) as modifier and hexane as organic solvent. The pore structure of TiO2-SiO2composite aerogels was characterized by N2adsorption-desorption method. The effects of HMDSO/TMCS volume ratio on the pore structure and properties of TiO2-SiO2composite aerogel were studied. The results indicate that the pre-modification of TiO2-SiO2composite sol by adding HMDSO/TMCS/Hexane solution could shorten the preparation period. Increasing the amount of HMDSO is favorable for obtaining TiO2-SiO2composite aerogel with higher specific surface area and pore volume. The best volume ratio of HMDSO/TMCS/composite sol for preparing mesoporous TiO2-SiO2composite aerogels were 12:6:120 and 12:12:120, with which the specific surface area and pore volume of the obtained TiO2-SiO2composite aerogel are 425.2～645.4 m2/g and 0.80～2.85 m3/g, respectively.

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Pore Structure Characteristics and Evolution Law of Different-Rank Coal Samples

Geofluids ◽

10.1155/2021/1505306 ◽

2021 ◽

Vol 2021 ◽

pp. 1-17

Author(s):

Zhihui Wen ◽

Qi Wang ◽

Yunpeng Yang ◽

Leilei Si

Keyword(s):

Specific Surface ◽

Pore Structure ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Volatile Matter ◽

Matter Content ◽

Full Size ◽

Structure Characteristics ◽

Volatile Matter Content

In this study, the full-size pore structure characteristics of six different-rank coal samples were investigated and analyzed from three perspectives, namely, pore shape, pore volume, and pore specific surface area, by performing a high-pressure mercury injection experiment and a low-temperature nitrogen adsorption experiment. Next, the full-size pore volumes and pore specific surface areas of the six coal samples were accurately characterized through a combination of the two experiments. Furthermore, the relationships between volatile matter content and pore volume and between volatile matter content and pore specific surface area were fitted and analyzed. Finally, the influences of metamorphic degree on pore structure were discussed. The following conclusions were obtained. The pore shapes of different-rank coal samples differ significantly. With the increase of metamorphic degree, the full-size pore volume and pore specific surface area both decrease first and then increase. Among the pores with various sizes, micropores are the largest contributor to the full-size pore volume and pore specific surface area. The fitting curves between volatile matter content and pore volume and between volatile matter content and pore specific surface area can well reflect the influence and control of metamorphic degree on pore volume and pore specific surface area, respectively. With the increase of volatile matter content, the pore volume and the pore specific surface area both vary in a trend resembling a reverse parabola.

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Pore Structure Regulation and Electrochemical Performance Characterization of Activated Carbon for Supercapacitors

Frontiers in Energy Research ◽

10.3389/fenrg.2021.680761 ◽

2021 ◽

Vol 9 ◽

Author(s):

Shijie Li ◽

Tao Xing ◽

Yilin Wang ◽

Pengwei Lu ◽

Weixue Kong ◽

...

Keyword(s):

Activated Carbon ◽

Specific Surface ◽

Pore Structure ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Activation Time ◽

Activation Temperature ◽

Specific Pore Volume ◽

Impregnation Time

In order to achieve the purpose of regulating the pore structure characteristics of activated carbon by adjusting the experimental parameters, the effects of carbonization temperature, carbonization time, pre-activation temperature, pre-activation time and impregnation time on the pore structure of sargassum-based activated carbon (SAC) are studied by orthogonal experiment. The gravimetric capacitance of SAC and the relationship between the gravimetric capacitance and specific surface area are also studied. The results show that the SACs prepared at all experimental conditions have developed pore structure and huge specific surface area, reaching 3,122 m2/g. The pore size of SAC is almost all within 6 nm, in which the micropores are mainly concentrated in 0.4–0.8 nm, the mesopores are mainly concentrated in 2–4 nm, and the number of micropores is significantly higher than that of mesopores. During the preparation of SAC, the effect of carbonization temperature on the specific surface area and specific pore volume of SAC is very significant. The effect of carbonization time on the specific surface area of SAC is significant, but the effect on specific pore volume can be ignored. The effects of pre-activation temperature, pre-activation time, and impregnation time on specific surface area and specific pore volume of SAC can be ignored. In addition, SACs show good gravimetric capacitance performance as electrode material for supercapacitors, which can significantly increase the capacitance of supercapacitors and thus broaden their applications. The gravimetric capacitance and specific surface area of SACs show a good linear relationship when the activated carbons have similar material properties and pore size distribution.

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Comparative Study on Shale Characteristics of Different Sedimentary Microfacies of Late Permian Longtan Formation in Southwestern Guizhou, China

Minerals ◽

10.3390/min9010020 ◽

2018 ◽

Vol 9 (1) ◽

pp. 20 ◽

Cited By ~ 4

Author(s):

Xiao Ma ◽

Shaobin Guo

Keyword(s):

Specific Surface ◽

Pore Structure ◽

Surface Area ◽

Mineral Composition ◽

Specific Surface Area ◽

Tidal Flat ◽

Pore Volume ◽

Clay Content ◽

Late Permian ◽

Sedimentary Microfacies

Organic-rich marine-continental transitional shales are widely distributed in Guizhou Province, China. Samples from the Late Permian Longtan Formation were investigated using organic petrography analysis, X-ray diffraction (XRD) analysis, field emission-scanning electron microscopy observations, mercury intrusion capillary pressure and gas adsorption experiments to better understand the organic geochemical characteristic, mineralogical composition, full-size pore structure characteristics and fractal characteristic of shale reservoir. The relationships among the total organic carbon (TOC) content, mineral composition, pore structure parameter, methane adsorption capacity and fractal dimension of shale samples are discussed, along with the differences between different sedimentary microfacies. Results show that shale samples are characterized by high TOC contents, low permeability, complex mineral composition and pore structure. Shales of YV-1, deposited in delta and lower delta plains, have an extreme high clay content (71.33% average) and the clay minerals mainly consist of the I/S and kaolinite, while shales of XD-1, deposited in the lagoon-tidal flat, have a relatively low clay content (37% average) and the I/S occupies an absolute advantage. The pore volume, specific surface area and average pore diameter of YV-1 (0.02881 cm3/g, 20.806 m2/g and 11.07 nm, respectively) are larger than that of XD-1 (0.02110 cm3/g, 20.101 m2/g, and 8.40 nm, respectively). The mesopore of YV-1 is the predominant contributor to the pore structure, while the micropore of XD-1 also occupies a certain proportion in addition to the mesopore. Organic matter (OM)-hosted pores are largely developed in XD-1 samples, while clay mineral-hosted pores dominate the pore system of YV-1. Shale samples with higher TOC content and clay content generally have larger specific surface area and pore volume, which provides more adsorption space and enhances pore structure heterogeneity. Samples of XD-1 have high TOC contents, suitable mineral composition and complex pore structure, suggesting that shales deposited in a lagoon-tidal flat environment may have a greater potential for shale gas development.

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Effects of Pore Structure of Different Rank Coals on Methane Adsorption Heat

Processes ◽

10.3390/pr9111971 ◽

2021 ◽

Vol 9 (11) ◽

pp. 1971

Author(s):

Haijian Li ◽

Shengcheng Wang ◽

Qiang Zeng ◽

Jianhong Kang ◽

Weiming Guan ◽

...

Keyword(s):

Carbon Dioxide ◽

Specific Surface ◽

Pore Structure ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Low Pressure ◽

Methane Adsorption ◽

Adsorption Heat ◽

Maximum Adsorption Capacity

Adsorption thermodynamic characteristics are an important part of the methane adsorption mechanism, and are useful for understanding the energy transmission mechanism of coalbed methane (CBM) migration in coal reservoirs. To study the effect of coal pore characteristics on methane adsorption heat, five different types of rank coals were used for low-pressure nitrogen, low-pressure carbon dioxide, and methane adsorption experiments. Pore structure and adsorption parameters, including maximum adsorption capacity and adsorption heat, were obtained for five coal samples, and their relationships were investigated. The results show that the low-pressure nitrogen adsorption method can measure pores within 1.7–300 nm, while the low-pressure carbon dioxide adsorption method can measure micropores within 0.38–1.14 nm. For the five coal samples, comprehensive pore structure parameters were obtained by combining the results of the low-pressure nitrogen and carbon dioxide adsorption experiments. The comprehensive results show that micropores contribute the most to the specific surface area of anthracite, lean coal, fat coal, and lignite, while mesopores contribute the most to the specific surface area of coking coal. Mesopores contribute the most to the pore volume of the five coal samples. The maximum adsorption capacity has a significant positive correlation with the specific surface area and pore volume of micropores less than 2 nm, indicating that methane is mainly adsorbed on the surface of micropores, and can also fill the micropores. The adsorption heat has a significant positive correlation with the specific surface area and pore volume of micropores within 0.38–0.76 nm, indicating that micropores in this range play a major role in determining the methane adsorption heat.

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