Carbon Dioxide (CO2) Adsorption Behaviour and Its Relationship with Nano-Structure in an Organic-Rich Shale: A Case Study of the Longmaxi Shale in Southeast Chongqing

2021 ◽  
Vol 21 (1) ◽  
pp. 362-370
Author(s):  
Meng Wang ◽  
Weidong Xie ◽  
Xuguang Dai ◽  
Kai Huang

Carbon capture and storage (CCS) technologies in shale reservoirs have attracted increasing interest in recent years. To study the CO2 adsorption behaviour in the Longmaxi shale, isothermal adsorption experiments, scanning electron microscopy (SEM) and other techniques were employed in this study. The results show that when the pressure is less than 7.37 MPa, the Langmuir model fits well with the experimental CO2 adsorption data in the shale. In contrast, when the pressure is greater than 7.37 MPa, the D+R-K model fits better with the experimental data. From low pressure to high pressure (>20 MPa), the CO2 adsorption isothermal curves can be divided into four stages: rapid adsorption stage, slow adsorption stage, linear decreasing stage and slightly decreasing stage. With increases in temperature, the CO2 adsorption capacity decreases as expected. In addition, the effects of the Longmaxi shale nano-structure on the CO2 adsorption behaviour were also investigated. It was found that organic matter has a greater influence than clay and quartz on the CO2 adsorption behaviour. Based on the SEM observations, large numbers of nanoscale organic pores were found in the shale samples, and these nanoscale organic pores may control the CO2 adsorption behaviour in organic-rich Longmaxi shale. With increasing total organic carbon (TOC) content, the CO2 adsorption capacity increases linearly. In this study, the characteristics of the CO2 adsorption in shale and its relationship with the shale nano-structure were studied, which may be helpful for understanding CCS technologies and their application in enhanced shale gas recovery.

2019 ◽  
Vol 7 (4) ◽  
pp. T843-T856
Author(s):  
Xinghua Wang ◽  
Arash Dahi Taleghani ◽  
Wenlong Ding

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.


Author(s):  
Shangbin Chen ◽  
Chu Zhang ◽  
Xueyuan Li ◽  
Yingkun Zhang ◽  
Xiaoqi Wang

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.


Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 957 ◽  
Author(s):  
Muhammad Usman ◽  
Ioannis Katsoyiannis ◽  
Manassis Mitrakas ◽  
Anastasios Zouboulis ◽  
Mathias Ernst

The small sized powdered ferric oxy-hydroxide, termed Dust Ferric Hydroxide (DFH), was applied in batch adsorption experiments to remove arsenic species from water. The DFH was characterized in terms of zero point charge, zeta potential, surface charge density, particle size and moisture content. Batch adsorption isotherm experiments indicated that the Freundlich model described the isothermal adsorption behavior of arsenic species notably well. The results indicated that the adsorption capacity of DFH in deionized ultrapure water, applying a residual equilibrium concentration of 10 µg/L at the equilibrium pH value of 7.9 ± 0.1, with a contact time of 96 h (i.e., Q10), was 6.9 and 3.5 µg/mg for As(V) and As(III), respectively, whereas the measured adsorption capacity of the conventionally used Granular Ferric Hydroxide (GFH), under similar conditions, was found to be 2.1 and 1.4 µg/mg for As(V) and As(III), respectively. Furthermore, the adsorption of arsenic species onto DFH in a Hamburg tap water matrix, as well as in an NSF challenge water matrix, was found to be significantly lower. The lowest recorded adsorption capacity at the same equilibrium concentration was 3.2 µg As(V)/mg and 1.1 µg As(III)/mg for the NSF water. Batch adsorption kinetics experiments were also conducted to study the impact of a water matrix on the behavior of removal kinetics for As(V) and As(III) species by DFH, and the respective data were best fitted to the second order kinetic model. The outcomes of this study confirm that the small sized iron oxide-based material, being a by-product of the production process of GFH adsorbent, has significant potential to be used for the adsorptive removal of arsenic species from water, especially when this material can be combined with the subsequent application of low-pressure membrane filtration/separation in a hybrid water treatment process.


2017 ◽  
Vol 2 (2) ◽  
pp. 90 ◽  
Author(s):  
Yulius Dala Ngapa

<p>Activation is one of the processes by which are mostly done to improve the quality of natural zeolite. Activation process by zeolite will change the ratio of the Si/Al and can increase the formation of empty cavities so that the capability of zeolite as an adsorbent be optimal. In this research, natural zeolite from the district of Ende, Nusa Tenggara Timur. Activation Ende natural zeolite done chemically using HCl and NaOH solution, with variations concentrate 0,5 M; 1,5 M; and 3,0 M. Next, zeolite which has activated used to adsorb dye methylene blue. Based on the research results, chemically of activation from natural zeolite can increase the adsorption capacity to substance methylene blue. The adsorption capacity in the Ende natural and after activation is 17,289 mg/g and 19,98 mg/g respectively. The Langmuir model most closely matched the isothermal adsorption of equilibrium process.</p>


2018 ◽  
Vol 16 (2) ◽  
pp. 138 ◽  
Author(s):  
Yulius Dala Ngapa ◽  
Sri Sugiarti ◽  
Zaenal Abidin

A synthetic zeolite was produced from natural zeolite from Ende-Nusa Tenggara Timur (NTT) by hydrothermal method. This study aims to produce synthetic zeolite from Ende natural zeolite to remove cation dye through the adsorption process. Temperature of crystal formation (ageing) was performed at 60 °C for 6 h and hydrothermal process was at 100 °C for 24 h. The natural zeolite produced synthetic NaP1 and synthetic Faujasite. Based on the research results, the synthesis of zeolite by the hydrothermal method can enhance the adsorption capacity and Cation Exchange Capacity (CEC). The adsorption capacity in the natural zeolites of type ZG, ZL and ZC before the hydrothermal process were 17.289, 17.276, and 16.483 mg/g, respectively, and after hydrothermal they increased to 37.398, 37.369 and 37.362 mg/g, respectively. In addition, the CEC increased from 84.154, 81.042, and 77.474 cmol/kg, respectively, to 244.063, 216.354, and 211.432 cmol/kg, respectively. The Langmuir model most closely matched the isothermal adsorption equilibrium process.


2017 ◽  
Vol 07 (12) ◽  
pp. 1819-1835 ◽  
Author(s):  
Taoyue Chang ◽  
Yuanli Shu ◽  
Yue Ma ◽  
Xinyi Xu ◽  
Yue Niu

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 986 ◽  
Author(s):  
Yingjin Wang ◽  
Dameng Liu ◽  
Yidong Cai ◽  
Xiawei Li

The petrophysical properties of coal will vary during coalification, and thus affect the methane adsorption capacity. In order to clarify the variation rule and its controlling effect on methane adsorption, various petrophysical tests including proximate analysis, moisture measurement, methane isothermal adsorption, mercury injection, etc. were carried out on 60 coal samples collected from the Junggar, Ordos and Qinshui basins in China. In this work, the boundary values of maximum vitrinite reflectance (Ro,m) for dividing low rank, medium rank and high rank coals are set as 0.65% and 2.0%. The results show that vitrinite is the most abundant maceral, but the maceral contents are controlled by sedimentation without any relation to coal rank. Both the moisture content and porosity results show higher values in the low ranks and stabilized with Ro,m beyond 1%. Ro,m and VL (daf) show quadratic correlation with the peak located in Ro,m = 4.5–5%, with the coefficient (R2) reaching 0.86. PL decrease rapidly before Ro,m = 1.5%, then increase slowly. DAP is established to quantify the inhibitory effect of moisture on methane adsorption capacity, which shows periodic relationship with Ro,m: the inhibitory effect in lignite is the weakest and increases during coalification, then remains constant at Ro,m = 1.8% to 3.5%, and finally increases again. In the high metamorphic stage, clay minerals are more moisture-absorbent than coal, and the inherent moisture negatively correlates with the ratio of vitrinite to inertinite (V/I). During coalification, micro gas pores gradually become dominant, fractures tends to be well oriented and extended, and clay filling becomes more common. These findings can help us better understand the variation of petrophysical properties and adsorption capacity in different rank coals.


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