Experimental study of supercritical methane adsorption in Longmaxi shale: Insights into the density of adsorbed methane

Zhou, Shangwen; Han, Xue; Yang, Ning; Guo, Wei; Zhang, Qin

doi:10.1016/j.fuel.2017.09.065

Cited by 205 publications

(233 citation statements)

References 42 publications

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“…The HPMA experiments on the coal and shale samples were tested at 60°C after blank and buoyancy experiments were performed. The excess adsorption capacity ( m ex ) measured at each equilibrium pressure point can be expressed as follows:

m_{ex} = Δ m - m_{sc} - m_{normals} + (V_{sc} + V_{normals}) \times ρ_{normalg}

where ∆ m is the balance reading, m sc is the mass of the sample container, m s is the mass of the sample, V sc is the volume of the sample container, V s is the volume of the sample, and ρ g is the bulk gas density. An evaluation of the real adsorption capacity of each sample requires the conversion of m ex to the absolute absorption capacity ( m abs ) via the determination of adsorbed‐phase density ( ρ a ) as:

m_{abs} = m_{ex} / false(1 - ρ_{g} false/ ρ_{a} false)

…”

Section: Samples and Experimentsmentioning

confidence: 99%

“…The methane adsorption capacity of coal is generally much larger than that of shale, with the difference in nanopore structure being one of the key factors for this difference in adsorption capacity. The SSA of porous media, such as coal, shale, and activated carbon, is the key parameter that influences the adsorption capacity of the adsorbents .…”

Section: Introductionmentioning

confidence: 99%

“…A larger SSA means the medium can provide more adsorption sites, resulting in a higher adsorption capacity . However, some studies have shown that a mismatching relationship between the methane adsorption capacities and SSAs of coal and shale exists, where coal has a smaller SSA but a stronger adsorption capacity. For example, Li et al indicated that the SSA of different‐rank coal samples is in the 0.059‐5.603 m 2 /g range, Shan et al demonstrated that vitrinite‐rich coals have an average SSA of 2.429 m 2 /g, and Tao et al found that the SSA of low‐rank coals is in the 0.19‐5.6 m 2 /g range, whereas many studies have shown that the SSA of the overmatured Longmaxi Formation shale can reach 10‐30 m 2 /g, which is obviously larger than that of coal.…”

Section: Introductionmentioning

confidence: 99%

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A comparative study of the nanopore structure characteristics of coals and Longmaxi shales in China

Zhou

Liu

Chen

et al. 2019

Energy Science & Engineering

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Both of the coalbed methane (CBM) and shale gas reservoirs are dominated by nanometer‐scale pores with their nanopore structures controlling the occurrence, enrichment, and accumulation of natural gas. Low‐pressure nitrogen gas adsorption (LP‐N2GA), low‐pressure carbon dioxide gas adsorption (LP‐CO2GA), high‐pressure methane adsorption (HPMA), and field emission scanning electron microscope (FE‐SEM) experiments were conducted on 14 different‐rank coal samples and nine Longmaxi shale samples collected from various basins in China to compare their nanopore characteristics. The FE‐SEM results indicate that the pore structures of both the coal and shale samples consist of nanometer‐sized pores that primarily developed in the organic matter. The types of their isothermal adsorption curves are similar. However, the coal and shale samples possess various hysteresis loops, which suggest that the nanopores in shale are open‐plated, whereas those in coal are semi‐open. Furthermore, the specific surface area (SSA) and pore volume (PV) of the micropores in coal are much larger than those of the mesopores, with the micropore SSAs accounting for 99% of the total SSA in the coal samples. However, the micropore SSAs in the shale samples only account 42.24% of the total SSA. These different nanopore structures reflect their different methane adsorption mechanisms. The methane adsorption of coal is primarily controlled by the micropore SSA, whereas that of shale is primarily controlled by the mesopore SSA. If we use mesopore SSA to analyze its impact on methane adsorption capacity of coal and shale, it will be mismatched. However, no mismatching relationship exists between the total SSAs and adsorption capacities of coal and shale. This study highlights the controlling effect of total SSA on methane adsorption capacity.

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m_{ex} = Δ m - m_{sc} - m_{normals} + (V_{sc} + V_{normals}) \times ρ_{normalg}

m_{abs} = m_{ex} / false(1 - ρ_{g} false/ ρ_{a} false)

…”

Section: Samples and Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A comparative study of the nanopore structure characteristics of coals and Longmaxi shales in China

Zhou

Liu

Chen

et al. 2019

Energy Science & Engineering

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“…Previous studies have shown that the degree of pore development of shale varies with maturity (Jop Klaver et al, 2015;Maxwell Pommer and Kitty Milliken, 2015). In view of the highly mature marine shale in southern China, some research clarifies the developmental characteristics of the shale pores of the Qiongzhusi Formation and the Wufeng-Longmaxi Formation (Shan et al, 2015;Ran et al, 2016Chen et al, 2017;Hou et al, 2017;Hu et al, 2017;Tong et al, 2017;Wang et al, 2017;Yang et al, 2017;Zhou et al;, and preliminarily clarified that tectonic movement and compressive stress have a destructive effect on nanopores in shale , Liang et al, 2017Cui et al, 2019;Zhu et al, 2018). This work screened the organic-rich shale samples from various locations and different strata (Wufeng Formation-Longmaxi Formation and Qiongzhusi Formation) in the middle and upper Yangtze regions, and systematically analyzed the pore characteristics of the shale to explain the differences in productivity.…”

Section: Introductionmentioning

confidence: 99%

Controlling Factors of Organic Nanopore Development: A Case Study on Marine Shale in the Middle and Upper Yangtze Region, South China

Liang

Zhang

Cui

et al. 2019

Acta Geologica Sinica (Eng)

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The Upper Ordovician Wufeng-Lower Silurian Longmaxi and the Lower Cambrian Qiongzhusi shales are the major targets for shale gas exploration and development in China. Although the two organic-rich shales share similar distribution ranges and thicknesses, they exhibit substantially different exploration and development results. This work analyzed the nanopore structures of the shale reservoirs in this region. Pore development of 51 shale samples collected from various formations and locations was compared using the petromineralogical, geochemical, structural geological and reservoir geological methods. The results indicate that the reservoir space in these shales is dominated by organic pores and the total pore volume of micropores, mesopores, macropores in different tectonic areas and formations show different trends with the increase of TOC. It is suggested that organic pores of shale can be well preserved in areas with simple structure and suitable preservation conditions, and the shale with smaller maximum ancient burial depth and later hydrocarbongeneration-end-time is also more conducive to pore preservation. Organic pore evolution models are established, and they are as follows: ① Organic matter pore development stage, ② Early stage of organic matter pore destruction, and ③ late stage of organic matter pore destruction. The areas conducive to pore development are favorable for shale gas development.Research results can effectively guide the optimization and evaluation of favorable areas of shale gas.

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“…In addition, methane in shale formations is typically in the supercritical state as the formation temperature and pressure far exceed its critical properties (-82.5 • C and 4.64 MPa) (Aranovich and Donohue, 270 Zhou, S., et al Advances in Geo-Energy Research 2018, 2(3): 269-281 1996; Do and Do, 2003). As for the adsorption of supercritical methane in shale, a common consensus has been established that the observed (excess) adsorption isotherms decrease in the high-pressure range (Do and Do, 2003;Gasparik et al, 2012;Tang et al, 2016;Tian et al, 2016;Zhou et al, 2018). Hence, the key issues remaining in this field is how to model these excess adsorption isotherms and reveal the real adsorption mechanism of shale gas under formation conditions.…”

Section: Introductionmentioning

confidence: 99%

Investigation of methane adsorption mechanism on Longmaxi shale by combining the micropore filling and monolayer coverage theories

Zhou

Yang

Wang

et al. 2018

Adv. Geo-Energy Res.

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Abstract:Understanding the methane adsorption mechanism is critical for studying shale gas storage and transport in shale nanopores. In this work, we conducted low-pressure nitrogen adsorption (LPNA), scanning electron microscopy (SEM), and high-pressure methane adsorption experiments on seven shale samples from the Longmaxi formation in Sichuan basin. LPNA and SEM results show that pores in the shale samples are mainly nanometersized and have a broad size distribution. We have also shown that methane should be not only adsorbed in micropores (< 2 nm) but also in mesopores (2-50 nm) by two hypotheses. Therefore, we established a novel DA-LF model by combining the micropore filling and monolayer coverage theories to describe the methane adsorption process in shale. This new model can fit the high-pressure isotherms quite well, and the fitting error of this new model is slightly smaller than the commonly used D-A and L-F models. The absolute adsorption isotherms and the capacities for micropores and mesopores can be calculated using this new model separately, showing that 77% to 97% of methane molecules are adsorbed in micropores. In addition, we conclude that the methane adsorption mechanism in shale is: the majority of methane molecules are filled in micropores, and the remainder are monolayer-adsorbed in mesopores. It is anticipated that our results provide a more accurate explanation of the shale gas adsorption mechanism in shale formations.

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Experimental study of supercritical methane adsorption in Longmaxi shale: Insights into the density of adsorbed methane

Cited by 205 publications

References 42 publications

A comparative study of the nanopore structure characteristics of coals and Longmaxi shales in China

A comparative study of the nanopore structure characteristics of coals and Longmaxi shales in China

Controlling Factors of Organic Nanopore Development: A Case Study on Marine Shale in the Middle and Upper Yangtze Region, South China

Investigation of methane adsorption mechanism on Longmaxi shale by combining the micropore filling and monolayer coverage theories

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