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Title: Changes in pore structure of coal caused by coal-to-gas bioconversion

Microbial enhanced coalbed methane (ME-CBM) recovery is critically examined as a viable technology for natural gas recovery from coalbed methane (CBM) reservoirs. Since the majority of gas-in-place (GIP) is stored as an adsorbed phase in fine pores of coal matrix, the nano-pore structure directly influences gas storage and transport properties. Only limited studies have quantified the alteration of the nano-pore structure due to ME-CBM treatment. This study examines the evolution of the pore structure using a combination of small angle X-ray scattering (SAXS), low-pressure N 2 and CO 2 adsorption (LPGA) and high-pressure methane adsorption methods. The results show that the surface fractal dimension decreases for the two bioconverted coals compared to the untreated coal. After bio-treatment, the mesopore surface area and pore volume decrease with the average pore diameter increases, while the micropore surface area increases with pore volume decreases. Both inaccessible meso-/micropore size distributions decrease after bioconversion, while the accessible micropore size distribution increases, making a portion of closed micropore network accessible. In addition, the methane adsorption capacities increase after bio-treatment, which is confirmed by the increase of micropore surface area. A conceptual physical model of methanogenesis is proposed based on the evolution of the pore structure.
Authors:
 [1] ;  [1] ; ORCiD logo [2] ;  [1] ;  [1] ;  [1] ;  [3]
  1. Pennsylvania State Univ., University Park, PA (United States). Dept. of Energy and Mineral Engineering. G3 Center. Energy Inst.
  2. Bhabha Atomic Research Centre, Mumbai (India). Solid State Physics Division
  3. Southern Illinois Univ., Carbondale, IL (United States). Dept. of Civil and Environmental Engineering
Publication Date:
Grant/Contract Number:
FE0026161
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Pennsylvania State Univ., University Park, PA (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 01 COAL, LIGNITE, AND PEAT; environmental impact; environmental microbiology
OSTI Identifier:
1429067

Zhang, Rui, Liu, Shimin, Bahadur, Jitendra, Elsworth, Derek, Wang, Yi, Hu, Guanglong, and Liang, Yanna. Changes in pore structure of coal caused by coal-to-gas bioconversion. United States: N. p., Web. doi:10.1038/s41598-017-04110-z.
Zhang, Rui, Liu, Shimin, Bahadur, Jitendra, Elsworth, Derek, Wang, Yi, Hu, Guanglong, & Liang, Yanna. Changes in pore structure of coal caused by coal-to-gas bioconversion. United States. doi:10.1038/s41598-017-04110-z.
Zhang, Rui, Liu, Shimin, Bahadur, Jitendra, Elsworth, Derek, Wang, Yi, Hu, Guanglong, and Liang, Yanna. 2017. "Changes in pore structure of coal caused by coal-to-gas bioconversion". United States. doi:10.1038/s41598-017-04110-z. https://www.osti.gov/servlets/purl/1429067.
@article{osti_1429067,
title = {Changes in pore structure of coal caused by coal-to-gas bioconversion},
author = {Zhang, Rui and Liu, Shimin and Bahadur, Jitendra and Elsworth, Derek and Wang, Yi and Hu, Guanglong and Liang, Yanna},
abstractNote = {Microbial enhanced coalbed methane (ME-CBM) recovery is critically examined as a viable technology for natural gas recovery from coalbed methane (CBM) reservoirs. Since the majority of gas-in-place (GIP) is stored as an adsorbed phase in fine pores of coal matrix, the nano-pore structure directly influences gas storage and transport properties. Only limited studies have quantified the alteration of the nano-pore structure due to ME-CBM treatment. This study examines the evolution of the pore structure using a combination of small angle X-ray scattering (SAXS), low-pressure N2 and CO2 adsorption (LPGA) and high-pressure methane adsorption methods. The results show that the surface fractal dimension decreases for the two bioconverted coals compared to the untreated coal. After bio-treatment, the mesopore surface area and pore volume decrease with the average pore diameter increases, while the micropore surface area increases with pore volume decreases. Both inaccessible meso-/micropore size distributions decrease after bioconversion, while the accessible micropore size distribution increases, making a portion of closed micropore network accessible. In addition, the methane adsorption capacities increase after bio-treatment, which is confirmed by the increase of micropore surface area. A conceptual physical model of methanogenesis is proposed based on the evolution of the pore structure.},
doi = {10.1038/s41598-017-04110-z},
journal = {Scientific Reports},
number = ,
volume = 7,
place = {United States},
year = {2017},
month = {6}
}