Title: Geomechanical and flow implications with continued bioconversion of coal to methane: Experiments and modeling

Abstract

Microbial conversion of coal to methane is a promising technology during transition of coal-based energy from conventional coal mining to natural gas recovery from coal. Significant research advances have been made towards engineering ideal microbial communities and nutrients for bio-stimulation of coal. However, actual field applications require geomechanical and flow behavior characterization of coal during the bioconversion process as well as gas production over the life of the created “biogenic gas reservoirs”. This work presents the results of an experimental investigation to estimate gas/methane production using bioconversion of coal and analyses of variations in bulk modulus, strain and permeability. Bulk modulus of coal demonstrated time-dependent behavior with continued bioconversion of solid coal. The phenomenon was modeled using mass balancing in a closed environment and the logistic equation based biogenic gas production with time. The modeled gas production and changes in modulus of coal showed excellent agreement with the corresponding experimental results. Next, numerical simulation of biogenic conversion of coal in a constant stress in-situ condition, replicating the Huff ‘n Puff method under field conditions, was carried out. The results showed that bioconversion can lead to decrease in effective stress, increase in permeability and decrease in the modulus of coal withmore » time. Repeated recharge of coal with nutrients and recovering the produced gas, that is, sequential cycles of Huff n’ Puff, showed further increase in permeability and decrease in coal strength, potentially leading to coal failure in-situ, further increasing the permeability, thus enhancing the prospect of field application of the technology.« less

Authors:

Saurabh, Suman ^[1]; Harpalani, Satya ^[1]

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+ Show Author Affiliations

1. Southern Illinois Univ., Carbondale, IL (United States)

Publication Date:

Sat Feb 13 00:00:00 EST 2021

Research Org.:

Pennsylvania State Univ., University Park, PA (United States)

Sponsoring Org.:

USDOE Office of Fossil Energy (FE); USDOE

OSTI Identifier:

1849165

Alternate Identifier(s):

OSTI ID: 1775778

Grant/Contract Number:  

FE0026161

Resource Type:

Accepted Manuscript

Journal Name:

Fuel

Additional Journal Information:

Journal Volume: 292; Journal Issue: C; Journal ID: ISSN 0016-2361

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

01 COAL, LIGNITE, AND PEAT; Energy & fuels; Engineering; Coal bioconversion; Geomechanics; Flow characterization; Field application