Biogenic methane and carbon dioxide generation in organic-rich shales from southeastern Brazil

Biogenic methane and carbon dioxide generation in organic-rich shales from southeastern Brazil

Brazilian shale formations are potential biogenic gas systems that are still poorly understood. Organic-rich shales from Ponta Grossa (Devonian, Paraná Basin), Irati (Permian, Paraná Basin) and Tremembé (Paleogene, Taubaté Basin) Formations were analyzed in order to evaluate their biogenic methane (...

Full description

Saved in:
Bibliographic Details
Published in:International journal of coal geology Vol. 162; pp. 1 - 13
Main Authors: Bertassoli, D.J., Sawakuchi, H.O., Almeida, N.S., Castanheira, B., Alem, V.A.T., Camargo, M.G.P., Krusche, A.V., Brochsztain, S., Sawakuchi, A.O.
Format: Journal Article
Language:English
Published: Elsevier B.V 15-05-2016
Subjects:
Basins
Biogenic gas
Carbon dioxide
Climate change
Drying
Formations
Geologic emissions of greenhouse gases
Geology
Methane
Nitrogen adsorption
Paraná Basin
Pore structure
Shale
Shale gas
Specific surface
Taubaté Basin
Geologic emissions of greenhouse gases
Climate change
Biogenic gas
Pore structure
Paraná Basin
Nitrogen adsorption
Taubaté Basin
Shale gas
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Brazilian shale formations are potential biogenic gas systems that are still poorly understood. Organic-rich shales from Ponta Grossa (Devonian, Paraná Basin), Irati (Permian, Paraná Basin) and Tremembé (Paleogene, Taubaté Basin) Formations were analyzed in order to evaluate their biogenic methane (CH4) generation potential and to constrain environmental and geological conditions that may affect methanogenic metabolism. Additionally, the generation potential of carbon dioxide (CO2) was evaluated in combination with CH4 to constrain Brazilian organic-rich shales as sources of greenhouse gas to the atmosphere. Twenty-four shale samples were used for batch incubations in dry and wet conditions and after headspace refilling and acetic acid addition during one year. Physico-chemical parameters such as Total Organic Carbon (TOC), specific surface area and pore volume were characterized in order to understand general geologic controls on CH4 and CO2 production. Biogenic gas generation rates in dry tests reached up to 3.17ml/t·d (milliliter per ton of shale per day) for CH4 and 2.45×103ml/t·d for CO2 during the first 30days, with wet samples producing about 54% more CH4 and 151% more CO2 than dry samples. Headspace refilling did not demonstrate significant changes on production rates, while acetic acid addition restarted or increased CH4 and CO2 production rates in several microcosms. Shales from the Irati Formation showed the highest methane production rates for both dry and wet tests, with unusual ranges of δ13CCH4 and δ13CCO2 that may be linked to hydrocarbon biodegradation. The studied shale formations have different pore volume and specific surface area, but without significant influence over biogenic methane generation. •Pore structure and biogenic gas generation varied among Brazilian shales.•Batch incubations presented significant accumulation of biogenic CH4 and CO2.•Water and organic content controlled gas production in incubation experiments.•Pore volume and specific surface area did not control methanogenic production.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:0166-5162
1872-7840
DOI:10.1016/j.coal.2016.05.013