Anthropogenic and natural methane emissions from a shale gas exploration area of Quebec, Canada.
The increasing number of studies on the determination of natural methane in groundwater of shale gas prospection areas offers a unique opportunity for refining the quantification of natural methane emissions. Here methane emissions, computed from four potential sources, are reported for an area of ca. 16,500km(2) of the St. Lawrence Lowlands, Quebec (Canada), where Utica shales are targeted by the petroleum industry. Methane emissions can be caused by 1) groundwater degassing as a result of groundwater abstraction for domestic and municipal uses; 2) groundwater discharge along rivers; 3) migration to the surface by (macro- and micro-) diffuse seepage; 4) degassing of hydraulic fracturing fluids during first phases of drilling. Methane emissions related to groundwater discharge to rivers (2.47×10(-4) to 9.35×10(-3)Tgyr(-1)) surpass those of diffuse seepage (4.13×10(-6) to 7.14×10(-5)Tgyr(-1)) and groundwater abstraction (6.35×10(-6) to 2.49×10(-4)Tgyr(-1)). The methane emission from the degassing of flowback waters during drilling of the Utica shale over a 10- to 20-year horizon is estimated from 2.55×10(-3) to 1.62×10(-2)Tgyr(-1). These emissions are from one third to sixty-six times the methane emissions from groundwater discharge to rivers. This study shows that different methane emission sources need to be considered in environmental assessments of methane exploitation projects to better understand their impacts.
GEOTOP and Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, CP 8888, Succ. Centre-Ville, Montréal, QC H3C 1P8, Canada. Electronic address: pinti.daniele@uqam.ca.
Daniele L
DL
Pinti
GEOTOP and Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St. West, Montreal, QC H4B 1R6, Canada.
Yves
Y
Gelinas
GEOTOP and Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St. West, Montreal, QC H4B 1R6, Canada.
Anja M
AM
Moritz
GEOTOP and Département des sciences de la Terre et de l'atmosphère, Université du Québec à Montréal, CP 8888, Succ. Centre-Ville, Montréal, QC H3C 1P8, Canada.
Marie
M
Larocque
Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba 277-8564, Japan; Department of Geosciences, National Taiwan University, Roosevelt Road, Taipei 106, Taiwan.
Yuji
Y
Sano
D004784:Environmental Monitoring; D060587:Groundwater / Q000032:analysis*; D008697:Methane / Q000032:analysis*; D061329:Oil and Gas Fields; D011792:Quebec; D014874:Water Pollutants, Chemical / Q000032:analysis*
D014874:Water Pollutants, Chemical; D008697:Methane
Emissions; Groundwater; Methane (CH(4)); Quebec (Canada); Shale gas