Publication Date:
2021-01-18
Description:
We studied a large dataset of 2600 shale gas samples from 76 geological formations in 38 sedimentary
basins located in eleven countries. Shale gases contain mostly hydrocarbons dominated by methane.
Shale gases can have primary microbial, secondary microbial and thermogenic origin. However, gases
produced from most commercially successful shale plays (e.g., the Marcellus, Haynesville, Eagle Ford
and Barnett in the USA, the Vaca Muerta in Argentina and the Wufeng-Longmaxi in China) are thermogenic.
It appears that formations with greater gas endowment such as the Marcellus and the Haynesville
contain late-mature thermogenic gas. Shale plays with early-mature thermogenic and secondary microbial
gas such as the Antrim (USA) and the New Albany (USA) formations have relatively low endowments
of recoverable gas. Shale plays with primary microbial gas are not significant from commercial exploration
perspective. Isotope reversals (d13C of methane 〉 d13C of ethane) are observed in shale plays with
mature organic matter (vitrinite reflectance 〉 2%) that experienced significant uplift (〉2 km). It appears
that isotope fractionation during desorption from depressurized late-mature shales leads to isotope
reversal in the residual gas produced from shale formations (e.g., the Wufeng-Longmaxi). Significant
contribution of adsorbed gas (enriched in 13C-rich C2+ hydrocarbons relative to the co-occurring free
gas) in the production from some plays (e.g., the Fayetteville, USA) may result in isotope rollovers.
Description:
Published
Description:
103997
Description:
6A. Geochimica per l'ambiente e geologia medica
Description:
JCR Journal
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
