A new method for the quantification of hydrogen contribution from water to methane during hydrous kerogen pyrolysis. (November 2022)

• Record Type: Journal Article
• Authors: Li, Shida; Wei, Zhiwei; Liu, Hu; Cheng, Bin; Xu, Jianbin; Liao, Zewen
• Is Part Of: Organic geochemistry. Volume 173(2022)
• Publication Date: 2022-11
• Subjects: Water contribution -- Shale gas -- Stable hydrogen isotope -- Quantification assessment -- Kerogen hydrous pyrolysis; Organic geochemistry -- Periodicals; Biogeochemistry -- Periodicals; Géochimie organique -- Périodiques; 553.205
• DOI: 10.1016/j.orggeochem.2022.104495
• Languages: English
• ISSNs: 0146-6380

Abstract

Highlights: Water contributes hydrogen to form methane at hydrous kerogen pyrolysis. Tracing 2 H amount transferred from H2 O to CH4 to calculate water contribution. Labeling experiments indicate 12.91–15.15% of methane hydrogen is derived from water. The proportion of water-derived hydrogen in methane increases with higher thermal maturity. Abstract: Hydrogen from stratigraphic water may compensate for H-depleted kerogen, and it may produce more shale gas resources. The contribution of water-derived hydrogen to methane was calculated via deuterium atom transfer from labelled water (enriched 2 H) to the methane generated from the pyrolysis experiments of high-maturity kerogen. The results showed that methane had enriched 2 H up to 8040–9509 ‰ with labelled water addition. According to deuterium atom transfer calculations, we found that water contributes 12.91–15.15 % hydrogen to methane, with the contribution proportion increasing with increasing thermal maturity. These results suggest that in high-over matured shale rocks, water might contribute to shale gas reserves for late methane generation from the residual hydrogen-exhausted kerogen.