Evidence for massive emission of methane from a deep-water gas field during the Pliocene.

ABSTRACT: Geologic hydrocarbon seepage is considered to be the dominant natural source of atmospheric methane in terrestrial and shallow-water areas; in deep-water areas, in contrast, hydrocarbon seepage is expected to have no atmospheric impact because the gas is typically consumed throughout the water column. Here, we present evidence for a sudden expulsion of a reservoir-size quantity of methane from a deep-water seep during the Pliocene, resulting from natural reservoir overpressure. Combining three-dimensional seismic data, borehole data and fluid-flow modeling, we estimate that 18-27 of the 23-31 Tg of methane released at the seafloor could have reached the atmosphere over 39-241 days. This emission is ∼10% and ∼28% of present-day, annual natural and petroleum-industry methane emissions, respe

SUBMITTER: Foschi M 

PROVIDER: S-EPMC7668107 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature