Seismic expression of gas and gas hydrates across the western Black Sea

Type Article
Date 2007-06
Language English
Author(s) Popescu Irina1, Lericolais GillesORCID2, Panin Nicolae3, De Batist Marc De1, Gillet Herve2
Affiliation(s) 1 : Univ Ghent, RCMG, B-9000 Ghent, Belgium.
2 : IFREMER, Ctr Brest, DRO, GM LES, F-29280 Plouzane, France.
3 : GeoEcoMar BucharesT, Bucharest 024053, Romania.
Source Geo-Marine Letters (0276-0460) (Springer), 2007-06 , Vol. 27 , N. 2-4 , P. 173-183
DOI 10.1007/s00367-007-0068-0
WOS© Times Cited 28
Abstract This study is a synthesis of gas-related features in recent sediments across the western Black Sea basin. The investigation is based on an extensive seismic dataset, and integrates published information from previous local studies. Our data reveal widespread occurrences of seismic facies indicating free gas in sediments and gas escape in the water column. The presence of gas hydrates is inferred from bottom-simulating reflections (BSRs). The distribution of the gas facies shows (1) major gas accumulations close to the seafloor in the coastal area and along the shelfbreak, (2) ubiquitous gas migration from the deeper subsurface on the shelf and (3) gas hydrate occurrences on the lower slope (below 750 m water depth). The coastal and shelfbreak shallow gas areas correspond to the highstand and lowstand depocentres, respectively. Gas in these areas most likely results from in situ degradation of biogenic methane, probably with a contribution of deep gas in the shelfbreak accumulation. On the western shelf, vertical gas migration appears to originate from a source of Eocene age or older and, in some cases, it is clearly related to known deep oil and gas fields. Gas release at the seafloor is abundant at water depths shallower than 725 m, which corresponds to the minimum theoretical depth for methane hydrate stability, but occurs only exceptionally at water depths where hydrates can form. As such, gas entering the hydrate stability field appears to form hydrates, acting as a buffer for gas migration towards the seafloor and subsequent escape.
Full Text
File Pages Size Access
publication-2615.pdf 29 1 MB Open access
Top of the page