Open Access3‐D basin‐scale reconstruction of natural gas hydrate system of the G reen C anyon, G ulf of M exico
Author(s) -
Burwicz Ewa,
Reichel Thomas,
Wallmann Klaus,
Rottke Wolf,
Haeckel Matthias,
Hensen Christian
Publication year - 2017
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2017gc006876
Subject(s) - geology , clathrate hydrate , natural gas , sedimentary depositional environment , geochemistry , geomorphology , structural basin , petrology , hydrate , chemistry , organic chemistry
Our study presents a basin‐scale 3‐D modeling solution, quantifying and exploring gas hydrate accumulations in the marine environment around the Green Canyon (GC955) area, Gulf of Mexico. It is the first modeling study that considers the full complexity of gas hydrate formation in a natural geological system. Overall, it comprises a comprehensive basin reconstruction, accounting for depositional and transient thermal history of the basin, source rock maturation, petroleum components generation, expulsion and migration, salt tectonics, and associated multistage fault development. The resulting 3‐D gas hydrate distribution in the Green Canyon area is consistent with independent borehole observations. An important mechanism identified in this study and leading to high gas hydrate saturation (>80 vol %) at the base of the gas hydrate stability zone (GHSZ) is the recycling of gas hydrate and free gas enhanced by high Neogene sedimentation rates in the region. Our model predicts the rapid development of secondary intrasalt minibasins situated on top of the allochthonous salt deposits which leads to significant sediment subsidence and an ensuing dislocation of the lower GHSZ boundary. Consequently, large amounts of gas hydrates located in the deepest parts of the basin dissociate and the released free methane gas migrates upward to recharge the GHSZ. In total, we have predicted the gas hydrate budget for the Green Canyon area that amounts to ∼3256 Mt of gas hydrate, which is equivalent to ∼340 Mt of carbon (∼7 × 10 11 m 3 of CH 4 at STP conditions), and consists mostly of biogenic hydrates.