Dynamics of fault-fluid-hydrate system around a shale-cored anticline in deepwater Nigeria

Type Article
Date 2011-12
Language English
Author(s) Sultan NabilORCID1, Riboulot VincentORCID1, Ker StephanORCID1, Marsset Bruno1, Geli LouisORCID1, Tary Jean-Baptiste1, Klingelhoefer FraukeORCID1, Voisset Michel1, Lanfumey Valentine1, Colliat Jean-Louis2, Adamy Jerome3, Grimaud S.2
Affiliation(s) 1 : IFREMER, Dept Geosci Marines, F-29280 Plouzane, France.
2 : Total, F-64018 Pau, France.
3 : Total, F-92078 Paris, La Defense, France.
Source Journal Of Geophysical Research-solid Earth (0148-0227) (Amer Geophysical Union), 2011-12 , Vol. 116 , N. B12110 , P. 22 p.
DOI 10.1029/2011JB008218
WOS© Times Cited 25
Abstract Gas hydrates were recovered by coring at the eastern border of a shale-cored anticline in the eastern Niger Delta. To characterize the link between faults and fluid release and to identify the role of fluid flow in the gas hydrate dynamics, three piezometers were deployed for periods ranging from 387 to 435 days. Two of them were deployed along a major fault linked to a shallow hydrocarbon reservoir while the third monitored the fluid pressure in a pockmark aligned above the same major fault. In addition, 10 ocean-bottom seismometers (OBS) were deployed for around 60 days. The piezometers simultaneously registered a prolonged fluid flow event lasting 90 days. During this time, OBS measurements record several episodic fluid release events. By combining and analyzing existing and newly acquired data, we show that the fluid-fault system operates according to the following three stages: (1) upward pore fluid migration through existing conduits and free gas circulation within several shallow sandy layers intersecting the major fault, (2) gas accumulation and pore pressure increases within sandy-silty layers, and (3) hydrofracturing and fluid pressure dissipation through sporadic degassing events, causing pore fluid circulation through shallow sandy layers and drawing overlying seawater into the sediment. This paper clearly demonstrates how an integrated approach based on seafloor observations, in situ measurements, and monitoring is essential for understanding fault-fluid-hydrate systems.
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Sultan Nabil, Riboulot Vincent, Ker Stephan, Marsset Bruno, Geli Louis, Tary Jean-Baptiste, Klingelhoefer Frauke, Voisset Michel, Lanfumey Valentine, Colliat Jean-Louis, Adamy Jerome, Grimaud S. (2011). Dynamics of fault-fluid-hydrate system around a shale-cored anticline in deepwater Nigeria. Journal Of Geophysical Research-solid Earth, 116(B12110), 22 p. Publisher's official version : https://doi.org/10.1029/2011JB008218 , Open Access version : https://archimer.ifremer.fr/doc/00060/17106/