Types of fluid-related features controlled by sedimentary cycles and fault network in deepwater Nigeria

Type Article
Date 2018-01
Language English
Author(s) Marsset TaniaORCID1, Ruffine LivioORCID1, Ker StephanORCID1, Cauquil E.3, Gay Aurelien2
Affiliation(s) 1 : Ifremer Inst Francais Rech Exploitat Mer, UR GM, BP 70, F-29280 Plouzane, France.
2 : Univ Montpellier 2, Geosci Montpellier, UMR CC 5243 60, Pl E Bataillon, F-34095 Montpellier 5, France.
3 : TOTAL, Explorat & Prod, 24 Cours Michelet, F-92069 Paris, France.
Source Marine And Petroleum Geology (0264-8172) (Elsevier Sci Ltd), 2018-01 , Vol. 89 , N. Part.2 , P. 330-349
DOI 10.1016/j.marpetgeo.2017.10.004
WOS© Times Cited 4
Keyword(s) Niger delta, Fluid flow, Pockmark, Gas hydrates, Methane-derived carbonate, Fault network, Sedimentary cycles
Abstract

The seismic characteristics of focused fluid-related features such as pockmarks and carbonate build-ups on the Nigerian continental slope have been investigated using complementary seismic data sets (reprocessed 3D exploration data and 2D Very High Resolution hull-mounted and near-bottom seismic data) coupled with the results of previous studies (sedimentological, geotechnical and geochemical analyses).

The results show different types of fluid-related features within the hemipelagic phase of long duration (∼1 Myr) Turbidite/Hemipelagic cycles. They are the product of the disturbance of the hosting sediments following two main distinct processes: (1) no or low sediment deposition caused by fluid escape associated with seafloor settlement (benthic fauna, carbonate precipitation, gas hydrate formation) and (2) post-depositional erosion, caused either by fluid release (dewatering from underlying features such as channels and upward migration from a deep source) or by collapse (destabilisation of gas hydrates). The temporal evolution reveals a decrease in fluid flow during the hemipelagic deposition as witnessed by the decrease in methanogenic activity and by gas hydrate destabilisation. The spatial distribution of fluid-related features seems to be controlled by the type of fault (small fault or structural lineament).

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