Gas hydrate distributions in sediments of pockmarks from the Nigerian margin - results and interpretation from shallow drilling

Jiangong Wei*, Thomas Pape, Nabil Sultan, Jean-Louis Colliat, Tobias Himmler, Livio Ruffine, Alexis de Prunelé, Bernard Dennielou, Sebastien Garziglia, Tania Marsset, Carl A. Peters, Abdulkarim Rabiu, Gerhard Bohrmann

*Corresponding author for this work

    Research output: Contribution to journalArticle

    32 Citations (Scopus)

    Abstract

    A joint research expedition between the French IFREMER and the German MARUM was conducted in 2011 using the R/V 'Pourquoi pas?' to study gas hydrate distributions in a pockmark field (1141-1199m below sea surface) at the continental margin of Nigeria. The seafloor drill rig MeBo of MARUM was used to recover sediments as deep as 56.74m below seafloor. The presence of gas hydrates in specific core sections was deduced from temperature anomalies recorded during continuous records of infrared thermal scanning and anomalies in pore water chloride concentrations. In situ sediment temperature measurements showed elevated geothermal gradients of up to 258°C/km in the center of the so-called pockmark A which is up to 4.6 times higher than that in the background sediment (72°C/km). The gas hydrate distribution and thermal regime in the pockmark are largely controlled by the intensity, periodicity and direction of fluid flow. The joint interaction between fluid flow, gas hydrate formation and dissolution, and the thermal regime governs pockmark formation and evolution on the Nigerian continental margin.

    Original languageEnglish
    Pages (from-to)359-370
    Number of pages12
    JournalMarine and Petroleum Geology
    Volume59
    DOIs
    Publication statusPublished - Jan 2015

    Keywords

    • Chloride profile
    • Fluid flow
    • Gas hydrate
    • Infrared thermal imaging
    • MeBo drill rig
    • Nigerian continental margin
    • Pockmark

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