Guineco-Mebo campaign on board the “Pourquoi Pas”

The Guineco-Mebo campaign took place off the coast of Nigeria on board the oceanographic research vessel the “Pourquoi pas”, from October to November 2011. The campaign was initiated and run by the Ifremer “geological hazards” project in liaison with the University of Bremen (MARUM).

The two main objectives of this campaign were to determine the distribution of gas hydrates and to study the possible link between gas hydrate dynamics and the observed sedimentary deformations. During this campaign, several innovative tools were used, including the MeBo drilling tool developed by the University of Bremen and geotechnical monitoring tools developed by Ifremer (Penfeld and piezometers).

From a purely quantitative viewpoint, the campaign was a success as evidenced by the amount of data acquired: 372 m of drilling, 430 m of coring, 1413 m of Penfeld monitoring and 10 piezometric measurements. A variety of on-board techniques and measurements were conducted (geochemistry, infrared imaging, geotechnical techniques, acoustics) to determine the sediment’s physical and mechanical properties as well as to quantify gas hydrates and free gas contained in the sedimentary cores.

From a research perspective, a number of results already appear to be precursors. Examples include the detection of several faults saturated with free gas in the gas hydrate stability zone, but totally isolated from the surrounding medium and more specifically, seawater. A number of signs have emerged, showing that the gas hydrate formation process is much quicker than the dissolution process. Piezometric measurements have identified interstitial overpressures seemingly linked to the dissolution of gas hydrates and the formation of pockmarks.

The close-out meeting that took place on the Pourquoi pas was used as an opportunity to define topics of research that will be jointly conducted by Ifremer and the University of Bremen.