Relationship between fluid-escape pipes and hydrate distribution in offshore Sabah (NW Borneo)

This fluid flow system further impacts the gas hydrate distribution. The fluid-escape pipes can be locations where hydrates occur at high concentrations up to the seafloor if the pipe is presently active. Therefore, the observed up-bending of the stratigraphic reflections along the pipes are interpreted as a combination of a net volume increase of the host sediment owing to hydrate formation and seismic velocity pull-up effects. Away from the pipes, hydrates do not occur until 65-152 mbsf and are present only at low to moderate concentrations. At this site of focused fluid flow, fluid-escape pipes constitute, by volume, only 7-11% of the gas hydrate occurrence zone. Nevertheless, we predict that they could host between 20 and 50% of the whole hydrate volume. It is therefore likely that, in similar systems, a volumetrically significant portion of the total hydrate reservoir is hosted within fluid-escape pipes. The distribution of these features should thus be considered as a critical parameter for hydrate volume estimates.