摘要
High resolution seismic data and newly acquired logging data reveal the presence of gas hydrates in the deep-water area in the northeastern Bay of Bengal.Bottom Simulating Reflectors(BSRs)appear at 430 ms beneath the seafloor,with the features of typical gas hydrates reported elsewhere except for some discontinuity.The BSR distribution is closely related to the position of anticline structures and turbidite channels.Anticlines provide conduits for the upward migration of gases from deeper intervals,while the turbidite sands within channels act as reservoirs for gas hydrate accumulation.High sedimentation rates in the Bengal Fan were ge-nerally favorable to produce a great amount of methane gas,providing favorable preconditions for the formation of gas hydrates.The discovery of gases in adjacent area indicates the contribution of the biogenic gas to the formation of gas hydrates.Meanwhile,seismic sections provide the evidence for the potential thermogenic gas kitchen in deep intervals.The anticline structures and the associated vertical fractures may constitute vertical fluid flowing conduits,which hydraulically connect the two deeper thermogenic petroleum systems(i.e.,rifting and Eocene-Oligocene source rocks)with the turbidite reservoirs and thus facilitate the fluid migration from the sources to the reservoirs,generating favorable conditions for gas-hydrate accumulation in such foreland setting.
基金
We wish to thank the China National Oil and Gas Exploration and Development Company(CNODC)and Hangzhou Research Institute of Geology research team for providing the seismic data and approving this publication.The research is funded by the National Natural Science Foundation of China(Nos.92055211,42076219,42006067)
the Construction Project of China ASEAN Marine Seismic Data Platform and Research Center(No.1212010050017001).
