Cyclic Fluctuations in Gradient Change Within the Bengal Fan: A High Resolution Seismic Stratigraphic Analysis of Channel Architecture and Geomorphology, Offshore Myanmar
The of channel systems at the complex and complex set scale in the shallow Bengal Fan indicate an intricate depositional history with multiple forcing agents controlling channel geomorphology and architecture. Cyclic fluctuations in gradient change are apparent in the repetitive nature of stacking patterns that range from weakly confined to disorganized channel complex sets. This intricate architecture has implications for the greater hydrocarbon system assessment impacting reservoir continuity, lateral and top seal integrity, and hydrocarbon migration. The size, complex channel geomorphology, and mud-rich nature of the Bengal Fan system makes analogue selection for hydrocarbon prospective sections challenging. In the case of the Bengal Fan, the most appropriate analogue may be the Bengal Fan itself. Analysis of channel architecture and geomorphology in the shallow Bengal Fan provides clues to the intricacy of the channel architecture through the evolutionary history of the fan. Channel orientation varies from due north-south to west-east, the former functioning as the primary transport direction and the latter more commonly associated with potential splay deposition. Sinuosity ranges from highly sinuous to straight, and channels often display complex cross-cutting relationships. Width of individual channel complexes ranges from 1 km to over 8 km, depending on channel sinuosity. Larger scale channel complexes appear to amalgamate, at times displaying a weakly confined channel system geomorphologic pattern. Channel complex sets stack to form channel fairways often resembling a slope valley-like architecture and can reach over 16 km in width. Channel fill is interpreted as primarily mud-prone, with occasional sand-prone fill. Patterns suggesting overbank splay deposits are also observed occasionally. A depositional stacking pattern is observed with predominantly weakly confined channel systems at the base. As the system evolves, these weakly confined channels begin to isolate into disorganized channel systems with more discernable lateral boundaries. These disorganized channel systems further evolve vertically to a more organized channel complex geomorphology. Recent high resolution seismic data and state of the art seismic stratigraphic workflows allow for detailed geomorphologic analysis of the shallow Bengal Fan. The compound channel architecture and stacking patterns observed detail a complicated and interesting geologic history.
AAPG Datapages/Search and Discovery Article #90336 ©2018 AAPG Asia Pacific Region, The 4th AAPG/EAGE/MGS Myanmar Oil and Gas Conference, Myanmar: A Global Oil and Gas Hotspot: Unleashing the Petroleum Systems Potential, Yangon, Myanmar, November 13-15, 2018