Unexplored deepwater basins of North Andaman Sea

Deepwater basins of the North Andaman Sea in the northern edge of the Far East Archipelago were assessed recently by state-of-the-art seismic technology. The North Andaman Sea embraces several Tertiary basins consisting of a forearc basin, a volcanic arc, and a back-arc basin. Their massive but largely unknown stratigraphy consists of deeper Neogene lacustrine and deltaic sediments that infill basal synrift half-grabens, blanketed by massive sequences of the Late Oligocene, Miocene, and recent strata. In the extensional forearc, the deeper seismic marker horizons were structurally mapped and identified by acoustic impedance contrasts as carbonates, mass-transport complexes, synrift, and basement. The shallower Pliocene and Pleistocene sequences are dominated by low-seismic-velocity hemipelagic clays that were investigated using seismic attributes and seismic inversion. In the back arc, the relatively larger graben features were affected by tectonic inversion contemporaneous with the foundering of the basin into deep water in the Late Miocene. In the forearc and back arc, main hydrocarbon plays are the rimmed Early Miocene carbonate platforms, the paralic and deltaic sediments beneath the platform, and the deepwater clastics of hemipelagic clays and sands that form the dominant strata of the Mio-Pliocene. This modern seismic exploration involved acquisition, processing, and interpretation to assess the hydrocarbon prospectivity of undrilled deepwater regions in the forearc and back arc.