Abstract

Good quality Middle Miocene aged sandstones have been penetrated by numerous wells on the Malaka Shelf offshore North Sumatra. A sequence stratigraphic study using good quality 2D seismic, well data and biostratigraphic data indicates that most of these wells are in the Transgressive System Tract (TST), will act as continuous sheet sands, and will only be trapped structurally. By contrast, thick deep-water Low Stand System Tract (LST) basin floor fans are interpreted past the shelf to slope break and have the potential to form large stratigraphic traps.

The accumulations of basin floor fan sediments are interpreted and have an area of approximately 162.5 km². The mounded features show the high to low amplitude, discontinuous, convex upward character that may be interpreted to be localization of sand rich sediments. Successive lobes are deposited in the lows between the previous lobes. The prospective stratigraphic traps are ideally located next to the Lho Sukon Deep source kitchen that is known to have sourced most of the North Sumatra gas accumulations. The primary risk is interpreted to be updip seal of the stratigraphic traps and is dependent on the nondeposition of any sandstone thief zones in the bypass zone.