Facies distribution and sedimentary processes on the modern Baram Delta: implications for the reservoir sandstones of NW Borneo

Abstract

The Baram Delta has been classified as wave-dominated and as a modern analogue for the prolific Tertiary sandstone reservoirs in the Baram Delta Province of NW Borneo. However, the delta's facies distribution and sedimentary processes indicate that sedimentation is presently occurring only on the large mouth bar and that the Baram is more properly categorised as a mixed wave and tide-influenced delta. More than half of the surface area of the mouth bar is dominated by tidal currents and covered with tidally deposited sediments because a relatively large tidal prism controls the nearshore hydrodynamics. Conversely, the widespread Tertiary shoreface reservoir sandstones are clearly wave-dominant and tidal signatures are absent. Consequently, the Baram Delta is not an appropriate analogue for most shoreface reservoir sandstones in NW Borneo.