Transgressive successions of the Mahakam Delta Province, Indonesia
Joseph J. Lambiase, Ridha S. Riadi, Nadia Nirsal, Salahuddin Husein, 2017. "Transgressive successions of the Mahakam Delta Province, Indonesia", Sedimentology of Paralic Reservoirs: Recent Advances, G. J. Hampson, A. D. Reynolds, B. Kostic, M. R. Wells
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Sedimentological and stratigraphic analysis of outcrops and subsurface data in the Mahakam Delta province, combined with concepts of transgressive sedimentary processes derived from a study of the modern Mahakam Delta, indicate that a significant portion of the palaeo-Mahakam Delta succession was deposited during transgressive phases. Some of the transgressive successions resulted from major transgressions and are regionally extensive, but many reflect small, short-lived transgressions within dominantly progradational phases.
Two sandstone facies with significant reservoir potential are common within the transgressive successions. Backfilled distributary sandstones occur in outcrop as 10–20 m thick, fining-upward channel sands that become more marine upward and in the subsurface as elongate, coastline-perpendicular sand bodies with a back-stepping stratigraphic architecture and highly variable thickness. Transgressive shoreline sandstones also fine upward, but they are shoreline-parallel, their lateral extent is controlled by the pre-transgression delta morphology and their thickness depends on the rate of relative sea-level rise.
Both types of transgressive sandstone can be difficult to distinguish from specific progradational sandstones with wireline log data, especially when they occur within predominantly progradational successions. However, their sand body geometries, volumetrics and connectivity are much different from the stratigraphically adjacent sandstones deposited during progradational phases of deltaic deposition.
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Paralic reservoirs reflect a range of depositional environments including deltas, shoreline-shelf systems and estuaries. They provide the backbone of production in many mature basins, and contribute significantly to global conventional hydrocarbon production. However, the range of environments, together with relative sea-level and sediment supply changes, result in significant variability in their stratigraphic architecture and sedimentological heterogeneity, which translates into complex patterns of reservoir distribution and production that are challenging to predict, optimize and manage.
This volume presents new research and developments in established approaches to the exploration and production of paralic reservoirs. The 13 papers in the volume are grouped into three thematic sections, which address: the sedimentological characterization of paralic reservoirs using subsurface data; lithological heterogeneity in paralic depositional systems arising from the influence of tidal currents; and paralic reservoir analogue studies of modern sediments and ancient outcrops. The volume demonstrates that heterogeneity in paralic reservoirs is increasingly well understood at all scales, but highlights gaps in our knowledge and areas of current research.