Sedimentology and stratigraphic architecture of a Miocene retrogradational, tide-dominated delta system: Balingian Province, offshore Sarawak, Malaysia
Meor H. Amir Hassan, Howard D. Johnson, Peter A. Allison, Wan H. Abdullah, 2017. "Sedimentology and stratigraphic architecture of a Miocene retrogradational, tide-dominated delta system: Balingian Province, offshore Sarawak, Malaysia", Sedimentology of Paralic Reservoirs: Recent Advances, G. J. Hampson, A. D. Reynolds, B. Kostic, M. R. Wells
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The Balingian Province of NW Borneo is a major hydrocarbon-bearing region with production dominantly from Early Miocene (cycle II) coastal to lower coastal plain deposits. A regional sedimentological synthesis is outlined from the main productive interval of three offshore oilfields, which are representative of the depositional environments and stratigraphic architecture in cycle II. Four types of vertical facies successions are recognized: (1) fluvio-tidal channel; (2) tide-dominated delta front; (3) wave-dominated shoreface; and (4) barrier lagoon. The facies successions demonstrate that cycle II consists of a tide-dominated delta system that is partly analogous to the modern Rajang Delta and Lupar Embayment of southern Sarawak. Fluvio-tidal channel and tide-dominated delta successions represent periods of river-fed progradation. Wave-dominated shoreface and barrier lagoon facies successions represent depositional systems that developed during periods of transgression and/or delta lobe abandonment. Cycle II consists of several high-order sequences stacked together into two lower-order, c. 100–300 m thick fining-upwards, unconformity-bounded megasequences. This stratigraphic architecture reflects a combination of hinterland denudation and long-term eustatic sea-level rise. These trends were interrupted by frequent, higher-order relative sea-level falls, which were a result of movement along the West Balingian Line fault zone. Variations in the thickness of megasequences between the three oilfields reflect fluctuations in tectonically driven subsidence rates. This exerted a fundamental control on the reservoir architecture, zonation and correlation and provides a basis for comparing field behaviour.
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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.