Publications

Sihapas Formation is known as a good resevoir in Central Sumatran Basin. It is Early Miocene in age and occurs as arenite sandstone with wide distibution througout western Central Sumatra Basin. Observations of lithology, sedimentary structures, and trace fossils in the Well X core interval indicate four facies associations. Those facies are sand bars, sand flat, transgressive lag, and mud flat. Sand bars comprise moderate to fine sandstone, planar bidirectional crossbedding, and locally found trace fossil, upward we found sand flat and transgressive lag as a mark of trangression. Rise and fall of relative sea level changes are recorded in several intervals upward of trangressive lag facies until mud flat facies in uppermost section. Bioturbation, compaction, cementation, and replacement are recorded in twenty thin sections sampled from conventional core indicating that the sediments have been through eogenesis and mesogenesis phase. The objective of this paper is to provide detailed sedimentological descriptions, petrography and diagenesis of estuarine deposits of Sihapas Formation to assist and encourage future exploration and development. Keywords: sedimentology, diagenesis, estuary, Sihapas, central sumatran basin