Balingian Province is a prolific hydrocarbon-producing region in Sarawak Basin which has received great interest in the past years leading to good understanding of the regional tectonic and sedi-mentation history. However, few studies had focus on field-scale level to address reservoir complexity associated with marginal marine setting. This study attempts to highlight on the sedimentology and stratigraphy of Cycle II (Early Miocene) reservoir interval in a mature brownfield of Temana using primarily core and well log data. The facies analysis of core reveals interbedded units of sandstone and mudstone with diverse tidal and wave sedimentary structures as well as abundant trace fossils of mixed skolithos and cruziana ichnofacies representing brackish water to open marine assemblages. Depositional model of the reservoir interval is proposed as succession of delta and estuary subjected to mixed tidal and wave energy, followed by open marine shelf resulting from marine transgression of the coastal area. Well stratal pattern of the reservoir interval depicts stratigraphic architecture that is composed of high-frequency transgressive-regressive (T-R) cycles nestled within larger retro-gradationally stacked 3rd-order sequences. This study demonstrated that sedimentological and strati-graphic analysis using core and well log can provide valuable input on the reservoir lateral and vertical heterogeneity thus improving well-to-well correlation and facies prediction to support field deve-lopment strategy. © 2023, Petroleum and Coal. All Rights Reserved.