This paper presents lithofacies types of exposed Nyalau Formation in areas around Bintulu town, Sarawak, Malaysia. The Early Miocene exposures of Nyalau Formation provide a unique opportunity to study the sedimentology and sequences at reservoir scale in order to understand the depositional and post depositional changes. Here, we describe the results of description of nine sections in general in the form of fifteen LFTs (Lithofacies Types) combined into nine FA (Facies Association). Later, Sungai Mas Camp section one of these nine sections describes in order to understand the lateral and vertical distribution of these facies associations. Overall, the facies associations varies from mangrove, tidal flat, tidal bar, subtidal flat, lower shoreface, upper shoreface, tidal influenced channels, tidal dominated channels, offshore settings depending on the location of studied sections. However, Sungai Mas Camp section presents fluctuations in mangrove FA9, to tidal influenced FA6, to again mangrove FA9, the sea level moved and setting become more towards upper shoreface FA3. Tidal flat to tidal bar become dominate in the area, with mangrove to tidal bar until termination of sediments in the area. The rise and fall in sea level could be linked to facies association governed by tectonic activities in the Sarawak basin. © 2019, Slovnaft VURUP a.s.