The Middle Miocene Balikpapan Formation is exposed in the Samarinda Anticlinorium, which forms part of the Lower Kutai Basin situated on East Kalimantan, Indonesia. The Balikpapan Formation is considered the main source rock for oil and gas fields in Lower Kutai Basin. This study integrates sedimentology, organic geochemistry, organic petrography and calcareous nannofossil analysis to characterize the depositional environment, to determine the source of the organic matter, and to assess the hydrocarbon potential of the Balikpapan Formation. The studied sections contain at one locality calcareous nannofossil assemblages with low diversity including , suggesting nannofossil zones NN4 – NN5 (upper Burdigalian - Langhian-lower Serravallian) are restricted to the Air Putih section in the northeastern part of the study area. Six facies associations were identified in the study area, comprising eleven lithofacies, interpreted as fluvial-deltaic to shallow marine in origin. The fine-grained lithofacies include shale, coaly shale and coal while the coarse-grained facies include sandstone and sandy conglomerates. The geochemical results (TOC) indicate that the analyzed samples have strongly varying total organic carbon (TOC) contents. The organic matter is composed of type III (gas-prone) and type II-III (mixed oil and gas prone) kerogen, with HI values ranging from 32 to 252 mg HC/g TOC. The Rock-Eval parameter T 409–441 °C and vitrinite reflectance values (0.40–0.67 %Rr) indicate that the sediments are immature to marginal mature. The rank of coal in the Balikpapan Formation ranges from the sub-bituminous to the high-volatile bituminous B stage.

中文翻译：

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印度尼西亚库泰盆地下游中中新统巴厘巴板组的油气潜力和沉积环境：沉积学、钙质超微化石、有机地球化学和有机岩相学综合方法


中新世巴厘巴板地层暴露在三马林达背斜层中，该地层是印度尼西亚东加里曼丹下库泰盆地的一部分。巴厘巴板组被认为是下库泰盆地油气田的主要烃源岩。这项研究综合了沉积学、有机地球化学、有机岩相学和钙质超微化石分析来表征沉积环境，确定有机质来源，并评估巴厘巴板组的碳氢化合物潜力。研究的剖面包含一处多样性较低的钙质超微化石组合，表明超微化石带 NN4 – NN5（上 Burdigalian - Langhian - 下 Serravallian）仅限于研究区东北部的 Air Putih 剖面。研究区发现了 6 个相组合，包括 11 个岩相，解释为河流三角洲到浅海相。细粒岩相包括页岩、煤质页岩和煤，粗粒岩相包括砂岩和砂砾岩。地球化学结果 (TOC) 表明分析样品的总有机碳 (TOC) 含量差异很大。有机质由 III 型（易产气）和 II-III 型（易产油气）干酪根组成，HI 值范围为 32 至 252 mg HC/g TOC。岩石评估参数 T 409–441 °C 和镜质体反射率值 (0.40–0.67 %Rr) 表明沉积物处于未成熟到边缘成熟状态。巴厘巴板组煤的品级范围从次烟煤到高挥发性烟煤 B 级。