Identification of coal distribution based on drilling and geophysical logging: A case study from Samurangau, East Kalimantan

Coal is one of the major energy resources, and its utilization is strongly influenced by the quality and spatial distribution of subsurface reserves. This study aims to identify the position, thickness, and distribution pattern of coal seams in the Samurangau area, Biu, Muara Samu District, Paser Regency, East Kalimantan Province. The analysis was carried out using drilling and geophysical logging data, focusing on gamma ray and density log responses from several shallow boreholes. The results reveal 13 coal seams, sequentially named seams 15 to 3 from top to bottom, with thicknesses ranging from 0.40 to 18.10 m and occurring at depths of 1.50-233.10 m. Splitting was observed in seams 9, 8, 4, and 3, while some seams also exhibit thinning. Overall, the seams show a Northwest-Southeast distribution trend with a general dip toward the Southwest. These findings provide essential information to support further exploration, geological modeling, and mine planning in the study area.