Coal Quality Distribution Analysis Based on Gamma Ray Log and Gamma-Gamma Ray Log in Area X, East Kalimantan

coal quality, proximate analysis, gamma ray and density log

Authors

  • Reva Putri Sevilla Geophysical Engineering, Universitas Pembangunan Nasional “Veteran” Yogyakarta, SWK No. 104 North Ring Road Street, Condongcatur, 55283
  • Y. Yatini Geophysical Engineering, Universitas Pembangunan Nasional “Veteran” Yogyakarta, SWK No. 104 North Ring Road Street, Condongcatur, 55283
  • Faid Muhlis PT. Bukit Baiduri Energi, Bukit Raya, Tenggarong Seberang, East Kalimantan, 75131
July 6, 2026
July 13, 2026

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This study was conducted in East Kalimantan with the objectives of identifying lithology from geophysical well-logging data, analysing the continuity of coal seams, analysing the distribution of coal quality based on proximate parameters, analysing the relationship between the most dominant proximate parameters and calorific value, and determining the rank of the coal. The data used included gamma-ray and density logs, lithological data from drilling, and proximate analysis data. Lithological interpretation was performed by integrating log responses with drilling data, while seam continuity was analyzed through borehole correlation. The results indicate that the study area consists of soil, silt, sand, mudstone, siltstone, coal, carbonaceous material, coaly shale, and sandstone. Correlation analysis identified six coal seams: S1, S2, S3, S4A, S4B, and S5. Coal quality analysis shows that Seam S4A has the highest Total Moisture (18.72%), Inherent Moisture (13.31%), and Fixed Carbon (41.40%). Seam S3 contains the highest Ash content (15.47%), Seam S2 has the highest Volatile Matter (42.55%), and Seam S5 records the highest Total Sulfur (3.55%) and Calorific Value (5887 kcal/kg adb). Correlation analysis reveals that ash content is the most influential proximate parameter affecting calorific value, showing a negative relationship: increasing ash content decreases calorific value. Based on ASTM D388 classification, seam S5 is classified as high-volatile C bituminous coal, whereas seams S1, S2, S3, S4A, and S4B are classified as subbituminous A coal.