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ABSTRAK Nadia Ayu Zahwani
PUBLIC Suharsiyah

Core data is crucial to the characterization of oil and gas reservoirs. Reservoir characterization enables a more accurate estimation of reservoir reserves and prediction of reservoir performance. In addition, core data can be used to ascertain the classification of rocks, also known as rock typing. The properties of the rocks that compose oil and gas reservoirs can be determined using rock typing. Also, it enables the identification of potential zones for hydrocarbon production, the comprehension of fluid flow behavior, and the planning of efficient production operations. For a more precise determination of carbonate rock types, integrating petrophysical data with available fluid, rock, and geological information is necessary. This research will focus on identifying and analyzing the rock type of Indonesia's carbonate reservoirs in four regions of Indonesia. Before conducting rock typing, statistical data analysis was conducted for each field's distribution of porosity and permeability data. Rock typing uses Hydraulic Flow Unit (HFU), Pore Geometry Structure (PGS), Global Hydraulic Elements (GHE), Lucia, and Winland R35 methods. The result of rock typing in the four regions is that the PGS method has higher permeability prediction accuracy than the HFU method. Region 1 (West Papua) has a range of DRT 3 - 17 (HFU Method), RT 4 – 16 (PGS Method), GHE 1 – 8 (GHE Method), dominated by rock fabric class 3, and Mesopore type of pore throat. Region 2 (East Java) has a range of DRT 3 – 28 (HFU Method), RT 3 – 18 (PGS Method), GHE 1 – 10 (GHE Method), dominated by rocks fabric class 3 and 4, Microporous and Mesoporous pore throat type. Region 3 (Central Kalimantan) has a range of DRT 10 – 21 (HFU Method), RT 6 – 17 (PGS Method), GHE 0, 4 – 10 (GHE Method), dominated by rock fabric class 4, and Macroporous pore throat type. Region 4 (Central Sulawesi) has a range of DRT 8 – 11 (HFU Method), RT 4 – 8 (PGS Method), GHE 3 – 6 (GHE Method), dominated by rock fabric class 3, and Mesoporous type of pore throat.