S Sakti field situated 60 km to the west Prabumulih, South Sumatra. And this is part of the Golf Course area of oil and gas development are managed Asset2 PT. Pertamina EP Field Size is + 20 km2 trending North West - South East with major hydrocarbon production is oil from the Talang Akar Formation. Sakti Fields was discovered in 1930 by NKPM with initial production from wells S - 02 of 700 BOPD with a water cut (WC) 0 % Natural flow is commingle with linerperforated layer of A and B at DF depth (759-809) ft. The problems that always arise in the analysis of this is that we want to know how big the petrophysical parameters such as the volume of shale (Vshale) , effective porosity rocks (Øeff), and water saturation (Sw) in the interval zones porous both before and after the cut-off in its current condition. In addition, we want to know in depth how the area is porous and permeable in a layer that is being observed by Interactive Petrophysics software v 3.5 or we can call IP 3.5. Purpose of this study was to analyze the assessment data that is logging the well formation S-242, S-241, S-240, S-238, S-237, and S-233 on C Layer in S Fields with quantitative analysis. The goal is to determine the initial oil reserves (OOIP, stb) of the layer C in Sakti Fields and obtain the latest OOIP price . In addition, we can determine the amount of water saturation, effective porosity, and the magnitude Vshale.