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 Asset 2 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 liner perforated 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.