Increasing the volume of hydrocarbons in place (HCIP) by identifying hydrocarbon prospect zones based on log and core data in the "RS" field limestone formation

Formation Evaluation not only plays an important role in oil and gas exploration but also in evaluating reservoirs. When the drilling operation has been completed, a decision is generally made between completing the well or plug and abandon the well. With the logging activity, then the decision can be taken considering the required data has been obtained from the log records. However, the determination of Water Saturation (Sw) cannot be obtained directly from log records, special methods are needed to find it according to the layer under study. In addition, the results of the log calculation will be used. The aim of this work is to obtain a hydrocarbon prospect layer (Net Pay), pore volume of hydrocarbons in the "S8" layer which can be used as a reference for further field development. Besides determining the appropriate method in calculating water saturation can be used as a reference in subsequent calculations in the "RS" field. Henceforth the parameters obtained are used to determine the Initial Oil Reserves using the Volumetric method. In research in Field R, there are 5 wells analyzed for the results of log records, namely Well RS-1, Well RS-5, Well RS-6, Well RS-2 and Well RS-7 the depth is 7098-7300 feet. The layer studied from the five wells has Limestone lithology and is a shally formation, because the shale content (Vshale) for these five wells is more than 10. Resistivity average around 4-12 Ωm. Therefore, the determination of Sw is carried out using the Indonesian Method. Based on the results of qualitative and quantitative validation, the Sw method chosen after being validated with core data, between Indonesia Formula and Simandoux, was chosen to be applied in the Field RS is Indonesia Formula. The net pay thickness of the five wells was obtained by cutting off Vshale, effective porosity, and Sw. In this paper, effective porosity, Vshale, and Sw cutoffs are used for 8, 45, and 70, respectively. Taking into account the net pay thickness of 56.5 feet, Area Area=8104.56 Acre, and N/G=56.5/302=0.183, the Hydrocarbon Pore Volume (HPV) can beobtained, namely HPV=14.83 MM Bbl.