Implementation of Deterministic and Multimineral Method in Petrophysical Analysis for Identifying Low Resistivity Reservoir in Tesla Field, Air Benakat Formation, South Sumatera Basin

Abstract

The Tesla field is located in the South Sumatra Basin, where there is the Air Benakat Formation, with the constituent rocks being dominated by alternating sandstone and claystone so that it is a shaly sand environment with the potential to become a low-resistivity hydrocarbon reservoir. Hydrocarbon reservoirs generally have a resistivity log value of more than 10 Ωm; when a hydrocarbon reservoir has a low-resistivity value between 0.5 - 5 Ωm, it is referred to as a low-resistivity hydrocarbon reservoir. Initially, deterministic analysis was carried out to calculate the petrophysical parameters of the potentially become low-resistivity reservoirs. However, the results show a low validation value compared to the DST data, so an multimineral analysis is carried out which is expected to increase the validation value of the petrophysical parameters. The research began by analyzing well-logs data and mud-logs are used in the calculation of rock physical properties such as VCL, PHIE, SW, and Permeability, as well as in the analysis of the causes of low-resistivity hydrocarbon reservoirs. Based on the analysis, it can be concluded that after validating the DST data, the multimineral method has a higher validation value than the deterministic method and the low-resistivity reservoir in the Tesla Field is caused by the very fine grain size of the sandstone so that it can bind water significantly, the abundant shale content with the distribution of laminated, dispersed, and structural and the presence of the conductive mineral glauconite.