ROCK PHYSICS ANALYSIS ON SHALY SANDSTONES OF TABUL FORMATION TARAKAN BASIN FOR RESERVOIR QUALITY AND DEPOSITIONAL ENVIRONMENT DETERMINATION

• Main Author: Powericho Luo Daely, Gabriel
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/44011
• Institution: Institut Teknologi Bandung

Tarakan Basin is one of the potential hydrocarbon basins in North Kalimantan Province. Formations proven as oil and gas reservoirs in this basin are Meliat Formation, Tabul Formation, Santul Formation, and Tarakan Formation, which deposited in Miocene to Pliocene. This study aims to map the distribution of reservoir quality in reservoir zones of Tabul Formation in the Tarakan Basin. This formation was deposited in the Middle Miocene to Late Miocene with a delta depositional environment approved by shaly sandstones. The analysis used is the Thomas-Stieber model that models the porosity relationship with shale content on the siliciclastic rocks. In determining reservoir zones, the INPEFA method is used from gamma ray logs as a guide for selecting reservoir zones. With this analysis, it is expected to map the quality of reservoir porosity and the distribution of shale composition in each reservoir in the Tabul Formation. The data used in this study consisted of eight wells, scattered in the Tarakan Basin from two different fields. There are four reservoir zones, determined by using INPEFA trend that depositioned when the regression of sea level happened, so the lithology is dominated by shaly sandstones. Based on the analysis of the Thomas-Stieber diagram using the left foot, which is associated with shaly sandstones, there is a tendency for the reservoir quality to be relatively better from zone 1 to zone 4 which is shallower, and the reservoir quality at the Sembakung Field in all zones is poorer than that of Bangkudulis Fields. In the Thomas-Stieber diagram analysis using the right foot, which is associated with sandy shalestones, there is a tendency that the shale content in the Sembakung Field is relatively more than Bangkudulis Fields