STATIC RESERVOIR MODELING AND RESERVE ESTIMATION OF RESERVOIR A, B, AND C, GUMAI FORMATION, TRONA FIELD, SOUTH SUMATRA BASIN

• Main Author: Isfan Fajar, Muhammad
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/29275
• Institution: Institut Teknologi Bandung

The Trona Field is an oil field which is located in Jambi Sub-basin, South Sumatra Basin. At the beginning, the main target in this field was Air Benakat Formation. After further development, a thick sandstone interval that could act as a reservoir was found in Gumai Formation, which is down beneath the Air Benakat Formation. Detailed reservoir modeling is needed in order to evaluate the oil reserve and to have a better understanding on reservoir interval in the Upper Gumai Formation. The study started with analyzing the lithofacies and facies association from the available core description data. Then, the electrofacies analysis is done by matching the lithofacies and wire line log data, in order to know the vertical distribution of the facies. Petrophysical analysis is done to get the property value and the cut-off of volume of clay, effective porosity and water saturation, which is required for property modeling in the next step. Seismic data interpretation is also done in order to know the reservoir geometry and the geological structure in Trona Field. Then, stochastic method (using variogram) is used in order to distribute the facies and reservoir property. The generated static model is then used to estimate the hydrocarbon reserve in Trona Field. Based on facies analysis, the research interval consists of four lithofacies; Stw, Shl, Stmr, and Str.The research interval was deposited in tide-dominated estuary, and consists of tidal mudflat, estuarine channel, and intertidal sand bar facies association. The main geology structure of Trona Field is anticline with northwest-southeast orientation. The static reservoir model and hydrocarbon volumetric calculation conclude that there are 1158 MSTB of STOOIP in reservoir A, 4044 MSTB of STOOIP in reservoir B and 2838 MSTB of STOOIP in reservoir C, which makes a total of 8040 MSTB of STOOIP in the research interval.