STOCHASTIC INVERSION AND ROCK PHYSICS-BASED SEISMIC ATTRIBUTES FOR SHALY-SAND RESERVOIR CHARACTERIZATION, CASE STUDY: TAWUN FORMATION, NORTH EAST JAVA BASIN

• Main Author: Senoaji, Ferry
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70857
• Institution: Institut Teknologi Bandung

Reservoir characterization using seismic data (inversion and attributes) is an analysis to determine the lateral distribution of reservoir properties, unfortunately this analysis is limited by something called the rock physics bottleneck. Therefore, the authors want to apply a relatively new method, it is a rock-physics-based seismic attributes. The attribute is called PEIL/CPEI, this attribute was introduced by Avseth et al. in 2014 and has been tried for gas-filled sandstone reservoirs (Riyadi et al., 2020), and gas-filled carbonate reservoirs (Kumalasari and Winardhi, 2021). The author will try to apply this method to gas-filled shaly-sand reservoirs in the Tawun Formation. Considering that the object of this study is a shaly-sand reservoir which generally has a thin and layered thickness, the authors will use the stochastic inversion developed by Escobar et al. in 2006. Preliminary analysis shows that there are two reservoirs in the target formation, LTA-1A and LTA-2A reservoirs. The LTA-2A is a high Vsh reservoir with a thin thickness. The RPT model shows if the target interval is unconsolidated lithology. Stochastic inversion can produce good AI cubes, but Vp/Vs cubes at LTA-2A intervals are still not optimal. CPEI attributes can show fluid anomalies for shalysand reservoirs. As for the PEIL attribute, it still needs to be corrected, because the PEIL value is also correlated with shale volume (same as porosity). Lithology and fluid interpretation is carried out in the 17th realization. In the LTA-1A interval, high prospect zones are in the central and southwest areas, and medium prospect zones are in the north and east areas. Then for the LTA-2A interval, the zone with high prospects is right at the C-FS well, and even then it's not too wide.