TRIGONOMETRIC APPROACH TO CURVED PSEUDO ELASTIC IMPEDANCE (CPEI) AND PSEUDO ELASTIC IMPEDANCE-LITHOLOGY (PEI-L) ATTRIBUTES FOR RESERVOIR CHARACTERIZATION OF “CNDY” FIELD, EAST NATUNA BASIN

• Main Author: Cindy Putri, Nadya
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86284
• Institution: Institut Teknologi Bandung

The East Natuna Basin has great potential for exploration of new oil and gas resources. This study focuses on the "CNDY" field located in the basin in the Lower Terumbu Formation and the Gabus Formation. The main reservoirs in this study are shaly sandstone in the Lower Terumbu Formation and sandstone in the Gabus Formation. To separate lithology and fluid well, sensitive elastic parameters are required. Based on crossplot analysis of well log data, the sensitive elastic parameters for this study are Acoustic Impedance (AI) and Vp/Vs ratio, which are effective in distinguishing lithology and fluid. The AI volume analysis uses the Linear Programming Sparse Spike (LPSS) seismic inversion method because it obtains high-resolution impedance from low-resolution seismic data, making it more sensitive to thin layers. The Vp/Vs ratio analysis uses the AI/SI volume and Extended Elastic Impedance (EEI) methods. The results of the volume Vp/Vs ratio using the EEI method are more sensitive to identify hydrocarbons in thin layers compared to using the AI/SI method which is less sensitive to thin layers. The angle variation results in the EEI method show a linear trend, while the Rock Physics Template (RPT) wet sandstone shows a nonlinear trend. Therefore, reservoir characterization using Curved Pseudo Elastic Impedance (CPEI) and Pseudo Elastic Impedance-Lithology (PEI-L) attributes is required. The characterization approach is carried out on the RPT parameters to be analyzed, namely water saturation to observe fluid trends in the reservoir and porosity through the PEI-L attribute to observe lithological trends in the reservoir. The use of CPEI and PEIL attributes requires an RPT model approach using a trigonometric function approach to be applied to the relevant research area, and can be applied in various subsurface geological conditions.