RESERVOIR CHARACTERIZATION USING MODEL- BASED SEISMIC INVERSION AND MULTI ATTRIBUTE SEISMIC AT NORTH SUMATRA BASIN

Abstract

The Model-Based acoustic impedance inversion approach and Multi-Attribute analysis were used to predict porosity distribution in the North Sumatra Basin. Accurate porosity estimation is essential for understanding reservoir quality. The objective of this study is to map the porosity distribution within the study area of the North Sumatra Basin. The data used in this study consist of well data from Wells A, B, and C, as well as post-stack 3D seismic data. The methodology applied involves model-based P-impedance inversion and Multi-Attribute analysis. The inversion results were used as one of the input attributes in the Multi-Attribute analysis for porosity prediction. The initial correlation between porosity and impedance was only 0.65, which was considered insufficient for reliable porosity estimation. Therefore, Multi-Attribute analysis was applied to improve prediction accuracy by combining several relevant seismic attributes. The correlation between the inverted P-impedance log and the original log was high, at 0.96, indicating that the inversion results are highly representative. From the training and validation process using the three best attributes, a training correlation of 0.70 and a validation correlation of 0.88 were obtained. The porosity distribution shows high values (0.17–0.20 v/v) around Well B. Another high-porosity zone was also identified in the eastern part of the survey area, with porosity values ranging from approximately 0.17 to 0.20 (v/v).