Estimation of Reservoir Rock Porosity Using Multi- Attribute Analysis at ‘STA’ Field, North East Java Basin

Abstract

This study investigates the use of acoustic impedance inversion and seismic multi- attribute analysis to estimate porosity distribution and identify potential reservoir zones at STA Field, Northeast Java Basin. Accurate porosity estimation is essential for understanding reservoir quality and guiding field development decisions. The dataset includes 3D post-stack seismic data and well log data from three wells (STA1, STA2, and STA3). The methodology involves model-based inversion to generate acoustic impedance volumes. The crossplot of acoustic impedance and porosity log show moderate correlation in carbonate reservoir, therefore the total porosity volume is estimated along with other seismic attributes. The porosity values estimated by the multi-attribute analysis range between 0.27 and 0.39, with STA3 exhibiting the most consistent and thick high-porosity zone. The porosity map within the reservoir interval indicates that high-porosity zones (>0.33) are predominantly concentrated around STA3, following a southwest–northeast (SW– NE) trend. When overlaid with the time-structure map, the area surrounding STA3 located on a structural high (anticline) is identified as the most promising target for future well development. This study confirms that the integration of inversion and multi-attribute techniques enhances porosity estimation and supports more reliable reservoir characterization in geologically complex settings.