Integrated Analysis of RGB-Blended Spectral Decomposition and Amplitude Variation with Frequency (AVF) in Carbonate Reservoir, Northeast Java Basin, Indonesia

Abstract

The Kujung Formation in the Northeast Java Basin is a major carbonate reservoir formed in an open marine to upper bathyal environment, characterized by high porosity due to dissolution and dolomitization. This study aims to identify new hydrocarbon prospect zones by integrating Spectral Decomposition and Amplitude Variation with Frequency (AVF) methods, using 3D Pre-Stack Time Migration (PSTM) seismic and well log data. Log sensitivity analysis was performed to assess the distribution of carbonate reservoirs, while seismic signals were decomposed into low, medium, and high-frequency components using Continuous Wavelet Transform (CWT). These frequency components were visualized as single-frequency attributes and combined using RGB blending to highlight shelf-edge carbonate features. The AVF method was applied to analyze amplitude attenuation across frequencies and extract intercept and gradient attributes, where zones with high intercepts and sharp negative gradients were interpreted as hydrocarbon indicators. The integrated approach identified six new zones of interest, marked by high-intensity anomalies in RGB-blended volumes and distinctive AVF signatures. This study demonstrates that combining spectral decomposition and AVF is effective for mapping carbonate reservoir heterogeneity and delineating hydrocarbon prospect zones in the Northeast Java Basin.