FREQUENCY GRADIENT OF SPECTRAL DECOMPOSITION FOR IDENTIFYING HYDROCARBON RESERVOIR - EXAMPLE FROM INDONESIAN FIELD

摘要

The application of frequency analysis, which is well known as spectral decomposition attributes, is believed to be effective tool to differentiate both lateral and vertical lithologic and pore-fluid changes. The application of frequency analysis has proven a success in gas sand reservoir. The spectral decomposition application is also showing the hydrocarbon anomaly in carbonate for several high resolution hazard survey data. In some cases, the frequency anomaly is normally consistent with AVO anomaly for gas sand reservoir. However, this consistency does not work for carbonate reservoir and more complex structure, since the anomaly is not appearing in the AVO analysis. In this paper, we present the advantage of spectral decomposition attributes, which is based on Continuous Wavelet Transform (CWT) algorithm, in identifying the hydrocarbon reservoir in sand, carbonate and complex structure reservoir. Knowing the difficulties and deviating result of spectral decomposition analysis in term of conventional low and high frequency analysis, we propose the frequency gradient instead of conventional spectral decomposition presentation. This technique provides more helpful tool in delineating hydrocarbon reservoir from the seismic data. Our example on seismic data from Indonesian field show good delineation of hydrocarbon reservoir particularly in carbonate reservoir.