Publications

The Gumai Formation stratigraphically occurs at the top of the Baturaja or Talang Akar Formation as a product of initial compression in Early Miocene. The continuation of a transgressive phase generated marine shale, siltstone and sandstone. The G4 Level, as part of the interested zone, is developed in almost all exploration wells in West Jambi II with good gas indications and has shaly (tight) sand characteristics. Rock physics cross plot analysis suggested that the reservoir has relatively the same AI characteristic with the shale or non reservoir above it, so it will need further methods to map the G4 reservoir potential distribution. Based on the condition mentioned above, to obtain a preliminary view of the potential reservoir distribution, that will become the model of the inversion later on, a spectral decomposition method is applied to the seismic data. We believe that even though the AI characters are relatively similar, the thickness difference of the reservoir could be extracted and tuned by some related sub band frequencies. A number of potential sub band frequencies were selected based on a 1D signal analysis (Complex CWT) where the results from sub-band frequencies analyzed by Spectral Decomposition are then selected and blended to describe this reservoir.