Reservoir Distribution Analysis with Seismic Colored Inversion in Fluvial Deposition Environment West Natuna Basin

Abstract

West Natuna Basin is a fluvial deposition environment with thin-bed sand reservoir overlapping with shale and shaly sand. Inversion is applied using Seismic Colored Inversion which considered to provide with robust result to identify geological features such as sand channels’ continuity with low-acoustic impedance value alongside zone of interest. Seismic Colored Inversion can be made by inverting seismic data into Acoustic Impedance value which can be obtained by deriving data from well, as control, then utilized it to change the seismic data volume to Acoustic Impedance volume. By performing a lateral slicing along the target horizons, the distribution of sand channels can be identified. Therefore, the promising reservoir zone with low Acoustic Impedance value and the non-reservoir zone can be clearly distinguished. Slicing was performed in A1 horizon, showing low AI sand channels ranging from 12.000 up to 15.500 ((ft/s)*(g/cc)) spreading at the center of the map through the East. Slicing in B2 horizon, showing what appears to be sand channels with low AI value ranging from 16.000 up to 17.800 ((ft/s)*(g/cc)) spreading at the center of the map between the U1 and U3 well, and appears at the Northeast of the map.