Application of seismic attributes and post stack inversion to study different sand reservoir distribution, offshore Vietnam

Abstract

Nam Con Son Basin is one of the major hydrocarbon producing fields in offshore Vietnam. This field is characterized by complex tectonic settings with extensional activities and uplift events. The interest interval of the study area is the Post rift stage in Upper Miocene of Nam Con Son Basin which developed in a deep marine environment. Thus, the main sand reservoirs are recognized as turbidites with complex geometries which is challenging in understanding the reservoir properties based on conventional full stack seismic data. Goal of the study was to identify and predict the distribution of different sand reservoirs in Upper Miocene, using rock physics analysis and post stack inversion, in combination with seismic attribute analyses. Rock physics analysis greatly assists in the interpreted Post stack inversion by discriminating rock properties of different lithologies and fluids. RMS highlights amplitude anomalies correlated to coarser-grained sediments. Whereas, gas sand or stratigraphic features can be observed from high amplitude in low frequency using the attribute Spectral Decomposition. The gas bearing sand is low P-impedance while wet sand and shale show the higher P-impedance. As the results gained from these analyses, the distribution of different sand reservoirs were predicted based on the combination of Post Stack inversion and amplitude attributes. Furthermore, the special fluid (gas) bearing sand can be imaged by Spectral Decomposition and Post Stack inversion.